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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2015	Mar. 01, 2016	Jun. 30, 2015
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Trading Symbol	CBIO
Entity Registrant Name	CATALYST BIOSCIENCES, INC.
Entity Central Index Key	0001124105
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		11,430,104
Entity Public Float			$ 63,198,734

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 29,096	$ 1,544
Short-term investments	3,402
Restricted cash	33,794	50
Deposits	133	278
Accounts receivable	492	95
Prepaid and other current assets	1,781	103
Total current assets	68,698	2,070
Restricted cash, noncurrent	125
Property and equipment, net	698	911
Total assets	69,521	2,981
Current liabilities:
Accounts payable	939	249
Accrued compensation	926	281
Other accrued liabilities	535	30
Deferred revenue, current portion	438	1,750
Deferred rent, current portion	19	26
Redeemable convertible notes	33,743
Derivative liability	1,156
Total current liabilities	37,756	2,336
Deferred revenue, noncurrent portion	292	729
Deferred rent, noncurrent portion	48
Warrant liability		391
Total liabilities	38,096	3,456
Commitments and contingencies
Convertible preferred stock:
Convertible preferred stock		108,877
Stockholders' equity (deficit):
Preferred stock
Common stock, $0.001 par value, 105,000,000 shares and 110,000,000 shares authorized as of December 31, 2015 and 2014, respectively; 11,430,085 and 370,944 shares issued and outstanding as of December 31, 2015 and 2014, respectively.	11
Additional paid-in capital	162,450	6,923
Accumulated other comprehensive income	1
Accumulated deficit	(131,037)	(116,275)
Total stockholders' equity (deficit)	31,425	(109,352)
Total liabilities, convertible preferred stock and stockholders' equity (deficit)	$ 69,521	$ 2,981

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Convertible preferred stock, par value	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0	88,469,871
Convertible preferred stock, shares issued	0	87,405,011
Convertible preferred stock, shares outstanding	0	87,405,011
Convertible preferred stock, aggregate liquidation preference	$ 0	$ 118,678
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	105,000,000	110,000,000
Common stock, shares issued	11,430,085	370,944
Common stock, shares outstanding	11,430,085	370,944

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Contract revenue	$ 1,750	$ 1,813	$ 523
Operating expenses:
Research and development	5,958	5,267	6,557
General and administrative	9,594	4,055	4,086
Total operating expenses	15,552	9,322	10,643
Loss from operations	(13,802)	(7,509)	(10,120)
Interest and other income	518	896	154
Interest expense	(1,478)
Net loss	$ (14,762)	$ (6,613)	$ (9,966)
Net loss per common share, basic and diluted	$ (3.33)	$ (17.99)	$ (27.29)
Shares used to compute net loss per common share, basic and diluted	4,429,093	367,586	365,214

Consolidated Statement of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net loss	$ (14,762)	$ (6,613)	$ (9,966)
Other comprehensive income (loss):
Unrealized gain on available-for-sale securities, net of tax	1
Total comprehensive loss	$ (14,761)	$ (6,613)	$ (9,966)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Consolidated Statements of Convertible Preferred Stock and Stockholders Equity (Deficit) - USD ($) $ in Thousands	Total	Series CC Convertible Preferred Stock	Series D Convertible Preferred Stock	Series E Convertible Preferred Stock	Redeemable Convertible Preferred Stock	Convertible Preferred Stock Amount	Convertible Preferred Stock Amount Series CC Convertible Preferred Stock	Convertible Preferred Stock Amount Series D Convertible Preferred Stock	Convertible Preferred Stock Amount Series E Convertible Preferred Stock	Convertible Preferred Stock Amount Series F Convertible Preferred Stock	Common Stock Amount	Common Stock Amount Redeemable Convertible Preferred Stock	Additional Paid-In Capital	Additional Paid-In Capital Redeemable Convertible Preferred Stock	Accumulated Other Comprehensive Income	Accumulated Deficit
Balance (in shares) at Dec. 31, 2012											365,214
Balance at Dec. 31, 2012	$ (93,340)												$ 6,356			$ (99,696)
Balance at Dec. 31, 2012						$ 98,899
Balance (in shares) at Dec. 31, 2012						78,932,729
Stock based compensation expense associated with vesting of stock awards	298												298
Issuance of stock, value							$ 4,961	$ 781
Issuance of stock, shares							3,907,512	629,630
Net loss	(9,966)															(9,966)
Balance (in shares) at Dec. 31, 2013											365,214
Balance at Dec. 31, 2013	(103,008)												6,654			(109,662)
Balance at Dec. 31, 2013						$ 104,641
Balance (in shares) at Dec. 31, 2013						83,469,871
Stock based compensation expense associated with vesting of stock awards	244												244
Stock options exercised for cash, value	$ 25												25
Stock options exercised for cash, shares	5,730										5,730
Issuance of stock, value						$ 4,236
Issuance of stock, shares									3,935,140
Net loss	$ (6,613)															(6,613)
Balance (in shares) at Dec. 31, 2014											370,944
Balance at Dec. 31, 2014	(109,352)												6,923			(116,275)
Balance at Dec. 31, 2014	$ 108,877					$ 108,877
Balance (in shares) at Dec. 31, 2014	87,405,011	46,429,980	629,630	3,935,140		87,405,011
Stock based compensation expense associated with vesting of stock awards	$ 326												326
Stock options exercised for cash, value	$ 13												13
Stock options exercised for cash, shares	3,820										3,820
Issuance of stock, value						$ 7,259
Issuance of stock, shares						5,788,522
Conversion of convertible securities, value	$ 117,647				$ 241	$ (117,647)				$ 1,511	$ 6		117,641	$ 241
Conversion of convertible securities, shares						(94,705,256)				1,511,723	6,148,161	25,787
Conversion of convertible securities, shares						(94,705,256)				1,511,723	6,148,161	25,787
Conversion of preferred stock warrants to common stock warrants in connection with merger	774												774
Issuance of common stock in connection with reverse merger, value	36,537										$ 5		36,532
Issuance of common stock in connection with reverse merger, shares											4,881,373
Unrealized gain on available-for-sale securities, net of tax	1														$ 1
Net loss	(14,762)															(14,762)
Balance (in shares) at Dec. 31, 2015											11,430,085
Balance at Dec. 31, 2015	$ 31,425										$ 11		$ 162,450		$ 1	$ (131,037)
Balance (in shares) at Dec. 31, 2015	0

Consolidated Statements of Convertible Preferred Stock and Stockholders Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net of issuance costs	$ 96	$ 28
Series CC Convertible Preferred Stock
Net of issuance costs			$ 4
Series D Convertible Preferred Stock
Net of issuance costs			$ 19

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Activities
Net loss	$ (14,762)	$ (6,613)	$ (9,966)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	326	244	298
Depreciation and amortization	470	680	974
Non-cash interest expense on convertible notes	1,478
Loss on disposal of fixed assets	15	78
Impairment of patent assets		53
Gain on extinguishment of redeemable convertible notes	(52)
Change in fair value of warrant liability	(91)	(354)
Change in fair value of derivative liability	(242)
Changes in operating assets and liabilities:
Accounts receivable	(79)	1	(52)
Prepaid and other current assets	(1,350)	99	54
Accounts payable	(4,273)	(106)	11
Accrued compensation and other accrued liabilities	1,150	(2)	(247)
Deferred rent	41	(156)	(138)
Deferred revenue	(1,749)	(313)	2,792
Net cash flows used in operating activities	(19,118)	(6,389)	(6,274)
Investing Activities
Proceeds from the reverse merger	23,931
Proceeds from maturities of investments	13,823
Purchases of property and equipment	(272)		(41)
Change in restricted cash	(125)
Proceeds from sale of property and equipment		98
Net cash flows provided by (used in) investing activities	37,357	98	(41)
Financing Activities
Release of restricted cash due to conversion and redemption of redeemable convertible notes	3,255
Payments for the redemption of redeemable convertible notes	(3,020)
Proceeds from issuance of convertible preferred stock, net of issuance costs	7,259	4,982	5,742
Proceeds from issuance of convertible notes and warrants to related parties	1,888
Repurchase of common stock in connection with equity award assumed	(82)
Proceeds from the exercise of common stock options	13	25
Net cash flows provided by financing activities	9,313	5,007	5,742
Net increase (decrease) in cash and cash equivalents	27,552	(1,284)	(573)
Cash and cash equivalents at beginning of year	1,544	2,828	3,401
Cash and equivalents at end of year	29,096	$ 1,544	$ 2,828
Supplemental Disclosure of Non-Cash Investing and Financing Information:
Conversion of convertible notes to Series F convertible preferred stock	1,511
Investment securities received from the reverse merger	17,223
Redeemable convertible notes assumed upon reverse merger	37,073
Issuance of common stock in connection with conversion of convertible notes	241
Derivative liability related to redeemable convertible notes	1,455
Conversion of preferred stock warrant liabilities to equity upon reverse merger
Supplemental Disclosure of Non-Cash Investing and Financing Information:
Conversion of stock	774
Conversion of preferred stock to equity upon reverse merger
Supplemental Disclosure of Non-Cash Investing and Financing Information:
Conversion of stock	$ 117,647

Nature of Operations

12 Months Ended

Dec. 31, 2015

Nature of Operations

1.	Nature of Operations

Catalyst Biosciences, Inc. (the “Company” or “Catalyst”), is a clinical-stage biotechnology company focused on engineering proteases as therapeutics for hemophilia, hemeostasis, complement-mediated diseases, and other unmet medical needs. Its facilities are located in South San Francisco, California and it operates in one segment. The Company’s current customers, engaged principally through collaborations are other pharmaceutical and biotechnology companies, who are also engaged in developing and commercializing therapies for patients in the areas of hemophilia and complement-mediated diseases.

Reverse Merger

Prior to August 20, 2015, the name of the Company was Targacept. On August 20, 2015, Targacept completed its business combination with Old Catalyst” in accordance with the terms of an Agreement and Plan of Merger, dated as of March 5, 2015, as amended on May 6 and May 13, 2015 (the “Merger Agreement”), by and among Targacept, Talos Merger Sub, Inc. (“Merger Sub”) and Old Catalyst, pursuant to which Merger Sub merged with and into Old Catalyst, with Old Catalyst surviving as a wholly-owned subsidiary of Targacept (the “Merger”). Also on August 20, 2015, in connection with, and prior to the completion of, the Merger, Targacept effected a 7-for-1 reverse stock split of its common stock (the “Reverse Stock Split”) and changed its name from Targacept, Inc. to Catalyst Biosciences, Inc. Following the completion of the merger, the business conducted by the Company became primarily the business conducted by Old Catalyst described in the paragraph above.

These consolidated financial statements reflect the historical results of Old Catalyst prior to the completion of the merger, and do not include the historical results of Targacept prior to the completion of the merger. All 2015, 2014 and 2013 share and per share disclosures have been adjusted to reflect the exchange of shares in the merger, and the 7-for-1 reverse stock split of the common stock on August 20, 2015. Under U.S. generally accepted accounting principles (“GAAP”), the merger is treated as a “reverse merger” under the purchase method of accounting. For accounting purposes, Old Catalyst is considered to have acquired Targacept. See Note 7 - Reverse Merger for further details on GAAP accounting treatment.

Liquidity

We had an accumulated deficit of $131.0 million as of December 31, 2015 and expect to continue to incur losses for the next several years. As of December 31, 2015, we had $32.5 million in cash, cash equivalents and short-term investments. Management believes that the currently available resources will provide sufficient funds to enable us to meet its operating plan for at least the next fifteen months. However, if we anticipated operating results are not achieved in future periods, management believes that planned expenditures may need to be reduced in order to extend the time period over which the then-available resources would be able to fund our operations.

On November 30, 2015, we entered into a Letter of Agreement (LoA) with a third-party manufacturer concerning the development and manufacturing of our human Factor VIIa. The LoA has a scope of work associated with initial key activities of the overall project and commits us to $1.5 million in payments, including prepayment of $1.1 million. For the year ended December 31, 2015, we recognized $0.1 million of the $1.1 million prepaid amount related to the Letter of Agreement in research and development expense.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2015

Summary of Significant Accounting Policies

2.	Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements include the accounts of the Company and its subsidiaries. Intercompany accounts and transactions have been eliminated in consolidation. The Company’s consolidated financial statements have been prepared in accordance with GAAP.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, convertible notes and related warrants up to the date of conversion, common stock and stock-based compensation. The Company bases its estimates on various assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ from those estimates.

Cash and Cash Equivalents

The Company invests its excess cash in bank deposits, consisting primarily of money market mutual funds. The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents.

Restricted Cash

Restricted cash consists primarily of certain checking, money market and certificate of deposit accounts that are: (i) pledged to or held in a segregated escrow account by the Company’s correspondent banks for the benefit of the holders of the redeemable convertible notes in order to facilitate the payment of the redeemable convertible notes upon redemption or at maturity as discussed in Note 3 - Fair Value Measurements or (ii) pledged as collateral for the Company’s corporate credit card and deposit for its facility lease.

Fair Value of Financial Instruments

The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date.

The fair value hierarchy requires that an entity maximize the use of observable inputs when estimating fair value. The fair value hierarchy includes the following three-level classification which is based on the market observability of the inputs used for estimating the fair value of the assets or liabilities being measured:

Level 1 – Quoted prices in active markets for identical assets or liabilities.

Level 2 – Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3 – Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability.

Fair value accounting is applied for all financial assets and liabilities and non-financial assets and liabilities that are recognized at fair value in the financial statements on a recurring basis (at least annually).

Property and Equipment

Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets, which are three years for computer equipment and software, and three to seven years for laboratory and office equipment, furniture and leasehold improvements.

Intangible Assets

Intangible assets are amortized over their useful lives in a manner that best reflects their economic benefit. Intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. We do not have any indefinite-lived intangible assets.

Intangible assets represent patent rights purchased in 2009 in the amount of $0.1 million that were being amortized over their estimated useful life of 20 years, or life of the patent whichever is shorter, using the straight-line method. Annual amortization was $0 and $883 for 2015 and 2014, respectively. The Company abandoned this patent in 2014. No further amortization is necessary. The total amount amortized through 2014 was $0.02 million and the remaining $0.05 million was written off to amortization expense during 2014 in the accompanying statements of operations.

Investments

All investments have been classified as “available-for-sale” and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments at the time of purchase and reevaluates such designation as of each balance sheet date. Unrealized gains and losses are excluded from earnings and are reported as a component of comprehensive loss. Realized gains and losses and declines in fair value determined to be other-than-temporary, if any, on available-for-sale securities are included in interest and other income. The cost of securities sold is based on the specific-identification method. Interest on short-term investments is included in interest and other income.

Fair Value of Financial Instruments

Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and accounts receivable. The Company’s investment policy restricts cash investments to high credit quality, investment grade investments. The Company believes that it has established guidelines for investment of its excess cash that maintain safety and liquidity through its policies on diversification and investment maturity. The Company is exposed to credit risk in the event of default by the institutions holding the cash and cash equivalents to the extent of the amounts recorded on the balance sheets.

Derivative Liability

The embedded redemption feature in the redeemable convertible notes, which are convertible into shares of the Company’s common stock, is accounted for as a derivative liability at its estimated fair value. The derivative is subject to remeasurement at the end of each reporting period, with changes in fair value recognized as a component of interest and other income, in the consolidated statements of operations. The Company will continue to adjust the liability for changes in fair value until the earlier of the conversion, redemption or maturity of the redeemable convertible notes.

Revenue Recognition

The Company enters into collaboration arrangements that may include the receipt of payments for up-front license fees, success-based milestone payments, full time equivalent based payments for research services, and royalties on any future sales of commercialized products that result from the collaborations.

Revenue is recognized when the four basic criteria for revenue recognition are met: (1) persuasive evidence of an arrangement exists; (2) transfer of technology has been completed or services have been rendered; (3) the fee is fixed or determinable; and (4) collectability is reasonably assured.

Revenue recognition for multiple element revenue arrangements will have deliverables associated with the arrangement divided into separate units of accounting provided that (i) a delivered item has value to the customer on a standalone basis and (ii) if the arrangement includes a general right of return relative to the delivered item, delivery or performance of the undelivered item is considered probable and substantially in the control of the vendor. As a biotechnology company with unique and specialized technological undelivered performance obligations associated with its collaborations, the Company’s multiple element arrangements most often involve deliverables and consideration that do not meet the criteria for having stand-alone value.

Deliverables and performance obligations are accounted for under a single unit of accounting when they do not have stand-alone value and the related consideration is recognized as revenue over the estimated period of when the performance obligations are to be performed. The revenue is recognized on a proportional performance basis when the levels of the performance obligations under an arrangement can be reasonably estimated and on a straight-line basis when they cannot.

The Company’s collaboration agreements entitle it to additional payments upon the achievement of performance-based milestones related to product development, regulatory actions and commercial events in certain geographic areas. Milestones that are not deemed probable or that are tied to counter-party performance are not included in the Company’s revenue until the performance conditions are met. If a collaborative agreement milestone is deemed to be substantive, as defined in the accounting rules, the Company is permitted to recognize revenue related to the milestone payment in its entirety.

In the event milestones are deemed non-substantive, the Company recognizes, and defers if applicable, payments for the achievement of such non-substantive milestones over the estimated period of performance applicable to each collaborative agreement using the proportional performance method or on a straight-line basis, as appropriate.

Amounts received under a collaborative agreement prior to satisfying revenue recognition criteria are recorded as deferred revenue in the accompanying consolidated balance sheets. Deferred revenue is recorded on the Company’s consolidated balance sheet as short-term or long-term based on its best estimate as to when such revenue will be recognized. Short-term deferred revenue consists of amounts that the Company expects to recognize as revenue in the next 12 months. Amounts that the Company expects will not be recognized prior to the next 12 months are classified as long-term deferred revenue.

The Company’s performance obligations under its collaboration arrangements also consist of participation on steering committees and the performance of other research and development and business development services. The timing for satisfying these performance obligations can be difficult to estimate and can be subject to change over the course of these agreements. A change in the estimated timing for satisfying the Company’s performance obligations could change the timing and amount of revenue that the Company recognizes and records in future periods.

Research and Development Expenses

Research and development costs are expensed as incurred. Research and development costs consist of payroll and other personnel-related expenses, laboratory supplies and reagents, contract research and development services, and consulting costs, as well as allocations of facilities and other overhead costs. Under the Company’s collaboration agreements, certain specific expenditures are reimbursed by third parties. During the years ended December 31, 2015, 2014 and 2013, the Company recorded a reduction to research and development expenses of $0.9 million, $0.4 million, and $0.4 million, respectively related to these reimbursements.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and accounts receivable, resulting from research and development pass through expense reimbursement. The Company’s accounts receivable at December 31, 2015 was $0.5 million, of which $0.4 million was due from Pfizer Inc. (“Pfizer”), and $0.1 million was due was due from our landlord CBRE for tenant improvements reimbursement. The Company has incurred no credit losses to date. The Company does not require collateral from its collaboration partners.

Income Taxes

Income taxes are computed using the liability method. Deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse.

The Company follows the authoritative guidance on accounting for uncertainty in income taxes. This guidance prescribes a more-likely-than-not threshold for financial statement recognition and measurement of a tax position taken in the Company’s income tax returns. This interpretation also provides guidance on accounting for interest and penalties and associated with tax positions, accounting for income taxes in interim periods and income tax disclosures.

The Company’s policy is to include penalties and interest expense related to income taxes as a component of other expense and interest expense, respectively, as necessary.

Stock-Based Compensation

The Company measures the cost of employee and director services received in exchange for an award of equity instruments based on the fair value of the award on the date of grant and recognizes the related expense over the period during which the employee or director is required to provide service in exchange for the award on a straight-line basis.

The Company uses the Black-Scholes option-pricing valuation model to estimate the grant-date fair value of stock-based awards. The determination of fair value for stock-based awards on the date of grant using an option-pricing model requires management to make certain assumptions regarding a number of variables. The Company records stock-based compensation as compensation expense, net of the estimated impact of forfeited awards. The Company applies a forfeiture rate to stock-based compensation expense using historical data to estimate pre-vesting option forfeitures. The Company estimates forfeitures at the time of grant, and revises those estimates in subsequent periods if actual forfeitures differ materially from those original estimates. As such, the Company recognizes stock-based compensation expense only for those stock-based awards that are expected to vest, over their requisite service period, based on the vesting provisions of the individual grants.

For nonemployee stock-based awards, the measurement date on which the fair value of the stock-based award is calculated is equal to the earlier of (i) the date at which a commitment for performance by the counterparty to earn the equity instrument is reached or (ii) the date at which the counterparty’s performance is complete. The Company recognizes stock-based compensation expense for the fair value-based measurement of the nonemployee awards using the Black Scholes option-pricing valuation model and the awards are typically subject to periodic re-measurement over the period that services are rendered.

Deferred Rent

The Company’s facilities lease agreement provides for an escalation of rent payments each year. The Company records rent expense on a straight-line basis over the term of the lease. The difference between the amount of expense recognized and the amount of rent paid is recorded as deferred rent in the accompanying consolidated balance sheets.

Net Loss per Share

Basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss of the Company for all periods presented.

Fair Value Measurements

12 Months Ended

Dec. 31, 2015

Fair Value Measurements

3.	Fair Value Measurements

For a description of the fair value hierarchy and our fair value methodology, see “Note 2 – Summary of Significant Accounting Policies”. As of December 31, 2015 and 2014, the Company’s highly liquid money market funds included within cash equivalents and restricted cash including deposit in an escrow account are financial assets that are valued using Level 1 inputs. The Company classifies its municipal bonds and corporate notes as Level 2. Level 2 inputs for the valuations are limited to quoted prices for similar assets or liabilities in active markets and inputs other than quoted prices that are observable for the asset or liability. There were no transfers in or out of Level 1 and Level 2 during the periods presented.

Liabilities that are measured at fair value consist of the derivative liability and the warrant for convertible preferred stock that utilize Level 3 inputs. There were no transfers in or out of Level 3 during the periods presented.

The following tables present the fair value hierarchy for assets and liabilities measured at fair value on a recurring basis as of December 31, 2015 and 2014 (in thousands):


	December 31, 2015
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds	$	28,927	$	—	$	—	$	28,927
Restricted cash (money market funds)⁽¹⁾		33,919		—		—		33,919
Municipal bonds		—		296		—		296
Corporate notes		—		3,106		—		3,106

Total financial assets	$	62,846	$	3,402	$	—	$	66,248

Financial liabilities:
Derivative liability	$	—	$	—	$	1,156	$	1,156

Total financial liabilities	$	—	$	—	$	1,156	$	1,156

(1)	$125,000 of restricted cash serves as collateral for the Company’s corporate credit card and deposit for its facility lease.


	December 31, 2014
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds	$	1,496	$	—	$	—	$	1,496
Restricted cash (money market funds)⁽¹⁾		50		—		—		50

Total financial assets	$	1,546	$	—	$	—	$	1,546

Financial liabilities:
Warrant for convertible preferred stock liability	$	—	$	—	$	391	$	391

Total financial liabilities	$	—	$	—	$	391	$	391

(1)	$50,000 of restricted cash serves as collateral for the Company’s corporate credit card and deposit for its facility lease.

The fair value of the liability related to the warrant for convertible preferred stock was measured using the Black-Scholes option-pricing model. Inputs used to determine the estimated fair value of the warrant liability included the estimated fair value of the underlying convertible preferred stock at the valuation measurement date, the remaining contractual term of the warrant, risk-free interest rates, expected dividends and expected volatility of the price of the underlying preferred stock.

The following table presents the activity for the liability related to the warrant for convertible preferred stock for the year ended December 31, 2015 and 2014 (in thousands):


	Warrant Liability
Balance as of December 31, 2013	$	—
Issuance of preferred stock warrants		745
Change in fair value included in interest and other income		(354	)

Balance as of December 31, 2014	$	391
Issuance of preferred stock warrants		474
Change in fair value included in interest and other income		(91	)
Reclassification of warrant liability to equity upon conversion to common stock warrants		(774	)

Balance as of December 31, 2015	$	—

The fair value of the derivative liability is measured using the Black-Scholes option-pricing valuation model. Inputs used to determine the estimated fair value of the conversion option include the fair value of the underlying common stock at the valuation measurement date, the remaining contractual term of the conversion option, risk-free interest rates, expected dividends and expected volatility of the price of the underlying common stock. In addition, the Company estimated the convertible redeemable note exchange rate based on an analysis of its actual exchange of notes for cash redemption or exchange of notes for conversion to common stock. See Note 9 - Redeemable Convertible Notes for further detail.

The following table presents the activity for the derivative liability for the year ended December 31, 2015 (in thousands):


	Derivative Liability
Balance as of December 31, 2014	$	—
Issuance of derivative issued with the redeemable convertible notes		1,455
Change in fair value included in interest and other income		(242	)
Gain on extinguishment of redeemable convertible notes		(52	)
Conversion of convertible notes to common stock		(5	)

Balance as of December 31, 2015	$	1,156

The estimated reporting date fair value-based measurement of the derivative liability was calculated using the Black-Scholes valuation model, based on the following weighted-average assumptions for the year ended December 31, 2015:


	Year Ended December 31,
	2015
Expected term		2.00 years
Expected volatility		81.7	%
Risk-free interest rate		1.06	%
Expected dividend yield		0	%

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Financial Instruments

12 Months Ended

Dec. 31, 2015

Financial Instruments

4.	Financial Instruments

Cash equivalents, restricted cash and short-term and long-term investments, all of which are classified as available-for-sale securities, consisted of the following (in thousands):


December 31, 2015	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Money market funds	$	28,927	$	—	$	—		$	28,927
Restricted cash (money market funds)		33,919		—		—			33,919
Municipal bonds		295		1		—			296
Corporate notes		3,106		1		(1	)		3,106

Total financial assets	$	66,247	$	2	$	(1	)	$	66,248

Classified as:
Cash and cash equivalents								$	28,927
Restricted cash (money market funds)									33,919
Short-term investments									3,402

								$	66,248


December 31, 2014	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Money market funds	$	1,496	$	—	$	—		$	1,496
Restricted cash (money market funds)		50		—		—			50

Total financial assets	$	1,546	$	—	$	—		$	1,546

Classified as:
Cash and cash equivalents								$	1,496
Restricted cash (money market funds)									50

								$	1,546

As of December 31, 2015, the remaining contractual maturities of available-for-sale securities was less than one year. There have been no significant realized gains or losses on available-for-sale securities for the periods presented.

Property and Equipment

12 Months Ended

Dec. 31, 2015

Property and Equipment

5.	Property and Equipment

Property and equipment consisted of the following (in thousands):


	December 31,
	2015			2014
Laboratory and office equipment	$	4,458		$	5,027
Furniture		321			311
Leasehold improvements		1,591			1,515
Computer equipment		21			285
Software		8			422

		6,399			7,560
Less accumulated depreciation and amortization		(5,701	)		(6,649	)

Property and equipment, net	$	698		$	911

Property and equipment depreciation and amortization expense for the years ended December 31, 2015, 2014 and 2013 was $0.5 million, $0.7 million, and $1.0 million, respectively.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2015

Commitments and Contingencies

6.	Commitments and Contingencies

Operating Leases

On February 23, 2015, the Company entered into a new sub-lease, as sub-lessee, for the portion of the space it occupied in its headquarters building. The initial term of the sub-lease was set to expire on August 31, 2015. On June 8, 2015 the Company exercised its right to extend the sub-lease term through February 27, 2018. On March 1, 2015, the Company obtained a letter of credit in the amount of $0.05 million, fully secured by cash held in the Company’s bank account, to satisfy the amount of the security deposit. In September 2015, the Company increased a letter of credit to $0.13 million, fully secured by cash held in the Company’s bank account, to satisfy the amount of the security deposit.

The Company’s rental expense under its operating leases was $0.7 million, $1.0 million and $1.0 million for the years ended December 31, 2015, 2014 and 2013, respectively.

Future minimum lease payments under all non-cancelable operating leases at December 31, 2015, were as follows (in thousands):


Year ending December 31,
2016	$	723
2017		745
2018		125

Total future minimum lease payments	$	1,593

License Agreement Obligations

Under its technology license agreements to acquire certain technology rights, the Company has an obligation to pay minimum fees and then royalties based upon a percentage of any net sales of licensed products. License fees payable under the technology license agreements are $0.1 million in 2013 and each year thereafter until royalties commence. The technology license agreements also provide for future payments to be made by the Company upon the achievement of development milestones or cumulative sales milestones. Pursuant to the license and collaboration agreement with ISU Abxis (see Note 13 - Collaborations), the Company may be obligated to pay ISU Abxis up to $2.0 million in potential milestone payments. At December 31, 2015, no such milestones have been achieved. Under its agreement with Pfizer, which terminated as of June 2015, the Company may be obligated to make milestone and royalty payments to Pfizer. The final terms of this agreement have not been established.

Reverse Merger

12 Months Ended

Dec. 31, 2015

Reverse Merger

7.	Reverse Merger

Old Catalyst completed the Merger with Targacept as discussed in Note 1. Based on the terms of the Merger, Old Catalyst was deemed the acquiring company for accounting purposes, and the transaction has been accounted for as a reverse acquisition under the asset acquisition method of accounting in accordance with U.S. GAAP. Accordingly, the assets and liabilities of Targacept have been recorded as of the Merger closing date at estimated fair value.

Immediately prior to and in connection with the Merger, each share of Old Catalyst preferred stock outstanding was converted into shares of Old Catalyst common stock at ratios determined in accordance with the Old Catalyst certificate of incorporation then in effect. Under the terms of the Merger Agreement, at the effective time of the Merger, the Company issued shares of its common stock to Old Catalyst stockholders, at an exchange rate of 0.0382 shares of common stock, after taking into account the Reverse Stock Split, in exchange for each share of Old Catalyst common stock outstanding immediately prior to the Merger. The exchange rate was calculated by a formula that was determined through arms-length negotiations between Targacept and Old Catalyst. The Company assumed all of the outstanding options, whether or not vested, under the Catalyst 2004 Stock Plan, as amended (the “Catalyst Plan”), all of the standalone options of Old Catalyst that were not issued under the Catalyst Plan, and the warrants of Old Catalyst, whether or not vested, outstanding immediately prior to the Merger, with such options and warrants henceforth representing the right to purchase a number of shares of the Company’s common stock equal to 0.0382 multiplied by the number of shares of Old Catalyst common stock previously represented by such options and warrants. For accounting purposes, the Company is also deemed to have assumed the Targacept 2015 Stock Incentive Plan, the Targacept 2006 Stock Incentive Plan and the Targacept 2000 Equity Incentive Plan, as well as a standalone inducement stock option to Targacept’s former chief executive officer upon commencement of his employment with Targacept in December 2012 (together, the “Targacept Plans and Options”).

Immediately after the Merger, there were 11,416,984 shares of the Company’s common stock outstanding and, Old Catalyst equity holders beneficially owned approximately 59% of the common stock of the Company. In connection with the reverse merger, we incurred $2.0 million for related transaction costs, included in general and administrative expenses in the accompanying statements of operations.

Purchase Consideration

The purchase price for Targacept on August 20, 2015, the closing date of the Merger, was as follows (in thousands):


Estimated fair value of shares issued	$	34,664
Estimated fair value of awards assumed		1,955
Estimated fair value of redeemable convertible notes		37,073

Estimated total purchase price of net assets acquired, including assumed debt	$	73,692

Allocation of Purchase Consideration

Under the acquisition method of accounting, the total purchase price was allocated to tangible and identifiable intangible assets acquired and liabilities assumed of Targacept on the basis of their estimated fair values as of the transaction closing date on August 20, 2015.

The following table summarizes the allocation of the purchase consideration to the assets acquired and liabilities assumed based on their fair values as of August 20, 2015 (in thousands):


Cash, cash equivalents and short-term investments	$	41,154
Restricted cash		37,000
Accounts receivable		318
Prepaid and other current assets		183
Accounts payable and accrued liabilities		(4,963	)

Estimated total purchase price of net assets acquired, including assumed debt	$	73,692

The Company believes that the historical values of Targacept’s current assets and current liabilities approximate their fair values based on the short-term nature of such items.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1497-128463

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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+ Details

Convertible Notes - Related Parties

12 Months Ended

Dec. 31, 2015

Convertible Notes - Related Parties

9.	Redeemable Convertible Notes

On August 19, 2015, immediately prior to the merger, the Company issued to Targacept stockholders non-interest bearing redeemable convertible notes (the “Notes”) in the aggregate principal amount of $37.0 million, which is approximately $1.08 per share of the Company’s common stock as of the record date, or $7.56 per share after giving effect to the Reverse Stock Split (the “Pre-Closing Dividend”). The Notes do not bear interest. The principal amount of the Notes are convertible, at the option of each noteholder, into cash or into shares of the Company’s common stock at a conversion rate of $9.19 per share (after taking into account the Reverse Stock Split), and are payable in cash, if not previously redeemed or converted, at maturity on February 19, 2018, the 30-month anniversary of the closing of the issuance of the Notes.

In connection with the Pre-Closing Dividend, on August 19, 2015, Targacept entered into an indenture (the “Indenture”) with American Stock Transfer & Trust Company, LLC, as trustee, and an escrow agreement with American Stock Transfer & Trust Company, LLC and Delaware Trust Company, LLC, as escrow agent, under which $37.0 million, which represented the initial principal amount of the convertible notes, was deposited in a segregated escrow account for the benefit of the holders of the notes in order to facilitate the payment of the notes upon redemption or at maturity (the amount of such deposit together with interest accrued and capitalized thereon, the “Escrow Funds”). The Notes are the Company’s secured obligation, and the Indenture does not limit its other indebtedness, secured or unsecured.

Holders of the Notes may submit conversion notices, which are irrevocable, instructing the trustee to convert such the Notes into shares of the common stock at a conversion price of $9.19 per share. Following each conversion date, the Company will issue the number of whole shares of common stock issuable upon conversion as promptly as practicable (and in any event within 10 business days). The trustee will in turn release to the Company the respective amount of restricted cash to cover the stock issuance.

The conversion to common stock feature of the Notes was determined to be a derivative liability requiring bifurcation and separate accounting. The fair value of such conversion feature at issuance was determined to be $1.5 million. The Company estimated the fair value of the conversion option using the Black-Scholes option-pricing valuation model with the following assumptions: expected term of 2.25 years, risk-free interest rate of 0.84%, expected volatility of 70.0%, anticipated future exchange rate of the Notes and a dividend yield of 0%.

The bifurcation of the derivative liability from the estimated fair value of the Notes of $37.1 million at issuance resulted in a debt discount of $1.4 million. The Company elected to accrete the entire debt discount as interest expense immediately subsequent to the merger. In addition, changes in the fair value of the derivative liability will be recorded within interest and other income in the consolidated statement of operations. The Company will remeasure the derivative liability to fair value until the earlier of the conversion, redemption or maturity of the redeemable convertible notes.

For the year ended December 31, 2015, the Company recognized interest expense of $1.4 million related to the amortization of the debt discount within interest expense on the Company’s consolidated statement of operations as the redeemable convertible notes are immediately fully redeemable at the option of the holders.

As of December 31, 2015, $3.0 million of the Notes were redeemed and $0.3 million of the Notes were converted into common stock. The Company recognized $0.1 million of gain on the extinguishment of Notes upon the redemption of the Notes during the year ended December 31, 2015.

Related Party Debt

Convertible Notes - Related Parties

8.	Convertible Notes – Related Parties

In May and June 2015, Old Catalyst issued and sold convertible promissory notes in a series of closings in the aggregate principal amount of $1.9 million to existing stockholders, together with warrants to purchase shares of either the Old Catalyst’s Series E preferred stock or the capital stock issued during the next financing. The convertible promissory notes accrued interest at a rate of 12% per annum and were to mature one year from the date of issuance.

In connection with the debt financing, Old Catalyst also issued and sold to each investor purchasing a convertible promissory note a warrant to purchase equity securities of the same type that the principal amount of the convertible promissory note issued to such investor converts into. The warrants were exercisable for up to a number of shares equal to the quotient of: (a) 25% multiplied by the principal amount of the convertible promissory note issued to such investor divided by (b) the stock purchase price equal to: (i) in the case the notes convert in connection with a financing the price per share of the securities paid by investors in such financing or (ii) in the case that the warrant shares are Series E Preferred Stock, $1.2706 per share. The purchase price for each warrant was equal to 0.1% of the principal amount of the corresponding convertible promissory note. The exercise price for the warrant shares is equal to the stock purchase price.

The Company recorded the aggregate fair value of the warrants of $0.5 million as a debt discount and convertible preferred stock warrant liability upon issuance of the convertible notes. The debt discount was being accreted as additional interest expense over the term of the convertible promissory notes. The Company estimated the fair value of the warrants using the Black-Scholes option-pricing valuation model with the following assumptions: expected term of five years, risk-free interest rate of 0.11% and 0.18%, expected volatility of 80.0% and a dividend yield of 0%.

For the year ended December 31, 2015, the Company recognized interest expense of $0.1 million related to the accrued interest and amortization of the debt discount within interest expense on the Company’s consolidated statement of operations.

In conjunction with the second closing of the Series F convertible preferred stock financing discussed in Note 10 - Convertible Preferred Stock and Warrants, Old Catalyst and the majority holders of the notes amended the notes such that the closing constituted a qualified financing and, accordingly, the total outstanding principal amount of the Notes of $1.9 million and all unpaid accrued interest of $0.03 million, were converted into 1,511,723 shares of Series F convertible preferred stock and warrants for the purchase of 372,045 shares of Series F convertible preferred stock were issued to the Notes holders in connection with the conversion of the Notes to Series F convertible preferred stock. All preferred stock and warrants were converted to common stock and warrants to purchase common stock upon the closing of the Merger.

As the recipients of the convertible promissory notes each have an equity ownership in the Company, the convertible promissory notes are considered to be a related-party transaction.

Convertible Preferred Stock and Warrants

12 Months Ended

Dec. 31, 2015

Convertible Preferred Stock and Warrants

10.

Convertible Preferred Stock and Warrants

In January 2015, Old Catalyst completed a Series F convertible preferred stock offering that generated cash proceeds of $3.3 million, net of $0.1 million of issuance costs. In the offering, Old Catalyst issued 2,623,650 shares of Series F convertible preferred stock at a price of $1.2706 per share. The Series F convertible preferred stock had a conversion rate of 1:10 such that each individual share of Series F convertible preferred stock was convertible into ten shares of common stock. In July 2015, Old Catalyst completed a second closing of a Series F convertible preferred stock financing and issued 3,164,872 shares for cash proceeds of $4.0 million, net of $0.02 million of issuance costs.

The following table sets forth the total preferred shares authorized, issued and outstanding, the liquidation value, and the carrying value per Series at December 31, 2014:


	Shares Authorized		Shares Issued and Outstanding		Liquidation Preference Per Share
Series AA		7,327,166		7,327,166	$	1.0000
Series BB		23,104,618		23,104,618	$	1.2706
Series BB-1		5,978,477		5,978,477	$	1.5054
Series CC		46,429,980		46,429,980	$	1.2706
Series D		629,630		629,630	$	6.3530
Series E		5,000,000		3,935,140	$	2.5412

		88,469,871		87,405,011

As discussed in Note 7 - Reverse Merger, all outstanding shares of Old Catalyst’s convertible preferred stock and warrants to purchase convertible preferred stock were converted into shares of the Company’s common stock and warrants to purchase common stock upon completion of the merger.

The rights, privileges, and preferences of the convertible preferred stock were as follows:

Voting

Each share of convertible preferred stock was entitled to voting rights equivalent to the number of shares of common stock into which each share would have been converted. Each share of common stock was entitled to one vote.

Conversion

Each share of convertible preferred stock was convertible at the holder’s option at any time into common stock, subject to adjustment for anti-dilution. The conversion price for Series AA convertible preferred stock was $1.00 per share, for Series BB convertible preferred stock was $1.2706 per share, for Series BB-1 convertible preferred stock was $1.3843 per share, and for Series CC, Series D and Series E convertible preferred stock was $1.2706 per share. Conversion would have been automatic upon the closing of an underwritten public offering with an offering price of at least $3.8118 per share and aggregate gross proceeds of at least $40 million, or upon the written consent of holders of at least 66.67% of the then-outstanding convertible preferred stock.

Warrants

Old Catalyst previously issued (i) warrants to purchase shares of Series A convertible preferred stock in 2005 in connection with a loan, (ii) warrants to purchase shares of Series E convertible preferred stock in 2014 in connection with the issuance of Series E convertible preferred stock, and (iii) warrants to purchase shares of Series F convertible preferred stock in 2015 in connection with the issuance of convertible promissory notes. In connection with the merger, such warrants were assumed by the Company and are now exercisable, respectively, (i) at any time until the 7-year anniversary of the merger for an aggregate of 1,289 shares of the Company’s common stock at an exercise price of $26.18 per share, (ii) at any time until the 5-year anniversary of the original date of issuance for an aggregate of 37,554 shares of the Company’s common stock at an exercise price of $33.27 per share, and (iii) at any time until the 5-year anniversary of the original date of issuance for an aggregate of 142,111 shares of the Company’s common stock at an exercise price of $3.33 per share, for a combined total of 180,954 shares of common stock issuable upon the exercise of warrants outstanding with a combined weighted average exercise price of $9.70 per share.

Stock Based Compensation

12 Months Ended

Dec. 31, 2015

Stock Based Compensation

11.

Stock Based Compensation

As discussed in Note 7 - Reverse Merger, the Company assumed all of the outstanding options, whether or not vested, under the Catalyst Plan, all of the standalone options of Old Catalyst that were not issued under the Catalyst Plan, whether or not vested, outstanding immediately prior to the Merger, with such options henceforth representing the right to purchase that number of shares of the Company’s common stock equal to 0.0382 multiplied by the number of shares of Old Catalyst common stock previously represented by such options. For accounting purposes, however, the Company is instead deemed to have assumed all of the Targacept Plans and Options (outstanding immediately prior to the Merger (together with the Catalyst Plan and the standalone Catalyst options, the “Plans”). No additional grants were made from the Plans on or after the Merger Effective Date.

Immediately prior to the Merger Effective Date:

•

The Catalyst Plan expired effective January 2014, with options for 230,997 shares remaining outstanding. Such options were assumed in the Merger pursuant to the Merger Agreement.

•

35,545 standalone options of Old Catalyst were outstanding. Such options were assumed in the Merger pursuant to the Merger Agreement.

•

The Targacept 2006 Plan (the “2006 Plan”) had 1,420,823 options outstanding and 591,757 shares available for issuance. The outstanding options under the 2006 Plan were assumed in the Merger for accounting purposes, and the shares available for issuance were contributed to the Targacept 2015 Stock Incentive Plan (the “Targacept 2015 Plan”).

The 2015 Plan

As of August 18, 2015, Targacept shareholders approved the Targacept 2015 Plan. The Targacept 2015 Plan had no shares authorized for issuance as of the approval date. Upon the Merger, the Targacept 2015 Plan was assumed by the Company for accounting purposes and 591,757 unused and available shares remaining in the Targacept 2006 Plan were contributed to the Targacept 2015 Plan. In addition, following the Merger, any option shares canceled or expired in the Plans (as defined above) are automatically, and without action by the company, contributed to the Targacept 2015 Plan and become available for issuance under the Targacept 2015 Plan.

The Targacept 2015 Plan was amended and restated on October 14, 2015, to reflect, among other things, rename it as the Catalyst Biosciences, Inc. 2015 Stock Incentive Plan (As Amended and Restated Effective October 14, 2015) and to reflect the Company’s seven-for-one reverse stock split, and the plan was further amended on December 14, 2015 to increase certain award limitations provided therein (as so amended, the “2015 Plan” referred to in this 10-K).

As of December 31, 2015, 103,129 shares of common stock were available for future grant and options to purchase shares of common stock were outstanding under the 2015 Stock Plan, as amended.

The following table summarizes stock option activity under the plans including stock options granted to non-employees, and related information:


	Number of Shares Underlying Outstanding Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (thousands)
Outstanding — December 31, 2012		193,177		$	8.12		6.29		6.29
Options granted		57,313		$
Options exercised		—		$	11.52
Options forfeited		(4,641	)	$	9.45

Outstanding — December 31, 2013		245,849		$	8.88		6.18
Options granted		12,415		$	7.59
Options exercised		(5,730	)	$	4.36
Options forfeited		(2,279	)	$	3.82

Outstanding — December 31, 2014		250,255		$	8.96		5.51
Options assumed in merger⁽¹⁾		1,420,823		$	15.16		4.01
Options granted		675,585		$	2.98		9.81
Options exercised		(3,820	)	$	3.38
Options forfeited		(36,547	)	$	8.48
Options canceled		(106,787	)	$	47.20

Outstanding — December 31, 2015		2,199,509		$	9.84		4.51	$	11.06

Exercisable — December 31, 2015		1,560,477		$	11.99		2.37	$	8.08

Vested and expected to vest — December 31, 2015		2,139,323		$	9.99		4.37


Shares Available to be granted — December 31, 2015		103,129

(1)

In connection with the merger, the Company assumed stock options covering an aggregate of 1,420,823 shares of common stock. The company also assumed 2,856 shares of Restricted Stock Awards which vest in two equal annual installments beginning on December 31, 2015 and fully vesting on December 31, 2016. Total stock based compensation related to these restricted stock awards was $6,052 for year ended December 31, 2015.

Total stock-based compensation recognized was as follows (in thousands):


	Year Ended December 31,
	2015		2014		2013
Research and development	$	95	$	81	$	127
General and administrative		231		163		171

Total stock-based compensation	$	326	$	244	$	298

The estimated grant-date fair value-based measurements of the employee stock options were calculated using the Black-Scholes valuation model, based on the following weighted-average assumptions in the years ended December 31, 2015, 2014 and 2013:


	Year Ended December 31,
	2015			2014			2013
Expected term		5.56 years			5.14 years			5.98 years
Expected volatility		68.64	%		64.62	%		78.15	%
Risk-free interest rate		1.34	%		1.61	%		1.06	%
Expected dividend yield		0	%		0	%		0	%

Expected Term. Under the Company’s stock option plans, the expected term of options granted is determined using the simplified method which calculates expected term as the midpoint between the vesting date and the expiration date for each award.

Expected Volatility. Since the Company was a private entity prior to the merger in August 2015 with no historical data regarding the volatility of its common stock, the expected volatility used is based on the volatility of similar publicly traded entities, referred to as “guideline” companies.

Risk-Free Interest Rate. The risk-free rate is based on U.S. Treasury zero-coupon issues with remaining terms similar to the expected term of the options.

Expected Dividend Yield. The Company has never declared or paid any cash dividends and does not plan to pay cash dividends in the foreseeable future, and, therefore, assumed an expected dividend yield of zero.

As of December 31, 2015, the Company had unrecognized employee stock-based compensation expense of $1.6 million, related to unvested stock awards, which is expected to be recognized over an estimated weighted-average period of 3.39 years.

Options Granted to Nonemployees

During the years ended December 31, 2015, 2014 and 2013, options to purchase 19,760, 12,415 and 5,717 shares, respectively, of common stock were issued to consultants that vest over one to four years with a weighted-average exercise price of $6.52, $7.60 and $11.51 per share, respectively. During the years ended December 31, 2015, 2014 and 2013, the Company recorded stock-based compensation expense attributable to these nonemployee stock awards of $0.04 million, $0.1 million and $0.1 million, respectively.

The estimated grant-date fair values of the nonemployee stock options were determined using the Black-Scholes valuation model and the following assumptions:


	Year Ended December 31,
	2015			2014			2013
Risk-free interest rate		1.30	%		1.61	%		1.06	%
Expected volatility		69.98	%		64.62	%		78.00	%
Expected dividend yield		0	%		0	%		0	%
Weighted-average contractual term		5.64 years			5.14 years			5.98 years

Income Taxes

12 Months Ended

Dec. 31, 2015

Income Taxes

12.

Income Taxes

The Company has incurred cumulative net operating losses since inception and, consequently, has not recorded any income tax expense for the years ended December 31, 2015, 2014 and 2013 due to its net operating loss position.

The reconciliation of the federal statutory income tax rate to the Company’s effective tax rate for the years ended December 31, 2015, and 2014 are as follows:


	Year Ended December 31,
	2015			2014
Tax at statutory federal rate		34.00	%		34.00	%
State Tax (benefit)—net of federal benefit		1.33	%		-3.24	%
Permanent differences		-8.00	%		1.83	%
R&D Credits		11.59	%		1.97	%
Derecognition due to Sec. 382 and 383 Limitations		-240.87	%		0.00	%
Change in Valuation Allowance		204.17	%		-34.25	%
Other		-2.22	%		-0.31	%

Effective tax rate		0.00	%		0.00	%

Significant components of the Company’s deferred tax assets as of December 31, 2015 and 2014 consist of the following (in thousands):


	Year Ended December 31,
	2015			2014
Deferred tax assets:
Accruals and reserves	$	1,285		$	1,382
Net Operating Loss Carry forward		17,650			44,083
R&D Tax Credit Carry forward		2,625			6,467
Fixed and intangible assets		95			43
Valuation Allowance		(21,655	)		(51,975	)

Net deferred tax assets:	$	—		$	—

Based on the available objective evidence at December 31, 2015, the Company does not believe it is more likely than not that the net deferred tax assets will be fully realizable. Accordingly, the Company has provided a full valuation allowance against its net deferred tax assets at December 31, 2015 and 2014.

As of December 31, 2015, after consideration of certain limitations (see below), the Company had approximately $44.8 million federal and $41.6 million state net operating loss carry forwards (“NOL”) available to reduce future taxable income which, if unused, will begin to expire in 2025 for federal and 2016 for state tax purposes. Of the above NOL amounts, $0.02 million for federal and state purposes relate to windfall stock based compensation deductions which, when utilized, will be credited to equity.

As of December 31, 2015, the Company also had tax credit carry forwards available to offset future tax liabilities of approximately $5.2 million for state purposes. The state tax credit does not expire.

If the Company experiences a greater than 50 percentage point aggregate change in ownership over a three-year period (a Section 382 ownership change), utilization of its pre-change NOL carry forwards are subject to annual limitation under Section 382 of the Internal Revenue Code (California has similar provisions). The annual limitation is determined by multiplying the value of the Company’s stock at the time of such ownership change by the applicable long-term tax-exempt rate. Such limitations may result in expiration of a portion of the NOL carry forwards before utilization. The Company has determined that ownership changes occurred on December 31, 2007 and August 20, 2015. Approximately $78.5 million and $61.9 million of the NOLs will expire unutilized for federal and California purposes, respectively. The Company has derecognized NOL related DTAs in the tax affected amounts of $26.7 million and $3.3 million for federal and California purposes, respectively.

All of the federal R&D credits could expire unutilized as well, whereas none of the California R&D credits are subject to expiration. Approximately $5.6 million of gross federal R&D credit-related DTAs were derecognized due to the Section 383 limitation. The ability of the Company to use its remaining NOL carry forwards may be further limited if the Company experiences a Section 382 ownership change as a result of future changes in its stock ownership.

Accounting for Uncertainty in Income Taxes

The Company only recognizes tax benefits if it is more likely than not that they will be sustained upon audit by the relevant tax authority based upon their technical merits. An uncertain tax position will not be recognized if it has less than a 50% likelihood of being sustained.

The Company had approximately $1.3 million and $2.6 million of unrecognized tax benefits as of both December 31, 2015 and 2014. As the Company has a full valuation allowance on its deferred tax assets, the unrecognized tax benefits have reduced the deferred tax assets and the valuation allowance in the same amount. The Company does not expect the amount of unrecognized tax benefits to materially change in the next twelve months. A reconciliation of the beginning and ending balance of the unrecognized tax benefits is as follows (in thousands):


Beginning Balance at January 1, 2014	$	2,517
Increase/(Decrease) of unrecognized tax benefits taken in prior years		—
Increase/(Decrease) of unrecognized tax benefits related to current year		53

Ending Balance at December 31, 2014	$	2,570


Beginning Balance at January 1, 2015	$	2,570
Increase/(Decrease) of unrecognized tax benefits taken in prior years		(1,347	)
Increase/(Decrease) of unrecognized tax benefits related to current year		91

Ending Balance at December 31, 2015	$	1,314

The Company files income tax returns in the United States and California. The Company is not currently under examination by income tax authorities in federal, state or other jurisdictions. As of December 31, 2015 and 2014, the Company had no uncertain tax positions which affected its financial position and its results of operations or its cash flow, and will continue to evaluate for uncertain positions in the future. The open tax years for the Company are December 31, 2012 through December 31, 2015 and are subject to examination by the IRS and other various taxing authorities, generally for three years after tax returns are filed.

Collaborations

12 Months Ended

Dec. 31, 2015

Collaborations

13.

Collaborations

Pfizer

On August 20, 2013 the Company and Pfizer entered into an amendment to the Factor VIIa collaboration agreement whereby the companies agreed to provide specific mutual releases and covenants and modify certain milestone payment schedules in the agreement. Per the amendment, Pfizer agreed to make two non-refundable $1.5 million annual license maintenance payments to the Company, payable on August 1, 2014 and August 1, 2013. The annual license maintenance payments received were being amortized to contract revenue over the estimated expected performance period under the arrangement, which the Company estimated was to the end August 1, 2015.

On April 2, 2015, Pfizer notified the Company that it was exercising its right to terminate in its entirety the collaboration agreement. The termination became effective 60 days after the Company’s receipt of the termination notice. On June 1, 2015, the license and certain rights under the research and license agreement terminated and reverted back to the Company. Pfizer is in the process of transferring clinical trial data, regulatory documentation and related technology under the research and license agreement to the Company. The Company plans to continue clinical development of this product candidate. The Company revised the expected period of performance to end on June 1, 2015, which was the effective termination of all performance obligations of the Company under the research and license agreement. Accordingly, all deferred revenue was recognized through June 1, 2015.

Contract revenue related to the agreement with Pfizer was $1.3 million, $1.4 million and $0.3 million during the years ended December 31, 2015, 2014 and 2013, respectively. The deferred revenue balance related to the Pfizer collaboration was zero and $1.3 million as of December 31, 2015 and 2014, respectively.

ISU Abxis

On June 16, 2013, the Company entered into a license and collaboration agreement with ISU Abxis, whereby the Company licensed its proprietary human Factor IX products to ISU Abxis for initial development in South Korea. Under the terms of the agreement, ISU Abxis is responsible for development and manufacturing of the licensed products through Phase 1/2 clinical trials. Until the completion of Phase 1/2 development, ISU Abxis also has a right of first refusal with respect to commercialization rights for the licensed products in South Korea. The Company has the sole rights and responsibility for worldwide development, manufacture and commercialization of Factor IX products after Phase 1/2 development, unless ISU Abxis has exercised its right of first refusal regarding commercialization rights in South Korea, in which case the Company’s rights are in the entire world excluding South Korea. ISU’s rights will also terminate in the event that the Company enters into a license agreement with another party to develop, manufacture and commercialize Factor IX products in at least two major market territories.

ISU Abxis paid the Company an up-front signing fee of $1.75 million and is obligated to pay to the Company contingent milestone-based payments on the occurrence of certain defined development events, and reimbursement for a portion of the Company’s costs relating to intellectual property filings and maintenance thereof on products. The Company is obligated to pay ISU Abxis a percentage of all net profits it receives from collaboration products.

Contract revenue of $0.4 million, $0.4 million and $0.1 million for the years ended December 31, 2015, 2014 and 2013, respectively, reflected the amortization of the up-front fee over the estimated period of the Company’s performance obligations under the agreement, which was assessed to be four years beginning in September 2013 when the agreement was executed. The deferred revenue balance related to the ISU Abxis collaboration was $0.7 million and $1.2 million as of December 31, 2015 and 2014, respectively.

Net Loss per Common Share

12 Months Ended

Dec. 31, 2015

Net Loss per Common Share

14.

Net Loss per Common Share

The following table sets forth the computation of the basic and diluted net loss per common share during the years ended December 31, 2015, 2014 and 2013 (in thousands, except share and per share data):


	Year Ended December 31,
	2015			2014			2013
Net loss	$	(14,762	)	$	(6,613	)	$	(9,966	)

Weighted-average number of shares used in computing net loss per share, basic and diluted		4,429,093			367,586			365,214

Net loss per share, basic and diluted	$	(3.33	)	$	(17.99	)	$	(27.29	)

Since the Company was in a loss position for all periods presented, diluted net loss per share is the same as basic net loss per share for all periods as the inclusion of all potential common shares outstanding would have been anti-dilutive. Potentially dilutive securities on an as-if converted basis that were not included in the diluted per share calculations because they would be anti-dilutive were as follows:


	Year Ended December 31,
	2015		2014		2013
Convertible preferred stock		—		3,338,871		3,188,549
Options to purchase common stock		2,200,890		250,255		257,889
Convertible preferred stock warrants		—		37,580		—
Common stock warrants		180,954		1,289		1,862
Redeemable convertible notes		3,671,745		—		—

Total		6,053,589		3,627,995		3,448,300

Selected Quarterly Financial Data (unaudited)

12 Months Ended

Dec. 31, 2015

Selected Quarterly Financial Data (unaudited)

15.

Selected Quarterly Financial Data (unaudited)

Selected quarterly results from operations for the years ended December 31, 2015 and 2014 are as follows (in thousands, except per share amounts):


	2015 Quarter Ended
	March 31,			June 30,			September 30,			December 31,
Contract Revenue	$	672		$	860		$	109		$	109
Total operating expenses		3,704			3,060			3,994			4,794
Loss from operations		(3,033	)		(2,201	)		(3,885	)		(4,683	)
Net loss		(2,858	)		(1,724	)		(5,051	)		(5,129	)
Net loss per share– basic and diluted	$	(7.67	)	$	(4.60	)	$	(0.93	)	$	(0.45	)


	2014 Quarter Ended
	March 31,			June 30,			September 30,			December 31,
Contract Revenue	$	297		$	297		$	547		$	672
Total operating expenses		2,160			2,507			2,185			2,470
Loss from operations		(1,863	)		(2,210	)		(1,638	)		(1,798	)
Net loss		(1,734	)		(2,075	)		(1,502	)		(1,302	)
Net loss per share– basic and diluted	$	(4.75	)	$	(5.68	)	$	(4.08	)	$	(3.51	)

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2015
Basis of Presentation	*Basis of Presentation* The accompanying consolidated financial statements include the accounts of the Company and its subsidiaries. Intercompany accounts and transactions have been eliminated in consolidation. The Company’s consolidated financial statements have been prepared in accordance with GAAP.
Use of Estimates	*Use of Estimates* The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, convertible notes and related warrants up to the date of conversion, common stock and stock-based compensation. The Company bases its estimates on various assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Cash and Cash Equivalents	*Cash and Cash Equivalents* The Company invests its excess cash in bank deposits, consisting primarily of money market mutual funds. The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents.
Restricted Cash	*Restricted Cash* Restricted cash consists primarily of certain checking, money market and certificate of deposit accounts that are: (i) pledged to or held in a segregated escrow account by the Company’s correspondent banks for the benefit of the holders of the redeemable convertible notes in order to facilitate the payment of the redeemable convertible notes upon redemption or at maturity as discussed in Note 3 - Fair Value Measurements or (ii) pledged as collateral for the Company’s corporate credit card and deposit for its facility lease.
Fair Value of Financial Instruments	*Fair Value of Financial Instruments* The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy requires that an entity maximize the use of observable inputs when estimating fair value. The fair value hierarchy includes the following three-level classification which is based on the market observability of the inputs used for estimating the fair value of the assets or liabilities being measured: Level 1 – Quoted prices in active markets for identical assets or liabilities. Level 2 – Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 – Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability. Fair value accounting is applied for all financial assets and liabilities and non-financial assets and liabilities that are recognized at fair value in the financial statements on a recurring basis (at least annually).
Property and Equipment	*Property and Equipment* Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets, which are three years for computer equipment and software, and three to seven years for laboratory and office equipment, furniture and leasehold improvements.
Intangible Assets	*Intangible Assets* Intangible assets are amortized over their useful lives in a manner that best reflects their economic benefit. Intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. We do not have any indefinite-lived intangible assets. Intangible assets represent patent rights purchased in 2009 in the amount of $0.1 million that were being amortized over their estimated useful life of 20 years, or life of the patent whichever is shorter, using the straight-line method. Annual amortization was $0 and $883 for 2015 and 2014, respectively. The Company abandoned this patent in 2014. No further amortization is necessary. The total amount amortized through 2014 was $0.02 million and the remaining $0.05 million was written off to amortization expense during 2014 in the accompanying statements of operations.
Investments	*Investments* All investments have been classified as “available-for-sale” and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments at the time of purchase and reevaluates such designation as of each balance sheet date. Unrealized gains and losses are excluded from earnings and are reported as a component of comprehensive loss. Realized gains and losses and declines in fair value determined to be other-than-temporary, if any, on available-for-sale securities are included in interest and other income. The cost of securities sold is based on the specific-identification method. Interest on short-term investments is included in interest and other income.
Derivative Liability	*Derivative Liability* The embedded redemption feature in the redeemable convertible notes, which are convertible into shares of the Company’s common stock, is accounted for as a derivative liability at its estimated fair value. The derivative is subject to remeasurement at the end of each reporting period, with changes in fair value recognized as a component of interest and other income, in the consolidated statements of operations. The Company will continue to adjust the liability for changes in fair value until the earlier of the conversion, redemption or maturity of the redeemable convertible notes.
Revenue Recognition	*Revenue Recognition* The Company enters into collaboration arrangements that may include the receipt of payments for up-front license fees, success-based milestone payments, full time equivalent based payments for research services, and royalties on any future sales of commercialized products that result from the collaborations. Revenue is recognized when the four basic criteria for revenue recognition are met: (1) persuasive evidence of an arrangement exists; (2) transfer of technology has been completed or services have been rendered; (3) the fee is fixed or determinable; and (4) collectability is reasonably assured. Revenue recognition for multiple element revenue arrangements will have deliverables associated with the arrangement divided into separate units of accounting provided that (i) a delivered item has value to the customer on a standalone basis and (ii) if the arrangement includes a general right of return relative to the delivered item, delivery or performance of the undelivered item is considered probable and substantially in the control of the vendor. As a biotechnology company with unique and specialized technological undelivered performance obligations associated with its collaborations, the Company’s multiple element arrangements most often involve deliverables and consideration that do not meet the criteria for having stand-alone value. Deliverables and performance obligations are accounted for under a single unit of accounting when they do not have stand-alone value and the related consideration is recognized as revenue over the estimated period of when the performance obligations are to be performed. The revenue is recognized on a proportional performance basis when the levels of the performance obligations under an arrangement can be reasonably estimated and on a straight-line basis when they cannot. The Company’s collaboration agreements entitle it to additional payments upon the achievement of performance-based milestones related to product development, regulatory actions and commercial events in certain geographic areas. Milestones that are not deemed probable or that are tied to counter-party performance are not included in the Company’s revenue until the performance conditions are met. If a collaborative agreement milestone is deemed to be substantive, as defined in the accounting rules, the Company is permitted to recognize revenue related to the milestone payment in its entirety. In the event milestones are deemed non-substantive, the Company recognizes, and defers if applicable, payments for the achievement of such non-substantive milestones over the estimated period of performance applicable to each collaborative agreement using the proportional performance method or on a straight-line basis, as appropriate. Amounts received under a collaborative agreement prior to satisfying revenue recognition criteria are recorded as deferred revenue in the accompanying consolidated balance sheets. Deferred revenue is recorded on the Company’s consolidated balance sheet as short-term or long-term based on its best estimate as to when such revenue will be recognized. Short-term deferred revenue consists of amounts that the Company expects to recognize as revenue in the next 12 months. Amounts that the Company expects will not be recognized prior to the next 12 months are classified as long-term deferred revenue. The Company’s performance obligations under its collaboration arrangements also consist of participation on steering committees and the performance of other research and development and business development services. The timing for satisfying these performance obligations can be difficult to estimate and can be subject to change over the course of these agreements. A change in the estimated timing for satisfying the Company’s performance obligations could change the timing and amount of revenue that the Company recognizes and records in future periods.
Research and Development Expense	*Research and Development Expenses* Research and development costs are expensed as incurred. Research and development costs consist of payroll and other personnel-related expenses, laboratory supplies and reagents, contract research and development services, and consulting costs, as well as allocations of facilities and other overhead costs. Under the Company’s collaboration agreements, certain specific expenditures are reimbursed by third parties. During the years ended December 31, 2015, 2014 and 2013, the Company recorded a reduction to research and development expenses of $0.9 million, $0.4 million, and $0.4 million, respectively related to these reimbursements.
Concentration of Credit Risk	*Concentration of Credit Risk* Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and accounts receivable, resulting from research and development pass through expense reimbursement. The Company’s accounts receivable at December 31, 2015 was $0.5 million, of which $0.4 million was due from Pfizer Inc. (“Pfizer”), and $0.1 million was due was due from our landlord CBRE for tenant improvements reimbursement. The Company has incurred no credit losses to date. The Company does not require collateral from its collaboration partners.
Income Taxes	*Income Taxes* Income taxes are computed using the liability method. Deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company follows the authoritative guidance on accounting for uncertainty in income taxes. This guidance prescribes a more-likely-than-not threshold for financial statement recognition and measurement of a tax position taken in the Company’s income tax returns. This interpretation also provides guidance on accounting for interest and penalties and associated with tax positions, accounting for income taxes in interim periods and income tax disclosures. The Company’s policy is to include penalties and interest expense related to income taxes as a component of other expense and interest expense, respectively, as necessary.
Stock-Based Compensation	*Stock-Based Compensation* The Company measures the cost of employee and director services received in exchange for an award of equity instruments based on the fair value of the award on the date of grant and recognizes the related expense over the period during which the employee or director is required to provide service in exchange for the award on a straight-line basis. The Company uses the Black-Scholes option-pricing valuation model to estimate the grant-date fair value of stock-based awards. The determination of fair value for stock-based awards on the date of grant using an option-pricing model requires management to make certain assumptions regarding a number of variables. The Company records stock-based compensation as compensation expense, net of the estimated impact of forfeited awards. The Company applies a forfeiture rate to stock-based compensation expense using historical data to estimate pre-vesting option forfeitures. The Company estimates forfeitures at the time of grant, and revises those estimates in subsequent periods if actual forfeitures differ materially from those original estimates. As such, the Company recognizes stock-based compensation expense only for those stock-based awards that are expected to vest, over their requisite service period, based on the vesting provisions of the individual grants. For nonemployee stock-based awards, the measurement date on which the fair value of the stock-based award is calculated is equal to the earlier of (i) the date at which a commitment for performance by the counterparty to earn the equity instrument is reached or (ii) the date at which the counterparty’s performance is complete. The Company recognizes stock-based compensation expense for the fair value-based measurement of the nonemployee awards using the Black Scholes option-pricing valuation model and the awards are typically subject to periodic re-measurement over the period that services are rendered.
Deferred Rent	*Deferred Rent* The Company’s facilities lease agreement provides for an escalation of rent payments each year. The Company records rent expense on a straight-line basis over the term of the lease. The difference between the amount of expense recognized and the amount of rent paid is recorded as deferred rent in the accompanying consolidated balance sheets.
Net Loss per Share	*Net Loss per Share* Basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss of the Company for all periods presented.

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2015

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following tables present the fair value hierarchy for assets and liabilities measured at fair value on a recurring basis as of December 31, 2015 and 2014 (in thousands):


	December 31, 2015
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds	$	28,927	$	—	$	—	$	28,927
Restricted cash (money market funds)⁽¹⁾		33,919		—		—		33,919
Municipal bonds		—		296		—		296
Corporate notes		—		3,106		—		3,106

Total financial assets	$	62,846	$	3,402	$	—	$	66,248

Financial liabilities:
Derivative liability	$	—	$	—	$	1,156	$	1,156

Total financial liabilities	$	—	$	—	$	1,156	$	1,156

(1)	$125,000 of restricted cash serves as collateral for the Company’s corporate credit card and deposit for its facility lease.


	December 31, 2014
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds	$	1,496	$	—	$	—	$	1,496
Restricted cash (money market funds)⁽¹⁾		50		—		—		50

Total financial assets	$	1,546	$	—	$	—	$	1,546

Financial liabilities:
Warrant for convertible preferred stock liability	$	—	$	—	$	391	$	391

Total financial liabilities	$	—	$	—	$	391	$	391

(1)	$50,000 of restricted cash serves as collateral for the Company’s corporate credit card and deposit for its facility lease.

Fair Values of Derivative Liabilities Estimated Using Black-Scholes Valuation Model


	Year Ended December 31,
	2015
Expected term		2.00 years
Expected volatility		81.7	%
Risk-free interest rate		1.06	%
Expected dividend yield		0	%

Derivative

Derivative Liability Measured at Estimated Fair Value Using Unobservable Inputs

The following table presents the activity for the derivative liability for the year ended December 31, 2015 (in thousands):


	Derivative Liability
Balance as of December 31, 2014	$	—
Issuance of derivative issued with the redeemable convertible notes		1,455
Change in fair value included in interest and other income		(242	)
Gain on extinguishment of redeemable convertible notes		(52	)
Conversion of convertible notes to common stock		(5	)

Balance as of December 31, 2015	$	1,156

Warrant

Derivative Liability Measured at Estimated Fair Value Using Unobservable Inputs

The following table presents the activity for the liability related to the warrant for convertible preferred stock for the year ended December 31, 2015 and 2014 (in thousands):


	Warrant Liability
Balance as of December 31, 2013	$	—
Issuance of preferred stock warrants		745
Change in fair value included in interest and other income		(354	)

Balance as of December 31, 2014	$	391
Issuance of preferred stock warrants		474
Change in fair value included in interest and other income		(91	)
Reclassification of warrant liability to equity upon conversion to common stock warrants		(774	)

Balance as of December 31, 2015	$	—

Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2015

Cash Equivalents and Short-Term and Long-Term Investments Classified as Available for Sale Securities

Cash equivalents, restricted cash and short-term and long-term investments, all of which are classified as available-for-sale securities, consisted of the following (in thousands):


December 31, 2015	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Money market funds	$	28,927	$	—	$	—		$	28,927
Restricted cash (money market funds)		33,919		—		—			33,919
Municipal bonds		295		1		—			296
Corporate notes		3,106		1		(1	)		3,106

Total financial assets	$	66,247	$	2	$	(1	)	$	66,248

Classified as:
Cash and cash equivalents								$	28,927
Restricted cash (money market funds)									33,919
Short-term investments									3,402

								$	66,248


December 31, 2014	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Money market funds	$	1,496	$	—	$	—		$	1,496
Restricted cash (money market funds)		50		—		—			50

Total financial assets	$	1,546	$	—	$	—		$	1,546

Classified as:
Cash and cash equivalents								$	1,496
Restricted cash (money market funds)									50

								$	1,546

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2015

Schedule of Property and equipment

Property and equipment consisted of the following (in thousands):


	December 31,
	2015			2014
Laboratory and office equipment	$	4,458		$	5,027
Furniture		321			311
Leasehold improvements		1,591			1,515
Computer equipment		21			285
Software		8			422

		6,399			7,560
Less accumulated depreciation and amortization		(5,701	)		(6,649	)

Property and equipment, net	$	698		$	911

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2015

Expected Future Lease Payments Under All Operating Leases

Future minimum lease payments under all non-cancelable operating leases at December 31, 2015, were as follows (in thousands):


Year ending December 31,
2016	$	723
2017		745
2018		125

Total future minimum lease payments	$	1,593

Reverse Merger (Tables)

12 Months Ended

Dec. 31, 2015

Allocation of Purchase Consideration to Assets Acquired and Liabilities Assumed Based on Fair Values

The following table summarizes the allocation of the purchase consideration to the assets acquired and liabilities assumed based on their fair values as of August 20, 2015 (in thousands):


Cash, cash equivalents and short-term investments	$	41,154
Restricted cash		37,000
Accounts receivable		318
Prepaid and other current assets		183
Accounts payable and accrued liabilities		(4,963	)

Estimated total purchase price of net assets acquired, including assumed debt	$	73,692

Targacept

Schedule of Purchase Price

The purchase price for Targacept on August 20, 2015, the closing date of the Merger, was as follows (in thousands):


Estimated fair value of shares issued	$	34,664
Estimated fair value of awards assumed		1,955
Estimated fair value of redeemable convertible notes		37,073

Estimated total purchase price of net assets acquired, including assumed debt	$	73,692

Convertible Preferred Stock and Warrants (Tables)

12 Months Ended

Dec. 31, 2015

Authorized, Issued and Outstanding, Liquidation Value and Carrying Value of Preferred Shares

The following table sets forth the total preferred shares authorized, issued and outstanding, the liquidation value, and the carrying value per Series at December 31, 2014:


	Shares Authorized		Shares Issued and Outstanding		Liquidation Preference Per Share
Series AA		7,327,166		7,327,166	$	1.0000
Series BB		23,104,618		23,104,618	$	1.2706
Series BB-1		5,978,477		5,978,477	$	1.5054
Series CC		46,429,980		46,429,980	$	1.2706
Series D		629,630		629,630	$	6.3530
Series E		5,000,000		3,935,140	$	2.5412

		88,469,871		87,405,011

Stock Based Compensation (Tables)

12 Months Ended

Dec. 31, 2015

Summary of Option Activity

The following table summarizes stock option activity under the plans including stock options granted to non-employees, and related information:


	Number of Shares Underlying Outstanding Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (thousands)
Outstanding — December 31, 2012		193,177		$	8.12		6.29		6.29
Options granted		57,313		$
Options exercised		—		$	11.52
Options forfeited		(4,641	)	$	9.45

Outstanding — December 31, 2013		245,849		$	8.88		6.18
Options granted		12,415		$	7.59
Options exercised		(5,730	)	$	4.36
Options forfeited		(2,279	)	$	3.82

Outstanding — December 31, 2014		250,255		$	8.96		5.51
Options assumed in merger⁽¹⁾		1,420,823		$	15.16		4.01
Options granted		675,585		$	2.98		9.81
Options exercised		(3,820	)	$	3.38
Options forfeited		(36,547	)	$	8.48
Options canceled		(106,787	)	$	47.20

Outstanding — December 31, 2015		2,199,509		$	9.84		4.51	$	11.06

Exercisable — December 31, 2015		1,560,477		$	11.99		2.37	$	8.08

Vested and expected to vest — December 31, 2015		2,139,323		$	9.99		4.37


Shares Available to be granted — December 31, 2015		103,129

(1)

Summary of Stock-Based Compensation Recognized

Total stock-based compensation recognized was as follows (in thousands):


	Year Ended December 31,
	2015		2014		2013
Research and development	$	95	$	81	$	127
General and administrative		231		163		171

Total stock-based compensation	$	326	$	244	$	298

Employee Stock Option

Estimated Grant-Date Fair Value-Based Measurements, Employee Stock Options


	Year Ended December 31,
	2015			2014			2013
Expected term		5.56 years			5.14 years			5.98 years
Expected volatility		68.64	%		64.62	%		78.15	%
Risk-free interest rate		1.34	%		1.61	%		1.06	%
Expected dividend yield		0	%		0	%		0	%

Non Employee Stock Option

Estimated Grant-Date Fair Value-Based Measurements, Employee Stock Options

The estimated grant-date fair values of the nonemployee stock options were determined using the Black-Scholes valuation model and the following assumptions:


	Year Ended December 31,
	2015			2014			2013
Risk-free interest rate		1.30	%		1.61	%		1.06	%
Expected volatility		69.98	%		64.62	%		78.00	%
Expected dividend yield		0	%		0	%		0	%
Weighted-average contractual term		5.64 years			5.14 years			5.98 years

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Reconciliation of Federal Income Tax Rate to Company's Effective Tax Rate

The reconciliation of the federal statutory income tax rate to the Company’s effective tax rate for the years ended December 31, 2015, and 2014 are as follows:


	Year Ended December 31,
	2015			2014
Tax at statutory federal rate		34.00	%		34.00	%
State Tax (benefit)—net of federal benefit		1.33	%		-3.24	%
Permanent differences		-8.00	%		1.83	%
R&D Credits		11.59	%		1.97	%
Derecognition due to Sec. 382 and 383 Limitations		-240.87	%		0.00	%
Change in Valuation Allowance		204.17	%		-34.25	%
Other		-2.22	%		-0.31	%

Effective tax rate		0.00	%		0.00	%

Components of the Company's Deferred Tax Assets (Liabilities)

Significant components of the Company’s deferred tax assets as of December 31, 2015 and 2014 consist of the following (in thousands):


	Year Ended December 31,
	2015			2014
Deferred tax assets:
Accruals and reserves	$	1,285		$	1,382
Net Operating Loss Carry forward		17,650			44,083
R&D Tax Credit Carry forward		2,625			6,467
Fixed and intangible assets		95			43
Valuation Allowance		(21,655	)		(51,975	)

Net deferred tax assets:	$	—		$	—

Unrecognized Tax Benefits

A reconciliation of the beginning and ending balance of the unrecognized tax benefits is as follows (in thousands):


Beginning Balance at January 1, 2014	$	2,517
Increase/(Decrease) of unrecognized tax benefits taken in prior years		—
Increase/(Decrease) of unrecognized tax benefits related to current year		53

Ending Balance at December 31, 2014	$	2,570


Beginning Balance at January 1, 2015	$	2,570
Increase/(Decrease) of unrecognized tax benefits taken in prior years		(1,347	)
Increase/(Decrease) of unrecognized tax benefits related to current year		91

Ending Balance at December 31, 2015	$	1,314

Net Loss per Common Share (Tables)

12 Months Ended

Dec. 31, 2015

Basic and Diluted Net Loss Per Share


	Year Ended December 31,
	2015			2014			2013
Net loss	$	(14,762	)	$	(6,613	)	$	(9,966	)

Weighted-average number of shares used in computing net loss per share, basic and diluted		4,429,093			367,586			365,214

Net loss per share, basic and diluted	$	(3.33	)	$	(17.99	)	$	(27.29	)

Anti-dilutive Security not Included In Diluted per Share Calculations


	Year Ended December 31,
	2015		2014		2013
Convertible preferred stock		—		3,338,871		3,188,549
Options to purchase common stock		2,200,890		250,255		257,889
Convertible preferred stock warrants		—		37,580		—
Common stock warrants		180,954		1,289		1,862
Redeemable convertible notes		3,671,745		—		—

Total		6,053,589		3,627,995		3,448,300

Selected Quarterly Financial Data (unaudited) (Tables)

12 Months Ended

Dec. 31, 2015

Quarterly Financial Data

Selected quarterly results from operations for the years ended December 31, 2015 and 2014 are as follows (in thousands, except per share amounts):


	2015 Quarter Ended
	March 31,			June 30,			September 30,			December 31,
Contract Revenue	$	672		$	860		$	109		$	109
Total operating expenses		3,704			3,060			3,994			4,794
Loss from operations		(3,033	)		(2,201	)		(3,885	)		(4,683	)
Net loss		(2,858	)		(1,724	)		(5,051	)		(5,129	)
Net loss per share– basic and diluted	$	(7.67	)	$	(4.60	)	$	(0.93	)	$	(0.45	)


	2014 Quarter Ended
	March 31,			June 30,			September 30,			December 31,
Contract Revenue	$	297		$	297		$	547		$	672
Total operating expenses		2,160			2,507			2,185			2,470
Loss from operations		(1,863	)		(2,210	)		(1,638	)		(1,798	)
Net loss		(1,734	)		(2,075	)		(1,502	)		(1,302	)
Net loss per share– basic and diluted	$	(4.75	)	$	(5.68	)	$	(4.08	)	$	(3.51	)

Nature of Operations - Additional Information (Detail) $ in Thousands		12 Months Ended
	Aug. 20, 2015	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Nov. 30, 2015 USD ($)
Organization and Nature of Operations [Line Items]
Accumulated deficit		$ 131,037	$ 116,275
Cash, cash equivalents and short-term investments		32,500
Research and development		5,958	$ 5,267	$ 6,557
Letter of Agreement (LoA)
Organization and Nature of Operations [Line Items]
Project commitment amount					$ 1,500
Prepaid amount					$ 1,100
Research and development		$ 100
Targacept
Organization and Nature of Operations [Line Items]
Stock split ratio	7

- Definition

Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable.

+ References + Details

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2009
Significant Accounting Policies [Line Items]
Patent rights				$ 100,000
Reduction to research and development expense	$ 900,000	$ 400,000	$ 400,000
Accounts receivable	$ 492,000	95,000
Patents
Significant Accounting Policies [Line Items]
Intangible assets amortization period	20 years, or life of the patent whichever is shorter
Amortization of intangible assets	$ 0	883
Accumulated amortization intangible assets		20,000
Intangible assets written off to amortization expense		$ 50,000
Computer equipment
Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Laboratory and office equipment \| Minimum
Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Laboratory and office equipment \| Maximum
Significant Accounting Policies [Line Items]
Estimated useful lives	7 years
Furniture \| Minimum
Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Furniture \| Maximum
Significant Accounting Policies [Line Items]
Estimated useful lives	7 years
Leasehold improvements \| Minimum
Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Leasehold improvements \| Maximum
Significant Accounting Policies [Line Items]
Estimated useful lives	7 years
Pfizer Inc
Significant Accounting Policies [Line Items]
Accounts receivable	$ 400,000
ISU Abxis
Significant Accounting Policies [Line Items]
Accounts receivable	$ 100,000

Assets and Liabilities Measured at Fair Value (Detail) - USD ($)
$ in Thousands

Dec. 31, 2015

Dec. 31, 2014

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

$ 66,248

$ 1,546

Liabilities, fair value

1,156

391

Restricted cash

33,794

Municipal Bonds

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

296

Corporate Notes

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

3,106

Money Market Funds

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

28,927

1,496

Restricted cash (money market funds)

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

33,919

^[1]

^[2]

Warrant For Convertible Preferred Stock Liability

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Liabilities, fair value

391

Collateral for Corporate Credit Card and Deposit

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Restricted cash

125

Derivative liability

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Liabilities, fair value

1,156

Fair Value, Inputs, Level 1

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

62,846

1,546

Fair Value, Inputs, Level 1 | Money Market Funds

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

28,927

1,496

Fair Value, Inputs, Level 1 | Restricted cash (money market funds)

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

33,919

^[1]

^[2]

Fair Value, Inputs, Level 2

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

3,402

Fair Value, Inputs, Level 2 | Municipal Bonds

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

296

Fair Value, Inputs, Level 2 | Corporate Notes

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

3,106

Fair Value, Inputs, Level 3

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Liabilities, fair value

1,156

391

Fair Value, Inputs, Level 3 | Warrant For Convertible Preferred Stock Liability

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Liabilities, fair value

$ 391

Fair Value, Inputs, Level 3 | Derivative liability

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Liabilities, fair value

$ 1,156

[1]	$125,000 of restricted cash serves as collateral for the Company's corporate credit card and deposit for its facility lease.
[2]	$50,000 of restricted cash serves as collateral for the Company's corporate credit card and deposit for its facility lease.

Liability Related to Warrant for Convertible Preferred Stock Measured at Estimated Fair Value Using Unobservable Inputs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 391
Issuance of preferred stock warrants	474	$ 745
Change in fair value included in interest and other income	(91)	(354)
Reclassification of warrant liability to equity upon conversion to common stock warrants	$ (774)
Ending Balance		$ 391

Derivative Liability Measured at Estimated Fair Value Using Unobservable Inputs (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Issuance of derivative issued with the redeemable convertible notes	$ 1,455
Change in fair value included in interest and other income	(242)
Gain on extinguishment of redeemable convertible notes	(52)
Conversion of convertible notes to common stock	(5)
Balance as of December 31, 2015	$ 1,156

Fair Values of Derivative Liabilities Estimated Using Black-Scholes Valuation Model (Detail) - Derivative liability	12 Months Ended
	Dec. 31, 2015
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Expected term	2 years
Expected volatility	81.70%
Risk-free interest rate	1.06%
Expected dividend yield	0.00%

Cash Equivalents and Short-Term and Long-Term Investments Classified as Available for Sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 66,247	$ 1,546
Gross Unrealized Gains	2
Gross Unrealized Losses	(1)
Estimated Fair Value	66,248	1,546
Money Market Funds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	28,927	1,496
Estimated Fair Value	28,927	1,496
Money Market Funds \| Restricted cash (money market funds)
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	33,919	50
Estimated Fair Value	33,919	50
Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	28,927	$ 1,496
Municipal Bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	295
Gross Unrealized Gains	1
Estimated Fair Value	296
Corporate Notes
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,106
Gross Unrealized Gains	1
Gross Unrealized Losses	(1)
Estimated Fair Value	3,106
Short-Term Investments
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	$ 3,402

Financial Instruments - Additional Information (Detail)	12 Months Ended
Financial Instruments - Additional Information (Detail)	Dec. 31, 2015 USD ($)
Financial Instrument [Line Items]
Significant realized gains or losses on available-for-sale securities	$ 0
Maximum
Financial Instrument [Line Items]
Available for sale securities contractual maturities	1 year

Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 6,399	$ 7,560
Less accumulated depreciation and amortization	(5,701)	(6,649)
Property and equipment, net	698	911
Software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	8	422
Laboratory and office equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	4,458	5,027
Furniture
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	321	311
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	1,591	1,515
Computer equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 21	$ 285

Property and Equipment - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 0.5	$ 0.7	$ 1.0

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands			12 Months Ended
	Jun. 08, 2015	Feb. 23, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Mar. 01, 2015
Commitments and Contingencies Disclosure [Line Items]
Sub-lease expiration date		Aug. 31, 2015
Sub-lease extend date	Feb. 27, 2018
Operating lease rent expense			$ 700	$ 1,000	$ 1,000
License fees payable					$ 100
Letter of Credit
Commitments and Contingencies Disclosure [Line Items]
Letter of credit amount						$ 130	$ 50
ISU Abxis \| Maximum
Commitments and Contingencies Disclosure [Line Items]
Potential milestone payments			$ 2,000

Expected Future Lease Payments Under Operating Leases (Detail) $ in Thousands	Dec. 31, 2015 USD ($)
Operating Leased Assets [Line Items]
Year ending December 31, 2016	$ 723
Year ending December 31, 2017	745
Year ending December 31, 2018	125
Total future minimum lease payments	$ 1,593

Reverse Merger - Additional Information (Detail) $ in Millions	Dec. 31, 2015 shares	Mar. 05, 2015 USD ($) shares	Dec. 31, 2014 shares
Business Acquisition [Line Items]
Common stock, shares outstanding	11,430,085		370,944
Merger Agreement
Business Acquisition [Line Items]
Common stock exchange rate	0.0382	0.0382
Common stock, shares outstanding		11,416,984
Merger Agreement \| Old Catalysts
Business Acquisition [Line Items]
Expected ownership percentage		59.00%
Transaction related costs \| $		$ 2.0

Schedule of Purchase Price (Detail) - Targacept $ in Thousands	Aug. 20, 2015 USD ($)
Business Acquisition [Line Items]
Estimated fair value of shares issued	$ 34,664
Estimated fair value of awards assumed	1,955
Estimated fair value of redeemable convertible notes	37,073
Estimated total purchase price of net assets acquired, including assumed debt	$ 73,692

Allocation of Purchase Consideration to Assets Acquired and Liabilities Assumed Based on Fair Values (Detail) $ in Thousands	Aug. 20, 2015 USD ($)
Business Acquisition [Line Items]
Cash, cash equivalents and short-term investments	$ 41,154
Restricted cash	37,000
Accounts receivable	318
Prepaid and other current assets	183
Accounts payable and accrued liabilities	(4,963)
Estimated total purchase price of net assets acquired, including assumed debt	$ 73,692

Convertible Notes - Related Parties - Additional Information (Detail) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	Jul. 29, 2015	Jun. 30, 2015	Dec. 31, 2015	May 31, 2015
Debt Instrument [Line Items]
Interest expense related to accrued interest and amortization of debt discount			$ 100
Series F Convertible Preferred Stock
Debt Instrument [Line Items]
Convertible notes, shares issued upon conversion	1,511,723
Convertible preferred stock, warrants issued	372,045
Convertible Notes
Debt Instrument [Line Items]
Aggregate principal amount of convertible promissory notes issued and sold	$ 1,900
Convertible notes, accrued interest	$ 30
Related Party \| Warrant
Debt Instrument [Line Items]
Aggregate fair value of warrants			$ 500
Expected term			5 years
Fair value assumptions, expected volatility			80.00%
Fair value assumptions, dividend yield			0.00%
Related Party \| Warrant \| Minimum
Debt Instrument [Line Items]
Fair value assumptions, risk-free interest rate			0.11%
Related Party \| Warrant \| Maximum
Debt Instrument [Line Items]
Fair value assumptions, risk-free interest rate			0.18%
Related Party \| Convertible Notes Payable
Debt Instrument [Line Items]
Aggregate principal amount of convertible promissory notes issued and sold		$ 1,900		$ 1,900
Convertible debt interest rate		12.00%
Debt instrument maturity period		1 year
Warrants exercisable percentage			25.00%
Warrants purchase percentage			0.10%

Redeemable Convertible Notes - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Aug. 19, 2015
Debt Instrument [Line Items]
Conversion of convertible notes in to common stock, value	$ 117,647
Gain on extinguishment of redeemable convertible notes	$ 52
Convertible Notes
Debt Instrument [Line Items]
Convertible notes, total outstanding principal amount		$ 37,000
Redeemable convertible notes, conversion per share price	$ 9.19	$ 1.08
Convertible notes, maturity date	Feb. 19, 2018
Convertible notes, maturity period	30 months
Redeemable convertible notes, threshold trading days	10 days
Redeemable convertible notes, conversion feature	$ 1,500
Redeemable convertible notes, expected term	2 years 3 months
Redeemable convertible notes, risk free interest rate	0.84%
Redeemable convertible notes, expected volatility	70.00%
Redeemable convertible notes, dividend yield	0.00%
Redeemable convertible notes, estimated fair value	$ 37,100
Redeemable convertible notes, debt discount	1,400
Redeemable convertible notes, interest expense	1,400
Redeemable convertible notes, redeemed	3,000
Conversion of convertible notes in to common stock, value	$ 300
Convertible Notes \| After Reverse Stock Split
Debt Instrument [Line Items]
Redeemable convertible notes, conversion per share price	$ 9.19	$ 7.56

Convertible Preferred Stock and Warrants - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Jul. 31, 2015	Jan. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Convertible preferred stock, principal offer amount			$ 7,259	$ 4,982	$ 5,742
Convertible preferred stock voting rights			Each share of common stock was entitled to one vote.
Class of warrant or right aggregate shares			180,954
Class of warrant or right weighted average exercise price			$ 9.70
IPO
Debt Instrument [Line Items]
Percentage of outstanding convertible preferred stock			66.67%
IPO \| Minimum
Debt Instrument [Line Items]
Convertible preferred stock, shares issued per share value			$ 3.8118
Gross Proceeds			$ 40,000
Series F Convertible Preferred Stock
Debt Instrument [Line Items]
Convertible preferred stock, principal offer amount	$ 4,000	$ 3,300
Convertible preferred stock, issuance cost	$ 20	$ 100
Convertible preferred stock, shares issued	3,164,872	2,623,650
Convertible preferred stock, shares issued per share value		$ 1.2706
Convertible preferred stock, conversion rate into common stock shares		110.00%
Convertible preferred stock, conversion shares into common stock shares		10
Liquidation preference description			Each share of convertible preferred stock was convertible at the holder's option at any time into common stock, subject to adjustment for anti-dilution.
Class of warrant or right aggregate shares			142,111
Class of warrant or right exercise price			$ 3.33
Class of warrant or right expiration period			5 years
Series E Convertible Preferred Stock
Debt Instrument [Line Items]
Conversion Price Per Share			$ 1.2706
Class of warrant or right aggregate shares			37,554
Class of warrant or right exercise price			$ 33.27
Class of warrant or right expiration period			5 years
Series D Convertible Preferred Stock
Debt Instrument [Line Items]
Conversion Price Per Share			$ 1.2706
Series CC Convertible Preferred Stock
Debt Instrument [Line Items]
Conversion Price Per Share			1.2706
Series BB Convertible Preferred Stock
Debt Instrument [Line Items]
Conversion Price Per Share			1.2706
Series BB-1 Convertible Preferred Stock
Debt Instrument [Line Items]
Conversion Price Per Share			1.3843
Series AA Convertible Preferred Stock
Debt Instrument [Line Items]
Conversion Price Per Share			$ 1.00
Series A Convertible Preferred Stock
Debt Instrument [Line Items]
Class of warrant or right aggregate shares			1,289
Class of warrant or right exercise price			$ 26.18
Class of warrant or right expiration period			7 years

Schedule of Series of Shares Authorized, Issued, Outstanding and Liquidation Preference Per Share (Detail) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Shares Authorized	0	88,469,871
Shares Issued	0	87,405,011
Shares Outstanding	0	87,405,011
Series AA Convertible Preferred Stock
Class of Stock [Line Items]
Shares Authorized		7,327,166
Shares Issued		7,327,166
Shares Outstanding		7,327,166
Liquidation Preference Per Share		$ 1.0000
Series BB Convertible Preferred Stock
Class of Stock [Line Items]
Shares Authorized		23,104,618
Shares Issued		23,104,618
Shares Outstanding		23,104,618
Liquidation Preference Per Share		$ 1.2706
Series BB-1 Convertible Preferred Stock
Class of Stock [Line Items]
Shares Authorized		5,978,477
Shares Issued		5,978,477
Shares Outstanding		5,978,477
Liquidation Preference Per Share		$ 1.5054
Series CC Convertible Preferred Stock
Class of Stock [Line Items]
Shares Authorized		46,429,980
Shares Issued		46,429,980
Shares Outstanding		46,429,980
Liquidation Preference Per Share		$ 1.2706
Series D Convertible Preferred Stock
Class of Stock [Line Items]
Shares Authorized		629,630
Shares Issued		629,630
Shares Outstanding		629,630
Liquidation Preference Per Share		$ 6.3530
Series E Convertible Preferred Stock
Class of Stock [Line Items]
Shares Authorized		5,000,000
Shares Issued		3,935,140
Shares Outstanding		3,935,140
Liquidation Preference Per Share		$ 2.5412

Stock Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares	Aug. 18, 2015 shares	Mar. 05, 2015	Dec. 31, 2012 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding	2,199,509	250,255	245,849			193,177
Number of common stock available for future grant	103,129
Options, Outstanding, Weighted Average Exercise Price \| $ / shares	$ 9.84	$ 8.96	$ 8.88			$ 8.12
Stock-based compensation expense \| $	$ 326	$ 244	$ 298
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%
Non Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%
Options, Grants in Period	19,760	12,415	5,717
Options, Outstanding, Weighted Average Exercise Price \| $ / shares	$ 6.52	$ 7.60	$ 11.51
Stock-based compensation expense \| $	$ 40	$ 100	$ 100
Non Employee Stock Option \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Period	1 year
Non Employee Stock Option \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Period	4 years
Old Catalysts
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding	230,997
Old Catalysts \| Stand Alone Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding	35,545
2004 Stock Plan \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%
Unrecognized employee stock based compensation expense \| $	$ 1,600
Unrecognized employee stock based compensation expense, period for recognition	3 years 4 months 21 days
2006 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding	1,420,823
Number of common stock available for future grant	591,757
2015 Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock available for future grant	103,129			591,757
Number of shares authorized for issuance				0
Shares remaining outstanding	103,129
Amended and Restated Two Thousand Five Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of reverse stock split	Seven-for-one reverse stock split
Merger Agreement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock exchange rate	0.0382				0.0382

Summary of Option Activity (Detail) - USD ($)

12 Months Ended

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Number of Shares Underlying Outstanding Options

Number of Shares Underlying Outstanding Options, Beginning Balance

250,255

245,849

193,177

Number of Shares Underlying Outstanding Options, Options granted

675,585

12,415

57,313

Number of Shares Underlying Outstanding Options, Options exercised

(3,820)

(5,730)

Number of Shares Underlying Outstanding Options, Options forfeited

(36,547)

(2,279)

(4,641)

Number of Shares Underlying Outstanding Options, Ending Balance

2,199,509

250,255

245,849

193,177

Number of Shares Underlying Outstanding Options, Options assumed in merger

^[1]

1,420,823

Number of Shares Underlying Outstanding Options, Options canceled

(106,787)

Number of Shares Underlying Outstanding Options, Exercisable- December 31, 2015

1,560,477

Number of Shares Underlying Outstanding Options, Vested and expected to vest - December 31, 2015

2,139,323

Shares Available to be granted - December 31, 2015

103,129

Weighted- Average Exercise Price

Weighted- Average Exercise Price, Beginning Balance

$ 8.96

$ 8.88

$ 8.12

Weighted- Average Exercise Price, Options exercised, Options granted

2.98

7.59

Weighted- Average Exercise Price, Options exercised

3.38

4.36

11.52

Weighted- Average Exercise Price, Options forfeited

8.48

3.82

9.45

Weighted- Average Exercise Price, Ending Balance

9.84

$ 8.96

$ 8.88

$ 8.12

Weighted- Average Exercise Price, Options assumed in merger

^[1]

15.16

Weighted- Average Exercise Price, Options canceled

47.20

Weighted- Average Exercise Price, Exercisable - December 31, 2015

11.99

Weighted- Average Exercise Price, Vested and expected to vest - December 31, 2015

$ 9.99

Weighted Average Remaining Contractual Term

Outstanding - December 31, 2012

5 years 6 months 4 days

6 years 2 months 5 days

6 years 3 months 15 days

Options granted

9 years 9 months 22 days

Outstanding - December 31, 2015

4 years 6 months 4 days

Exercisable - December 31, 2015

2 years 4 months 13 days

Vested and expected to vest - December 31, 2015

4 years 4 months 13 days

Aggregate Intrinsic Value

Outstanding - December 31, 2012

$ 6,290

Outstanding - December 31, 2015

$ 11,060

Exercisable - December 31, 2015

$ 8,080

[1]

Summary of Option Activity (Parenthetical) (Detail)

12 Months Ended

Dec. 31, 2015

USD ($)

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of Shares Underlying Outstanding Options, Options assumed in merger

1,420,823

^[1]

Restricted Stock

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of restricted stock awards, assumed in merger

2,856

Number of Shares Underlying Outstanding Options, Options assumed in merger

1,420,823

Number of equal annual installments

Total stock based compensation | $

$ 6,052

[1]

Summary of Stock-Based Compensation Recognized (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 326	$ 244	$ 298
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	95	81	127
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 231	$ 163	$ 171

Fair Values of Stock Options Estimated Using Black-Scholes Valuation Model (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Black Scholes Method Used [Line Items]
Expected term	5 years 6 months 22 days	5 years 1 month 21 days	5 years 11 months 23 days
Expected volatility	68.64%	64.62%	78.15%
Risk-free interest rate	1.34%	1.61%	1.06%
Expected dividend yield	0.00%	0.00%	0.00%
Non Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Black Scholes Method Used [Line Items]
Expected term	5 years 7 months 21 days	5 years 1 month 21 days	5 years 11 months 23 days
Expected volatility	69.98%	64.62%	78.00%
Risk-free interest rate	1.30%	1.61%	1.06%
Expected dividend yield	0.00%	0.00%	0.00%

Reconciliation of Statutory Federal Income Tax (benefit) Rate to Company's Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Income Tax Examination [Line Items]
Tax at statutory federal rate	34.00%	34.00%
State Tax (benefit)-net of federal benefit	1.33%	(3.24%)
Permanent differences	(8.00%)	1.83%
R&D Credits	11.59%	1.97%
Derecognition due to Sec. 382 and 383 Limitations	(240.87%)	0.00%
Change in Valuation Allowance	204.17%	(34.25%)
Other	(2.22%)	(0.31%)
Effective tax rate	0.00%	0.00%

Components of Company's Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Accruals and reserves	$ 1,285	$ 1,382
Net Operating Loss Carry forward	17,650	44,083
R&D Tax Credit Carry forward	2,625	6,467
Fixed and intangible assets	95	43
Valuation Allowance	(21,655)	(51,975)
Net deferred tax assets:	$ 0	$ 0

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2007
Income Tax [Line Items]
Gross federal R&D tax credit-related DTAs derecognized	$ 5,600
Unrecognized tax benefit	1,314	$ 2,570	$ 2,517
Windfall Stock Based Compensation Deductions
Income Tax [Line Items]
Net operating loss carryforwards	20
Federal Income Tax
Income Tax [Line Items]
Net operating loss carryforwards	$ 44,800			$ 78,500
Net operating loss carry forwards expire period	Dec. 31, 2025
Net operating loss carryforward,derecognized				$ 26,700
State Income Tax
Income Tax [Line Items]
Net operating loss carryforwards	$ 41,600
Net operating loss carry forwards expire period	Dec. 31, 2016
Tax credit carryforwards available to offset future federal tax liabilities	$ 5,200
CALIFORNIA
Income Tax [Line Items]
Net operating loss carryforwards	61,900
Net operating loss carryforward,derecognized	$ 3,300

Unrecognized tax benefit (Detail) - USD ($) $ in Thousands	12 Months Ended
Unrecognized tax benefit (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits [Line Items]
Beginning Balance	$ 2,570	$ 2,517
Increase/(Decrease) of unrecognized tax benefits taken in prior years	(1,347)
Increase/(Decrease) of unrecognized tax benefits related to current year	91	53
Ending Balance	$ 1,314	$ 2,570

Collaborations - Additional Information (Detail) $ in Thousands				3 Months Ended								12 Months Ended
	Apr. 02, 2015	Aug. 20, 2013 USD ($) Licenses	Jun. 16, 2013 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Contract revenue				$ 109	$ 109	$ 860	$ 672	$ 672	$ 547	$ 297	$ 297	$ 1,750	$ 1,813	$ 523
Pfizer Inc
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Number of Non-refundable annual license maintenance payments \| Licenses		2
Non-refundable annual license maintenance payments		$ 1,500
Effective termination notice period	60 days
Deferred revenue				0				1,300				0	1,300
Collaboration contract revenue												1,300	1,400	300
Pfizer Inc \| Period 1
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
license maintenance payable period		Aug. 01, 2014
Pfizer Inc \| Period 2
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
license maintenance payable period		Aug. 01, 2013
ISU Abxis
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred revenue				$ 700				$ 1,200				700	1,200
Contract revenue												$ 400	$ 400	$ 100
Deferred revenue recognition period												4 years
ISU Abxis \| Up Front Payment
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Amount received for research and development process			$ 1,750

Basic and Diluted Net Loss Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss	$ (5,129)	$ (5,051)	$ (1,724)	$ (2,858)	$ (1,302)	$ (1,502)	$ (2,075)	$ (1,734)	$ (14,762)	$ (6,613)	$ (9,966)
Weighted-average number of shares used in computing net loss per share, basic and diluted									4,429,093	367,586	365,214
Net loss per share, basic and diluted	$ (0.45)	$ (0.93)	$ (4.60)	$ (7.67)	$ (3.51)	$ (4.08)	$ (5.68)	$ (4.75)	$ (3.33)	$ (17.99)	$ (27.29)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Anti-dilutive Security not Included In Diluted per Share Calculations (Detail) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	6,053,589	3,627,995	3,448,300
Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities		3,338,871	3,188,549
Options To Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	2,200,890	250,255	257,889
Convertible Preferred Stock Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities		37,580
Common Stock Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	180,954	1,289	1,862
Redeemable Convertible Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	3,671,745

Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Data [Line Items]
Contract revenue	$ 109	$ 109	$ 860	$ 672	$ 672	$ 547	$ 297	$ 297	$ 1,750	$ 1,813	$ 523
Total operating expenses	4,794	3,994	3,060	3,704	2,470	2,185	2,507	2,160	15,552	9,322	10,643
Loss from operations	(4,683)	(3,885)	(2,201)	(3,033)	(1,798)	(1,638)	(2,210)	(1,863)	(13,802)	(7,509)	(10,120)
Net loss	$ (5,129)	$ (5,051)	$ (1,724)	$ (2,858)	$ (1,302)	$ (1,502)	$ (2,075)	$ (1,734)	$ (14,762)	$ (6,613)	$ (9,966)
Net loss per share- basic and diluted	$ (0.45)	$ (0.93)	$ (4.60)	$ (7.67)	$ (3.51)	$ (4.08)	$ (5.68)	$ (4.75)	$ (3.33)	$ (17.99)	$ (27.29)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details