Gyre Therapeutics (GYRE) 10-K 19 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Mar. 15, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	CBIO
Entity Registrant Name	CATALYST BIOSCIENCES, INC.
Entity Central Index Key	1,124,105
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	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		11,893,644
Entity Public Float			$ 22,438,884

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 14,472	$ 10,264
Short-term investments	17,971	6,800
Restricted cash	5,333	19,468
Prepaid and other current assets	1,309	958
Accounts receivable	24	31
Total current assets	39,109	37,521
Restricted cash, noncurrent		125
Deposits, noncurrent	128
Property and equipment, net	276	444
Total assets	39,513	38,090
Current liabilities:
Accounts payable	747	837
Accrued compensation	1,366	596
Other accrued liabilities	1,322	805
Deferred revenue, current portion	212	283
Deferred rent, current portion	7	41
Redeemable convertible notes	5,085	19,403
Total current liabilities	8,739	21,965
Deferred revenue, noncurrent portion		47
Deferred rent, noncurrent portion		7
Total liabilities	8,739	22,019
Stockholders’ equity:
Preferred stock, $0.001 par value, 5,000,000 shares authorized; 3,680 and 0 shares issued and outstanding at December 31, 2017 and 2016, respectively
Common stock, $0.001 par value, 100,000,000 shares authorized; 6,081,230 and 801,756 shares issued and outstanding at December 31, 2017 and 2016, respectively	6	1
Additional paid-in capital	204,262	164,053
Accumulated other comprehensive income (loss)		(1)
Accumulated deficit	(173,494)	(147,982)
Total stockholders’ equity	30,774	16,071
Total liabilities and stockholders’ equity	$ 39,513	$ 38,090

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	3,680	0
Preferred stock, shares outstanding	3,680	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	6,081,230	801,756
Common stock, shares outstanding	6,081,230	801,756

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Contract revenue	$ 1,018	$ 399
Operating expenses:
Research and development	12,847	11,555
General and administrative	9,993	9,262
Total operating expenses	22,840	20,817
Loss from operations	(21,822)	(20,418)
Interest and other income, net	261	3,473
Net loss	(21,561)	(16,945)
Deemed dividend for convertible preferred stock beneficial conversion feature	(3,951)
Net loss attributable to common stockholders	$ (25,512)	$ (16,945)
Net loss per share attributable to common stockholders, basic and diluted	$ (7.45)	$ (21.75)
Shares used to compute net loss per share attributable to common stockholders, basic and diluted	3,423,901	779,166

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (21,561)	$ (16,945)
Other comprehensive income (loss):
Unrealized (gain) loss on available-for-sale securities	1	(2)
Total comprehensive loss	$ (21,560)	$ (16,947)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Balance at Dec. 31, 2015	$ 31,425		$ 1	$ 162,460	$ 1	$ (131,037)
Balance (in shares) at Dec. 31, 2015			762,005
Stock-based compensation expense	635			635
Issuance of common stock, net of issuance costs	957			957
Issuance of common stock, net of issuance costs, shares			39,743
Conversion of convertible securities, value	1			1
Conversion of convertible securities, shares			8
Unrealized (loss) gain on available-for-sale securities	(2)				(2)
Net loss	(16,945)					(16,945)
Balance at Dec. 31, 2016	16,071		$ 1	164,053	(1)	(147,982)
Balance (in shares) at Dec. 31, 2016			801,756
Stock-based compensation expense	863			863
Issuance of common stock, net of issuance costs	5,336			5,336
Issuance of common stock, net of issuance costs, shares			439,880
Issuance of convertible preferred stock, common stock and warrants for follow-on offering, net of issuance costs	18,563		$ 2	18,561
Issuance of convertible preferred stock, common stock and warrants for follow-on offering, net of issuance costs, shares		13,350	1,470,000
Issuance of common stock for follow-on offering S-3, net of issuance costs	9,684		$ 1	9,683
Issuance of common stock for follow-on offering S-3, net of issuance costs, shares			1,105,263
Issuance of common stock upon exercise of warrants	1,817			1,817
Issuance of common stock upon exercise of warrants, shares			330,331
Conversion of convertible securities, value			$ 2	(2)
Conversion of convertible securities, shares		(9,670)	1,934,000
Deemed dividend for preferred stock beneficial conversion feature				3,951		(3,951)
Unrealized (loss) gain on available-for-sale securities	1				$ 1
Net loss	(21,561)					(21,561)
Balance at Dec. 31, 2017	$ 30,774		$ 6	$ 204,262		$ (173,494)
Balance (in shares) at Dec. 31, 2017		3,680	6,081,230

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Operating Activities
Net loss	$ (21,561,000)	$ (16,945,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	863,000	635,000
Depreciation and amortization	173,000	389,000
Loss (Gain) on sale of assets	18,000	(2,231,000)
Gain on extinguishment of redeemable convertible notes	0	(99,000)
Change in fair value of derivative liability		(1,057,000)
Changes in operating assets and liabilities:
Prepaid and other current assets	(351,000)	956,000
Accounts receivable	7,000	461,000
Deposits	(128,000)
Accounts payable	(90,000)	(102,000)
Accrued compensation and other accrued liabilities	1,287,000	(60,000)
Deferred revenue	(118,000)	(400,000)
Deferred rent	(40,000)	(19,000)
Net cash flows used in operating activities	(19,940,000)	(18,472,000)
Investing Activities
Proceeds from maturities of short-term investments	14,300,000	10,002,000
Purchase of investments	(25,472,000)	(13,401,000)
Proceeds from sale of assets		1,674,000
Change in restricted cash	(57,000)	(5,000)
Proceeds from sale of property and equipment	0	890,000
Purchases of property and equipment	(23,000)	(468,000)
Net cash flows used in investing activities	(11,252,000)	(1,308,000)
Financing Activities
Release of restricted cash due to conversion and redemption of redeemable convertible notes	14,318,000	14,330,000
Payments for the redemption of redeemable convertible notes	(14,318,000)	(14,340,000)
Proceeds from issuance of common stock, net of issuance costs	5,336,000	958,000
Proceeds from issuance of preferred stock, common stock and warrants for follow-on offering, net of issuance costs	18,563,000
Proceeds from exercise of warrants	1,817,000
Net cash flows provided by financing activities	35,400,000	948,000
Net increase (decrease) in cash and cash equivalents	4,208,000	(18,832,000)
Cash and cash equivalents at beginning of year	10,264,000	29,096,000
Cash and equivalents at end of year	14,472,000	10,264,000
Supplemental Disclosure of Non-Cash Investing and Financing Information:
Deemed dividend for convertible preferred stock beneficial conversion feature	3,951,000
Unrealized (Gain) Loss on investments	1,000	$ (2,000)
S3
Financing Activities
Proceeds from issuance of common stock, net of issuance costs	$ 9,684,000

Nature of Operations

Nature of Operations	12 Months Ended
	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Operations	1. Nature of Operations Catalyst Biosciences, Inc. and its subsidiary (the “Company” or “Catalyst”) is a clinical-stage biotechnology company focused on developing novel medicines to address hematology indications, including the treatment of hemophilia. Its facilities are in South San Francisco, California and it operates in one segment. Prior to August 20, 2015, the name of the Company was Targacept, Inc. (“Targacept”). On August 20, 2015, Targacept completed its business combination with Catalyst (the “Merger”). Liquidity The Company had a net loss of $21.6 million for the year ended December 31, 2017 and an accumulated deficit of $173.5 million as of December 31, 2017 and expects to continue to incur losses for the next several years. As of December 31, 2017, the Company had $32.4 million in cash, cash equivalents and short-term investments and used $20.0 million of cash in operating activities for the year ended December 31, 2017. Management believes that the currently available resources, including cash, cash equivalents and short-term investments, will provide sufficient funds to enable the Company to meet its operating plan for at least the next twelve months from the date of this filing. However, if the Company’s anticipated operating results are not achieved in future periods, management believes that planned expenditures can be reduced to extend the time period over which the then-available resources would be able to fund its operations. The Company plans to continue to fund losses from operations and capital funding needs through future equity and/or debt financings, as well as potential additional asset sales, licensing transactions, collaborations or strategic partnerships with other companies. The sale of additional equity or convertible debt could result in additional dilution to its stockholders. The incurrence of indebtedness would result in debt service obligations and could result in operating and financing covenants that would restrict the Company’s operations. The Company can provide no assurance that financing will be available in the amounts it needs or on terms acceptable to it, if at all. If the Company is not able to secure adequate additional funding it may be forced to delay, make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, and/or suspend or curtail planned programs. Any of these actions could materially harm its business.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
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 United States generally accepted accounting principles (“GAAP”). Use of Estimates The preparation of consolidated financial statements in conformity with 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. Accounting Pronouncements Recently Adopted In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The new standard involves several aspects of the accounting for share-based payment transactions, including the income tax consequences, accounting for forfeitures, classification of awards as either equity or liabilities and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016. We adopted ASU 2016-09 in 2017 and elected to account for forfeitures as they occur and this guidance did not have a material impact on our financial statements. Adoption of the standard did not require any cumulative-effect adjustment to the beginning of the year equity In November 2016, the FASB issued ASU 2016-18, Restricted Cash, which requires amounts generally described as restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the total beginning and ending amounts for the periods shown on the statement of cash flows. ASU 2016-08 is effective for fiscal years beginning after December 15, 2017 using a retrospective transition method to each period presented and early adoption is permitted. We adopted ASU 2016-18 in the first quarter of 2018 and this guidance will have a material impact by decreasing our cash flows from financing activities by $14.3 million. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. The standard provides guidance on how certain cash receipts and payments are presented and classified in the statement of cash flows, including beneficial interests in securitization. The standard is intended to reduce current diversity in practice. We adopted ASU 2016-15 in the first quarter of 2018, and this guidance did not have a material impact on our financial statements. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments – Overall (Topic 825-10), which updates certain aspects of recognition, measurement, presentation and disclosure of financial instruments. ASU 2016-01 will be effective for the Company beginning in the first quarter of 2018, and early adoption is not permitted. We adopted ASU 2016-01 in the first quarter of 2018, and this guidance did not have a material impact on our financial statements. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which amends the existing accounting standards for revenue recognition. ASU 2014-09 is based on principles that govern the recognition of revenue at an amount an entity expects to be entitled when products are transferred to customers. Subsequently, the FASB has issued the following standards related to ASU 2014-09: ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations; ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing; and ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients, (collectively, the “new revenue standards”). We adopted the new revenue standards in the first quarter of 2018, using the modified retrospective method through a cumulative adjustment to equity. While we have identified that the most significant change relates to our accounting for collaboration arrangements with multiple deliverables, in particular, the ISU Abxis agreement. Under the current guidance, such deliverables and consideration must be accounted for under a single unit of accounting along with other arrangement deliverables and consideration that do not have stand-alone value and are recognized as revenue over the estimated period that the performance obligations are to be performed. Under the new standard however, the total arrangement consideration is allocated to each performance obligation based on its estimated stand-alone selling price and revenue is recognized as each performance obligation is satisfied. As a result, we anticipate that revenue for this transaction may be recorded in an earlier period than under the existing guidance, resulting in an immaterial increase to our opening balance of retained earnings as of January 1, 2018. Adopting ASU No. 2014-09, Revenue from Contracts with Customers, or the new revenue standard, will involve significant new estimates and judgments related to the estimates of stand-alone selling prices and the allocation of discounts and variable consideration in allocating the transaction price. We expect that revenue will be recognized earlier under the new standard and may have more variability due to significant estimates involved in the new accounting. Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which replaces the existing guidance for leases. The new standard establishes a right-of-use (ROU) model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. ASU 2016-02 will be effective for the Company beginning in the first quarter of 2019, but early adoption is permitted. We are currently evaluating the impact of adopting the new lease standard on our consolidated financial statements. 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 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 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. 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 The embedded redemption feature in the redeemable convertible notes, which are convertible into shares of the Company’s common stock was bifurcated and 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, as of December 31, 2017 and 2016 the fair value was immaterial. 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 in 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. The Company adopted the new revenue standards in the first quarter of 2018, using the modified retrospective method through a cumulative adjustment to equity. While the Company has identified that the most significant change relates to its accounting for collaboration arrangements with multiple deliverables, in particular, the ISU Abxis agreement. Under the current guidance, such deliverables and consideration must be accounted for under a single unit of accounting along with other arrangement deliverables and consideration that do not have stand-alone value and are recognized as revenue over the estimated period that the performance obligations are to be performed. Under the new standard however, the total arrangement consideration is allocated to each performance obligation based on its estimated stand-alone selling price and revenue is recognized as each performance obligation is satisfied. As a result, the Company anticipates that revenue for this transaction may be recorded in an earlier period than under the existing guidance, resulting in an immaterial increase to its opening balance of retained earnings as of January 1, 2018. 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, 2017 and 2016, the Company recorded a reduction to research and development expenses of $0.1 million and $0.1 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, investments 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. The Company’s accounts receivable at December 31, 2017 was $0.02 million, due from ISU Abxis. 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. Upon adoption of ASU 2016-09, the Company can make an accounting policy election to either estimate the number of share-based awards that are expected to vest, or account for forfeitures when they occur. The Company elected to account for forfeitures when they occur. As such, the Company recognizes stock-based compensation expense, 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

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
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 Liabilities that are measured at fair value consist of the derivative liability associated with the redeemable convertible notes (see Note 9) and are valued using Level 3 inputs. There were no transfers in or out of Level 3 during the periods presented. As of December 31, 2017 and December 31, 2016 the fair value of the derivative liability was immaterial. The estimated reporting date fair value-based measurement of the derivative liability was calculated using the Black-Scholes valuation model. The following tables present the fair value hierarchy for assets and liabilities measured at fair value on a recurring basis as of December 31, 2017 and 2016 ( in thousands December 31, 2017 Level 1 Level 2 Level 3 Total Financial assets: Money market funds (1) $ 14,334 $ — $ — $ 14,334 U.S. government agency securities (3) 16,471 $ — $ — 16,471 Restricted cash (money market funds) (2) 5,333 — — 5,333 Agency securities (3) — 1,500 — 1,500 Total financial assets $ 36,138 $ 1,500 $ — $ 37,638 (1) Included in cash and cash equivalents on accompanying consolidated balance sheets. (2) $5.2 million of restricted cash in the Indenture serves as full collateral for the redeemable convertible notes and $0.1 million of restricted cash serves as collateral for the Company’s corporate credit card and deposit for its facility lease. (3) Included in short-term investments on accompanying consolidated balance sheets and are classified as available-for-sale securities. December 31, 2016 Level 1 Level 2 Level 3 Total Financial assets: Money market funds (1) $ 10,156 $ — $ — $ 10,156 U.S. government agency securities (3) 6,800 — — 6,800 Restricted cash (money market funds) (2) 19,593 — — 19,593 Total financial assets $ 36,549 $ — $ — $ 36,549 (1) Included in cash and cash equivalents on accompanying consolidated balance sheets. (2) $19.4 million of restricted cash in the Indenture serves as full collateral for the redeemable convertible notes and $0.1 million of restricted cash serves as collateral for the Company’s corporate credit card and deposit for its facility lease. (3) Included in short-term investments on accompanying consolidated balance sheets and are classified as available-for-sale securities.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2017
Investments All Other Investments [Abstract]
Financial Instruments	4. Financial Instruments Cash equivalents, restricted cash and short-term investments which are classified as available-for-sale securities, consisted of the following ( in thousands December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Money market funds $ 14,334 $ — $ — $ 14,334 U.S. government agency securities 16,474 — (3 ) 16,471 Restricted cash (money market funds) 5,330 3 — 5,333 Agency securities 1,500 — — 1,500 Total financial assets $ 37,638 $ 3 $ (3 ) $ 37,638 Classified as: Cash and cash equivalents $ 14,334 Short-term investments 17,971 Restricted cash (money market funds) 5,333 $ 37,638 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Money market funds $ 10,156 $ — $ — $ 10,156 U.S. government agency securities 6,802 — (2 ) 6,800 Restricted cash (money market funds) 19,593 — — 19,593 Total financial assets $ 36,551 $ — $ (2 ) $ 36,549 Classified as: Cash and cash equivalents $ 10,156 Restricted cash (money market funds) 19,593 Short-term investments 6,800 $ 36,549 As of December 31, 2017, the remaining contractual maturities of available-for-sale securities was less than one year. There have been no material realized gains or losses on available-for-sale securities for the periods presented. The carrying amounts of cash, accounts receivable, other receivables, accounts payable, other payables and redeemable convertible notes approximate their fair values due to the short-term maturity of these instruments.

Restructuring Actions

Restructuring Actions	12 Months Ended
	Dec. 31, 2017
Restructuring And Related Activities [Abstract]
Restructuring Actions	5. Restructuring Actions In September 2016, the Company announced a reduction in workforce of 10 employees, or approximately 50% of the Company’s workforce, consistent with a revised strategic plan to reallocate our resources to our hemostasis programs, including our highly potent next-generation Factor VIIa variant marzeptacog alfa (activated), and our highly potent next-generation Factor IX CB 2679d/ISU304. The principal objective of the 2016 Restructuring was to enable the Company to focus its efforts and resources on advancing marzeptacog alfa (activated), and CB 2679d/ISU304, through Phase 2/3 and Phase 1/2 clinical trials, respectively. For the year ended December 31, 2016, the Company recorded restructuring charges of $1.0 million, respectively, in R&D expense, due primarily to $0.9 million employee severance and benefits, and $0.1 million for legal and facility expenses in 2016. The restructuring balance was fully paid by December 31, 2016. There were no such charges recorded for the year ended December 31, 2017. In connection with the 2016 restructuring, the Company received proceeds on the sale of equipment of $0.9 million resulting in a gain of $0.6 million which is reported in interest and other income. There were no such proceeds during 2017.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Property and Equipment	6. Property and Equipment Property and equipment consisted of the following ( in thousands Year Ended December 31, 2017 2016 Furniture $ 317 $ 317 Leasehold improvements 1,598 1,613 Computer equipment 237 230 Software 147 144 2,299 2,304 Less accumulated depreciation and amortization (2,023 ) (1,860 ) Property and equipment, net $ 276 $ 444 Property and equipment depreciation and amortization expense for the years ended December 31, 2017 and 2016 was $0.2 million and $0.4 million, respectively. In connection with the Restructuring, the amount recorded as a restructuring charge for asset impairment, as presented in “ Note 5 -Restructuring Actions

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Operating Leases The Company leases office and research space under operating leases that expire in February 2018. As a result of the Restructuring, we exited certain facilities in South San Francisco. In November 2017, we entered into a new office lease agreement to lease approximately 8,606 rentable square feet of space located in South San Francisco, California. The term of the lease is five years and two months, starting February 16, 2018. We relocated our corporate headquarters into this new space in February 2018. The Company’s rental expense under its operating leases was $0.8 million and $0.7 million for the years ended December 31, 2017 and 2016. Future minimum lease payments under all non-cancelable operating leases at December 31, 2017, were as follows ( in thousands 2018 $ 475 2019 489 2020 500 2021 511 2022 523 2023 155 Total future minimum lease payments $ 2,653 Manufacturing Agreements On May 20, 2016, the Company signed a development and manufacturing services agreement with AGC Biologics, Inc. (“AGC”), formerly known as CMC ICOS Biologics, Inc., pursuant to which AGC will conduct manufacturing development and, and together with AGC the Company has successfully manufactured marzeptacog alfa (activated) for the Phase 2 portion of a planned Phase 2/3 clinical trial. The Company has agreed to a total of $3.8 million in payments to AGC pursuant to the initial statement of work under the Agreement, subject to completion of applicable work stages. As of December 31, 2017, the Company’s remaining obligations to AGC were $0.7 million under the agreement. On February 21, 2018, the Company and AGC entered into a new statement of work under the development and manufacturing services agreement dated May 20, 2016, between the Company and AGC. Under the new statement of work, the Company has engaged AGC for the process transfer and commercial scale cGMP manufacturing of CB 2679d, Catalyst’s highly potent next-generation coagulation FIX variant being developed for the treatment of severe hemophilia B. The Company has agreed to a total of approximately $5.6 million in payments pursuant to the new statement of work, including the commercial scale manufacturing of CB 2679d, subject to completion of applicable work stages. 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 12 - Collaborations

Related Parties

Related Parties	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Parties	8. Related Parties On October 24, 2017 the Company announced a strategic research collaboration with Mosaic Biosciences, Inc. (“Mosaic”) to develop intravitreal anti-complement factor 3 (C3) products for the treatment of dry AMD and other retinal diseases. According to the agreement the Company and Mosaic will co fund the research. Dr. Usman, our Chief Executive Officer and a member of our board of directors, and Mr. Lawlor, a member of our board of directors, are also members of the board of directors of Mosaic. Expenses related to the collaboration were $0.03 million for the year ended December 31, 2017.

Redeemable Convertible Notes

Redeemable Convertible Notes	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Redeemable Convertible Notes	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. The Notes do not bear interest. The principal amount of the Notes is convertible, at the option of each noteholder, into cash or into shares of the Company’s common stock at a conversion rate of $137.85 per share, 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 issuance of the Notes, 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 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 Notes into shares of common stock at a conversion price of $137.85 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 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 after the Merger. In addition, changes in the fair value of the derivative liability are being recorded within interest and other income in the consolidated statements of operations. The Company remeasures the derivative liability to fair value until the earlier of the conversion, redemption or maturity of the redeemable convertible notes. As of December 31, 2017 and December 31, 2016, the fair value of the derivative liability was immaterial. The estimated reporting date fair value-based measurement of the derivative liability was calculated using the Black-Scholes valuation model. The Company recognized no interest expense for both years ended December 31, 2017 and 2016, related to the amortization of the debt discount on the Company’s consolidated statement of operations as the redeemable convertible notes are immediately fully redeemable at the option of the holders and the entire debt discount was accreted immediately after the Merger. As of December 31, 2017, the Notes had an outstanding balance of $5.1 million, $31.6 million of the Notes were redeemed and $0.3 million of the Notes were converted into common stock. $14.3 million of the Notes were redeemed during the year ended December 31, 2017. There was $0 and $0.1 million gain on extinguishment when the Notes were redeemed during the years ended December 31, 2017 and 2016, respectively. On February 19, 2018, the Notes matured and the remaining Notes were repaid in full with cash from the restricted cash indenture. The Company has no outstanding Notes remaining as of February 20, 2018.

Stock Based Compensation

Stock Based Compensation	12 Months Ended
	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Based Compensation	10. Stock Based Compensation The following table summarizes stock option activity under the Company’s equity incentive plans 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, 2015 146,634 $ 147.45 5.51 $ 16 Options granted 14,706 $ 23.70 — Fractional shares written off in connection with the merger (1) (4 ) $ — Options canceled (13,773 ) 259.05 Options forfeited (6,573 ) $ 64.95 Outstanding — December 31, 2016 140,990 $ 128.25 3.93 — Options granted 742,000 $ 4.56 Options canceled (141 ) 41.91 Options forfeited (61,108 ) $ 165.63 Outstanding — December 31, 2017 821,741 $ 13.69 9.17 $ 6,376 Exercisable — December 31, 2017 161,240 $ 45.34 Vested and expected to vest — December 31, 2017 821,741 $ 13.69 Shares Available to be granted — December 31, 2017 354,886 (1) In connection with the merger, the Company assumed stock options covering an aggregate of 94,721 shares of common stock. The Company also assumed 190 shares of Restricted Stock Awards which vested in two equal annual installments beginning on December 31, 2015 and fully vesting on December 31, 2016 and excludes 4 aggregate fractional shares written off as a result of the conversion ratio applied to options assumed in the merger. Total stock-based compensation related to these restricted stock awards was $0.02 million for year ended December 31, 2016. Valuation Assumptions The Company estimated the fair value of stock options granted using the Black-Scholes option-pricing formula and a single option award approach. Due to its limited history as a public company and limited number of sales of its common stock, the Company estimated its volatility considering a number of factors including the use of the volatility of comparable public companies. The expected term of options granted under the Plan, all of which qualify as “plain vanilla” per SEC Staff Accounting Bulletin 107, is determined based on the simplified method due to the Company’s limited operating history and is 6.03 years based on the average between the vesting period and the contractual life of the option. The risk-free rate is based on the yield of a U.S. Treasury security with a term consistent with the option. This fair value is being amortized ratably over the requisite service periods of the awards, which is generally the vesting period. The weighted average grant date fair value of employee stock options was $4.01 for the year ended December 31, 2017 and was estimated using the following weighted-average assumptions for the years ended December 31, 2017 and 2016: Year Ended December 31, 2017 2016 Employee Stock Options: Expected term (in years) 6.03 6.14 Risk-free interest rate 2.03 % 1.53 % Dividend yield — — Volatility 110.29 % 76.59 % Options Granted to Nonemployees During the years ended December 31, 2017 and 2016, options to purchase 20,000 and 800 shares, respectively, of common stock were issued to consultants that vest over one to four years with a weighted-average exercise price of $4.69 and $20.40 per share, respectively. During the years ended December 31, 2017, and 2016, the Company recorded stock-based compensation expense attributable to these nonemployee stock awards of $0.02 million and $0.05 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, 2017 2016 Non-Employee Stock Options: Contractual Life (in years) 9 10 Risk-free interest rate 2.35 % 2.39 % Dividend yield — — Volatility 111.55 % 101.12 % Total stock-based compensation recognized was as follows ( in thousands Year Ended December 31, 2017 2016 Research and development $ 699 $ 185 General and administrative 164 450 Total stock-based compensation $ 863 $ 635 As of December 31, 2017, 354,886 shares of common stock were available for future grant and 821,741 options to purchase shares of common stock were outstanding. As of December 31, 2017 the Company had unrecognized employee stock-based compensation expense of $3.2 million, related to unvested stock awards, which is expected to be recognized over an estimated weighted-average period of 2.9 years.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	11. 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, 2017 and 2016 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, 2017 and 2016 are as follows: Year Ended December 31, 2017 2016 Tax at statutory federal rate -34.00 % -34.00 % State Tax (benefit)—net of federal benefit 0.00 % -1.12 % Permanent differences 0.60 % -7.95 % R&D credits -1.64 % -3.16 % Derecognition due to Sec. 382 and 383 limitations 54.08 % 0.00 % Change in valuation allowance -52.90 % 46.66 % Federal tax rate change 33.89 % 0.00 % Other -0.03 % -0.43 % Effective tax rate — — Significant components of the Company’s deferred tax assets as of December 31, 2017 and 2016 consist of the following ( in thousands Year Ended December 31, 2017 2016 Deferred tax assets: Accruals and reserves $ 1,112 $ 1,137 Net operating loss carry forwards 11,519 25,944 R&D tax credit carry forwards 3,545 3,174 Fixed and intangible assets 89 114 Valuation Allowance (16,265 ) (30,369 ) Net deferred tax assets: $ — $ — Based on the available objective evidence at December 31, 2017, the Company does not believe it is more likely than not that the net deferred tax assets (DTA) will be realizable. Accordingly, the Company has provided a full valuation allowance against its net deferred tax assets at December 31, 2017 and 2016. As of December 31, 2017, the Company had federal net operating loss carryforwards of approximately $54.8 million and state net operating loss (NOL) carryforwards of approximately $41.1 million. As of December 31, 2016, the Company had federal net operating loss carryforwards of approximately $68.3 million and state net operating loss carryforwards of approximately $46.6 million. If not utilized, the federal net operating loss carryforwards will begin to expire in 2025 through 2038 and state net operating loss carryforwards will expire from 2028 through 2038. As of December 31, 2017, the Company also had tax credit carry forwards available to offset future tax liabilities of approximately $0.1 million for federal and $4.4 million for state. If unused, the federal credit will begin to expire in 2037 and 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 carryforwards 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 carryforwards before utilization. As of December 31, 2017, the Company determined that ownership changes occurred December 31, 2007, August 20, 2015, and April 13, 2017. As a result of the ownership changes, approximately $108.9 million and $37.7 million of the NOLs will expire unutilized for federal and California purposes, respectively. As of December 31, 2017, the Company has derecognized NOL related DTAs in the tax affected amounts of $22.9 million and $0 million for federal and California purposes, respectively. The ability of the Company to use its remaining NOL carryforwards may be further limited if the Company experiences a Section 382 ownership change as a result of future changes in its stock ownership. 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 $6.1 million of gross federal R&D credit-related deferred tax assets were derecognized due to the Section 383 limitation. 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 $1.5 million of unrecognized tax benefits as of both December 31, 2017 and 2016. 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, 2016 $ 1,314 Increase/(Decrease) of unrecognized tax benefits taken in prior years 6 Increase/(Decrease) of unrecognized tax benefits related to current year 219 Ending Balance at December 31, 2016 $ 1,539 Increase/(Decrease) of unrecognized tax benefits taken in prior years (126 ) Increase/(Decrease) of unrecognized tax benefits related to current year 62 Ending Balance at December 31, 2017 $ 1,475 Interest and penalties related to unrecognized tax benefits would be included as income tax expense in the Company’s consolidated statements of operations. As of December 31, 2017 and 2016, the Company had not recognized any tax-related penalties or interest in its consolidated financial statements. The Company files income tax returns in the United States federal, California, and New Jersey state jurisdictions. The Company is not currently under examination by income tax authorities in federal, state or other jurisdictions. The Company is subject to United States federal and state income tax examinations by authorities for all tax years due to accumulated net operating losses that are being carried forward for tax purposes. On December 22, 2017, the United States government approved a bill reforming the U.S. corporate income tax code which will reduce the corporate tax rate from 34% to 21%. The rate reduction would generally take effect on January 1, 2018. The carrying value of our deferred tax assets is also determined by the enacted U.S. corporate income tax rate. Consequently, any changes in the U.S. corporate income tax rate will impact the carrying value of our deferred tax assets. Under the new corporate income tax rate of 21%, deferred income tax assets will decrease by $7.3 million and valuation allowance will decrease by $7.3 million. The net effect of the tax reform enactment on the Company’s financial statements is $0 as of December 31, 2017.

Collaborations

Collaborations	12 Months Ended
	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaborations	12. Collaborations Pfizer Pursuant to the termination agreement entered on December 8, 2016, in connection with the termination of a prior license and development agreement, Pfizer granted the Company an exclusive license to Pfizer’s proprietary rights for manufacturing materials and processes that apply to Factor VIIa variants, CB 813a and marzeptacog alfa (activated). Pfizer also transferred to the Company the IND application and documentation related to the development, manufacturing and testing of the Factor VIIa products as well as the orphan drug designation. The Company agreed to make contingent cash payments to Pfizer in an aggregate amount equal to up to $17.5 million, payable upon the achievement of clinical, regulatory and commercial milestones. Following commercialization of any covered product, Pfizer would also receive a single-digit royalty on net product sales on a country-by-country basis for a predefined royalty term. No amounts have been paid as of December 31, 2017, under this new agreement. In February 2018, the Company paid Pfizer a $1 million milestone payment based on the dosing of the first patient in the ongoing Phase 2 study. ISU Abxis On September 16, 2013, the Company signed 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 manufacturing, preclinical development activities and clinical development through completion of a proof-of-concept Phase 1/2 study in individuals with hemophilia B. The Company has the sole rights and responsibility for worldwide development, manufacture, and commercialization of Factor IX products after Phase 1/2 development. ISU Abxis may exercise its right of first refusal to acquire commercialization rights in South Korea, in which case they would be entitled to profit sharing on worldwide sales. ISU’s rights will also terminate if the Company enters into a license agreement with another party to develop, manufacture and commercialize Factor IX products in at the United States, European Union or Asia, subject to ISU’s retained rights in South Korea. 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 $0.3 million and $0.4 million for the years ended December 31, 2017 and 2016, respectively, reflects the amortization of the up-front fee over the estimated period of our performance obligations, which concluded in February 2018. In addition, the Company received milestone payments from ISU Abxis of $0.9 million and $0 during the years ended December 31, 2017, and 2016, which are recognized over the estimated remaining period of the Company’s performance obligation under the agreement, of which the Company recorded $0.7 million and $0 for the years ended December 31, 2017 and 2016, respectively. The deferred revenue balance related to the ISU Abxis collaboration was $0.2 million and $0.3 million as of December 31, 2017 and 2016, respectively.

Interest and Other Income

Interest and Other Income	12 Months Ended
	Dec. 31, 2017
Other Income And Expenses [Abstract]
Interest and Other Income	13. Interest and Other Income The following table shows the detail of other income, net for the years ended December 31, 2017 and 2016 (in thousands) Year Ended December 31, 2017 2016 Gain on sale of assets $ — $ 2,231 Change in derivative liability — 1,156 Other Income, net 261 86 Total Other Income, net $ 261 $ 3,473

Stockholders_ Equity

Stockholders’ Equity	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Stockholders' Equity	14. Stockholders’ Equity At the Market Issuance Sales Agreement — On March 16, 2016, the Company signed a Capital on Demand TM The Company sold an aggregate of 479,681 shares of common stock in the open market at a weighted-average selling price of $13.55 per share, for net proceeds (net of commissions) of $6.3 million through December 31, 2017, of which $5.5 million were sold in the year ended December 31, 2017, in the Capital on Demand TM April 2017 Underwritten Public Offering — On April 12, 2017, the Company issued and sold in a registered, underwritten public offering an aggregate of (i) 1,470,000 shares of common stock (including 540,000 shares of common stock sold pursuant to the exercise of the Underwriter’s overallotment option), (ii) 13,350 shares of Series A Preferred Stock, each convertible into 200 shares of common stock and (iii) warrants to purchase 2,070,000 shares of common stock at an exercise price of $5.50 per share (including 270,000 sold pursuant to the exercise of the Underwriter’s overallotment option). The net proceeds to the Company, after deducting the underwriting discounts and commissions and offering expenses payable by the Company were approximately $18.6 million. Series A Convertible Preferred Stock — In connection with the closing on April 12, 2017 of the public offering, the Company filed the Certificate of Designation of Preferences, Rights and Limitations of the Series A Preferred Stock (the “Certificate of Designation”) with the Secretary of State of the State of Delaware. The Certificate of Designation describes the rights, preferences and privileges of the shares of Series A Preferred Stock. With certain exceptions, the shares of Series A Preferred Stock rank on par with the shares of the Common Stock, in each case, as to dividend rights and distributions of assets upon liquidation, dissolution or winding up of the Company. Upon its issuance, the Series A Preferred Stock was not considered a liability or temporary equity and as such the Series A Preferred Stock was recorded in permanent equity on the Company’s balance sheet. During the year ended December 31, 2017, 9,670 shares of the Company’s Series A Preferred Stock were converted into 1,934,000 shares of common stock of the Company. As of December 31, 2017, there were 3,680 shares of Series A Preferred Stock issued and outstanding. Beneficial Conversion Feature Series A Preferred Stock (deemed dividend) — Each share of Series A Preferred Stock is convertible into 200 shares of common stock, at any time, at the option of the holder. The net proceeds to the Company of $18.6 million were allocated to the common stock, Preferred A Stock and warrants (see below) based on a relative fair value basis. This resulted in $10.1 million being allocated to the Preferred A Stock and resulted in an effective conversion price of $3.80 per share. On April 12, 2017, the date of issuance of the Series A Preferred Stock, the publicly traded common stock price was $5.28 per share. Based on the guidance in ASC 470-20-20, the Company determined that a beneficial conversion feature exists, as the effective conversion price for the shares of Series A Preferred Stock at issuance was less than the fair value of the common stock into which the shares of Series A Preferred Stock are convertible. The beneficial conversion feature calculated based on the intrinsic value as of the date of issuance was approximately $4.0 million. This amount was then accreted as a deemed dividend, which is a non-cash transaction. As the conversion rights were 100% effective at the time of issuance, the deemed dividend was immediately charged to accumulated deficit. Warrants — In connection with the closing on April 12, 2017 of the public offering and the overallotment option, the Company issued warrants to purchase 2,070,000 shares of common stock at an exercise price of $5.50 per share. Upon their issuance, the common stock warrants were determined to be equity instruments under ASC 480 and ASC 815-40. The net proceeds allocated to the warrants based on a relative fair value basis resulted in $5.0 million being allocated to the warrants. The following is a summary of warrant activity for the year ended December 31, 2016 and 2017: Number of Shares Underlying Warrants Exercise Price Outstanding — December 31, 2016 12,039 $ 145.11 Issued 2,070,000 $ 5.50 Exercised (330,331 ) $ 5.50 Outstanding — December 31, 2017 1,751,708 December 2017 Underwritten Public Offering — On December 20, 2017, the Company entered into an underwriting agreement with JonesTrading, in connection with a registered firm commitment underwritten public offering of 1,105,263 shares of the Company’s common stock, pursuant to a shelf registration statement that was declared effective by the SEC on April 28, 2016. On December 22, 2017 the Company sold an aggregate of 1,105,263 shares of common stock at a price to the public of at $9.50 per share. The net proceeds to the Company, after deducting the underwriting discounts and commissions and offering expenses payable by the Company were approximately $9.7 million. February 2018 Underwritten Public Offering — On February 13, 2018, the Company entered into an underwriting agreement with JonesTrading, in connection with a registered firm commitment underwritten public offering of 2,941,176 shares of common stock, pursuant to a shelf registration statement that was declared effective by the SEC on February 6, 2018. On February 15, 2018 the Company sold 3,382,352 shares of common stock (including 441,176 shares of common stock sold pursuant to the exercise of the underwriters’ overallotment option) at a price to the public of $34.00 per share. The net proceeds to the Company, after deducting the underwriting discounts and commissions and offering expenses payable by the Company were approximately $106.7 million.

Net Loss per Share Attributable

Net Loss per Share Attributable to Common Stockholders	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Net Loss per Share Attributable to Common Stockholders	15. Net Loss per Share Attributable to Common Stockholders The following table sets forth the computation of the basic and diluted net loss per common share during the years ended December 31, 2017 and 2016 (in thousands, except share and per share data) Year Ended December 31, 2017 2016 Net loss attributable to common stockholders $ (25,512 ) $ (16,945 ) Weighted-average number of shares used in computing net loss per share, basic and diluted 3,423,901 779,166 Net loss per share, basic and diluted $ (7.45 ) $ (21.75 ) 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, 2017 2016 Options to purchase common stock 821,741 140,990 Convertible preferred stock (1) 736,000 — Common stock warrants 1,751,708 12,063 Redeemable convertible notes 36,883 140,743 Total 3,346,332 293,796 (1) As of December 31, 2017, represents 3,680 shares of Series A Preferred Stock on an as converted basis to 0.7 million shares of common stock.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	16. Subsequent Events On February 13, 2018, the Company entered into an underwriting agreement with JonesTrading, in connection with a registered firm commitment underwritten public offering of 2,941,176 shares of common stock, pursuant to a shelf registration statement that was declared effective by the SEC on February 6, 2018. On February 15, 2018 the Company sold 3,382,352 shares of common stock (including 441,176 shares of common stock sold pursuant to the exercise of the underwriters’ overallotment option) at a price to the public of $34.00 per share. The net proceeds to the Company, after deducting the underwriting discounts and commissions and offering expenses payable by the Company were approximately $106.7 million. On February 19, 2018, the Redeemable Convertible notes matured and the remaining Notes were repaid in full with cash from the restricted cash indenture. The Company has no outstanding Notes remaining as of February 20, 2018. On February 21, 2018, the Company and AGC Biologics (“AGC”), formerly known as CMC ICOS Biologics, Inc. entered into a new statement of work under the development and manufacturing services agreement dated May 20, 2016, between the Company and AGC. Under the new statement of work, the Company has engaged AGC for the process transfer and commercial scale cGMP manufacturing of CB 2679d, Catalyst’s highly potent next-generation coagulation FIX variant being developed for the treatment of severe hemophilia B. The Company has agreed to a total of approximately $5.6 million in payments pursuant to the new statement of work, including the commercial scale manufacturing of CB 2679d, subject to completion of applicable work stages. On March 2, 2018, the Company called all 3,580 outstanding shares of Series A Preferred Stock to be converted into common stock effective as of March 7, 2018. As of March 15, 2018, the Series A Preferred Stock was converted into 716,000 shares of common stock and there were no Series A Preferred Stock outstanding. On March 5, 2018, the Company called the remaining 254,628 outstanding warrants. As of March 15, 2018, there were 45,628 warrants remaining and approximately $9.3 million proceeds received from warrants exercised during 2018. Warrant holders have until 6:30PM EST on March 19, 2018 to exercise their warrants, after this date the remaining outstanding warrants will be cancelled and the right to exercise such warrants will extinguish.

Summary of Significant Accoun24

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
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 United States generally accepted accounting principles (“GAAP”).
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with 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.
Accounting Pronouncements Recently Adopted	Accounting Pronouncements Recently Adopted In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The new standard involves several aspects of the accounting for share-based payment transactions, including the income tax consequences, accounting for forfeitures, classification of awards as either equity or liabilities and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016. We adopted ASU 2016-09 in 2017 and elected to account for forfeitures as they occur and this guidance did not have a material impact on our financial statements. Adoption of the standard did not require any cumulative-effect adjustment to the beginning of the year equity In November 2016, the FASB issued ASU 2016-18, Restricted Cash, which requires amounts generally described as restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the total beginning and ending amounts for the periods shown on the statement of cash flows. ASU 2016-08 is effective for fiscal years beginning after December 15, 2017 using a retrospective transition method to each period presented and early adoption is permitted. We adopted ASU 2016-18 in the first quarter of 2018 and this guidance will have a material impact by decreasing our cash flows from financing activities by $14.3 million. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. The standard provides guidance on how certain cash receipts and payments are presented and classified in the statement of cash flows, including beneficial interests in securitization. The standard is intended to reduce current diversity in practice. We adopted ASU 2016-15 in the first quarter of 2018, and this guidance did not have a material impact on our financial statements. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments – Overall (Topic 825-10), which updates certain aspects of recognition, measurement, presentation and disclosure of financial instruments. ASU 2016-01 will be effective for the Company beginning in the first quarter of 2018, and early adoption is not permitted. We adopted ASU 2016-01 in the first quarter of 2018, and this guidance did not have a material impact on our financial statements. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which amends the existing accounting standards for revenue recognition. ASU 2014-09 is based on principles that govern the recognition of revenue at an amount an entity expects to be entitled when products are transferred to customers. Subsequently, the FASB has issued the following standards related to ASU 2014-09: ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations; ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing; and ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients, (collectively, the “new revenue standards”). We adopted the new revenue standards in the first quarter of 2018, using the modified retrospective method through a cumulative adjustment to equity. While we have identified that the most significant change relates to our accounting for collaboration arrangements with multiple deliverables, in particular, the ISU Abxis agreement. Under the current guidance, such deliverables and consideration must be accounted for under a single unit of accounting along with other arrangement deliverables and consideration that do not have stand-alone value and are recognized as revenue over the estimated period that the performance obligations are to be performed. Under the new standard however, the total arrangement consideration is allocated to each performance obligation based on its estimated stand-alone selling price and revenue is recognized as each performance obligation is satisfied. As a result, we anticipate that revenue for this transaction may be recorded in an earlier period than under the existing guidance, resulting in an immaterial increase to our opening balance of retained earnings as of January 1, 2018. Adopting ASU No. 2014-09, Revenue from Contracts with Customers, or the new revenue standard, will involve significant new estimates and judgments related to the estimates of stand-alone selling prices and the allocation of discounts and variable consideration in allocating the transaction price. We expect that revenue will be recognized earlier under the new standard and may have more variability due to significant estimates involved in the new accounting.
Accounting Pronouncements Not Yet Adopted	Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which replaces the existing guidance for leases. The new standard establishes a right-of-use (ROU) model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. ASU 2016-02 will be effective for the Company beginning in the first quarter of 2019, but early adoption is permitted. We are currently evaluating the impact of adopting the new lease standard on our consolidated financial statements.
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 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
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.
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 was bifurcated and 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, as of December 31, 2017 and 2016 the fair value was immaterial.
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 in 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. The Company adopted the new revenue standards in the first quarter of 2018, using the modified retrospective method through a cumulative adjustment to equity. While the Company has identified that the most significant change relates to its accounting for collaboration arrangements with multiple deliverables, in particular, the ISU Abxis agreement. Under the current guidance, such deliverables and consideration must be accounted for under a single unit of accounting along with other arrangement deliverables and consideration that do not have stand-alone value and are recognized as revenue over the estimated period that the performance obligations are to be performed. Under the new standard however, the total arrangement consideration is allocated to each performance obligation based on its estimated stand-alone selling price and revenue is recognized as each performance obligation is satisfied. As a result, the Company anticipates that revenue for this transaction may be recorded in an earlier period than under the existing guidance, resulting in an immaterial increase to its opening balance of retained earnings as of January 1, 2018.
Research and Development Expenses	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, 2017 and 2016, the Company recorded a reduction to research and development expenses of $0.1 million and $0.1 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, investments 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. The Company’s accounts receivable at December 31, 2017 was $0.02 million, due from ISU Abxis. 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. Upon adoption of ASU 2016-09, the Company can make an accounting policy election to either estimate the number of share-based awards that are expected to vest, or account for forfeitures when they occur. The Company elected to account for forfeitures when they occur. As such, the Company recognizes stock-based compensation expense, 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

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
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, 2017 and 2016 ( in thousands December 31, 2017 Level 1 Level 2 Level 3 Total Financial assets: Money market funds (1) $ 14,334 $ — $ — $ 14,334 U.S. government agency securities (3) 16,471 $ — $ — 16,471 Restricted cash (money market funds) (2) 5,333 — — 5,333 Agency securities (3) — 1,500 — 1,500 Total financial assets $ 36,138 $ 1,500 $ — $ 37,638 (1) Included in cash and cash equivalents on accompanying consolidated balance sheets. (2) $5.2 million of restricted cash in the Indenture serves as full collateral for the redeemable convertible notes and $0.1 million of restricted cash serves as collateral for the Company’s corporate credit card and deposit for its facility lease. (3) Included in short-term investments on accompanying consolidated balance sheets and are classified as available-for-sale securities. December 31, 2016 Level 1 Level 2 Level 3 Total Financial assets: Money market funds (1) $ 10,156 $ — $ — $ 10,156 U.S. government agency securities (3) 6,800 — — 6,800 Restricted cash (money market funds) (2) 19,593 — — 19,593 Total financial assets $ 36,549 $ — $ — $ 36,549 (1) Included in cash and cash equivalents on accompanying consolidated balance sheets. (2) $19.4 million of restricted cash in the Indenture serves as full collateral for the redeemable convertible notes and $0.1 million of restricted cash serves as collateral for the Company’s corporate credit card and deposit for its facility lease. (3) Included in short-term investments on accompanying consolidated balance sheets and are classified as available-for-sale securities.

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Investments All Other Investments [Abstract]
Cash Equivalents, Restricted Cash and Short-Term Investments Classified as Available-for-sale Securities	Cash equivalents, restricted cash and short-term investments which are classified as available-for-sale securities, consisted of the following ( in thousands December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Money market funds $ 14,334 $ — $ — $ 14,334 U.S. government agency securities 16,474 — (3 ) 16,471 Restricted cash (money market funds) 5,330 3 — 5,333 Agency securities 1,500 — — 1,500 Total financial assets $ 37,638 $ 3 $ (3 ) $ 37,638 Classified as: Cash and cash equivalents $ 14,334 Short-term investments 17,971 Restricted cash (money market funds) 5,333 $ 37,638 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Money market funds $ 10,156 $ — $ — $ 10,156 U.S. government agency securities 6,802 — (2 ) 6,800 Restricted cash (money market funds) 19,593 — — 19,593 Total financial assets $ 36,551 $ — $ (2 ) $ 36,549 Classified as: Cash and cash equivalents $ 10,156 Restricted cash (money market funds) 19,593 Short-term investments 6,800 $ 36,549

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Schedule of Property and equipment	Property and equipment consisted of the following ( in thousands Year Ended December 31, 2017 2016 Furniture $ 317 $ 317 Leasehold improvements 1,598 1,613 Computer equipment 237 230 Software 147 144 2,299 2,304 Less accumulated depreciation and amortization (2,023 ) (1,860 ) Property and equipment, net $ 276 $ 444

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments under All Non-cancelable Operating Leases	Future minimum lease payments under all non-cancelable operating leases at December 31, 2017, were as follows ( in thousands 2018 $ 475 2019 489 2020 500 2021 511 2022 523 2023 155 Total future minimum lease payments $ 2,653

Stock Based Compensation (Table

Stock Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Summary of Option Activity Under Company's Equity Incentive Plans	The following table summarizes stock option activity under the Company’s equity incentive plans 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, 2015 146,634 $ 147.45 5.51 $ 16 Options granted 14,706 $ 23.70 — Fractional shares written off in connection with the merger (1) (4 ) $ — Options canceled (13,773 ) 259.05 Options forfeited (6,573 ) $ 64.95 Outstanding — December 31, 2016 140,990 $ 128.25 3.93 — Options granted 742,000 $ 4.56 Options canceled (141 ) 41.91 Options forfeited (61,108 ) $ 165.63 Outstanding — December 31, 2017 821,741 $ 13.69 9.17 $ 6,376 Exercisable — December 31, 2017 161,240 $ 45.34 Vested and expected to vest — December 31, 2017 821,741 $ 13.69 Shares Available to be granted — December 31, 2017 354,886 (1) In connection with the merger, the Company assumed stock options covering an aggregate of 94,721 shares of common stock. The Company also assumed 190 shares of Restricted Stock Awards which vested in two equal annual installments beginning on December 31, 2015 and fully vesting on December 31, 2016 and excludes 4 aggregate fractional shares written off as a result of the conversion ratio applied to options assumed in the merger. Total stock-based compensation related to these restricted stock awards was $0.02 million for year ended December 31, 2016.
Summary of Stock-Based Compensation Recognized	Total stock-based compensation recognized was as follows ( in thousands Year Ended December 31, 2017 2016 Research and development $ 699 $ 185 General and administrative 164 450 Total stock-based compensation $ 863 $ 635
Employee Stock Option
Summary of Weighted Average Valuation Assumptions Used to Estimate Fair Value	Year Ended December 31, 2017 2016 Employee Stock Options: Expected term (in years) 6.03 6.14 Risk-free interest rate 2.03 % 1.53 % Dividend yield — — Volatility 110.29 % 76.59 %
Non Employee Stock Option
Summary of Weighted Average Valuation Assumptions Used to Estimate Fair Value	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, 2017 2016 Non-Employee Stock Options: Contractual Life (in years) 9 10 Risk-free interest rate 2.35 % 2.39 % Dividend yield — — Volatility 111.55 % 101.12 %

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
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, 2017 and 2016 are as follows: Year Ended December 31, 2017 2016 Tax at statutory federal rate -34.00 % -34.00 % State Tax (benefit)—net of federal benefit 0.00 % -1.12 % Permanent differences 0.60 % -7.95 % R&D credits -1.64 % -3.16 % Derecognition due to Sec. 382 and 383 limitations 54.08 % 0.00 % Change in valuation allowance -52.90 % 46.66 % Federal tax rate change 33.89 % 0.00 % Other -0.03 % -0.43 % Effective tax rate — —
Components of the Company's Deferred Tax Assets (Liabilities)	Significant components of the Company’s deferred tax assets as of December 31, 2017 and 2016 consist of the following ( in thousands Year Ended December 31, 2017 2016 Deferred tax assets: Accruals and reserves $ 1,112 $ 1,137 Net operating loss carry forwards 11,519 25,944 R&D tax credit carry forwards 3,545 3,174 Fixed and intangible assets 89 114 Valuation Allowance (16,265 ) (30,369 ) 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, 2016 $ 1,314 Increase/(Decrease) of unrecognized tax benefits taken in prior years 6 Increase/(Decrease) of unrecognized tax benefits related to current year 219 Ending Balance at December 31, 2016 $ 1,539 Increase/(Decrease) of unrecognized tax benefits taken in prior years (126 ) Increase/(Decrease) of unrecognized tax benefits related to current year 62 Ending Balance at December 31, 2017 $ 1,475

Interest and Other Income (Tabl

Interest and Other Income (Tables)	12 Months Ended
	Dec. 31, 2017
Other Income And Expenses [Abstract]
Detail of Other Income, Net	The following table shows the detail of other income, net for the years ended December 31, 2017 and 2016 (in thousands) Year Ended December 31, 2017 2016 Gain on sale of assets $ — $ 2,231 Change in derivative liability — 1,156 Other Income, net 261 86 Total Other Income, net $ 261 $ 3,473

Stockholders_ Equity (Tables)

Stockholders’ Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Summary of Warrant Activity	The following is a summary of warrant activity for the year ended December 31, 2016 and 2017: Number of Shares Underlying Warrants Exercise Price Outstanding — December 31, 2016 12,039 $ 145.11 Issued 2,070,000 $ 5.50 Exercised (330,331 ) $ 5.50 Outstanding — December 31, 2017 1,751,708

Net Loss per Share Attributab33

Net Loss per Share Attributable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Basic and Diluted 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, 2017 and 2016 (in thousands, except share and per share data) Year Ended December 31, 2017 2016 Net loss attributable to common stockholders $ (25,512 ) $ (16,945 ) Weighted-average number of shares used in computing net loss per share, basic and diluted 3,423,901 779,166 Net loss per share, basic and diluted $ (7.45 ) $ (21.75 )
Anti-dilutive Security not Included In Diluted per Share Calculations	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, 2017 2016 Options to purchase common stock 821,741 140,990 Convertible preferred stock (1) 736,000 — Common stock warrants 1,751,708 12,063 Redeemable convertible notes 36,883 140,743 Total 3,346,332 293,796 (1) As of December 31, 2017, represents 3,680 shares of Series A Preferred Stock on an as converted basis to 0.7 million shares of common stock.

Nature of Operations - Addition

Nature of Operations - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Segment	Dec. 31, 2016USD ($)
Accounting Policies [Abstract]
Number of operating segment | Segment	1
Accumulated deficit	$ 173,494	$ 147,982
Cash, cash equivalents and short-term investments	32,400
Net loss	21,561	16,945
Cash used in operations	$ 19,940	$ 18,472

Summary of Significant Accoun35

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Significant Accounting Policies [Line Items]
Decrease in cash flows from financing activities by adoption of accounting pronouncements		$ (35,400)	$ (948)
Reduction to research and development expenses		100	100
Accounts receivable		24	$ 31
ISU Abxis
Significant Accounting Policies [Line Items]
Accounts receivable		$ 20
Software
Significant Accounting Policies [Line Items]
Estimated useful lives		3 years
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
Scenario Forecast | ASU 2016-18
Significant Accounting Policies [Line Items]
Decrease in cash flows from financing activities by adoption of accounting pronouncements	$ 14,300

Assets and Liabilities Measured

Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands		Dec. 31, 2017		Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value		$ 37,638		$ 36,549
Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	[1]	14,334		10,156
Restricted cash (money market funds)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value		5,333	[2]	19,593	[3]
U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	[4]	16,471		6,800
Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	[4]	1,500
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value		36,138		36,549
Fair Value, Inputs, Level 1 | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	[1]	14,334		10,156
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		5,333	[2]	19,593	[3]
Fair Value, Inputs, Level 1 | U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	[4]	16,471		$ 6,800
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value		1,500
Fair Value, Inputs, Level 2 | Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	[4]	$ 1,500
[1]	Included in cash and cash equivalents on accompanying consolidated balance sheets.
[2]	$5.2 million of restricted cash in the Indenture serves as full collateral for the redeemable convertible notes and $0.1 million of restricted cash serves as collateral for the Company’s corporate credit card and deposit for its facility lease.
[3]	$19.4 million of restricted cash in the Indenture serves as full collateral for the redeemable convertible notes and $0.1 million of restricted cash serves as collateral for the Company’s corporate credit card and deposit for its facility lease.
[4]	Included in short-term investments on accompanying consolidated balance sheets and are classified as available-for-sale securities.

Assets and Liabilities Measur37

Assets and Liabilities Measured at Fair Value (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Collateral for Redeemable Convertible Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash	$ 5.2	$ 19.4
Collateral for Corporate Credit Card and Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash	$ 0.1	$ 0.1

Cash Equivalents, Restricted Ca

Cash Equivalents, Restricted Cash and Short-Term Investments Classified as Available-for-sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 37,638	$ 36,551
Gross Unrealized Gains	3
Gross Unrealized Losses	(3)	(2)
Estimated Fair Value	37,638	36,549
Money Market Funds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,334	10,156
Estimated Fair Value	14,334	10,156
Money Market Funds | Restricted cash (money market funds)
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,330	19,593
Gross Unrealized Gains	3
Estimated Fair Value	5,333	19,593
U.S. Government Agency Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	16,474	6,802
Gross Unrealized Losses	(3)	(2)
Estimated Fair Value	16,471	6,800
Cash and Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	14,334	10,156
Short-Term Investments
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	17,971	$ 6,800
Agency Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,500
Estimated Fair Value	$ 1,500

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)
Financial Instrument [Line Items]
Material 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)

Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 2,299	$ 2,304
Less accumulated depreciation and amortization	(2,023)	(1,860)
Property and equipment, net	276	444
Software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	147	144
Furniture
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	317	317
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	1,598	1,613
Computer equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 237	$ 230

Property and Equipment - Additi

Property and Equipment - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Depreciation expense	$ 0.2	$ 0.4

Restructuring Actions - Additio

Restructuring Actions - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Sep. 30, 2016Employee	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Restructuring Cost And Reserve [Line Items]
Restructuring charges		$ 0
Proceeds from sale of equipment		$ 0	$ 890,000
R&D Expense
Restructuring Cost And Reserve [Line Items]
Restructuring charges			1,000,000
Interest and Other Income
Restructuring Cost And Reserve [Line Items]
Gain on sale of equipment			600,000
Employee Severance and Benefits
Restructuring Cost And Reserve [Line Items]
Reduction in workforce | Employee	10
Percentage of workforce reduced	50.00%
Restructuring charges			900,000
Legal and Facility Expenses
Restructuring Cost And Reserve [Line Items]
Restructuring charges			$ 100,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended		12 Months Ended
	Feb. 28, 2018USD ($)	Nov. 30, 2017ft²	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2013USD ($)	Feb. 21, 2018USD ($)	May 20, 2016USD ($)
Commitments And Contingencies Disclosure [Line Items]
Operating lease expiration date			2018-02
Operating lease rent expense			$ 800,000	$ 700,000
License fees payable					$ 100,000
AGC Biologics, Inc
Commitments And Contingencies Disclosure [Line Items]
Contractual obligation payments			700,000				$ 3,800,000
AGC Biologics, Inc | Subsequent Event
Commitments And Contingencies Disclosure [Line Items]
Contractual obligation payments						$ 5,600,000
ISU Abxis | Maximum
Commitments And Contingencies Disclosure [Line Items]
Potential milestone payments			2,000,000
Pfizer Inc | Collaboration Agreement | Maximum
Commitments And Contingencies Disclosure [Line Items]
Obligated to make milestone and royalty payments upon achievement of clinical, regulatory and commercial milestones			$ 17,500,000
Pfizer Inc | Subsequent Event | Collaboration Agreement
Commitments And Contingencies Disclosure [Line Items]
Milestone payment	$ 1,000,000
South San Francisco, California | New Office Lease Agreement
Commitments And Contingencies Disclosure [Line Items]
Leased area | ft²		8,606
Operating lease term of contract		5 years 2 months
Operating lease commencement date		Feb. 16, 2018

Schedule of Future Minimum Leas

Schedule of Future Minimum Lease Payments under All Non-cancelable Operating Leases (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,018	$ 475
2,019	489
2,020	500
2,021	511
2,022	523
2,023	155
Total future minimum lease payments	$ 2,653

Related Parties - Additional In

Related Parties - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Mosaic | Strategic Research Collaboration to Develop Intravitreal Anti-Complement Factor 3 (C3) Products
Related Party Transaction [Line Items]
Expenses related to collaboration	$ 30

Redeemable Convertible Notes -

Redeemable Convertible Notes - Additional Information (Detail)	Feb. 19, 2018USD ($)	Dec. 31, 2017USD ($)d$ / shares	Dec. 31, 2016USD ($)	Feb. 20, 2018USD ($)	Aug. 19, 2015USD ($)
Debt Instrument [Line Items]
Redeemable convertible notes, outstanding balance		$ 5,085,000	$ 19,403,000
Conversion of convertible notes in to common stock, value			1,000
Gain on extinguishment of redeemable convertible notes		0	99,000
Redeemable convertible notes, redeemed during period		$ 14,318,000	14,340,000
Subsequent Event
Debt Instrument [Line Items]
Redeemable convertible notes, outstanding balance				$ 0
Convertible Notes
Debt Instrument [Line Items]
Convertible notes, total outstanding principal amount					$ 37,000,000
Redeemable convertible notes, conversion per share price | $ / shares		$ 137.85
Convertible notes, maturity date		Feb. 19, 2018
Convertible notes, maturity period		30 months
Redeemable convertible notes, threshold trading days | d		10
Redeemable convertible notes, conversion feature		$ 1,500,000
Redeemable convertible notes, estimated fair value		37,100,000
Redeemable convertible notes, debt discount		1,400,000
Redeemable convertible notes, interest expense		0	$ 0
Redeemable convertible notes, redeemed		31,600,000
Conversion of convertible notes in to common stock, value		300,000
Redeemable convertible notes, redeemed during period		$ 14,300,000
Convertible Notes | Subsequent Event
Debt Instrument [Line Items]
Convertible notes, maturity date	Feb. 19, 2018
Redeemable convertible notes, outstanding balance	$ 0
Convertible Notes | After Reverse Stock Split
Debt Instrument [Line Items]
Redeemable convertible notes, conversion per share price | $ / shares		$ 137.85

Summary of Option Activity Unde

Summary of Option Activity Under Company's Equity Incentive Plans (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Shares Underlying Outstanding Options
Number of Shares Underlying Outstanding Options, Beginning Balance		140,990	146,634
Number of Shares Underlying Outstanding Options, Options granted		742,000	14,706
Number of Shares Underlying Outstanding Options, Fractional shares written off in connection with the merger	[1]		(4)
Number of Shares Underlying Outstanding Options, Options canceled		(141)	(13,773)
Number of Shares Underlying Outstanding Options, Options forfeited		(61,108)	(6,573)
Number of Shares Underlying Outstanding Options, Ending Balance		821,741	140,990	146,634
Number of Shares Underlying Outstanding Options, Exercisable- December 31, 2017		161,240
Number of Shares Underlying Outstanding Options, Vested and expected to vest - December 31, 2017		821,741
Shares Available to be granted - December 31, 2017		354,886
Weighted- Average Exercise Price
Weighted- Average Exercise Price, Beginning Balance		$ 128.25	$ 147.45
Weighted- Average Exercise Price, Options granted		4.56	23.70
Weighted- Average Exercise Price, Options canceled		41.91	259.05
Weighted- Average Exercise Price, Options forfeited		165.63	64.95
Weighted- Average Exercise Price, Ending Balance		13.69	$ 128.25	$ 147.45
Weighted- Average Exercise Price, Exercisable - December 31, 2017		45.34
Weighted- Average Exercise Price, Vested and expected to vest - December 31, 2017		$ 13.69
Weighted-Average Remaining Contractual Term (Years)
Weighted-Average Remaining Contractual Term (Years), Outstanding Balance		9 years 2 months 1 day	3 years 11 months 4 days	5 years 6 months 3 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding		$ 6,376		$ 16
[1]	In connection with the merger, the Company assumed stock options covering an aggregate of 94,721 shares of common stock. The Company also assumed 190 shares of Restricted Stock Awards which vested in two equal annual installments beginning on December 31, 2015 and fully vesting on December 31, 2016 and excludes 4 aggregate fractional shares written off as a result of the conversion ratio applied to options assumed in the merger. Total stock-based compensation related to these restricted stock awards was $0.02 million for year ended December 31, 2016.

Summary of Option Activity Un48

Summary of Option Activity Under Company's Equity Incentive Plans (Parenthetical) (Detail) $ in Thousands		12 Months Ended
		Dec. 31, 2016USD ($)shares	Dec. 31, 2015Installmentshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate fractional shares written off in merger	[1]	4
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock awards, assumed in merger			190
Number of Shares Underlying Outstanding Options, Options assumed in merger			94,721
Number of equal annual installments | Installment			2
Aggregate fractional shares written off in merger		4
Total stock based compensation | $		$ 20
[1]	In connection with the merger, the Company assumed stock options covering an aggregate of 94,721 shares of common stock. The Company also assumed 190 shares of Restricted Stock Awards which vested in two equal annual installments beginning on December 31, 2015 and fully vesting on December 31, 2016 and excludes 4 aggregate fractional shares written off as a result of the conversion ratio applied to options assumed in the merger. Total stock-based compensation related to these restricted stock awards was $0.02 million for year ended December 31, 2016.

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Outstanding, Weighted Average Exercise Price	$ 13.69	$ 128.25	$ 147.45
Stock-based compensation expense	$ 863	$ 635
Number of common stock available for future grant	354,886
Shares remaining outstanding	821,741
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term of stock options	6 years 10 days	6 years 1 month 20 days
Weighted average grant date fair value of stock options	$ 4.01
Unrecognized employee stock based compensation expense	$ 3,200
Unrecognized employee stock based compensation expense, period for recognition	2 years 10 months 24 days
Non Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term of stock options	9 years 5 months 23 days	9 years 8 months 26 days
Options, Grants in Period	20,000	800
Options, Outstanding, Weighted Average Exercise Price	$ 4.69	$ 20.40
Stock-based compensation expense	$ 20	$ 50
Non Employee Stock Option | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Period	1 year	1 year
Non Employee Stock Option | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Period	4 years	4 years

Fair Values of Stock Options Es

Fair Values of Stock Options Estimated Using Black-Scholes Valuation Model (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Black Scholes Method Used [Line Items]
Expected term / Contractual Life (in years)	6 years 10 days	6 years 1 month 20 days
Risk-free interest rate	2.03%	1.53%
Dividend yield	0.00%	0.00%
Volatility	110.29%	76.59%
Non Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Black Scholes Method Used [Line Items]
Expected term / Contractual Life (in years)	9 years 5 months 23 days	9 years 8 months 26 days
Risk-free interest rate	2.35%	2.39%
Dividend yield	0.00%	0.00%
Volatility	111.55%	101.12%

Summary of Stock-Based Compensa

Summary of Stock-Based Compensation Recognized (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 863	$ 635
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	699	185
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 164	$ 450

Reconciliation of Statutory Fed

Reconciliation of Statutory Federal Income Tax (benefit) Rate to Company's Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Tax at statutory federal rate	(34.00%)	(34.00%)
State Tax (benefit)—net of federal benefit	(0.00%)	(1.12%)
Permanent differences	0.60%	(7.95%)
R&D credits	(1.64%)	(3.16%)
Derecognition due to Sec. 382 and 383 limitations	54.08%	(0.00%)
Change in valuation allowance	(52.90%)	46.66%
Federal tax rate change	33.89%	(0.00%)
Other	(0.03%)	(0.43%)

Components of Company's Deferre

Components of Company's Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Accruals and reserves	$ 1,112	$ 1,137
Net operating loss carry forwards	11,519	25,944
R&D tax credit carry forwards	3,545	3,174
Fixed and intangible assets	89	114
Valuation Allowance	$ (16,265)	$ (30,369)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2007
Income Tax [Line Items]
Gross federal R&D tax credit-related deferred tax assets derecognized		$ 6,100,000
Unrecognized tax benefit		1,475,000	$ 1,539,000	$ 1,314,000
Tax-related penalties or interest recognized		$ 0	$ 0
Corporate tax rate		34.00%	34.00%
Decrease in deferred income tax assets		$ 7,300,000
Decrease in valuation allowance		7,300,000
Net effect of tax reform enactment		0
Scenario Forecast
Income Tax [Line Items]
Corporate tax rate	21.00%
Federal Income Tax
Income Tax [Line Items]
Net operating loss carryforwards		54,800,000	$ 68,300,000		$ 108,900,000
Tax credit carryforwards available to offset future federal tax liabilities		$ 100,000
Credit carryforward, expire period		Dec. 31, 2037
Net operating loss carryforward,derecognized					$ 22,900,000
Federal Income Tax | Beginning Year
Income Tax [Line Items]
Net operating loss carryforwards expiration year		2,025
Federal Income Tax | Ending Year
Income Tax [Line Items]
Net operating loss carryforwards expiration year		2,038
State Income Tax
Income Tax [Line Items]
Net operating loss carryforwards		$ 41,100,000	$ 46,600,000
Tax credit carryforwards available to offset future federal tax liabilities		$ 4,400,000
State Income Tax | Beginning Year
Income Tax [Line Items]
Net operating loss carryforwards expiration year		2,028
State Income Tax | Ending Year
Income Tax [Line Items]
Net operating loss carryforwards expiration year		2,038
CALIFORNIA
Income Tax [Line Items]
Net operating loss carryforwards		$ 37,700,000
Net operating loss carryforward,derecognized		$ 0

Unrecognized tax benefit (Detai

Unrecognized tax benefit (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Beginning Balance	$ 1,539	$ 1,314
Increase/(Decrease) of unrecognized tax benefits taken in prior years	(126)	6
Increase/(Decrease) of unrecognized tax benefits related to current year	62	219
Ending Balance	$ 1,475	$ 1,539

Collaborations - Additional Inf

Collaborations - Additional Information (Detail) - USD ($)	Sep. 16, 2013	Feb. 28, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 08, 2016
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Contract revenue			$ 1,018,000	$ 399,000
Pfizer Inc | Collaboration Agreement | Subsequent Event
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Milestone payment		$ 1,000,000
Pfizer Inc | Collaboration Agreement | Maximum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Contingent cash payments upon achievement of clinical, regulatory and commercial milestones					$ 17,500,000
ISU Abxis
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Contract revenue			300,000	400,000
Deferred revenue			200,000	300,000
Milestone payments recognized over the estimated remaining period of performance obligation			700,000	0
Milestone Payment Received			$ 900,000	$ 0
ISU Abxis | Up Front Payment
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Amount received for research and development process	$ 1,750,000

Detail of Other Income, Net (De

Detail of Other Income, Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Other Income And Expenses [Abstract]
Gain on sale of assets	$ (18)	$ 2,231
Change in derivative liability		1,156
Other Income, net	261	86
Total Other Income, net	$ 261	$ 3,473

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	Mar. 15, 2018	Feb. 15, 2018	Feb. 13, 2018	Dec. 22, 2017	Dec. 20, 2017	Apr. 12, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Mar. 16, 2016
Stockholders Equity Disclosure [Line Items]
Common stock, value of shares issued under sales agreement							$ 6,000	$ 1,000	$ 6,000
Net proceeds from sale of common stock				$ 9,700,000		$ 18,600,000	$ 5,336,000	$ 958,000
Warrants to purchase common stock						2,070,000
Warrants exercise price						$ 5.50		$ 145.11
Preferred stock, shares issued							3,680	0	3,680
Preferred stock, shares outstanding							3,680	0	3,680
Net proceeds allocated to common stock, preferred A stock and warrants							$ 18,563,000
Common stock price, per share						$ 5.28
Proceeds allocated to warrants, net						$ 5,000,000
Subsequent Event
Stockholders Equity Disclosure [Line Items]
Net proceeds from sale of common stock		$ 106,700,000
Preferred stock, shares outstanding	0
Overallotment Option
Stockholders Equity Disclosure [Line Items]
Warrants to purchase common stock						270,000
Series A Preferred Stock
Stockholders Equity Disclosure [Line Items]
Issuance of stock, shares						13,350
Conversion of each preferred stock to common stock						200
Number of shares converted							9,670
Preferred stock, shares issued							3,680		3,680
Preferred stock, shares outstanding							3,680		3,680
Net proceeds allocated to preferred stock							$ 10,100,000
Effective conversion price							$ 3.80		$ 3.80
Intrinsic value of preferred stock						$ 4,000,000
Effective percentage of conversion rights						100.00%
Common Stock
Stockholders Equity Disclosure [Line Items]
Issuance of stock, shares				1,105,263		1,470,000	439,880	39,743
Conversion of preferred stock to common stock							1,934,000	8
Common stock price, per share				$ 9.50
Firm commitment underwritten public offering shares					1,105,263
Common Stock | Subsequent Event
Stockholders Equity Disclosure [Line Items]
Issuance of stock, shares		3,382,352
Conversion of preferred stock to common stock	716,000
Common stock price, per share		$ 34
Firm commitment underwritten public offering shares			2,941,176
Common Stock | Overallotment Option
Stockholders Equity Disclosure [Line Items]
Issuance of stock, shares						540,000
Common Stock | Overallotment Option | Subsequent Event
Stockholders Equity Disclosure [Line Items]
Issuance of stock, shares		441,176
Capital on Demand Sales Agreement with Jones Trading Institutional Services LLC
Stockholders Equity Disclosure [Line Items]
Issuance of stock, shares									479,681
Common stock weighted average selling price									$ 13.55
Net proceeds from sale of common stock							$ 5,500,000		$ 6,300,000
Commission against additional paid-in capital									$ 200,000
Common stock available for sale							0		0
Capital on Demand Sales Agreement with Jones Trading Institutional Services LLC | Maximum
Stockholders Equity Disclosure [Line Items]
Common stock, value of shares issued under sales agreement										$ 6,500,000

Summary of Warrant Activity (De

Summary of Warrant Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2017	Apr. 12, 2017	Dec. 31, 2016
Warrants And Rights Note Disclosure [Abstract]
Number of Shares Underlying Warrants, Outstanding	12,039
Number of Shares Underlying Warrants, Issued	2,070,000
Number of Shares Underlying Warrants, Exercised	330,331
Number of Shares Underlying Warrants, Outstanding	1,751,708
Warrants Outstanding, Exercise Price		$ 5.50	$ 145.11
Warrants Issued, Exercise Price	$ 5.50
Warrants Exercised, Exercise Price	$ 5.50

Basic and Diluted Net Loss Per

Basic and Diluted Net Loss Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net loss attributable to common stockholders	$ (25,512)	$ (16,945)
Weighted-average number of shares used in computing net loss per share, basic and diluted	3,423,901	779,166
Net loss per share, basic and diluted	$ (7.45)	$ (21.75)

Anti-dilutive Security not Incl

Anti-dilutive Security not Included In Diluted per Share Calculations (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	3,346,332	293,796
Options To Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	821,741	140,990
Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	736,000
Common Stock Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	1,751,708	12,063
Redeemable Convertible Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	36,883	140,743

Anti-dilutive Security not In62

Anti-dilutive Security not Included In Diluted per Share Calculations (Parenthetical) (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Preferred stock, shares outstanding	3,680	0
Conversion of preferred stock to common stock	3,346,332	293,796
Series A Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Preferred stock, shares outstanding	3,680
Conversion of preferred stock to common stock	700,000

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($)

Mar. 15, 2018

Mar. 02, 2018

Feb. 19, 2018

Feb. 15, 2018

Feb. 13, 2018

Dec. 22, 2017

Dec. 20, 2017

Apr. 12, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Mar. 05, 2018

Feb. 21, 2018

Feb. 20, 2018

May 20, 2016

Subsequent Event [Line Items]

Common stock price, per share

$ 5.28

Net proceeds from sale of common stock

$ 9,700,000

$ 18,600,000

$ 5,336,000

$ 958,000

Redeemable convertible notes, outstanding balance

$ 5,085,000

$ 19,403,000

Preferred stock, shares outstanding

3,680

0

Number of warrants remaining

1,751,708

12,039

Proceeds received from warrants exercised

$ 1,817,000

Scenario Forecast

Subsequent Event [Line Items]

Proceeds received from warrants exercised

$ 9,300,000

AGC Biologics, Inc

Subsequent Event [Line Items]

Contractual obligation payments

$ 700,000

$ 3,800,000

Convertible Notes

Subsequent Event [Line Items]

Convertible notes, maturity date

Feb. 19, 2018

Common Stock

Subsequent Event [Line Items]

Firm commitment underwritten public offering shares

1,105,263

Issuance of stock, shares

1,105,263

1,470,000

439,880

39,743

Common stock price, per share

$ 9.50

Conversion of convertible securities, shares

1,934,000

8

Common Stock | Overallotment Option

Subsequent Event [Line Items]

Issuance of stock, shares

540,000

Subsequent Event

Subsequent Event [Line Items]

Net proceeds from sale of common stock

$ 106,700,000

Redeemable convertible notes, outstanding balance

$ 0

Preferred stock, shares outstanding

0

Remaining outstanding warrants called

254,628

Number of warrants remaining

45,628

Subsequent Event | AGC Biologics, Inc

Subsequent Event [Line Items]

Contractual obligation payments

$ 5,600,000

Subsequent Event | Convertible Notes

Subsequent Event [Line Items]

Convertible notes, maturity date

Feb. 19, 2018

Redeemable convertible notes, outstanding balance

$ 0

Subsequent Event | Common Stock

Subsequent Event [Line Items]

Firm commitment underwritten public offering shares

2,941,176

Issuance of stock, shares

3,382,352

Common stock price, per share

$ 34

Preferred stock called for conversion

3,580

Conversion of convertible securities, shares

716,000

Subsequent Event | Common Stock | Overallotment Option

Subsequent Event [Line Items]

Issuance of stock, shares

441,176