Molecular Templates (MTEM) 10-Q 31 Jul 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 28, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Trading Symbol	THLD
Entity Registrant Name	THRESHOLD PHARMACEUTICALS INC
Entity Central Index Key	1,183,765
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		71,591,918

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 16,468	$ 10,551
Marketable securities, current	300	13,000
Notes receivable	4,000	0
Prepaid expenses and other current assets	93	623
Total current assets	20,861	24,174
Property and equipment, net	0	109
Total assets	20,861	24,283
Current liabilities:
Accounts payable	319	822
Collaboration payable	0	129
Accrued clinical and development expenses	246	777
Accrued liabilities	1,915	888
Total current liabilities	2,480	2,616
Warrant liability	1,494	1,743
Deferred rent	0	36
Total liabilities	3,974	4,395
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock, $0.001 par value, 2,000,000 shares authorized; no shares issued and outstanding
Common stock, $0.001 par value, shares authorized: 150,000,000 shares; issued and outstanding: 71,591,918 shares at June 30, 2017 and 71,560,294 shares at December 31, 2016	72	72
Additional paid-in capital	374,278	373,352
Accumulated other comprehensive loss	0	(2)
Accumulated deficit	(357,463)	(353,534)
Total stockholders’ equity	16,887	19,888
Total liabilities and stockholders’ equity	$ 20,861	$ 24,283

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	71,591,918	71,560,294
Common stock, shares outstanding	71,591,918	71,560,294

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Revenue	$ 3,000	$ 0	$ 3,000	$ 0
Operating expenses:
Research and development	1,115	4,016	2,705	10,021
General and administrative	1,687	1,892	4,540	4,141
Total operating expenses	2,802	5,908	7,245	14,162
Income (loss) from operations	198	(5,908)	(4,245)	(14,162)
Interest income (expense), net	34	40	67	72
Other income (expense), net	913	(996)	249	(626)
Net income (loss)	1,145	(6,864)	(3,929)	(14,716)
Other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale securities	(1)	4	(2)	26
Comprehensive income (loss)	$ 1,144	$ (6,860)	$ (3,931)	$ (14,690)
Net income (loss) per share:
Basic	$ 0.02	$ (0.10)	$ (0.05)	$ (0.21)
Diluted	$ 0.02	$ (0.10)	$ (0.05)	$ (0.21)
Weighted average number of shares used in net income (loss) per share calculations:
Basic	71,592	71,511	71,584	71,500
Diluted	71,621	71,511	71,584	71,500

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net loss	$ (3,929)	$ (14,716)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	25	305
Gain on sale of property and equipment	(21)	(51)
Stock-based compensation expense	919	1,645
Change in common stock warrant fair value	(249)	626
Changes in operating assets and liabilities:
Collaboration receivable/payable	(129)	970
Prepaid expenses and other assets	530	1,305
Accounts payable	(503)	2,351
Accrued clinical and development expenses	(531)	(4,737)
Accrued liabilities	1,027	(2,653)
Deferred rent	(36)	(44)
Net cash used in operating activities	(2,897)	(14,999)
Cash flows from investing activities:
Issuance of promissory notes to Molecular Templates, Inc.	(4,000)	0
Purchases of marketable securities	(299)	(13,454)
Proceeds from sale of property and equipment	100	61
Proceeds from maturities of marketable securities	13,006	31,192
Net cash provided by investing activities	8,807	17,799
Cash flows from financing activities:
Proceeds from issuance of common stock and warrants	7	13
Net cash provided by financing activities	7	13
Net increase in cash and cash equivalents	5,917	2,813
Cash and cash equivalents, beginning of period	10,551	9,589
Cash and cash equivalents, end of period	$ 16,468	$ 12,402

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Organization and Summary of Significant Accounting Policies	NOTE 1 — ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES The Company Threshold Pharmaceuticals, Inc. (the “Company”) is a biotechnology company using its expertise in the tumor microenvironment to discover and develop therapeutic agents that selectively target tumor cells for the treatment of patients living with cancer. The Company has no commercial products, and the Company announced at the end of 2015 that its lead product candidate, evofosfamide, a novel, hypoxia-activated prodrug of a bis-alkylating agent, did not meet its primary endpoint of demonstrating a statistically significant improvement in two pivotal Phase 3 clinical trials. In 2016, the Company engaged a financial and strategic advisor to explore a range of alternatives to enhance stockholder value, including but not limited to business combination and/or partnership opportunities, as well as a distribution of a significant amount of cash to stockholders, and dissolution of the Company. In March 2017, the Company entered into a definitive agreement for a merger with Molecular Therapeutics, Inc. See Note 3 regarding this transaction. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America for pursuant to the requirements of the Securities and Exchange Commission (“SEC”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States of America for complete financial statements. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements. In the opinion of management, all adjustments, consisting only of normal recurring adjustments necessary for the fair presentation of results for the periods presented, have been included. The results of operations of any interim period are not necessarily indicative of the results of operations for the full year or any other interim period. The preparation of condensed consolidated financial statements requires management to make estimates and assumptions that affect the recorded amounts reported therein. A change in facts or circumstances surrounding the estimate could result in a change to estimates and impact future operating results. The unaudited condensed consolidated financial statements and related disclosures have been prepared with the presumption that users of the interim unaudited condensed consolidated financial statements have read or have access to the audited consolidated financial statements for the preceding fiscal year. Accordingly, these unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2016 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 27, 2017. The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, and reflect the elimination of intercompany accounts and transactions. In March 2016, the FASB issued an accounting standard update, which simplifies several aspects of the accounting for share-based payments, including immediate recognition of all excess tax benefits and deficiencies in the income statement, changing the threshold to qualify for equity classification up to the employees' maximum statutory tax rates, allowing an entity-wide accounting policy election to either estimate the number of awards that are expected to vest or account for forfeitures as they occur, and clarifying the classification on the statement of cash flows for the excess tax benefit and employee taxes paid when an employer withholds shares for tax-withholding purposes. The Company adopted the standard effective January 1, 2017 and the adoption did not have a material effect on its condensed consolidated financial statement. In November 2015, the FASB issued an accounting standard update for the presentation of deferred income taxes. Under this new guidance, deferred tax liabilities and assets should be classified as noncurrent in a classified balance sheet. The update is effective for the Company beginning in the first quarter of fiscal year 2017 with early adoption permitted as of the beginning of an interim or annual reporting period. Additionally, this guidance may be applied either prospectively or retrospectively to all periods presented. We adopted the standard in the first quarter of 2017 and it did not have a material impact to our consolidated financial statements. Revenue Recognition The Company recognizes revenue in accordance with ASC 605 “Revenue Recognition”, subtopic ASC 605-25 “Revenue with Multiple Element Arrangements” and subtopic ASC 605-28 “Revenue Recognition-Milestone Method”, which provides accounting guidance for revenue recognition for arrangements with multiple deliverables and guidance on defining the milestone and determining when the use of the milestone method of revenue recognition for research and development transactions is appropriate, respectively. The Company’s revenues during three months ended June 30, 2017 was related to its asset transfer and related license agreement (the “Asset Transfer Agreement”) with OBI Pharma Inc. (“OBI”), which was entered into on May 31, 2017 for our preclinical candidate TH-3424. The Asset Transfer Agreement with OBI provided for nonrefundable payments to the Company upon the transfer of the Company’s rights and obligation to OBI for TH-3424. The Company completed the transfer of its rights and obligations related to TH-3424 to OBI on June 16, 2017 and has no further obligations under the Asset Transfer Agreement. The Company recognized revenue when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price is fixed or determinable, and collectability is reasonably assured.

Net Income (Loss) Per Share

Net Income (Loss) Per Share	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Net Income (Loss) Per Share	NOTE 2 — NET INCOME (LOSS) PER SHARE Basic net income (loss) per common share is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. Diluted net (income) loss per share is computed by giving effect to all potential dilutive common shares, including outstanding options and warrants. Potential dilutive common shares also include the dilutive effect of the common stock underlying in-the-money stock options and warrants that were calculated based on the average share price for each period using the treasury stock method. Under the treasury stock method, the exercise price of an option or warrant is assumed to be used to repurchase shares in the current period. In addition, the average amount of compensation cost for in-the-money options, if any, for future service that the Company has not yet recognized when the option is exercised, is also assumed to repurchase shares in the current period. A reconciliation of the numerator and denominator used in the calculation is as follows (in thousands, except per share amounts): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Numerator: Net income (loss) $ 1,145 $ (6,864 ) $ (3,929 ) $ (14,716 ) Denominator: Weighted average common shares outstanding - basic 71,592 71,511 71,584 71,500 Dilutive effect of equity incentive awards 29 — — — Weighted-average common shares outstanding and dilutive potential common shares — diluted 71,621 71,511 71,584 71,500 Net income (loss) per share: Basic $ 0.02 $ (0.10 ) $ (0.05 ) $ (0.21 ) Diluted $ 0.02 $ (0.10 ) $ (0.05 ) $ (0.21 ) The following outstanding warrants, options and purchase rights under the Company’s 2004 Employee Stock Purchase Plan (“2004 Purchase Plan”) were excluded from the computation of diluted net loss per share for the periods presented because including them would have had an antidilutive effect (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Shares issuable upon exercise of warrants 8,300 8,300 8,300 8,300 Shares issuable upon exercise of stock options 10,542 11,635 10,732 11,635 Shares issuable related to the 2004 Purchase Plan 21 42 21 42

Merger Agreement with Molecular

Merger Agreement with Molecular Templates	6 Months Ended
	Jun. 30, 2017
Business Combinations [Abstract]
Merger Agreement with Molecular Templates	NOTE 3 — MERGER AGREEMENT WITH MOLECULAR TEMPLATES In March 2017, the Company entered into a definitive Merger Agreement (“Merger Agreement”), with Molecular Templates, Inc. (“Molecular Templates”), a private company incorporated and registered in the United States and the shareholders of Molecular Templates, pursuant to which the shareholders of Molecular Templates will become the majority owners of the Company. The number of shares of common stock of the Company to be issued in respect of each Molecular Templates share will be based upon the relative stipulated values of each of the Company and Molecular Templates as determined pursuant to the Merger Agreement. The stipulated value of the Company is subject to downward adjustment based upon the Company’s net cash balance at the closing of the transaction. Assuming that no such adjustment is applicable, immediately following the closing of the transaction, Molecular Templates equity holders are expected to own approximately 65.6% of the outstanding common stock of the Company on a fully-diluted basis. Consummation of the transaction is subject to certain closing conditions, including, among other things, approval by the stockholders of the Company of the transactions contemplated by the Merger Agreement and related matters. The Merger Agreement contains certain termination rights for both the Company and Molecular Templates, and further provides that, upon termination of the Merger Agreement under specified circumstances, the Company may be required to pay Molecular Templates a termination fee of $0.8 million. Any strategic transaction that is completed ultimately may not deliver the anticipated benefits or enhance shareholder value. In connection with execution of the Merger Agreement, the Company made a bridge loan to Molecular Templates pursuant to a note purchase agreement and promissory notes (the “Notes”) up to an aggregate principal amount of $4.0 million with an initial closing held on March 24, 2017 for a principal amount of $2.0 million and an additional $2.0 million at the second closing held on June 1, 2017. If the Merger Agreement is terminated prior to the maturity date, which is the one year anniversary from the signing of the note purchase agreement, of the Notes, the outstanding principal of the Notes plus all accrued and unpaid interest shall become due and payable upon the earlier of (i) the consummation of a qualified financing by Molecular Templates of at least $10.0 million, (ii) the occurrence of a Molecular Templates liquidity event, or (iii) the four-month anniversary of the termination of the Merger Agreement, and such amounts shall be credited against any termination fees owed by the Company to Molecular Templates pursuant to the Merger Agreement. In addition on March 16, 2017, the Company and Molecular Templates received from Longitude Venture Partners III, L.P. (“Longitude”) an Equity Commitment Letter (the “Commitment Letter”), pursuant to which, immediately following the Closing of the Merger, Longitude will purchase $20 million of equity securities in the Company. Longitude’s investment is subject to certain conditions, including the Closing of the Merger and the Company having secured commitments from additional investors for the purchase of an additional $20 million of such securities (the “Financing”). Subsequent to the execution of the merger agreement, Threshold and Molecular have obtained equity commitment letters in a form substantially similar to the equity commitment letter with Longitude from additional investors for an additional $20.0 million, such that the aggregate size of the concurrent financing is expected to be approximately $40.0 million. The Financing will be accomplished in a private placement exempt from registration under Section 4(a)(2) and Regulation D under the Securities Act of 1933, as amended (the “Securities Act”), and the rules promulgated thereunder. The closing of the Merger is not contingent upon the completion of this Financing. Furthermore, on June 23, 2017, the Company and Molecular Templates entered into a stock purchase agreement with Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Ltd. (“Takeda”), pursuant to which Takeda will purchase approximately $20.0 million of shares of common stock of the combined company at a (pre-reverse split) purchase price per share of approximately $0.61 per share, provided that Takeda’s investment amount will be reduced to the extent its beneficial ownership post-closing would exceed 19.0% of the total outstanding shares of the combined company. Such transaction will be a private placement and is referred to herein as the Takeda equity financing. The closing of the Takeda equity financing is conditioned upon the closing of the merger and the concurrent financing, as well as certain other conditions.

Agreement with OBI Pharma

Agreement with OBI Pharma	6 Months Ended
	Jun. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Agreement with OBI Pharma	NOTE 4 —AGREEMENT WITH OBI PHARMA On May 31, 2017, the Company, and OBI, entered into an Asset Transfer Agreement pursuant to which the Company agreed to sell to OBI certain rights to TH-3424. The assets purchased by OBI pursuant to the Asset Transfer Agreement included certain specified intellectual property (the “Assigned Intellectual Property”), as well as assumed contracts and documentation, in each case, related to TH-3424. In connection with the sale of TH-3424, OBI also assumed certain liabilities and obligations of the Company arising out of or related to certain of the assumed contracts. In addition, the Company granted to OBI a non-exclusive, nontransferable, fully paid-up license of certain of its intellectual property rights for use by OBI in the development of TH-3424. The transfer to OBI of the Threshold’s rights and obligations was completed on June 16, 2017. Pursuant to the Asset Transfer Agreement, OBI paid the Company $3.0 million. The Company immediately recognized the $3.0 million of non-refundable payments as revenue as the Company had no further obligations under the Asset Transfer Agreement upon the completion of the transfer of its rights and obligations to OBI. Under the Asset Transfer Agreement, the Company will be entitled to reacquire its rights from OBI for no consideration if OBI breaches its payment obligations under the Agreement.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2017
Equity [Abstract]
Stockholders' Equity	NOTE 5 — STOCKHOLDERS’ EQUITY Common Stock Warrant Valuation The Company accounts for its common stock warrants under guidance in ASC 815 that clarifies the determination of whether an instrument (or an embedded feature) is indexed to an entity’s own stock, which would qualify for classification as liabilities. The guidance requires the Company’s outstanding warrants to be classified as liabilities and to be fair valued at each reporting period, with the changes in fair value recognized as other income (expense) in the Company’s consolidated statements of operations. At both June 30, 2017 and December 31, 2016 the Company had warrants outstanding to purchase 8.3 million shares of common stock, having an exercise price of $3.62 per share, which warrants were issued by the Company in the Company’s February 2015 public offering of common stock and warrants. The fair value of these warrants on June 30, 2017 and December 31, 2016 was determined using a Black-Scholes model with the following key level 3 inputs: June 30, 2017 December 31, 2016 Risk-free interest rate 1.55 % 1.93 % Expected life (in years) 2.64 3.13 Dividend yield — — Volatility 147 % 135 % Stock price $ 0.39 $ 0.44 During the three and six months ended June 30, 2017 the change in fair value of $0.9 million and $0.2 million, respectively, of noncash income related to the February 2015 warrants was recorded as other income (expense) in the Company’s consolidated statement of operations. The following table sets forth the Company’s financial liabilities, related to warrants issued in the February 2015 offering, subject to fair value measurements as of June 30, 2017 and December 31, 2016: Basis of Fair Value Measurements (in thousands) Fair Value as of June 30, 2017 Level 1 Level 2 Level 3 February 2015 warrants $ 1,494 $ — $ — $ 1,494 Basis of Fair Value Measurements (in thousands) Fair Value as of December 31, 2016 Level 1 Level 2 Level 3 February 2015 warrants 1,743 — — 1,743 The following table is a reconciliation of the warrant liability measured at fair value using level 3 inputs (in thousands): Warrant Liability Balance at December 31, 2016 $ 1,743 Change in fair value of common stock warrants during six months ended June 30, 2017 (249 ) Balance at June 30, 2017 $ 1,494

Stock Based Compensation

Stock Based Compensation	6 Months Ended
	Jun. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Based Compensation	NOTE 6 — STOCK BASED COMPENSATION The Company recognizes stock-based compensation in accordance with ASC 718, “Compensation—Stock Compensation.” Stock-based compensation expense, which consists of the compensation cost for employee stock options and the 2004 Purchase Plan, and the value of options issued to non-employees for services rendered, was allocated to research and development and general and administrative expenses in the unaudited consolidated statements of operations for the three and six months ended June 30, 2017 and 2016 as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Amortization of stock-based compensation: Research and development $ 143 $ 306 $ 294 $ 624 General and administrative 271 496 625 1,021 $ 414 $ 802 $ 919 $ 1,645 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. This fair value is being amortized ratably over the requisite service periods of the awards, which is generally the vesting period. The fair value of employee stock options and employee purchase rights under the 2004 Purchase Plan was estimated using the following weighted-average assumptions for the three and six months ended June 30, 2017 and 2016: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Employee Stock Options: Risk-free interest rate — 1.08 % — 1.60 % Expected term (in years) — 5.27 — 5.97 Dividend yield — — — — Volatility — 109 % — 108 % Weighted-average fair value of stock options granted — $ 0.30 — $ 0.44 Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Employee Stock Purchase Plan (ESPP): Risk-free interest rate 0.56 % 0.56 % 0.56 % 0.56 % Expected term (in years) 1.24 1.24 1.24 1.24 Dividend yield — — — — Volatility 161 % 161 % 161 % 161 % Weighted-average fair value of ESPP purchase rights $ 0.22 $ 0.22 $ 0.22 $ 0.22 To determine the expected term of the Company’s employee stock options granted, the Company utilized the simplified approach as defined by SEC Staff Accounting Bulletin No. 107, “Share-Based Payment” Employee Stock-based Compensation Expense As required by ASC 718, the Company recognized $0.4 million and $0.9 million of stock-based compensation expense related to stock options and purchase rights under the Company’s equity incentive plans and 2004 Purchase Plan for the three and six months ended June 30, 2017 and $0.8 million and $1.6 million of stock-based compensation for the three and six months ended June 30, 2016. As of June 30, 2017, the total unrecognized compensation cost related to unvested stock-based awards granted to employees under the Company’s equity incentive plans was approximately $2.4 million before forfeitures. This cost will be recorded as compensation expense on a ratable basis over the remaining weighted average requisite service period of approximately 2.1 years. Equity Incentive Plans Equity Incentive Plans At June 30, 2017, 1,754,229 shares were authorized and available for issuance under the 2014 Equity Incentive Plan. The following table summarizes stock option activity under the Company’s equity incentive plans: Options Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at December 31, 2016 10,941,745 $ 3.00 — — Granted — $ — — — Exercised — $ — — — Forfeitures (209,485 ) $ 1.37 — — Outstanding at June 30, 2017 10,732,260 $ 3.03 4.91 $ 2,730 Vested and expected to vest June 30, 2017 10,689,426 $ 3.04 4.89 $ 2,730 Exercisable at June 30, 2017 8,640,234 $ 3.38 4.07 $ 2,730 No stock options were exercised during the six months ended June 30, 2017. The Company issues new shares of common stock upon exercise of options. As there were no exercises, there was no tax benefit realized by the Company. 2004 Employee Stock Purchase Plan On January 1, 2017, an additional 100,000 shares was authorized for issuance under the 2004 Purchase Plan pursuant to the annual automatic increase to the authorized shares under the 2004 Purchase Plan. For the six months ended June 30, 2017, plan participants had purchased 31,624 shares at an average purchase price of $0.25 for total cash proceeds of $7,000. At June 30, 2017, 203,165 shares were authorized and available for issuance under the 2004 Purchase Plan.

Marketable Securities and Fair

Marketable Securities and Fair Value	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Marketable Securities and Fair Value	NOTE 7 —MARKETABLE SECURITIES AND FAIR VALUE The Company accounts for its marketable securities in accordance with ASC 820 “Fair Value Measurements and Disclosures.” Level 1 —Quoted prices in active markets for identical assets or liabilities. Level 2 —Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, 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 —Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company utilizes the market approach to measure fair value for its financial assets and liabilities. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities. For Level 2 securities that have market prices from multiples sources, a “consensus price” or a weighted average price for each of these securities can be derived from a distribution-curve-based algorithm which includes market prices obtained from a variety of industrial standard data providers (e.g. Bloomberg), security master files from large financial institutions, and other third-party sources. Level 2 securities with short maturities and infrequent secondary market trades are typically priced using mathematical calculations adjusted for observable inputs when available. The following table sets forth the Company’s financial assets (cash equivalents and marketable securities) at fair value on a recurring basis as of June 30, 2017 and December 31, 2016: Basis of Fair Value Measurements (in thousands) Fair Value as of June 30, 2017 Level 1 Level 2 Level 3 Money market funds $ 14,103 $ 14,103 $ — $ — Commercial paper 299 — 299 — Total cash equivalents and marketable securities $ 14,402 $ 14,103 $ 299 $ — Basis of Fair Value Measurements (in thousands) Fair Value as of December 31, 2016 Level 1 Level 2 Level 3 Money market funds $ 2,746 $ 2,746 $ — $ — Corporate debt securities 4,206 — 4,206 — Government securities 5,299 — 5,299 — Commercial paper 10,966 — 10,966 — Total cash equivalents and marketable securities $ 23,217 $ 2,746 $ 20,471 $ — The Company invests in highly-liquid, investment-grade securities. The following is a summary of the Company’s available-for-sale securities at June 30, 2017 and December 31, 2016: As of June 30, 2017 (in thousands): Cost Basis Unrealized Gain Unrealized Loss Fair Value Money market funds $ 14,103 $ — $ — $ 14,103 Commercial paper 299 — — 299 14,402 — — 14,402 Less cash equivalents 14,103 — — 14,103 Total marketable securities $ 299 $ — $ — $ 299 As of December 31, 2016 (in thousands): Cost Basis Unrealized Gain Unrealized Loss Fair Value Money market funds $ 2,746 $ — $ — $ 2,746 Corporate debt securities 4,208 — (2 ) 4,206 U.S. Government securities 5,299 1 (1 ) 5,299 Commercial paper 10,966 — — 10,966 23,219 1 (3 ) 23,217 Less cash equivalents 10,217 — — 10,217 Total marketable securities $ 13,002 $ 1 $ (3 ) $ 13,000 There were no realized gains or losses in the three and six months ended June 30, 2017 and 2016, respectively. As of June 30, 2017, the weighted average maturity for the Company’s available for sale securities was less than 1.0 month, with the longest maturity being July 2017. The Company does not intend to sell the investments that are in an unrealized loss position, and it is unlikely that the Company will be required to sell the investments before recovery of their amortized cost basis, which may be maturity. There were no marketable securities with unrealized losses at June 30, 2017. The Company determined the fair value of the liability associated with its February 2015 warrants to purchase in aggregate 8.3 million shares of outstanding common stock using a Black-Scholes Model. See detailed discussion in Note 4 —

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE 7 — COMMITMENTS AND CONTINGENCIES Indemnification The Company enters into indemnification provisions under its agreements with other companies in the ordinary course of business, including business partners, contractors and parties performing its clinical trials. Pursuant to these arrangements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified parties for losses suffered or incurred by the indemnified party as a result of the Company’s activities. The duration of these indemnification agreements is generally perpetual. The maximum potential amount of future payments the Company could be required to make under these agreements is not determinable. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements. As a result, the Company believes the estimated fair value of these agreements is minimal. The Company maintains commercial general liability insurance and products liability insurance to offset certain of its potential liabilities under these indemnification provisions. Accordingly, the Company has not recognized any liabilities relating to these agreements as of June 30, 2017. The Company’s bylaws provide that it is required to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers, other than liabilities arising from willful misconduct of a culpable nature, to the fullest extent permissible by applicable law; and to advance their expenses incurred as a result of any proceeding against them as to which they could be indemnified.

Organization and Summary of S14

Organization and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Revenue Recognition	Revenue Recognition The Company recognizes revenue in accordance with ASC 605 “Revenue Recognition”, subtopic ASC 605-25 “Revenue with Multiple Element Arrangements” and subtopic ASC 605-28 “Revenue Recognition-Milestone Method”, which provides accounting guidance for revenue recognition for arrangements with multiple deliverables and guidance on defining the milestone and determining when the use of the milestone method of revenue recognition for research and development transactions is appropriate, respectively. The Company’s revenues during three months ended June 30, 2017 was related to its asset transfer and related license agreement (the “Asset Transfer Agreement”) with OBI Pharma Inc. (“OBI”), which was entered into on May 31, 2017 for our preclinical candidate TH-3424. The Asset Transfer Agreement with OBI provided for nonrefundable payments to the Company upon the transfer of the Company’s rights and obligation to OBI for TH-3424. The Company completed the transfer of its rights and obligations related to TH-3424 to OBI on June 16, 2017 and has no further obligations under the Asset Transfer Agreement. The Company recognized revenue when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price is fixed or determinable, and collectability is reasonably assured.

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Reconciliation of Numerator and Denominator	A reconciliation of the numerator and denominator used in the calculation is as follows (in thousands, except per share amounts): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Numerator: Net income (loss) $ 1,145 $ (6,864 ) $ (3,929 ) $ (14,716 ) Denominator: Weighted average common shares outstanding - basic 71,592 71,511 71,584 71,500 Dilutive effect of equity incentive awards 29 — — — Weighted-average common shares outstanding and dilutive potential common shares — diluted 71,621 71,511 71,584 71,500 Net income (loss) per share: Basic $ 0.02 $ (0.10 ) $ (0.05 ) $ (0.21 ) Diluted $ 0.02 $ (0.10 ) $ (0.05 ) $ (0.21 )
Warrants, Options and Purchase Rights Excluded from Computation of Diluted Net Loss Per Share	The following outstanding warrants, options and purchase rights under the Company’s 2004 Employee Stock Purchase Plan (“2004 Purchase Plan”) were excluded from the computation of diluted net loss per share for the periods presented because including them would have had an antidilutive effect (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Shares issuable upon exercise of warrants 8,300 8,300 8,300 8,300 Shares issuable upon exercise of stock options 10,542 11,635 10,732 11,635 Shares issuable related to the 2004 Purchase Plan 21 42 21 42

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2017
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Financial Liabilities Subject to Fair Value Measurements	The following table sets forth the Company’s financial liabilities, related to warrants issued in the February 2015 offering, subject to fair value measurements as of June 30, 2017 and December 31, 2016: Basis of Fair Value Measurements (in thousands) Fair Value as of June 30, 2017 Level 1 Level 2 Level 3 February 2015 warrants $ 1,494 $ — $ — $ 1,494 Basis of Fair Value Measurements (in thousands) Fair Value as of December 31, 2016 Level 1 Level 2 Level 3 February 2015 warrants 1,743 — — 1,743
Reconciliation of Warrant Liability Measured at Fair Value	The following table is a reconciliation of the warrant liability measured at fair value using level 3 inputs (in thousands): Warrant Liability Balance at December 31, 2016 $ 1,743 Change in fair value of common stock warrants during six months ended June 30, 2017 (249 ) Balance at June 30, 2017 $ 1,494
February 2015 Warrants
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Outstanding Warrants Valuation Assumption	The fair value of these warrants on June 30, 2017 and December 31, 2016 was determined using a Black-Scholes model with the following key level 3 inputs: June 30, 2017 December 31, 2016 Risk-free interest rate 1.55 % 1.93 % Expected life (in years) 2.64 3.13 Dividend yield — — Volatility 147 % 135 % Stock price $ 0.39 $ 0.44

Stock Based Compensation (Table

Stock Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation Expense	Stock-based compensation expense, which consists of the compensation cost for employee stock options and the 2004 Purchase Plan, and the value of options issued to non-employees for services rendered, was allocated to research and development and general and administrative expenses in the unaudited consolidated statements of operations for the three and six months ended June 30, 2017 and 2016 as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Amortization of stock-based compensation: Research and development $ 143 $ 306 $ 294 $ 624 General and administrative 271 496 625 1,021 $ 414 $ 802 $ 919 $ 1,645
Weighted-Average Fair Value Valuation Assumptions	The fair value of employee stock options and employee purchase rights under the 2004 Purchase Plan was estimated using the following weighted-average assumptions for the three and six months ended June 30, 2017 and 2016: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Employee Stock Options: Risk-free interest rate — 1.08 % — 1.60 % Expected term (in years) — 5.27 — 5.97 Dividend yield — — — — Volatility — 109 % — 108 % Weighted-average fair value of stock options granted — $ 0.30 — $ 0.44 Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Employee Stock Purchase Plan (ESPP): Risk-free interest rate 0.56 % 0.56 % 0.56 % 0.56 % Expected term (in years) 1.24 1.24 1.24 1.24 Dividend yield — — — — Volatility 161 % 161 % 161 % 161 % Weighted-average fair value of ESPP purchase rights $ 0.22 $ 0.22 $ 0.22 $ 0.22
Stock Option Activity Under Equity Incentive Plan	The following table summarizes stock option activity under the Company’s equity incentive plans: Options Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at December 31, 2016 10,941,745 $ 3.00 — — Granted — $ — — — Exercised — $ — — — Forfeitures (209,485 ) $ 1.37 — — Outstanding at June 30, 2017 10,732,260 $ 3.03 4.91 $ 2,730 Vested and expected to vest June 30, 2017 10,689,426 $ 3.04 4.89 $ 2,730 Exercisable at June 30, 2017 8,640,234 $ 3.38 4.07 $ 2,730

Marketable Securities and Fai18

Marketable Securities and Fair Value (Tables)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Financial Assets at Fair Value on Recurring Basis	The following table sets forth the Company’s financial assets (cash equivalents and marketable securities) at fair value on a recurring basis as of June 30, 2017 and December 31, 2016: Basis of Fair Value Measurements (in thousands) Fair Value as of June 30, 2017 Level 1 Level 2 Level 3 Money market funds $ 14,103 $ 14,103 $ — $ — Commercial paper 299 — 299 — Total cash equivalents and marketable securities $ 14,402 $ 14,103 $ 299 $ — Basis of Fair Value Measurements (in thousands) Fair Value as of December 31, 2016 Level 1 Level 2 Level 3 Money market funds $ 2,746 $ 2,746 $ — $ — Corporate debt securities 4,206 — 4,206 — Government securities 5,299 — 5,299 — Commercial paper 10,966 — 10,966 — Total cash equivalents and marketable securities $ 23,217 $ 2,746 $ 20,471 $ —
Summary of Company's Available-for-Sale Securities	The Company invests in highly-liquid, investment-grade securities. The following is a summary of the Company’s available-for-sale securities at June 30, 2017 and December 31, 2016: As of June 30, 2017 (in thousands): Cost Basis Unrealized Gain Unrealized Loss Fair Value Money market funds $ 14,103 $ — $ — $ 14,103 Commercial paper 299 — — 299 14,402 — — 14,402 Less cash equivalents 14,103 — — 14,103 Total marketable securities $ 299 $ — $ — $ 299 As of December 31, 2016 (in thousands): Cost Basis Unrealized Gain Unrealized Loss Fair Value Money market funds $ 2,746 $ — $ — $ 2,746 Corporate debt securities 4,208 — (2 ) 4,206 U.S. Government securities 5,299 1 (1 ) 5,299 Commercial paper 10,966 — — 10,966 23,219 1 (3 ) 23,217 Less cash equivalents 10,217 — — 10,217 Total marketable securities $ 13,002 $ 1 $ (3 ) $ 13,000

Net Income (Loss) Per Share - R

Net Income (Loss) Per Share - Reconciliation of Numerator and Denominator (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator:
Net income (loss)	$ 1,145	$ (6,864)	$ (3,929)	$ (14,716)
Denominator:
Weighted average common shares outstanding - basic	71,592	71,511	71,584	71,500
Dilutive effect of equity incentive awards	29	0	0	0
Weighted-average common shares outstanding and dilutive potential common shares — diluted	71,621	71,511	71,584	71,500
Net income (loss) per share:
Basic	$ 0.02	$ (0.10)	$ (0.05)	$ (0.21)
Diluted	$ 0.02	$ (0.10)	$ (0.05)	$ (0.21)

Net Income (Loss) Per Share - W

Net Income (Loss) Per Share - Warrants, Options and Purchase Rights Excluded from Computation of Diluted Net Loss Per Share (Detail) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Shares issuable	8,300	8,300	8,300	8,300
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Shares issuable	10,542	11,635	10,732	11,635
2004 Purchase Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Shares issuable	21	42	21	42

Merger Agreement with Molecul21

Merger Agreement with Molecular Templates - Additional Information (Detail) - USD ($)	Jun. 23, 2017	Mar. 16, 2017	Jun. 01, 2017	Mar. 24, 2017
Longitude Ventures and Other Investors
Business Acquisition [Line Items]
Commitment to purchase equity securities under equity commitment letter		$ 20,000,000
Amount of additional equity commitments to be secured for equity commitment letter		20,000,000
Expected aggregate amount of concurrent financing		$ 40,000,000
Merger Agreement | Molecular Templates Inc
Business Acquisition [Line Items]
Molecular Templates equity holders ownership interest		65.60%
Termination fee		$ 800,000
Merger Agreement | Molecular Templates Inc | Minimum
Business Acquisition [Line Items]
Amount of qualified financing contingent for repayment of promissory note		10,000,000
Merger Agreement | Molecular Templates Inc | Notes
Business Acquisition [Line Items]
Aggregate principal amount		$ 4,000,000
Principal amount			$ 2,000,000	$ 2,000,000
Merger Agreement | Molecular Templates Inc and Millennium Pharmaceuticals Inc
Business Acquisition [Line Items]
Expected contingent proceeds from stock purchase agreement with Millennium Pharmaceuticals, Inc.	$ 20,000,000
Per share price (pre-reverse split) at which stock will sold to Millennium Pharmaceuticals, Inc.	$ 0.61
Merger Agreement | Molecular Templates Inc and Millennium Pharmaceuticals Inc | Minimum
Business Acquisition [Line Items]
Millennium Pharmaceuticals, post closing beneficial ownership percentage limitation	19.00%

Agreement with OBI Pharma - Add

Agreement with OBI Pharma - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 16, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue		$ 3,000	$ 0	$ 3,000	$ 0
OBI Pharma
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Nonrefundable payments received for sale of TH-3424 rights and obligations	$ 3,000
Revenue	$ 3,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Class Of Warrant Or Right [Line Items]
Warrants to purchase shares of common stock	8.3	8.3
February 2015 Warrants
Class Of Warrant Or Right [Line Items]
Warrants to purchase shares of common stock	8.3	8.3	8.3
Warrant exercise price	$ 3.62	$ 3.62	$ 3.62
February 2015 Warrants | Warrants
Class Of Warrant Or Right [Line Items]
Change in fair value of common stock warrants	$ (0.9)	$ (0.2)

Stockholders' Equity - Outstand

Stockholders' Equity - Outstanding Warrants Valuation Assumption (Detail) - February 2015 Warrants - $ / shares	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk-free interest rate	1.55%	1.93%
Expected life (in years)	2 years 7 months 21 days	3 years 1 month 16 days
Dividend yield	0.00%	0.00%
Volatility	147.00%	135.00%
Stock price	$ 0.39	$ 0.44

Stockholders' Equity - Financia

Stockholders' Equity - Financial Liabilities Subject to Fair Value Measurements (Detail) - February 2015 Warrants - Warrants - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Financial liabilities subject to fair value measurements	$ 1,494	$ 1,743
Basis of Fair Value Measurements, Level 3
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Financial liabilities subject to fair value measurements	$ 1,494	$ 1,743

Stockholders' Equity - Reconcil

Stockholders' Equity - Reconciliation of Warrant Liability Measured at Fair Value (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Change in fair value of common stock warrants	$ (249)	$ 626
Level 3 Inputs
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	1,743
Change in fair value of common stock warrants	(249)
Ending Balance	$ 1,494

Stock Based Compensation - Stoc

Stock Based Compensation - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Amortization of stock-based compensation	$ 414	$ 802	$ 919	$ 1,645
Research and Development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Amortization of stock-based compensation	143	306	294	624
General and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Amortization of stock-based compensation	$ 271	$ 496	$ 625	$ 1,021

Stock Based Compensation - Weig

Stock Based Compensation - Weighted-Average Fair Value Valuation Assumptions (Detail) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	0.00%	1.08%	0.00%	1.60%
Expected term (in years)	0 years	5 years 3 months 8 days	0 years	5 years 11 months 19 days
Dividend yield	0.00%	0.00%	0.00%	0.00%
Volatility	0.00%	109.00%	0.00%	108.00%
Weighted-average fair value of stock options granted	$ 0	$ 0.30	$ 0	$ 0.44
Employee Stock Purchase Plan (ESPP)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	0.56%	0.56%	0.56%	0.56%
Expected term (in years)	1 year 2 months 27 days	1 year 2 months 27 days	1 year 2 months 27 days	1 year 2 months 27 days
Dividend yield	0.00%	0.00%	0.00%	0.00%
Volatility	161.00%	161.00%	161.00%	161.00%
Weighted-average fair value of ESPP purchase rights	$ 0.22	$ 0.22	$ 0.22	$ 0.22

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Detail) - USD ($)	Jan. 01, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense		$ 414,000	$ 802,000	$ 919,000	$ 1,645,000
Unrecognized compensation cost related to unvested stock-based awards granted to employees under the stock option plans		$ 2,400,000		$ 2,400,000
Unrecognized compensation cost related to unvested stock-based awards granted to employees under the stock option plans, period for recognition				2 years 1 month 6 days
Stock options exercised				0
Tax benefit realized upon exercise of option				$ 0
2014 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining shares available for issuance		1,754,229		1,754,229
2004 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining shares available for issuance		203,165		203,165
Additional shares authorized for issuance	100,000
Plan participants purchased shares				31,624
Average purchase price under 2004 Employee Stock Purchase Plan		$ 0.25		$ 0.25
Cash proceeds				$ 7,000

Stock Based Compensation - St30

Stock Based Compensation - Stock Option Activity Under Equity Incentive Plan (Detail)	6 Months Ended
	Jun. 30, 2017USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Outstanding, Beginning Balance | shares	10,941,745
Number of Shares, Granted | shares	0
Number of Shares, Exercised | shares	0
Number of Shares, Forfeitures | shares	(209,485)
Number of Shares, Outstanding, Ending Balance | shares	10,732,260
Number of Shares, Vested and expected to vest | shares	10,689,426
Number of Shares, Exercisable | shares	8,640,234
Weighted-Average Exercise Price, Outstanding, Beginning Balance | $ / shares	$ 3
Weighted-Average Exercise Price, Granted | $ / shares	0
Weighted-Average Exercise Price, Exercised | $ / shares	0
Weighted-Average Exercise Price, Forfeitures | $ / shares	1.37
Weighted-Average Exercise Price, Outstanding, Ending Balance | $ / shares	3.03
Weighted-Average Exercise Price, Vested and expected to vest | $ / shares	3.04
Weighted-Average Exercise Price, Exercisable | $ / shares	$ 3.38
Weighted-Average Remaining Contractual Term, Outstanding	4 years 10 months 28 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	4 years 10 months 21 days
Weighted-Average Remaining Contractual Term, Exercisable	4 years 26 days
Aggregate Intrinsic Value, Outstanding | $	$ 2,730
Aggregate Intrinsic Value, Vested and expected to vest | $	2,730
Aggregate Intrinsic Value, Exercisable | $	$ 2,730

Marketable Securities and Fai31

Marketable Securities and Fair Value - Financial Assets at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	$ 14,402	$ 23,217
Basis of Fair Value Measurements, Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	14,103	2,746
Basis of Fair Value Measurements, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	299	20,471
Basis of Fair Value Measurements, Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0	0
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	14,103	2,746
Money Market Funds | Basis of Fair Value Measurements, Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	14,103	2,746
Money Market Funds | Basis of Fair Value Measurements, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0	0
Money Market Funds | Basis of Fair Value Measurements, Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0	0
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities		4,206
Corporate Debt Securities | Basis of Fair Value Measurements, Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities		0
Corporate Debt Securities | Basis of Fair Value Measurements, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities		4,206
Corporate Debt Securities | Basis of Fair Value Measurements, Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities		0
Government Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities		5,299
Government Securities | Basis of Fair Value Measurements, Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities		0
Government Securities | Basis of Fair Value Measurements, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities		5,299
Government Securities | Basis of Fair Value Measurements, Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities		0
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	299	10,966
Commercial Paper | Basis of Fair Value Measurements, Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0	0
Commercial Paper | Basis of Fair Value Measurements, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	299	10,966
Commercial Paper | Basis of Fair Value Measurements, Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	$ 0	$ 0

Marketable Securities and Fai32

Marketable Securities and Fair Value - Summary of Company's Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]
Cost Basis	$ 299	$ 13,002
Unrealized Gain	0	1
Unrealized Loss	0	(3)
Fair Value	299	13,000
Money Market Funds
Schedule Of Available For Sale Securities [Line Items]
Cost Basis	14,103	2,746
Unrealized Gain	0	0
Unrealized Loss	0	0
Fair Value	14,103	2,746
Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Cost Basis		4,208
Unrealized Gain		0
Unrealized Loss		(2)
Fair Value		4,206
U.S. Government Securities
Schedule Of Available For Sale Securities [Line Items]
Cost Basis		5,299
Unrealized Gain		1
Unrealized Loss		(1)
Fair Value		5,299
Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Cost Basis	299	10,966
Unrealized Gain	0	0
Unrealized Loss	0	0
Fair Value	299	10,966
Marketable Securities Including Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Cost Basis	14,402	23,219
Unrealized Gain	0	1
Unrealized Loss	0	(3)
Fair Value	14,402	23,217
Less Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Cost Basis	14,103	10,217
Unrealized Gain	0	0
Unrealized Loss	0	0
Fair Value	$ 14,103	$ 10,217

Marketable Securities and Fai33

Marketable Securities and Fair Value - Additional Information (Detail) - USD ($) shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Schedule Of Available For Sale Securities [Line Items]
Realized gain or losses	$ 0	$ 0	$ 0	$ 0
Weighted average maturity for available for sale securities			1 month
Marketable securities with unrealized loss positions	$ 0		$ 0
Shares of common stock to be purchased with warrants	8.3		8.3
Maximum
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, longest maturity date			2017-07