Molecular Templates (MTEM) 10-Q 1 Aug 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2014	Jul. 25, 2014
Document And Entity Information [Line Items]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
Trading Symbol	'THLD	'
Entity Registrant Name	'THRESHOLD PHARMACEUTICALS INC	'
Entity Central Index Key	'0001183765	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	59,366,054

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$6,463	$7,279
Marketable securities, current	56,571	58,390
Collaboration receivable	4,263	18,094
Prepaid expenses and other current assets	2,845	2,246
Total current assets	70,142	86,009
Marketable securities, non-current	12,181	16,364
Property and equipment, net	690	686
Other assets	1,159	1,059
Total assets	84,172	104,118
Current liabilities:	'	'
Accounts payable	2,891	1,689
Accrued clinical and development expenses	7,173	7,444
Accrued liabilities	2,511	3,161
Deferred revenue, current	14,722	14,722
Total current liabilities	27,297	27,016
Warrant liability	15,299	23,421
Deferred revenue, non-current	69,555	76,916
Deferred rent	274	240
Total liabilities	112,425	127,593
Commitments and contingencies (Note 7)	'	'
Stockholders’ equity (deficit):	'	'
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: 59,365,233 shares at June 30, 2014 and 59,232,611 shares at December 31, 2013	59	59
Additional paid-in capital	331,224	328,116
Accumulated other comprehensive gain (loss)	17	28
Accumulated deficit	-359,553	-351,678
Total stockholders’ equity (deficit)	-28,253	-23,475
Total liabilities and stockholders’ equity (deficit)	$84,172	$104,118

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Preferred stock, par value	$0.00	$0.00
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	$0.00	$0.00
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	59,365,233	59,232,611
Common stock, shares outstanding	59,365,233	59,232,611

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations and Comprehensive Loss (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenue	$3,680	$3,180	$7,361	$6,102
Operating expenses:	'	'	'	'
Research and development	8,664	7,983	18,317	14,451
General and administrative	2,477	2,166	5,111	4,681
Total operating expenses	11,141	10,149	23,428	19,132
Loss from operations	-7,461	-6,969	-16,067	-13,030
Interest income (expense), net	30	34	70	70
Other income (expense), net	6,665	-5,822	8,122	-8,938
Loss before provision for income taxes	-766	-12,757	-7,875	-21,898
Provision for income taxes	'	31	'	104
Net loss	-766	-12,788	-7,875	-22,002
Other comprehensive income (loss):	'	'	'	'
Unrealized gain (loss) on available-for-sale securities	4	-33	-11	-38
Comprehensive loss	($762)	($12,821)	($7,886)	($22,040)
Net loss per common share:	'	'	'	'
Basic	($0.01)	($0.22)	($0.13)	($0.39)
Diluted	($0.12)	($0.22)	($0.25)	($0.39)
Weighted average number of shares used in per common share calculations:	'	'	'	'
Basic	59,347	57,037	59,325	56,763
Diluted	62,998	57,037	63,433	56,763

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Cash Flows (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities:	'	'
Net loss	($7,875)	($22,002)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:	'	'
Depreciation and amortization	726	664
Stock-based compensation expense	2,734	2,325
Change in common stock warrant value	-8,122	8,938
Changes in operating assets and liabilities:	'	'
Collaboration receivable	13,831	13,087
Prepaid expenses and other assets	-699	-746
Accounts payable	1,202	-24
Accrued clinical and development expenses	-271	1,269
Accrued liabilities	-650	-216
Deferred rent	34	-11
Deferred revenue	-7,361	23,898
Net cash (used in) provided by operating activities	-6,451	27,182
Cash flows from investing activities:	'	'
Acquisition of property and equipment	-171	-97
Acquisition of marketable securities	-33,137	-74,904
Proceeds from sale of marketable securities	8,214	1,000
Proceeds from maturities of marketable securities	30,355	39,358
Net cash provided by (used in) investing activities	5,261	-34,643
Cash flows from financing activities:	'	'
Proceeds from issuance of common stock and warrants, net of offering expenses	374	845
Net cash provided by financing activities	374	845
Net increase (decrease) in cash and cash equivalents	-816	-6,616
Cash and cash equivalents, beginning of period	7,279	11,029
Cash and cash equivalents, end of period	$6,463	$4,413

Organization_and_Summary_of_Si

Organization and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2014
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.
	Basis of Presentation
	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America 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 of normal recurring adjustments necessary for the fair statement 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. The condensed consolidated balance sheet at December 31, 2013 has been derived from the audited financial statements at that date but does not include all the information and footnotes required by accounting principles generally accepted in the United States of America. 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, 2013 included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (“SEC”) on March 6, 2014.
	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.
	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 are related to its collaboration arrangement with Merck KGaA, which was entered in February 2012. The collaboration with Merck KGaA provides for various types of payments to the Company, including non-refundable upfront license, milestone and royalty payments. The Company recognizes 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. The Company also receives reimbursement for Merck KGaA’s 70% share for eligible worldwide development expenses for TH-302. Such reimbursement is reflected as a reduction of operating expenses.
	For multiple-element arrangements, each deliverable within a multiple deliverable revenue arrangement is accounted for as a separate unit of accounting if both of the following criteria are met: (1) the delivered item or items have value to the customer on a standalone basis and (2) for an arrangement that includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in the Company’s control. The deliverables under the Merck KGaA agreement have been determined to be a single unit of accounting and as such the revenue relating to this unit of accounting will be recorded as deferred revenue and recognized ratably over the term of its estimated performance period under the agreement, which is the product development period. The Company determines the estimated performance period and it will be periodically reviewed based on the progress of the related product development plan. The effect of a change made to an estimated performance period, and the related ratably recognized revenue, would occur on a prospective basis in the period that the change was made.
	Deferred revenue associated with a non-refundable payment received under a collaborative agreement for which the performance obligations are terminated will result in an immediate recognition of any remaining deferred revenue in the period that termination occurred provided that all performance obligations have been satisfied.
	The Company recognizes revenue from milestone payments when: (i) the milestone event is substantive and its achievability has substantive uncertainty at the inception of the agreement, and (ii) the Company does not have ongoing performance obligations related to the achievement of the milestone earned. Milestone payments are considered substantive if all of the following conditions are met: the milestone payment (a) is commensurate with either the Company’s performance subsequent to the inception of the arrangement to achieve the milestone or the enhancement of the value of the delivered item or items as a result of a specific outcome resulting from the Company’s performance subsequent to the inception of the arrangement to achieve the milestone, (b) relates solely to past performance, and (c) is reasonable relative to all of the deliverables and payment terms (including other potential milestone consideration) within the arrangements. See Note 3, “Collaboration Arrangements,” for analysis of milestone events deemed to be substantive or non-substantive.

Net_Loss_Per_Common_Share

Net Loss Per Common Share	6 Months Ended
	Jun. 30, 2014
Net Loss Per Common Share	'
	NOTE 2 — NET LOSS PER COMMON SHARE
	Basic net loss per common share is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. Diluted net loss per common 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						Six Months Ended
		June 30,						June 30,
		2014			2013			2014			2013
	Numerator:
	Net loss - basic	$	(766	)	$	(12,788	)	$	(7,875	)	$	(22,002	)
	Less: noncash income from change in fair		(6,665	)		—			(8,122	)		—
	value of common stock warrants
	Net loss - diluted		(7,431	)		(12,788	)		(15,997	)		(22,002	)
	Denominator:
	Weighted average common shares outstanding		59,347			57,037			59,325			56,763
	Dilutive effect of warrants		3,651			—			4,108			—
	Weighted-average common shares outstanding		62,998			57,037			63,433			56,763
	and dilutive potential common shares —
	diluted
	Net income (loss) per share
	Basic	$	(0.01	)	$	(0.22	)	$	(0.13	)	$	(0.39	)
	Diluted	$	(0.12	)	$	(0.22	)	$	(0.25	)	$	(0.39	)
	The following outstanding warrants, options and purchase rights under the Company’s 2004 Employee Stock 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						Six Months Ended
		June 30,						June 30,
		2014			2013			2014			2013
	Shares issuable upon exercise of warrants		—			9,634			—			9,634
	Shares issuable upon exercise of stock options		8,161			6,570			8,161			6,570
	Shares issuable related to the ESPP		71			85			71			85

Collaboration_Arrangements

Collaboration Arrangements	6 Months Ended
	Jun. 30, 2014
Collaboration Arrangements	'
	NOTE 3 — COLLABORATION ARRANGEMENTS
	On February 3, 2012, the Company entered into a global license and co-development agreement with Merck KGaA, Darmstadt, Germany, to co-develop and commercialize TH-302, the Company’s small molecule hypoxia-targeted drug. Under the terms of the agreement, Merck KGaA received co-development rights, exclusive global commercialization rights and provided the Company with an option to co-commercialize TH-302 in the United States. To date, the Company has received $110 million in upfront and milestone payments, including $12.5 million received during the quarter ended March 31, 2014. The milestones earned to date were not deemed to be substantive milestones because the work related to the achievement of these items was predominately completed prior to the inception of the arrangement or was not commensurate with Company’s performance subsequent to the inception of the arrangement to achieve the milestone. The Company is eligible to earn additional potential milestone payments of up to $100 million in regulatory and development milestones, and $340 million in commercialization milestones.
	In the United States, the Company has primary responsibility for development of TH-302 in the soft tissue sarcoma indication. The Company and Merck KGaA will jointly develop TH-302 in all other cancer indications being pursued. Merck KGaA will pay 70% of worldwide development expenses for TH-302. Subject to FDA approval in the United States, Merck KGaA will initially be responsible for commercialization of TH-302 with the Company receiving a tiered, double-digit royalty on sales. Under the royalty bearing portion of the agreement, Threshold retains the option to co-promote TH-302 in the United States. Additionally, the Company retains the option to co-commercialize TH-302 in the United States, upon the achievement of certain sales and regulatory milestones, allowing the Company to participate in up to 50% of the profits in the United States depending on total sales. Outside of the United States, Merck KGaA will be solely responsible for the commercialization of TH-302 with the Company receiving a tiered, double digit royalty on sales in these territories. The agreement will continue on a country-by-country and product-by-product basis until the later of the last to expire patent covering such product containing TH-302 in such country or ten years following the commercial launch of a product containing TH-302 in such country, unless terminated earlier. Merck KGaA has the right to terminate the agreement on limited notice to the Company, and each party has the right to terminate the agreement following an uncured material breach by the other party.
	The Company’s deliverables under the Merck KGaA agreement, which include delivery of the rights and license for TH-302 and performance of research and development activities, have been determined to be a single unit of accounting. The delivered license does not have standalone value at the inception of the arrangement due to the Company’s proprietary expertise with respect to the licensed compound and related ongoing developmental participation under the global license and co-development agreement, which is required for Merck KGaA to fully realize the value from the delivered license. Therefore, the revenue relating to this unit of accounting will be recorded as deferred revenue and recognized over the estimated performance period under the agreement, which is the product development period. The Company has recorded $110 million of the upfront payment and milestones payments as deferred revenue and is amortizing them ratably over its estimated period of performance, which the Company currently estimates to end on March 31, 2020. As a result, the Company recognized $3.7 million and $7.4 million of revenue during the three and six months ended June 30, 2014, respectively, compared to $3.2 and $6.1 million for the three and six months ended June 30, 2013, respectively. The Company will periodically review and, if necessary, revise the estimated periods of performance of its collaboration. The Company also earned $3.5 million and $9.4 million reimbursement for eligible worldwide development expenses for TH-302 from Merck KGaA during the three and six months ended June 30, 2014, respectively compared to $2.5 million and $6.1 million for the three and six months ended June 30, 2013, respectively. Such earned reimbursement has been reflected as a reduction of operating expenses.
	Of the remaining potential future milestones, $100 million are related to regulatory and development milestones and $340 million are related to commercialization milestones that may be received under the Merck KGaA Agreement. Regulatory milestones include the filing and acceptance of regulatory applications for marketing approval in major markets. Development milestones include primarily the initiation of various phases of clinical trials. Commercialization milestones include the achievement of first commercial sales in a particular market or annual product sales in excess of a pre-specified threshold. At the inception of the collaboration agreement the Company assessed regulatory and development milestones to be substantive where there was substantive scientific and regulatory uncertainty of achievement, the amounts of payments assigned were considered to be commensurate with the enhancement that occurred subsequent to inception of the Merck KGaA agreement, of the value of the delivered rights and license of TH-302 and the Company’s performance is necessary to the achievement of the milestone. Accordingly, the Company will recognize payments related to the achievement of such milestones, if any, when such milestone is achieved. Regulatory and development milestones that do not meet these conditions were considered non-substantive and payments related to the achievement of such milestones, if any, will be recorded as deferred revenue and amortized ratably over the estimated period of performance. Final determination of whether a development or regulatory milestone is substantive will depend upon the Company’s role in achieving the milestone. The specific role and responsibilities related to the regulatory and development activities for certain of these milestones have yet to be determined and may change during the development period. Under the Merck KGaA agreement, Merck KGaA will initially be responsible for commercialization activities and the Company initially may not be involved in the achievement of these commercialization milestones. These commercialization milestones would typically be achieved after the completion of the Company’s regulatory and development activities. If there are no future development obligations, the Company expects to account for the commercialization milestones in the same manner as royalties, with revenue recognized upon achievement of the milestone.

Stockholders_Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2014
Stockholders' Equity	'
	NOTE 4 — STOCKHOLDERS’ EQUITY
	Common Stock Warrants
	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 required 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, 2014 and December 31, 2013, the Company had warrants outstanding to purchase 4,287,940 shares of common stock, having an exercise price of $2.05 per share, which warrants were initially issued by the Company in a private placement in October 2009. The fair value of these warrants on June 30, 2014 and December 31, 2013 was determined using a Black Scholes valuation model with the following level 3 inputs:
		June 30,			December 31,
		2014			2013
	Risk-free interest rate		0.11	%		0.13	%
	Expected life (in years)		0.27			0.76
	Dividend yield		—			—
	Volatility		44	%		49	%
	Stock price	$	3.96		$	4.67
	During the three and six months ended June 30, 2014, the change in fair value of $3.4 million and $3.1 million, respectively, related to the October 2009 warrants was recorded as other income in the Company’s consolidated statement of operations.
	At both June 30, 2014 and December 31, 2013, the Company had also warrants outstanding to purchase 3,993,783 shares of common stock, having an exercise price of $2.46 per share, which warrants were initially issued by the Company in an underwritten public offering in March 2011. The fair value of these warrants on June 30, 2014 and December 31, 2013 was determined using a Black Scholes valuation model with the following level 3 inputs:
		June 30,			December 31,
		2014			2013
	Risk-free interest rate		0.47	%		0.78	%
	Expected life (in years)		1.71			2.21
	Dividend yield		—			—
	Volatility		50	%		88	%
	Stock price	$	3.96		$	4.67
	During the three and six months ended June 30, 2014, the change in fair value of $3.2 million and $5.0 million, respectively, related to the March 2011 warrants was recorded as other income in the Company’s consolidated statement of operations.
	The following table sets forth the Company’s financial liabilities, related to warrants issued in the October 2009 and March 2011 offerings, subject to fair value measurements as of June 30, 2014 and December 31, 2013:
		Fair Value as of			Basis of Fair Value Measurements
		June 30,
		2014
	(in thousands)				Level 1			Level 2		Level 3
	October 2009 warrants	$	8,190		$	—		$	—	$	8,190
	March 2011 warrants		7,109			—			—		7,109
	Total common stock warrants	$	15,299		$	—		$	—	$	15,299
		Fair Value as of			Basis of Fair Value Measurements
		December 31,
		2013
	(in thousands)				Level 1			Level 2		Level 3
	October 2009 warrants	$	11,320		$	—		$	—	$	11,320
	March 2011 warrants		12,101			—			—		12,101
	Total common stock warrants	$	23,421		$	—		$	—	$	23,421
	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, 2013	$	23,421
	Change in fair value of common stock warrants during six months ended June 30, 2014		(8,122	)
	Exercise of warrants during six months ended June 30, 2014		—
	Balance at June 30, 2014	$	15,299

Stock_Based_Compensation

Stock Based Compensation	6 Months Ended
	Jun. 30, 2014
Stock Based Compensation	'
	NOTE 5 — 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 Company’s ESPP, and the value of options issued to non-employees for services rendered, was allocated to research and development and general and administrative in the unaudited consolidated statements of operations for the three and six months ended June 30, 2014 and 2013 as follows (in thousands):
		Three Months Ended							Six Months Ended
		June 30,							June 30,
		2014				2013			2014			2013
	Amortization of stock-based compensation:
	Research and development	$	846			$	663		$	1,517		$	1,197
	General and administrative		622				609			1,217			1,128
		$	1,468			$	1,272		$	2,734		$	2,325
	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 Company’s ESPP was estimated using the following weighted-average assumptions for the three and six months ended June 30, 2014 and 2013:
		Three Months Ended							Six Months Ended
		June 30,							June 30,
		2014				2013			2014			2013
	Employee Stock Options:
	Risk-free interest rate		1.81	%			0.96	%		1.82	%		1.13	%
	Expected term (in years)		5.97				5.47			5.97			5.97
	Dividend yield		—				—			—			—
	Volatility		94	%			102	%		94	%		101	%
	Weighted-average fair value of stock options granted	$	2.79			$	4.28		$	2.89		$	4.03
		Three Months Ended							Six Months Ended
		June 30,							June 30,
		2014				2013			2014			2013
	Employee Stock Purchase Plan (ESPP):
	Risk-free interest rate		0.18	%			0.2	%		0.18	%		0.2	%
	Expected term (in years)		1.23				1.25			1.23			1.25
	Dividend yield		—				—			—			—
	Volatility		53	%			92	%		53	%		92	%
	Weighted-average fair value of ESPP purchase rights	$	1.79			$	2.44		$	1.79		$	2.44
	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” (“SAB 107”). To determine the risk-free interest rate, the Company utilized an average interest rate based on U.S. Treasury instruments with a term consistent with the expected term of the Company’s stock based awards. To determine the expected stock price volatility for the Company’s stock based awards, the Company utilized the historical volatilities of the Company. The fair value of all the Company’s stock based awards assumes no dividends as the Company does not anticipate paying cash dividends on its common stock.
	Employee Stock-based Compensation Expense
	As required by ASC 718, the Company recognized $1.5 million and $2.7 million of stock-based compensation expense related to stock options and purchase rights, under the Company’s equity incentive plans and ESPP, for the three and six months ended June 30, 2014, respectively, and $1.2 million and $2.2 million of stock-based compensation for the three and six months ended June 30, 2013, respectively. As of June 30, 2014, the total unrecognized compensation cost related to unvested stock-based awards granted to employees under the Company’s equity incentive plans was approximately $12.7 million before forfeitures. This cost will be recorded as compensation expense on a straight-line basis over the remaining weighted average requisite service period of approximately 2.7 years.
	Non-employee Stock-based Compensation Expense
	The Company accounts for equity instruments issued to non-employees in accordance with ASC 505, “Equity.” The equity instruments consisting of stock options are valued using the Black-Scholes option pricing model. The values attributable to these options are amortized over the service period and the unvested portion of these options is remeasured at each vesting date. In connection with the grant of stock options to non-employees, the Company recorded stock-based compensation of approximately $19,000 and $55,000 for the three and six months ended June 30, 2014, respectively, and $34,000 and $0.1 million for the three and six months ended June 30, 2013, respectively.
	Equity Incentive Plans
	Equity Incentive Plans On January 1, 2014, an additional 1,250,000 shares was authorized for issuance under the 2004 Equity Incentive Plan (“2004 Incentive Plan”), pursuant to the annual automatic increase to the authorized shares under the 2004 Incentive Plan.
	The 2004 Incentive Plan expired pursuant to its terms on April 7, 2014. No additional awards have been or will be made after April 7, 2014 under the 2004 Incentive Plan. In May 2014, the Company adopted the 2014 Equity Incentive Plan (“2014 Plan”). The terms of the 2014 Plan provide for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, other stock awards, and performance awards that may be settled in cash, stock, or other property. The total number of shares of the Company’s common stock reserved for issuance under the 2014 Plan is equal to the sum of (i) 6,000,000 newly reserved shares plus (ii) up to 6,626,157 additional shares (the “Prior Plan Shares”) that may be added to the 2014 Plan in connection with the forfeiture or expiration of awards outstanding under the 2004 Incentive Plan as of May 15, 2014 (the “Returning Shares”). The Prior Plan Shares will be added to the share reserve under the 2014 Plan only as and when such shares become Returning Shares. At June 30, 2014, 4,446,294 shares were authorized and available for issuance under the 2014 Plan.
	The following table summarizes stock option activity under the Company’s equity incentive plans:
	Options		Number of				Weighted-			Weighted-			Aggregate
			Shares				Average			Average			Intrinsic
							Exercise			Remaining			Value
							Price			Contractual
										Term
	Outstanding at December 31, 2013			6,526,506			$	3.66			—			—
	Granted			1,765,250			$	3.79			—			—
	Exercised			(58,560	)		$	1.45			—			—
	Forfeitures			(72,333	)		$	4.62			—			—
	Outstanding at June 30, 2014			8,160,863			$	3.69			7.67			8,434,466
	Vested and expected to vest June 30, 2014			8,071,025			$	3.69			7.65			8,412,349
	Exercisable at June 30, 2014			4,450,857			$	3.04			6.6			7,212,989
	The total intrinsic value of stock options exercised during the six months ended June 30, 2014 and 2013 were $0.2 million and $0.4 million, respectively, as determined at the date of the option exercise. Cash received from stock option exercises was $0.1 million and $0.2 million for each of the six months ended June 30, 2014 and 2013, respectively. The Company issues new shares of common stock upon exercise of options. In connection with these exercises, there was no tax benefit realized by the Company due to the Company’s current loss position.
	2004 Employee Stock Purchase Plan On January 1, 2014, an additional 100,000 shares was authorized for issuance under the 2004 Employee Stock Purchase Plan (“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, 2014, plan participants had purchased 74,062 shares at an average purchase price of $3.91 for total cash proceeds of $0.3 million. At June 30, 2014, 261,834 shares were authorized and available for issuance under the ESPP.

Fair_Value_Measurements_and_Ma

Fair Value Measurements and Marketable Securities	6 Months Ended
	Jun. 30, 2014
Fair Value Measurements and Marketable Securities	'
	NOTE 6 — FAIR VALUE MEASUREMENTS AND MARKETABLE SECURITIES
	The Company accounts for its marketable securities in accordance with ASC 820 “Fair Value Measurements and Disclosures.” ASC 820 defines fair value, establishes a framework for measuring fair value in GAAP, and expands disclosures about fair value measurements. ASC 820 defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. ASC 820 also establishes a fair value hierarchy which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard describes three levels of inputs that may be used to measure fair value:
	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, 2014 and December 31, 2013:
		Fair Value as of		Basis of Fair Value Measurements
		June 30,
		2014
	(in thousands)			Level 1			Level 2			Level 3
	Money market funds	$	6,463	$	6,463		$	—		$	—
	Certificates of deposit		2,844		—			2,844			—
	Corporate debt securities		40,937		—			40,937			—
	U.S. Government securities		20,023		—			20,023			—
	Municipal securities		1,450		—			1,450			—
	Commercial paper		3,498		—			3,498			—
	Total cash equivalents and marketable securities	$	75,215	$	6,463		$	68,752		$	—
		Fair Value as of		Basis of Fair Value Measurements
		December 31,
		2013
	(in thousands)			Level 1			Level 2			Level 3
	Money market funds	$	4,285	$	4,285		$	—		$	—
	Certificates of deposit		1,584		—			1,584			—
	Corporate debt securities		49,019		—			49,019			—
	U.S. Government securities		21,731		—			21,731			—
	Municipal securities		2,815		—			2,815			—
	Commercial paper		2,599		—			2,599			—
	Total cash equivalents and marketable securities	$	82,033	$	4,285		$	77,748		$	—
	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, 2014 and December 31, 2013:
	As of June 30, 2014 (in thousands):	Cost Basis		Unrealized			Unrealized			Fair
				Gain			Loss			Value
	Money market funds	$	6,463	$	—		$	—		$	6,463
	Certificates of deposit		2,844		—			—			2,844
	Corporate debt securities		40,930		12			(5	)		40,937
	U.S. Government securities		20,013		11			(1	)		20,023
	Municipal securities		1,450		—			—			1,450
	Commercial paper		3,498		—			—			3,498
			75,198		23			(6	)		75,215
	Less cash equivalents		6,463		—			—			6,463
	Total marketable securities	$	68,735	$	23		$	(6	)	$	68,752
	As of December 31, 2013 (in thousands):	Cost Basis		Unrealized			Unrealized			Fair
				Gain			Loss			Value
	Money market funds	$	4,285	$	—		$	—		$	4,285
	Certificates of deposit		1,584		—			—			1,584
	Corporate debt securities		49,001		25			(7	)		49,019
	U.S. Government securities		21,722		12			(3	)		21,731
	Municipal securities		2,814		1			—			2,815
	Commercial paper		2,599		—			—			2,599
			82,005		38			(10	)		82,033
	Less cash equivalents		7,279		—			—			7,279
	Total marketable securities	$	74,726	$	38		$	(10	)	$	74,754
	There were no realized gains or losses in the three and six months ended June 30, 2014 and 2013, respectively.
	As of June 30, 2014, the weighted average maturity for the Company’s available for sale securities was 6.6 months, with the longest maturity being November 2015.
	The following table provides the breakdown of the marketable securities with unrealized losses at June 30, 2014 (in thousands):
		In loss position for less
		than twelve months
	As of June 30, 2014 (in thousands):	Fair		Unrealized
		Value		Loss
	U.S. Government securities	$	8,010	$	(1	)
	Corporate debt securities		12,259		(5	)
	Total marketable securities	$	20,269	$	(6	)
	The Company determined the fair value of the liability associated with its warrants to purchase 8.3 million shares of outstanding common stock using a Black-Scholes Model. See detailed discussion in Note 4 — Stockholders’ Equity.

Commitments_and_Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2014
Commitments and Contingencies	'
	NOTE 7 — COMMITMENTS AND CONTINGENCIES
	The Company leases certain of its facilities under noncancelable leases, which qualify for operating lease accounting treatment under ASC 840, “Leases,” and, as such, these facilities are not included on its unaudited condensed consolidated balance sheets. The future rental payments required by the Company for all of its facilities under noncancelable operating leases are as follows (in thousands):
	Years Ending December 31,
	2014	$	447
	2015		918
	2016		953
	2017		238
	Thereafter		—
	Total	$	2,556
	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, 2014.
	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_Si1

Organization and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2014
Basis of Presentation	'
	Basis of Presentation
	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America 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 of normal recurring adjustments necessary for the fair statement 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. The condensed consolidated balance sheet at December 31, 2013 has been derived from the audited financial statements at that date but does not include all the information and footnotes required by accounting principles generally accepted in the United States of America. 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, 2013 included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (“SEC”) on March 6, 2014.
	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.
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 are related to its collaboration arrangement with Merck KGaA, which was entered in February 2012. The collaboration with Merck KGaA provides for various types of payments to the Company, including non-refundable upfront license, milestone and royalty payments. The Company recognizes 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. The Company also receives reimbursement for Merck KGaA’s 70% share for eligible worldwide development expenses for TH-302. Such reimbursement is reflected as a reduction of operating expenses.
	For multiple-element arrangements, each deliverable within a multiple deliverable revenue arrangement is accounted for as a separate unit of accounting if both of the following criteria are met: (1) the delivered item or items have value to the customer on a standalone basis and (2) for an arrangement that includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in the Company’s control. The deliverables under the Merck KGaA agreement have been determined to be a single unit of accounting and as such the revenue relating to this unit of accounting will be recorded as deferred revenue and recognized ratably over the term of its estimated performance period under the agreement, which is the product development period. The Company determines the estimated performance period and it will be periodically reviewed based on the progress of the related product development plan. The effect of a change made to an estimated performance period, and the related ratably recognized revenue, would occur on a prospective basis in the period that the change was made.
	Deferred revenue associated with a non-refundable payment received under a collaborative agreement for which the performance obligations are terminated will result in an immediate recognition of any remaining deferred revenue in the period that termination occurred provided that all performance obligations have been satisfied.
	The Company recognizes revenue from milestone payments when: (i) the milestone event is substantive and its achievability has substantive uncertainty at the inception of the agreement, and (ii) the Company does not have ongoing performance obligations related to the achievement of the milestone earned. Milestone payments are considered substantive if all of the following conditions are met: the milestone payment (a) is commensurate with either the Company’s performance subsequent to the inception of the arrangement to achieve the milestone or the enhancement of the value of the delivered item or items as a result of a specific outcome resulting from the Company’s performance subsequent to the inception of the arrangement to achieve the milestone, (b) relates solely to past performance, and (c) is reasonable relative to all of the deliverables and payment terms (including other potential milestone consideration) within the arrangements. See Note 3, “Collaboration Arrangements,” for analysis of milestone events deemed to be substantive or non-substantive.

Net_Loss_Per_Common_Share_Tabl

Net Loss Per Common Share (Tables)	6 Months Ended
	Jun. 30, 2014
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						Six Months Ended
		June 30,						June 30,
		2014			2013			2014			2013
	Numerator:
	Net loss - basic	$	(766	)	$	(12,788	)	$	(7,875	)	$	(22,002	)
	Less: noncash income from change in fair		(6,665	)		—			(8,122	)		—
	value of common stock warrants
	Net loss - diluted		(7,431	)		(12,788	)		(15,997	)		(22,002	)
	Denominator:
	Weighted average common shares outstanding		59,347			57,037			59,325			56,763
	Dilutive effect of warrants		3,651			—			4,108			—
	Weighted-average common shares outstanding		62,998			57,037			63,433			56,763
	and dilutive potential common shares —
	diluted
	Net income (loss) per share
	Basic	$	(0.01	)	$	(0.22	)	$	(0.13	)	$	(0.39	)
	Diluted	$	(0.12	)	$	(0.22	)	$	(0.25	)	$	(0.39	)
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 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						Six Months Ended
		June 30,						June 30,
		2014			2013			2014			2013
	Shares issuable upon exercise of warrants		—			9,634			—			9,634
	Shares issuable upon exercise of stock options		8,161			6,570			8,161			6,570
	Shares issuable related to the ESPP		71			85			71			85

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2014
Financial Liabilities Subject to Fair Value Measurements	'
	The following table sets forth the Company’s financial liabilities, related to warrants issued in the October 2009 and March 2011 offerings, subject to fair value measurements as of June 30, 2014 and December 31, 2013:
		Fair Value as of			Basis of Fair Value Measurements
		June 30,
		2014
	(in thousands)				Level 1			Level 2		Level 3
	October 2009 warrants	$	8,190		$	—		$	—	$	8,190
	March 2011 warrants		7,109			—			—		7,109
	Total common stock warrants	$	15,299		$	—		$	—	$	15,299
		Fair Value as of			Basis of Fair Value Measurements
		December 31,
		2013
	(in thousands)				Level 1			Level 2		Level 3
	October 2009 warrants	$	11,320		$	—		$	—	$	11,320
	March 2011 warrants		12,101			—			—		12,101
	Total common stock warrants	$	23,421		$	—		$	—	$	23,421
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, 2013	$	23,421
	Change in fair value of common stock warrants during six months ended June 30, 2014		(8,122	)
	Exercise of warrants during six months ended June 30, 2014		—
	Balance at June 30, 2014	$	15,299
October 2009 Offering	'
Outstanding Warrants Valuation Assumption	'
	The fair value of these warrants on June 30, 2014 and December 31, 2013 was determined using a Black Scholes valuation model with the following level 3 inputs:
		June 30,			December 31,
		2014			2013
	Risk-free interest rate		0.11	%		0.13	%
	Expected life (in years)		0.27			0.76
	Dividend yield		—			—
	Volatility		44	%		49	%
	Stock price	$	3.96		$	4.67
March 2011 Offering	'
Outstanding Warrants Valuation Assumption	'
	The fair value of these warrants on June 30, 2014 and December 31, 2013 was determined using a Black Scholes valuation model with the following level 3 inputs:
		June 30,			December 31,
		2014			2013
	Risk-free interest rate		0.47	%		0.78	%
	Expected life (in years)		1.71			2.21
	Dividend yield		—			—
	Volatility		50	%		88	%
	Stock price	$	3.96		$	4.67

Stock_Based_Compensation_Table

Stock Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2014
Stock-Based Compensation Expense	'
	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 Company’s ESPP, and the value of options issued to non-employees for services rendered, was allocated to research and development and general and administrative in the unaudited consolidated statements of operations for the three and six months ended June 30, 2014 and 2013 as follows (in thousands):
		Three Months Ended							Six Months Ended
		June 30,							June 30,
		2014				2013			2014			2013
	Amortization of stock-based compensation:
	Research and development	$	846			$	663		$	1,517		$	1,197
	General and administrative		622				609			1,217			1,128
		$	1,468			$	1,272		$	2,734		$	2,325
Weighted-Average Fair Value Valuation Assumptions	'
	The fair value of employee stock options and employee purchase rights under the Company’s ESPP was estimated using the following weighted-average assumptions for the three and six months ended June 30, 2014 and 2013:
		Three Months Ended							Six Months Ended
		June 30,							June 30,
		2014				2013			2014			2013
	Employee Stock Options:
	Risk-free interest rate		1.81	%			0.96	%		1.82	%		1.13	%
	Expected term (in years)		5.97				5.47			5.97			5.97
	Dividend yield		—				—			—			—
	Volatility		94	%			102	%		94	%		101	%
	Weighted-average fair value of stock options granted	$	2.79			$	4.28		$	2.89		$	4.03
		Three Months Ended							Six Months Ended
		June 30,							June 30,
		2014				2013			2014			2013
	Employee Stock Purchase Plan (ESPP):
	Risk-free interest rate		0.18	%			0.2	%		0.18	%		0.2	%
	Expected term (in years)		1.23				1.25			1.23			1.25
	Dividend yield		—				—			—			—
	Volatility		53	%			92	%		53	%		92	%
	Weighted-average fair value of ESPP purchase rights	$	1.79			$	2.44		$	1.79		$	2.44
Stock Option Activity Under Equity Incentive Plan	'
	The following table summarizes stock option activity under the Company’s equity incentive plans:
	Options		Number of				Weighted-			Weighted-			Aggregate
			Shares				Average			Average			Intrinsic
							Exercise			Remaining			Value
							Price			Contractual
										Term
	Outstanding at December 31, 2013			6,526,506			$	3.66			—			—
	Granted			1,765,250			$	3.79			—			—
	Exercised			(58,560	)		$	1.45			—			—
	Forfeitures			(72,333	)		$	4.62			—			—
	Outstanding at June 30, 2014			8,160,863			$	3.69			7.67			8,434,466
	Vested and expected to vest June 30, 2014			8,071,025			$	3.69			7.65			8,412,349
	Exercisable at June 30, 2014			4,450,857			$	3.04			6.6			7,212,989

Fair_Value_Measurements_and_Ma1

Fair Value Measurements and Marketable Securities (Tables)	6 Months Ended
	Jun. 30, 2014
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, 2014 and December 31, 2013:
		Fair Value as of		Basis of Fair Value Measurements
		June 30,
		2014
	(in thousands)			Level 1			Level 2			Level 3
	Money market funds	$	6,463	$	6,463		$	—		$	—
	Certificates of deposit		2,844		—			2,844			—
	Corporate debt securities		40,937		—			40,937			—
	U.S. Government securities		20,023		—			20,023			—
	Municipal securities		1,450		—			1,450			—
	Commercial paper		3,498		—			3,498			—
	Total cash equivalents and marketable securities	$	75,215	$	6,463		$	68,752		$	—
		Fair Value as of		Basis of Fair Value Measurements
		December 31,
		2013
	(in thousands)			Level 1			Level 2			Level 3
	Money market funds	$	4,285	$	4,285		$	—		$	—
	Certificates of deposit		1,584		—			1,584			—
	Corporate debt securities		49,019		—			49,019			—
	U.S. Government securities		21,731		—			21,731			—
	Municipal securities		2,815		—			2,815			—
	Commercial paper		2,599		—			2,599			—
	Total cash equivalents and marketable securities	$	82,033	$	4,285		$	77,748		$	—
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, 2014 and December 31, 2013:
	As of June 30, 2014 (in thousands):	Cost Basis		Unrealized			Unrealized			Fair
				Gain			Loss			Value
	Money market funds	$	6,463	$	—		$	—		$	6,463
	Certificates of deposit		2,844		—			—			2,844
	Corporate debt securities		40,930		12			(5	)		40,937
	U.S. Government securities		20,013		11			(1	)		20,023
	Municipal securities		1,450		—			—			1,450
	Commercial paper		3,498		—			—			3,498
			75,198		23			(6	)		75,215
	Less cash equivalents		6,463		—			—			6,463
	Total marketable securities	$	68,735	$	23		$	(6	)	$	68,752
	As of December 31, 2013 (in thousands):	Cost Basis		Unrealized			Unrealized			Fair
				Gain			Loss			Value
	Money market funds	$	4,285	$	—		$	—		$	4,285
	Certificates of deposit		1,584		—			—			1,584
	Corporate debt securities		49,001		25			(7	)		49,019
	U.S. Government securities		21,722		12			(3	)		21,731
	Municipal securities		2,814		1			—			2,815
	Commercial paper		2,599		—			—			2,599
			82,005		38			(10	)		82,033
	Less cash equivalents		7,279		—			—			7,279
	Total marketable securities	$	74,726	$	38		$	(10	)	$	74,754
Marketable Securities with Unrealized Losses	'
	The following table provides the breakdown of the marketable securities with unrealized losses at June 30, 2014 (in thousands):
		In loss position for less
		than twelve months
	As of June 30, 2014 (in thousands):	Fair		Unrealized
		Value		Loss
	U.S. Government securities	$	8,010	$	(1	)
	Corporate debt securities		12,259		(5	)
	Total marketable securities	$	20,269	$	(6	)

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2014
Future Rental Payments under Noncancelable Operating Leases	'
	The future rental payments required by the Company for all of its facilities under noncancelable operating leases are as follows (in thousands):
	Years Ending December 31,
	2014	$	447
	2015		918
	2016		953
	2017		238
	Thereafter		—
	Total	$	2,556

Organization_and_Summary_of_Si2

Organization and Summary of Significant Accounting Policies - Additional Information (Detail) (Merck KGaA)	6 Months Ended
	Jun. 30, 2014
Merck KGaA	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'
Percentage share of eligible worldwide development expenses	70.00%

Net_Loss_Per_Common_Share_Reco

Net Loss Per Common Share - Reconciliation of Numerator and Denominator (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Numerator:	'	'	'	'
Net loss - basic	($766)	($12,788)	($7,875)	($22,002)
Less: noncash income from change in fair value of common stock warrants	-6,665	'	-8,122	'
Net loss - diluted	($7,431)	($12,788)	($15,997)	($22,002)
Denominator:	'	'	'	'
Weighted average common shares outstanding	59,347	57,037	59,325	56,763
Dilutive effect of warrants	3,651	'	4,108	'
Weighted-average common shares outstanding and dilutive potential common shares — diluted	62,998	57,037	63,433	56,763
Net income (loss) per share	'	'	'	'
Basic	($0.01)	($0.22)	($0.13)	($0.39)
Diluted	($0.12)	($0.22)	($0.25)	($0.39)

Net_Loss_Per_Common_Share_Warr

Net Loss Per Common Share - Warrants, Options and Purchase Rights Excluded from Computation of Diluted Net Loss Per Share (Detail)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Warrants	'	'	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'	'	'
Shares issuable	'	9,634	'	9,634
Stock Options	'	'	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'	'	'
Shares issuable	8,161	6,570	8,161	6,570
Employee Stock Purchase Plan (ESPP)	'	'	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'	'	'
Shares issuable	71	85	71	85

Collaboration_Arrangements_Add

Collaboration Arrangements - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended	29 Months Ended	6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Mar. 31, 2014	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014
					Merck KGaA	Merck KGaA	Merck KGaA	Merck KGaA	Merck KGaA	Merck KGaA
								United States	Regulatory and Development Milestones	Commercialization Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'
Upfront and milestone payments received to date	'	'	'	'	$12.50	'	$110	'	'	'
Potential future milestones	'	'	'	'	'	'	'	'	100	340
Merck KGaA's percentage share of worldwide development expenses	'	'	'	'	'	70.00%	'	'	'	'
Portion of profits that Company is eligible to participate, depending upon total sales	'	'	'	'	'	'	'	50.00%	'	'
Revenue recognized by the Company	3.7	3.2	7.4	6.1	'	'	'	'	'	'
Company earned a reimbursement for eligible worldwide development expenses	$3.50	$2.50	$9.40	$6.10	'	'	'	'	'	'

Stockholders_Equity_Additional

Stockholders' Equity - Additional Information (Detail) (USD $)	Jun. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014	Jun. 30, 2014
In Millions, except Share data, unless otherwise specified		October 2009 Offering	October 2009 Offering	October 2009 Offering	October 2009 Offering	March 2011 Offering	March 2011 Offering	March 2011 Offering	March 2011 Offering
				Warrants	Warrants			Warrants	Warrants
Class Of Warrant Or Right [Line Items]	'	'	'	'	'	'	'	'	'
Warrants outstanding	8,300,000	4,287,940	4,287,940	'	'	3,993,783	3,993,783	'	'
Warrants exercise price	'	2.05	2.05	'	'	2.46	2.46	'	'
Change in fair value of common stock warrants	'	'	'	$3.40	$3.10	'	'	$3.20	$5

Stockholders_Equity_Outstandin

Stockholders' Equity - Outstanding Warrants Valuation Assumption (Detail) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
October 2009 Offering	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]	'	'
Risk-free interest rate	0.11%	0.13%
Expected life (in years)	'3 months 7 days	'9 months 4 days
Dividend yield	'	'
Volatility	44.00%	49.00%
Stock price	$3.96	$4.67
March 2011 Offering	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]	'	'
Risk-free interest rate	0.47%	0.78%
Expected life (in years)	'1 year 8 months 16 days	'2 years 2 months 16 days
Dividend yield	'	'
Volatility	50.00%	88.00%
Stock price	$3.96	$4.67

Stockholders_Equity_Financial_

Stockholders' Equity - Financial Liabilities Subject to Fair Value Measurements (Detail) (Warrants, USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
October 2009 Warrants	'	'
Class Of Warrant Or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	$8,190	$11,320
October 2009 Warrants | Basis of Fair Value Measurements, Level 3	'	'
Class Of Warrant Or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	8,190	11,320
March 2011 Warrants	'	'
Class Of Warrant Or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	7,109	12,101
March 2011 Warrants | Basis of Fair Value Measurements, Level 3	'	'
Class Of Warrant Or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	7,109	12,101
Total Common Stock Warrants	'	'
Class Of Warrant Or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	15,299	23,421
Total Common Stock Warrants | Basis of Fair Value Measurements, Level 3	'	'
Class Of Warrant Or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	$15,299	$23,421

Stockholders_Equity_Reconcilia

Stockholders' Equity - Reconciliation of Warrant Liability Measured at Fair Value (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Class Of Warrant Or Right [Line Items]	'	'	'	'
Beginning Balance	'	'	$23,421	'
Change in fair value of common stock warrants	-6,665	5,822	-8,122	8,938
Exercise of warrants	'	'	'	'
Ending Balance	$15,299	'	$15,299	'

Stock_Based_Compensation_Stock

Stock Based Compensation - Stock-Based Compensation Expense (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation expense	$1,468	$1,272	$2,734	$2,325
Research and Development	'	'	'	'
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation expense	846	663	1,517	1,197
General and Administrative	'	'	'	'
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation expense	$622	$609	$1,217	$1,128

Stock_Based_Compensation_Weigh

Stock Based Compensation - Weighted-Average Fair Value Valuation Assumptions (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Employee Stock Options	'	'	'	'
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'	'
Risk-free interest rate	1.81%	0.96%	1.82%	1.13%
Expected term (in years)	'5 years 11 months 19 days	'5 years 5 months 19 days	'5 years 11 months 19 days	'5 years 11 months 19 days
Dividend yield	'	'	'	'
Volatility	94.00%	102.00%	94.00%	101.00%
Weighted-average fair value of stock options granted	$2.79	$4.28	$2.89	$4.03
Employee Stock Purchase Plan (ESPP)	'	'	'	'
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'	'
Risk-free interest rate	0.18%	0.20%	0.18%	0.20%
Expected term (in years)	'1 year 3 months	'1 year 3 months	'1 year 3 months	'1 year 3 months
Dividend yield	'	'	'	'
Volatility	53.00%	92.00%	53.00%	92.00%
Weighted-average fair value of ESPP purchase rights	$1.79	$2.44	$1.79	$2.44

Stock_Based_Compensation_Addit

Stock Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		0 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	15-May-14	Jun. 30, 2014	Jun. 30, 2014
					Employee Stock-Based Compensation Expense	Employee Stock-Based Compensation Expense	Employee Stock-Based Compensation Expense	Employee Stock-Based Compensation Expense	2004 Equity Incentive Plan	2004 Equity Incentive Plan	2004 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Stock-based compensation expense	$1,468,000	$1,272,000	$2,734,000	$2,325,000	$1,500,000	$1,200,000	$2,700,000	$2,200,000	'	'	'
Unrecognized compensation cost related to unvested stock-based awards granted to employees under the stock option plans	'	'	'	'	12,700,000	'	12,700,000	'	'	'	'
Unrecognized compensation cost related to unvested stock-based awards granted to employees under the stock option plans, period for recognition	'	'	'	'	'	'	'2 years 8 months 12 days	'	'	'	'
Non-employee stock-based compensation expense	19,000	34,000	55,000	100,000	'	'	'	'	'	'	'
Additional shares authorized for issuance	'	'	'	'	'	'	'	'	6,626,157	1,250,000	100,000
Shares authorized for issuance under the 2014 Equity Incentive Plan	'	'	'	'	'	'	'	'	'	6,000,000	'
Remaining shares available for issuance	'	'	'	'	'	'	'	'	'	4,446,294	261,834
Total intrinsic value of stock options exercised	'	'	200,000	400,000	'	'	'	'	'	'	'
Cash received from stock option exercises	'	'	100,000	200,000	'	'	'	'	'	'	'
Plan participants purchased shares	'	'	'	'	'	'	'	'	'	'	74,062
Average purchase price under 2004 Employee Stock Purchase Plan	'	'	'	'	'	'	'	'	'	'	$3.91
Cash proceeds	'	'	'	'	'	'	'	'	'	'	$300,000

Stock_Based_Compensation_Stock1

Stock Based Compensation - Stock Option Activity Under Equity Incentive Plan (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Number of Shares, Outstanding Beginning Balance	6,526,506
Number of Shares, Granted	1,765,250
Number of Shares, Exercised	-58,560
Number of Shares, Forfeitures	-72,333
Number of Shares, Outstanding Ending Balance	8,160,863
Number of Shares, Vested and expected to vest	8,071,025
Number of Shares, Exercisable	4,450,857
Weighted-Average Exercise Price, Outstanding at beginning of period	$3.66
Weighted-Average Exercise Price, Granted	$3.79
Weighted-Average Exercise Price, Exercised	$1.45
Weighted-Average Exercise Price, Forfeitures	$4.62
Weighted-Average Exercise Price, Outstanding at end of period	$3.69
Weighted-Average Exercise Price, Vested and expected to vest	$3.69
Weighted-Average Exercise Price, Exercisable	$3.04
Weighted-Average Remaining Contractual Term, Outstanding	'7 years 8 months 1 day
Weighted-Average Remaining Contractual Term, Vested and expected to vest	'7 years 7 months 24 days
Weighted-Average Remaining Contractual Term, Exercisable	'6 years 7 months 6 days
Aggregate Intrinsic Value, Outstanding	$8,434,466
Aggregate Intrinsic Value, Vested and expected to vest	8,412,349
Aggregate Intrinsic Value, Exercisable	$7,212,989

Fair_Value_Measurements_and_Ma2

Fair Value Measurements and Marketable Securities - Financial Assets at Fair Value on Recurring Basis (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Total cash equivalents and marketable securities	$75,215	$82,033
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	6,463	4,285
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	68,752	77,748
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	'	'
Money Market Funds	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Total cash equivalents and marketable securities	6,463	4,285
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	6,463	4,285
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	'	'
Certificates of Deposit	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Total cash equivalents and marketable securities	2,844	1,584
Certificates of Deposit | 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	2,844	1,584
Certificates of Deposit | 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	'	'
Corporate Debt Securities	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Total cash equivalents and marketable securities	40,937	49,019
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	40,937	49,019
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	'	'
U. S. Government Securities	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Total cash equivalents and marketable securities	20,023	21,731
U. S. 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	20,023	21,731
U. S. 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	'	'
Municipal Securities	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Total cash equivalents and marketable securities	1,450	2,815
Municipal 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	1,450	2,815
Municipal 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	'	'
Commercial Paper	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Total cash equivalents and marketable securities	3,498	2,599
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	3,498	2,599
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	'	'

Fair_Value_Measurements_and_Ma3

Fair Value Measurements and Marketable Securities - Summary of Company's Available-for-Sale Securities (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost Basis	$68,735	$74,726
Unrealized Gain	23	38
Unrealized Loss	-6	-10
Fair Value	68,752	74,754
Money Market Funds	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost Basis	6,463	4,285
Unrealized Gain	'	'
Unrealized Loss	'	'
Fair Value	6,463	4,285
Certificates of Deposit	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost Basis	2,844	1,584
Unrealized Gain	'	'
Unrealized Loss	'	'
Fair Value	2,844	1,584
Corporate Debt Securities	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost Basis	40,930	49,001
Unrealized Gain	12	25
Unrealized Loss	-5	-7
Fair Value	40,937	49,019
U. S. Government Securities	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost Basis	20,013	21,722
Unrealized Gain	11	12
Unrealized Loss	-1	-3
Fair Value	20,023	21,731
Municipal Securities	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost Basis	1,450	2,814
Unrealized Gain	'	1
Unrealized Loss	'	'
Fair Value	1,450	2,815
Commercial Paper	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost Basis	3,498	2,599
Unrealized Gain	'	'
Unrealized Loss	'	'
Fair Value	3,498	2,599
Marketable Securities Including Cash Equivalents	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost Basis	75,198	82,005
Unrealized Gain	23	38
Unrealized Loss	-6	-10
Fair Value	75,215	82,033
Less Cash Equivalents	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost Basis	6,463	7,279
Unrealized Gain	'	'
Unrealized Loss	'	'
Fair Value	$6,463	$7,279

Fair_Value_Measurements_and_Ma4

Fair Value Measurements and Marketable Securities - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Schedule Of Available For Sale Securities [Line Items]	'	'	'	'
Realized gain or losses	$0	$0	$0	$0
Weighted average maturity for available for sale securities	'	'	'6 years 7 months 6 days	'
Shares of common stock to be purchased with warrants	8,300,000	'	8,300,000	'
Maximum	'	'	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'	'	'
Available for sale securities, longest maturity date	'	'	'2015-11	'

Fair_Value_Measurements_and_Ma5

Fair Value Measurements and Marketable Securities - Marketable Securities with Unrealized Losses (Detail) (USD $)	Jun. 30, 2014
In Thousands, unless otherwise specified
Schedule Of Available For Sale Securities [Line Items]	'
Marketable securities, in loss position for less than twelve months, Fair Value	$20,269
Marketable securities, in loss position for less than twelve months, Unrealized Loss	-6
U. S. Government Securities	'
Schedule Of Available For Sale Securities [Line Items]	'
Marketable securities, in loss position for less than twelve months, Fair Value	8,010
Marketable securities, in loss position for less than twelve months, Unrealized Loss	-1
Corporate Debt Securities	'
Schedule Of Available For Sale Securities [Line Items]	'
Marketable securities, in loss position for less than twelve months, Fair Value	12,259
Marketable securities, in loss position for less than twelve months, Unrealized Loss	($5)

Commitments_and_Contingencies_1

Commitments and Contingencies - Future Rental Payments under Noncancelable Operating Leases (Detail) (USD $)	Jun. 30, 2014
In Thousands, unless otherwise specified
Leases [Abstract]	'
2014	$447
2015	918
2016	953
2017	238
Thereafter	'
Total	$2,556