Humanigen (HGENQ) 10-K13 Mar 142013 FY Annual reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Mar. 07, 2014	Jun. 28, 2013
Document and Entity Information	'	'	'
Entity Registrant Name	'KALOBIOS PHARMACEUTICALS INC	'	'
Entity Central Index Key	'0001293310	'	'
Document Type	'10-K	'	'
Document Period End Date	31-Dec-13	'	'
Amendment Flag	'false	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Filer Category	'Accelerated Filer	'	'
Entity Public Float	'	'	$100
Entity Common Stock, Shares Outstanding	'	32,981,396	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets:	'	'
Cash and cash equivalents	$54,220	$10,947
Marketable securities	22,511	9,351
Contract receivables	44	87
Prepaid expenses and other current assets	742	871
Restricted cash	205	'
Total current assets	77,722	21,256
Restricted cash	'	205
Property and equipment, net	276	230
Deferred offering costs	'	2,803
Other assets	706	45
Total assets	78,704	24,539
Current liabilities:	'	'
Accounts payable	3,197	2,448
Accrued compensation	1,091	628
Deferred rent, short-term	160	101
Accrued research and clinical liabilities	3,309	3,538
Notes payable, short-term	3,182	'
Other accrued liabilities	443	502
Total current liabilities	11,382	7,217
Deferred rent, long-term	'	62
Notes payable, long-term	6,786	9,826
Other liabilities, long-term	'	355
Total liabilities	18,168	17,460
Commitments and contingencies (Note 9)	'	'
Convertible preferred stock, $0.001 par value: no shares and 60,152,555 shares authorized at December 31, 2013, and December 31, 2012, respectively; no shares and 12,329,330 shares issued and outstanding at December 31, 2013, and December 31, 2012, respectively	'	102,023
Stockholders' equity (deficit):	'	'
Common stock, $0.001 par value: 47,500,000 shares and 80,000,000 shares authorized at December 31, 2013, and December 31, 2012, respectively; 32,931,092 and 2,186,695 shares issued and outstanding at December 31, 2013, and December 31, 2012, respectively	33	2
Additional paid-in capital	200,715	3,317
Accumulated other comprehensive income	3	4
Accumulated deficit	-140,215	-98,267
Total stockholders' equity (deficit)	60,536	-94,944
Total liabilities and stockholders' equity (deficit)	$78,704	$24,539

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Consolidated Balance Sheets	'	'
Convertible preferred stock, par value (in dollars per share)	$0.00	$0.00
Convertible preferred stock, shares authorized	0	60,152,555
Convertible preferred stock, shares issued	0	12,329,330
Convertible preferred stock, shares outstanding	0	12,329,330
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	47,500,000	80,000,000
Common stock, shares issued	32,931,092	2,186,695
Common stock, shares outstanding	32,931,092	2,186,695

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Loss (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Consolidated Statements of Comprehensive Loss	'	'	'
Contract revenue	$44	$6,098	$20,255
Operating expenses:	'	'	'
Research and development	32,640	24,519	18,512
General and administrative	8,313	5,061	4,010
Total operating expenses	40,953	29,580	22,522
Loss from operations	-40,909	-23,482	-2,267
Other income (expense):	'	'	'
Interest income	86	44	43
Interest expense	-1,086	-184	'
Other income (expense), net	-39	113	-8
Net loss	-41,948	-23,509	-2,232
Other comprehensive income (loss):	'	'	'
Net unrealized gains (losses) on marketable securities	-1	5	2
Comprehensive loss	($41,949)	($23,504)	($2,230)
Basic and diluted net loss per common share (in dollars per share)	($1.73)	($11.22)	($1.15)
Weighted average common shares outstanding used to calculate basic and diluted net loss per common share (in shares)	24,270,407	2,095,950	1,933,672

Consolidated_Statements_of_Con

Consolidated Statements of Convertible Preferred Stock and Stockholders' Deficit (USD $)	Total	Convertible Preferred Stock	Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
In Thousands, except Share data	Total	Convertible Preferred Stock	Series E Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balances at Dec. 31, 2010	($70,403)	$83,178	'	$2	$2,124	($3)	($72,526)
Balances (in shares) at Dec. 31, 2010	'	10,657,030	'	1,856,765	'	'	'
Issuance of common stock upon exercise of options and vesting of stock awards	67	'	'	'	67	'	'
Issuance of common stock upon exercise of options and vesting of stock awards (in shares)	'	'	'	129,666	'	'	'
Stock-based compensation expense	221	'	'	'	221	'	'
Comprehensive loss	-2,230	'	'	'	'	2	-2,232
Balances at Dec. 31, 2011	-72,345	83,178	'	2	2,412	-1	-74,758
Balances (in shares) at Dec. 31, 2011	'	10,657,030	'	1,986,431	'	'	'
Issuance of common stock upon exercise of options and vesting of stock awards	84	'	'	'	84	'	'
Issuance of common stock upon exercise of options and vesting of stock awards (in shares)	'	'	'	200,264	'	'	'
Issuance of Series E convertible preferred stock, net of issuance costs of $1,404	'	'	18,845	'	'	'	'
Issuance of Series E convertible preferred stock, net of issuance costs of $1,404 (in shares)	'	'	1,672,300	'	'	'	'
Stock-based compensation expense	821	'	'	'	821	'	'
Comprehensive loss	-23,504	'	'	'	'	5	-23,509
Balances at Dec. 31, 2012	-94,944	102,023	'	2	3,317	4	-98,267
Balances (in shares) at Dec. 31, 2012	'	12,329,330	'	2,186,695	'	'	'
Conversion of preferred stock to common stock	102,023	-102,023	'	13	102,010	'	'
Conversion of preferred stock to common stock (in shares)	'	-12,329,330	'	13,211,120	'	'	'
Reclassification of preferred stock warrants liability to additional paid-in capital in conjunction with the conversion of the convertible preferred stock to common stock upon initial public offering	157	'	'	'	157	'	'
Issuance of common stock upon initial public offering, net of issuance costs	61,486	'	'	9	61,477	'	'
Issuance of common stock upon initial public offering, net of issuance costs (in shares)	'	'	'	8,750,000	'	'	'
Issuance of common stock upon equity offering, net of issuance costs	32,029	'	'	9	32,020	'	'
Issuance of common stock upon equity offering, net of issuance costs (in shares)	'	'	'	8,625,000	'	'	'
Issuance of common stock upon exercise of options and vesting of stock awards	164	'	'	'	164	'	'
Issuance of common stock upon exercise of options and vesting of stock awards (in shares)	'	'	'	158,277	'	'	'
Stock-based compensation expense	1,440	'	'	'	1,440	'	'
Issuance of warrants in connection with credit facility	130	'	'	'	130	'	'
Comprehensive loss	-41,949	'	'	'	'	-1	-41,948
Balances at Dec. 31, 2013	$60,536	'	'	$33	$200,715	$3	($140,215)
Balances (in shares) at Dec. 31, 2013	'	'	'	32,931,092	'	'	'

Consolidated_Statements_of_Con1

Consolidated Statements of Convertible Preferred Stock and Stockholders' Deficit (Parenthetical) (Series E Convertible Preferred Stock, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012
Series E Convertible Preferred Stock	'
Issuance of convertible preferred stock, issuance cost	$1,404

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities:	'	'	'
Net loss	($41,948)	($23,509)	($2,232)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'	'
Depreciation and amortization	298	193	484
Amortization of intangible assets	'	111	111
Noncash interest expense	173	22	'
Amortization of premium on marketable securities	416	237	429
Stock based compensation expense	1,440	821	221
Gains on disposal of fixed assets	'	-146	0
Change in fair value of preferred stock warrant liabilities	'	-39	48
Changes in operating assets and liabilities:	'	'	'
Contract receivables	43	90	332
Prepaid expenses and other assets	-435	-291	-11
Accounts payable	1,223	2,007	-908
Accrued compensation	463	-205	95
Deferred revenue	'	-5,630	-13,977
Accrued research and clinical liabilities	-229	2,459	45
Other liabilities	-256	27	11
Deferred rent	-3	-53	22
Net cash used in operating activities	-38,815	-23,906	-15,330
Investing activities:	'	'	'
Purchases of property and equipment	-344	-20	-463
Proceeds from sale of property and equipment	'	170	'
Purchase of marketable securities	-46,852	-25,507	-26,974
Proceeds from maturities of marketable securities	26,035	30,432	36,891
Proceeds from sales of marketable securities	7,241	'	'
Changes in restricted cash	'	'	278
Net cash provided by (used in) investing activities	-13,920	5,075	9,732
Financing activities:	'	'	'
Proceeds from issuance of common stock in initial public offering, net of underwriting costs	65,100	'	'
Proceeds from the sale of common stock, net of underwriting costs	32,430	'	'
Payments of offering related costs	-1,686	-2,329	'
Proceeds from the exercise of stock options	164	84	34
Proceeds from issuance of debt	'	9,840	'
Proceeds from issuances of Series E preferred stock, net	'	18,845	'
Net cash provided by financing activities	96,008	26,440	34
Net increase (decreases) in cash and cash equivalents	43,273	7,609	-5,564
Cash and cash equivalents, beginning of period	10,947	3,338	8,902
Cash and cash equivalents, end of period	54,220	10,947	3,338
Supplemental cash flow disclosure:	'	'	'
Cash paid for interest	890	109	'
Supplemental disclosure of noncash financing activities:	'	'	'
Conversion of preferred stock to common stock and additional paid-in capital	102,023	'	'
Reclassification of preferred stock warrants liability to additional paid-in capital	157	'	'
Issuance of common stock warrants in connection with a loan amendment	130	'	'
Issuance of preferred stock warrant issued with note payable	'	$79	'

Organization_and_Description_o

Organization and Description of Business	12 Months Ended
Organization and Description of Business	Dec. 31, 2013
Organization and Description of Business.	'
Organization and Description of Business	'

	1. Organization and Description of Business

	KaloBios Pharmaceuticals, Inc. (the Company) is a biopharmaceutical company whose primary business is to develop monoclonal antibody therapeutics for diseases that represent a significant burden to society and to patients and their families. The Company's primary clinical focus is on respiratory diseases and cancer. The Company was incorporated on March 15, 2000 in California and reincorporated as a Delaware corporation in September 2001. All of the Company's assets are located in California.

	The Company has incurred significant losses and had an accumulated deficit of $140.2 million as of December 31, 2013. The Company has financed its operations primarily through the sale of equity securities, grants and the payments received under its agreements with Novartis Pharma AG (Novartis) and Sanofi Pasteur S.A. (Sanofi). The Company completed its initial public offering (IPO) in February 2013. To date, none of the Company's product candidates have been approved for sale and therefore the Company has not generated any revenue from product sales. Management expects operating losses to continue for the foreseeable future. As a result, the Company will continue to require additional capital through equity offerings, debt financing and/or payments under new or existing licensing or collaboration agreements. If sufficient funds on acceptable terms are not available when needed, the Company could be required to significantly reduce its operating expenses and delay, reduce the scope of, or eliminate one or more of its development programs.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2013
Summary of Significant Accounting Policies	'
Summary of Significant Accounting Policies	'

	2. Summary of Significant Accounting Policies

	Basis of Presentation and Use of Estimates

	The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and include all adjustments necessary for the presentation of the Company's consolidated financial position, results of operations and cash flows for the periods presented. The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries.

	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements and accompanying notes. Actual results could differ materially from those estimates. The Company believes judgment is involved in determining revenue recognition, the fair value-based measurement of stock-based compensation, accruals and warrant valuations. The Company evaluates its estimates and assumptions as facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ from these estimates and assumptions, and those differences could be material to the consolidated financial statements.

	Concentration of Credit Risk

	Cash, cash equivalents, and marketable securities consist of financial instruments that potentially subject the Company to a concentration of credit risk in the event of a default by the related financial institution holding the securities, to the extent of the value recorded in the balance sheet. The Company invests cash that is not required for immediate operating needs primarily in highly liquid instruments with lower credit risk. The Company has established guidelines relating to the quality, diversification, and maturities of securities to enable the Company to manage its credit risk.

	Fair Value of Financial Instruments

	Cash, accounts payable and accrued liabilities are carried at cost, which approximates fair value given their short-term nature. Marketable securities, cash equivalents, and warrants for convertible preferred stock are carried at fair value.

	The fair value of financial instruments reflects the amounts that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). The fair value hierarchy is based on three levels of inputs that may be used to measure fair value, of which the first two are considered observable, and the third is considered unobservable, as follows:

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

	Level 2—Inputs other than those included in Level 1 that are directly or indirectly observable, such as quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities 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 measures the fair value of financial assets and liabilities using the highest level of inputs that are reasonably available as of the measurement date. The following tables summarize the fair value of financial assets and liabilities (marketable securities and convertible preferred stock warrant liabilities) that are measured at fair value, and the classification by level of input within the fair value hierarchy:


			Fair Value Measurements as of
			December 31, 2013
	(in thousands)		Level 1			Level 2			Level 3		Total
	Investments:
	Money market funds		$	53,511		$	—		$	—	$	53,511
	Federal agency securities			—			12,301			—		12,301
	Commercial paper			—			8,249			—		8,249
	Corporate debt securities			—			1,961			—		1,961


	Total investments		$	53,511		$	22,511		$	—	$	76,022









			Fair Value Measurements as of
			December 31, 2012
	(in thousands)		Level 1			Level 2			Level 3		Total
	Investments:
	Money market funds		$	5,923		$	—		$	—	$	5,923
	U.S. government-backed securities			—			9,351			—		9,351


	Total investments		$	5,923		$	9,351		$	—	$	15,274




	Convertible preferred stock warrant liabilites		$	—		$	—		$	157	$	157





The Company's Level 2 investments include U.S. government-backed securities and corporate securities that are valued based upon observable inputs that may include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data including market research publications. The fair value of the Company's commercial paper is based upon the time to maturity and discounted using the three-month treasury bill rate. The average remaining maturity of the Company's Level 2 investments as of December 31, 2013 is less than nine months and all of these investments are rated by S&P and Moody's at AAA or AA+.

The fair value of the convertible preferred stock warrant liabilities as of December 31, 2012 was calculated using a Black-Scholes option-pricing model, with inputs of the estimated fair value of the underlying common stock at the valuation measurement date of $8.00 per share based upon the price at which common stock was sold in the Company's IPO, the remaining contractual term of the warrants of 2.8 years, the risk-free interest rate of 0.36% based upon the yield of U.S. Treasury instruments with similar durations, the lack of any expected future dividends and the estimated expected volatility of the price of the underlying common stock of 55% based upon the average historic price volatility of a peer group of publicly traded entities.

The following table presents changes in financial instruments measured at fair value using Level 3 inputs:


		Convertible
		Preferred Stock
		Warrant
		Liabilites
		(in thousands)
Balance at December 31, 2011		$	117
Issuances			79
Unrealized gain included in other income (expense), net			(39	)


Balance at December 31, 2012		$	157
Reclassification to additional paid-in capital upon conversion to common stock warrant			(157	)


Balance at December 31, 2013		$	—





The estimated fair value of the notes payable as of December 31, 2013, based upon current market rates for similar borrowings, as measured using Level 3 inputs, approximates the carrying amount as presented on the consolidated balance sheet.

Cash, Cash Equivalents, and Marketable Securities

The Company considers all highly liquid investments with an original maturity of 90 days or less at the time of purchase to be cash equivalents. Cash and cash equivalents consist of deposits with commercial banks in checking, interest-bearing and demand money market accounts. The Company invests in marketable securities consisting primarily of certificates of deposit, money market funds, corporate securities, commercial paper, U.S. government-backed securities and U.S. treasury notes. These securities are classified as available-for-sale and carried at estimated fair value, with unrealized gains and losses reported as part of accumulated other comprehensive income (loss), a separate component of stockholders' deficit. The Company may liquidate any of these investments in order to meet the Company's liquidity needs in the next year.

Realized gains and losses from the sale of marketable securities are calculated using the specific-identification method. Realized gains and losses and declines in value judged to be other-than-temporary are included in interest income (expense), net in the consolidated statements of comprehensive loss. To date, the Company has not recorded any impairment charges on its marketable securities related to other-than-temporary declines in market value. In determining whether a decline in market value is other-than-temporary, various factors are considered, including whether the decline is attributed to a change in credit risk, and whether it is more likely-than-not that the Company will hold the security for a period of time sufficient to allow for an anticipated recovery in market value. The Company realized gains of $2,700 from the sale of marketable securities for the year ended December 31, 2013, and no realized gains or losses from the sale of marketable securities for the years ended December 31, 2012 and 2011.

Restricted Cash

Restricted cash at December 31, 2013 and December 31, 2012 consisted of $0.2 million related to standby letters of credit issued in connection with an operating lease for the Company's corporate headquarters.

Property and Equipment, Net

Property and equipment is stated at cost, less accumulated depreciation and amortization, and depreciated over the estimated useful lives of the respective assets of three years using the straight-line method. Leasehold improvements are amortized on a straight-line basis over the shorter of the useful lives or the noncancelable term of the related lease. Maintenance and repair costs are charged as expense in the statements of comprehensive loss as incurred.

Long-Lived Assets

The Company evaluates the carrying value of its long-lived assets, including intangible assets, whenever events or changes in circumstances indicate that the carrying value of the asset may be impaired. An impairment loss would be recognized when estimated future cash flows expected to result from the use of the asset, including disposition, are less than the carrying value of the asset. To date, the Company has not recorded any impairment charges on its long-lived assets.

The Company's intangible assets consist of intellectual property and know-how acquired, related to developed technology for antibody production, as part of the Company's acquisition of Celscia Therapeutics, Inc., effective January 12, 2004. Such intellectual property and know-how acquired provides the Company with alternative future uses in different research projects. The intellectual property and know-how acquired of $1.0 million was being amortized over the estimated useful life of the technology, which the Company estimated to be nine years. For each of the years ended December 31, 2013, 2012, and 2011, the Company recorded amortization expense of zero, $0.1 million and $0.1, respectively. As of December 31, 2012, the Company's intangible assets were fully amortized.

Deferred Offering Costs

Capitalized deferred offering costs as of December 31, 2012 consisted of legal, accounting, printing and filing fees incurred in the preparation of the Company's Registration Statements on Form 10-12G and Form S-1 as part of the Company's IPO. These deferred offering costs were offset against the IPO proceeds upon the completion of the offering in February 2013. Deferred offering costs associated with the Company's Registration Statement on Form S-3 in October 2013 were capitalized and offset against the proceeds from the October 2013 offering.

Convertible Preferred Stock Warrant Liabilities and Common Stock Warrants

Prior to the Company's IPO, outstanding warrants to purchase shares of the Company's Series B-2 and Series E preferred stock were classified as other liabilities. The initial liability recorded was adjusted for changes in the fair values of the Company's preferred stock warrants during each reporting period and was recorded as a component of other income (expense) in the statement of operations for that period.

Upon the closing of the Company's initial public offering (IPO) and the conversion of the underlying preferred stock to common stock, the Company's warrants to purchase shares of Series B-2 preferred stock were converted into warrants to purchase shares of the Company's common stock. The aggregate fair value of these warrants upon the closing of the IPO was $157,000 which was reclassified from liabilities to additional paid-in capital, a component of stockholders' equity (deficit), and the Company ceased recording any further related periodic fair value adjustments. The Company estimated the fair values of these warrants using the Black-Scholes option-pricing model, based on the inputs for the estimated fair value of the underlying convertible preferred stock at the valuation measurement date, the remaining contractual term of the warrant, risk-free interest rates, expected dividend rates and expected volatility of the price of the underlying convertible preferred stock. These estimates were based on subjective assumptions.

The warrant to purchase shares of the Company's Series E preferred stock expired upon the closing of the Company's IPO in February 2013.

On June 19, 2013, the Company entered into an amendment (the Amendment) to a loan and security agreement (the Agreement) with MidCap Financial, SBIC, LP (MidCap Financial). In connection with the Amendment, the Company issued a warrant to purchase up to 49,548 shares of the Company's common stock with an exercise price of $12.11 per share. The warrant expires on the tenth anniversary of its issuance date.

Research and Development Expenses

Development costs incurred in the research and development of new products are expensed as incurred, including expenses that may or may not be reimbursed under research and development collaboration arrangements. Research and development costs include, but are not limited to, salaries, benefits, stock-based compensation, laboratory supplies, allocated overhead, fees for professional service providers and costs associated with product development efforts, including preclinical studies and clinical trials. Research and development expenses under collaborative agreements approximate or exceed the revenue recognized under such agreements.

The Company estimates preclinical study and clinical trial expenses based on the services performed, pursuant to contracts with research institutions and clinical research organizations that conduct and manage preclinical studies and clinical trials on its behalf. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the receipt of the related services are recorded as prepaid expenses until the services are rendered. In 2012, certain out-of-period adjustments to increase clinical trial expenses by $329,000 were recorded. In 2013, adjustments to increase 2012 clinical trial expenses by $80,000 and other research expenses by $474,000 were recorded. We analyzed and assessed the effect of these adjustments in the annual and interim periods in which they should have been recorded, as well as the effect that these errors had, both individually and in the aggregate, on our reported financial results during the annual and interim periods in which they occurred. This analysis also included their impact on disclosed financial trends and on our "Management's Discussion and Analysis of Financial Condition and Results of Operations" in the affected 2012 Annual Report on Form 10-K. Following this analysis and taking into account both quantitative and qualitative factors, we believe that the uncorrected out-of-period costs that we disclosed in our reports are not material to the respective periods in which the errors occurred.

Revenue Recognition

The Company recognizes revenue when: (i) persuasive evidence of an arrangement exists, (ii) transfer of technology has been completed, delivery has occurred or services have been rendered, (iii) the fee is fixed or determinable, and (iv) collectability is reasonably assured. Payments received in advance of work performed are recorded as deferred revenue and recognized when earned. All revenue recognized to date under the Company's collaborative agreements has been nonrefundable.

Multiple Element Arrangements

The Company evaluates revenue from agreements that have multiple elements to determine whether the components of the arrangement represent separate units of accounting. Management considers whether components of an arrangement represent separate units of accounting based upon whether certain criteria are met, including whether the delivered element has stand-alone value to the customer. To date, all of the Company's research and development collaboration and license agreements have been assessed to have one unit of accounting. Up-front and license fees received for a combined unit of accounting are deferred and recognized ratably over the projected performance period. Nonrefundable fees where the Company has no continuing performance obligations are recognized as revenue when collection is reasonably assured and all other revenue recognition criteria have been met.

Research and Development Services

Internal and external research and development costs incurred in connection with collaboration agreements are recognized as revenue in the same period as the costs are incurred and have been presented on a gross basis because the Company acts as a principal, has the discretion to choose suppliers, bears credit risk, and performs at least part of the services.

Milestones and Other Contingent Payments

The Company has adopted the milestone method as described in FASB ASU 2010-17, Milestone Method of Revenue Recognition. Under the milestone method, contingent consideration received from the achievement of a substantive milestone will be recognized in its entirety in the period in which the milestone is achieved. A milestone is defined as an event having all of the following characteristics: (i) there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved; (ii) the event can only be achieved; based in whole or in part on either the company's performance or a specific outcome resulting from the company's performance; and (iii) if achieved, the event would result in additional payments being due to the company. Contingent payments which do not meet the definition of a milestone are recognized in the same manner as the consideration for the combined unit of accounting. If the Company has no remaining performance obligations under combined unit if accounting, any contingent payments would be recognized as revenue upon the achievement of the triggering event.

The Company's research and development and license agreements provide for payments to be paid to the Company upon the achievement of development milestones or success fees. Given the challenges inherent in developing biologic products, there may be substantial uncertainty as to whether any such milestones would be achieved at the time the agreements are executed. In addition, the Company will evaluate whether the development milestones meet all of the conditions to be considered substantive. The conditions include: (1) the consideration is commensurate with either of the following: (a) the vendor's performance to achieve the milestone or (b) the enhancement of the value of the delivered item or items as a result of a specific outcome resulting from the vendor's performance to achieve the milestone; (2) it relates solely to past performance; and (3) it is reasonable relative to all the deliverables and payment terms within the arrangement. Substantive milestones are recognized as revenue upon achievement of the milestone and when collectability is reasonably assured.

Stock-Based Compensation Expense

The Company measures employee and director stock-based compensation expense for stock awards at the grant date, based on the fair value-based measurement of the award, and the expense is recorded over the related service period, generally the vesting period, net of estimated forfeitures. The Company calculates the fair value-based measurement of stock options using the Black-Scholes valuation model and the single-option method and recognizes expense using the straight-line attribution approach.

The Company accounts for equity instruments issued to nonemployees based on their fair values on the measurement dates using the Black-Scholes option-pricing model. The fair values of the options granted to nonemployees are re-measured as they vest. As a result, the noncash charge to operations for nonemployee options with vesting is affected each reporting period by changes in the fair value of the Company's common stock.

Income Taxes

The Company accounts for income taxes under an asset-and-liability approach. Deferred income taxes reflect the impact of temporary differences between assets and liabilities recognized for tax and financial reporting purposes measured by applying enacted tax rates and laws that will be in effect when the differences are expected to reverse, net operating loss carryforwards and tax credits. Valuation allowances are provided when necessary to reduce net deferred tax assets to an amount that is more likely than not to be realized. The Company's policy is to include interest and penalties related to unrecognized tax benefits within the Company's provision for income taxes.

Comprehensive Loss

Comprehensive loss represents net loss adjusted for the change during the periods presented in unrealized gains and losses on available-for-sale securities less reclassification adjustments for realized gains or losses included in net loss. The unrealized gains or losses are reported on the Consolidated Statements of Comprehensive Loss.

Net Loss Per Common Share

Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares and potentially dilutive securities outstanding for the period determined using the treasury-stock and if-converted methods. For purposes of the diluted net loss per share calculation, convertible preferred stock, stock options and common and preferred stock warrants are considered to be potentially dilutive securities but are excluded from the calculation of diluted net loss per share because their effect would be anti-dilutive and therefore, basic and diluted net loss per share were the same for all periods presented.

The Company's potential dilutive securities which include convertible preferred stock, unvested restricted stock, stock options, and warrants have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per common share and be antidilutive. Therefore, the denominator used to calculate both basic and diluted net loss per common share is the same in all periods presented.

The following shares subject to outstanding potentially dilutive securities have been excluded from the computations of diluted net loss per common share as the effect of including such securities would be antidilutive:


		Year Ended December 31,
		2013			2012			2011
Convertible preferred stock			—			12,329,330			10,657,030
Unvested common stock			—			—			139,033
Warrants to purchase preferred stock			—			72,029			38,997
Options to purchase common stock			1,820,784			1,030,795			1,086,299
Warrants to purchase common stock			88,545


			1,909,329			13,432,154			11,921,359





Deferred Rent

The Company records its costs under facility operating lease agreements as rent expense. Rent expense is recognized on a straight-line basis over the non-cancelable term of the operating lease. The difference between the actual amounts paid and amounts recorded as rent expense is recorded to deferred rent.

Segment Reporting

The Company determines its segment reporting based upon the way the business is organized for making operating decisions and assessing performance. The Company has only one operating segment related to the development of pharmaceutical products.

Investments

Investments	12 Months Ended
Investments	Dec. 31, 2013
Investments	'
Investments	'

	3. Investments

	At December 31, 2013, the amortized cost and fair value of investments, with gross unrealized gains and losses, were as follows:


	(in thousands)	Amortized		Gross		Gross		Fair Value
		Cost		Unrealized		Unrealized
				Gains		Losses
	Money market funds	$	53,511	$	—	$	—	$	53,511
	Federal agency securities		12,301				—		12,301
	Commercial paper		8,246		3		—		8,249
	Corporate debt securities		1,961		—		—		1,961


	Total investments	$	76,019	$	3	$	—	$	76,022




	Reported as:
	Cash and cash equivalents							$	53,306
	Marketable securities								22,511
	Restricted cash								205


	Total investments							$	76,022





	At December 31, 2012, the amortized cost and fair value of investments, with gross unrealized gains and losses, were as follows:


	(in thousands)	Amortized		Gross		Gross		Fair Value
		Cost		Unrealized		Unrealized
				Gains		Losses
	Money market funds	$	5,923	$	—	$	—	$	5,923
	U.S. government-backed securities		9,347		4		—		9,351


	Total investments	$	15,270	$	4	$	—	$	15,274




	Reported as:
	Cash and cash equivalents							$	5,718
	Marketable securities								9,351
	Restricted cash								205


	Total investments							$	15,274





	As of December 31, 2013, all securities had remaining contractual maturities of less than one year.

Property_and_Equipment

Property and Equipment	12 Months Ended
Property and Equipment	Dec. 31, 2013
Property and Equipment	'
Property and Equipment	'

	4. Property and Equipment

	Property and equipment consists of the following:


		December 31
	(In thousands)	2013			2012
	Laboratory equipment	$	1,453		$	1,453
	Computer equipment and software		493			435
	Leasehold improvements, furniture and fixtures		1,571			1,286


			3,517			3,174
	Accumulated depreciation and amortization		(3,241	)		(2,944	)


	Property and equipment, net	$	276		$	230





	Depreciation and amortization expense for the years ended December 31, 2013, 2012 and 2011 was $298,000, $193,000 and $484,000, respectively.

Research_and_Development_Colla

Research and Development Collaboration and License Agreements	12 Months Ended
	Dec. 31, 2013
Research and Development Collaboration and License Agreements	'
Research and Development Collaboration and License Agreements	'

	5. Research and Development Collaboration and License Agreements

	All of the contract revenues recognized in the years ended December 31, 2013, 2012, and 2011 was related to the development and commercialization agreement with Sanofi.

	Sanofi

	In January 2010, the Company and Sanofi entered into an agreement for the development and commercialization of KB001-A, an investigational new biologic for the treatment and prevention of Pseudomonas aeruginosa (Pa) infections (the Sanofi agreement). Under the terms of the Sanofi agreement, the Company received an initial upfront non-refundable payment of $35 million and received an additional non-refundable payment of $5 million that represented a second installment of the upfront fees due to the Company under the agreement upon completion of a sublicense negotiation with a third party in August 2011. The Company may also receive development, regulatory and commercial contingent payments for a potential further $250 million, as well as royalties on eventual product sales, if any. These contingent payments do not meet the definition of milestones since they are based solely on Sanofi's performance and therefore, the milestone method will not be applied to these payments. Sanofi is solely responsible for conducting, at its cost, the research, development, manufacture, and commercialization of the licensed products for the diagnosis, treatment and/or prevention of all human diseases and conditions caused by Pa, except that the Company retains responsibility, at the Company's cost, for developing and promoting the products for the diagnosis, treatment and/or prevention of Pa in patients with cystic fibrosis (CF) or bronchiectasis. Sanofi has an option to obtain rights to participate in the development and promotion of KB001-A and other licensed products for the diagnosis, treatment and/or prevention of Pa in patients with CF or bronchiectasis, either outside of the U.S. or worldwide, at any time up to 90 days after the delivery by the Company to Sanofi of the final clinical study report from the Company's Phase 2 clinical trial of KB001-A in Pa-infected patients with CF.

	The agreement will remain in effect until all payment obligations under the agreement end. Sanofi may terminate the agreement for convenience, and either Sanofi or the Company may terminate the agreement for material breach of the agreement by the other party. In the event Sanofi terminates the agreement for convenience or the Company terminates due to Sanofi's material breach, worldwide rights to develop, manufacture and commercialize licensed products would revert back to the Company, and Sanofi would grant to the Company a license to allow it to develop, manufacture, and commercialize licensed products worldwide, subject to commercially reasonable financial terms to be negotiated by the parties after such termination. In the event that the Company materially breaches the agreement, Sanofi may terminate the agreement or, rather than terminate the agreement, opt to deduct any damages awarded for the Company's breach against future contingent payments and royalties otherwise payable by Sanofi under the agreement.

	The upfront payment of $40 million was recognized over the estimated period of the Company's substantive performance obligations under the agreement. During the three-month period ended March 31, 2012, the Company and Sanofi agreed to amend the 2010 agreement as Sanofi requested that the Company perform additional services. Therefore, the Company revised its estimate to reflect that the substantive performance obligations under the agreement were expected to be completed by June 30, 2012. The substantive performance obligations under the agreement were completed by June 30, 2012.

	Under the terms of the Sanofi agreement, the Company receives specified research and development funding for services performed in connection with KB001-A research and development efforts. Reimbursements received by the Company for these services are recorded as contract revenue when earned as the related services are provided.

	Revenue recognized under the Sanofi agreement was as follows:


		Year Ended December 31,
	(In thousands)	2013		2012		2011
	Contract revenue:
	Amortization of upfront fees	$	—	$	5,630	$	18,977
	Reimbursement for development-related activities		44		468		1,278


	Total contract revenue	$	44	$	6,098	$	20,255





	During the year ended December 31, 2013, the Company recorded research and development expenses related to materials purchased from Sanofi of $1.1 million.

Notes_Payable

Notes Payable	12 Months Ended
Notes Payable	Dec. 31, 2013
Notes Payable	'
Notes Payable	'

	6. Notes Payable

	Loan and Security Agreement

	In September 2012, the Company entered into the Agreement with MidCap Financial, providing for the borrowing of up to $15 million, of which $10 million was required to be drawn. The remaining $5 million may be drawn at the option of the Company. The Agreement provides for the loan to be issued in three tranches: the first tranche of $5 million was issued in September 2012; the second tranche of $5 million was issued in December 2012; and, prior to the amendment described below, the final tranche could have been drawn at the option of the Company no later than June 2013. The loan has a monthly variable interest rate, reset each month, if applicable, as determined by adding to 600 basis points the greater of: (a) one month LIBOR or (b) 3% (the LIBOR floor). Interest on amounts outstanding are payable monthly in arrears. There is an interest only period to December 31, 2013 followed by straight-line principal payments over thirty-six months until December 31, 2016. At the time of final payment, the Company must pay an exit fee of 3% of the drawn amount. Pursuant to the Agreement, the Company provided a first priority security interest in all existing and after-acquired assets, excluding intellectual property. In addition, the terms of the Agreement provided MidCap Financial a warrant to purchase shares of the Company's Series E convertible preferred stock (Series E Preferred) equal to 4% of the amount drawn down under the facility divided by the Series E Preferred exercise price of $12.11 per share. The warrant expired upon the completion of the Company's IPO.

	The Company has the right to prepay all or a portion of the borrowed amounts under the Agreement; however, if the Company exercises this option, the Company must pay a prepayment fee determined by multiplying the outstanding loan amount by 5% if the prepayment occurs on or before December 31, 2014, 2% if the prepayment occurs in 2015 and 1% if the prepayment occurs in the final year. In the event of default, upon which all amounts borrowed become immediately due and payable, the Company will be subject to the prepayment fee. An event of default includes, but is not limited to, an occurrence such as a payment default, a material adverse change, insolvency, or a change of control.

	In connection with the Agreement and the first tranche draw down of $5 million in September 2012 and second tranche draw down of $5 million in December 2012, the Company issued a warrant to MidCap Financial to purchase shares of the Company's Series E Preferred. Contemporaneously with the issuance of the warrant, the Company recorded a debt discount of $79,000.

	Debt issuance costs paid directly to MidCap Financial of $114,000 (financing fees) and the fair value of the warrant issued to MidCap Financial were treated as a discount on the debt and are being accreted using the interest method. Other debt issuance costs for legal fees are included in other assets in the accompanying consolidated balance sheet and are being amortized using the interest method. The accretion of the debt discount and amortization of other debt issuance costs are recorded as non-cash interest expense in the consolidated statements of comprehensive loss.

	In June 2013, the Company entered into the Amendment to extend the draw down date for the final tranche of $5.0 million from June 2013 to May 2014. In addition, the final tranche was changed from an optional draw down to a required draw down. In connection with the Amendment, the Company issued a warrant to purchase up to 49,548 shares of the Company's common stock with an exercise price of $12.11 per share. The warrant expires on the tenth anniversary of its issuance date. The warrants issued to Midcap Financial had an initial fair value of $130,000, which represent financing fees, and are included in other assets in the accompanying consolidated balance sheet and are being amortized as non-cash interest expense over the remaining term of the Agreement using the effective interest method. The Company estimated the fair values of these warrants using the Black-Scholes option-pricing model, based on the inputs for the estimated fair value of the underlying common stock at the valuation measurement date, the contractual term of the warrant, risk-free interest rates, expected dividend rates and expected volatility of the price of the underlying common stock.

	The Company recorded interest expense related to the borrowings of $1.1 million for the year ended December 31, 2013. Included in interest expense for this period was interest on principal, amortization of the debt issuance costs, accretion of debt discount, and the accretion of the final exit fee. For the year ended December 31, 2013, the effective interest rate on the amounts borrowed under the Agreement, including the accretion of the debt discount and the accretion of the final payment, was 10%.

	Future payments as of December 31, 2013 under the Agreement, assuming no adjustments to the variable rate of interest of 9% as of December 31, 2013, are as follows (in thousands):


	2014	$	4,020
	2015		3,724
	2016		3,701


	Total minimum payments		11,445
	Less amount representing interest		(1,445	)


	Notes payable, gross		10,000
	Discount on notes payable		(117	)
	Accretion of the final exit fee payment		85


	Carrying value of notes payable	$	9,968

Warrants_to_Purchase_Common_St

Warrants to Purchase Common Stock	12 Months Ended
Warrants to Purchase Common Stock	Dec. 31, 2013
Warrants to Purchase Common Stock	'
Warrants to Purchase Common Stock	'

	7. Warrants to Purchase Common Stock

	On June 19, 2013, in connection with the Amendment to its debt agreement with MidCap Financial, the Company issued a warrant to purchase up to 49,548 shares of the Company's common stock with an exercise price of $12.11 per share. The warrant expires in June 2023. The Company recorded the initial value of the warrants in equity and other assets in the accompanying consolidated balance sheet, with the deferred other asset to be amortized over the remaining term of the debt using the effective interest method.

	In addition, the Company has outstanding warrants to purchase an aggregate of 38,997 shares of common stock at $5.13 per share which will expire on October 31, 2015.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2013
Commitments and Contingencies	'
Commitments and Contingencies	'

	8. Commitments and Contingencies

	Operating Leases

	The Company's noncancelable operating lease for its current facilities in South San Francisco, California expire in June 2014. In connection with the lease, the Company has issued a standby letter of credit for approximately $0.2 million for the deposit requirement under the terms of the lease. Rent expense is recognized on a straight-line basis over the term of the lease. The Company is also responsible for certain operating expenses. The lease provided an allowance of approximately $0.2 million from the landlord for leasehold improvements that was utilized in the year ended December 31, 2011. This amount has been included in deferred rent in the accompanying balance sheets and is being amortized over the term of the lease, on a straight-line basis.

	In December 2013, the Company entered into a lease agreement for a new facility in South San Francisco, California. The new lease will commence in July 2014 and will expire in 2019. Per the terms of the lease agreement, the Company has the option to terminate the lease after 36 months, subject to additional fees and expenses. At the end of the five year term of the new lease, the Company has the option to extend its term for an additional five years at the then current fair market value rental rate determined in accordance with the terms of the Lease.

	As of December 31, 2013, future minimum lease payments due under our two leases are as follows:


	(in thousands)
	2014	$	1,026
	2015		701
	2016		759
	2017		818
	2018		843


	Total	$	4,147





	In January 2009, the Company entered into a sublease agreement, as amended in April 2009, with a third party to sublease a portion of the Company's facility in South San Francisco, California. The sublease had a 29 month term that began February 1, 2009 and ended June 2011. In January 2011, the third party renewed the sublease for the term beginning July 2011 and ending June 2014. In August and December 2011, the third party amended the sublease to include additional space. In March 2012, the Company entered into a second sublease agreement with another third party to sublease a portion of the Company's facility in South San Francisco, California. The sublease has a 28 month term that began March 1, 2012 and ends June 2014. Under the agreements, the Company will receive sublease payments of $553,000 in 2014. The sublease income received is recorded as an offset to the Company's rent expenses.

	Rent expense, net of sublease income, was zero, $0.1 million and $0.6 million for the years ended December 31, 2013, 2012 and 2011, respectively. Sublease income was $1.1 million, $1.0 million and $0.5 million for the years ended December 31, 2013, 2012 and 2011, respectively.

	Indemnifications

	The Company, as permitted under Delaware law and in accordance with its bylaws, has agreed to indemnify its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company's request in such capacity. The term of the indemnification period is equal to the officer's or director's lifetime.

	The maximum amount of potential future indemnification is unlimited; however, the Company currently holds director and officer liability insurance. This insurance limits the Company's exposure and may enable it to recover a portion of any future amounts paid. The Company believes that the fair value of these indemnification obligations is minimal. Accordingly, the Company has not recognized any liabilities relating to these obligations for any period presented.

	The Company has certain agreements with service providers with which it does business that contain indemnification provisions pursuant to which the Company typically agrees to indemnify the party against certain types of third-party claims. The Company accrues for known indemnification issues when a loss is probable and can be reasonably estimated. The Company would also accrue for estimated incurred but unidentified indemnification issues based on historical activity. As the Company has not incurred any indemnification losses to date, there were no accruals for or expenses related to indemnification issues for any period presented.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2013
Stockholders' Equity	'
Stockholders' Equity	'

	9. Stockholders' Equity

	Initial Public Offering

	The Company closed its initial public offering in February 2013, selling 8,750,000 shares of common stock. The IPO price was $8.00 per share. As a result of the IPO, the Company received gross proceeds of approximately $70.0 million, which resulted in net proceeds to the Company of approximately $61.5 million, after underwriting and other expenses of approximately $8.5 million (comprised of $4.9 million in underwriting discounts and commissions and $3.6 million in other offering expenses).

	Shelf Registration

	In September 2013, the Company filed a shelf registration statement on Form S-3 with the SEC. The Shelf Registration was declared effective by the SEC on September 18, 2013 and permitted the Company to sell, from time to time, up to $100.0 million of common stock, warrants/and or units in one or more offerings and in any combination.

	Common Stock Offering

	In October 2013, under the Shelf Registration, the Company issued and sold 8,625,000 shares of the Company's common stock. The price to the public in this offering was $4.00 per share for gross proceeds of $34.5 million, including the exercise of the overallotment option by the underwriters, which resulted in net proceeds of approximately $32.0 million, after underwriting and other expenses of approximately $2.5 million (comprised of $2.1 million in underwriting discounts and commissions and $0.4 million in other expenses).

	Preferred Stock

	In February 2013, upon the closing of the IPO the Company amended and restated its certificate of incorporation to authorize zero shares of preferred stock upon the completion of its IPO.

	Common Stock

	In February 2013, the Company amended and restated its certificate of incorporation to increase the authorized common stock to 47,500,000 shares upon the completion of the IPO of its common stock.

	The Company had reserved the following shares of common stock for issuance as of December 31, 2013:


	Warrants to purchase common stock			88,545
	Options:
	Outstanding under the 2012 Equity Incentive Plan			1,140,780
	Outstanding under the 2001 Equity Incentive Plan			680,005
	Available for future grants under the 2012 Equity Incentive Plan			1,172,953


	Total common stock reserved for future issuance			3,082,283





	2012 Equity Incentive Plan

	In July 2012, the Company's board of directors adopted the 2012 Equity Incentive Plan (2012 Plan). Under the 2012 Plan, the aggregate number of common shares issued shall not exceed the sum of (a) 1,123,131 common shares, (b) the number of common shares reserved under the 2001 Plan that were not issued or subject to outstanding awards under the 2001 Plan upon its termination, and (c) any common shares subject to outstanding options under the 2001 Plan upon its termination that subsequently expire or lapse unexercised and common shares issued pursuant to awards granted under the 2001 Plan that were outstanding upon its termination and that are subsequently forfeited to or repurchased by the Company; provided, however, that no more than 1,066,975 common shares, in the aggregate, shall be added to the 2012 Equity Incentive Plan pursuant to clauses (b) and (c). In addition, the number of shares reserved for issuance under the 2012 Equity Incentive Plan will be increased automatically on the first business day of each fiscal year of the Company, starting with fiscal year 2013 and ending in fiscal year 2022, by a number equal to the lesser of (a) 5% of the total number of common shares outstanding on December 31 of the prior year, (b) 842,348 common shares, subject to certain adjustments in accordance with the 2012 Equity Incentive Plan, or (c) a number of common shares determined by the Company's board of directors.

	Under the 2012 Plan, the Company may grant shares, stock units, stock appreciation rights, performance cash awards and/or options to employees, directors, consultants, and other service providers. For options, the per share exercise price may not be less than the fair market value of a Company common share on the date of grant. Awards generally vest over four years and expire 10 years from the date of grant. Options generally become exercisable as they vest following the date of grant.

	In general, to the extent that awards under the 2012 Plan are forfeited or lapse without the issuance of shares, those shares will again become available for awards.

	The Company's board of directors has discretion to administer the 2012 Plan. The 2012 Plan provides that in the event of certain significant corporate transactions, each outstanding award will be treated in the manner described in the definitive transaction agreement. Outstanding options granted under the 2001 Plan will become fully vested unless continued or assumed by a surviving entity in a significant corporate transaction. An individual award agreement or any other written agreement between a participant and the Company may provide that an award will be subject to additional acceleration of vesting and exercisability in the event of certain change in control transactions.

	The Company's board of directors may amend or terminate the 2012 Plan at any time. If the Company's board of directors amends the plan, it need not seek stockholder approval of the amendment unless required by applicable law, regulation or rule. The 2012 Plan will continue in effect for 10 years from its adoption date, unless the Company's board of directors decides to terminate the plan earlier.

	2001 Equity Incentive Plan

	Under the Company's 2001 Stock Plan (the 2001 Plan), the Company was able to grant shares and/or options to purchase up to 3,408,247 shares of common stock to employees, directors, consultants, and other service providers at prices not less than the fair market value at the date of grant for incentive stock options and not less than 85% of the fair market value for nonstatutory options. These options generally vest over four years, expire 10 years from the date of grant, and are generally exercisable at any time following the date of grant. Unvested options exercised are subject to the Company's repurchase right that lapses as the options vest.

	Upon the 2012 Equity Incentive Plan taking effect, the 2001 Plan was thereafter terminated in August 2012. However, the awards under the 2001 Plan outstanding as of and subsequent to the termination of the 2001 Plan will continue to be governed by their existing terms.

	Stock Option Activity

	The following table summarizes stock option activity for the year ended December 31, 2013:


			Number of			Weighted-			Weighted-			Aggregate
Shares			Average			Average			Intrinsic Value
			Exercise			Remaining			(in thousands)(2)
			Price			Contractual
			(Per Share)(1)			Term
						(in years)
Balances at December 31, 2012				1,030,795		$	2.68
Options granted				1,242,247			5.61
Options canceled				(293,981	)		4.9
Options exercised(3)				(158,277	)		1.04


Balance at December 31, 2013			1,820,784			4.46			7.62		$	1,515
As of December 31, 2013:
Options vested and expected to vest(4)			1,628,820			4.36			7.43		$	1,493
Exercisable			694,144			2.91			5.17		$	1,366


-1
The weighted average price per share is determined using exercise price per share for stock options.

-2
The aggregate intrinsic value is calculated as the difference between the exercise price of the option and the fair value of our common stock for in-the-money options at December 31, 2013.

-3
The total intrinsic value of stock options exercised was $787,000 and $607,000 for the years ended December 31, 2013 and 2012. The total intrinsic value of stock options exercised for the year ended December 31, 2011 was not significant.

The stock options outstanding and exercisable by exercise price at December 31, 2013 are as follows:


		Stock Options Outstanding
		Stock Options Outstanding						Stock Options Exercisable
					Weighted-
					Average
					Remaining
					Contractual Life
Range of Exercise Prices		Number of			In Years			Weighted-			Number of		Weighted-
		Shares						Average			Shares		Average
								Exercise					Exercise
								Price Per Share					Price Per Share
$0.50 - $1.46			410,600			4.24		$	1.12			397,640	$	1.11
$2.17 - $4.74			481,326			8.05		$	4.24			149,416	$	4.36
$5.25 - $5.75			310,000			8.96		$	5.64			2,222	$	5.57
$6.00			555,165			8.92		$	6			136,678	$	6
$6.42 - $11.36			63,693			8.24		$	8.6			8,188	$	11.36


			1,820,784			7.62		$	4.46			694,144	$	2.91





In February 2010, the Company authorized awards to executive officers for a total of 153,026 shares of common stock. Awards of 56,998 shares of common stock vested in January 2011 based on the attainment in 2010 of certain agreed-upon performance milestones as determined by the Board of Directors. In January 2011, the Company authorized awards to executive officers for a total of 141,795 shares of common stock. In January and July 2012, all outstanding awards of common stock vested based on the attainment in 2011 and 2012 of certain agreed-upon performance milestones as determined by the Board of Directors. The Company recorded total stock-based compensation expense of $401,000 and $52,000 for the years ended December 31, 2012 and 2011, respectively, related to these stock awards.

The total fair value of options vested for the years ended December 31, 2013, 2012 and 2011 were $1.6 million, $97,000 and $61,000, respectively.

Stock-Based Compensation

Our stock-based compensation expense for stock options is estimated at the grant date based on the award's fair value as calculated by the Black-Scholes option pricing model and is recognized as expense over the requisite service period. The Black-Scholes option pricing model requires various highly judgmental assumptions including expected volatility and expected term. The expected volatility is based on the historical stock volatilities of several of our publicly listed peers over a period equal to the expected terms of the options as we do not have a sufficient trading history to use the volatility of our own common stock. To estimate the expected term, we have opted to use the simplified method which is the use of the midpoint of the vesting term and the contractual term. If any of the assumptions used in the Black-Scholes option pricing model changes significantly, stock-based compensation expense may differ materially in the future from that recorded in the current period. In addition, we are required to estimate the expected forfeiture rate and only recognize expense for those shares expected to vest. We estimate the forfeiture rate based on historical experience and our expectations regarding future pre-vesting termination behavior of employees. To the extent our actual forfeiture rate is different from our estimate, stock-based compensation expense is adjusted accordingly.

The weighted-average fair value-based measurement of stock options granted under the Company's stock plans in the years ended December 31, 2013, 2012, and 2011 were $3.03, $6.98 and $0.82 per share, respectively. The fair value-based measurement of stock options granted under the Company's stock plans was estimated at the date of grant using the Black-Scholes model with the following assumptions:


		Year Ended December 31,
		2013			2012			2011
Expected term			6 years			6 years			6 years
Expected volatility			57 - 59	%		57 - 59	%		58 - 60	%
Risk-free interest rate			0.9 - 2.1	%		0.8 - 1.4	%		1.9 - 2.7	%
Expected dividend yield			0	%		0	%		0	%

Total stock-based compensation expense recognized was as follows:


		Year Ended December 31,
(In thousands)		2013			2012			2011
General and administrative		$	731		$	423		$	93
Research and development			709			398			128


		$	1,440		$	821		$	221





At December 31, 2013, the Company had $3.0 million of total unrecognized compensation expense, net of estimated forfeitures, related to outstanding stock options that will be recognized over a weighted-average period of 2.9 years.

Income_Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2013
Income Taxes	'
Income Taxes	'

	10. Income Taxes

	Deferred tax assets and liabilities reflect the net tax effects of net operating loss and tax credit carryovers and the temporary differences between the carrying amounts of assets and liabilities for financial reporting and the amounts used for income tax purposes. Significant components of the Company's deferred tax assets are as follows (in thousands):


			December 31,
			2013			2012
	Deferred tax assets:
	Net operating losses		$	53,099		$	37,162
	Research & other credits			2,227			2,008
	Other			1,447			1,030


	Total deferred tax assets			56,773			40,200
	Valuation allowance			(56,773	)		(40,200	)


	Net deferred tax assets		$	—		$	—





	A reconciliation of the statutory tax rates and the effective tax rates for the years ended December 2013, 2012, and 2011 is as follows:


			Year Ended December 31,
			2013			2012			2011
	Statutory rate			34	%		34	%		34	%
	Valuation Allowance			(33.8	)%		(33.4	)%		(31.0	)%
	Nondeductible Warrant Expense			0	%		0.1	%		0	%
	Nondeductible Stock Compensation			(0.2	)%		(0.6	)%		(2.6	)%
	Other			0	%		0	%		(0.4	)%


	Effective tax rate			0	%		0	%		0	%





	Realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $16.6 million, $9.2 million, $0.8 million during 2013, 2012 and 2011, respectively.

	At December 31, 2013, the Company had federal net operating loss carryforwards of approximately $133.3 million, which expire in the years 2024 through 2033, and state net operating loss carryforwards of approximately $133.3 million, which expire in the years 2015 through 2033.

	At December 31, 2013, the Company had federal research and development credit carryforwards of approximately $2.0 million, which expire in the years 2022 through 2033 and state research and development credit carryforwards of approximately $1.9 million. The state research and development credit carryforwards can be carried forward indefinitely.

	Due to past equity issuances and changes in ownership of the Company's common stock, we believe that our ability to use some our net operating losses and tax credits in the future may be limited. We are conducting an analysis under Sections 382 and 383 of the Internal Revenue Code as enacted by the Tax Reform Act of 1986, and if necessary, we will reduce our net operating losses and tax credits by any applicable limitation when our analysis is complete. The Company recognizes the financial statement effects of a tax position when it is more likely than not, based on the technical merits, that the position will be sustained upon examination.

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


	Beginning at January 1, 2011		$	1,022
	Additions based on tax positions related to current year			3


	Balance at December 31, 2011			1,025
	Additions based on tax positions related to prior year			39
	Additions based on tax positions related to current year			5


	Balance at December 31, 2012			1,069
Additions based on tax positions related to prior year			18
Additions based on tax positions related to current year			109


Balance at December 31, 2013		$	1,196





There were no interest or penalties related to unrecognized tax benefits. Substantially all of the unrecognized tax benefit, if recognized to offset future taxable income would affect the Company's tax rate. The Company does not anticipate that the amount of existing unrecognized tax benefits will significantly increase or decrease within the next 12 months. Because of net operating loss carryforwards, substantially all of the Company's tax years remain open to tax federal and state tax examination.

The Company files income tax returns in the U.S. federal jurisdiction and California. The United States federal corporation income tax returns beginning with the 2000 tax year remain subject to examination by the Internal Revenue Service (IRS). The California corporation income tax returns beginning with the 2000 tax year remain subject to examination by the California Franchise Tax Board.

Employee_Benefit_Plan

Employee Benefit Plan	12 Months Ended
Employee Benefit Plan	Dec. 31, 2013
Employee Benefit Plan	'
Employee Benefit Plan	'

	11. Employee Benefit Plan

	The Company has established a 401(k) tax-deferred savings plan (the 401(k) Plan), which permits participants to make contributions by salary deduction pursuant to Section 401(k) of the Internal Revenue Code. The Company is responsible for administrative costs of the 401(k) Plan. The Company may, at its discretion, make matching contributions to the 401(k) Plan. No employer contributions have been made to date.

Restructuring_Charges

Restructuring Charges	12 Months Ended
Restructuring Charges	Dec. 31, 2013
Restructuring Charges	'
Restructuring Charges	'

	12. Restructuring Charges

	For the year ended December 31, 2011, the Company initiated a reduction in workforce resulting in an aggregate restructuring charge of approximately $1.1 million, consisting of severance and benefit payments for terminated employees. The activity in the accrued restructuring balance, included within accrued compensation on the balance sheet, was as follows for the year ended December 31, 2012 and 2011:


	(in thousands)
	Beginning at December 31, 2010	$	—
	Additions based on charges during the year		1,096
	Deductions based on payments during the year		(641	)


	Balance at December 31, 2011		455
	Deductions based on payments during the period		(455	)


	Balance at December 31, 2012	$	—





	Of the $1.1 million restructuring charges, $0.9 million was included as part of research and development expenses and $0.2 million was included as part of general and administrative expenses in the consolidated statements of comprehensive loss for the year ended December 31, 2011.

Quarterly_Financial_Data_unaud

Quarterly Financial Data (unaudited)	12 Months Ended
Quarterly Financial Data (unaudited)	Dec. 31, 2013
Quarterly Financial Data (unaudited)	'
Quarterly Financial Data (unaudited)	'

	13. Quarterly Financial Data (unaudited)

	The following tables summarize the unaudited quarterly financial data for the last two fiscal years (in thousands, except per share data):


		2013 Quarter Ended
		March 31,			June 30,			September 30,			December 31,
	Total revenue	$	16		$	15		$	9		$	4
	Loss from operations		(8,323	)		(11,571	)		(11,087	)		(9,928	)
	Net loss		(8,574	)		(11,809	)		(11,329	)		(10,236	)
	Basic and dilluted net loss per common share	$	(0.55	)	$	(0.49	)	$	(0.47	)	$	(0.31	)
	Weighted average common shares outstanding used to calculate basic and diluted net loss per common share		15,607,379			24,189,819			24,263,745			32,925,194





		2012 Quarter Ended
		March 31,			June 30,			September 30,			December 31,
	Total revenue	$	3,018		$	2,992		$	69		$	19
	Loss from operations		(1,147	)		(2,113	)		(8,291	)		(11,931	)
	Net loss		(1,131	)		(2,080	)		(8,602	)		(11,696	)
	Basic and dilluted net loss per common share	$	(0.56	)	$	(1.01	)	$	(4.05	)	$	(1.51	)
	Weighted average common shares outstanding used to calculate basic and diluted net loss per common share		2,023,285			2,062,926			2,124,280			7,741,335

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2013

Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and include all adjustments necessary for the presentation of the Company's consolidated financial position, results of operations and cash flows for the periods presented. The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements and accompanying notes. Actual results could differ materially from those estimates. The Company believes judgment is involved in determining revenue recognition, the fair value-based measurement of stock-based compensation, accruals and warrant valuations. The Company evaluates its estimates and assumptions as facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ from these estimates and assumptions, and those differences could be material to the consolidated financial statements.

Concentration of Credit Risk

Cash, cash equivalents, and marketable securities consist of financial instruments that potentially subject the Company to a concentration of credit risk in the event of a default by the related financial institution holding the securities, to the extent of the value recorded in the balance sheet. The Company invests cash that is not required for immediate operating needs primarily in highly liquid instruments with lower credit risk. The Company has established guidelines relating to the quality, diversification, and maturities of securities to enable the Company to manage its credit risk.

Fair Value of Financial Instruments

Cash, accounts payable and accrued liabilities are carried at cost, which approximates fair value given their short-term nature. Marketable securities, cash equivalents, and warrants for convertible preferred stock are carried at fair value.

The fair value of financial instruments reflects the amounts that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). The fair value hierarchy is based on three levels of inputs that may be used to measure fair value, of which the first two are considered observable, and the third is considered unobservable, as follows:

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

Level 2—Inputs other than those included in Level 1 that are directly or indirectly observable, such as quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities 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 measures the fair value of financial assets and liabilities using the highest level of inputs that are reasonably available as of the measurement date. The following tables summarize the fair value of financial assets and liabilities (marketable securities and convertible preferred stock warrant liabilities) that are measured at fair value, and the classification by level of input within the fair value hierarchy:

Fair Value Measurements as of

December 31, 2013

(in thousands)

Level 1

Level 2

Level 3

Total

Investments:

Money market funds

53,511

—

53,511

Federal agency securities

—

12,301

—

12,301

Commercial paper

—

8,249

—

8,249

Corporate debt securities

—

1,961

—

1,961

Total investments

53,511

22,511

—

76,022

Fair Value Measurements as of

December 31, 2012

(in thousands)

Level 1

Level 2

Level 3

Total

Investments:

Money market funds

5,923

—

5,923

U.S. government-backed securities

—

9,351

—

9,351

Total investments

5,923

9,351

—

15,274

Convertible preferred stock warrant liabilites

—

157

The Company's Level 2 investments include U.S. government-backed securities and corporate securities that are valued based upon observable inputs that may include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data including market research publications. The fair value of the Company's commercial paper is based upon the time to maturity and discounted using the three-month treasury bill rate. The average remaining maturity of the Company's Level 2 investments as of December 31, 2013 is less than nine months and all of these investments are rated by S&P and Moody's at AAA or AA+.

The fair value of the convertible preferred stock warrant liabilities as of December 31, 2012 was calculated using a Black-Scholes option-pricing model, with inputs of the estimated fair value of the underlying common stock at the valuation measurement date of $8.00 per share based upon the price at which common stock was sold in the Company's IPO, the remaining contractual term of the warrants of 2.8 years, the risk-free interest rate of 0.36% based upon the yield of U.S. Treasury instruments with similar durations, the lack of any expected future dividends and the estimated expected volatility of the price of the underlying common stock of 55% based upon the average historic price volatility of a peer group of publicly traded entities.

The following table presents changes in financial instruments measured at fair value using Level 3 inputs:

Convertible

Preferred Stock

Warrant

Liabilites

(in thousands)

Balance at December 31, 2011

117

Issuances

Unrealized gain included in other income (expense), net

(39

)

Balance at December 31, 2012

157

Reclassification to additional paid-in capital upon conversion to common stock warrant

(157

)

Balance at December 31, 2013

—

The estimated fair value of the notes payable as of December 31, 2013, based upon current market rates for similar borrowings, as measured using Level 3 inputs, approximates the carrying amount as presented on the consolidated balance sheet.

Cash, Cash Equivalents, and Marketable Securities

The Company considers all highly liquid investments with an original maturity of 90 days or less at the time of purchase to be cash equivalents. Cash and cash equivalents consist of deposits with commercial banks in checking, interest-bearing and demand money market accounts. The Company invests in marketable securities consisting primarily of certificates of deposit, money market funds, corporate securities, commercial paper, U.S. government-backed securities and U.S. treasury notes. These securities are classified as available-for-sale and carried at estimated fair value, with unrealized gains and losses reported as part of accumulated other comprehensive income (loss), a separate component of stockholders' deficit. The Company may liquidate any of these investments in order to meet the Company's liquidity needs in the next year.

Realized gains and losses from the sale of marketable securities are calculated using the specific-identification method. Realized gains and losses and declines in value judged to be other-than-temporary are included in interest income (expense), net in the consolidated statements of comprehensive loss. To date, the Company has not recorded any impairment charges on its marketable securities related to other-than-temporary declines in market value. In determining whether a decline in market value is other-than-temporary, various factors are considered, including whether the decline is attributed to a change in credit risk, and whether it is more likely-than-not that the Company will hold the security for a period of time sufficient to allow for an anticipated recovery in market value. The Company realized gains of $2,700 from the sale of marketable securities for the year ended December 31, 2013, and no realized gains or losses from the sale of marketable securities for the years ended December 31, 2012 and 2011.

Restricted Cash

Restricted cash at December 31, 2013 and December 31, 2012 consisted of $0.2 million related to standby letters of credit issued in connection with an operating lease for the Company's corporate headquarters.

Property and Equipment, Net

Property and equipment is stated at cost, less accumulated depreciation and amortization, and depreciated over the estimated useful lives of the respective assets of three years using the straight-line method. Leasehold improvements are amortized on a straight-line basis over the shorter of the useful lives or the noncancelable term of the related lease. Maintenance and repair costs are charged as expense in the statements of comprehensive loss as incurred.

Long-Lived Assets

The Company evaluates the carrying value of its long-lived assets, including intangible assets, whenever events or changes in circumstances indicate that the carrying value of the asset may be impaired. An impairment loss would be recognized when estimated future cash flows expected to result from the use of the asset, including disposition, are less than the carrying value of the asset. To date, the Company has not recorded any impairment charges on its long-lived assets.

The Company's intangible assets consist of intellectual property and know-how acquired, related to developed technology for antibody production, as part of the Company's acquisition of Celscia Therapeutics, Inc., effective January 12, 2004. Such intellectual property and know-how acquired provides the Company with alternative future uses in different research projects. The intellectual property and know-how acquired of $1.0 million was being amortized over the estimated useful life of the technology, which the Company estimated to be nine years. For each of the years ended December 31, 2013, 2012, and 2011, the Company recorded amortization expense of zero, $0.1 million and $0.1, respectively. As of December 31, 2012, the Company's intangible assets were fully amortized.

Deferred Offering Costs

Capitalized deferred offering costs as of December 31, 2012 consisted of legal, accounting, printing and filing fees incurred in the preparation of the Company's Registration Statements on Form 10-12G and Form S-1 as part of the Company's IPO. These deferred offering costs were offset against the IPO proceeds upon the completion of the offering in February 2013. Deferred offering costs associated with the Company's Registration Statement on Form S-3 in October 2013 were capitalized and offset against the proceeds from the October 2013 offering.

Convertible Preferred Stock Warrant Liabilities and Common Stock Warrants

Prior to the Company's IPO, outstanding warrants to purchase shares of the Company's Series B-2 and Series E preferred stock were classified as other liabilities. The initial liability recorded was adjusted for changes in the fair values of the Company's preferred stock warrants during each reporting period and was recorded as a component of other income (expense) in the statement of operations for that period.

Upon the closing of the Company's initial public offering (IPO) and the conversion of the underlying preferred stock to common stock, the Company's warrants to purchase shares of Series B-2 preferred stock were converted into warrants to purchase shares of the Company's common stock. The aggregate fair value of these warrants upon the closing of the IPO was $157,000 which was reclassified from liabilities to additional paid-in capital, a component of stockholders' equity (deficit), and the Company ceased recording any further related periodic fair value adjustments. The Company estimated the fair values of these warrants using the Black-Scholes option-pricing model, based on the inputs for the estimated fair value of the underlying convertible preferred stock at the valuation measurement date, the remaining contractual term of the warrant, risk-free interest rates, expected dividend rates and expected volatility of the price of the underlying convertible preferred stock. These estimates were based on subjective assumptions.

The warrant to purchase shares of the Company's Series E preferred stock expired upon the closing of the Company's IPO in February 2013.

On June 19, 2013, the Company entered into an amendment (the Amendment) to a loan and security agreement (the Agreement) with MidCap Financial, SBIC, LP (MidCap Financial). In connection with the Amendment, the Company issued a warrant to purchase up to 49,548 shares of the Company's common stock with an exercise price of $12.11 per share. The warrant expires on the tenth anniversary of its issuance date.

Research and Development Expenses

Development costs incurred in the research and development of new products are expensed as incurred, including expenses that may or may not be reimbursed under research and development collaboration arrangements. Research and development costs include, but are not limited to, salaries, benefits, stock-based compensation, laboratory supplies, allocated overhead, fees for professional service providers and costs associated with product development efforts, including preclinical studies and clinical trials. Research and development expenses under collaborative agreements approximate or exceed the revenue recognized under such agreements.

The Company estimates preclinical study and clinical trial expenses based on the services performed, pursuant to contracts with research institutions and clinical research organizations that conduct and manage preclinical studies and clinical trials on its behalf. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the receipt of the related services are recorded as prepaid expenses until the services are rendered. In 2012, certain out-of-period adjustments to increase clinical trial expenses by $329,000 were recorded. In 2013, adjustments to increase 2012 clinical trial expenses by $80,000 and other research expenses by $474,000 were recorded. We analyzed and assessed the effect of these adjustments in the annual and interim periods in which they should have been recorded, as well as the effect that these errors had, both individually and in the aggregate, on our reported financial results during the annual and interim periods in which they occurred. This analysis also included their impact on disclosed financial trends and on our "Management's Discussion and Analysis of Financial Condition and Results of Operations" in the affected 2012 Annual Report on Form 10-K. Following this analysis and taking into account both quantitative and qualitative factors, we believe that the uncorrected out-of-period costs that we disclosed in our reports are not material to the respective periods in which the errors occurred.

Revenue Recognition

The Company recognizes revenue when: (i) persuasive evidence of an arrangement exists, (ii) transfer of technology has been completed, delivery has occurred or services have been rendered, (iii) the fee is fixed or determinable, and (iv) collectability is reasonably assured. Payments received in advance of work performed are recorded as deferred revenue and recognized when earned. All revenue recognized to date under the Company's collaborative agreements has been nonrefundable.

Multiple Element Arrangements

The Company evaluates revenue from agreements that have multiple elements to determine whether the components of the arrangement represent separate units of accounting. Management considers whether components of an arrangement represent separate units of accounting based upon whether certain criteria are met, including whether the delivered element has stand-alone value to the customer. To date, all of the Company's research and development collaboration and license agreements have been assessed to have one unit of accounting. Up-front and license fees received for a combined unit of accounting are deferred and recognized ratably over the projected performance period. Nonrefundable fees where the Company has no continuing performance obligations are recognized as revenue when collection is reasonably assured and all other revenue recognition criteria have been met.

Research and Development Services

Internal and external research and development costs incurred in connection with collaboration agreements are recognized as revenue in the same period as the costs are incurred and have been presented on a gross basis because the Company acts as a principal, has the discretion to choose suppliers, bears credit risk, and performs at least part of the services.

Milestones and Other Contingent Payments

The Company has adopted the milestone method as described in FASB ASU 2010-17, Milestone Method of Revenue Recognition. Under the milestone method, contingent consideration received from the achievement of a substantive milestone will be recognized in its entirety in the period in which the milestone is achieved. A milestone is defined as an event having all of the following characteristics: (i) there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved; (ii) the event can only be achieved; based in whole or in part on either the company's performance or a specific outcome resulting from the company's performance; and (iii) if achieved, the event would result in additional payments being due to the company. Contingent payments which do not meet the definition of a milestone are recognized in the same manner as the consideration for the combined unit of accounting. If the Company has no remaining performance obligations under combined unit if accounting, any contingent payments would be recognized as revenue upon the achievement of the triggering event.

The Company's research and development and license agreements provide for payments to be paid to the Company upon the achievement of development milestones or success fees. Given the challenges inherent in developing biologic products, there may be substantial uncertainty as to whether any such milestones would be achieved at the time the agreements are executed. In addition, the Company will evaluate whether the development milestones meet all of the conditions to be considered substantive. The conditions include: (1) the consideration is commensurate with either of the following: (a) the vendor's performance to achieve the milestone or (b) the enhancement of the value of the delivered item or items as a result of a specific outcome resulting from the vendor's performance to achieve the milestone; (2) it relates solely to past performance; and (3) it is reasonable relative to all the deliverables and payment terms within the arrangement. Substantive milestones are recognized as revenue upon achievement of the milestone and when collectability is reasonably assured.

Stock-Based Compensation Expense

The Company measures employee and director stock-based compensation expense for stock awards at the grant date, based on the fair value-based measurement of the award, and the expense is recorded over the related service period, generally the vesting period, net of estimated forfeitures. The Company calculates the fair value-based measurement of stock options using the Black-Scholes valuation model and the single-option method and recognizes expense using the straight-line attribution approach.

The Company accounts for equity instruments issued to nonemployees based on their fair values on the measurement dates using the Black-Scholes option-pricing model. The fair values of the options granted to nonemployees are re-measured as they vest. As a result, the noncash charge to operations for nonemployee options with vesting is affected each reporting period by changes in the fair value of the Company's common stock.

Income Taxes

The Company accounts for income taxes under an asset-and-liability approach. Deferred income taxes reflect the impact of temporary differences between assets and liabilities recognized for tax and financial reporting purposes measured by applying enacted tax rates and laws that will be in effect when the differences are expected to reverse, net operating loss carryforwards and tax credits. Valuation allowances are provided when necessary to reduce net deferred tax assets to an amount that is more likely than not to be realized. The Company's policy is to include interest and penalties related to unrecognized tax benefits within the Company's provision for income taxes.

Comprehensive Loss

Comprehensive loss represents net loss adjusted for the change during the periods presented in unrealized gains and losses on available-for-sale securities less reclassification adjustments for realized gains or losses included in net loss. The unrealized gains or losses are reported on the Consolidated Statements of Comprehensive Loss.

Net Loss Per Common Share

Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares and potentially dilutive securities outstanding for the period determined using the treasury-stock and if-converted methods. For purposes of the diluted net loss per share calculation, convertible preferred stock, stock options and common and preferred stock warrants are considered to be potentially dilutive securities but are excluded from the calculation of diluted net loss per share because their effect would be anti-dilutive and therefore, basic and diluted net loss per share were the same for all periods presented.

The Company's potential dilutive securities which include convertible preferred stock, unvested restricted stock, stock options, and warrants have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per common share and be antidilutive. Therefore, the denominator used to calculate both basic and diluted net loss per common share is the same in all periods presented.

The following shares subject to outstanding potentially dilutive securities have been excluded from the computations of diluted net loss per common share as the effect of including such securities would be antidilutive:

Year Ended December 31,

2013

2012

2011

Convertible preferred stock

—

12,329,330

10,657,030

Unvested common stock

—

139,033

Warrants to purchase preferred stock

—

72,029

38,997

Options to purchase common stock

1,820,784

1,030,795

1,086,299

Warrants to purchase common stock

88,545

1,909,329

13,432,154

11,921,359

Deferred Rent

The Company records its costs under facility operating lease agreements as rent expense. Rent expense is recognized on a straight-line basis over the non-cancelable term of the operating lease. The difference between the actual amounts paid and amounts recorded as rent expense is recorded to deferred rent.

Segment Reporting

The Company determines its segment reporting based upon the way the business is organized for making operating decisions and assessing performance. The Company has only one operating segment related to the development of pharmaceutical products.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
Summary of Significant Accounting Policies (Tables)	Dec. 31, 2013
Summary of Significant Accounting Policies	'
Schedule of fair value of financial assets and liabilities measured at fair value and classification by level of input	'




		Fair Value Measurements as of
		December 31, 2013
	(in thousands)	Level 1			Level 2		Level 3		Total
	Investments:
	Money market funds	$	53,511		$	—	$	—	$	53,511
	Federal agency securities		—			12,301		—		12,301
	Commercial paper		—			8,249		—		8,249
	Corporate debt securities		—			1,961		—		1,961


	Total investments	$	53,511		$	22,511	$	—	$	76,022








		Fair Value Measurements as of
		December 31, 2012
	(in thousands)	Level 1			Level 2		Level 3		Total
	Investments:
	Money market funds	$	5,923		$	—	$	—	$	5,923
	U.S. government-backed securities		—			9,351		—		9,351


	Total investments	$	5,923		$	9,351	$	—	$	15,274




	Convertible preferred stock warrant liabilites	$	—		$	—	$	157	$	157




Schedule of changes in financial instruments measured at fair value using Level 3 inputs	'




		Convertible
		Preferred Stock
		Warrant
		Liabilites
		(in thousands)
	Balance at December 31, 2011	$	117
	Issuances		79
	Unrealized gain included in other income (expense), net		(39	)


	Balance at December 31, 2012	$	157
	Reclassification to additional paid-in capital upon conversion to common stock warrant		(157	)


	Balance at December 31, 2013	$	—




Schedule of antidilutive securities excluded from computations of diluted net loss per common share	'




		Year Ended December 31,
		2013			2012		2011
	Convertible preferred stock		—			12,329,330		10,657,030
	Unvested common stock		—			—		139,033
	Warrants to purchase preferred stock		—			72,029		38,997
	Options to purchase common stock		1,820,784			1,030,795		1,086,299
	Warrants to purchase common stock		88,545


			1,909,329			13,432,154		11,921,359

Investments_Tables

Investments (Tables)	12 Months Ended
Investments (Tables)	Dec. 31, 2013
Investments	'
Schedule of amortized cost and fair value of investments, with gross unrealized gains and losses	'

	At December 31, 2013, the amortized cost and fair value of investments, with gross unrealized gains and losses, were as follows:


	(in thousands)	Amortized		Gross		Gross		Fair Value
		Cost		Unrealized		Unrealized
				Gains		Losses
	Money market funds	$	53,511	$	—	$	—	$	53,511
	Federal agency securities		12,301				—		12,301
	Commercial paper		8,246		3		—		8,249
	Corporate debt securities		1,961		—		—		1,961


	Total investments	$	76,019	$	3	$	—	$	76,022




	Reported as:
	Cash and cash equivalents							$	53,306
	Marketable securities								22,511
	Restricted cash								205


	Total investments							$	76,022





	At December 31, 2012, the amortized cost and fair value of investments, with gross unrealized gains and losses, were as follows:


	(in thousands)	Amortized		Gross		Gross		Fair Value
		Cost		Unrealized		Unrealized
				Gains		Losses
	Money market funds	$	5,923	$	—	$	—	$	5,923
	U.S. government-backed securities		9,347		4		—		9,351


	Total investments	$	15,270	$	4	$	—	$	15,274




	Reported as:
	Cash and cash equivalents							$	5,718
	Marketable securities								9,351
	Restricted cash								205


	Total investments							$	15,274

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
Property and Equipment (Tables)	Dec. 31, 2013
Property and Equipment	'
Schedule of property and equipment	'

		December 31
	(In thousands)	2013			2012
	Laboratory equipment	$	1,453		$	1,453
	Computer equipment and software		493			435
	Leasehold improvements, furniture and fixtures		1,571			1,286


			3,517			3,174
	Accumulated depreciation and amortization		(3,241	)		(2,944	)


	Property and equipment, net	$	276		$	230

Research_and_Development_Colla1

Research and Development Collaboration and License Agreements (Tables)	12 Months Ended
	Dec. 31, 2013
Research and Development Collaboration and License Agreements	'
Schedule of revenue recognized under the Sanofi agreement	'




		Year Ended December 31,
	(In thousands)	2013		2012		2011
	Contract revenue:
	Amortization of upfront fees	$	—	$	5,630	$	18,977
	Reimbursement for development-related activities		44		468		1,278


	Total contract revenue	$	44	$	6,098	$	20,255

Notes_Payable_Tables

Notes Payable (Tables)	12 Months Ended
Notes Payable (Tables)	Dec. 31, 2013
Notes Payable	'
Schedule of future payments under the agreement, assuming no adjustments to the variable rate of interest	'

	Future payments as of December 31, 2013 under the Agreement, assuming no adjustments to the variable rate of interest of 9% as of December 31, 2013, are as follows (in thousands):


	2014	$	4,020
	2015		3,724
	2016		3,701


	Total minimum payments		11,445
	Less amount representing interest		(1,445	)


	Notes payable, gross		10,000
	Discount on notes payable		(117	)
	Accretion of the final exit fee payment		85


	Carrying value of notes payable	$	9,968

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
Commitments and Contingencies (Tables)	Dec. 31, 2013
Commitments and Contingencies	'
Schedule of future minimum lease payments and sublease payments under the agreements	'




	(in thousands)
	2014	$	1,026
	2015		701
	2016		759
	2017		818
	2018		843


	Total	$	4,147

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	12 Months Ended
Stockholders' Equity (Tables)	Dec. 31, 2013
Stockholders' Equity	'
Schedule of shares of common stock reserved for issuance	'




	Warrants to purchase common stock		88,545
	Options:
	Outstanding under the 2012 Equity Incentive Plan		1,140,780
	Outstanding under the 2001 Equity Incentive Plan		680,005
	Available for future grants under the 2012 Equity Incentive Plan		1,172,953


	Total common stock reserved for future issuance		3,082,283




Summary of stock option activity	'




		Number of			Weighted-			Weighted-			Aggregate
		Shares			Average			Average			Intrinsic Value
					Exercise			Remaining			(in thousands)(2)
					Price			Contractual
					(Per Share)(1)			Term
								(in years)
	Balances at December 31, 2012		1,030,795		$	2.68
	Options granted		1,242,247			5.61
	Options canceled		(293,981	)		4.9
	Options exercised(3)		(158,277	)		1.04


	Balance at December 31, 2013		1,820,784			4.46			7.62		$	1,515
	As of December 31, 2013:
	Options vested and expected to vest(4)		1,628,820			4.36			7.43		$	1,493
	Exercisable		694,144			2.91			5.17		$	1,366


	-1
	The weighted average price per share is determined using exercise price per share for stock options.

	-2
	The aggregate intrinsic value is calculated as the difference between the exercise price of the option and the fair value of our common stock for in-the-money options at December 31, 2013.

	-3
	The total intrinsic value of stock options exercised was $787,000 and $607,000 for the years ended December 31, 2013 and 2012. The total intrinsic value of stock options exercised for the year ended December 31, 2011 was not significant.

Schedule of stock options outstanding and exercisable by exercise price	'




		Stock Options Outstanding
		Stock Options Outstanding						Stock Options Exercisable
					Weighted-
					Average
					Remaining
					Contractual Life
	Range of Exercise Prices	Number of			In Years			Weighted-			Number of		Weighted-
		Shares						Average			Shares		Average
								Exercise					Exercise
								Price Per Share					Price Per Share
	$0.50 - $1.46		410,600			4.24		$	1.12			397,640	$	1.11
	$2.17 - $4.74		481,326			8.05		$	4.24			149,416	$	4.36
	$5.25 - $5.75		310,000			8.96		$	5.64			2,222	$	5.57
	$6.00		555,165			8.92		$	6			136,678	$	6
	$6.42 - $11.36		63,693			8.24		$	8.6			8,188	$	11.36


			1,820,784			7.62		$	4.46			694,144	$	2.91




Schedule of fair value-based measurement of stock options granted under the entity's stock plans estimated using Black-Scholes model	'




		Year Ended December 31,
		2013			2012			2011
	Expected term		6 years			6 years			6 years
	Expected volatility		57 - 59	%		57 - 59	%		58 - 60	%
	Risk-free interest rate		0.9 - 2.1	%		0.8 - 1.4	%		1.9 - 2.7	%
	Expected dividend yield		0	%		0	%		0	%
Schedule of total stock-based compensation expense recognized	'




		Year Ended December 31,
	(In thousands)	2013			2012			2011
	General and administrative	$	731		$	423		$	93
	Research and development		709			398			128


		$	1,440		$	821		$	221

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2013
Income Taxes	'
Schedule of significant components of deferred tax assets	'

	Significant components of the Company's deferred tax assets are as follows (in thousands):


		December 31,
		2013			2012
	Deferred tax assets:
	Net operating losses	$	53,099		$	37,162
	Research & other credits		2,227			2,008
	Other		1,447			1,030


	Total deferred tax assets		56,773			40,200
	Valuation allowance		(56,773	)		(40,200	)


	Net deferred tax assets	$	—		$	—




Schedule of reconciliation of the statutory tax rates and the effective tax rates	'




		Year Ended December 31,
		2013			2012			2011
	Statutory rate		34	%		34	%		34	%
	Valuation Allowance		(33.8	)%		(33.4	)%		(31.0	)%
	Nondeductible Warrant Expense		0	%		0.1	%		0	%
	Nondeductible Stock Compensation		(0.2	)%		(0.6	)%		(2.6	)%
	Other		0	%		0	%		(0.4	)%


	Effective tax rate		0	%		0	%		0	%




Reconciliation of Beginning And Ending Amount Of Unrecognized Tax Benefits	'

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


	Beginning at January 1, 2011	$	1,022
	Additions based on tax positions related to current year		3


	Balance at December 31, 2011		1,025
	Additions based on tax positions related to prior year		39
	Additions based on tax positions related to current year		5


	Balance at December 31, 2012		1,069
	Additions based on tax positions related to prior year		18
	Additions based on tax positions related to current year		109


	Balance at December 31, 2013	$	1,196

Restructuring_Charges_Tables

Restructuring Charges (Tables)	12 Months Ended
Restructuring Charges (Tables)	Dec. 31, 2013
Restructuring Charges	'
Schedule of activity in accrued restructuring balance, included within accrued compensation	'




	(in thousands)
	Beginning at December 31, 2010	$	—
	Additions based on charges during the year		1,096
	Deductions based on payments during the year		(641	)


	Balance at December 31, 2011		455
	Deductions based on payments during the period		(455	)


	Balance at December 31, 2012	$	—

Quarterly_Financial_Data_unaud1

Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
Quarterly Financial Data (unaudited) (Tables)	Dec. 31, 2013
Quarterly Financial Data (unaudited)	'
Summary of the unaudited quarterly financial data	'

	The following tables summarize the unaudited quarterly financial data for the last two fiscal years (in thousands, except per share data):


		2013 Quarter Ended
		March 31,			June 30,			September 30,			December 31,
	Total revenue	$	16		$	15		$	9		$	4
	Loss from operations		(8,323	)		(11,571	)		(11,087	)		(9,928	)
	Net loss		(8,574	)		(11,809	)		(11,329	)		(10,236	)
	Basic and dilluted net loss per common share	$	(0.55	)	$	(0.49	)	$	(0.47	)	$	(0.31	)
	Weighted average common shares outstanding used to calculate basic and diluted net loss per common share		15,607,379			24,189,819			24,263,745			32,925,194




		2012 Quarter Ended
		March 31,			June 30,			September 30,			December 31,
	Total revenue	$	3,018		$	2,992		$	69		$	19
	Loss from operations		(1,147	)		(2,113	)		(8,291	)		(11,931	)
	Net loss		(1,131	)		(2,080	)		(8,602	)		(11,696	)
	Basic and dilluted net loss per common share	$	(0.56	)	$	(1.01	)	$	(4.05	)	$	(1.51	)
	Weighted average common shares outstanding used to calculate basic and diluted net loss per common share		2,023,285			2,062,926			2,124,280			7,741,335

Organization_and_Description_o1

Organization and Description of Business (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
	item	Dec. 31, 2012
Organization and Description of Business.	'	'
Accumulated deficit	$140,215	$98,267
Number of product candidates approved for sale	0	'

Summary_of_Significant_Account3

Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jun. 19, 2013	Jun. 19, 2013
	segment			Intellectual Property And know-how	Intellectual Property And know-how	Intellectual Property And know-how	Loan and Security Agreement	Loan and Security Agreement
								Maximum
Summary of Significant Accounting Policies	'	'	'	'	'	'	'	'
Realized gains or losses from sale of marketable securities	$2,700	$0	$0	'	'	'	'	'
Restricted cash current, standby letters of credit	200,000	200,000	'	'	'	'	'	'
Property and equipment, estimated useful lives	'3 years	'	'	'	'	'	'	'
Intangible asset, acquired value	'	'	'	1,000,000	'	'	'	'
Intangible asset, estimated useful life	'	'	'	'9 years	'	'	'	'
Intangible asset, amortization expense	'	111,000	111,000	0	100,000	100,000	'	'
Reclassification of preferred stock warrants liability to additional paid-in capital	157,000	'	'	'	'	'	'	'
Issuance of warrant to purchase shares of common stock	38,997	'	'	'	'	'	'	49,548
Exercise price of warrants issued (in dollars per share)	$5.13	'	'	'	'	'	$12.11	'
Clinical trial expenses	80,000	329,000	'	'	'	'	'	'
Other research expenses	$474,000	'	'	'	'	'	'	'
Number of operating segments	1	'	'	'	'	'	'	'

Summary_of_Significant_Account4

Summary of Significant Accounting Policies (Details 2) (USD $)

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

In Thousands, unless otherwise specified

Convertible Preferred Stock Warrant

Money market funds

U.S. government-backed securities

Federal agency securities

Commercial paper

Corporate debt securities

Measured at fair value

Level 1

Level 2

Level 3

Total

Money market funds

U.S. government-backed securities

Federal agency securities

Commercial paper

Corporate debt securities

Convertible Preferred Stock Warrant

Money market funds

U.S. government-backed securities

Federal agency securities

Commercial paper

Corporate debt securities

Summary of Significant Accounting Policies

Investments

$22,511

$9,351

$53,511

$5,923

$9,351

$12,301

$8,249

$1,961

$53,511

$5,923

$53,511

$5,923

$22,511

$9,351

$12,301

$8,249

$1,961

$76,022

$15,274

$53,511

$5,923

$9,351

$12,301

$8,249

$1,961

Financial liabilities

$157

$117

$157

Summary_of_Significant_Account5

Summary of Significant Accounting Policies (Details 3) (Convertible Preferred Stock Warrant, Black-Scholes option pricing model, Level 3, USD $)	12 Months Ended
	Dec. 31, 2012
Convertible Preferred Stock Warrant \| Black-Scholes option pricing model \| Level 3	'
Inputs to pricing model	'
Estimated fair value of underlying common stock (in dollars per share)	$8
Time to liquidity	'2 years 9 months 18 days
Volatility (as a percent)	55.00%
Risk free interest rate (as a percent)	0.36%

Summary_of_Significant_Account6

Summary of Significant Accounting Policies (Details 4) (Convertible Preferred Stock Warrant, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Changes in financial instruments measured at fair value using Level 3 inputs	'	'
Beginning balance	$157	$117
Issuances	'	79
Reclassification to additional paid-in capital upon conversion to common stock warrant	157	'
Ending balance	'	157
Other income (expense), net	'	'
Changes in financial instruments measured at fair value using Level 3 inputs	'	'
Unrealized loss included in other income (expense), net	'	($39)

Summary_of_Significant_Account7

Summary of Significant Accounting Policies (Details 5)	12 Months Ended
Summary of Significant Accounting Policies (Details 5)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net loss per common share	'	'	'
Antidilutive securities excluded from computations of diluted net loss per common share	1,909,329	13,432,154	11,921,359
Convertible preferred stock	'	'	'
Net loss per common share	'	'	'
Antidilutive securities excluded from computations of diluted net loss per common share	'	12,329,330	10,657,030
Warrants to purchase preferred stock	'	'	'
Net loss per common share	'	'	'
Antidilutive securities excluded from computations of diluted net loss per common share	'	72,029	38,997
Warrants to purchase common stock	'	'	'
Net loss per common share	'	'	'
Antidilutive securities excluded from computations of diluted net loss per common share	88,545	'	'
Unvested common stock	'	'	'
Net loss per common share	'	'	'
Antidilutive securities excluded from computations of diluted net loss per common share	'	'	139,033
Options to purchase common stock	'	'	'
Net loss per common share	'	'	'
Antidilutive securities excluded from computations of diluted net loss per common share	1,820,784	1,030,795	1,086,299

Investments_Details

Investments (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Investments	'	'
Amortized Cost	$76,019	$15,270
Gross Unrealized Gains	3	4
Fair Value	22,511	9,351
Cash and cash equivalents	'	'
Investments	'	'
Fair Value	53,306	5,718
Marketable securities	'	'
Investments	'	'
Fair Value	22,511	9,351
Restricted cash	'	'
Investments	'	'
Fair Value	205	205
Money market funds	'	'
Investments	'	'
Amortized Cost	53,511	5,923
Fair Value	53,511	5,923
Federal agency securities	'	'
Investments	'	'
Amortized Cost	12,301	'
Fair Value	12,301	'
U.S. government-backed securities	'	'
Investments	'	'
Amortized Cost	'	9,347
Gross Unrealized Gains	'	4
Fair Value	'	9,351
Commercial paper	'	'
Investments	'	'
Amortized Cost	8,246	'
Gross Unrealized Gains	3	'
Fair Value	8,249	'
Corporate debt securities	'	'
Investments	'	'
Amortized Cost	1,961	'
Fair Value	$1,961	'

Property_and_Equipment_Details

Property and Equipment (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Property and equipment	'	'
Property and equipment, gross	$3,517	$3,174
Accumulated depreciation and amortization	-3,241	-2,944
Property and equipment, net	276	230
Laboratory equipment	'	'
Property and equipment	'	'
Property and equipment, gross	1,453	1,453
Computer equipment and software	'	'
Property and equipment	'	'
Property and equipment, gross	493	435
Leasehold improvements, furniture and fixtures	'	'
Property and equipment	'	'
Property and equipment, gross	$1,571	$1,286

Property_and_Equipment_Details1

Property and Equipment (Details 2) (USD $)	12 Months Ended
Property and Equipment (Details 2) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property and Equipment	'	'	'
Depreciation and amortization expense	$298,000	$193,000	$484,000

Research_and_Development_Colla2

Research and Development Collaboration and License Agreements (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Research and Development Collaboration and License Agreements	'	'	'
Research and development expenses	$32,640,000	$24,519,000	$18,512,000
Sanofi	'	'	'
Research and Development Collaboration and License Agreements	'	'	'
Initial upfront non-refundable payment	35,000,000	'	'
Additional non-refundable payment	5,000,000	'	'
Development, regulatory and commercial contingent payments	250,000,000	'	'
Maximum days to participate in development and promotion of products	'90 days	'	'
Upfront payment being recognized	40,000,000	'	'
Research and development expenses	$1,100,000	'	'

Research_and_Development_Colla3

Research and Development Collaboration and License Agreements (Details 2) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Contract revenue:	'	'	'	'	'	'	'	'	'	'	'
Amortization of upfront fees	'	'	'	'	'	'	'	'	'	$5,630	$18,977
Reimbursement for development-related activities	'	'	'	'	'	'	'	'	44	468	1,278
Contract revenue	$4	$9	$15	$16	$19	$69	$2,992	$3,018	$44	$6,098	$20,255

Notes_Payable_Details

Notes Payable (Details) (USD $)

Dec. 31, 2013

Sep. 30, 2012

Dec. 31, 2013

Jun. 19, 2013

Sep. 30, 2012

Dec. 31, 2013

Sep. 30, 2012

Dec. 31, 2013

Sep. 30, 2012

Dec. 31, 2013

Sep. 30, 2012

Jun. 30, 2013

Sep. 30, 2012

Loan and Security Agreement

Tranche

LIBOR variable interest rate

Prepayment through December 31, 2014

Prepayment in 2015

Prepayment in final year

Minimum

First Tranche, issued in September 2012

Second Tranche, issued in December 2012

Final tranche that may be drawn at option of Company no later than June 2013

Series E Convertible Preferred Stock

Notes payable

Maximum amount of borrowing under the agreement

$15,000,000

$5,000,000

Amount of borrowing required to be drawn

10,000,000

Amount of remaining borrowing capacity

5,000,000

Number of loan tranches

Variable rate basis

'one month LIBOR

Spread on variable rate (as a percent)

6.00%

LIBOR floor rate

3.00%

Straight-line principal payments period

'36 months

Percentage of exit fee of drawn amount

3.00%

Warrants issued as a percentage of amount drawn under credit facility

4.00%

Exercise price of warrant (in dollars per share)

$5.13

$12.11

Prepayment fee percentage

5.00%

2.00%

1.00%

Prepayment period start date

1-Jan-14

1-Jan-16

Prepayment period end date

31-Dec-14

31-Dec-15

Tranche draw down

5,000,000

Debt discount related to issuance of warrants

79,000

117,000

Debt issuance cost paid

114,000

Issuance of warrant to purchase shares of common stock

38,997

49,548

Warrants initial fair value

130,000

Interest expense related to borrowings

$1,100,000

Effective interest rate (as a percent)

10.00%

Notes_Payable_Details_2

Notes Payable (Details 2) (Loan and Security Agreement, USD $)	Dec. 31, 2013	Sep. 30, 2012
Loan and Security Agreement	'	'
Debt obligations	'	'
Variable rate of interest (as a percent)	9.00%	'
2014	$4,020,000	'
2015	3,724,000	'
2016	3,701,000	'
Total minimum payments	11,445,000	'
Less amount representing interest	-1,445,000	'
Notes payable, gross	10,000,000	'
Discount on notes payable	-117,000	-79,000
Accretion of the final exit fee payment	85,000	'
Carrying value of notes payable	$9,968,000	'

Warrants_to_Purchase_Common_St1

Warrants to Purchase Common Stock (Details) (USD $)	Dec. 31, 2013	Jun. 19, 2013	Jun. 19, 2013
		Loan and Security Agreement	Loan and Security Agreement
			Maximum
Class of Warrant or Right [Line Items]	'	'	'
Issuance of warrant to purchase shares of common stock	38,997	'	49,548
Exercise price of warrants issued (in dollars per share)	$5.13	$12.11	'

Commitments_and_Contingencies_1

Commitments and Contingencies (Details) (USD $)	1 Months Ended	12 Months Ended			1 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 31, 2009	Mar. 31, 2012	Jan. 31, 2011
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Third party one	Third party two	Standby letter of credit
Commitments and contingencies	'	'	'	'	'	'	'
Issued amount	'	'	'	'	'	'	$0.20
Deferred rent	'	'	'	0.2	'	'	'
Period after which lessee have option to terminate lease	'36 months	'	'	'	'	'	'
Term of new lease	'5 years	'	'	'	'	'	'
Additional term of new lease	'5 years	'	'	'	'	'	'
Sublease agreement, term	'	'	'	'	'29 months	'28 months	'
Rent expense, net of sublease income	'	0	0.1	0.6	'	'	'
Sublease income	'	1.1	1	0.5	'	'	'
Accruals or expenses related to indemnification issues	'	$0	'	'	'	'	'

Commitments_and_Contingencies_2

Commitments and Contingencies (Details 2) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified	item
Commitments and Contingencies	'
2014	$1,026
2015	701
2016	759
2017	818
2018	843
Total	$4,147
Number of leases	2

Commitments_and_Contingencies_3

Commitments and Contingencies (Details 3) (USD $)	Dec. 31, 2013
Sublease payments	'
2014	$553,000

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)	1 Months Ended	12 Months Ended		1 Months Ended
	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Feb. 28, 2013	Oct. 31, 2013	Dec. 31, 2013
	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	IPO	Equity public offering	Convertible Preferred stock
Stockholders' Equity	'	'	'	'	'	'
Issued during the period (in shares)	'	'	'	8,750,000	8,625,000	'
Public offering price for common stock (in dollars per share)	'	'	'	$8	$4	'
Proceeds from issuances of common stock	'	$32,430,000	'	$70,000,000	$34,500,000	'
Net proceeds from issuance of common stock	'	'	'	61,500,000	32,000,000	'
Underwriting expenses	'	'	'	8,500,000	2,500,000	'
Underwriting discounts and commissions	'	'	'	4,900,000	2,100,000	'
Other offering expenses	'	'	'	3,600,000	400,000	'
Maximum amount of securities for which the entity filed and permitted	$100,000,000	'	'	'	'	'
Shares authorized	'	0	60,152,555	'	'	0
Common Stock, shares authorized upon the completion of the IPO	'	47,500,000	80,000,000	'	'	'

Stockholders_Equity_Details_2

Stockholders' Equity (Details 2) (USD $)	1 Months Ended	12 Months Ended
Stockholders' Equity (Details 2) (USD $)	Jan. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Feb. 28, 2010
Stock-Based Compensation Plans	'	'	'	'	'
Warrants to purchase common stock	'	88,545	'	'	'
Total common stock reserved for future issuance	'	3,082,283	'	'	'
Number of shares authorized to be issued under the plan	141,795	'	'	'	153,026
Vesting period	'	'4 years	'	'	'
Vesting period expiration	'	'10 years	'	'	'
Equity Incentive Plan period	'	'10 years	'	'	'
Awards, common stock vested	56,998	'	'	'	'
Stock-based compensation expense	'	$1,440,000	$821,000	$221,000	'
Total fair value of options vested	'	1,600,000	97,000	61,000	'
Unrecognized compensation expense	'	3,000,000	'	'	'
Weighted-average period	'	'2 years 10 months 24 days	'	'	'
Total intrinsic value of stock options exercised	'	787,000	607,000	'	'
Weighted-average fair value-based measurement of stock option granted	'	$3.03	$6.98	$0.82	'
2001 stock plan	'	'	'	'	'
Stock-Based Compensation Plans	'	'	'	'	'
Options outstanding (in shares)	'	680,005	'	'	'
2001 stock plan \| Maximum	'	'	'	'	'
Stock-Based Compensation Plans	'	'	'	'	'
Number of shares authorized to be issued under the plan	'	3,408,247	'	'	'
Fair market value percentage for nonstatutory options	'	85.00%	'	'	'
2012 Equity Incentive Plan	'	'	'	'	'
Stock-Based Compensation Plans	'	'	'	'	'
Options outstanding (in shares)	'	1,140,780	'	'	'
Shares available for future grant	'	1,172,953	'	'	'
Number of shares authorized to be issued under the plan, before 2001 Plan additions	'	1,123,131	'	'	'
Vesting period	'	'4 years	'	'	'
Vesting period expiration	'	'10 years	'	'	'
Percentage of increase in the number of shares reserved for issuance	'	5.00%	'	'	'
Increase in the number of shares reserved for issuance	'	842,348	'	'	'
Fiscal year over which number of shares reserved for issuance will increase, starting year	'	'2013	'	'	'
Fiscal year over which number of shares reserved for issuance will increase, ending year	'	'2022	'	'	'
2012 Equity Incentive Plan \| Maximum	'	'	'	'	'
Stock-Based Compensation Plans	'	'	'	'	'
Carryover of shares from 2001 Plan	'	1,066,975	'	'	'
Stock Awards	'	'	'	'	'
Stock-Based Compensation Plans	'	'	'	'	'
Stock-based compensation expense	'	'	$401,000	$52,000	'

Stockholders_Equity_Details_3

Stockholders' Equity (Details 3) (USD $)	12 Months Ended
Stockholders' Equity (Details 3) (USD $)	Dec. 31, 2013
Number of Shares	'
Balance at the beginning of the period (in shares)	1,030,795
Options granted (in shares)	1,242,247
Options canceled (in shares)	-293,981
Options exercised (in shares)	-158,277
Balance at the end of the period (in shares)	1,820,784
Options vested and expected to vest at the end of the period (in shares)	1,628,820
Options exercisable (in shares)	694,144
Weighted-Average Exercise Price (Per Share)	'
Balance at the beginning of the period (in dollars per share)	$2.68
Options granted (in dollars per share)	$5.61
Options canceled (in dollars per share)	$4.90
Options exercised (in dollars per share)	$1.04
Balance at the ending of the period (in dollars per share)	$4.46
Options vested and expected to vest at the end of the period (in dollars per share)	$4.36
Options exercisable (in dollars per share)	$2.91
Weighted-Average Remaining Contractual Term (in years)	'
Balance at the end of the period	'7 years 7 months 13 days
Options vested and expected to vest at the end of the period	'7 years 5 months 5 days
Options exercisable	'5 years 2 months 1 day
Aggregate Intrinsic Value (in thousands)	'
Balance at the end of the period	$1,515
Options vested and expected to vest at the end of the period	1,493
Options exercisable	$1,366

Stockholders_Equity_Details_4

Stockholders' Equity (Details 4) (USD $)	12 Months Ended
Stockholders' Equity (Details 4) (USD $)	Dec. 31, 2013
Stock Options Outstanding	'
Number of Shares	1,820,784
Weighted Average Remaining Contractual Life	'7 years 7 months 13 days
Weighted Average Exercise Price (in dollars per share)	$4.46
Stock Options Exercisable	'
Number of Shares	694,144
Weighted Average Exercise Price Per Share (in dollars per share)	$2.91
$0.50 - $1.46	'
Stock options outstanding and exercisable by exercise price	'
Exercise Price, low end of range (in dollars per share)	$0.50
Exercise Price, high end of range (in dollars per share)	$1.46
Stock Options Outstanding	'
Number of Shares	410,600
Weighted Average Remaining Contractual Life	'4 years 2 months 26 days
Weighted Average Exercise Price (in dollars per share)	$1.12
Stock Options Exercisable	'
Number of Shares	397,640
Weighted Average Exercise Price Per Share (in dollars per share)	$1.11
$2.17 - $4.74	'
Stock options outstanding and exercisable by exercise price	'
Exercise Price, low end of range (in dollars per share)	$2.17
Exercise Price, high end of range (in dollars per share)	$4.74
Stock Options Outstanding	'
Number of Shares	481,326
Weighted Average Remaining Contractual Life	'8 years 18 days
Weighted Average Exercise Price (in dollars per share)	$4.24
Stock Options Exercisable	'
Number of Shares	149,416
Weighted Average Exercise Price Per Share (in dollars per share)	$4.36
$5.25 - $5.75	'
Stock options outstanding and exercisable by exercise price	'
Exercise Price, low end of range (in dollars per share)	$5.25
Exercise Price, high end of range (in dollars per share)	$5.75
Stock Options Outstanding	'
Number of Shares	310,000
Weighted Average Remaining Contractual Life	'8 years 11 months 16 days
Weighted Average Exercise Price (in dollars per share)	$5.64
Stock Options Exercisable	'
Number of Shares	2,222
Weighted Average Exercise Price Per Share (in dollars per share)	$5.57
$6.00	'
Stock Options Outstanding	'
Number of Shares	555,165
Weighted Average Remaining Contractual Life	'8 years 11 months 1 day
Weighted Average Exercise Price (in dollars per share)	$6
Stock Options Exercisable	'
Number of Shares	136,678
Weighted Average Exercise Price Per Share (in dollars per share)	$6
$6.42 - $11.36	'
Stock options outstanding and exercisable by exercise price	'
Exercise Price, low end of range (in dollars per share)	$6.42
Exercise Price, high end of range (in dollars per share)	$11.36
Stock Options Outstanding	'
Number of Shares	63,693
Weighted Average Remaining Contractual Life	'8 years 2 months 26 days
Weighted Average Exercise Price (in dollars per share)	$8.60
Stock Options Exercisable	'
Number of Shares	8,188
Weighted Average Exercise Price Per Share (in dollars per share)	$11.36

Stockholders_Equity_Details_5

Stockholders' Equity (Details 5)	12 Months Ended
Stockholders' Equity (Details 5)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Weighted-average fair value assumptions	'	'	'
Expected term	'6 years	'6 years	'6 years
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%
Minimum	'	'	'
Weighted-average fair value assumptions	'	'	'
Expected volatility, minimum (as a percent)	57.00%	57.00%	58.00%
Risk-free interest rate, minimum (as a percent)	0.90%	0.80%	1.90%
Maximum	'	'	'
Weighted-average fair value assumptions	'	'	'
Expected volatility, maximum (as a percent)	59.00%	59.00%	60.00%
Risk-free interest rate, maximum (as a percent)	2.10%	1.40%	2.70%

Stockholders_Equity_Details_6

Stockholders' Equity (Details 6) (USD $)	12 Months Ended
Stockholders' Equity (Details 6) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock-based compensation expense	'	'	'
Stock-based compensation expense	$1,440,000	$821,000	$221,000
General and administrative	'	'	'
Stock-based compensation expense	'	'	'
Stock-based compensation expense	731,000	423,000	93,000
Research and development	'	'	'
Stock-based compensation expense	'	'	'
Stock-based compensation expense	$709,000	$398,000	$128,000

Income_Taxes_Details

Income Taxes (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:	'	'
Net operating losses	$53,099	$37,162
Research & other credits	2,227	2,008
Other	1,447	1,030
Total deferred tax assets	56,773	40,200
Valuation allowance	-56,773	-40,200
Net deferred tax assets	$0	'

Income_Taxes_Details_2

Income Taxes (Details 2)	12 Months Ended
Income Taxes (Details 2)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of the statutory tax rates and the effective tax rates	'	'	'
Statutory rate (as a percent)	34.00%	34.00%	34.00%
Valuation allowance (as a percent)	-33.80%	-33.40%	-31.00%
Nondeductible warrant expense (as a percent)	0.00%	0.10%	0.00%
Nondeductible stock compensation (as a percent)	-0.20%	-0.60%	-2.60%
Other (as a percent)	0.00%	0.00%	-0.40%
Effective tax rate (as a percent)	0.00%	0.00%	0.00%

Income_Taxes_Details_3

Income Taxes (Details 3) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes	'	'	'
Increase in valuation allowance	$16.60	$9.20	$0.80
Federal	'	'	'
Income taxes	'	'	'
Net operating loss carryforwards	133.3	'	'
State	'	'	'
Income taxes	'	'	'
Net operating loss carryforwards	$133.30	'	'

Income_Taxes_Details_4

Income Taxes (Details 4) (Research and development, USD $)	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2013
Federal	'
Income taxes	'
Tax credit carryforwards	$2
State	'
Income taxes	'
Tax credit carryforwards	$1.90

Income_Taxes_Details_5

Income Taxes (Details 5) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of the beginning and ending amount of unrecognized tax benefits	'	'	'
Balance at the beginning of the period	$1,069	$1,025	$1,022
Additions based on tax positions related to prior year	18	39	'
Additions based on tax positions related to current year	109	5	3
Balance at the end of the period	1,196	1,069	1,025
Interest or penalties related to unrecognized tax benefits	$0	'	'

Employee_Benefit_Plan_Details

Employee Benefit Plan (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Employee Benefit Plan	'
Employer contributions	$0

Restructuring_Charges_Details

Restructuring Charges (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Activity in accrued restructuring balance	'	'
Balance at the beginning of the period	$455	'
Additions based on charges during the year	'	1,096
Deductions based on payments during the period	-455	-641
Balance at the end of the period	'	$455

Restructuring_Charges_Details_

Restructuring Charges (Details 2) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011
Restructuring charges	'
Restructuring charge	$1,096
Research and development	'
Restructuring charges	'
Restructuring charge	900
General and administrative	'
Restructuring charges	'
Restructuring charge	$200

Quarterly_Financial_Data_unaud2

Quarterly Financial Data (unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Data (unaudited)	'	'	'	'	'	'	'	'	'	'	'
Total revenue	$4	$9	$15	$16	$19	$69	$2,992	$3,018	$44	$6,098	$20,255
Loss from operations	-9,928	-11,087	-11,571	-8,323	-11,931	-8,291	-2,113	-1,147	-40,909	-23,482	-2,267
Net loss	($10,236)	($11,329)	($11,809)	($8,574)	($11,696)	($8,602)	($2,080)	($1,131)	($41,948)	($23,509)	($2,232)
Basic and diluted net loss per common share (in dollars per share)	($0.31)	($0.47)	($0.49)	($0.55)	($1.51)	($4.05)	($1.01)	($0.56)	($1.73)	($11.22)	($1.15)
Weighted average common shares outstanding used to calculate basic and diluted net loss per common share (in shares)	32,925,194	24,263,745	24,189,819	15,607,379	7,741,335	2,124,280	2,062,926	2,023,285	24,270,407	2,095,950	1,933,672