Achaogen (AKAOQ) 10-Q 11 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	1-May-15
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	AKAO
Entity Registrant Name	ACHAOGEN INC
Entity Central Index Key	1301501
Current Fiscal Year End Date	-19
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		18,049,934

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$22,933	$18,881
Short-term investments	38,713	44,798
Contracts receivable	4,472	5,234
Prepaids and other current assets	605	520
Total current assets	66,723	69,433
Property and equipment, net	648	725
Restricted cash	127	127
Deposit and other assets	47	37
Total assets	67,545	70,322
Current liabilities:
Accounts payable	3,947	2,122
Accrued liabilities	3,254	3,266
Other current liabilities	132	128
Total current liabilities	7,333	5,516
Deferred rent	160	193
Total liabilities	7,493	5,709
Commitments and contingencies
Stockholders’ equity
Common stock, $0.001 par value, 290,000,000 shares authorized at March 31, 2015 and December 31, 2014; 18,049,934 and 17,907,135 shares issued and outstanding at March 31, 2015 and December 31, 2014, respectively	18	18
Preferred stock, $0.001 par value, 10,000,000 shares authorized and zero shares issued and outstanding at March 31, 2015 and December 31, 2014	0	0
Additional paid-in-capital	215,117	213,527
Accumulated deficit	-155,079	-148,900
Accumulated other comprehensive loss	-4	-32
Total stockholders’ equity	60,052	64,613
Total liabilities and stockholders’ equity	$67,545	$70,322

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Common stock, par value per share	$0.00	$0.00
Common stock, shares authorized	290,000,000	290,000,000
Common stock, shares issued	18,049,934	17,907,135
Common stock, shares outstanding	18,049,934	17,907,135
Preferred stock, par value per share	$0.00	$0.00
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Contract revenue	$4,880	$5,988
Operating expenses
Research and development	7,879	6,605
General and administrative	3,231	2,617
Total operating expenses	11,110	9,222
Loss from operations	-6,230	-3,234
Interest expense	0	-179
Other income (expense), net	51	-42
Net loss	($6,179)	($3,455)
Basic and diluted net loss per common share	($0.34)	($1)
Weighted-average common shares outstanding used to calculate basic and diluted net loss per common share	17,998,390	3,456,088

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Loss (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net loss	($6,179)	($3,455)
Other comprehensive loss:
Net unrealized gain on available-for-sale securities	28	0
Total comprehensive loss	($6,151)	($3,455)

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net loss	($6,179)	($3,455)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	99	88
Amortization of premium on short-term investments	167	0
Stock-based compensation expense	761	367
Revaluation of convertible preferred stock warrant liability	0	42
Non-cash interest expense relating to notes payable	0	72
Change in operating assets and liabilities:
Contracts receivable	762	1,203
Prepaids and other assets	-30	1,715
Accounts payable and accrued liabilities	1,813	211
Other liabilities	-29	-1
Net cash (used in) provided by operating activities	-2,636	242
Cash flows from investing activities:
Purchase of property and equipment	-22	-7
Purchase of short-term investments	-1,997	0
Maturities of short-term investments	7,943	0
Net cash provided by (used in) investing activities	5,924	-7
Cash flows from financing activities:
Net proceeds from issuance of common stock	0	75,181
Proceeds from the exercise of stock warrants	0	2
Proceeds from the exercise of stock options, net of repurchases	764	0
Repayment of notes payable	0	-1,219
Net cash provided by financing activities	764	73,964
Net increase in cash and cash equivalents	4,052	74,199
Cash and cash equivalents, beginning of period	18,881	10,738
Cash and cash equivalents, end of period	22,933	84,937
Supplemental disclosures of noncash investing and financing information
Conversion of convertible preferred stock into common stock	0	132,278
Reclassification of warrant liability to additional paid-in-capital	0	286
Deferred initial public offering issuance costs	$0	$1,238

Organization_and_Basis_of_Pres

Organization and Basis of Presentation and Consolidation	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Organization and Basis of Presentation and Consolidation	Organization and Basis of Presentation and Consolidation
	Achaogen, Inc. (together with its consolidated subsidiary, the “Company”) is a clinical-stage biopharmaceutical company committed to the discovery, development, and commercialization of novel antibacterial drugs to treat multi-drug resistant gram-negative infections. The Company is developing plazomicin, its lead product candidate, for the treatment of bacterial infections due to Enterobacteriaceae, including carbapenem-resistant Enterobacteriaceae. The Company is running an ongoing Phase 3 CARE (Combating Antibiotic Resistant Enterobacteriaceae) trial of plazomicin and the first patients were enrolled in the trial in the third quarter of 2014. In addition, in the fourth quarter of 2015, the Company plans to commence a pivotal Phase 3 trial of plazomicin for the treatment of patients with complicated urinary tract infections.
	The Company was incorporated in Delaware in 2002 and commenced operations in 2004. Since commencing operations in 2004, the Company has devoted substantially all of its resources to identifying and developing its product candidates, including conducting preclinical studies and clinical trials and providing general and administrative support for these operations.
	Reclassifications
	Prior period's other expense amounts in the consolidated statements of operations were reclassified to conform to the current year's presentation. Such reclassification did not impact our net loss or financial position.
	Basis of Presentation and Consolidation
	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and following the requirements of the Securities and Exchange Commission (the “SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair statement of the Company’s financial information. The results of operations for the three-month period ended March 31, 2015 are not necessarily indicative of the results to be expected for the full year or any other future period. The balance sheet as of December 31, 2014 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements. Intercompany accounts and transactions have been eliminated upon consolidation.
	The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2014 included in the Company’s Annual Report on Form 10-K.
	Initial Public Offering
	In March 2014, the Company completed its initial public offering (“IPO”) of shares of its common stock, pursuant to which the Company issued 6,900,000 shares of common stock, which includes 900,000 shares issued pursuant to the over-allotment option granted to its underwriters, and received net proceeds of approximately $73.9 million, after deducting underwriting discounts, commissions and estimated offering expenses. In connection with the completion of the Company’s IPO, all shares of convertible preferred stock converted into 10,386,894 shares of common stock and all of the Company’s convertible preferred stock warrants were converted into warrants to purchase common stock.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies
	Use of Estimates
	The accompanying financial statements have been prepared in accordance with U.S. GAAP. The preparation of financial statements in conformity with U.S. GAAP requires management to make judgments, assumptions and estimates that affect the reported amounts of assets, liabilities, revenues and expenses and related disclosures of contingent liabilities. On an ongoing basis, management evaluates its estimates, including those related to clinical trial accruals, fair value of liabilities, common stock and stock-based awards and income taxes. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ materially from those estimates.
	Fair Value of Financial Instruments
	The carrying amounts of the Company’s financial instruments, including cash and cash equivalents, contracts receivable, prepaid and other current assets, accounts payable, accrued liabilities, and other current liabilities approximate fair value due to their short-term maturities. Short-term investments consist of available-for-sale securities and are carried at fair value.
	Cash and Cash Equivalents
	Cash equivalents include only securities having a maturity of three months or less at the time of purchase. As of March 31, 2015 and December 31, 2014, cash and cash equivalents consisted of bank deposits, cash, and investments in money market funds.
	Short-term Investments
	Short-term investments consist of debt securities with maturities greater than three months, but less than one year from the date of acquisition, and are classified as available for sale. Short-term investments are carried at fair value. Unrealized gains and losses on available-for-sale securities are excluded from earnings and were reported as a component of net unrealized losses on available-for-sale securities in the Company's consolidated statements of comprehensive loss. The amortized cost of debt securities reflects amortization of purchase premiums and accretion of purchase discounts to date, which is included in interest income.
	The Company reviews all of its marketable securities on a regular basis to evaluate whether any security has experienced an other-than-temporary decline in fair value.
	Restricted Cash
	At March 31, 2015 and December 31, 2014, the Company had long-term restricted cash of $127,000. The restricted cash, which consists of a money market account with one of the Company’s financial institutions, serves as collateral for a letter of credit provided as a security deposit under the Company’s facility lease. The facility lease expires on April 14, 2017.
	Segment Reporting
	Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker in making decisions regarding resource allocation and assessing performance. The Company has one operating segment.
	Customer Concentration
	For the three-month periods ended March 31, 2015 and 2014, the Company’s revenue has been generated solely from funding pursuant to U.S. government contracts, and accordingly all contracts receivable relate to funding from U.S. government contracts.
	Concentration of Credit Risk
	Financial instruments that potentially subject the Company to a significant concentration of credit risk consist of cash, cash equivalents and short-term investments. Cash and cash equivalents are deposited in checking and money market accounts at one financial institution, which at times, may exceed federally insured limits. Management believes that the financial institution is financially sound, and, accordingly, minimal credit risk exists with respect to this financial institution. Our investment policy limits investments to certain types of debt securities issued by the U.S. government, its agencies and institutions with investment-grade credit ratings and places restrictions on maturities and concentration by type and issuer. The Company is exposed to credit risk in the event of default by the institutions holding its cash and cash equivalents or issuing the debt securities. As of March 31, 2015 and December 31, 2014, the Company has not experienced any credit losses in such accounts or investments.
	Revenue Recognition
	The Company recognizes revenue when: (i) evidence of an arrangement exists, (ii) fees are fixed or determinable, (iii) services have been delivered, and (iv) collectability is reasonably assured. The Company currently generates revenue entirely from government contracts. Government contracts are agreements that provide the Company with payments for certain types of expenditures in return for research and development activities over a contractually defined period. Revenue from government contracts is recognized in the period during which the related costs are incurred and the related services are rendered, provided that the applicable conditions under the government contracts have been met.
	Funds received from third parties under contract arrangements are recorded as revenue if the Company is deemed to be the principal participant in the contract arrangements because the activities under the contracts are part of the Company’s development programs. If the Company is not the principal participant, the funds from contracts are recorded as a reduction to research and development expense. Contracts funds received are not refundable and are recognized when the related qualified research and development costs are incurred and when there is reasonable assurance that the funds will be received. Funds billed and received in advance are recorded as deferred revenue.
	Recent Accounting Pronouncements
	In January 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2015-01 “Income Statement - Extraordinary and Unusual Items (Subtopic 225-20) - Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items.” This guidance eliminates from GAAP the concept of extraordinary items and is effective for annual reporting periods, including interim reporting periods, beginning after December 15, 2015, and is applicable to the Company's fiscal year beginning January 1, 2016. Early adoption is permitted. The Company does not anticipate it will have a material impact to its consolidated financial statements.
	In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes the revenue recognition requirements in ASC 605, Revenue Recognition. This ASU is based on the principle that revenue is recognized to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The ASU also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The ASU's effective date is for interim and annual periods beginning after December 15, 2016. Adoption of the ASU is either retrospective to each prior period presented or retrospective with a cumulative adjustment to retained earnings or accumulated deficit as of the adoption date. Early adoption is not permitted. On April 1, 2015, the FASB voted to propose a one-year deferral to the effective date, but to permit entities to adopt one year earlier if they choose (i.e., the original effective date). The proposal will be subject to the FASB’s due process requirement, which includes a period for public comments. The Company is assessing the potential effects of this ASU on its consolidated financial statements.
	In August 2014, the FASB issued ASU No. 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern (Topic 205-40), Going Concern. This ASU introduces an explicit requirement for management to assess if there is substantial doubt about an entity's ability to continue as a going concern, and to provide related footnote disclosures in certain circumstances. In connection with each annual and interim period, management must assess if there is substantial doubt about an entity's ability to continue as a going concern within one year after the issuance date. Disclosures are required if conditions give rise to substantial doubt. ASU 2014-15 is effective for all entities in the first annual period ending after December 15, 2016. The Company is currently assessing the potential effects of this ASU on its consolidated financial statements.
	Net Loss Per Share
	Basic net loss per common share is computed by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per common share is computed by dividing the net loss by the weighted-average number of common shares and dilutive common share equivalents outstanding during the period. For purposes of this calculation, preferred stock, stock options and warrants are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. Because the Company has reported a net loss in all periods presented, diluted net loss per common share is the same as basic net loss per common share for those periods.
	Effective as of the completion of the IPO, all of the Company’s preferred stock was converted to common stock. For purposes of calculating net loss per common share for the three-month period ended March 31, 2014, the preferred stock converted to common stock was included in the net loss per common share calculation on a post-conversion basis based on the conversion date.
	For the three-month periods ended March 31, 2015 and 2014, all potentially dilutive securities outstanding have been excluded from the computations of diluted weighted-average shares outstanding because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares). Below are listed the potentially dilutive securities outstanding as of March 31, 2015 and 2014, respectively:
		March 31,
		2015	2014
	Options to purchase common stock	1,993,555	1,772,171
	Warrants to purchase common stock	30,024	40,454
	In March 2015, warrants to purchase 10,430 shares of common stock with an exercise price of $13.42 expired. Warrants to purchase 30,024 shares of common stock at an exercise price of $11.99 remain outstanding as of March 31, 2015.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements
	Financial assets and liabilities are recorded at fair value. The carrying amount of certain financial instruments, including cash and cash equivalents, contracts receivable, accounts payable and accrued liabilities approximate fair value due to their relatively short maturities. Assets and liabilities recorded at fair value on a recurring basis in the consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows:
	Level 1: Quoted prices in active markets for identical assets or liabilities.
	Level 2: Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
	Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability.
	Where quoted prices are available in an active market, securities are classified as Level 1 of the valuation hierarchy. The Company’s Level 2 valuations of marketable securities are generally derived from independent pricing services based upon quoted prices in active markets for similar securities, with prices adjusted for yield and number of days to maturity, or based on industry models using data inputs, such as interest rates and prices that can be directly observed or corroborated in active markets.
	In certain cases where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3 within the valuation hierarchy. Level 3 liabilities that are measured at estimated fair value on a recurring basis consist of convertible preferred stock warrant liabilities and derivative liabilities associated with certain convertible loans.
	As of March 31, 2015 and December 31 2014, financial assets and liabilities measured and recognized at fair value on a recurring basis and classified under the appropriate level of the fair value hierarchy as described above were as follows (in thousands):
		31-Mar-15
		Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	Assets
	Cash	$	977	$	—	$	—		$	977
	Level 1:
	Restricted cash	127		—		—			127
	Money market funds	21,956		—		—			21,956
	Subtotal	22,083		—		—			22,083
	Level 2:
	Corporate debt securities	36,719		4		(8		)	36,715
	Commercial paper	1,998		—		—			1,998
	Subtotal	38,717		4		(8		)	38,713
		$	61,777	$	4	$	(8	)	$	61,773
	Reported as:
	Cash and cash equivalents								$	22,933
	Short-term investments								$	38,713
	Restricted cash								$	127
		December 31, 2014
		Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	Assets
	Cash	$	620	$	—	$	—		$	620
	Level 1:
	Restricted cash	127		—		—			127
	Money market funds	18,261		—		—			18,261
	Subtotal	18,388		—		—			18,388
	Level 2:
	Corporate debt securities	44,830		—		(32		)	44,798
		$	63,838	$	—	$	(32	)	$	63,806
	Reported as:
	Cash and cash equivalents								$	18,881
	Short-term investments								$	44,798
	Restricted cash								$	127
	All available-for-sale securities held as of March 31, 2015 had maturities greater than three months, but less than one year from the date of acquisition. There were no sales of available-for-sale securities in any of the periods presented. The carrying value of corporate debt obligations that were in unrealized loss positions totaled $21.4 million as of March 31, 2015. The Company has determined that (i) it does not have the intent to sell any of these investments, and (ii) it is not more likely than not that it will be required to sell any of these investments before recovery of the entire amortized cost basis. The Company anticipates that it will recover the entire amortized cost basis of such corporate debt obligations and has determined that no other-than-temporary impairments associated with credit losses were required to be recognized during the three months ended March 31, 2015.
	In connection with the completion of the Company’s IPO in March 2014, all of the outstanding warrants to purchase convertible preferred stock converted into warrants to purchase 40,454 shares of common stock at an average exercise price of $12.36 per share. The Company remeasured the estimated fair value of these remaining warrants at the date of the conversion and recorded a $42,000 loss related to the change in estimated fair value as part of interest expense and other, net, and reclassified the estimated fair value of $286,000 to additional paid-in capital.

Balance_Sheet_Components

Balance Sheet Components	3 Months Ended
	Mar. 31, 2015
Payables and Accruals [Abstract]
Balance Sheet Components	Balance Sheet Components
	Accrued Liabilities
	Accrued liabilities consisted of the following (in thousands):
		March 31,		December 31,
		2015		2014
	Accrued clinical and development expenses	$	1,717	$	1,618
	Payroll and related bonus expenses	1,050		1,171
	Other	487		477
		$	3,254	$	3,266

License_and_Collaboration_Agre

License and Collaboration Agreements	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
License and Collaboration Agreements	License and Collaboration Agreements
	Isis Pharmaceuticals
	In January 2006, the Company entered into a license agreement with Isis Pharmaceuticals, Inc. (“Isis”). Isis granted the Company an exclusive, worldwide license with the right to grant and authorize sublicenses related to the research and development of aminoglycoside products. As an up-front fee, the Company issued 97,402 shares of Series A convertible preferred stock at a fair value of $15.40 per share. This license fee of $1,500,000 was recorded as research and development expense in 2006. In further consideration of this license, and in accordance with the terms of the agreement, the Company is required to make milestone payments with respect to development, regulatory and commercialization milestones, and to pay a percentage of revenue received from sublicensees (if any). All such milestone and sublicense revenue payments may total, in the aggregate, up to but no more than $19,500,000 for the first product and $9,750,000 following the second product commercialized under the agreement with Isis. The Company is also required to pay additional milestone payments of up to $20,000,000 in the aggregate upon the first achievement of specified threshold levels of annual net sales of all aminoglycoside products in a calendar year. The license agreement also provides that the Company shall pay royalties equal to a low single-digit percentage of annual worldwide net sales of all licensed products, including plazomicin.
	Through March 31, 2015, the Company has compensated Isis $7,000,000 in connection with the first three milestones under the license for the first aminoglycoside product candidate. As of March 31, 2015 and December 31, 2014, the Company had no outstanding payments due under the agreement.

Government_Contracts

Government Contracts	3 Months Ended
	Mar. 31, 2015
Contractors [Abstract]
Government Contracts	Government Contracts
	Certain of the Company’s drug discovery and development activities are performed under contracts with U.S. government agencies. Management has determined that the Company is the principal participant in the following contract arrangements, and, accordingly, the Company records amounts earned under the arrangements as revenue. Costs incurred under revenue contracts are recorded as operating expenses in the Company's consolidated statements of operations.
	Biomedical Advanced Research and Development Authority
	In August 2010, the Company was awarded a contract with the Biomedical Advanced Research and Development Authority (“BARDA”) for the development, manufacturing, nonclinical and clinical evaluation of, and regulatory filings for, plazomicin as a countermeasure for disease caused by antibiotic-resistant pathogens and biothreats. The original contract included committed funding of $27,600,000 for the first two years of the contract and subsequent options exercisable by BARDA to provide additional funding. In September 2012, BARDA modified the contract to increase the total contract committed funding to $43,398,000 through March 2014. In April 2013, the Company was awarded an additional $60,410,000 under the contract to support its Phase 3 clinical trial of plazomicin to increase the total committed funding under this contract to $103,808,000. The Company recorded revenues of $4,841,000 and $5,988,000 under this agreement during the three-month periods ended March 31, 2015 and 2014, respectively.
	Defense Threat Reduction Agency
	In November 2012, the Defense Threat Reduction Agency (“DTRA”) terminated for convenience a contract with the Company that provided funding for the Company’s LpxC inhibitor program. In connection with the termination, the Company was seeking payment from DTRA for additional expenses the Company has incurred. In connection with the Company’s claim for payment from DTRA, the Defense Contract Audit Agency has audited the expenses for which the Company is seeking payment. On April 30, 2015, the Company reached a settlement of its claim with DTRA, see Note 9, Subsequent Event.
	National Institute of Allergy and Infectious Diseases
	In July 2014, the Company was awarded a one-year, $407,000 grant by the National Institute of Allergy and Infectious Diseases (NIAID) to conduct discovery research on novel antibiotics targeting gram-negative bacteria. The Company recorded revenues of $39,000 and zero under this grant during the three-month periods ended March 31, 2015 and 2014, respectively.

Borrowings

Borrowings	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Borrowings	Borrowings
	Oxford Finance and SVB Loan Agreement
	In November 2011, the Company entered into a loan and security agreement (the “Loan Agreement”) with Oxford Finance LLC and Silicon Valley Bank (“SVB”), under which the Company borrowed $4,000,000 in November 2011, and the remaining $8,000,000 in April 2012. The loan principal balance, accrued interest and the final payment under the Loan Agreement totaling $4,454,000 were repaid in full in June 2014.
	During 2012 and 2011, in connection with the Loan Agreement, the Company issued warrants to Oxford Finance LLC and SVB to purchase 20,016 and 10,008 shares, respectively, of its Series C convertible preferred stock at an exercise price of $11.99 per share. The estimated fair value of these warrants at the date of issuance was approximately $163,000 and $86,000, respectively, and was recorded as a debt discount and was amortized as interest expense over the term of the loan using the effective-interest method, with the remaining balance charged to interest expense upon loan repayment.
	Immediately prior to the closing of the IPO, these warrants automatically converted into warrants exercisable for shares of common stock, resulting in the reclassification of the related preferred stock warrant liabilities to additional paid-in capital. As of December 31, 2014, these warrants remained outstanding and exercisable.
	The Company recorded interest expense related to the loan of zero and $162,000 for the three-month periods ended March 31, 2015 and 2014, respectively.

Equity_Incentive_Plans

Equity Incentive Plans	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Incentive Plans	Equity Incentive Plans
	2014 Plan
	In February 2014, the Company’s stockholders approved the 2014 Equity Incentive Award Plan (the "2014 Plan"), which became effective as of March 11, 2014. Under the 2014 Plan, the Company may grant incentive stock options ("ISOs"), nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock units awards ("RSUs") and other stock-based awards for the purchase of that number of shares of common stock. Effective, January 1, 2015, the compensation committee of the board of directors approved an evergreen increase of 716,285 shares that may be granted in accordance with the terms of the 2014 Plan. As of March 31, 2015, 864,673 shares were available for future issuance under the 2014 Plan.
	Under the 2014 Plan, the terms of stock award agreements, including vesting requirements, are determined by the board of directors, subject to the provisions of the 2014 Plan. Options granted by the Company typically vest over a four year period and the exercise price may not be less than fair market value on the date of grant. Certain of the options are subject to acceleration of vesting in the event of certain change of control transactions. Options granted under the 2014 Plan expire no later than 10 years from the date of grant.
	2014 Employment Commencement Incentive Plan
	In December 2014, the Company adopted a 2014 Employment Commencement Incentive Plan (the "Inducement Plan"). The Inducement Plan is designed to comply with the inducement exemption contained in Nasdaq’s Rule 5635(c)(4), which provides for the grant of non-qualified stock options, restricted stock units, restricted stock awards, performance awards, dividend equivalents, deferred stock awards, deferred stock units, stock payment and stock appreciation rights to a person not previously an employee or director of the Company, or following a bona fide period of non-employment, as an inducement material to the individual’s entering into employment with the Company. The number of shares of common stock initially reserved for issuance under the Inducement Plan was 650,000 shares. As of March 31, 2015, there were no awards issued under the Inducement Plan.
	2014 Employee Stock Purchase Plan
	In February 2014, the Company’s stockholders approved the 2014 Employee Stock Purchase Plan (the “ESPP”), which became effective as of March 11, 2014. Effective, January 1, 2015, the board of directors approved an evergreen increase of 179,071 shares that may be granted in accordance with the terms of the ESPP. As of March 31, 2015, 17,795 shares of common stock have been issued to employees participating in the ESPP, and 306,730 shares are available for issuance under the ESPP.
	Amended and Restated 2003 Stock Plan
	The Company’s Amended and Restated 2003 Stock Plan, referred to herein as the 2003 Plan, provided for the granting of incentive and non-statutory stock options to employees, directors and consultants at the discretion of the board of directors. The Company granted options under its 2003 Plan until January 2014 when it was terminated as to future awards, although it continues to govern the terms of options that remain outstanding under the 2003 Plan.
	Options granted under the 2003 Plan expire no later than 10 years from the date of grant. Options granted under the 2003 Plan vest over periods determined by the board of directors, generally over four years. The board of directors determined the fair value of common stock at the date of grant.
	The 2003 Plan allows for early exercise of certain options prior to vesting. Upon termination of employment, the unvested shares are subject to repurchase at the original exercise price. Stock options granted or modified after March 21, 2002, that are subsequently exercised for cash prior to vesting, are not deemed to be issued until those shares vest. As of December 31, 2014 and 2013 there were no shares subject to repurchase relating to the early exercise of options.
	In connection with the Board of Directors and stockholders approval of the 2014 Equity Incentive Award Plan (the “2014 Plan”), all remaining shares available for future awards under the 2003 Plan were transferred to the 2014 Plan, and the 2003 Plan was terminated as to future awards. As of March 31, 2015, a total of 1,055,799 shares of common stock are subject to options outstanding under the 2003 plan, which shares will become available under the 2014 Plan to the extent the options are forfeited or lapse unexercised.
	The following table summarizes stock option activity under the stock plans and related information:
		Shares			Shares			Weighted-			Weighted-
		Available			Subject to			Average			Average
		for Grant			Options			Exercise			Remaining
					Outstanding			Price			Contractual
											Term
											(years)
	Balance at December 31, 2014	1,111,470			1,885,372			$	7.95		7.62
	Additional shares authorized	716,285			—
	Options granted	(320,200	)		320,200			$	10.99
	Options exercised	—			(142,799	)		$	5.8
	Options cancelled	69,218			(69,218	)		$	8.43
	RSUs granted	(75,200	)		—
	RSUs cancelled	13,100			—
	Balance at March 31, 2015	1,514,673			1,993,555			$	8.57		8.23
	Stock-based compensation expense recognized for stock options granted to employees and non-employee directors in the Company’s condensed consolidated statements of operations was as follows (in thousands):
		Three-Month Periods
		Ended March 31,
		2015				2014
	Research and development	$	312			$	151
	General and administrative	449				216
	Total	$	761			$	367
	As of March 31, 2015, approximately $6,360,000 of total unrecognized stock-based compensation expense related to unvested stock options is expected to be recognized over a weighted-average period of 3.32 years.
	The estimated grant date fair value of employee stock options was calculated using the Black-Scholes valuation model, based on the following assumptions:
		Three Months Ended
		March 31,
		2015		2014
	Expected term (years)	6.0 years		5.3–6.1 years
	Expected volatility	70%		76%–77%
	Risk-free interest rate	1.5%–1.8%		1.7%–1.9%
	Expected dividend yield	—		—
	Expected forfeiture rate	8.30%		7.80%
	Restricted Stock Units Granted to Employees
	During the three months ended March 31, 2015, the Company granted RSUs to employees to receive 75,200 shares of common stock under the stock plans with a weighted-average estimated grant-date fair value of $11.02 per share. RSUs generally vest annually over a 4-year service period and vesting is contingent on continued service. As of March 31, 2015, there were unrecognized compensation costs of $2,081,000 related to outstanding RSUs, which are expected to be recognized over a weighted-average period of 3.65 years.
	A summary of RSU activity is as follows:
		RSU Awards Outstanding
		Number of RSUs			Weighted-Average Grant Date Fair Market Value				Aggregate Intrinsic Value
									(in thousands)
	Balance, December 31, 2014	168,200			$	9.33			$	2,195
	RSUs granted	75,200			$	11.02
	RSUs cancelled	(13,100	)		$	11.17
	Balance, March 31, 2015	230,300			$	9.78			$	2,248

Subsequent_Event

Subsequent Event	3 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event
	Effective April 30, 2015, the Company entered into a settlement of its claim with DTRA, a division of the U.S. Department of Defense. The net settlement of $7.1 million payable to the Company, together with sums previously received and entry into the settlement, constitutes payment in full and complete settlement of the amount due to the Company for the complete termination of the contract.

Organization_and_Basis_of_Pres1

Organization and Basis of Presentation and Consolidation (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation
	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and following the requirements of the Securities and Exchange Commission (the “SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair statement of the Company’s financial information. The results of operations for the three-month period ended March 31, 2015 are not necessarily indicative of the results to be expected for the full year or any other future period. The balance sheet as of December 31, 2014 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements. Intercompany accounts and transactions have been eliminated upon consolidation.
	The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2014 included in the Company’s Annual Report on Form 10-K.
Initial Public Offering	Initial Public Offering
	In March 2014, the Company completed its initial public offering (“IPO”) of shares of its common stock, pursuant to which the Company issued 6,900,000 shares of common stock, which includes 900,000 shares issued pursuant to the over-allotment option granted to its underwriters, and received net proceeds of approximately $73.9 million, after deducting underwriting discounts, commissions and estimated offering expenses. In connection with the completion of the Company’s IPO, all shares of convertible preferred stock converted into 10,386,894 shares of common stock and all of the Company’s convertible preferred stock warrants were converted into warrants to purchase common stock.
Use of Estimates	Use of Estimates
	The accompanying financial statements have been prepared in accordance with U.S. GAAP. The preparation of financial statements in conformity with U.S. GAAP requires management to make judgments, assumptions and estimates that affect the reported amounts of assets, liabilities, revenues and expenses and related disclosures of contingent liabilities. On an ongoing basis, management evaluates its estimates, including those related to clinical trial accruals, fair value of liabilities, common stock and stock-based awards and income taxes. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ materially from those estimates.
Fair Value of Financial Instruments	Fair Value of Financial Instruments
	The carrying amounts of the Company’s financial instruments, including cash and cash equivalents, contracts receivable, prepaid and other current assets, accounts payable, accrued liabilities, and other current liabilities approximate fair value due to their short-term maturities. Short-term investments consist of available-for-sale securities and are carried at fair value.
Cash and Cash Equivalents	Cash and Cash Equivalents
	Cash equivalents include only securities having a maturity of three months or less at the time of purchase.
Short-term Investments	Short-term Investments
	Short-term investments consist of debt securities with maturities greater than three months, but less than one year from the date of acquisition, and are classified as available for sale. Short-term investments are carried at fair value. Unrealized gains and losses on available-for-sale securities are excluded from earnings and were reported as a component of net unrealized losses on available-for-sale securities in the Company's consolidated statements of comprehensive loss. The amortized cost of debt securities reflects amortization of purchase premiums and accretion of purchase discounts to date, which is included in interest income.
	The Company reviews all of its marketable securities on a regular basis to evaluate whether any security has experienced an other-than-temporary decline in fair value.
Restricted Cash	Restricted Cash
	At March 31, 2015 and December 31, 2014, the Company had long-term restricted cash of $127,000. The restricted cash, which consists of a money market account with one of the Company’s financial institutions, serves as collateral for a letter of credit provided as a security deposit under the Company’s facility lease. The facility lease expires on April 14, 2017.
Segment Reporting	Segment Reporting
	Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker in making decisions regarding resource allocation and assessing performance. The Company has one operating segment.
Customer Concentration	Customer Concentration
	For the three-month periods ended March 31, 2015 and 2014, the Company’s revenue has been generated solely from funding pursuant to U.S. government contracts, and accordingly all contracts receivable relate to funding from U.S. government contracts.
Revenue Recognition	Revenue Recognition
	The Company recognizes revenue when: (i) evidence of an arrangement exists, (ii) fees are fixed or determinable, (iii) services have been delivered, and (iv) collectability is reasonably assured. The Company currently generates revenue entirely from government contracts. Government contracts are agreements that provide the Company with payments for certain types of expenditures in return for research and development activities over a contractually defined period. Revenue from government contracts is recognized in the period during which the related costs are incurred and the related services are rendered, provided that the applicable conditions under the government contracts have been met.
	Funds received from third parties under contract arrangements are recorded as revenue if the Company is deemed to be the principal participant in the contract arrangements because the activities under the contracts are part of the Company’s development programs. If the Company is not the principal participant, the funds from contracts are recorded as a reduction to research and development expense. Contracts funds received are not refundable and are recognized when the related qualified research and development costs are incurred and when there is reasonable assurance that the funds will be received. Funds billed and received in advance are recorded as deferred revenue.
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	In January 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2015-01 “Income Statement - Extraordinary and Unusual Items (Subtopic 225-20) - Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items.” This guidance eliminates from GAAP the concept of extraordinary items and is effective for annual reporting periods, including interim reporting periods, beginning after December 15, 2015, and is applicable to the Company's fiscal year beginning January 1, 2016. Early adoption is permitted. The Company does not anticipate it will have a material impact to its consolidated financial statements.
Net Loss Per Share	Net Loss Per Share
	Basic net loss per common share is computed by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per common share is computed by dividing the net loss by the weighted-average number of common shares and dilutive common share equivalents outstanding during the period. For purposes of this calculation, preferred stock, stock options and warrants are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. Because the Company has reported a net loss in all periods presented, diluted net loss per common share is the same as basic net loss per common share for those periods.
	Effective as of the completion of the IPO, all of the Company’s preferred stock was converted to common stock. For purposes of calculating net loss per common share for the three-month period ended March 31, 2014, the preferred stock converted to common stock was included in the net loss per common share calculation on a post-conversion basis based on the conversion date.
	For the three-month periods ended March 31, 2015 and 2014, all potentially dilutive securities outstanding have been excluded from the computations of diluted weighted-average shares outstanding because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares). Below are listed the potentially dilutive securities outstanding as of March 31, 2015 and 2014, respectively:
		March 31,
		2015	2014
	Options to purchase common stock	1,993,555	1,772,171
	Warrants to purchase common stock	30,024	40,454

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Schedule of Potentially Dilutive Securities Outstanding Excluded from the Computations of Diluted Weighted-Average Shares Outstanding	Below are listed the potentially dilutive securities outstanding as of March 31, 2015 and 2014, respectively:
		March 31,
		2015	2014
	Options to purchase common stock	1,993,555	1,772,171
	Warrants to purchase common stock	30,024	40,454

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Measured and Recognized at Fair Value	As of March 31, 2015 and December 31 2014, financial assets and liabilities measured and recognized at fair value on a recurring basis and classified under the appropriate level of the fair value hierarchy as described above were as follows (in thousands):
		31-Mar-15
		Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	Assets
	Cash	$	977	$	—	$	—		$	977
	Level 1:
	Restricted cash	127		—		—			127
	Money market funds	21,956		—		—			21,956
	Subtotal	22,083		—		—			22,083
	Level 2:
	Corporate debt securities	36,719		4		(8		)	36,715
	Commercial paper	1,998		—		—			1,998
	Subtotal	38,717		4		(8		)	38,713
		$	61,777	$	4	$	(8	)	$	61,773
	Reported as:
	Cash and cash equivalents								$	22,933
	Short-term investments								$	38,713
	Restricted cash								$	127
		December 31, 2014
		Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	Assets
	Cash	$	620	$	—	$	—		$	620
	Level 1:
	Restricted cash	127		—		—			127
	Money market funds	18,261		—		—			18,261
	Subtotal	18,388		—		—			18,388
	Level 2:
	Corporate debt securities	44,830		—		(32		)	44,798
		$	63,838	$	—	$	(32	)	$	63,806
	Reported as:
	Cash and cash equivalents								$	18,881
	Short-term investments								$	44,798
	Restricted cash								$	127

Balance_Sheet_Components_Table

Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2015
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following (in thousands):
		March 31,		December 31,
		2015		2014
	Accrued clinical and development expenses	$	1,717	$	1,618
	Payroll and related bonus expenses	1,050		1,171
	Other	487		477
		$	3,254	$	3,266

Equity_Incentive_Plans_Tables

Equity Incentive Plans (Tables)	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock Option Activity	The following table summarizes stock option activity under the stock plans and related information:
		Shares			Shares			Weighted-			Weighted-
		Available			Subject to			Average			Average
		for Grant			Options			Exercise			Remaining
					Outstanding			Price			Contractual
											Term
											(years)
	Balance at December 31, 2014	1,111,470			1,885,372			$	7.95		7.62
	Additional shares authorized	716,285			—
	Options granted	(320,200	)		320,200			$	10.99
	Options exercised	—			(142,799	)		$	5.8
	Options cancelled	69,218			(69,218	)		$	8.43
	RSUs granted	(75,200	)		—
	RSUs cancelled	13,100			—
	Balance at March 31, 2015	1,514,673			1,993,555			$	8.57		8.23
Schedule of Stock-based Compensation Expense for Stock Options Granted to Employees and Non-employees	Stock-based compensation expense recognized for stock options granted to employees and non-employee directors in the Company’s condensed consolidated statements of operations was as follows (in thousands):
		Three-Month Periods
		Ended March 31,
		2015				2014
	Research and development	$	312			$	151
	General and administrative	449				216
	Total	$	761			$	367
Schedule of Estimated Grant Date Fair Value of Employee Stock Options Using Black-Scholes Valuation Model	The estimated grant date fair value of employee stock options was calculated using the Black-Scholes valuation model, based on the following assumptions:
		Three Months Ended
		March 31,
		2015		2014
	Expected term (years)	6.0 years		5.3–6.1 years
	Expected volatility	70%		76%–77%
	Risk-free interest rate	1.5%–1.8%		1.7%–1.9%
	Expected dividend yield	—		—
	Expected forfeiture rate	8.30%		7.80%
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	A summary of RSU activity is as follows:
		RSU Awards Outstanding
		Number of RSUs			Weighted-Average Grant Date Fair Market Value				Aggregate Intrinsic Value
									(in thousands)
	Balance, December 31, 2014	168,200			$	9.33			$	2,195
	RSUs granted	75,200			$	11.02
	RSUs cancelled	(13,100	)		$	11.17
	Balance, March 31, 2015	230,300			$	9.78			$	2,248

Organization_and_Basis_of_Pres2

Organization and Basis of Presentation and Consolidation - Additional Information (Detail) (USD $)	1 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Initial public offering, share issued	6,900,000
Shares issued for underwriters' granted of their over-allotment option	900,000
Net proceeds from initial public offering	$73.90
Preferred shares converted	10,386,894

Summary_of_Significant_Account2

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
	Segment
Accounting Policies [Abstract]
Restricted cash	$127	$127
Facility lease expiration date	14-Apr-17
Number of operating segments	1
Number of warrants expired	10,430
Exercise price of warrants expired (dollars per share)	$13.42
Warrants to purchase common stock	30,024
Warrants to purchase common stock, exercise price (in dollars per share)	$11.99

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Outstanding Excluded from the Computations of Diluted Weighted-Average Shares Outstanding (Detail)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding	1,993,555	1,772,171
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding	30,024	40,454

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants to purchase common stock	30,024
Warrants to purchase common stock, exercise price (in dollars per share)	$11.99
Reclassification of warrant liability to additional paid-in-capital	$0	$286,000
Corporate Debt Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized loss position	21,400,000
Warrants to Purchase Common Stock [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants to purchase common stock		40,454
Warrants to purchase common stock, exercise price (in dollars per share)		$12.36
Convertible Preferred Stock Warrant Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Increase in estimated fair value recognized in net loss		42,000
Reclassification of warrant liability to additional paid-in-capital		$286,000

Fair_Value_Measurements_Financ

Fair Value Measurements - Financial Assets and Liabilities Measured and Recognized at Fair Value (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash	$127	$127
Cash and cash equivalents	22,933	18,881	84,937	10,738
Short-term investments	38,713	44,798
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash	977	620
Unrealized Gains	4	0
Unrealized Losses	-8	-32
Cash and Cash Equivalents, Restricted Cash Noncurrent, and Available-for-Sale Securities, Amortized Cost Basis	61,777	63,838
Cash and Cash Equivalents, Restricted Cash Noncurrent, and Available-for-Sale Securities	61,773	63,806
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash	127	127
Money market funds	21,956	18,261
Cash and Cash Equivalents, Restricted Cash	22,083	18,388
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	38,717
Unrealized Gains	4
Unrealized Losses	-8
Available-for-sale Securities	38,713
Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	36,719	44,830
Unrealized Gains	4
Unrealized Losses	-8	-32
Available-for-sale Securities	36,715	44,798
Commercial Paper [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	1,998
Available-for-sale Securities	$1,998

Balance_Sheet_Components_Sched

Balance Sheet Components - Schedule of Accrued Liabilities (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Payables and Accruals [Abstract]
Accrued clinical and development expenses	$1,717	$1,618
Payroll and related bonus expenses	1,050	1,171
Other	487	477
Accrued liabilities	$3,254	$3,266

License_and_Collaboration_Agre1

License and Collaboration Agreements - Additional Information (Detail) (USD $)	3 Months Ended		1 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Jan. 31, 2006	Dec. 31, 2014
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expense	$7,879,000	$6,605,000
Isis Pharmaceuticals License Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments for first commercialization product			19,500,000
Milestone payments for second commercialization product			9,750,000
Aggregate additional milestone payments			20,000,000
Cumulative milestones compensation	7,000,000
Milestone payments due	0			0
Isis Pharmaceuticals License Agreement [Member] | Up-front License Fee [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expense			$1,500,000
Isis Pharmaceuticals License Agreement [Member] | Up-front License Fee [Member] | Series A Convertible Preferred Stock [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Shares, Issued			97,402
Shares issued price per share			$15.40

Government_Contracts_Additiona

Government Contracts - Additional Information (Detail) (USD $)	1 Months Ended			3 Months Ended		1 Months Ended
	Apr. 30, 2013	Sep. 30, 2012	Aug. 31, 2010	Mar. 31, 2015	Mar. 31, 2014	Jul. 31, 2014	Dec. 31, 2014
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Contracts receivable				$4,472,000			$5,234,000
Biomedical Advanced Research and Development Authority [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development contract	103,808,000	43,398,000	27,600,000
Term of agreement			2 years
Expiration date		2014-03
Increase in research and development contract	60,410,000
Contracts revenue				4,841,000	5,988,000
National Institute for Allergy and Infectious Diseases [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development contract						407,000
Term of agreement						1 year
Contracts revenue				$39,000	$0

Borrowings_Additional_Informat

Borrowings - Additional Information (Detail) (USD $)	3 Months Ended		1 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Apr. 30, 2012	Nov. 30, 2011	Jun. 30, 2014	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Repayments of Notes Payable	$0	$1,219,000
Warrants to purchase shares of stock, shares	30,024
Warrants to purchase shares of stock, shares, exercise price per share	$11.99
Interest expense on debt	0	72,000
Oxford Finance LLC and SVB [Member]
Debt Instrument [Line Items]
Loan borrowed			8,000,000	4,000,000
Interest expense on debt	0	162,000
Loans maturity	2014-06
Oxford Finance LLC and SVB [Member] | Warrants To Purchase Series C Convertible Preferred Stock [Member]
Debt Instrument [Line Items]
Warrants to purchase shares of stock, shares						20,016	10,008
Warrants to purchase shares of stock, shares, exercise price per share						$11.99	$11.99
Fair value of warrants						163,000	86,000
Oxford Finance Corporation And Silicon Valley Bank Loan Payable [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Repayments of Notes Payable					$4,454,000

Equity_Incentive_Plans_Additio

Equity Incentive Plans - Additional Information (Detail) (USD $)	3 Months Ended	0 Months Ended	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Jan. 01, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant, additional shares authorized	716,285
Outstanding shares available for future issuance	1,514,673		1,111,470
Unrecognized stock-based compensation	$6,360
Weighted-average period of cost expected to be recognized	3 years 3 months 25 days
Stock Incentive Plan 2003 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option expiration period	10 years
Vesting period	4 years
Shares of common stock subject to options outstanding	1,055,799
2014 Equity Incentive Award Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant, additional shares authorized		716,285
Outstanding shares available for future issuance	864,673
Option expiration period	10 years
Vesting period	4 years
2014 Employment Commencement Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding shares available for future issuance			650,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant, additional shares authorized		179,071
Outstanding shares available for future issuance	306,730
Common stock, shares issued			17,795
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Weighted-average period of cost expected to be recognized	3 years 7 months 25 days
Weighted-average grant date fair market value, shares granted	$11.02
Shares granted	75,200
Unrecognized share-based compensation expense	$2,081

Equity_Incentive_Plans_Summary

Equity Incentive Plans - Summary of Stock Option Activity (Detail) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Available for Grant, Beginning balance	1,111,470
Shares Available for Grant, Additional shares authorized	716,285
Shares Available for Grant, Options granted	-320,200
Shares Available for Grant, Options exercised	0
Shares Available for Grant, Options cancelled	69,218
Shares Available for Grant, Ending balance	1,514,673	1,111,470
Shares Subject to Options Outstanding, Beginning balance	1,885,372
Shares Subject to Options Outstanding, Options granted	320,200
Shares Subject to Options Outstanding, Options exercised	-142,799
Shares Subject to Options Outstanding, Options cancelled	-69,218
Shares Subject to Options Outstanding, Ending balance	1,993,555	1,885,372
Weighted-Average Exercise Price, Beginning balance	$7.95
Weighted-Average Exercise Price, Options granted	$10.99
Weighted-Average Exercise Price, Options exercised	$5.80
Weighted-Average Exercise Price, Options cancelled	$8.43
Weighted-Average Exercise Price, Ending balance	$8.57	$7.95
Weighted-Average Remaining Contractual Term, balance	8 years 2 months 23 days	7 years 7 months 14 days
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	-75,200
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	13,100

Equity_Incentive_Plans_Schedul

Equity Incentive Plans - Schedule of Stock-Based Compensation Expense for Stock Options Granted to Employees and Non-Employees (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$761	$367
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	312	151
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$449	$216

Equity_Incentive_Plans_Schedul1

Equity Incentive Plans - Schedule of Estimated Grant Date Fair Value of Employee Stock Options Using Black-Scholes Valuation Model (Detail)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected term (years)	6 years
Expected volatility	70.00%
Expected volatility, minimum		76.00%
Expected volatility, maximum		77.00%
Risk-free interest rate, minimum	1.50%	1.70%
Risk-free interest rate, maximum	1.80%	1.90%
Expected dividend yield	0.00%	0.00%
Expected forfeiture rate	8.30%	7.80%
Minimum [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected term (years)		5 years 3 months 20 days
Maximum [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected term (years)		6 years 1 month 6 days

Equity_Incentive_Plans_Summary1

Equity Incentive Plans - Summary of Restricted Stock Activity (Details) (Restricted Stock Units (RSUs) [Member], USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Outstanding, Beginning balance	168,200
Shares granted	75,200
Shares cancelled	-13,100
Shares Outstanding, Ending balance	230,300
Weighted-Average Grant Date Fair Market Value, Beginning balance	$9.33
Weighted-Average Grant Date Fair Market Value, Shares granted	$11.02
Weighted-Average Grant Date Fair Value, shares cancelled	$11.17
Weighted-Average Grant Date Fair Market Value, Ending balance	$9.78
Aggregate intrinsic Value, Beginning balance	$2,195
Aggregate intrinsic Value, Ending balance	$2,248

Subsequent_Event_Details

Subsequent Event (Details) (Defense Threat Reduction Agency [Member], Subsequent Event [Member], USD $)	Apr. 30, 2015
In Millions, unless otherwise specified
Defense Threat Reduction Agency [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Contract settlement receivable	$7.10