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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2015	Oct. 31, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q3
Trading Symbol	CBYL
Entity Registrant Name	CARBYLAN THERAPEUTICS, INC.
Entity Central Index Key	0001348911
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		26,322,494

Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 59,878	$ 3,897
Prepaid expenses and other current assets	1,571	690
Total current assets	61,449	4,587
Property and equipment, net	362	180
Restricted cash	50	50
Deferred public offering costs		1,648
Other assets	218	179
Total assets	62,079	6,644
Current liabilities:
Accounts payable	1,527	1,024
Accrued expenses	1,272	1,605
Loans payable	965	4,435
Deferred licensing revenue	29	29
Total current liabilities	3,793	7,093
Loans payable, net of current portion	3,601
Convertible promissory notes		2,131
Derivative liability		1,495
Preferred stock warrant liability		463
Deferred licensing revenue, net of current portion	64	85
Deferred rent, net of current portion		2
Total liabilities	7,458	11,269
Commitments and contingencies (Note 5)
Stockholders’ equity (deficit)
Preferred stock, $0.001 par value; 5,000,000 shares authorized as of September 30, 2015 and none authorized as of December 31, 2014: no shares issued and outstanding as of September 30, 2015
Common stock, $0.001 par value; 100,000,000 shares authorized as of September 30, 2015 and 45,000,000 shares authorized as of December 31, 2014; 26,322,494 shares issued and outstanding as of September 30, 2015 and 691,312 shares issued and outstanding as of December 31, 2014	27	1
Additional paid-in capital	121,556	3,593
Accumulated deficit	(66,962)	(47,775)
Total stockholders’ equity (deficit)	54,621	(44,181)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 62,079	6,644
Convertible Preferred Stock [Member]
Current liabilities:
Convertible preferred stock, $0.001 par value; no shares authorized as of September 30, 2015 and 34,371,305 shares authorized as of December 31, 2014; no shares issued and outstanding as of September 30, 2015 and 8,268,531 shares issued and outstanding as of December 31, 2014		$ 39,556

Condensed Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Sep. 30, 2015	Dec. 31, 2014
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	0
Preferred stock, shares issued	0
Preferred stock, shares outstanding	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	45,000,000
Common stock, shares issued	26,322,494	691,312
Common stock, shares outstanding	26,322,494	691,312
Convertible Preferred Stock [Member]
Convertible preferred stock, par value	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0	34,371,305
Convertible preferred stock, shares issued	0	8,268,531
Convertible preferred stock, shares outstanding	0	8,268,531

Condensed Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
License Revenue	$ 7	$ 10	$ 21	$ 21
Operating Expenses:
Research and development	3,533	2,088	11,939	5,263
General and administrative	1,373	1,490	3,549	2,618
Total operating expenses	4,906	3,578	15,488	7,881
Loss from Operations	(4,899)	(3,568)	(15,467)	(7,860)
Other Income (expense):
Interest income	2	1	4	2
Interest expense	(95)	(357)	(1,100)	(520)
Loss on extinguishment of convertible promissory notes			(3,177)
Other income (expense), net	1	(71)	553	(267)
Net Loss and Comprehensive Loss	$ (4,991)	$ (3,995)	$ (19,187)	$ (8,645)
Net loss per share to common stockholders, basic and diluted	$ (0.19)	$ (5.89)	$ (1.12)	$ (14.75)
Weighted average common shares outstanding, basic and diluted	26,322,494	678,189	17,203,279	586,111

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash Flows from Operating Activities
Net loss	$ (19,187)	$ (8,645)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	98	37
Stock based compensation expense	444	208
Change in fair value of preferred stock warrant liability and derivative liability	(520)	267
Non-cash interest expense	192	(69)
Amortization of loan and convertible promissory notes discount	773
Loss on extinguishment of convertible promissory notes	3,177
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(881)	(34)
Other assets	(39)
Accounts payable	503	367
Accrued expenses	(335)	975
Deferred licensing revenue	(21)	(22)
Net cash used in operating activities	(15,796)	(6,916)
Cash Flows from Investing Activities
Purchase of property and equipment	(280)	(83)
Net cash used in investing activities	(280)	(83)
Cash Flows from Financing Activities
Proceeds from issuance of common stock upon exercise of options, net	149	228
Proceeds from issuance of common stock, net	67,908
Deferred public offering costs		(185)
Proceeds from loans payable		2,208
Repayment of loans payable	4,000	5,000
Proceeds from convertible promissory notes		(708)
Net cash provided by financing activities	72,057	6,543
Net increase/(decrease) in cash and cash equivalents	55,981	(456)
Cash and cash equivalents at beginning of period	3,897	9,781
Cash and cash equivalents at end of period	59,878	9,325
Supplemental Cash Flow Information
Cash paid for interest	45	595
Supplemental Disclosures of Non-cash Financing Activities
Issuance of preferred stock warrants		103
Conversion of preferred stock warrants to common stock warrants	347
Conversion of preferred stock to common stock	39,556
Increase accrual of deferred public offering costs		945
Increase of derivative related to convertible promissory notes at issuance	1,196	1,067
Increase of beneficial conversion feature for convertible promissory notes	$ 519	$ 2,276

Formation and Business of the Company

9 Months Ended

Sep. 30, 2015

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Formation and Business of the Company

1.	Formation and Business of the Company

Carbylan Therapeutics, Inc. (the “Company”) is a clinical-stage specialty pharmaceutical company focused on the development and commercialization of novel and proprietary combination therapies that address significant unmet medical needs. The Company’s initial focus is on the development of Hydros-TA, its proprietary, potentially best-in-class intra-articular injectable product candidate to treat pain associated with osteoarthritis of the knee. The Company was incorporated in the state of Delaware on March 26, 2004 as Sentrx Surgical, Inc. The name of the Company was changed to Carbylan Biosurgery, Inc. on December 14, 2005. The name of the Company was changed to Carbylan Therapeutics, Inc. on March 7, 2014.

Since commencing operations in 2004, the Company has devoted substantially all of its efforts to identifying and developing product candidates for therapeutic markets, recruiting personnel and raising capital. The Company has devoted predominantly all of its resources to the preclinical and clinical development of, and manufacturing capabilities for, Hydros-TA. The Company has never been profitable and has not yet commenced commercial operations.

At September 30, 2015, the Company had an accumulated deficit of approximately $67.0 million. The Company expects to incur increased research and development expenses during the current Phase 3 trial of Hydros-TA and when the Company initiates the second Phase 3 trial of Hydros-TA. Management’s plans with respect to these matters include utilizing a substantial portion of the Company’s capital resources and efforts in completing the development and obtaining regulatory approval for Hydros-TA and expanding the Company’s organization.

In March 2015, the Company’s board of directors and stockholders approved a 4-for-1 reverse stock split of the Company’s common and preferred stock. The Company filed an amendment to its certificate of incorporation effecting the reverse stock split on March 13, 2015. All issued and outstanding common stock, convertible preferred stock, warrants for preferred stock, options for common stock and per share amounts contained in the condensed financial statements have been retroactively adjusted to reflect this reverse stock split for all periods presented.

On April 8, 2015, the Company’s registration statement on Form S-1 (File No. 333-201278) relating to the Initial Public Offering (“IPO”) of its common stock was declared effective by the SEC. The IPO closed on April 14, 2015 at which time the Company sold 14,950,000 shares of common stock, which included 1,950,000 shares of common stock purchased by the underwriters upon the full exercise of their option to purchase additional shares of common stock. The Company received cash proceeds of approximately $66.3 million from the IPO, net of underwriting discounts and commissions and IPO expenses paid by the Company.

Prior to the closing of the IPO, all outstanding shares of convertible preferred stock converted into 8,268,531 shares of common stock with the related carrying value of $39.6 million reclassified to common stock and additional paid-in capital. In addition, all convertible preferred stock warrants were converted into warrants exercisable for common stock and the convertible promissory notes were converted in to 2,287,120 shares of common stock.

On April 14, 2015, the Company filed its Amended and Restated Certificate of Incorporation, authorizing 105,000,000 shares of capital stock, including 100,000,000 shares of authorized common stock and 5,000,000 shares of authorized undesignated preferred stock. Both the common stock and preferred stock have a par value of $0.001 per share. There are no shares of preferred stock outstanding at September 30, 2015.

Summary of Significant Accounting Policies and Basis of Presentation

9 Months Ended

Sep. 30, 2015

Accounting Policies [Abstract]

Summary of Significant Accounting Policies and Basis of Presentation

2.Summary of Significant Accounting Policies and Basis of Presentation

Basis of Presentation

The accompanying interim condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and on a basis consistent with the annual financial statements, and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the periods presented. These interim financial results are not necessarily indicative of the results to be expected for the year ending December 31, 2015, or for any other future annual or interim period. The accompanying unaudited condensed financial statements should be read in conjunction with the audited financial statements and the related notes thereto included in the Company’s Prospectus filed pursuant to Rule 424(b)(4) on April 8, 2015 with the SEC (the “Prospectus”).

Use of Estimates

The preparation of the interim condensed financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. On an ongoing basis, the Company evaluates its estimates, including those related to common stock, stock-based compensation expense, warrant liabilities, accruals, derivative liability, deferred tax valuation allowance and revenue recognition. Management bases its estimates on historical experience or on various other assumptions, including information received from its service providers, which it believes to be reasonable under the circumstances. Actual results could differ from those estimates.

Risks and Uncertainties

The product candidates developed by the Company require approvals from the U.S. Food and Drug Administration (“FDA”) or foreign regulatory agencies prior to commercial sales. There can be no assurance that the Company’s current and future product candidates will receive the necessary approvals. If the Company is denied approval or approval is delayed, it may have a material adverse impact on the Company’s business and its financial statements.

The Company is subject to risks common to companies in the pharmaceutical industry with no commercial operating history, including, but not limited to, dependency on the clinical and commercial success of its product candidates, ability to obtain regulatory approval of its product candidates, the need for substantial additional financing to achieve its goals, uncertainty of broad adoption of its approved products, if any, by physicians and consumers, significant competition and untested manufacturing capabilities.

The Company expects to incur substantial operating losses for the next several years and will need to obtain additional financing in order to launch and commercialize any products or product candidates for which it receives regulatory approval. There can be no assurance that such financing will be available or will be at terms acceptable by the Company.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents. The Company invests its excess cash in money market accounts. The Company’s cash and cash equivalents are held by a single financial institution and all cash is held in the United States. Such deposits may, at times, exceed federally insured limits. The Company has not recognized any losses during the periods presented and management does not believe that the Company is exposed to significant credit risk from its cash and cash equivalents.

Segment Reporting

The Company manages its operations as a single operating segment for the purposes of assessing performance and making operating decisions. The Company is a specialty pharmaceutical company focused on the development and commercialization of novel and proprietary combination therapies that address significant unmet medical needs. No product revenue has been generated since inception, and all assets are held in the United States.

Cash and Cash Equivalents

The Company considers all highly liquid investments purchased with an original maturity date of 90 days or less on the date of purchase to be cash equivalents. The Company invests its cash in bank deposits and money market funds.

Restricted Cash

The Company is required to guarantee the credit limit on its corporate credit card with a certificate of deposit of $50,000. The balance is included as restricted cash on the condensed balance sheets.

Beneficial Conversion Feature

From time to time, the Company may issue convertible promissory notes that have conversion prices that create an embedded beneficial conversion feature on the issuance date. A beneficial conversion feature exists on the date a convertible promissory note is issued when the fair value of the underlying common stock to which the note is convertible into is in excess of the remaining unallocated proceeds of the note after first considering the allocation of a portion of the note proceeds to the fair value of any attached equity instruments, if any related equity instruments were granted with the debt. The intrinsic value of the beneficial conversion feature is recorded as a debt discount with a corresponding amount to additional paid-in capital. The debt discount is amortized to interest expense over the term of the note using the effective interest method.

Embedded Derivatives Related to Convertible Promissory Notes

Embedded derivatives that are required to be bifurcated from the underlying debt instrument (i.e. host) are accounted for and valued as a separate financial instrument. The Company evaluated the terms and features of the convertible promissory notes issued in September 2014 and February 2015 and identified embedded derivatives requiring bifurcation and accounting at fair value because the economic and contractual characteristics of the embedded derivatives met the criteria for bifurcation and separate accounting due to the conversion features (see Note 7 for a description of the conversion features).

Fair Value of Financial Instruments

Fair value accounting is applied for all financial assets and liabilities, and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis (at least annually).

Property and Equipment, Net

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which are as follows:

Computer equipment		3 years
Lab equipment		3 years
Furniture and fixtures		5 years
Machinery and equipment		3 years
Manufacturing equipment		7 years

Leasehold improvements are amortized over the lesser of their useful lives or the term of the lease. Upon sale or retirement of the assets, the cost and related accumulated depreciation are removed from the balance sheet and the resulting gain or loss is recognized in the accompanying interim condensed statement of operations and comprehensive loss in other income (expense), net. Maintenance and repairs are charged to operations as incurred.

Pre-clinical and Clinical Trial Accruals

The Company’s clinical trial accruals are based on estimates of patient enrollment and related costs at clinical investigator sites as well as estimates for the services received and efforts expended pursuant to contracts with clinical research organizations that conduct and manage preclinical and clinical trials on the Company’s behalf. If contracts are modified based upon changes in the clinical trial protocol or scope of work to be performed, the Company modifies the estimates of accrued expenses accordingly. To date, there have been no material differences from its estimates to the amount actually incurred.

Preferred Stock Warrant Liability

The Company accounts for its warrants as either equity or liabilities based upon the characteristics and provisions of each instrument. Warrants classified as derivative liabilities are recorded on the Company’s accompanying balance sheets at their fair value on the date of issuance and are revalued at each subsequent balance sheet date, with fair value changes recognized as increases or reductions to other income (expense), net in the statements of operations and comprehensive loss.

Research and Development Expenditures

Costs incurred to further the Company’s research and development include salaries and related employee benefits, stock-based compensation expense, costs associated with clinical studies, nonclinical research and development activities, regulatory activities, research-related overhead expenses and fees paid to external service providers and contract research and manufacturing organizations that conduct certain research and development activities on behalf of the Company.

Stock-Based Compensation

The Company maintains performance incentive plans under which incentive stock options and non-qualified stock options may be granted to employees and non-employees. The Company accounts for stock-based compensation arrangements with employees in accordance with ASC 718, Compensation — Stock Compensation. ASC 718 requires the recognition of compensation expense, using a fair value-based method, for costs related to all share-based payments including stock options.

The Company’s determination of the fair value of stock options on the date of grant utilizes the Black-Scholes option-pricing model, and is impacted by its common stock price as well as changes in assumptions regarding a number of subjective variables. These variables include, but are not limited to, expected term that options will remain outstanding, expected common stock price volatility over the term of the option awards, risk-free interest rates and expected dividends.

The fair value is recognized over the period during which an optionee is required to provide services in exchange for the option award, known as the requisite service period (usually the vesting period), on a straight-line basis. Stock-based compensation expense recognized at fair value includes the impact of estimated forfeitures. The Company estimates future forfeitures at the date of grant and revises the estimates, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

Income Taxes

The Company accounts for income taxes under the asset and liability method. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized.

The Company accounts for uncertain tax positions in accordance with ASC 740-10, Accounting for Uncertainty in Income Taxes. The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.

Net Loss per Share to Common Stockholders

Basic earnings per share to common stockholders is computed by dividing net loss by the weighted average number of shares of common stock outstanding during the periods presented. The computation of diluted earnings per share is similar to the computation of basic earnings per share, except that the denominator is increased for the assumed exercise of dilutive options and other potentially dilutive securities using the treasury stock method unless the effect is antidilutive.

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards update (“ASU”) 2014-09, “Revenue from Contracts with Customers,” requiring an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The updated standard will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective and permits the use of either the retrospective or modified retrospective transition method. In July 2015, the FASB voted to defer the effective date for annual reporting periods beginning after December 15, 2017 (including interim reporting periods within those periods) and permitted early adoption of the standard, but not before the original effective date of December 15, 2016. The Company expects to adopt the updated standard in the first quarter of fiscal 2018. The Company has not yet selected a transition method and is currently evaluating the effect that the updated standard will have on the financial statements and related disclosures.

In August 2014, the FASB issued ASU NO. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern, or ASU 2014-15. ASU 2014-15 requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued and provides guidance on determining when and how to disclose going concern uncertainties in the financial statements. Certain disclosures will be required if conditions give rise to substantial doubt about an entity’s ability to continue as a going concern. ASU 2014-15 applies to all entities and is effective for annual and interim reporting periods ending after December 15, 2016, with early adoption permitted. The Company does not expect that the adoption of this guidance will have a material effect on its financial statements.

Fair Value Measurements

9 Months Ended

Sep. 30, 2015

Fair Value Disclosures [Abstract]

Fair Value Measurements

3.	Fair Value Measurements

The Company follows ASC 820-10, Fair Value Measurements and Disclosures, which among other things, defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, a three-tier fair value hierarchy has been established, which prioritizes the inputs used in measuring fair value as follows:

Level 1

Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.

Level 2

Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the asset or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life.

Level 3

Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model.

The Company’s investments in money market funds are measured at fair value on a recurring basis. These money market funds are actively traded and reported daily through a variety of sources. The fair value of the money market fund investments is classified as Level 1.

The fair value of the certificates of deposit is classified as Level 2 due to the nature of a contractual restriction with a financial institution that requires the certificate of deposit to remain in place as collateral for the credit card, and therefore the ability to liquidate the investment is limited.

As of September 30, 2015, based on borrowing rates that are available to the Company for loans of similar terms and consideration of the Company’s credit risk, the carrying value of the loan payable approximates the fair value using Level 2 inputs.

There were no transfers between Level 1 and Level 2 during the periods presented.

In certain cases where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3. During 2014 and through the date of the IPO in April 2015, the Company estimated the fair value of the warrant liability. The Company used the Black-Scholes option-pricing method to calculate the fair value of the warrant liability. Generally, increases or decreases in the fair value of the underlying convertible preferred stock resulted in a similar impact in the fair value measurement of the warrant liability.

The fair value of the derivative of the September 2014 and February 2015 convertible promissory notes (see Note 7) was recorded as a derivative liability instrument that is measured at fair value at each reporting period. In connection with the IPO, the convertible promissory notes were converted in to shares of common stock, and the derivative liability is therefore not present at September 30, 2015. At December 31, 2014, the Company remeasured the fair value of the derivative for the September 2014 convertible promissory notes by estimating the fair value of the convertible promissory notes with and without the conversion derivative. To calculate the fair value of the convertible promissory notes without the conversion derivative, the Company estimated the present value of the expected cash payments at an assumed discount rate. To calculate the fair value of the convertible promissory notes with the conversion feature, the Company calculated the present value of the convertible promissory notes upon conversion at an initial public offering, and the present value of the convertible promissory notes at an equity financing. The Company applied a probability of occurrence to all of the conversion scenarios and estimated a weighted value of the notes with the conversion feature. The difference between the fair value of the convertible promissory notes with and without the conversion features is the fair value of the derivative.

The following table presents the Company’s fair value hierarchy for assets and liabilities measured at fair value on a recurring basis:

	Fair Value Measurements as of September 30, 2015 (in thousands)
	Quoted Price in Active Markets for Identical Assets		Significant other Observable Inputs		Significant Unobservable Inputs
	Level 1		Level 2		Level 3		Total
Assets
Money market funds⁽¹⁾	$	59,803	$	—	$	—	$	59,803
Certificate of deposit		—		50		—		50
	$	59,803	$	50	$	—	$	59,853
Liabilities
Derivative liability	$	—	$	—	$	—	$	—
Preferred stock warrant liability		—		—		—		—
	$	—	$	—	$	—	$	—

	Fair Value Measurements as of December 31, 2014 (in thousands)
	Quoted Price in Active Markets for Identical Assets		Significant other Observable Inputs		Significant Unobservable Inputs
	Level 1		Level 2		Level 3		Total
Assets
Money market funds⁽¹⁾	$	3,825	$	—	$	—	$	3,825
Certificate of deposit		—		50		—		50
	$	3,825	$	50	$	—	$	3,875
Liabilities
Derivative liability	$	—	$	—	$	1,495	$	1,495
Preferred stock warrant liability		—		—		463		463
	$	—	$	—	$	1,958	$	1,958

(1)	Included in cash and cash equivalents in the Company’s condensed balance sheet.

The change in the fair value of the preferred stock warrant liability is summarized below:

Fair value as of December 31, 2014	$	463
Change in fair value recorded in other income (expense), net	$	(116	)
Conversion to common stock warrants at IPO date	$	(347	)
Fair value as of September 30, 2015	$	—

The following is a summary of the activity of the derivative liability for the nine months ended September 30, 2015:

Fair value as of December 31, 2014	$	1,495
Embedded derivative liability upon issuance of convertible promissory notes		1,196
Change in fair value recorded in other income (expense), net		(404	)
Automatic exercise of the derivative liability		(2,287	)
Fair value as of September 30, 2015	$	—

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Balance Sheet Components

9 Months Ended

Sep. 30, 2015

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Balance Sheet Components

4.	Balance Sheet Components

Property and Equipment, Net

The following table represents the components of property and equipment (in thousands):

	September 30,			December 31,
	2015			2014
Computer equipment	$	30		$	30
Lab equipment		676			543
Furniture and fixtures		21			21
Machinery and equipment		173			26
Leasehold improvement		55			55
		955			675
Less: Accumulated depreciation and amortization		(593	)		(495	)
Total property and equipment, net	$	362		$	180

Depreciation expense for the nine months ended September 30, 2015 and 2014, was $98,000, and $37,000, respectively.

Accrued Liabilities

(in thousands)

	September 30,		December 31,
	2015		2014
Accrued payroll and related expenses	$	706	$	723
Accrued legal expenses		48		159
Accrued research and clinical trial expenses		467		380
Accrued professional services		51		343
	$	1,272	$	1,605

Commitments and Contingencies

9 Months Ended

Sep. 30, 2015

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

5.	Commitments and Contingencies

Operating Lease

The Company leases its facilities under a noncancelable operating lease which expires on February 29, 2016. The terms of the lease agreement require the Company to provide a security deposit of $69,000. The security deposit is included in other assets on the accompanying condensed balance sheets. The Company has a sub-lease agreement with a tenant for approximately thirty-seven percent of the square footage of the corporate headquarters. Under this agreement, the Company receives $16,000 per month as rental income which is accounted for as a reduction of rent expense. The sub-lease agreement continues until February 29, 2016.

Gross rent expense for the three months ended September 30, 2015 and 2014 was $110,000 and $107,000, respectively, and for the nine months ended September 30, 2015 and 2014 was $328,000 and $324,000, respectively. The rental expense is reduced by the sublease rental income amounts of $50,000 and $48,000, respectively, for the three months ended September 30, 2015 and 2014 and $147,000 and $143,000, respectively, for the nine months ended September 30, 2015 and 2014.

On July 13, 2015, the Company entered into a lease for an 18,704 square foot facility located in Newark, California (the “Newark Lease”), which will serve as the Company’s future headquarters, with office, R&D and laboratory space. The Company is in the process of remodeling the facility to support future operations. Under the Newark Lease, the landlord is providing an allowance of up to $599,000 to fund appropriate improvements to the facility. The term of the Newark Lease commences when the landlord delivers possession of the facility to the Company, which is currently estimated to be February 2016.

Upon commencement of the Newark Lease, the initial term will be approximately six and a half years, with a monthly rental rate starting at $2.65 per square foot in the first year of the lease, escalating each year by 3.0%. The annual rent obligation is expected to be approximately $595,000 for the first year of the lease. The Company will also be responsible for certain other costs, such as insurance, taxes, utilities, maintenance and repairs, a property management fee, and reimbursement of certain expenses related to maintenance of common areas. The Company delivered a security deposit of approximately $149,000 in connection with the execution of the Newark Lease, and this amount is recorded in other assets on the condensed balance sheets.

The aggregate future minimum lease payments under the current and future operating lease are as follows:

Years ending December 31,	(in thousands)
2015	$	110
2016		618
2017		611
2018		629
2019		648
Remaining years		1,768
Total minimum lease payments	$	4,384

Indemnification

In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnification. The Company’s exposure under these agreements is unknown because it involves future claims that may be made against the Company but have not yet been made. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. However, the Company may record charges in the future as a result of these indemnification obligations. No amounts associated with such indemnifications have been recorded to date.

From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of business activities. The Company accrues a liability for such matters when it is probable that a liability has been incurred and that future expenditures can be reasonably estimated. There have been no contingent liabilities requiring accrual or disclosure at September 30, 2015.

Loan and Security Agreement

9 Months Ended

Sep. 30, 2015

Debt Disclosure [Abstract]

Loan and Security Agreement

6.	Loan and Security Agreement

In October 2011, the Company entered into a loan and security agreement (the “Loan and Security Agreement”) with a financial institution. In September 2014, the Loan and Security Agreement was amended. The interest rate is 3.95% per annum and the loan is repayable in thirty-six equal monthly installments, following an eighteen-month interest only period. The final balloon interest payment is approximately $0.6 million and is accreted over the life of the loan. The amendment was accounted for as a modification, and the unamortized debt discount as of the date of the modification is being amortized over the new loan period, using the effective interest rate method.

The Loan and Security Agreement contains customary representations and warranties, covenants, closing and advancing conditions, events of defaults and termination provisions. The Loan and Security Agreement provides that an event of default will occur if (1) the financial institution determines that it is the clear intention of the Company’s investors to not continue to fund the Company in the amounts and timeframe necessary to enable the Company to satisfy the Company’s financial obligations, (2) there is a material impairment in the financial institution’s security interest in the personal property that is the collateral, (3) the Company defaults in the payment of any amount payable under the agreement when due or (4) the Company breaches any negative covenant or certain affirmative covenants in the agreement (subject to a grace period in certain cases). The repayment of the loan is accelerated following the occurrence of an event of default or otherwise, which would require the Company to immediately pay an amount equal to: (i) all outstanding principal plus accrued but unpaid interest, (ii) the final payment, plus (iii) all other sums, that shall have become due and payable but have not been paid, including interest at the default rate with respect to any past due amounts. As of September 30, 2015, the Company was in compliance with all the covenants in the Loan and Security Agreement.

As discussed in Note 1, the Company has completed its IPO and believes it will be able to meet its payment obligations under the Loan and Security Agreement during the twelve months following the most recent balance sheet date. The Company has classified loan payments beyond twelve months to long term.

Aggregated annual payments due under the Loan and Security Agreement are as follows:

As of September 30, 2015 (in thousands)
2015	$	45
2016		1,775
2017		2,095
2018		1,391
Total payments		5,306
Less: Interest		(806	)
Present value of loans payable		4,500
Less: Debt discount		(91	)
Add: Final balloon payment		517
Less: Unamortized portion of final balloon payment		(360	)
Loans payable		4,566
Less: Current portion		(965	)
Loans payable, net of current portion	$	3,601

Convertible Promissory Notes

9 Months Ended

Sep. 30, 2015

Long Term Debt [Abstract]

Convertible Promissory Notes

7.	Convertible Promissory Notes

On September 29, 2014 and February 19, 2015, the Company entered into convertible note purchase agreements and issued convertible promissory notes (the “Notes”) in an aggregate principal amount of $5.0 million and $4.0 million, respectively, to several related parties that own more than 10% of the Company’s capital stock. All principal and accrued interest on the Notes was converted to the Company’s common stock upon the completion of the Company’s initial public offering in April 2015. Upon conversion, 2,287,120 shares of common stock were issued.

The Notes provided that upon completion of an initial public offering, the Notes would automatically convert into a number of shares of the Company’s common stock equal to the quotient obtained by dividing the entire principal amount and accrued interest on the Notes by 80% of the initial public offering price per share of the Company’s common stock. The Notes bore interest at a rate of 5% per annum, compounded annually.

Due to the automatic conversion features contained in the Notes, the actual number of shares of common stock or preferred stock that would be required if a conversion of the Notes was made through the issuance of the Company’s common or preferred stock could not be predicted prior to the conversion taking place. In addition, the conversion that would occur upon a change in control of the Company met the definition of a put option and was not closely related to the debt. As a result, the automatic conversion features and put option, exclusive of the Series B conversion feature, required derivative accounting treatment and were bifurcated from the Notes and marked to market each reporting period through the statement of operations and comprehensive loss. The fair value of the automatic conversion features and put option of the Notes, exclusive of the Series B conversion feature, were recorded as a derivative liability instrument and measured at fair value at each reporting period.

As of December 31, 2014, the Company estimated the fair value of the derivative by estimating the fair value of the Notes with and without the conversion derivative. To calculate the fair value of the Notes without the conversion derivative, the Company estimated the present value of the expected cash payments at an assumed discount rate of 8.25%. To calculate the fair value of the Notes with the conversion feature, the Company calculated the present value of the Notes upon conversion at an initial public offering, and the present value of the Notes at an equity financing. The risk-free rate for the assumed discount period is estimated at 0.05% and 0.15% in the respective conversion scenarios. The risk-free rate for the assumed discount period is estimated at 0.05% and 0.12% in the respective conversion scenarios at the valuation date of December 31, 2014. The Company applied a probability of occurrence to all of the conversion scenarios associated with the derivative and estimated a weighted value of the Notes with the conversion feature. The difference between the fair value of the Notes with and without the conversion features is the derivative. The fair value of the derivative was $1,495,000 as of December 31, 2014.

Upon issuance of the February 2015 Notes, the Company calculated the derivative liability using the same methodology and assumptions as those used as of December 31, 2014 because there were not significant changes in the Company or in the operations of the Company that had occurred in that intervening time period. The additional derivative liability recorded upon issuance of the February 2015 Notes was $1,196,000.

At April 8, 2015, the Company remeasured the fair value of the derivative liability for the Notes using a methodology similar to the methodology used at December 31, 2014, with a minimal discount period. The fair value of the derivative was $2,287,000.

The Company determined that the Notes contain a beneficial conversion feature related to the conversion feature of the Notes into Series B convertible preferred stock. The beneficial conversion feature results from the difference between the fair value of the Company’s common stock at the date of issuance and the Series B Preferred Stock Conversion price of $4.8104 at the date of issuance. The beneficial conversion feature amounted to $2,275,000 for the September 2014 Notes and $158,000 for the February 2015 Notes as of the date of issuance of the respective Notes, and was recorded as a debt discount that would be amortized through the maturity date of the Notes.

At April 8, 2015, the beneficial conversion feature amounted to $202,000 for the September 2014 Notes and $158,000 for the February 2015 Notes. The fair value of the shares issued upon conversion of the convertible promissory notes was first allocated to the beneficial conversion feature of $360,000.

At April 8, 2015, the loss on extinguishment of the convertible promissory notes was calculated as follows:


Fair value of common stock issued upon conversion of convertible promissory notes and accrued interest	$	11,435
Less:
Fair value of beneficial conversion feature on conversion date		(360	)
Net book value of convertible promissory notes		(5,611	)
Fair Value of derivative liability at conversion date		(2,287	)
Loss on extinguishment of convertible promissory notes	$	3,177

Convertible Preferred Stock Warrants

9 Months Ended

Sep. 30, 2015

Equity [Abstract]

Convertible Preferred Stock Warrants

8.	Convertible Preferred Stock Warrants

The Company issued warrants to purchase shares of the Company’s convertible preferred stock at various times in connection with loans payable. Immediately prior to the closing of the IPO, all convertible preferred stock warrants were converted in to warrants exercisable for common stock. The convertible preferred stock warrants outstanding as of December 31, 2014 were as follows (in thousands, except share and per share amounts):

	Number of Shares Underlying Warrants		Exercise Price per Share		Fair Value, as of December 31, 2014
Series A preferred stock		20,788	$	4.81	$	46
Series B preferred stock		103,941	$	4.81	$	417
		124,729			$	463

The fair value of the convertible preferred stock warrant liability was remeasured as of each period end. As of December 31, 2014, the Company remeasured the fair value using a Black-Scholes option-pricing method with the following assumptions: a weighted average remaining life of 6.7 years, an expected volatility of 58.9%, a weighted average risk-free interest rate of 1.80% and no expected dividend. As of April 14, 2015, the Company remeasured the fair value of the convertible preferred stock warrant liability using a Black-Scholes option-pricing method with the following assumptions: the Company’s IPO price of $5.00 per share, a weighted average remaining life of 6.4 years, an expected volatility of 58.3%, a weighted average risk-free interest rate of 1.51% and no expected dividend. The Company evaluated the down-round protection provisions of the warrant agreements by using a Monte Carlo simulation model and determined that the impact of such provisions was immaterial to the fair value of the warrants at the reporting dates. The assumptions are further described as follows:

Expected Time to liquidity event — The Company estimated the time to liquidity event based on management’s analysis of the business, market conditions and clinical development.

Expected Volatility — The Company estimates the expected volatility based on the average volatility for comparable publicly traded biopharmaceutical companies over a period equal to the expected time to liquidity event. When selecting the publicly traded biopharmaceutical companies, the Company selected companies with comparable characteristics to it, including enterprise value and risk profiles, and with historical share price information sufficient to meet the time to liquidity event. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available.

Risk-Free Interest Rate — The risk-free interest rate is based on U.S. Treasury zero-coupon issues with remaining terms similar to the expected time to the liquidity event.

Expected Dividend Rate — The Company has never paid any dividends and does not plan to pay dividends in the foreseeable future, and, therefore, used an expected dividend rate of zero in the valuation model.

On April 8, 2015, the convertible preferred stock warrants automatically converted to common stock warrants. The convertible preferred stock warrant liability was reclassified to additional paid-in capital. During June 2015, the holder of the common stock warrants exercised those warrants for 56,545 shares of common stock in a cashless exercise.

Common Stock

9 Months Ended

Sep. 30, 2015

Federal Home Loan Banks [Abstract]

Common Stock

9.	Common Stock

As of September 30, 2015 the Company’s Amended and Restated Certificate of Incorporation, as amended, has authorized 100,000,000 shares of common stock at $0.001 par value.

Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends, as may be declared by the board of directors. As of September 30, 2015, no dividends have been declared.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29-31)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB TOPIC 4.C)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6405834&loc=d3e23285-112656

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

+ Details

Stock Option Plan

9 Months Ended

Sep. 30, 2015

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Option Plan

10.	Stock Option Plan

Incentive stock options are granted with exercise prices not less than the estimated fair value of common stock, and non-statutory stock options may be granted with an exercise price of not less than 100% of the estimated fair value of the common stock on the date of grant. Options granted under the Plan expire no later than 10 years from the date of grant. Incentive stock options granted under the Plan vest over periods determined by the Board of Directors, generally over four years. Non-statutory stock options vest based on the terms of the individual agreement, generally from nine months to four years.

In April 2014, the Company terminated the 2004 Plan and the board of directors approved the 2014 Stock Option Plan (the 2014 Plan), authorizing 250,000 shares for issuance under the 2014 Plan. Shares underlying any outstanding stock awards or stock option grants previously awarded remain subject to the terms of the 2004 Plan. Any shares available for grant or any shares canceled or forfeited prior to vesting or exercise subsequent to the termination of the 2004 Plan became available for use under the 2014 Plan. Upon the effectiveness of the 2014 Plan, the Company ceased granting any equity awards under the 2004 Plan.

In January and February 2015, the board of directors and stockholders, respectively, approved the 2015 Equity Plan (the “2015 Equity Plan”). All future awards will be granted under the 2015 Plan. In connection with the IPO, the Company terminated the 2014 Plan. Shares underlying any outstanding stock option grants previously awarded under the 2014 Plan remain subject to the terms of such plan. Any shares available for grant or any shares canceled or forfeited prior to vesting or exercise subsequent to the termination of the 2014 Plan became available for use under the 2015 Plan.

As of September 30, 2015, options for 610,891 shares have been issued under the 2015 Equity Plan. The maximum number of shares of the Company’s common stock that may be delivered in satisfaction of awards under the 2015 Equity Plan is 1,532,534 shares, inclusive of 750,000 shares authorized upon creation of the 2015 Plan. The number of shares available for issuance under the Company’s 2015 Equity Plan will be increased on the first day of each fiscal year beginning in 2016, by an amount equal to the lessor of (1) 1,200,000 shares of stock and (2) four percent (4%) of the outstanding shares of stock on the last day of the immediately preceding year.

As of September 30, 2015, the Company had 1,722,262 shares issuable upon exercise of outstanding option awards.

In July 2015, the board of directors approved a non-qualified stock option grant of 165,903 shares of the Company’s common stock for an employee as an inducement grant in connection with his commencement of employment. The grant was issued outside of the 2015 Equity Plan. Stockholder approval was not required for this grant in reliance upon the employment inducement award exemption provided by NASDAQ Rule 5635(c)(4).

Total stock-based compensation expense related to options and awards granted was allocated as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Research and Development	$	86	$	60	$	96	$	78
General and administrative		203		40		348		130
Total	$	289	$	100	$	444	$	208

Related Party Transactions

9 Months Ended

Sep. 30, 2015

Related Party Transactions

11.	Related Party Transactions

In September 2014 and February 2015, the Company issued the Notes to several related parties that own more than 10% of the Company’s capital stock (see Note 7). Upon completion of the IPO, those Notes were converted in to shares of the Company’s common stock.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References + Details

Income Taxes

9 Months Ended

Sep. 30, 2015

Income Tax Disclosure [Abstract]

Income Taxes

12.	Income Taxes

The Company’s effective tax rate is 0% for income tax for the three and nine months ended September 30, 2015 and the Company expects that its effective tax rate for the full year 2015 will be 0%. Based on the weight of available evidence, including cumulative losses since inception and expected future losses, the Company has determined that it is more likely than not that the deferred tax asset amount will not be realized and therefore a valuation allowance has been provided on net deferred tax assets.

The Company has substantial net operating loss carry forwards available to offset future taxable income for federal and state income tax purposes. The ability to utilize the net operating losses may be limited due to changes in our ownership as defined by Section 382 of the Internal Revenue Code (the “Code”). Under the provisions of Sections 382 and 383 of the Code, a change of control, as defined in the Code, may impose an annual limitation on the amount of the Company’s net operating loss and tax credit carryforwards, and other tax attributes that can be used to reduce future tax liabilities.

The Company files tax returns for U.S. Federal and State of California. The Company is not currently subject to any income tax examinations. Since the Company’s inception, the Company had incurred losses from operations, which generally allows all tax years to remain open.

The gross amount of unrecognized tax benefits as of September 30, 2015 is approximately $0.6 million related to the reserve on R&D credits, none of which will affect the effective tax rate if recognized due to the valuation allowance. The Company does not expect any material changes in the next 12 months in unrecognized tax benefits.

The Company recognizes interest and/or penalties related to uncertain tax positions. To the extent accrued interest and penalties do not ultimately become payable, amounts accrued will be reduced and reflected in the period that such determination is made. Any interest and penalties are recognized in income tax expense. The Company currently has no interest and penalties related to uncertain tax positions.

Subsequent Events

9 Months Ended

Sep. 30, 2015

Subsequent Events [Abstract]

Subsequent Events

13.	Subsequent Events

In October 2015, the Company paid approximately $980,000 to the landlord of the Newark Lease for tenant improvement work to be performed. The Company will account for this payment as an addition to leasehold improvements.

Summary of Significant Accounting Policies and Basis of Presentation (Policies)

9 Months Ended

Sep. 30, 2015

Accounting Policies [Abstract]

Basis of Presentation

Use of Estimates

Risks and Uncertainties

Concentration of Credit Risk

Segment Reporting

Cash and Cash Equivalents

Restricted Cash

Beneficial Conversion Feature

Embedded Derivatives Related to Convertible Promissory Notes

Fair Value of Financial Instruments

Property and Equipment, Net

Computer equipment		3 years
Lab equipment		3 years
Furniture and fixtures		5 years
Machinery and equipment		3 years
Manufacturing equipment		7 years

Pre-clinical and Clinical Trial Accruals

Preferred Stock Warrant Liability

Research and Development Expenditures

Stock-Based Compensation

Income Taxes

Net Loss per Share to Common Stockholders

Recent Accounting Pronouncements

Summary of Significant Accounting Policies and Basis of Presentation (Tables)

9 Months Ended

Sep. 30, 2015

Accounting Policies [Abstract]

Estimated Useful Life of Property and Equipment

Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which are as follows:

Computer equipment		3 years
Lab equipment		3 years
Furniture and fixtures		5 years
Machinery and equipment		3 years
Manufacturing equipment		7 years

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2015

Summary of Fair Value Hierarchy for Assets and Liabilities Measured on a Recurring Basis

The following table presents the Company’s fair value hierarchy for assets and liabilities measured at fair value on a recurring basis:

	Fair Value Measurements as of September 30, 2015 (in thousands)
	Quoted Price in Active Markets for Identical Assets		Significant other Observable Inputs		Significant Unobservable Inputs
	Level 1		Level 2		Level 3		Total
Assets
Money market funds⁽¹⁾	$	59,803	$	—	$	—	$	59,803
Certificate of deposit		—		50		—		50
	$	59,803	$	50	$	—	$	59,853
Liabilities
Derivative liability	$	—	$	—	$	—	$	—
Preferred stock warrant liability		—		—		—		—
	$	—	$	—	$	—	$	—

	Fair Value Measurements as of December 31, 2014 (in thousands)
	Quoted Price in Active Markets for Identical Assets		Significant other Observable Inputs		Significant Unobservable Inputs
	Level 1		Level 2		Level 3		Total
Assets
Money market funds⁽¹⁾	$	3,825	$	—	$	—	$	3,825
Certificate of deposit		—		50		—		50
	$	3,825	$	50	$	—	$	3,875
Liabilities
Derivative liability	$	—	$	—	$	1,495	$	1,495
Preferred stock warrant liability		—		—		463		463
	$	—	$	—	$	1,958	$	1,958

(1)	Included in cash and cash equivalents in the Company’s condensed balance sheet.

Preferred Stock Warrant Liability [Member]

Summary of Change in Fair Value of Preferred Stock Warrant Liability

The change in the fair value of the preferred stock warrant liability is summarized below:

Fair value as of December 31, 2014	$	463
Change in fair value recorded in other income (expense), net	$	(116	)
Conversion to common stock warrants at IPO date	$	(347	)
Fair value as of September 30, 2015	$	—

Derivative Liability [Member]

Summary of Activity of Derivative Liability

The following is a summary of the activity of the derivative liability for the nine months ended September 30, 2015:

Fair value as of December 31, 2014	$	1,495
Embedded derivative liability upon issuance of convertible promissory notes		1,196
Change in fair value recorded in other income (expense), net		(404	)
Automatic exercise of the derivative liability		(2,287	)
Fair value as of September 30, 2015	$	—

Balance Sheet Components (Tables)

9 Months Ended

Sep. 30, 2015

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Components of Property and Equipment

The following table represents the components of property and equipment (in thousands):

	September 30,			December 31,
	2015			2014
Computer equipment	$	30		$	30
Lab equipment		676			543
Furniture and fixtures		21			21
Machinery and equipment		173			26
Leasehold improvement		55			55
		955			675
Less: Accumulated depreciation and amortization		(593	)		(495	)
Total property and equipment, net	$	362		$	180

Schedule of Accrued Liabilities

Accrued Liabilities

(in thousands)

	September 30,		December 31,
	2015		2014
Accrued payroll and related expenses	$	706	$	723
Accrued legal expenses		48		159
Accrued research and clinical trial expenses		467		380
Accrued professional services		51		343
	$	1,272	$	1,605

Commitments and Contingencies (Tables)

9 Months Ended

Sep. 30, 2015

Commitments And Contingencies Disclosure [Abstract]

Schedule of Future Minimum Lease Payments Under Current and Future Operating Lease

The aggregate future minimum lease payments under the current and future operating lease are as follows:

Years ending December 31,	(in thousands)
2015	$	110
2016		618
2017		611
2018		629
2019		648
Remaining years		1,768
Total minimum lease payments	$	4,384

Loan and Security Agreement (Tables)

9 Months Ended

Sep. 30, 2015

Debt Disclosure [Abstract]

Schedule of Annual Payments Due Under Loan and Security Agreement

Aggregated annual payments due under the Loan and Security Agreement are as follows:

As of September 30, 2015 (in thousands)
2015	$	45
2016		1,775
2017		2,095
2018		1,391
Total payments		5,306
Less: Interest		(806	)
Present value of loans payable		4,500
Less: Debt discount		(91	)
Add: Final balloon payment		517
Less: Unamortized portion of final balloon payment		(360	)
Loans payable		4,566
Less: Current portion		(965	)
Loans payable, net of current portion	$	3,601

Convertible Promissory Notes (Tables)

9 Months Ended

Sep. 30, 2015

Long Term Debt [Abstract]

Schedule of Loss on Extinguishment of Convertible Promissory Notes

At April 8, 2015, the loss on extinguishment of the convertible promissory notes was calculated as follows:


Fair value of common stock issued upon conversion of convertible promissory notes and accrued interest	$	11,435
Less:
Fair value of beneficial conversion feature on conversion date		(360	)
Net book value of convertible promissory notes		(5,611	)
Fair Value of derivative liability at conversion date		(2,287	)
Loss on extinguishment of convertible promissory notes	$	3,177

Convertible Preferred Stock Warrants (Tables)

9 Months Ended

Sep. 30, 2015

Equity [Abstract]

Schedule of Convertible Preferred Stock Warrants

Immediately prior to the closing of the IPO, all convertible preferred stock warrants were converted in to warrants exercisable for common stock. The convertible preferred stock warrants outstanding as of December 31, 2014 were as follows (in thousands, except share and per share amounts):

	Number of Shares Underlying Warrants		Exercise Price per Share		Fair Value, as of December 31, 2014
Series A preferred stock		20,788	$	4.81	$	46
Series B preferred stock		103,941	$	4.81	$	417
		124,729			$	463

- Definition

Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.

+ References + Details

Stock Option Plan (Tables)

9 Months Ended

Sep. 30, 2015

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Stock-Based Compensation Expense

Total stock-based compensation expense related to options and awards granted was allocated as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Research and Development	$	86	$	60	$	96	$	78
General and administrative		203		40		348		130
Total	$	289	$	100	$	444	$	208

Formation and Business of the Company - Additional Information (Detail) $ / shares in Units, $ in Thousands		9 Months Ended
	Apr. 14, 2015 USD ($) $ / shares shares	Sep. 30, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares
Organization And Basis Of Presentation [Line Items]
Entity Incorporation, State Name		Delaware
Date of incorporation		Mar. 26, 2004
Accumulated deficit \| $		$ 66,962	$ 47,775
Reverse stock split, description		In March 2015, the Company’s board of directors and stockholders approved a 4-for-1 reverse stock split of the Company’s common and preferred stock. The Company filed an amendment to its certificate of incorporation effecting the reverse stock split on March 13, 2015. All issued and outstanding common stock, convertible preferred stock, warrants for preferred stock, options for common stock and per share amounts contained in the condensed financial statements have been retroactively adjusted to reflect this reverse stock split for all periods presented
Reverse Stock Split, Conversion Ratio		0.25
Proceeds from issuance of common stock, net \| $		$ 67,908
Carrying value of convertible preferred stock into common stock \| $		$ 39,556
Capital stock, shares authorized	105,000,000
Common stock, shares authorized	100,000,000	100,000,000	45,000,000
Preferred stock, shares authorized	5,000,000	5,000,000	0
Preferred stock, par value \| $ / shares	$ 0.001	$ 0.001	$ 0.001
Common stock, par value \| $ / shares	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares outstanding		0
Convertible Promissory Notes [Member]
Organization And Basis Of Presentation [Line Items]
Conversion of notes into common stock, shares	2,287,120
Convertible Preferred Stock [Member]
Organization And Basis Of Presentation [Line Items]
Convertible preferred stock converted into common stock	8,268,531
Carrying value of convertible preferred stock into common stock \| $	$ 39,600
IPO [Member]
Organization And Basis Of Presentation [Line Items]
Proceeds from issuance of common stock, net \| $	$ 66,300
IPO [Member] \| Common Stock [Member]
Organization And Basis Of Presentation [Line Items]
Shares of common stock sold	14,950,000
Over-Allotment Option [Member]
Organization And Basis Of Presentation [Line Items]
Shares of common stock sold	1,950,000

Summary of Significant Accounting Policies Basis of Presentation - Additional Information (Detail) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Restricted Cash And Cash Equivalents Items [Line Items]
Certificates of Deposit Included as Restricted Cash	$ 50,000	$ 50,000
Certificate of Deposit [Member]
Restricted Cash And Cash Equivalents Items [Line Items]
Certificates of Deposit Included as Restricted Cash	$ 50,000

Summary of Significant Accounting Policies Basis of Presentation - Estimated Useful Life of Property and Equipment (Detail)	9 Months Ended
	Sep. 30, 2015
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property and equipment	3 years
Lab Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property and equipment	3 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property and equipment	5 years
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property and equipment	3 years
Manufacturing Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property and equipment	7 years

Fair Value Measurements - Additional Information (Detail)	Sep. 30, 2015 USD ($)
Fair Value Disclosures [Abstract]
Transfers between Level 1 and Level 2, Assets	$ 0
Transfers between Level 2 and Level 1, Assets	0
Transfers between Level 1 and Level 2, Liabilities	0
Transfers between Level 2 and Level 1, Liabilities	$ 0

Fair Value Measurements - Schedule of Fair Value Hierarchy for Assets and Liabilities Measured on a Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	$ 59,853	$ 3,875
Liabilities, Fair value		1,958
Derivative Liability [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair value		1,495
Preferred Stock Warrant Liability [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair value		463
Quoted Price in Active Markets for Identical Assets Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	59,803	3,825
Significant other Observable Inputs Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	50	50
Significant Unobservable Inputs Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair value		1,958
Significant Unobservable Inputs Level 3 [Member] \| Derivative Liability [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair value		1,495
Significant Unobservable Inputs Level 3 [Member] \| Preferred Stock Warrant Liability [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair value		463
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	59,803	3,825
Money Market Funds [Member] \| Quoted Price in Active Markets for Identical Assets Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	59,803	3,825
Certificate of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	50	50
Certificate of Deposit [Member] \| Significant other Observable Inputs Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	$ 50	$ 50

Fair Value Measurements - Summary of Change in Fair Value of Preferred Stock Warrant Liability (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Conversion to common stock warrants at IPO date	$ (347)
Preferred Stock Warrant Liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value as of December 31, 2014	463
Change in fair value recorded in other income (expense), net	(116)
Conversion to common stock warrants at IPO date	$ (347)

Fair Value Measurements - Summary of Activity of Derivative Liability (Detail) - Derivative Liability [Member] $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value as of December 31, 2014	$ 1,495
Embedded derivative liability upon issuance of convertible promissory notes	1,196
Change in fair value recorded in other income (expense), net	(404)
Automatic exercise of the derivative liability	$ (2,287)

Balance Sheet Components - Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 955	$ 675
Less: Accumulated depreciation and amortization	(593)	(495)
Total property and equipment, net	362	180
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	30	30
Lab Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	676	543
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	21	21
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	173	26
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 55	$ 55

Balance Sheet Components - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Property Plant And Equipment [Abstract]
Depreciation and amortization	$ 98	$ 37

Balance Sheet Components - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Payables And Accruals [Abstract]
Accrued payroll and related expenses	$ 706	$ 723
Accrued legal expenses	48	159
Accrued research and clinical trial expenses	467	380
Accrued professional services	51	343
Total accrued liabilities	$ 1,272	$ 1,605

Commitments and Contingencies - Additional Information (Detail)		3 Months Ended		9 Months Ended
	Jul. 13, 2015 USD ($) ft² $ / ft²	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)
Other Commitments [Line Items]
Rental income per month, sub-lease agreement				$ 16,000
Gross rent expense		$ 110,000	$ 107,000	328,000	$ 324,000
Sublease rental income		50,000	$ 48,000	147,000	$ 143,000
Indemnification Guarantee
Other Commitments [Line Items]
Contingent liabilities		0		$ 0
Facility located in Newark, California
Other Commitments [Line Items]
Security deposit	$ 149,000
Gross rent expense	$ 595,000
Area of square foot lease premises \| ft²	18,704
Estimated lease commencement date				Feb. 01, 2016
Operating leases, initial term of contract	6 years 6 months
Monthly rental rate per square foot \| $ / ft²	2.65
Annual base rent percentage	3.00%
Facility located in Newark, California \| Maximum [Member]
Other Commitments [Line Items]
Operating leases allowance for improvements	$ 599,000
Non Cancellable Operating Lease [Member]
Other Commitments [Line Items]
Lease expiration date				Feb. 29, 2016
Non Cancellable Operating Lease [Member] \| Other Noncurrent Assets [Member]
Other Commitments [Line Items]
Security deposit		$ 69,000		$ 69,000
Sublease Agreement [Member]
Other Commitments [Line Items]
Lease expiration date				Feb. 29, 2016
Percentage of square footage leased				37.00%

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Under Current and Future Operating Lease (Detail) $ in Thousands	Sep. 30, 2015 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2015	$ 110
2016	618
2017	611
2018	629
2019	648
Remaining years	1,768
Total minimum lease payments	$ 4,384

Loan and Security Agreement - Additional Information (Detail) - Loan and Security Agreement [Member] $ in Thousands	1 Months Ended	9 Months Ended
	Sep. 30, 2014 USD ($) Installment	Sep. 30, 2015 USD ($)
Debt Instrument [Line Items]
Debt instrument interest rate	3.95%
Loan repayment description		The loan is repayable in thirty-six equal monthly installments, following an eighteen-month interest only period. The final balloon interest payment is approximately $0.6 million and is accreted over the life of the loan.
Number of equal monthly installments \| Installment	36
Interest repayment period	18 months
Frequency of payments		Equal monthly installments
Final balloon interest payment \| $	$ 600	$ 517
Event of default description		The Loan and Security Agreement provides that an event of default will occur if (1) the financial institution determines that it is the clear intention of the Company’s investors to not continue to fund the Company in the amounts and timeframe necessary to enable the Company to satisfy the Company’s financial obligations, (2) there is a material impairment in the financial institution’s security interest in the personal property that is the collateral, (3) the Company defaults in the payment of any amount payable under the agreement when due or (4) the Company breaches any negative covenant or certain affirmative covenants in the agreement (subject to a grace period in certain cases). The repayment of the loan is accelerated following the occurrence of an event of default or otherwise, which would require the Company to immediately pay an amount equal to: (i) all outstanding principal plus accrued but unpaid interest, (ii) the final payment, plus (iii) all other sums, that shall have become due and payable but have not been paid, including interest at the default rate with respect to any past due amounts.

Loan and Security Agreement - Annual Payments Due Under Loan and Security Agreement (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Debt Instrument [Line Items]
Less: Current portion	$ (965)	$ (4,435)
Loans payable, net of current portion	3,601
Loan and Security Agreement [Member]
Debt Instrument [Line Items]
2015	45
2016	1,775
2017	2,095
2018	1,391
Total payments	5,306
Less: Interest	(806)
Present value of loans payable	4,500
Less: Debt discount	(91)
Final balloon interest payment	517		$ 600
Less: Unamortized portion of final balloon payment	(360)
Loans payable	4,566
Less: Current portion	(965)
Loans payable, net of current portion	$ 3,601

Convertible Promissory Notes - Additional Information (Detail) - USD ($)		9 Months Ended	12 Months Ended
	Apr. 08, 2015	Sep. 30, 2015	Dec. 31, 2014	Feb. 19, 2015	Sep. 29, 2014
Debt Instrument [Line Items]
Derivative liability			$ 1,495,000
Convertible Promissory Notes [Member]
Debt Instrument [Line Items]
Initial public offering period		April 2015
Debt instrument interest rate		5.00%
Debt instrument payment terms		Annually
Present value of the notes assumed discount rate		8.25%
Derivative liability	$ 2,287,000		$ 1,495,000
Debt instrument conversion price		$ 4.8104
Debt instrument, convertible, beneficial conversion feature	360,000
Convertible Promissory Notes [Member] \| Fair Value of Notes With Conversion Derivative [Member]
Debt Instrument [Line Items]
Risk-free interest rate		0.05%	0.05%
Convertible Promissory Notes [Member] \| Fair Value of Notes without Conversion Derivative [Member]
Debt Instrument [Line Items]
Risk-free interest rate		0.15%	0.12%
Convertible Promissory Notes [Member] \| Related Parties that own more than ten percent of the company capital [Member]
Debt Instrument [Line Items]
Convertible debt, aggregate principal amount				$ 4,000,000	$ 5,000,000
Debt instrument conversion rate		80.00%
Convertible Promissory Notes [Member] \| Related Parties that own more than ten percent of the company capital [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Ownership held by related parties		10.00%
February 2015 Notes [Member]
Debt Instrument [Line Items]
Fair value of derivative liability at issuance		$ 1,196,000
Debt instrument, convertible, beneficial conversion feature	158,000	158,000
September 2014 Notes [Member]
Debt Instrument [Line Items]
Debt instrument, convertible, beneficial conversion feature	$ 202,000	$ 2,275,000

Convertible Promissory Notes - Schedule of Loss on Extinguishment of Convertible Promissory Notes (Detail) - USD ($)		9 Months Ended
	Apr. 08, 2015	Sep. 30, 2015	Dec. 31, 2014
Extinguishment Of Debt [Line Items]
Fair Value of derivative liability at conversion date			$ (1,495,000)
Loss on extinguishment of convertible promissory notes		$ 3,177,000
Convertible Promissory Notes [Member]
Extinguishment Of Debt [Line Items]
Fair value of beneficial conversion feature on conversion date	$ (360,000)
Net book value of convertible promissory notes	(5,611,000)
Fair Value of derivative liability at conversion date	(2,287,000)		$ (1,495,000)
Loss on extinguishment of convertible promissory notes	3,177,000
Convertible Promissory Notes [Member] \| Common Stock [Member]
Extinguishment Of Debt [Line Items]
Fair value of common stock issued upon conversion of convertible promissory notes and accrued interest	$ 11,435,000

Convertible Preferred Stock Warrants - Schedule of Convertible Preferred Stock Warrants (Detail) $ / shares in Units, $ in Thousands	Dec. 31, 2014 USD ($) $ / shares shares
Class of Warrant or Right [Line Items]
Number of Shares Underlying Warrants \| shares	124,729
Fair Value \| $	$ 463
Series A Convertible Preferred Stock [Member]
Class of Warrant or Right [Line Items]
Number of Shares Underlying Warrants \| shares	20,788
Warrant Exercise price,per share \| $ / shares	$ 4.81
Fair Value \| $	$ 46
Series B Convertible Preferred Stock [Member]
Class of Warrant or Right [Line Items]
Number of Shares Underlying Warrants \| shares	103,941
Warrant Exercise price,per share \| $ / shares	$ 4.81
Fair Value \| $	$ 417

Convertible Preferred Stock Warrants - Additional Information (Detail) - Series B Warrants [Member] - $ / shares		12 Months Ended
	Apr. 14, 2015	Dec. 31, 2014	Jun. 30, 2015
Class of Warrant or Right [Line Items]
Weighted average remaining life	6 years 4 months 24 days	6 years 8 months 12 days
Expected volatility rate	58.30%	58.90%
Weighted average risk-free interest rate	1.51%	1.80%
Expected dividend rate	0.00%	0.00%
Common stock warrants cashless exercise			56,545
IPO [Member]
Class of Warrant or Right [Line Items]
Offering price per share	$ 5.00

Common Stock - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2015	Apr. 14, 2015	Dec. 31, 2014
Equity [Abstract]
Common stock, par value	$ 0.001	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000	45,000,000
Description of voting rights to shareholders	Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders.
Common stock dividends declared	$ 0

Stock Option Plan - Additional Information (Detail) - shares		1 Months Ended	9 Months Ended
	Sep. 30, 2015	Jul. 31, 2015	Sep. 30, 2015	Apr. 30, 2014
2004 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted, vesting period			4 years
Stock incentive plan, termination period			2014-04
2004 Stock Incentive Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted, expiration period			10 years
2004 Stock Incentive Plan [Member] \| Non-Statutory Stock Options [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted exercise price, based on percentage of estimated fair value			100.00%
Stock options granted, vesting period			9 months
2004 Stock Incentive Plan [Member] \| Non-Statutory Stock Options [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted, vesting period			4 years
2014 Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized				250,000
2015 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	750,000		750,000
Stock option, shares issued	610,891
Shares available for future awards	1,532,534		1,532,534
Number of shares available for issuance	1,200,000		1,200,000
Percentage of maximum outstanding shares of stock	4.00%
Shares issuable upon exercise of outstanding option awards	1,722,262		1,722,262
Share-based compensation arrangement by share-based payment award, description			The number of shares available for issuance under the Company’s 2015 Equity Plan will be increased on the first day of each fiscal year beginning in 2016, by an amount equal to the lessor of (1) 1,200,000 shares of stock and (2) four percent (4%) of the outstanding shares of stock on the last day of the immediately preceding year.
Non-Qualified Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, shares issued		165,903

Stock Option Plan - Schedule of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock based compensation expense	$ 289	$ 100	$ 444	$ 208
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock based compensation expense	86	60	96	78
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock based compensation expense	$ 203	$ 40	$ 348	$ 130

Related Party Transactions - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2015
Minimum [Member] \| Convertible Promissory Notes [Member] \| Related Parties that own more than ten percent of the company capital [Member]
Related Party Transaction [Line Items]
Ownership held by related parties	10.00%

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Effective income tax rate	0.00%	0.00%
Gross unrecognized tax benefits related to reserve on R&D credits	$ 600,000	$ 600,000
Material changes in the next 12 months in unrecognized tax benefits	$ 0	0
Interest and penalties related to uncertain tax positions		$ 0
Forecast [Member]
Operating Loss Carryforwards [Line Items]
Effective income tax rate			0.00%

Subsequent Events - Additional Information (Detail)	1 Months Ended
Subsequent Events - Additional Information (Detail)	Oct. 31, 2015 USD ($)
Facility located in Newark, California \| Subsequent Event [Member]
Operating Leased Assets [Line Items]
Payment to landlord for tenant improvements	$ 980,000