Invuity (IVTY) 10-K 25 Mar 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Mar. 22, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Trading Symbol	IVTY
Entity Registrant Name	Invuity, Inc.
Entity Central Index Key	1,393,020
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		13,401,671
Entity Public Float		$ 79,741,646

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 46,296	$ 6,048
Accounts receivable, net	3,619	2,798
Inventory	5,182	4,271
Prepaid expenses and other current assets	923	2,486
Total current assets	56,020	15,603
Restricted cash	1,090	1,125
Property and equipment, net	9,195	8,541
Other non-current assets		55
Total assets	66,305	25,324
Current liabilities:
Accounts payable	2,458	1,075
Accrued and other current liabilities	4,214	4,162
Total current liabilities	6,672	5,237
Deferred rent	2,810	2,676
Convertible preferred stock warrant liability		136
Long-term debt—related party	14,480	9,347
Total liabilities	$ 23,962	17,396
Convertible preferred stock, $0.001 par value—0 and 6,207,320 shares authorized at December 31, 2015 and 2014, respectively; 0 and 6,056,403 shares issued and outstanding at December 31, 2015 and 2014, respectively;		$ 73,755
Stockholders’ equity (deficit):
Preferred stock, $0.001 par value—10,000,000 and 0 shares authorized at December 31, 2015 and 2014, respectively; 0 shares issued and outstanding at December 31, 2015 and 2014, respectively;
Common stock, $0.001 par value—100,000,000 and 9,189,189 shares authorized at December 31, 2015 and 2014, respectively; 13,392,358 and 711,249 shares issued and outstanding at December 31, 2015 and 2014, respectively;	$ 13	$ 1
Additional paid-in capital	147,937	2,209
Accumulated deficit	(105,607)	(68,037)
Total stockholders’ equity (deficit)	42,343	(65,827)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 66,305	$ 25,324

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Convertible preferred stock, par value	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0	6,207,320
Convertible preferred stock, shares issued	0	6,056,403
Convertible preferred stock, shares outstanding	0	6,056,403
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	9,189,189
Common stock, shares issued	13,392,358	711,249
Common stock, shares outstanding	13,392,358	711,249
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Statements of Operations

Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Revenue	$ 21,031	$ 13,103	$ 7,186
Cost of goods sold	7,733	4,630	2,294
Gross profit	13,298	8,473	4,892
Operating expenses:
Research and development	7,869	5,181	4,445
Selling, general and administrative	40,636	23,044	12,402
Total operating expenses	48,505	28,225	16,847
Loss from operations	(35,207)	(19,752)	(11,955)
Interest expense (1,777, 1,052 and 0 related party interest, respectively)	(1,881)	(1,402)	(284)
Interest and other income (expense), net	(482)	492	130
Net loss	$ (37,570)	$ (20,662)	$ (12,109)
Net loss per common share, basic and diluted	$ (4.94)	$ (31.63)	$ (19.15)
Weighted-average shares used to compute net loss per common share, basic and diluted	7,606,172	653,195	632,407

Statements of Operations (Paren

Statements of Operations (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Related party interest	$ 1,777	$ 1,052	$ 0

Statements of Comprehensive Los

Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (37,570)	$ (20,662)	$ (12,109)
Other comprehensive loss:
Unrealized loss on investments			(4)
Total comprehensive loss	$ (37,570)	$ (20,662)	$ (12,113)

Statements of Convertible Prefe

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2012	$ (34,137)		$ 1	$ 1,124	$ 4	$ (35,266)
Beginning balance at Dec. 31, 2012		$ 52,949
Beginning balance, shares at Dec. 31, 2012			632,486
Beginning balance, shares at Dec. 31, 2012		4,458,589
Exercise of common stock options	65			65
Exercise of common stock options, shares			23,698
Stock-based compensation expense	279			279
Unrealized loss on investments	(4)				$ (4)
Net loss	(12,109)					(12,109)
Ending balance at Dec. 31, 2013	(45,906)		$ 1	1,468		(47,375)
Ending balance at Dec. 31, 2013		$ 52,949
Ending balance, shares at Dec. 31, 2013			656,184
Ending balance, shares at Dec. 31, 2013		4,458,589
Issuance of convertible preferred stock, net of issuance costs		$ 20,806
Issuance of convertible preferred stock, net of issuance costs, shares		1,597,814
Exercise of common stock options	78			78
Exercise of common stock options, shares			55,065
Stock-based compensation expense	663			663
Net loss	(20,662)					(20,662)
Ending balance at Dec. 31, 2014	(65,827)		$ 1	2,209		(68,037)
Ending balance at Dec. 31, 2014	$ 73,755	$ 73,755
Ending balance, shares at Dec. 31, 2014	711,249		711,249
Ending balance, shares at Dec. 31, 2014	6,056,403	6,056,403
Issuance of convertible preferred stock, net of issuance costs		$ 22,769
Issuance of convertible preferred stock, net of issuance costs, shares		1,596,212
Conversion of Convertible Preferred Stock upon IPO	$ 96,524	$ (96,524)	$ 8	96,516
Conversion of Convertible Preferred Stock upon IPO, shares		(7,652,615)	7,979,332
Conversion of preferred stock warrants to common stock warrants	608			608
Proceeds from issuance of common stock, net	47,219		$ 4	47,215
Proceeds from issuance of common stock, net, shares			4,600,000
Exercise of common stock options	$ 139			$ 139
Exercise of common stock options, shares	102,250		102,250
Repurchase of early exercised options	(1)		(473)	(1)
Vesting of early exercise options	$ 2			$ 2
Stock-based compensation expense	1,249			1,249
Net loss	(37,570)					(37,570)
Ending balance at Dec. 31, 2015	$ 42,343		$ 13	$ 147,937		$ (105,607)
Ending balance, shares at Dec. 31, 2015	13,392,358		13,392,358
Ending balance, shares at Dec. 31, 2015	0

Statements of Convertible Pref8

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Convertible preferred stock, par value	$ 0.001	$ 0.001
Common Stock [Member]
Net of stock issuance costs	$ 7,988
Series E Convertible Preferred Stock [Member]
Convertible preferred stock, par value		$ 13.3052
Net of stock issuance costs		$ 454
Series F Convertible Preferred Stock [Member]
Convertible preferred stock, par value	$ 14.3449
Net of stock issuance costs	$ 128

Statement of Cash Flows

Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities
Net loss	$ (37,570)	$ (20,662)	$ (12,109)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,710	344	227
Stock-based compensation	1,249	663	279
Changes in fair value of convertible preferred stock warrant liability	472	(522)	(168)
Provision for (recovery of) doubtful accounts	216	87	(1)
Noncash interest expense	143	90	68
Accretion of premium on marketable securities		243	191
Changes in operating assets and liabilities
Accounts receivable	(1,033)	(1,384)	(677)
Inventory	(911)	(786)	(2,384)
Prepaid expenses and other current assets	1,568	(1,923)	(177)
Other non-current assets		(55)
Accounts payable	1,349	143	413
Accrued and other current liabilities	1,537	1,034	441
Deferred rent	105	2,910
Net cash used in operating activities	(31,165)	(19,818)	(13,897)
Cash flows from investing activities
Purchases of property and equipment	(3,748)	(6,791)	(468)
Purchases of marketable securities		(17,510)	(2,156)
Sales of marketable securities		17,270
Maturities of marketable securities		850	18,120
Change in restricted cash	35	(1,090)
Net cash (used in) provided by investing activities	(3,713)	(7,271)	15,496
Cash flows from financing activities
Proceeds from issuance of long-term debt, net of issuance costs			2,500
Proceeds from issuance of long-term debt -related party, net of issuance costs	5,000	9,800
Payments of long-term debt		(2,500)	(3,016)
Proceeds from issuance of common stock upon exercise of stock options	139	78	65
Payments to repurchase early exercised common stock	(1)
Proceeds from issuance of convertible preferred stock, net of issuance costs	22,769	20,806
Proceeds from issuance of common stock upon Initial Public Offering, net of issuance costs	47,219
Net cash provided by (used in) financing activities	75,126	28,184	(451)
Net increase in cash and cash equivalents	40,248	1,095	1,148
Cash and cash equivalents, beginning of year	6,048	4,953	3,805
Cash and cash equivalents, end of year	46,296	6,048	4,953
Supplemental disclosures of cash flow information
Interest paid		275	165
Interest paid to related party	1,740	1,052
Non-cash investing and financing activities
Purchases of property and equipment in accounts payable and accrued liabilities	78	1,462	$ 31
Initial public offering costs in accounts payable and accrued liabilities		$ 30
Reclassification of preferred stock to warrant liability to additional paid in capital	608
Conversion of convertible preferred stock into common stock and additional paid in capital	$ 96,524

Organization and Description of

Organization and Description of Business	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Organization and Description of Business	1. ORGANIZATION AND DESCRIPTION OF BUSINESS Invuity, Inc. (the “Company”), was incorporated in the state of California on November 29, 2004 and reincorporated in Delaware in May 2015. The Company is a commercial-stage medical technology company which utilizes its proprietary Intelligent Photonics technology to develop single-use and reusable illuminated surgical devices, which provide surgeons with illumination and direct visualization of surgical cavities during open minimally invasive and minimal access procedures. The Company’s facilities are located in San Francisco, California. Reverse Stock Split In May 2015, the Company’s board of directors and its stockholders approved an amendment to the Company’s amended and restated articles of incorporation to effect a reverse split of shares of the Company’s common stock on a 1-for-18.5 basis (the “Reverse Stock Split”). All authorized, issued and outstanding shares of common stock, convertible preferred stock, warrants for common stock and preferred stock, options to purchase common stock and the related per share amounts contained in the financial statements have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. The Reverse Stock Split was effected on May 27, 2015. Initial Public Offering In June 2015, the Company completed an initial public offering (“IPO”) of its common stock. In connection with its IPO, the Company sold 4,600,000 shares of common stock at $12.00 per share for aggregate net proceeds of $47.2 million after underwriting discounts and commissions and offering costs incurred by the Company. These amounts include the exercise in full by the underwriters of their option to purchase up to 600,000 additional shares of common stock at the same price to cover over-allotments. Upon the closing of the IPO, all shares of convertible preferred stock then outstanding converted into 7,979,332 shares of common stock. Upon the effectiveness of the Amended and Restated Certificate of Incorporation of the Company on June 18, 2015, the number of shares of capital stock the Company is authorized to issue was increased to 110,000,000 shares, of which 100,000,000 shares are common stock and 10,000,000 shares are 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 December 31, 2015. Liquidity The Company has incurred net losses from operations since inception and has an accumulated deficit of $105.6 million as of December 31, 2015. The Company expects to incur additional losses and negative cash flows for the foreseeable future. Management believes that its cash and cash equivalents at December 31, 2015 and additional borrowings available under the its accounts receivable credit facility entered into in February 2015 will provide sufficient funds to enable the Company to meet its operating plan through at least the next twelve months. However, if the Company’s anticipated operating results are not achieved in future periods, additional debt or equity financing may need to be raised, or planned expenditures may need to be reduced.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation These financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. (U.S. GAAP). Reclassifications Certain prior year amounts in the financial statements and notes thereto have been reclassified where necessary to conform to the current presentation. These reclassifications did not affect the prior period’s balance sheet, net loss or net cash used in operating activities. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, fair value of assets and liabilities, inventory, income taxes, common stock, and stock-based compensation. Actual results could differ from those estimates and assumptions. Out-of-period and Other Adjustments During the three months ended June 30, 2015, the Company recorded an out-of-period adjustment to reverse revenue that the Company had originally recorded in the fourth quarter of 2014 associated with sales to a distributor for military facilities. The correction of this error resulted in an increase to the Company’s net loss of $302,000 for the year ended December 31, 2015 and a corresponding decrease to accounts receivable. The distributor has returned the underlying inventory, and the Company has terminated the relationship with the distributor involved, and started working with a new distributor for military accounts. Management has assessed the impact of the adjustment and does not believe the amount is material to any prior period financial statements, and the impact of correcting the error in the twelve months ended December 31, 2015 is not material to those financial statements. As a result, the Company has not restated any prior period amounts. During the three months ended March 31, 2015, the Company recorded an out-of-period adjustment to increase the fair value of the convertible preferred stock warrant liability, which was incorrectly valued at December 31, 2014 due to an error in the expected term assumption. The correction of this error resulted in an increase to the Company’s net loss of $370,000 for the three months ended March 31, 2015 and a corresponding increase to the convertible preferred stock warrant liability. Management has assessed the impact of the adjustment and does not believe that the amount is material to any prior period financial statements, and the impact of correcting the error in the three months ended March 31, 2015 is not material to those financial statements and is not material to the financial statements for the year ended December 31, 2015. As a result, the Company has not restated any prior period amounts. During the three months ended March 31, 2015, the Company determined that expenses relating to research and development in 2014 had been incorrectly classified within selling, general and administrative expenses, due to an erroneous allocation of departmental expenses. The Company has revised the statement of operations for the year ended December 31, 2014 to correct the classification, which resulted in an increase to research and development expenses of $564,000, with a corresponding decrease to selling, general and administrative expenses. Management has assessed the impact of the correction and has concluded that it is not material to the previously issued statement of operations for the year ended December 31, 2014. Cash Equivalents Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less from the date of purchase. Cash equivalents consist primarily of amounts invested in money market funds. Restricted Cash Restricted cash represents a certificate of deposit held at a financial institution as collateral for the Company credit cards and a letter of credit related to the Company’s facility lease. Short-Term Investments All short-term investments are classified as “available-for-sale” and carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments in debt securities at the time of purchase and reevaluates such designation as of each balance sheet date. Unrealized gains and losses are excluded from earnings and are reported as a component of comprehensive loss. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on available-for-sale securities are included in interest and other income (expense), net, respectively, and are derived using the specific identification method for determining the cost of securities sold. Interest on available-for-sale securities is included in interest and other income (expense), net. Unrealized gains and losses and realized gains and losses on sale of short-term investments were not material for the years ended December 31, 2015, 2014 and 2013. The Company did not hold any short-term investments as of either December 31, 2015 and 2014. Accounts Receivable Accounts receivable are recorded at the invoiced amount and do not bear interest. The Company generally does not require collateral or other security in support of accounts receivable. Allowances are provided for individual accounts receivable when the Company becomes aware of a customer’s inability to meet its financial obligations, such as in the case of bankruptcy, deterioration in the customer’s operating results or change in financial position. If circumstances related to customers change, estimates of the recoverability of receivables would be further adjusted. The Company also considers broad factors in evaluating the sufficiency of its allowance for doubtful accounts, including the length of time receivables are past due, significant one-time events, creditworthiness of customers and historical experience. Account balances are charged off against the allowance after all means of collection have been exhausted and the potential for recovery is considered remote. The allowance for doubtful accounts balance was $158,000, and $98,000 as of December 31, 2015 and 2014, respectively. The Company has written off $165,000, 0, and 0 as uncollectible accounts receivables to the allowance for doubtful accounts during the twelve months ended December 31, 2015, 2014, and 2013, respectively. Fair Value of Financial Instruments Carrying amounts of the Company’s financial instruments, including cash equivalents, short-term investments, accounts receivable, and accounts payable approximate fair value due to their relatively short maturities. As of December 31, 2015 and 2014, based on Level 2 inputs and the borrowing rates available to the Company for loans with similar terms and consideration of the Company’s credit risk, the carrying value of the Company’s long-term debt approximates its fair value. Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk at December 31, 2015 and 2014 consist primarily of cash, which is held primarily by one domestic financial institution and exceeds federally insured limits, and cash equivalents. The Company manages its liquidity risk by investing in a variety of money market funds and corporate debt. This diversification of investments is consistent with the Company’s policy to maintain liquidity and ensure the ability to collect principal. All investments are made pursuant to corporate investment policy guidelines which restrict investments to issuers evaluated as creditworthy. Significant customers are those which represent 10% or more of the Company’s total revenue or net accounts receivable balance at each respective balance sheet date. For each significant customer, revenue as a percentage of total revenue and accounts receivable as a percentage of net accounts receivable are as follows: Revenue Accounts Receivable, net Year Ended December 31, December 31, 2015 2014 2015 2014 Customers: Customer A * 12 % * 12 % Customer B * * * 12 % * Less than 10% Inventory Inventories are stated at the lower of cost or market (estimated net realizable value). Cost is determined using the standard cost method, which approximates the first-in, first out basis. The Company periodically assesses the recoverability of all inventories, including raw materials and finished goods, to determine whether adjustments to the carrying value are required. Inventory that is obsolete or in excess of forecasted usage is written down to its estimated net realizable value based on assumptions about future demand and market conditions. Inventory write-downs are charged to cost of goods. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is provided using the straight-line method over the estimated useful lives of the respective assets. The estimated useful lives of the Company’s assets are as follows: Laboratory equipment 3 years Leasehold improvements Shorter of lease term or estimated life of the assets Furniture and fixtures 3 years Computer equipment and software 2 to 3 years Manufacturing equipment 5 years Maintenance and repairs that do not extend the life or improve the asset are expensed when incurred. Impairment of Long-Lived Assets The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset (or asset group) may not be recoverable. An impairment loss is recognized when the total of estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition is less than its carrying amount. Impairment, if any, would be assessed using discounted cash flows or other appropriate measures of fair value. The Company has not recorded impairment charges on long-lived assets for the periods presented in these financial statements. Convertible Preferred Stock Warrant Liability Freestanding warrants for shares that were contingently redeemable were classified as liabilities on the balance sheet at their estimated fair value because the shares underlying the warrants may obligate the Company to transfer assets to the holders at a future date under certain circumstances such as a deemed liquidation event. The warrants were subject to re-measurement at each balance sheet date and the change in fair value, if any, was recognized as interest and other income (expense), net in the statements of operations. The Company adjusted the liability for changes in fair value until the completion of its IPO, at which time all convertible preferred stock warrants were converted into warrants to purchase common stock and the liability was reclassified to additional paid-in capital. Other Comprehensive Income (Loss) Other comprehensive income (loss) represents all changes in stockholders’ equity except those resulting from distributions to stockholders. The Company’s unrealized loss on short-term available-for-sale securities represent the components of other comprehensive income (loss) that are excluded from the reported net loss and are presented in the statements of comprehensive loss. Revenue Recognition The Company’s revenue is generated from the sale of its products to hospitals and medical centers through direct sales representatives and independent sales agents. The Company recognizes revenue when all of the following criteria are met: · persuasive evidence of an arrangement exists; · the sales price is fixed or determinable; · collection of the relevant receivable is reasonably assured at the time of sale; and · delivery has occurred or services have been rendered. The Company recognizes revenue when title to the goods and risk of loss transfers to the customer, which is upon shipment of the product under the Company’s standard terms and conditions. Shipping and handling costs billed to the customer are recorded in revenue. Warranty Obligations The Company does not offer rights of return or price protection and has no post-delivery obligations other than its standard warranty which entitles the customer to return defective products for a period of one year after sale. The warranty liability was $35,000 as of December 31, 2015. Prior to 2015, there was no warranty liability. Historical warranty costs have been insignificant. Medical Device Excise Tax In March 2010 the Affordable Care Act (the ACA) was signed into law which included a deductible 2.3% excise tax on any entity that manufactures or imports medical devices offered for sale in the United States, with limited exceptions, effective January 1, 2013. Subsequently, this excise tax was suspended effective January 1, 2016. Research and Development The Company’s research and development costs are expensed as incurred. Research and development costs includes but are not limited to, payroll and personnel-related expenses, including stock-based compensation, laboratory supplies, consulting costs, and allocated facilities and information services costs. Income Taxes The Company accounts for income taxes under the asset and liability method, whereby 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. A valuation allowance is established when, in management’s estimate, it is more likely than not that the deferred tax asset will not be realized. The tax effects of the Company’s income tax positions are recognized only if they are more likely than not to be sustained based solely on the technical merits as of the reporting date. The Company considers many factors when evaluating and estimating its tax positions and benefits, which may require periodic adjustments and which may not accurately anticipate actual outcomes. Stock-based Compensation The Company measures its stock-based awards made to employees based on the estimated fair values of the awards as of the grant date using the Black-Scholes option-pricing model. Stock-based compensation expense is recognized over the requisite service period using the straight-line method and is based on the value of the portion of stock-based payment awards that is ultimately expected to vest. As such, the Company’s stock-based compensation is reduced for the estimated forfeitures at the date of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Stock-based compensation expense for options granted to non-employees as consideration for services received is measured on the date of performance at the fair value of the consideration received or the fair value of the equity instruments issued, using the Black-Scholes option-pricing model, whichever can be more reliably measured. Compensation expense for options granted to non-employees is periodically remeasured as the underlying options vest. Segment Reporting The Company manages its operations as a single operating segment for the purposes of assessing performance and making operating decisions. All of the Company’s assets are maintained in the United States. The Company derives its revenue from sales to customers in the United States, based upon the billing address of the customer. Net Loss per Common Share Basic net loss per common share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per common share is the same as basic net loss per common share since the effect of potentially dilutive securities are anti-dilutive. Shares subject to repurchase are excluded from the weighted-average shares. Recent Accounting Pronouncements In August 2014, the FASB issued ASU No. 2014-15, Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern In July 2015, the FASB issued ASU No. 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory In April 2015, the FASB issued ASU No. 2015-03, Interest—Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs In August 2015, the FASB issued ASU No. 2015-15, Interest—Imputation of Interest (Subtopic 835-30): Presentation and Subsequent Measurement of Debt Issuance Costs Associated With Line-of-Credit Arrangements—Amendments to SEC Paragraphs Pursuant to Staff Announcement at June 18, 2015 EITF Meeting In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) Revenue Recognition Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date In November 2015, the FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes The Company has elected to early adopt ASU 2015-17 as of the beginning of our fourth quarter ended December 31, 2015 on a prospective basis. There was no impact to the Company’s balance sheet as a result of the early adoption. In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities In February 2016, the FASB issued ASU 2016-02 - Leases Leases

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. FAIR VALUE MEASUREMENTS The Company discloses and recognizes the fair value of its assets and liabilities using a hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The hierarchy gives the highest priority to valuations based upon unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to valuations based upon unobservable inputs that are significant to the valuation (Level 3 measurements). The guidance establishes three levels of the fair value hierarchy 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 market 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 financial instruments consist of Level 1 and 2 assets and Level 3 liabilities. Where quoted prices are available in an active market, securities are classified as Level 1. Level 1 assets consist primarily of highly liquid money market funds that are included in cash, cash equivalents, and restricted cash. At December 31, 2014, the Company’s Level 3 liabilities consist of the convertible preferred stock warrant liability. The determination of the fair value of the convertible preferred stock warrant liability is discussed in Note 8. Generally, increases or decreases in the fair value of the underlying convertible preferred stock would result in a directionally similar impact in the fair value measurement of the warrant liability. The following table sets forth the fair value of the Company’s financial assets and liabilities measured at fair value on a recurring basis based on the three-tier fair value hierarchy (in thousands): December 31, 2015 Level 1 Level 2 Level 3 Total Assets Money market funds $ 44,750 $ — $ — $ 44,750 $ 44,750 $ — $ — $ 44,750 December 31, 2014 Level 1 Level 2 Level 3 Total Assets Money market funds (a) $ 5,678 $ — $ — $ 5,678 $ 5,678 $ — $ — $ 5,678 Liabilities Convertible preferred stock warrant liability $ — $ — $ 136 $ 136 $ — $ — $ 136 $ 136 The following table sets forth a summary of the changes in the fair value of the convertible preferred stock warrant liability, the Company’s Level 3 financial liability, which is measured on a recurring basis (in thousands): 2015 2014 Beginning balance $ 136 $ 86 Issuance of convertible preferred stock warrants — 572 Change in fair value recorded in interest and other income (expense), net (136 ) (522 ) Ending balance $ - $ 136

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Components	4. BALANCE SHEET COMPONENTS Inventory Inventory consisted of the following (in thousands): December 31, 2015 2014 Raw materials $ 1,000 $ 894 Work-in-process 798 768 Finished goods 3,384 2,609 Total inventory $ 5,182 $ 4,271 Prepaid expenses and other current assets Prepaid expenses and other current assets consisted of the following (in thousands): December 31, 2015 2014 Prepaid expenses $ 907 $ 420 Tenant improvement allowance receivable — 2,064 Other 16 2 Total prepaid expenses and other current assets $ 923 $ 2,486 Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): December 31, 2015 2014 Computer equipment and software $ 1,341 $ 633 Laboratory and manufacturing equipment 1,544 816 Furniture and fixtures 1,445 1,409 Leasehold improvements 7,106 6,541 Total property and equipment, gross 11,436 9,399 Less: accumulated depreciation and amortization (2,241 ) (858 ) Total property and equipment, net $ 9,195 $ 8,541 Depreciation and amortization expense was $1.7 million, $0.3 million, and $0.2 million during the years ended December 31, 2015, 2014, and 2013 respectively. Accrued and Other Current Liabilities Accrued and other current liabilities consisted of the following (in thousands): December 31, 2015 2014 Accrued payroll-related expenses $ 3,052 $ 1,599 Accrued independent sales agent commissions 158 227 Accrued professional fees 373 89 Accrued costs for property and equipment — 1,453 Accrued sales and marketing expenses 45 95 Deferred rent, current 261 290 Other 325 409 Total accrued and other current liabilities $ 4,214 $ 4,162

Related Party Loan Agreement

Related Party Loan Agreement	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Related Party Loan Agreement	5. RELATED PARTY LOAN AGREEMENT In February 2014, the Company entered into a loan agreement with HealthCare Royalty Partners (“HCRP”), a related party due to its equity ownership interest in the Company, and drew down the first tranche of $10.0 million. The second tranche associated with HCRP, of $5.0 million, was drawn down in March 2015. Interest is payable quarterly at a fixed rate of 12.5% per annum with interest-only payments to be made from the effective date of the loan until March 31, 2017. Thereafter, the Company will make principal and interest payments until the maturity of the loan on December 31, 2020. The Company is permitted to make a voluntary prepayment in full, but not in part, prior to December 31, 2020, which prepayment must be made together with accrued and unpaid fixed interest on the amount prepaid and any additional amounts due in respect thereof, including an additional percentage of the aggregate loan amount or outstanding principal amount, depending on the date of prepayment. The Company’s obligations under the loan agreement are secured by a first priority security interest in all of the Company’s assets, other than bank accounts, accounts receivable and inventory. The loan agreement imposes customary affirmative and restrictive covenants, including with respect to fundamental transactions, the incurrence of additional indebtedness or liens and the payment of cash dividends, but does not include any financial covenants. The loan agreement contains a material adverse event clause which provides that an event of default will occur if, among other triggers, there occurs any circumstance that could reasonably be expected to result in a material adverse effect on the Company’s business, operations or condition, or on the Company’s ability to perform its obligations under the loan. The Company recorded interest expense of $1.8 million and $1.1 million on the loan, for the year ending December 31, 2015 and 2014, respectively. As of December 31, 2015 and 2014, management does not believe that it is probable that the clause will be triggered within the next twelve months, and therefore the debt is classified as long-term. The loan agreement also includes customary representations and warranties, events of defaults and termination provisions. As of December 31, 2015 and 2014, the Company was in compliance with all covenants. In connection with the loan agreement, the Company issued HCRP a warrant to purchase 84,553 shares of Series E convertible preferred stock at $13.3052 per share. The warrant was recorded on the balance sheet on the date of issuance at its fair value of $572,000 and recorded as a reduction in the carrying value of the debt. Upon completion of the IPO in June 2015, this warrant automatically converted into a warrant to purchase shares of common stock and the liability was reclassified to additional paid-in capital. Future payments due under the Company’s loan agreements as of December 31, 2015 are as follows (in thousands): Year ending December 31 2016 1,874 2017 3,305 2018 4,547 2019 5,601 Thereafter 6,469 21,796 Less: Amount representing interest (6,796 ) Less: Amount representing debt discount (520 ) $ 14,480

Debt

Debt	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Debt	6. DEBT In December 2010, the Company entered into a loan and security agreement with Silicon Valley Bank (“SVB”) whereby the Company may borrow funds via a series of term loans. In July 2013, the Company entered into the first amendment to the loan and security agreement with SVB. The Company repaid the outstanding balance of $1.9 million on the original loan, including accrued interest, and drew down a new term loan (“Tranche III”) in the amount of $2.5 million. Pursuant to the Tranche III loan agreement, the Company made interest-only payments at a stated rate of 6% per annum for the first eleven months from the funding date. Thereafter, the Company was obligated to pay monthly cash payments of principal and interest for a 30-month period with a balloon payment at maturity which was accreted as interest expense over the term of the loan. The Company was subject to a prepayment penalty equal to 2% of the outstanding principal amount at the prepayment date if the loan was prepaid on or before 18 months after its funding date. The loan balance of $ 2.7 million In connection with Tranche III, in July 2013, the Company granted SVB a warrant to purchase 11,294 shares of Series D convertible preferred stock at $12.395 per share. The warrant was recorded on the balance sheet on the date of issuance at its fair value of $23,000 and recorded as a reduction in the carrying value of the debt. This debt discount was initially amortized to interest expense over the term of the agreement, resulting in an effective interest rate of approximately 13.3% per annum, until the repayment of Tranche III in February 2014 at which time the remaining unamortized balance of the debt discount of $19,000 was recognized in interest expense, together with a prepayment penalty of $50,000 and the unamortized portion of the balloon interest payment of $143,000. Upon completion of the IPO on June 2016, all convertible preferred warrants automatically converted into warrants to purchase shares of common stock and the liability was reclassified to additional paid-in capital. In February 2015, the Company entered into an accounts receivable credit facility with Silicon Valley Bank (SVB) that permits the borrowing of the lesser of $7.5 million or an amount representing up to 80% of eligible accounts receivable. The credit facility matures in February 2018 and the Company’s obligations under the credit facility are secured by a first priority security interest in the Company’s bank accounts, accounts receivable, and inventory. Interest on borrowed amounts is payable monthly at the prime rate plus 0.75%. The credit facility imposes cusomary affirmative and restrictive covenants, including with respect to fundamental transactions, changes to the Company’s business, the incurrence of additional indebtedness or liens and the payment of dividends, but does not include any financial covenants. In addition, the credit facility states that if the Company maintains a net cash balance, defined as unrestricted cash held with SVB less any borrowings on the revolving line of credit, of more than $3.0 million, then all collections will be deposited in the Company’s operating account. If the net cash balance is below $3.0 million, then all collections will be held in an SVB-controlled account and applied to reduce the loan balance. The credit facility also includes customary representations and warranties, events of defaults and termination provisions. As of December 31, 2015, the Company has not drawn down on the credit facility.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. COMMITMENTS AND CONTINGENCIES Operating Leases The Company leases manufacturing and office space in San Francisco, California, under a non-cancelable operating lease entered into in May 2014. The lease commencement date was November 1, 2014 and the lease expires on October 31, 2024. At the inception of the lease, the Company provided the landlord with a security deposit of $1.1 million in the form of an irrevocable letter of credit, which was recorded in restricted cash on the balance sheet at both December 31, 2015 and December 31, 2014. Rent expense is recognized on a straight-line basis over the term of the leases and accordingly, the Company records the difference between cash rent payments and the recognition of rent expense as a deferred rent liability. Incentives granted under the Company’s facilities leases, including allowances to fund leasehold improvements, are deferred and are recognized as adjustments to rental expense on a straight-line basis over the term of the lease. The Company is entitled to a $2.6 million tenant allowance in connection with the lease entered into in November 2014. The Company has utilized the entire $2.6 million allowance in connection with the qualified costs as of December 31, 2014 and was fully reimbursed by the landlord as of December 31, 2015. The allowance has been recorded in our balance sheet as a leasehold improvement and is being amortized over the term of the lease as a reduction to rent expense. The following table summarizes the Company’s future minimum lease payments as of December 31, 2015 (in thousands): Year ending December 31: 2016 $ 2,053 2017 2,114 2018 2,178 2019 2,243 2020 2,310 Thereafter 9,511 Total $ 20,409 The Company’s rent expense was $2.0 million, $0.6 million and $0.3 million for the years ended December 31, 2015, 2014 and 2013, respectively. Legal Proceedings From time to time, the Company may become involved in legal proceedings arising from the ordinary course of its business. Management is currently not aware of any matters that will have a material adverse effect on the financial position, results of operations or cash flows of the Company. Indemnifications In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless and defend an indemnified party for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third-party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. The Company has never incurred material costs to defend lawsuits or settle claims related to these indemnification provisions. The Company has also entered into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers to the fullest extent permitted by Deleware corporate law. The Company currently has directors’ and officers’ insurance. To date, the Company has not paid any claims, and the Company believes that the estimated fair value of these indemnification obligations is minimal and it has not accrued any amounts for these obligations.

Warrants

Warrants	12 Months Ended
	Dec. 31, 2015
Text Block [Abstract]
Warrants	8. WARRANTS Common Stock Warrants In March 2010, the Company issued a warrant to purchase 3,532 shares of common stock at an exercise price of $1.30 per share to a third party in exchange for recruiting services. The Company recorded the warrants in equity at their fair value of $3,000 on the date of issuance using the Black-Scholes option-pricing model. The warrant was fully exercisable upon grant and expired upon our initial public offering in June 2015. Preferred Stock Warrants In conjunction with various financings between 2008 and 2014, the Company issued warrants to purchase 130,540 shares of convertible preferred stock. The relative fair value of these warrants was determined using the Black-Scholes model and was amortized to interest expense over the term of each loan, unless subsequently modified. All convertible preferred stock warrants were classified as liabilities on the balance sheet at their estimated fair value because the shares underlying the warrants could obligate the Company to transfer assets to the holders at a future date under certain circumstances such as a deemed liquidation event. The warrants were subject to re-measurement at each balance sheet date and the change in fair value, if any, was recognized as interest and other income, net in the statements of operations and comprehensive loss. The Company adjusted the liability for changes in fair value until the completion of its IPO, at which time all convertible preferred stock warrants were converted into warrants to purchase common stock and the liability was reclassified to additional paid-in capital. The Company recorded a (loss) / gain of $(472,000), $522,000 and $168,000 during the years ended December 31, 2015, 2014, and 2013, respectively, relating to the change in fair value of the convertible preferred stock warrant liability.

Convertible Preferred Stock and

Convertible Preferred Stock and Stockholders' Deficit	12 Months Ended
	Dec. 31, 2015
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock and Stockholders' Deficit	9. CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ DEFICIT Convertible Preferred Stock In February and March 2015, the Company issued an aggregate of 1,596,212 shares of Series F convertible preferred stock. Upon the closing of the Company’s IPO in June 2015, all 7,652,615 shares of convertible preferred stock then outstanding converted into 7,979,332 shares of common stock, which includes an aggregate of 326,717 additional shares of common stock related to anti-dilution adjustments upon conversion of the convertible preferred stock.

Stock Option Plans

Stock Option Plans	12 Months Ended
	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Option Plans	10. STOCK OPTION PLANS In April 2015, the Company’s board of directors approved the 2015 Equity Incentive plan (“2015 Plan”), effective June 11, 2015, covering incentive stock options (“ISOs”), nonstatutory stock options (“NSOs”), restricted stock, restricted stock awards (“RSU”), stock appreciation rights and performance units that may be granted to employees, directors and consultants. In connection with the approval of the 2015 Plan, all remaining shares available for future award under the 2005 Stock Option Plan (the “2005 Plan”) were transferred to the 2015 Plan, and the 2005 Plan was terminated. The number of shares initially authorized for issuance under the 2015 Plan was 1,494,272 plus 169,529 shares remaining available for future awards under the Company’s 2005 Plan. Any options under the 2005 Plan or 2015 Plan (collectively “the Plans”) that expire or otherwise terminate will revert to the 2015 Plan and again become available for issuance. The number of shares available for issuance under the 2015 Plan will be increased on the first day of each fiscal year in an amount equal to the lessor of (i) 1,494,272 shares; (ii) five percent of the outstanding shares on the last day of the immediately preceding fiscal year or (iii) such number of shares determined by the Company’s board of directors. ISOs may be granted to employees or directors holding more than 10% of the voting power of all classes of stock of the Company at an exercise price of no less than 110% of the fair value of the common stock on the grant date and to all other employees or directors at an exercise price of no less than 100% of the fair value of the common stock on the grant date. NSOs may be granted to employees, directors and consultants at an exercise price no less than 100% of the fair value of the common stock on the grant date. Employee stock options under the 2015 plan generally vest 20% upon one year of continued service to the Company, with the remainder in monthly increments over four additional years. Options expire no more than ten years after the date of grant. The Company’s Board of Directors and stockholders previously approved the 2005 Plan. Pursuant to the 2005 plan, options and restricted stock may be granted to employees, directors and consultants of the Company. Options granted under the Company’s 2005 plan may be either incentive stock options or nonstatutory stock options. ISOs may be granted to employees with exercise prices of no less than 100% the fair value of the common stock on the grant date and NSOs may be granted to employees, directors or consultants at exercise prices of no less than 85% of the fair value of the common stock on the grant date, as determined by the Board of Directors. All options granted under the 2005 plan may be exercised before they are vested. Employee stock options granted under the 2005 plan generally vest 25% upon one year of continued service to the Company, with the remainder in monthly increments over three additional years. Stock options granted to consultants generally vest over the performance period of the consultancy agreement, ranging from two to four years. Options expire no more than ten years after the date of grant. As of December 31, 2015, there were 3,445,228 shares authorized for issuance under the Plans of which 1,406,439 were available for grant. In the event of stock splits and stock dividends, the Board of Directors may increase or decrease proportionately the number of shares and the exercise (purchase) price per share deliverable to the 2015 Plan participants. In the event of a merger in which the Company is not the surviving entity or sale of substantially all the Company’s assets, all outstanding options must be either assumed or substituted by the surviving corporation, or may be required to be exercised or settled. The following table summarizes stock option activity and related information: Options Outstanding Options Available for Grant Options Outstanding Weighted- Average Exercise Price Per Share Aggregate Intrinsic Value (in thousands) Balances at December 31, 2014 315,876 1,379,503 $ 2.57 $ 9,483 Options authorized 1,852,097 — Options granted (865,976 ) 865,976 $ 12.57 Options exercised — (102,250 ) $ 1.39 Options forfeited 104,442 (104,442 ) $ 6.17 Balances at December 31, 2015 1,406,439 2,038,787 $ 6.69 $ 7,504 Options exercisable—December 31, 2015 975,314 $ 3.28 $ 5,660 Options vested and expected to vest—December 31, 2015 1,929,208 $ 6.42 $ 7,409 The intrinsic value is the difference between the estimated fair value of the Company’s common stock at the date of exercise and the exercise price for in-the-money options. The aggregate intrinsic value of options exercised was $796,000, 310,000, and $24,000 for the years ended December 31, 2015, 2014, and 2013 respectively. The weighted-average grant-date fair value of options granted during the years ended December 31, 2015, 2014 and 2013 was $4.82, $5.99, and $4.32 per share, respectively. As of December 31, 2015 and 2014, the weighted-average remaining contractual life of options outstanding was 7.8 years and for options vested and expected to vest, was 7.7 years, respectively. The options outstanding, vested and currently exercisable by exercise price under the 2015 Plan at December 31, 2015 are as follows: Options Outstanding Options Exercisable Exercise Price Number of Options Weighted- Average Remaining Contractual Life (years) Weighted- Average Exercise Price Per Share Number of Options Weighted- Average Exercise Price Per Share $ 1.30 300,733 4.7 $ 1.30 300,733 $ 1.30 $1.48-2.78 71,748 6.0 $ 2.01 68,343 $ 1.98 $ 3.15 831,426 7.5 $ 3.15 510,397 $ 3.15 $4.81-11.09 107,818 9.5 $ 10.23 19,504 $ 8.39 $ 11.10 336,160 9.1 $ 11.10 63,991 $ 11.10 $11.96-14.25 241,218 9.8 $ 13.54 770 $ 12.49 $ 15.91 149,686 9.4 $ 15.91 11,576 $ 15.91 2,038,789 7.8 $ 6.69 975,314 $ 3.28 Early Exercise of Stock Options The 2005 Plan allowed for the granting of options that may be exercised before the options have vested. Shares issued as a result of early exercise that have not vested are subject to repurchase by the Company upon termination of the purchaser’s employment or services, at the price paid by the purchaser. The Company’s right to repurchase these shares generally lapses 1/48 of the original grant date amount per month over four years. At December 31, 2015 and 2014, there were 8,648 and 17,566 shares of common stock outstanding, respectively, subject to the Company’s right of repurchase at a weighted-average price of $2.49 and $2.34 per share, respectively. Employee Stock-Based Compensation Stock-based compensation expense recognized during the years ended December 31, 2015, 2014, and 2013, includes compensation expense for stock-based awards granted to employees based on the grant date fair value of $1.1 million, $0.6 million, and $0.3 million respectively. As of December 31, 2015 and 2014, there were total unamortized compensation costs of $4.1 million and 2.0 million, respectively related to unvested stock options which the Company expects to recognize over a period of approximately 3.6 years and 3.0 years, respectively. On April 30, 2014, the Company modified the terms of 348,871 vested and unvested stock option awards by reducing their exercise price from $4.81 to $3.15 per share. There was no change in any of the other terms of the option awards. The modification resulted in an incremental value of $226,000 being allocated to the options, of which $158,000 was recognized to expense immediately based on options that were vested at the time of the modification. The remaining incremental value of $68,000 attributable to unvested shares is being recognized over their remaining vesting term of which 49,000 is still unvested as of December 31, 2015. The Company estimates the fair value of stock options using the Black-Scholes option valuation model. The fair value of employee stock options is being amortized on a straight-line basis over the requisite service period of the awards. Prior to our IPO, the fair value of the shares of the Company’s common stock underlying the stock options has historically been determined by the Company’s Board of Directors. Because there had been no public market for the Company’s common stock, its Board of Directors has determined the fair value of the Company’s common stock at the time of grant of the option by considering a number of objective and subjective factors, including the Company’s stage of development, sales of the Company’s convertible preferred stock, the Company’s operating and financial performance, equity market conditions affecting comparable public companies, the lack of liquidity of the Company’s capital stock, and the general and industry-specific economic outlooks. Since our IPO in June 2015, the fair value of our common stock is based on the closing price of our common stock, as quoted on the NASDAQ Global Market, on the date of grant. In addition to the value determined by our board and closing price on NASDAQ Global Market, the fair value is estimated using the assumptions below. Each of these inputs is subjective and its determination generally requires significant judgment. Year Ended December 31, 2015 2014 2013 Expected term (in years) 5.0 – 6.0 6.0 6.0 Expected volatility 35 – 50% 35% – 38% 43% Risk-free interest rate 1.31 – 1.89% 1.80% – 1.93% 1.08% – 1.82% Dividend yield 0% 0% 0% Expected Term. The expected term of stock-based awards represents the weighted-average period that the stock-based awards are expected to remain outstanding. The Company opted to use the “simplified method” for estimating the expected term of the awards, whereby the expected term equals the arithmetic average of the vesting term and the original contractual term of the awards. Expected Volatility. The Company determined the share price volatility for stock-based awards based on an analysis of the historical volatilities of a peer group of publicly traded medical device companies. In evaluating similarity, the Company considered factors such as industry, stage of life cycle and size. Risk-Free Interest Rate. The risk-free interest rate is based on the U.S. Treasury yield in effect at the time of the grant for zero-coupon U.S. Treasury notes with remaining terms similar to the expected term of the stock-based awards. Dividend Rate. The expected dividend was assumed to be zero as the Company has never paid dividends and has no current plans to do so. Expected Forfeiture Rate. The Company is required to estimate forfeitures at the time of grant, and revise those estimates in subsequent periods if actual forfeitures differ from those estimates. The Company uses historical data to estimate pre-vesting option forfeitures and record stock-based compensation expense only for those awards that are expected to vest. To the extent actual forfeitures differ from the estimates, the difference will be recorded as a cumulative adjustment in the period that the estimates are revised. Non-Employee Stock-Based Compensation Stock-based compensation expense related to non-employee awards was $103,000, $57,000 and $13,000 during the years ended December 31, 2015, 2014, and 2013, respectively. Total Stock-Based Compensation The following table summarizes total stock-based compensation expense for the years ended December 31, 2015, 2014, and 2013, which was included in the statements of operations as follows (in thousands): Year Ended December 31, 2015 2014 2013 Cost of goods sold $ 89 $ 23 $ 4 Selling, general and administrative 860 547 233 Research and development 300 93 42 Total stock-based compensation expense $ 1,249 $ 663 $ 279

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	11. INCOME TAXES The Company has incurred net operating losses for the years ended December 31, 2015, 2014 and 2013, therefore has no provision for income taxes recorded for such years. For the years ended December 31, 2015, 2014 and 2013, the Company generated losses before taxes in the United States of $37.6 million, $20.7 million and $12.1 million, respectively and no foreign income or losses. The Company’s deferred tax assets are offset by a full valuation allowance. The reconciliation of the statutory federal income tax rate to the Company’s effective tax rate is as follows: Year Ended December 31, 2015 2014 2013 Tax at statutory federal rate 34.0 % 34.0 % 34.0 % State taxes, net of federal benefit 0.4 3.8 4.9 Tax credits 0.9 1.3 1.0 Change in valuation allowance (33.9 ) (37.8 ) (40.1 ) Other (1.4 ) (1.3 ) 0.2 Provision for income taxes 0.0 % 0.0 % 0.0 % The tax effects of temporary differences and carryforwards that give rise to significant portions of the deferred tax assets are as follows (in thousands): December 31, 2015 2014 2013 Deferred tax assets: Net operating loss carryforwards $ 35,474 $ 23,574 $ 17,364 Research and development 986 782 626 Accrued liabilities and other 935 590 509 Stock-based compensation 485 259 194 Fixed assets 219 100 95 Tenant improvement allowance 836 970 — Total deferred tax assets 38,935 26,275 18,788 Valuation allowance (38,935 ) (26,275 ) (18,788 ) Net deferred tax assets $ — $ — $ — Realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $12.7million, $7.5 million and $4.9 million for the years ended December 31, 2015, 2014 and 2013, respectively, and there were no releases of the valuation allowance in these years. As of December 31, 2015, the Company had net operating loss (“NOL”) carryforwards (before tax effects) for federal and state income tax purposes of $95.2 million and $60.9 million, respectively. These federal and state NOL carryforwards will begin to expire in 2026 and 2017, respectively, if not utilized. In addition, the Company has federal and state research and development tax credit carryforwards of $0.7 million and $0.9 million, respectively, to offset future income tax liabilities. The federal research and development tax credits will begin to expire in 2024, if not utilized, while the state research and development tax credit can be carried forward indefinitely. Federal and California tax laws impose substantial restrictions on the utilization of net operating losses and credit carry-forwards in the event of an “ownership change” for tax purposes, as defined in Section 382 of the Internal Revenue Code. Due to ownership changes since inception, the Company’s net operating losses may be limited as to their usage. In the event the Company has additional changes in ownership, utilization of the carryforwards could be further restricted. A reconciliation of the Company’s unrecognized tax benefits for the years ended December 31, 2015, 2014, and 2013 is as follows (in thousands): Year Ended December 31, 2015 2014 2013 Balance at beginning of year $ 261 $ 209 $ 157 Additions for tax positions taken in current year 86 69 52 Reductions for tax positions taken in prior years (18 ) (17 ) — Balance at end of year $ 329 $ 261 $ 209 The unrecognized tax benefits, if recognized, would not have an impact on the Company’s effective tax rate to the extent that the Company continues to maintain a full valuation allowance against its deferred tax assets. The Company does not expect a material change to its unrecognized tax benefits over the next 12 months. The Company’s policy is to include interest and penalties related to unrecognized tax benefits within the provision for income taxes. Management determined that no accrual for interest and penalties was required as of December 31, 2015 and 2014, respectively. The Company’s tax years 2005-2014 will remain open for examination by the federal and state authorities for three and four years, respectively, from the date of utilization of any NOL or research and development credits.

Net Loss per Common Share

Net Loss per Common Share	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Net Loss per Common Share	12. NET LOSS PER COMMON SHARE The following table sets forth the computation of the basic and diluted net loss per share during the years ended December 31, 2015, 2014, and 2013 (in thousands, except share and per share data): Year Ended December 31, 2015 2014 2013 Numerator: Net loss $ (37,570 ) $ (20,662 ) $ (12,109 ) Denominator: Weighted-average common shares outstanding 7,619,696 673,573 633,146 Less: weighted-average unvested common shares subject to repurchase (13,524 ) (20,378 ) (739 ) Weighted-average shares used to compute net loss per common share, basic and diluted 7,606,172 653,195 632,407 Net loss per common share, basic and diluted $ (4.94 ) $ (31.63 ) $ (19.15 ) Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares and potentially dilutive securities outstanding for the period, determined using the treasury-stock method and the as-if converted method, for convertible securities, if inclusion of these is dilutive. Because the Company has reported a net loss for all periods presented, diluted net loss per common share is the same as basic net loss per common share for those periods. The following potentially dilutive securities outstanding at the end of the periods presented have been excluded from the computation of diluted shares outstanding: Years ended December 31, 2015 2014 2013 Convertible preferred stock on an as-converted basis — 6,246,196 4,648,382 Options to purchase common stock 2,038,789 1,379,503 911,403 Warrants to purchase common stock 137,007 3,532 3,532 Warrants to purchase convertible preferred stock on an as-converted basis — 134,570 50,017 Total 2,175,796 7,763,801 5,613,334

Selected Quarterly Information

Selected Quarterly Information (Unaudited)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Information (Unaudited)	SUPPLEMENTARY FINANCIAL DATA (unaudited) The following table presents selected unaudited consolidated financial data for each of the eight quarters in the two-year period ended December 31, 2015. The selected quarterly financial data should be read in conjunction with the Company's consolidated financial statements and the related notes and "Item 7: Management's Discussion and Analysis of Financial Condition and Results of Operations." This information has been derived from the Company's unaudited consolidated financial statements that, in management's opinion, reflect all recurring adjustments necessary to fairly state this information when read in conjunction with the Company's financial statements and the related notes appearing in the section entitled " Financial Statements," Net loss per share-basic and diluted, for the four quarters of each fiscal year may not sum to the total for the fiscal year because of the different number of shares outstanding during each period. The results of operations for any quarter are not necessarily indicative of the results to be expected for any future period. Three Months Ended December 31, 2015 September 30, 2015 June 30, 2015 March 31, 2015 Revenue $ 6,246 $ 5,595 $ 4,748 $ 4,442 Gross profit 4,119 3,561 2,898 2,720 Loss from operations (9,567 ) (8,661 ) (8,866 ) (8,113 ) Net loss $ (10,055 ) $ (9,138 ) $ (9,346 ) $ (9,031 ) Net loss per common share, basic and diluted $ (0.76 ) $ (0.69 ) $ (3.20 ) $ (12.84 ) Weighted-average shares used to compute net loss per common share, basic and diluted 13,307,031 13,292,849 2,919,823 703,637 Three Months Ended December 31, 2014 September 30, 2014 June 30, 2014 March 31, 2014 Revenue $ 4,409 $ 3,724 $ 2,817 $ 2,153 Gross profit 3,010 2,430 1,588 1,445 Loss from operations (5,348 ) (4,920 ) (5,112 ) (4,371 ) Net loss $ (5,203 ) $ (5,290 ) $ (5,456 ) $ (4,713 ) Net loss per common share, basic and diluted $ (7.78 ) $ (8.11 ) $ (8.40 ) $ (7.34 ) Weighted-average shares used to compute net loss per common share, basic and diluted 669,202 651,959 649,511 641,810

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation These financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. (U.S. GAAP).
Reclassifications	Reclassifications Certain prior year amounts in the financial statements and notes thereto have been reclassified where necessary to conform to the current presentation. These reclassifications did not affect the prior period’s balance sheet, net loss or net cash used in operating activities.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, fair value of assets and liabilities, inventory, income taxes, common stock, and stock-based compensation. Actual results could differ from those estimates and assumptions.
Out-of-period And Other Adjustments	Out-of-period and Other Adjustments During the three months ended June 30, 2015, the Company recorded an out-of-period adjustment to reverse revenue that the Company had originally recorded in the fourth quarter of 2014 associated with sales to a distributor for military facilities. The correction of this error resulted in an increase to the Company’s net loss of $302,000 for the year ended December 31, 2015 and a corresponding decrease to accounts receivable. The distributor has returned the underlying inventory, and the Company has terminated the relationship with the distributor involved, and started working with a new distributor for military accounts. Management has assessed the impact of the adjustment and does not believe the amount is material to any prior period financial statements, and the impact of correcting the error in the twelve months ended December 31, 2015 is not material to those financial statements. As a result, the Company has not restated any prior period amounts. During the three months ended March 31, 2015, the Company recorded an out-of-period adjustment to increase the fair value of the convertible preferred stock warrant liability, which was incorrectly valued at December 31, 2014 due to an error in the expected term assumption. The correction of this error resulted in an increase to the Company’s net loss of $370,000 for the three months ended March 31, 2015 and a corresponding increase to the convertible preferred stock warrant liability. Management has assessed the impact of the adjustment and does not believe that the amount is material to any prior period financial statements, and the impact of correcting the error in the three months ended March 31, 2015 is not material to those financial statements and is not material to the financial statements for the year ended December 31, 2015. As a result, the Company has not restated any prior period amounts. During the three months ended March 31, 2015, the Company determined that expenses relating to research and development in 2014 had been incorrectly classified within selling, general and administrative expenses, due to an erroneous allocation of departmental expenses. The Company has revised the statement of operations for the year ended December 31, 2014 to correct the classification, which resulted in an increase to research and development expenses of $564,000, with a corresponding decrease to selling, general and administrative expenses. Management has assessed the impact of the correction and has concluded that it is not material to the previously issued statement of operations for the year ended December 31, 2014.
Cash Equivalents	Cash Equivalents Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less from the date of purchase. Cash equivalents consist primarily of amounts invested in money market funds.
Restricted Cash	Restricted Cash Restricted cash represents a certificate of deposit held at a financial institution as collateral for the Company credit cards and a letter of credit related to the Company’s facility lease.
Short-term Investments	Short-Term Investments All short-term investments are classified as “available-for-sale” and carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments in debt securities at the time of purchase and reevaluates such designation as of each balance sheet date. Unrealized gains and losses are excluded from earnings and are reported as a component of comprehensive loss. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on available-for-sale securities are included in interest and other income (expense), net, respectively, and are derived using the specific identification method for determining the cost of securities sold. Interest on available-for-sale securities is included in interest and other income (expense), net. Unrealized gains and losses and realized gains and losses on sale of short-term investments were not material for the years ended December 31, 2015, 2014 and 2013. The Company did not hold any short-term investments as of either December 31, 2015 and 2014.
Accounts Receivable	Accounts Receivable Accounts receivable are recorded at the invoiced amount and do not bear interest. The Company generally does not require collateral or other security in support of accounts receivable. Allowances are provided for individual accounts receivable when the Company becomes aware of a customer’s inability to meet its financial obligations, such as in the case of bankruptcy, deterioration in the customer’s operating results or change in financial position. If circumstances related to customers change, estimates of the recoverability of receivables would be further adjusted. The Company also considers broad factors in evaluating the sufficiency of its allowance for doubtful accounts, including the length of time receivables are past due, significant one-time events, creditworthiness of customers and historical experience. Account balances are charged off against the allowance after all means of collection have been exhausted and the potential for recovery is considered remote. The allowance for doubtful accounts balance was $158,000, and $98,000 as of December 31, 2015 and 2014, respectively. The Company has written off $165,000, 0, and 0 as uncollectible accounts receivables to the allowance for doubtful accounts during the twelve months ended December 31, 2015, 2014, and 2013, respectively.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Carrying amounts of the Company’s financial instruments, including cash equivalents, short-term investments, accounts receivable, and accounts payable approximate fair value due to their relatively short maturities. As of December 31, 2015 and 2014, based on Level 2 inputs and the borrowing rates available to the Company for loans with similar terms and consideration of the Company’s credit risk, the carrying value of the Company’s long-term debt approximates its fair value.
Customer Concentration	Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk at December 31, 2015 and 2014 consist primarily of cash, which is held primarily by one domestic financial institution and exceeds federally insured limits, and cash equivalents. The Company manages its liquidity risk by investing in a variety of money market funds and corporate debt. This diversification of investments is consistent with the Company’s policy to maintain liquidity and ensure the ability to collect principal. All investments are made pursuant to corporate investment policy guidelines which restrict investments to issuers evaluated as creditworthy. Significant customers are those which represent 10% or more of the Company’s total revenue or net accounts receivable balance at each respective balance sheet date. For each significant customer, revenue as a percentage of total revenue and accounts receivable as a percentage of net accounts receivable are as follows: Revenue Accounts Receivable, net Year Ended December 31, December 31, 2015 2014 2015 2014 Customers: Customer A * 12 % * 12 % Customer B * * * 12 % * Less than 10%
Inventory	Inventory Inventories are stated at the lower of cost or market (estimated net realizable value). Cost is determined using the standard cost method, which approximates the first-in, first out basis. The Company periodically assesses the recoverability of all inventories, including raw materials and finished goods, to determine whether adjustments to the carrying value are required. Inventory that is obsolete or in excess of forecasted usage is written down to its estimated net realizable value based on assumptions about future demand and market conditions. Inventory write-downs are charged to cost of goods.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is provided using the straight-line method over the estimated useful lives of the respective assets. The estimated useful lives of the Company’s assets are as follows: Laboratory equipment 3 years Leasehold improvements Shorter of lease term or estimated life of the assets Furniture and fixtures 3 years Computer equipment and software 2 to 3 years Manufacturing equipment 5 years Maintenance and repairs that do not extend the life or improve the asset are expensed when incurred.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset (or asset group) may not be recoverable. An impairment loss is recognized when the total of estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition is less than its carrying amount. Impairment, if any, would be assessed using discounted cash flows or other appropriate measures of fair value. The Company has not recorded impairment charges on long-lived assets for the periods presented in these financial statements.
Convertible Preferred Stock Warrant Liability	Convertible Preferred Stock Warrant Liability Freestanding warrants for shares that were contingently redeemable were classified as liabilities on the balance sheet at their estimated fair value because the shares underlying the warrants may obligate the Company to transfer assets to the holders at a future date under certain circumstances such as a deemed liquidation event. The warrants were subject to re-measurement at each balance sheet date and the change in fair value, if any, was recognized as interest and other income (expense), net in the statements of operations. The Company adjusted the liability for changes in fair value until the completion of its IPO, at which time all convertible preferred stock warrants were converted into warrants to purchase common stock and the liability was reclassified to additional paid-in capital.
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Other comprehensive income (loss) represents all changes in stockholders’ equity except those resulting from distributions to stockholders. The Company’s unrealized loss on short-term available-for-sale securities represent the components of other comprehensive income (loss) that are excluded from the reported net loss and are presented in the statements of comprehensive loss.
Revenue Recognition	Revenue Recognition The Company’s revenue is generated from the sale of its products to hospitals and medical centers through direct sales representatives and independent sales agents. The Company recognizes revenue when all of the following criteria are met: · persuasive evidence of an arrangement exists; · the sales price is fixed or determinable; · collection of the relevant receivable is reasonably assured at the time of sale; and · delivery has occurred or services have been rendered. The Company recognizes revenue when title to the goods and risk of loss transfers to the customer, which is upon shipment of the product under the Company’s standard terms and conditions. Shipping and handling costs billed to the customer are recorded in revenue.
Warranty Obligations	Warranty Obligations The Company does not offer rights of return or price protection and has no post-delivery obligations other than its standard warranty which entitles the customer to return defective products for a period of one year after sale. The warranty liability was $35,000 as of December 31, 2015. Prior to 2015, there was no warranty liability. Historical warranty costs have been insignificant.
Medical Device Excise Tax	Medical Device Excise Tax In March 2010 the Affordable Care Act (the ACA) was signed into law which included a deductible 2.3% excise tax on any entity that manufactures or imports medical devices offered for sale in the United States, with limited exceptions, effective January 1, 2013. Subsequently, this excise tax was suspended effective January 1, 2016.
Research and Development	Research and Development The Company’s research and development costs are expensed as incurred. Research and development costs includes but are not limited to, payroll and personnel-related expenses, including stock-based compensation, laboratory supplies, consulting costs, and allocated facilities and information services costs.
Income Taxes	Income Taxes The Company accounts for income taxes under the asset and liability method, whereby 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. A valuation allowance is established when, in management’s estimate, it is more likely than not that the deferred tax asset will not be realized. The tax effects of the Company’s income tax positions are recognized only if they are more likely than not to be sustained based solely on the technical merits as of the reporting date. The Company considers many factors when evaluating and estimating its tax positions and benefits, which may require periodic adjustments and which may not accurately anticipate actual outcomes.
Stock-based Compensation	Stock-based Compensation The Company measures its stock-based awards made to employees based on the estimated fair values of the awards as of the grant date using the Black-Scholes option-pricing model. Stock-based compensation expense is recognized over the requisite service period using the straight-line method and is based on the value of the portion of stock-based payment awards that is ultimately expected to vest. As such, the Company’s stock-based compensation is reduced for the estimated forfeitures at the date of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Stock-based compensation expense for options granted to non-employees as consideration for services received is measured on the date of performance at the fair value of the consideration received or the fair value of the equity instruments issued, using the Black-Scholes option-pricing model, whichever can be more reliably measured. Compensation expense for options granted to non-employees is periodically remeasured as the underlying options vest.
Segment Reporting	Segment Reporting The Company manages its operations as a single operating segment for the purposes of assessing performance and making operating decisions. All of the Company’s assets are maintained in the United States. The Company derives its revenue from sales to customers in the United States, based upon the billing address of the customer.
Net loss per Common Share	Net Loss per Common Share Basic net loss per common share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per common share is the same as basic net loss per common share since the effect of potentially dilutive securities are anti-dilutive. Shares subject to repurchase are excluded from the weighted-average shares.
Recent Accounting Pronouncements	In August 2014, the FASB issued ASU No. 2014-15, Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern In July 2015, the FASB issued ASU No. 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory In April 2015, the FASB issued ASU No. 2015-03, Interest—Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs In August 2015, the FASB issued ASU No. 2015-15, Interest—Imputation of Interest (Subtopic 835-30): Presentation and Subsequent Measurement of Debt Issuance Costs Associated With Line-of-Credit Arrangements—Amendments to SEC Paragraphs Pursuant to Staff Announcement at June 18, 2015 EITF Meeting In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) Revenue Recognition Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date In November 2015, the FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes The Company has elected to early adopt ASU 2015-17 as of the beginning of our fourth quarter ended December 31, 2015 on a prospective basis. There is no impact to the balance sheet amount as a result of the early adoption. In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities In February 2016, the FASB issued ASU 2016-02 – Leases Leases

Summary of Significant Accoun24

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Schedule of Revenue as Percentage of Total Revenue for Each Significant Customer	For each significant customer, revenue as a percentage of total revenue and accounts receivable as a percentage of net accounts receivable are as follows: Revenue Accounts Receivable, net Year Ended December 31, December 31, 2015 2014 2015 2014 Customers: Customer A * 12 % * 12 % Customer B * * * 12 % * Less than 10%
Schedule of Estimated Useful Lives of Assets	The estimated useful lives of the Company’s assets are as follows: Laboratory equipment 3 years Leasehold improvements Shorter of lease term or estimated life of the assets Furniture and fixtures 3 years Computer equipment and software 2 to 3 years Manufacturing equipment 5 years

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Measured at Fair Value on Recurring Basis Based on Three-Tier Fair Value Hierarchy	The following table sets forth the fair value of the Company’s financial assets and liabilities measured at fair value on a recurring basis based on the three-tier fair value hierarchy (in thousands): December 31, 2015 Level 1 Level 2 Level 3 Total Assets Money market funds $ 44,750 $ — $ — $ 44,750 $ 44,750 $ — $ — $ 44,750 December 31, 2014 Level 1 Level 2 Level 3 Total Assets Money market funds (a) $ 5,678 $ — $ — $ 5,678 $ 5,678 $ — $ — $ 5,678 Liabilities Convertible preferred stock warrant liability $ — $ — $ 136 $ 136 $ — $ — $ 136 $ 136
Summary of Changes in Fair Value of Convertible Preferred Stock Warrant Liability	The following table sets forth a summary of the changes in the fair value of the convertible preferred stock warrant liability, the Company’s Level 3 financial liability, which is measured on a recurring basis (in thousands): 2015 2014 Beginning balance $ 136 $ 86 Issuance of convertible preferred stock warrants — 572 Change in fair value recorded in interest and other income (expense), net (136 ) (522 ) Ending balance $ - $ 136

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Schedule of Inventory	Inventory consisted of the following (in thousands): December 31, 2015 2014 Raw materials $ 1,000 $ 894 Work-in-process 798 768 Finished goods 3,384 2,609 Total inventory $ 5,182 $ 4,271
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets Prepaid expenses and other current assets consisted of the following (in thousands): December 31, 2015 2014 Prepaid expenses $ 907 $ 420 Tenant improvement allowance receivable — 2,064 Other 16 2 Total prepaid expenses and other current assets $ 923 $ 2,486
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): December 31, 2015 2014 Computer equipment and software $ 1,341 $ 633 Laboratory and manufacturing equipment 1,544 816 Furniture and fixtures 1,445 1,409 Leasehold improvements 7,106 6,541 Total property and equipment, gross 11,436 9,399 Less: accumulated depreciation and amortization (2,241 ) (858 ) Total property and equipment, net $ 9,195 $ 8,541
Schedule of Accrued and Other Current Liabilities	Accrued and other current liabilities consisted of the following (in thousands): December 31, 2015 2014 Accrued payroll-related expenses $ 3,052 $ 1,599 Accrued independent sales agent commissions 158 227 Accrued professional fees 373 89 Accrued costs for property and equipment — 1,453 Accrued sales and marketing expenses 45 95 Deferred rent, current 261 290 Other 325 409 Total accrued and other current liabilities $ 4,214 $ 4,162

Related Party Loan Agreement (T

Related Party Loan Agreement (Tables)	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Schedule of Future Payments under Company's Loan Agreements	Future payments due under the Company’s loan agreements as of December 31, 2015 are as follows (in thousands): Year ending December 31 2016 1,874 2017 3,305 2018 4,547 2019 5,601 Thereafter 6,469 21,796 Less: Amount representing interest (6,796 ) Less: Amount representing debt discount (520 ) $ 14,480

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments And Contingencies Disclosure [Abstract]
Summary of Company's Future Minimum Lease Payments	The following table summarizes the Company’s future minimum lease payments as of December 31, 2015 (in thousands): Year ending December 31: 2016 $ 2,053 2017 2,114 2018 2,178 2019 2,243 2020 2,310 Thereafter 9,511 Total $ 20,409

Stock Option Plans (Tables)

Stock Option Plans (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Option Activity	The following table summarizes stock option activity and related information: Options Outstanding Options Available for Grant Options Outstanding Weighted- Average Exercise Price Per Share Aggregate Intrinsic Value (in thousands) Balances at December 31, 2014 315,876 1,379,503 $ 2.57 $ 9,483 Options authorized 1,852,097 — Options granted (865,976 ) 865,976 $ 12.57 Options exercised — (102,250 ) $ 1.39 Options forfeited 104,442 (104,442 ) $ 6.17 Balances at December 31, 2015 1,406,439 2,038,787 $ 6.69 $ 7,504 Options exercisable—December 31, 2015 975,314 $ 3.28 $ 5,660 Options vested and expected to vest—December 31, 2015 1,929,208 $ 6.42 $ 7,409
Schedule of Options Outstanding, Vested and Currently Exercisable by Exercise Price	The options outstanding, vested and currently exercisable by exercise price under the 2015 Plan at December 31, 2015 are as follows: Options Outstanding Options Exercisable Exercise Price Number of Options Weighted- Average Remaining Contractual Life (years) Weighted- Average Exercise Price Per Share Number of Options Weighted- Average Exercise Price Per Share $ 1.30 300,733 4.7 $ 1.30 300,733 $ 1.30 $1.48-2.78 71,748 6.0 $ 2.01 68,343 $ 1.98 $ 3.15 831,426 7.5 $ 3.15 510,397 $ 3.15 $4.81-11.09 107,818 9.5 $ 10.23 19,504 $ 8.39 $ 11.10 336,160 9.1 $ 11.10 63,991 $ 11.10 $11.96-14.25 241,218 9.8 $ 13.54 770 $ 12.49 $ 15.91 149,686 9.4 $ 15.91 11,576 $ 15.91 2,038,789 7.8 $ 6.69 975,314 $ 3.28
Schedule of Assumptions Used in Estimated Fair Value of Share-based Compensation for Options Granted	the fair value is estimated using the assumptions below. Each of these inputs is subjective and its determination generally requires significant judgment. Year Ended December 31, 2015 2014 2013 Expected term (in years) 5.0 – 6.0 6.0 6.0 Expected volatility 35 – 50% 35% – 38% 43% Risk-free interest rate 1.31 – 1.89% 1.80% – 1.93% 1.08% – 1.82% Dividend yield 0% 0% 0%
Summary of Total Stock-based Compensation Expense Included in Statements of Operations	The following table summarizes total stock-based compensation expense for the years ended December 31, 2015, 2014, and 2013, which was included in the statements of operations as follows (in thousands): Year Ended December 31, 2015 2014 2013 Cost of goods sold $ 89 $ 23 $ 4 Selling, general and administrative 860 547 233 Research and development 300 93 42 Total stock-based compensation expense $ 1,249 $ 663 $ 279

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of Reconciliation of the Statutory Federal Income Tax Rate to the Company's Effective Tax Rate	The reconciliation of the statutory federal income tax rate to the Company’s effective tax rate is as follows: Year Ended December 31, 2015 2014 2013 Tax at statutory federal rate 34.0 % 34.0 % 34.0 % State taxes, net of federal benefit 0.4 3.8 4.9 Tax credits 0.9 1.3 1.0 Change in valuation allowance (33.9 ) (37.8 ) (40.1 ) Other (1.4 ) (1.3 ) 0.2 Provision for income taxes 0.0 % 0.0 % 0.0 %
Summary of Significant Portions of the Deferred Tax Assets	The tax effects of temporary differences and carryforwards that give rise to significant portions of the deferred tax assets are as follows (in thousands): December 31, 2015 2014 2013 Deferred tax assets: Net operating loss carryforwards $ 35,474 $ 23,574 $ 17,364 Research and development 986 782 626 Accrued liabilities and other 935 590 509 Stock-based compensation 485 259 194 Fixed assets 219 100 95 Tenant improvement allowance 836 970 — Total deferred tax assets 38,935 26,275 18,788 Valuation allowance (38,935 ) (26,275 ) (18,788 ) Net deferred tax assets $ — $ — $ —
Schedule of Reconciliation of the Company's Unrecognized Tax Benefits	A reconciliation of the Company’s unrecognized tax benefits for the years ended December 31, 2015, 2014, and 2013 is as follows (in thousands): Year Ended December 31, 2015 2014 2013 Balance at beginning of year $ 261 $ 209 $ 157 Additions for tax positions taken in current year 86 69 52 Reductions for tax positions taken in prior years (18 ) (17 ) — Balance at end of year $ 329 $ 261 $ 209

Net Loss per Common Share (Tabl

Net Loss per Common Share (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Net Loss per Share	The following table sets forth the computation of the basic and diluted net loss per share during the years ended December 31, 2015, 2014, and 2013 (in thousands, except share and per share data): Year Ended December 31, 2015 2014 2013 Numerator: Net loss $ (37,570 ) $ (20,662 ) $ (12,109 ) Denominator: Weighted-average common shares outstanding 7,619,696 673,573 633,146 Less: weighted-average unvested common shares subject to repurchase (13,524 ) (20,378 ) (739 ) Weighted-average shares used to compute net loss per common share, basic and diluted 7,606,172 653,195 632,407 Net loss per common share, basic and diluted $ (4.94 ) $ (31.63 ) $ (19.15 )
Schedule of Potentially Dilutive Securities Outstanding Excluded from Computation of Diluted Shares Outstanding	The following potentially dilutive securities outstanding at the end of the periods presented have been excluded from the computation of diluted shares outstanding: Years ended December 31, 2015 2014 2013 Convertible preferred stock on an as-converted basis — 6,246,196 4,648,382 Options to purchase common stock 2,038,789 1,379,503 911,403 Warrants to purchase common stock 137,007 3,532 3,532 Warrants to purchase convertible preferred stock on an as-converted basis — 134,570 50,017 Total 2,175,796 7,763,801 5,613,334

Selected Quarterly Informatio32

Selected Quarterly Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of Selected Quarterly Information	The following table presents selected unaudited consolidated financial data for each of the eight quarters in the two-year period ended December 31, 2015. The selected quarterly financial data should be read in conjunction with the Company's consolidated financial statements and the related notes and "Item 7: Management's Discussion and Analysis of Financial Condition and Results of Operations." This information has been derived from the Company's unaudited consolidated financial statements that, in management's opinion, reflect all recurring adjustments necessary to fairly state this information when read in conjunction with the Company's financial statements and the related notes appearing in the section entitled " Financial Statements," Net loss per share-basic and diluted, for the four quarters of each fiscal year may not sum to the total for the fiscal year because of the different number of shares outstanding during each period. The results of operations for any quarter are not necessarily indicative of the results to be expected for any future period. Three Months Ended December 31, 2015 September 30, 2015 June 30, 2015 March 31, 2015 Revenue $ 6,246 $ 5,595 $ 4,748 $ 4,442 Gross profit 4,119 3,561 2,898 2,720 Loss from operations (9,567 ) (8,661 ) (8,866 ) (8,113 ) Net loss $ (10,055 ) $ (9,138 ) $ (9,346 ) $ (9,031 ) Net loss per common share, basic and diluted $ (0.76 ) $ (0.69 ) $ (3.20 ) $ (12.84 ) Weighted-average shares used to compute net loss per common share, basic and diluted 13,307,031 13,292,849 2,919,823 703,637 Three Months Ended December 31, 2014 September 30, 2014 June 30, 2014 March 31, 2014 Revenue $ 4,409 $ 3,724 $ 2,817 $ 2,153 Gross profit 3,010 2,430 1,588 1,445 Loss from operations (5,348 ) (4,920 ) (5,112 ) (4,371 ) Net loss $ (5,203 ) $ (5,290 ) $ (5,456 ) $ (4,713 ) Net loss per common share, basic and diluted $ (7.78 ) $ (8.11 ) $ (8.40 ) $ (7.34 ) Weighted-average shares used to compute net loss per common share, basic and diluted 669,202 651,959 649,511 641,810

Organization and Description 33

Organization and Description of Business - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Jun. 30, 2015USD ($)$ / sharesshares	May. 31, 2015	Dec. 31, 2015USD ($)$ / sharesshares	Jun. 18, 2015$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares
Organization And Nature Of Operations [Line Items]
Proceeds from issuance of common stock, net | $			$ 47,219
Capital stock authorized				110,000,000
Common stock, shares authorized			100,000,000	100,000,000	9,189,189
Preferred stock, shares authorized			10,000,000	10,000,000	0
Common stock, par value | $ / shares			$ 0.001	$ 0.001	$ 0.001
Preferred stock, par value | $ / shares			$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares outstanding			0		0
Accumulated deficit | $			$ 105,607		$ 68,037
Common Stock [Member]
Organization And Nature Of Operations [Line Items]
Description reverse stock split			In May 2015, the Company’s board of directors and its stockholders approved an amendment to the Company’s amended and restated articles of incorporation to effect a reverse split of shares of the Company’s common stock on a 1-for-18.5 basis (the “Reverse Stock Split”). All authorized, issued and outstanding shares of common stock, convertible preferred stock, warrants for common stock and preferred stock, options to purchase common stock and the related per share amounts contained in the financial statements have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. The Reverse Stock Split was effected on May 27, 2015
Reverse stock split ratio		0.0541
Stock issued, shares			4,600,000
Proceeds from issuance of common stock, net | $			$ 4
Convertible preferred stock converted into shares of common stock	7,979,332
Common Stock [Member] | IPO [Member]
Organization And Nature Of Operations [Line Items]
Stock issued, shares	4,600,000
Public offering price | $ / shares	$ 12
Proceeds from issuance of common stock, net | $	$ 47,218
Option to purchase additional shares	600,000
Convertible preferred stock converted into shares of common stock	7,979,332

Summary of Significant Accoun34

Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended								12 Months Ended
	Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Sep. 30, 2014USD ($)	Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2015USD ($)Segment	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 30, 2015USD ($)
Significant Accounting Policies [Line Items]
Net loss	$ (10,055,000)	$ (9,138,000)	$ (9,346,000)	$ (9,031,000)	$ (5,203,000)	$ (5,290,000)	$ (5,456,000)	$ (4,713,000)	$ (37,570,000)	$ (20,662,000)	$ (12,109,000)
Accounts receivable, net	3,619,000				2,798,000				3,619,000	2,798,000
Convertible preferred stock warrant liability					136,000					136,000
Research and development									7,869,000	5,181,000	4,445,000
Selling, general and administrative									40,636,000	23,044,000	12,402,000
Allowance for doubtful accounts balance	158,000				$ 98,000				158,000	98,000
Write off adjustments charged to allowance									165,000	0	$ 0
Warrant liability	35,000								$ 35,000			$ 0
Medical device excise tax percentage									2.30%
Number of operating segments | Segment									1
Restatement Adjustment [Member]
Significant Accounting Policies [Line Items]
Research and development										564,000
Selling, general and administrative										$ (564,000)
Error Correction [Member] | Restatement Adjustment [Member]
Significant Accounting Policies [Line Items]
Net loss									$ (302,000)
Accounts receivable, net	$ (302,000)								$ (302,000)
Convertible preferred stock warrant liability				$ 370,000

Summary of Significant Accoun35

Summary of Significant Accounting Policies - Schedule of Revenue as Percentage of Total Revenue for Each Significant Customer (Detail)	12 Months Ended
	Dec. 31, 2014
Customer A [Member] | Customer Concentration Risk [Member] | Revenue [Member]
Concentration Risk [Line Items]
Customer concentration, percentage	12.00%
Customer A [Member] | Credit Concentration Risk [Member] | Accounts Receivable, Net [Member]
Concentration Risk [Line Items]
Customer concentration, percentage	12.00%
Customer B [Member] | Credit Concentration Risk [Member] | Accounts Receivable, Net [Member]
Concentration Risk [Line Items]
Customer concentration, percentage	12.00%

Summary of Significant Accoun36

Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives of Assets (Detail)	12 Months Ended
	Dec. 31, 2015
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life	3 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Leasehold improvements, description of estimated useful life	Shorter of lease term or estimated life of the assets
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life	3 years
Computer Equipment and Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life	2 years
Computer Equipment and Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life	3 years
Manufacturing Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life	5 years

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis Based on Three-Tier Fair Value Hierarchy (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets
Assets	$ 44,750	$ 5,678
Liabilities
Liabilities		136
Convertible Preferred Stock Warrant Liability [Member]
Liabilities
Liabilities		136
Level 1 [Member] | Recurring [Member]
Assets
Assets	44,750	5,678
Level 3 [Member] | Recurring [Member]
Liabilities
Liabilities		136
Level 3 [Member] | Recurring [Member] | Convertible Preferred Stock Warrant Liability [Member]
Liabilities
Liabilities		136
Money Market Funds [Member]
Assets
Assets	44,750	5,678
Money Market Funds [Member] | Level 1 [Member] | Recurring [Member]
Assets
Assets	$ 44,750	$ 5,678

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Changes in Fair Value of Convertible Preferred Stock Warrant Liability (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Beginning balance	$ 136	$ 86
Issuance of convertible preferred stock warrants		572
Change in fair value recorded in interest and other income (expense), net	$ (136)	(522)
Ending balance		$ 136

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Raw materials	$ 1,000	$ 894
Work-in-process	798	768
Finished goods	3,384	2,609
Total inventory	$ 5,182	$ 4,271

Balance Sheet Components - Sc40

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Prepaid expenses	$ 907	$ 420
Tenant improvement allowance receivable		2,064
Other	16	2
Total prepaid expenses and other current assets	$ 923	$ 2,486

Balance Sheet Components - Sc41

Balance Sheet Components - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 11,436	$ 9,399
Less: accumulated depreciation and amortization	(2,241)	(858)
Total property and equipment, net	9,195	8,541
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	1,341	633
Laboratory and Manufacturing Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	1,544	816
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	1,445	1,409
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 7,106	$ 6,541

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property Plant And Equipment [Abstract]
Depreciation and amortization	$ 1,710	$ 344	$ 227

Balance Sheet Components - Sc43

Balance Sheet Components - Schedule of Accrued and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Payables And Accruals [Abstract]
Accrued payroll-related expenses	$ 3,052	$ 1,599
Accrued independent sales agent commissions	158	227
Accrued professional fees	373	89
Accrued costs for property and equipment		1,453
Accrued sales and marketing expenses	45	95
Deferred rent, current	261	290
Other	325	409
Total accrued and other current liabilities	$ 4,214	$ 4,162

Related Party Loan Agreement -

Related Party Loan Agreement - Additional Information (Detail) - USD ($)	Feb. 28, 2014	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2015
Related Party Transaction [Line Items]
Interest expense on the loan			$ 1,777,000	$ 1,052,000	$ 0
HealthCare Royalty Partners [Member]
Related Party Transaction [Line Items]
Payments of debt issuance costs	$ 200,000
HealthCare Royalty Partners [Member] | Common Stock [Member] | IPO [Member]
Related Party Transaction [Line Items]
Warrants issued to purchase of shares						86,891
HealthCare Royalty Partners [Member] | Series E Convertible Preferred Stock [Member]
Related Party Transaction [Line Items]
Warrants issued to purchase of shares	84,553
Exercise price of warrants	$ 13.3052
Warrants liability	$ 572,000
HealthCare Royalty Partners [Member] | Loans Payable [Member] | Loan Agreement [Member]
Related Party Transaction [Line Items]
Debt instrument, fixed interest rate			12.50%
Debt instrument, maturity date			Dec. 31, 2020
Interest expense on the loan			$ 1,800,000	$ 1,100,000
HealthCare Royalty Partners [Member] | Loans Payable [Member] | Loan Agreement [Member] | Tranche One [Member]
Related Party Transaction [Line Items]
Debt instrument, drawn amount	$ 10,000,000
HealthCare Royalty Partners [Member] | Loans Payable [Member] | Loan Agreement [Member] | Tranche Two [Member]
Related Party Transaction [Line Items]
Debt instrument, drawn amount		$ 5,000,000

Related Party Loan Agreement 45

Related Party Loan Agreement - Schedule of Future Payments under Company's Loan Agreements (Detail) - HealthCare Royalty Partners [Member] $ in Thousands	Dec. 31, 2015USD ($)
Related Party Transaction [Line Items]
2,016	$ 1,874
2,017	3,305
2,018	4,547
2,019	5,601
Thereafter	6,469
Total	21,796
Less: Amount representing interest	(6,796)
Less: Amount representing debt discount	(520)
Future payments due, net	$ 14,480

Debt - Additional Information (

Debt - Additional Information (Detail) - Silicon Valley Bank [Member] - USD ($)	Feb. 28, 2014	Feb. 28, 2015	Feb. 28, 2014	Jul. 31, 2013	Dec. 31, 2015
Tranche III [Member]
Debt Instrument [Line Items]
Debt instrument, repayment of loan payable			$ 2,700,000	$ 1,900,000
New term loan				$ 2,500,000
Debt instrument, fixed interest rate				6.00%
Loan payment terms					Thereafter, the Company was obligated to pay monthly cash payments of principal and interest for a 30-month period with a balloon payment at maturity which was accreted as interest expense over the term of the loan.
Frequency periodic payment of loan					monthly
Loan term period				30 months
Percentage of prepayment penalty				2.00%
Loan maturity date					February 2,014
Tranche III [Member] | Series D Convertible Preferred Stock [Member]
Debt Instrument [Line Items]
Debt conversion number of warrants issued				11,294
Debt conversion warrant price per share				$ 12.395
Warrants liability				$ 23,000
Loan interest rate, effective percentage				13.30%
Unamortized balance of debt discount	$ 19,000		19,000
Prepayment penalty on debt	50,000
Unamortized portion of balloon interest payment	$ 143,000		$ 143,000
Accounts Receivable Credit Facility [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity		$ 7,500,000
Credit facility, percentage of maximum borrowings on eligible accounts receivable		80.00%
Line of credit facility maturity month and year					2018-02
Credit facility, interest rate description					Interest on borrowed amounts is payable monthly at the prime rate plus 0.75%.
Credit facility, covenant terms					The credit facility states that if the Company maintains a net cash balance, defined as unrestricted cash held with SVB less any borrowings on the revolving line of credit, of more than $3.0 million, then all collections will be deposited in the Company’s operating account. If the net cash balance is below $3.0 million, then all collections will be held in an SVB-controlled account and applied to reduce the loan balance.
Credit facility, net cash balance		$ 3,000,000
Credit facility, frequency of interest payment					Monthly
Accounts Receivable Credit Facility [Member] | Revolving Credit Facility [Member] | Prime Rate [Member]
Debt Instrument [Line Items]
Credit facility, monthly interest rate					0.75%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Nov. 01, 2014
Other Commitments [Line Items]
Rent expense	$ 2	$ 0.6	$ 0.3
Non-Cancelable Facility Lease Agreement [Member]
Other Commitments [Line Items]
Commencement date of lease	Nov. 1, 2014
Lease expiration date	Oct. 31, 2024
Security deposit				$ 1.1
Tenant allowance		2.6
Tenant allowance utilized		$ 2.6

Commitments and Contingencies48

Commitments and Contingencies - Summary of Company's Future Minimum Lease Payments (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,016	$ 2,053
2,017	2,114
2,018	2,178
2,019	2,243
2,020	2,310
Thereafter	9,511
Total	$ 20,409

Warrants - Additional Informati

Warrants - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2010
Class Of Warrant Or Right [Line Items]
Changes in fair value of convertible preferred stock warrant liability	$ 472,000	$ (522,000)	$ (168,000)
Convertible Preferred Stock Warrants [Member]
Class Of Warrant Or Right [Line Items]
Changes in fair value of convertible preferred stock warrant liability	$ 472,000	$ (522,000)	$ (168,000)
Common Stock Warrants [Member]
Class Of Warrant Or Right [Line Items]
Warrants issued to purchase of shares				3,532
Exercise price of warrants				$ 1.30
Preferred Stock Warrants [Member] | Financings between 2008 and 2014 [Member]
Class Of Warrant Or Right [Line Items]
Warrants issued to purchase of shares	130,540
Convertible Preferred Stock Warrants [Member] | Financings between 2008 and 2014 [Member] | IPO [Member]
Class Of Warrant Or Right [Line Items]
Warrants issued to purchase of shares	137,007
Black Scholes Based Option Pricing Model [Member] | Common Stock Warrants [Member]
Class Of Warrant Or Right [Line Items]
Warrants liability				$ 3,000

Convertible Preferred Stock a50

Convertible Preferred Stock and Stockholders' Deficit - Additional Information (Detail) - shares	2 Months Ended
	Mar. 31, 2015	Dec. 31, 2015	Jun. 30, 2015	Jun. 14, 2015	Dec. 31, 2014
Temporary Equity [Line Items]
Convertible preferred stock, shares outstanding		0		7,652,615	6,056,403
Series F Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Convertible preferred stock, shares issued during period	1,596,212
Common Stock [Member]
Temporary Equity [Line Items]
Convertible preferred stock converted into shares of common stock			7,979,332
Common Stock [Member] | Anti-dilution Adjustments [Member]
Temporary Equity [Line Items]
Convertible preferred stock converted into shares of common stock			326,717

Stock Option Plans - Additional

Stock Option Plans - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2015	Apr. 30, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance	3,445,228
Number of shares available for future awards	1,406,439		315,876
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance		1,494,272
Increase in number of shares available for issuance, description	The number of shares available for issuance under the 2015 Plan will be increased on the first day of each fiscal year in an amount equal to the lessor of (i) 1,494,272 shares; (ii) five percent of the outstanding shares on the last day of the immediately preceding fiscal year or (iii) such number of shares determined by the Company’s board of directors.
Stock option vesting, description	Employee stock options under the 2015 plan generally vest 20% upon one year of continued service to the Company, with the remainder in monthly increments over four additional years. Options expire no more than ten years after the date of grant.
2015 Plan [Member] | Incentive Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option granted to employees or director upon minimum percentage of voting right	10.00%
2015 Plan [Member] | Employee [Member] | Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting, percentage	20.00%
Stock option vesting, term	1 year
2015 Plan [Member] | Employee [Member] | Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting, term	4 years
2015 Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares available for issuance	1,494,272
Increase in number of shares available for issuance, percentage	5.00%
2015 Plan [Member] | Minimum [Member] | Employees or Directors Holding Less Than 10% of Voting Power [Member] | Incentive Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of fair value of common stock on grant date	110.00%
2015 Plan [Member] | Minimum [Member] | Employees or Directors Holding More Than 10% of Voting Power [Member] | Incentive Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of fair value of common stock on grant date	100.00%
2015 Plan [Member] | Minimum [Member] | Employees, Directors and Consultants [Member] | Nonstatutory Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of fair value of common stock on grant date	100.00%
2015 Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option expiration period	10 years
2005 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future awards		169,529
Stock option vesting, description	Employee stock options granted under the 2005 plan generally vest 25% upon one year of continued service to the Company, with the remainder in monthly increments over three additional years. Stock options granted to consultants generally vest over the performance period of the consultancy agreement, ranging from two to four years. Options expire no more than ten years after the date of grant.
2005 Plan [Member] | Incentive Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of stock option granted on fair value of common stock at grant date	100.00%
2005 Plan [Member] | Nonstatutory Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of stock option granted on fair value of common stock at grant date	85.00%
2005 Plan [Member] | Employee [Member] | Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting, percentage	25.00%
Stock option vesting, term	1 year
2005 Plan [Member] | Employee [Member] | Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting, term	3 years
2005 Plan [Member] | Minimum [Member] | Consultants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting, term	2 years
2005 Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option expiration period	10 years
2005 Plan [Member] | Maximum [Member] | Consultants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting, term	4 years

Stock Option Plans - Summary of

Stock Option Plans - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Apr. 30, 2014
Compensation Related Costs [Abstract]
Options Available for Grant, Beginning Balances	315,876
Options Available for Grant, Options authorized	1,852,097
Options Available for Grant, Options granted	(865,976)
Options Available for Grant, Options forfeited	104,442
Options Available for Grant, Ending Balances	1,406,439
Options Outstanding, Beginning Balances	1,379,503
Options Outstanding, Options granted	865,976
Options Outstanding, Options exercised	(102,250)
Options Outstanding, Options forfeited	(104,442)
Options Outstanding, Ending Balances	2,038,787
Options Outstanding, Options exercisable	975,314
Options Outstanding, Options vested and expected to vest	1,929,208	348,871
Weighted Average Exercise Price Per Share, Beginning Balances	$ 2.57
Weighted Average Exercise Price Per Share, granted	12.57
Weighted Average Exercise Price Per Share, exercised	1.39
Weighted Average Exercise Price Per Share, forfeited	6.17
Weighted Average Exercise Price Per Share, Ending Balances	6.69
Weighted Average Exercise Price Per Share, Options exercisable	3.28
Weighted Average Exercise Price Per Share, Options vested and expected to vest	$ 6.42
Aggregate Intrinsic Value, Beginning Balances	$ 7,504
Aggregate Intrinsic Value, Options exercisable	5,660
Aggregate Intrinsic Value, Options vested and expected to vest	$ 7,409

Stock Option Plans - Addition53

Stock Option Plans - Additional Information 1 (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Compensation Related Costs [Abstract]
Aggregate intrinsic value of options exercised	$ 796,000	$ 310,000	$ 24,000
Weighted average grant date fair value of options, granted	$ 4.82	$ 5.99	$ 4.32
Weighted-average remaining contractual life of options outstanding	7 years 9 months 18 days	7 years 9 months 18 days
Weighted-average remaining contractual life of options outstanding, vested and expected to vest	7 years 8 months 12 days	7 years 8 months 12 days
Stock option repurchase, term	4 years
Common stock outstanding, right to repurchase	8,648	17,566
Weighted average price of stock repurchase	$ 2.49	$ 2.34
Right to repurchase of shares, term	The Company’s right to repurchase these shares generally lapses 1/48 of the original grant date amount per month over four years.

Stock Option Plans - Schedule o

Stock Option Plans - Schedule of Options Outstanding, Vested and Currently Exercisable by Exercise Price (Detail) - 2015 Plan [Member]	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding, Number of Options | shares	2,038,789
Options Outstanding, Weighted-Average Remaining Contractual Life (year)	7 years 9 months 18 days
Options Outstanding, Weighted Average Exercise Price Per Share	$ 6.69
Options Exercisable, Number of Options | shares	975,314
Options Exercisable, Weighted Average Exercise Price Per Share	$ 3.28
1.30 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range	$ 1.30
Options Outstanding, Number of Options | shares	300,733
Options Outstanding, Weighted-Average Remaining Contractual Life (year)	4 years 8 months 12 days
Options Outstanding, Weighted Average Exercise Price Per Share	$ 1.30
Options Exercisable, Number of Options | shares	300,733
Options Exercisable, Weighted Average Exercise Price Per Share	$ 1.30
$1.48-2.78 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	1.48
Exercise Price Range, Upper Range Limit	$ 2.78
Options Outstanding, Number of Options | shares	71,748
Options Outstanding, Weighted-Average Remaining Contractual Life (year)	6 years
Options Outstanding, Weighted Average Exercise Price Per Share	$ 2.01
Options Exercisable, Number of Options | shares	68,343
Options Exercisable, Weighted Average Exercise Price Per Share	$ 1.98
$3.15 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range	$ 3.15
Options Outstanding, Number of Options | shares	831,426
Options Outstanding, Weighted-Average Remaining Contractual Life (year)	7 years 6 months
Options Outstanding, Weighted Average Exercise Price Per Share	$ 3.15
Options Exercisable, Number of Options | shares	510,397
Options Exercisable, Weighted Average Exercise Price Per Share	$ 3.15
$4.81-11.09 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	4.81
Exercise Price Range, Upper Range Limit	$ 11.09
Options Outstanding, Number of Options | shares	107,818
Options Outstanding, Weighted-Average Remaining Contractual Life (year)	9 years 6 months
Options Outstanding, Weighted Average Exercise Price Per Share	$ 10.23
Options Exercisable, Number of Options | shares	19,504
Options Exercisable, Weighted Average Exercise Price Per Share	$ 8.39
$11.10 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range	$ 11.10
Options Outstanding, Number of Options | shares	336,160
Options Outstanding, Weighted-Average Remaining Contractual Life (year)	9 years 1 month 6 days
Options Outstanding, Weighted Average Exercise Price Per Share	$ 11.10
Options Exercisable, Number of Options | shares	63,991
Options Exercisable, Weighted Average Exercise Price Per Share	$ 11.10
$11.96-14.25 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	11.96
Exercise Price Range, Upper Range Limit	$ 14.25
Options Outstanding, Number of Options | shares	241,218
Options Outstanding, Weighted-Average Remaining Contractual Life (year)	9 years 9 months 18 days
Options Outstanding, Weighted Average Exercise Price Per Share	$ 13.54
Options Exercisable, Number of Options | shares	770
Options Exercisable, Weighted Average Exercise Price Per Share	$ 12.49
$15.91 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range	$ 15.91
Options Outstanding, Number of Options | shares	149,686
Options Outstanding, Weighted-Average Remaining Contractual Life (year)	9 years 4 months 24 days
Options Outstanding, Weighted Average Exercise Price Per Share	$ 15.91
Options Exercisable, Number of Options | shares	11,576
Options Exercisable, Weighted Average Exercise Price Per Share	$ 15.91

Stock Option Plans - Addition55

Stock Option Plans - Additional Information 2 (Detail) - USD ($)	Apr. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense recognized		$ 1,100,000	$ 600,000	$ 300,000
Unamortized compensation expense related to unvested options		$ 4,100,000	$ 2,000,000
Weighted-average expected period to recognize of compensation expense, term		3 years 7 months 6 days	3 years
Options Outstanding, Options vested and expected to vest	348,871	1,929,208
Vested and unvested stock option award exercise price		$ 6.42
Modification, incremental cost	$ 226,000
Expense recognized based on options vested at the time of modification of terms	158,000
Incremental value attributed to unvested shares being recognized over the remaining vesting term	$ 68,000
Unvested shares		49,000
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested and unvested stock option award exercise price	$ 4.81
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested and unvested stock option award exercise price	$ 3.15

Stock Option Plans - Schedule56

Stock Option Plans - Schedule of Assumptions Used in Estimated Fair Value of Share-based Compensation for Options Granted (Detail) - Employee [Member]	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)		6 years	6 years
Expected volatility			43.00%
Dividend yield	0.00%	0.00%	0.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years
Expected volatility	35.00%	35.00%
Risk-free interest rate	1.31%	1.80%	1.08%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years
Expected volatility	50.00%	38.00%
Risk-free interest rate	1.89%	1.93%	1.82%

Stock Option Plans - Addition57

Stock Option Plans - Additional Information 3 (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1,249,000	$ 663,000	$ 279,000
Non-employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 103,000	$ 57,000	$ 13,000

Stock Option Plans - Summary 58

Stock Option Plans - Summary of Total Stock-based Compensation Expense Included in Statements of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 1,249	$ 663	$ 279
Cost of Goods Sold [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	89	23	4
Selling, General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	860	547	233
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 300	$ 93	$ 42

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Line Items]
Income before income taxes, U.S.	$ (37,600,000)	$ (20,700,000)	$ (12,100,000)
Income before income taxes, Foreign	0	0	0
Provision for income taxes	0	0	0
Increase decrease in deferred tax asset valuation allowance	12,700,000	7,500,000	$ 4,900,000
Unrecognized tax benefits, interest and penalties accrued	$ 0	$ 0
Earliest Tax Year
Income Tax Disclosure [Line Items]
Tax year open for income tax examination	2,005
Latest Tax Year
Income Tax Disclosure [Line Items]
Tax year open for income tax examination	2,014
Federal [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards before tax effects	$ 95,200,000
Net operating loss carryforwards expiration year	2,026
Research and development tax credits carryforwards	$ 700,000
Research and development tax credits expiration year	2,024
Tax years under examination	3 years
State [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards before tax effects	$ 60,900,000
Net operating loss carryforwards expiration year	2,017
Research and development tax credits carryforwards	$ 900,000
Research and development tax credits expiration term	indefinitely
Tax years under examination	4 years

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of the Statutory Federal Income Tax Rate to the Company's Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Tax at statutory federal rate	34.00%	34.00%	34.00%
State taxes, net of federal benefit	0.40%	3.80%	4.90%
Tax credits	0.90%	1.30%	1.00%
Change in valuation allowance	(33.90%)	(37.80%)	(40.10%)
Other	(1.40%)	(1.30%)	0.20%
Provision for income taxes	0.00%	0.00%	0.00%

Income Taxes - Summary of Signi

Income Taxes - Summary of Significant Portions of the Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Net operating loss carryforwards	$ 35,474	$ 23,574	$ 17,364
Research and development	986	782	626
Accrued liabilities and other	935	590	509
Stock-based compensation	485	259	194
Fixed assets	219	100	95
Tenant improvement allowance	836	970
Total deferred tax assets	38,935	26,275	18,788
Valuation allowance	(38,935)	(26,275)	(18,788)
Net deferred tax assets	$ 0	$ 0	$ 0

Income Taxes - Schedule of Re62

Income Taxes - Schedule of Reconciliation of the Company's Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 261	$ 209	$ 157
Additions for tax positions taken in current year	86	69	52
Reductions for tax positions taken in prior years	(18)	(17)
Balance at end of year	$ 329	$ 261	$ 209

Net Loss per Common Share - Sch

Net Loss per Common Share - Schedule of Computation of Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net loss	$ (10,055)	$ (9,138)	$ (9,346)	$ (9,031)	$ (5,203)	$ (5,290)	$ (5,456)	$ (4,713)	$ (37,570)	$ (20,662)	$ (12,109)
Denominator:
Weighted-average common shares outstanding									7,619,696	673,573	633,146
Less: weighted-average unvested common shares subject to repurchase									(13,524)	(20,378)	(739)
Weighted-average shares used to compute net loss per common share, basic and diluted	13,307,031	13,292,849	2,919,823	703,637	669,202	651,959	649,511	641,810	7,606,172	653,195	632,407
Net loss per common share, basic and diluted	$ (0.76)	$ (0.69)	$ (3.20)	$ (12.84)	$ (7.78)	$ (8.11)	$ (8.40)	$ (7.34)	$ (4.94)	$ (31.63)	$ (19.15)

Net Loss per Common Share - S64

Net Loss per Common Share - Schedule of Potentially Dilutive Securities Outstanding Excluded from Computation of Diluted Shares Outstanding (Detail) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	2,175,796	7,763,801	5,613,334
Convertible Preferred Stock on an as-Converted Basis [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share		6,246,196	4,648,382
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	2,038,789	1,379,503	911,403
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	137,007	3,532	3,532
Warrants to Purchase Convertible Preferred Stock on an as-Converted Basis [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share		134,570	50,017

Selected Quarterly Informatio65

Selected Quarterly Information (Unaudited) - Schedule of Selected Quarterly Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 6,246	$ 5,595	$ 4,748	$ 4,442	$ 4,409	$ 3,724	$ 2,817	$ 2,153	$ 21,031	$ 13,103	$ 7,186
Gross profit	4,119	3,561	2,898	2,720	3,010	2,430	1,588	1,445	13,298	8,473	4,892
Loss from operations	(9,567)	(8,661)	(8,866)	(8,113)	(5,348)	(4,920)	(5,112)	(4,371)	(35,207)	(19,752)	(11,955)
Net loss	$ (10,055)	$ (9,138)	$ (9,346)	$ (9,031)	$ (5,203)	$ (5,290)	$ (5,456)	$ (4,713)	$ (37,570)	$ (20,662)	$ (12,109)
Net loss per common share, basic and diluted	$ (0.76)	$ (0.69)	$ (3.20)	$ (12.84)	$ (7.78)	$ (8.11)	$ (8.40)	$ (7.34)	$ (4.94)	$ (31.63)	$ (19.15)
Weighted-average shares used to compute net loss per common share, basic and diluted	13,307,031	13,292,849	2,919,823	703,637	669,202	651,959	649,511	641,810	7,606,172	653,195	632,407