REVA Medical (RVALL) 10-K 7 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 23, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	REVA Medical, Inc.
Entity Central Index Key	1,496,268
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Trading Symbol	RVA
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 180,077,000
Entity Common Stock, Shares Outstanding		41,245,820
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents	$ 18,544	$ 6,674
Investment securities	1,470
Accounts receivable	63
Inventory	627
Prepaid expenses and other current assets	438	472
Total current assets	21,142	7,146
Non-Current Assets:
Property and equipment, net	1,492	2,277
Other non-current assets	27	60
Total non-current assets	1,519	2,337
Total Assets	22,661	9,483
Current Liabilities:
Accounts payable	756	778
Accrued expenses and other current liabilities	1,737	2,173
Deferred revenue	158
Convertible notes		91,655
Accrued interest on convertible notes		4,204
Total current liabilities	2,651	98,810
Long-Term Liabilities:
Convertible notes	99,368
Accrued interest on convertible notes	8,779
Common stock warrant liability	4,176
Other long-term liabilities	500	266
Total long-term liabilities	112,823	266
Total Liabilities	115,474	99,076
Commitments and contingencies (Note 9)
Stockholders' Deficit:
Common stock ― $0.0001 par value; 100,000,000 shares authorized; 41,245,820 and 42,851,477 shares issued and outstanding at December 31, 2017 and December 31, 2016, respectively	4	4
Additional paid-in capital	289,342	299,643
Accumulated other comprehensive loss	(2)	(2)
Accumulated deficit	(382,157)	(389,238)
Total Stockholders' Deficit	(92,813)	(89,593)
Total Liabilities and Stockholders' Deficit	$ 22,661	$ 9,483

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	41,245,820	42,851,477
Common stock, shares outstanding	41,245,820	42,851,477

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenue	$ 45,000
Cost of revenue	42,000
Gross profit	3,000
Operating Expense:
Research and development	12,760,000	$ 18,171,000	$ 16,760,000
Selling, general and administrative	8,572,000	8,609,000	7,210,000
Loss from operations	(21,329,000)	(26,780,000)	(23,970,000)
Other Income (Expense):
Interest income	57,000	3,000	9,000
Interest expense	(6,690,000)	(2,053,000)	(1,904,000)
Loss on issuance of convertible notes and warrants to purchase common stock	(520,000)
Gain (loss) on change in fair value of convertible notes and warrant liability	35,731,000	(25,247,000)	(56,788,000)
Other (expense) income	(115,000)	(21,000)	59,000
Total other income (expense)	28,463,000	(27,318,000)	(58,624,000)
Net Income (Loss)	$ 7,134,000	$ (54,098,000)	$ (82,594,000)
Net income (loss) per share - basic	$ 0.17	$ (1.28)	$ (2.38)
Weighted average shares outstanding - basic	41,811,326	42,120,545	34,680,634
Net loss per share - diluted	$ (0.40)	$ (1.28)	$ (2.38)
Weighted average shares outstanding - diluted	53,317,482	42,120,545	34,680,634
Comprehensive Income (Loss):
Net income (loss)	$ 7,134,000	$ (54,098,000)	$ (82,594,000)
Other comprehensive income (loss)	0	0	(1,000)
Comprehensive income (loss)	$ 7,134,000	$ (54,098,000)	$ (82,595,000)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows from Operating Activities:
Net income (loss)	$ 7,134	$ (54,098)	$ (82,594)
Non-cash adjustments to reconcile net income (loss) to net cash used for operating activities:
Depreciation and amortization	1,062	1,139	1,096
Loss on sale of property and equipment	52
Stock-based compensation	2,047	4,723	3,434
Interest on convertible notes	6,690	2,053	1,904
Loss on issuance of convertible notes and warrants to purchase common stock	520
(Gain) loss on change in fair value of convertible notes and warrant liability	(35,731)	25,247	56,788
Other non-cash expenses		21	46
Changes in operating assets and liabilities:
Accounts receivable	(63)
Inventory	(570)
Prepaid expenses and other current assets	84	(75)	9
Other non-current assets	33
Accounts payable	(72)	(244)	365
Accrued expenses and other current liabilities	(436)	(90)	33
Deferred revenue	158
Other long-term liabilities	234	65	(163)
Net cash used for operating activities	(18,858)	(21,259)	(19,082)
Cash Flows from Investing Activities:
Purchases of property and equipment	(386)	(729)	(857)
Purchases of investments	(1,470)
Maturities of investments			995
Net cash (used for) provided by investing activities	(1,856)	(729)	138
Cash Flows from Financing Activities:
Proceeds from issuances of common stock	92	11,767	10,075
Repurchase of common stock	(12,493)
Proceeds from (costs of) issuance of convertible notes payable and warrants, net	44,985		(50)
Net cash provided by financing activities	32,584	11,767	10,025
Net increase (decrease) in cash and cash equivalents	11,870	(10,221)	(8,919)
Cash and cash equivalents at beginning of period	6,674	16,895	25,814
Cash and Cash Equivalents at End of Period	18,544	6,674	16,895
Supplemental Non-Cash Information:
Property and equipment in accounts payable	11	18	50
Adjustment to beginning accumulated deficit upon adoption of ASU 2016-09	$ 53
Warrant liability transferred to equity upon exercise		$ 28,579	$ 14,970

Consolidated Statement of Stock

Consolidated Statement of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid In Capital	Accumulated Other Comprehensive Income/(Loss)	Accumulated Deficit
Balance at Dec. 31, 2014	$ (26,449)	$ 3	$ 226,095	$ (1)	$ (252,546)
Balance (in shares) at Dec. 31, 2014		33,529,778
Increase (Decrease) in Stockholders' Equity
Net loss and comprehensive loss	(82,594)				(82,594)
Common stock issued upon exercise of stock options for cash	570	$ 0	570
Common stock issued upon exercise of stock options for cash (in shares)		251,208
Common stock issued upon exercise of warrants for cash	$ 9,506	$ 1	9,505
Common stock issued upon exercise of warrants for cash (in shares)		4,375,000
Common stock issued upon net exercise of stock options (in shares)	251,208
Fair value of warrant liability transferred to equity upon warrant exercise	$ 14,970		14,970
Stock-based compensation expense	3,434		3,434
Other comprehensive income (loss)	(1)			(1)
Balance at Dec. 31, 2015	(80,564)	$ 4	254,574	(2)	(335,140)
Balance (in shares) at Dec. 31, 2015		38,155,986
Increase (Decrease) in Stockholders' Equity
Net loss and comprehensive loss	(54,098)				(54,098)
Common stock issued upon exercise of stock options for cash	360	$ 0	360
Common stock issued upon exercise of stock options for cash (in shares)		132,916
Common stock issued upon exercise of warrants for cash	11,407	$ 0	11,407
Common stock issued upon exercise of warrants for cash (in shares)		4,375,000
Common stock issued upon vesting of restricted stock units	0	$ 0
Common stock issued upon vesting of restricted stock units (in shares)		160,000
Common stock issued upon net exercise of stock options	$ 0	$ 0
Common stock issued upon net exercise of stock options (in shares)	247,499	27,575
Fair value of warrant liability transferred to equity upon warrant exercise	$ 28,579		28,579
Stock-based compensation expense	4,723		4,723
Other comprehensive income (loss)	0			0
Balance at Dec. 31, 2016	$ (89,593)	$ 4	299,643	(2)	(389,238)
Balance (in shares) at Dec. 31, 2016	42,851,477	42,851,477
Increase (Decrease) in Stockholders' Equity
Net loss and comprehensive loss	$ 7,134				7,134
Reversal of forfeiture estimates			53		(53)
Common stock issued upon exercise of stock options for cash	92	$ 0	92
Common stock issued upon exercise of stock options for cash (in shares)		65,000
Common stock issued upon vesting of restricted stock units	0	$ 0
Common stock issued upon vesting of restricted stock units (in shares)		47,800
Common stock issued upon net exercise of stock options	$ 0	$ 0
Common stock issued upon net exercise of stock options (in shares)	121,678	13,803
Stock repurchase associated with convertible debt financing	$ (12,493)	$ 0	(12,493)
Stock repurchase associated with convertible debt financing (in shares)		(1,732,260)
Stock-based compensation expense	2,047		2,047
Other comprehensive income (loss)	0			0
Balance at Dec. 31, 2017	$ (92,813)	$ 4	$ 289,342	$ (2)	$ (382,157)
Balance (in shares) at Dec. 31, 2017	41,245,820	41,245,820

Consolidated Statement of Stoc7

Consolidated Statement of Stockholders' Equity (Deficit) (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock issued, price per share		2.6073	$ 2.17275
Minimum
Common stock, par value (in dollars per share)	1.40	1.40	1.25
Maximum
Common stock, par value (in dollars per share)	$ 1.50	$ 4	$ 5.60

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2017
Description Of Business [Abstract]
Description of Business	1. Description of Business REVA Medical, Inc. was incorporated in California in 1998 under the name MD3, Inc. In March 2002, we changed our name to REVA Medical, Inc. In October 2010 we reincorporated in Delaware. We established a non-operating wholly owned subsidiary, REVA Germany GmbH, in 2007. In these Notes to Consolidated Financial Statements, the terms “REVA,” the “Company,” “us,” “we,” or “our” refer to REVA and its consolidated subsidiary unless context dictates otherwise. We are a medical device company focused on developing and commercializing products for use in humans, utilizing our proprietary bioresorbable polymer technologies. On April 3, 2017, we received approval for the marketing and sale of our first product, the Fantom scaffold, in Europe and other jurisdictions that recognize the CE Mark. Our Fantom scaffold is a sirolimus-eluting bioresorbable scaffold used to treat coronary artery disease in humans. We received our first customer order late in the second quarter of 2017 and we recorded our first order shipments and revenues in the third quarter of 2017. Prior to CE Mark, Fantom had been implanted in 247 patients in the FANTOM I and FANTOM II clinical trials conducted in eight countries outside the United States. We used the six-month clinical results from 117 patients in the FANTOM II clinical trial for CE Mark application, which we submitted in 2016. In December 2010, we completed an initial public offering (the “IPO”) of our common stock in Australia and registered with the U.S. Securities and Exchange Commission (“SEC”) and, consequently, became an SEC reporting company. Our common stock is traded in the form of CHESS Depositary Interests (“CDIs”) on the Australian Securities Exchange (“ASX”); each share of our common stock is equivalent to ten CDIs. Our trading symbol is “RVA.AX.” We may pursue a listing of our common stock on a U.S. stock exchange, at which time we would become dual-listed, if we maintain our listing on the ASX.

Capital Resources and Basis of

Capital Resources and Basis of Presentation	12 Months Ended
	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Capital Resources and Basis of Presentation	2. Capital Resources and Basis of Presentation Capital Resources : The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. We have incurred significant operating losses since inception and have relied on our ability to fund our operations primarily through equity and debt financings. At December 31, 2017, we had an accumulated deficit of $382.2 million and our cash, cash equivalents and investment securities totaled $20.0 million. Based on our current operating plans and projections, we believe our cash, cash equivalents and investment securities of $20.0 million will be sufficient to fund our operations through the first quarter of 2019. Our projections are predicated on us achieving certain minimum levels of sales of our Fantom scaffold. If we are unable to achieve these levels of sales, we may be compelled to reduce operating and capital expenditures or sell certain assets. Although we initiated commercial sales of Fantom in the third quarter of 2017, we are still very early in the commercialization stage. The withdrawal of Absorb, a competitor’s product, in 2017, and the negative publicity related to Absorb’s safety have severely impacted the market for bioresorbable scaffolds, and companies with bioresorbable scaffolds that were made from the same polylactic acid polymer, or PLLA, as Absorb have reduced scale and abandoned their efforts to commercialize such scaffolds. Because Fantom is not made with the same polymer as Absorb, we continue to believe that we can commercialize Fantom despite the impact that the withdrawal of Absorb has had on the market and demonstrate the benefits of bioresorbable technology. That said, we must now rebuild the market for bioresorbable scaffolds, which can be more challenging than selling into an existing, healthy market. Our rebuilding activities include educating physicians regarding the unique features of Fantom and Fantom Encore, continuing to publish results from our pivotal clinical trial (FANTOM II) and conducting and initiating additional clinical studies to build the clinical evidence needed to support market adoption Until we generate revenue at a level to support our cost structure, we expect to continue to incur substantial operating losses and net cash outflows. We may never become profitable and even if we do attain profitability, we may not be able to sustain profitability or positive cash flows on a recurring basis. Unless we are able to significantly accelerate our sales, we do not anticipate generating positive cash flows in 2018 or 2019, and therefore, will need to raise further capital to support our operations and our ongoing costs, and to conduct a U.S. clinical trial, if we determine to do so. We have a plan to address our capital needs, which includes accelerating our revenue by pursuing sales expansion and executing business development and strategic opportunities. We are also evaluating public or private sales of our equity or debt securities. In addition, the convertible notes we issued in 2014 mature in November 2019 and each holder of the convertible notes we issued in 2017 has a redemption right that it may exercise in November 2019. The aggregate face value of all such convertible notes and accrued interest is $72.1 million and $8.8 million, respectively, as of December 31, 2017. Convertible Notes and Warrants to Purchase Common Stock . Basis of Presentation : We have prepared the accompanying consolidated financial statements in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). The consolidated financial statements include the accounts of REVA and our wholly owned subsidiary, REVA Germany GmbH. All intercompany transactions and balances, if any, have been eliminated in consolidation. Use of Estimates : The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from our estimates.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Significant Accounting Policies	3. Significant Accounting Policies Cash Equivalents : We consider all highly liquid investments with original maturities of three months or less at the date of purchase to be cash equivalents. Cash equivalents are carried at cost, which we believe approximates fair value due to the short-term maturities of these investments. Investment Securities : Investment securities are marketable equity or debt securities. All of our investment securities are “available-for-sale” securities and carried at fair value. Fair value for securities with short maturities and infrequent secondary market trades typically is determined by using a curve-based evaluation model that utilizes quoted prices for similar securities. The evaluation model takes into consideration the days to maturity, coupon rate and settlement date convention. Net unrealized gains or losses on these securities are included in accumulated other comprehensive loss, which is a separate component of stockholders’ deficit. Realized gains and realized losses are included in other income (expense) while amortization of premiums and accretion of discounts are included in interest income. Interest and dividends on available-for-sale securities are included in interest income. We periodically evaluate our investment securities for impairment. If we determine that a decline in fair value of any investment security is other than temporary, then the cost basis would be written down to fair value and the decline in value would be charged to other expense at that time. Our investment securities are under the custodianship of a major financial institution and consist of certificates of deposit that are insured by the Federal Deposit Insurance Corporation. We have classified all of our available-for-sale investment securities as current assets on our consolidated balance sheets because we consider them to be highly liquid and available for use, if needed, in current operations. As of December 31, 2017, none of our $1.5 million of investment securities had contractual maturity dates of more than one year. Inventory: We received CE Mark approval of our Fantom scaffold on April 3, 2017, at which time we began capitalizing raw material purchases and commercial scaffold production costs to inventory. Inventory is stated at the lower of cost or net realizable value based on the first-in, first-out cost method (“FIFO”). Our policy is to record an estimated allowance against inventory for unsalable, obsolete, or impaired inventory, with a corresponding increase to cost of revenue. We record the cost of products to be used in research and development or clinical trials as research and development expense when inventory is requisitioned for such use. Impairment of Long-Lived Assets : We review our long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable and exceeds its undiscounted future cash flows. The amount of impairment, if any, is determined by comparing an asset’s estimated fair value to the asset’s respective carrying amount. During the years ended December 31, 2017, 2016, and 2015 we determined there were no indications of long-lived asset impairment. Convertible Notes : Convertible notes are analyzed at issue date to determine balance sheet classification, issue discounts or premiums, and embedded or derivative features. Embedded or derivative features are evaluated in accordance with accounting guidance for derivative securities and, if the features give rise to separate accounting, we make an election to account for the notes at cost or at fair value. If fair value accounting is elected on the issue date, we record the difference between the issue price of the notes and their fair value as a gain or loss in our consolidated statement of operations. We remeasure the fair value at each reporting date and record a gain (upon a decrease in fair value) or loss (upon an increase in fair value), as a component of other income (expense) in our consolidated statement of operations. Inputs to the models include the market value of the underlying stock, a life equal to the contractual life of the notes, incremental borrowing rates that correspond to debt with similar credit worthiness, and estimated volatility based on the historical prices of our trading securities. For each periodic valuation, we also make assumptions as to our abilities to test and commercialize our product, to obtain future financings when and if needed, and to comply with the terms and conditions of any outstanding notes payable. Following an analysis of their embedded and derivative features, we elected to utilize fair value accounting for all issues of convertible notes as management believes the convertible notes will be converted into common stock, rather than repaid, and the fair value method of accounting provides a more appropriate value of these liabilities than would be provided under the cost method. Common Stock Warrants : The fair value of warrants issued for the purchase of common stock is recorded as a liability whenever warrants call for issuance of registered shares upon exercise, a condition that we may not be able to satisfy at the time of exercise, and which, if not so satisfied, will result in a net settlement of warrants. Until the time warrants are exercised or expire, the fair value is assessed at each reporting date. Any change in value is recorded as a gain or loss component of other income (expense) in our consolidated statement of operations. Inputs to the valuation models are of the same nature as those used to value our convertible notes. Revenue : We received our first order for Fantom in June 2017. We sell Fantom to hospitals; and title and risk of loss transfer upon delivery to these hospitals. We recognize revenue when all of the following four criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery has occurred; (3) the fee is fixed or determinable; and (4) collectability is reasonably assured. We also consider any return or exchange rights. We analyze product reorder rates to evaluate and determine whether return or exchange rights exist and are likely to be exercised. If the revenue recognition criteria are not met, we defer the recognition of revenue by recording deferred revenue until such time that all criteria are met. We recognized $45,000 of revenue during the year ended December 31, 2017. Total billings for shipped product for this period were $203,000; the amount by which total billings for shipped product exceeded recognized revenue was recorded as deferred revenue. Accounts receivable consist of trade receivables recorded upon shipment of product reduced by reserves when necessary for estimated bad debts. Accounts receivable are recorded at the invoiced amount and do not bear interest. Credit is extended based on an evaluation of the customer’s financial condition. The allowance for doubtful accounts is determined based on current customer information and other relevant factors, including specific identification of past due accounts. Once a receivable is deemed to be uncollectible, such balance is charged against the allowance. As of December 31, 2017, our allowance for doubtful accounts was $0. Research and Development : Research and development costs are expensed as incurred. These costs include salaries, employee benefits, laboratory supplies, consulting services, manufacturing products and services, preclinical and clinical costs, technology license fees, laboratory equipment depreciation, facility costs, and certain indirect costs. Income Taxes : We account for income taxes using the asset and liability method, under which the current income tax expense or benefit is the amount of income tax expected to be payable or refundable in the current year. Deferred tax assets and liabilities are recorded for the estimated future tax consequences of temporary differences between the financial statement carrying amounts of assets and liabilities and their respective tax bases, and for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the year in which the temporary differences are expected to be recovered or settled. We evaluate the realizability of our deferred tax assets and establish a valuation allowance when it is more likely than not that all or a portion of our deferred tax assets will not be realized. In making such a determination, we consider all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax planning strategies, and results of recent operations. If we determine that we would be able to realize our deferred tax assets in the future in excess of their net recorded amount, we would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. We account for the uncertainty in income tax components based on tax positions taken or expected to be taken in a tax return. To recognize a benefit, a tax position must be more likely than not to be sustained upon examination by taxing authorities. We do not recognize tax benefits that have a less than 50 percent likelihood of being sustained. Our policy is to recognize interest and tax penalties related to unrecognized tax benefits in income tax expense; no interest or tax penalties on uncertain tax benefits have been recorded through December 31, 2017. Stock-Based Compensation : Stock-based compensation expense is recorded in connection with stock options, restricted stock awards, and restricted stock unit awards (“RSUs”) to employees, directors, and consultants. We have granted stock options, restricted stock, and RSUs that vest based on the passage of time (time-based vesting awards) as well as stock options and RSUs that vest based on achievement of performance milestones (performance-based vesting awards). For time-based vesting stock options granted to employees and directors, we determine compensation expense based on estimated grant date fair values utilizing the Black-Scholes option valuation model. The Black-Scholes model requires the input of assumptions, including volatility, the expected term, and the fair value of the underlying common stock on the date of grant, among other inputs. For time-based vesting restricted stock awards and RSUs, the grant date fair value is equal to the closing market price of our common stock on the date of award. We use the straight-line method to allocate compensation expense to reporting periods over each recipient’s requisite service period, which is generally from one to four years. All stock-based compensation expense is recorded as either research and development or selling, general and administrative expense based on a recipient’s work classification. For performance-based vesting stock options and RSUs, we record compensation expense for only the performance milestones that are probable of being achieved, with such expense recorded on a straight-line basis over the expected vesting period. We reassess our performance-based estimates each reporting period and, if the estimated service period changes, we recognize all remaining compensation expense over the remaining service period and, if the probability of achievement changes to or from “probable,” we recognize the cumulative effect. Whenever an award recipient terminates service prior to achievement of a performance milestone, the recipient’s unvested awards are cancelled and the related compensation expense previously recorded is reversed. For stock options granted to consultants, all of which are time-based vesting, we estimate fair values at the date of grant and at each subsequent reporting period and record compensation expense during the consultant’s service period. We estimate the fair value utilizing the Black-Scholes option valuation model with the same approach to inputs and assumptions as we use to estimate the fair value of employee options, except we use the remaining term as the expected life of the option. Foreign Currency : The functional currency of our subsidiary REVA Germany GmbH is the Euro. Balance sheet accounts of our subsidiary are translated into United States dollars using the exchange rate in effect at the balance sheet date while expenses are translated using the average exchange rate in effect during the period. Gains and losses arising from translation of our subsidiary’s financial statements are recorded to other comprehensive income (loss). These gains and losses, in the aggregate, were insignificant through December 31, 2017. Concentrations: Financial instruments that potentially subject us to concentrations of credit risk are primarily cash, cash equivalents and investment securities. Investment securities are invested in accordance with our investment policy. Our audit committee approved an investment policy that sets our investment parameters and limitations with objectives of preserving principal and liquidity. Periodically, we maintain deposits at financial institutions in excess of government insured limits. We invest our cash balances in major financial institutions that we believe have high credit quality and have not experienced any losses on such accounts. We do not believe we are exposed to significant credit risk. We require customized components that currently are available from a limited number of sources. We source certain components included in our products from single vendors. As we recently commenced commercial operations, our revenue in 2017 is more concentrated than we expect it to be after we expand commercially. Our top customer represented 26% of our total shipments in 2017. All of our shipments as of December 31, 2017 were made to customers outside of the United States as we only have approval to sell in countries that recognize CE Mark. We maintain inventory at our third-party logistics provider in The Netherlands. As of December 31, 2017, $127,000 of our inventory was held at this location. Segment Information: We operate in one business segment, which is the development and commercialization of medical devices. Recently Adopted Accounting Pronouncements : We adopted ASU 2016-09, Stock Compensation: Improvements to Employee Share-Based Payment Accounting , effective January 1, 2017. ASU 2016-09 simplifies certain aspects of accounting for stock-based compensation, including the accounting for income taxes, the option to recognize forfeiture credits as they occur rather than as an estimate of future activity, and classifications in the statement of cash flows. Upon the adoption, we recorded a cumulative effect adjustment to increase our accumulated deficit by approximately $53,000, with a corresponding increase to additional paid-in capital, to reverse our forfeiture estimate for unvested awards. All forfeitures occurring after adoption are being recognized in the consolidated statement of operations in the reporting period in which they occur. We had $1.8 million of forfeitures during the year ended December 31, 2017 related to a reduction in force that occurred in July 2017. See Note 11 Stock-Based Compensation . Recently Issued Accounting Pronouncements: In May 2014, the Financial Accounting Standards Board, or FASB, issued ASU 2014-09, Revenue from Contracts with Customers, which introduced Accounting Standards Codification 606 , Revenue from Contracts with Customers (“ASC 606”) , an updated standard on revenue recognition. The standard outlines a single comprehensive model to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. Revenue recognized under ASC 606 will represent the consideration an entity expects to be entitled to in exchange for the transfer of goods or services to a customer; it also requires additional disclosures about the nature, amount, timing, and uncertainty of revenue and cash flows arising from customer contracts. The standard permits two methods of adoption: retrospectively to each prior reporting period (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (modified retrospective method). We adopted ASC 606 effective January 1, 2018 and will utilize the modified retrospective method for adoption. The adoption of the standard will not result in a material transition adjustment. Total billings for shipped product for the year ended December 31, 2017 were $203,000. We are in the process of finalizing the new required disclosures. In January 2016, the FASB issued ASU No. 2016-01, “Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities” In February 2016, ASU 2016-02, Leases (Topic 842) In July 2017, ASU 2017-11, Earnings Per Share, Distinguishing Liabilities from Equity, Derivatives and Hedging

Inventory

Inventory	12 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
Inventory	4. Inventory The Company began capitalizing inventory upon CE Mark approval in the second quarter of 2017. Inventory consisted of the following at December 31, 2017 (in thousands): December 31, 2017 Raw materials $ 255 Work in process 61 Finished goods 329 Excess and obsolete reserve (18 ) $ 627

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Property and Equipment	5. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Property and equipment are depreciated using the straight-line method over the estimated useful lives of the assets, which is generally three to five years. Leasehold improvements are amortized over the economic life of the asset or the lease term, whichever is shorter. Upon disposition or retirement of an asset, its cost and related accumulated depreciation are written off and any gain or loss is recognized in the consolidated statement of operations Property and equipment at December 31, 2017 and 2016 are as follows (in thousands): December 31, 2017 2016 Furniture, office equipment, and software $ 601 $ 655 Laboratory equipment 5,705 6,604 Leasehold improvements 2,422 2,412 8,728 9,671 Accumulated depreciation and amortization (7,236 ) (7,394 ) $ 1,492 $ 2,277

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2017
Accounts Payable And Accrued Liabilities Current [Abstract]
Accrued Expenses and Other Current Liabilities	6. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities at December 31, 2017 and 2016 are as follows (in thousands): December 31, 2017 2016 Accrued salaries and other employee costs $ 1,296 $ 1,456 Accrued operating expenses 404 519 Accrued use taxes and other 37 198 $ 1,737 $ 2,173

Convertible Notes and Warrants

Convertible Notes and Warrants to Purchase Common Stock	12 Months Ended
	Dec. 31, 2017
Convertible Longterm Notes Payable Current And Noncurrent [Abstract]
Convertible Notes and Warrants to Purchase Common Stock	7. Convertible Notes and Warrants to Purchase Common Stock In May 2017, we issued 338 convertible notes and in June 2017 we issued 133 convertible notes (collectively, the “2017 Notes”), each with a face value of $100,000, for total gross cash proceeds of $47.1 million. We used a portion of the proceeds from this financing to repurchase 1,732,260 shares of our common stock from one of the investors in the 2017 Notes at $7.212 per share, for a total repurchase price of $12.5 million, and incurred transaction costs of $2.1 million, resulting in net proceeds from this financing of $32.5 million. The 2017 Notes are convertible at any time at the holders’ election; the conversion rate as of December 31, 2017 was $8.655 per share, which, if converted at that conversion rate, would result in issuing 5,441,941 shares of common stock upon conversion. The conversion rate may decrease depending on the price at which we issue securities in future financings, if any, to a minimum of $7.212 per share. The 2017 Notes mature five years from issue date, if not converted or redeemed earlier. Interest accrues at the rate of 8.0 percent per annum, compounded annually, and is payable upon redemption or maturity; accrued interest is not payable or convertible upon conversion of the notes. Each holder of the 2017 Notes has a right to request that we redeem the notes (face value plus accrued interest) on November 4, 2019, if they have not been previously converted or redeemed, if the holders have provided at least 30 days’ written notice to elect such a redemption. On their issue dates, we evaluated the 2017 Notes and, following an analysis of the embedded and derivative features, made an irrevocable election to account for the notes at fair value. The fair value on December 31, 2017 was estimated to be $38.4 million, $8.7 million below the $47.1 million face value of the 2017 Notes. In November 2014, we issued 250 convertible notes (the “2014 Notes”), each with a face value of $100,000, for total gross cash proceeds of $25.0 million. The 2014 Notes are convertible at any time at the holders’ election into a total of 11,506,156 shares of common stock, which reflects a conversion rate of $2.17275 per share. The 2014 Notes mature on November 14, 2019, if not converted or redeemed earlier. Interest accrues at the rate of 7.54 percent per annum, compounded annually, and is payable upon redemption or maturity; accrued interest is not payable or convertible upon conversion of the 2014 Notes. Effective June 1, 2017, the terms of the 2014 Notes that provided the holders with a one-time option to require us to redeem the notes on June 30, 2017 and that provided for an automatic conversion of the 2014 Notes were eliminated, and the 2014 Notes were modified to be subordinate to the 2017 Notes. Our stockholders approved the foregoing modifications to the terms of the 2014 Notes. On their issue date, we evaluated the 2014 Notes and, following an analysis of the embedded and derivative features, we made an irrevocable election to account for the notes at fair value. Following the modifications to the notes that were effective on June 1, 2017, we continued to account for the 2014 Notes under the fair value method. The fair values of the 2014 Notes as of December 31, 2017 and 2016 were calculated to be $61.0 million and $91.7 million, respectively. The fair value as of December 31, 2017 was $36.0 million higher than the $25.0 million face value of the 2014 Notes. Changes in the fair value of the 2014 Notes and 2017 Notes, which collectively we refer to as convertible notes, are recorded as gains or losses in the other income (expense) portion of our consolidated statement of operations. During the years ended December 31, 2017, 2016 and 2015, we accrued $4.6 million, $2.1 million and $1.9 million in interest expense on the convertible notes, respectively. Accrued interest on the 2014 Notes and 2017 Notes as of December 31, 2017 and 2016, in the aggregate, was $8.8 million and $4.2 million, respectively. An additional $2.1 million of transaction costs related to the issuance of the 2017 Notes was recorded as interest expense during the year ended December 31, 2017. In connection with issuing the 2017 Notes, in May 2017 and June 2017 we issued warrants to purchase up to 2,119,500 shares of our common stock to the purchasers of the 2017 Notes. The warrants are immediately exercisable and expire five years from issue date. The exercise price of each warrant is $5.00 per share, which may increase depending on the price at which we issue securities in future financings, if any, to a maximum of $7.212 per share. The fair value of the warrants on December 31, 2017 was estimated to be $4.2 million. Changes in the fair value of the warrants are recorded as gains or losses in the other income (expense) portion of our consolidated statement of operations. The aggregate fair value of the 2017 Notes and the warrants on their issue dates was estimated to be $47.6 million, which was $0.5 million higher than the $47.1 million issue price; we recorded this difference as a loss on issuance in our consolidated statement of operations. The warrants we issued in November 2014 in connection with issuance of the 2014 Notes were exercised in full on or before February 12, 2016. Prior to their exercise, we recorded their change in fair value in our consolidated statement of operations. The loss on the change in fair value from January 1, 2016 to February 12, 2016 was $9.0 million. As previously discussed, the 2014 Notes mature in November 2019 and each holder of the 2017 Notes has a redemption right that it may exercise in November 2019. The aggregate face value of all such convertible notes is $72.1 million and the aggregate accrued interest on all such notes was $8.8 million as of December 31, 2017. If the holders of the 2017 Notes collectively, or individually, call for redemption, or if we are unable to convert or extend the maturity date of the 2014 Notes, we most likely will not have the cash to repay the notes.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	REVA Medical, Inc. Notes to Consolidated Financial Statements 8. Fair Value Measurements Our cash equivalents, investment securities, convertible notes and common stock warrant liability are carried at fair value. The fair value of financial assets and liabilities is measured under a framework that establishes “levels” which are defined as follows: (i) Level 1 fair value is determined from observable, quoted prices for identical assets or liabilities; (ii) Level 2 fair value is determined from quoted prices for similar items in active markets or quoted prices for identical or similar items in markets that are not active, and (iii) Level 3 fair value is determined using the entity’s own assumptions about the inputs that market participants would use in pricing an asset or liability. The fair values of our cash equivalents, investment securities, convertible notes and common stock warrant liability are summarized in the following tables (in thousands): December 31, 2017 Total Fair Value Determined Under: Fair Value Level 1 Level 2 Level 3 Assets: Cash equivalents $ 4,388 $ 4,388 $ — $ — Investment securities $ 1,470 $ — $ 1,470 $ — Liabilities: Convertible notes payable $ 99,368 $ — $ — $ 99,368 Common stock warrant liability $ 4,176 $ — $ — $ 4,176 December 31, 2016 Total Fair Value Determined Under: Fair Value Level 1 Level 2 Level 3 Assets: Cash equivalents $ 6,655 $ 6,655 $ — $ — Liabilities: Convertible notes payable $ 91,655 $ — $ — $ 91,655 The fair values of our 2017 Notes as of December 31, 2017 and the fair values of our 2014 Notes as of December 31, 2016 were determined utilizing a Least Squares Monte Carlo simulation model; the fair value of our warrants to purchase common stock was determined using either a Least Squares Monte Carlo simulation model or a Black-Scholes valuation model, depending on their exercise price and other features. These models require use of unobservable inputs that are determined by management, with the assistance of independent experts. These inputs represent our best estimates, but involve certain inherent uncertainties. We use the market value of the underlying stock, a life equal to the contractual life of the financial instrument, incremental borrowing rates and bond yields that correspond to instruments of similar credit worthiness and the instrument’s remaining life, an estimate of volatility based on the historical prices of our trading securities, and we make assumptions as to our abilities to test and commercialize our product(s), to obtain future financings when and if needed, to comply with the terms and conditions of our convertible notes, and the probability of a change in control event. A summary of the weighted average assumptions used to value these Level 3 liabilities is as follows: Year Ended December 31, 2017 2016 Market price per share of common stock $ 5.31 $ 7.90 Risk-free interest rate 2.1% 2.0% Expected volatility of common stock 45.0% 79.7% Expected life (in years) 4.37 2.90 Bond yield of equivalent securities 26.5% 27.0% A significant change in the market price per share, expected volatility, or bond yield of equivalent securities, in isolation, would result in significantly higher or lower fair value measurements. In combination, changes in these inputs could result in a significantly higher or lower fair value measurement if the input changes were to be aligned, or could result in a minimally higher or lower fair value measurement if the input changes were of a compensating nature. As the 2014 Notes were significantly in the money and no longer had complex features as of December 31, 2017, we used an “as-converted” method for calculating the fair value of such notes. This involved multiplying the number of shares into which the 2014 Notes convert (11,506,156 shares) by the Company’s stock price as of December 29, 2017 (the last trading day of the year). We performed an evaluation as to whether the as-converted method would yield a materially different result from the Least Squares Monte Carlo simulation model used in previous quarters and determined that it would not. A reconciliation of the convertible notes and common stock warrant liability that are measured and recorded at fair value on a recurring basis using significant unobservable inputs (Level 3) is as follows: Convertible Common Stock Notes Payable Warrant Liability Balance at December 31, 2014 $ 37,780 $ 15,389 Total unrealized losses on change in fair value 37,585 19,203 Net settlements upon exercise of warrants — (14,970 ) Balance at December 31, 2015 $ 75,365 $ 19,622 Total unrealized losses on change in fair value 16,290 8,957 Net settlements upon exercise of warrants — (28,579 ) Balance at December 31, 2016 $ 91,655 $ — Net issuances 40,954 6,666 Total unrealized gains on change in fair value (33,241 ) (2,490 ) Balance at December 31, 2017 $ 99,368 $ 4,176 F-1

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies We license certain patents and other intellectual property rights related to the composition and coating of our bioresorbable scaffold and our other biomaterial products. Terms of these licenses include provisions for royalty payments on future sales of products, if any, utilizing this technology, with provisions for minimum royalties once product sales begin. The amount of royalties varies depending upon type of product, use of product, stage of product, location of sale, and ultimate sales volume, and ranges from a minimum of approximately $15 per unit sold to a maximum of approximately $50 per unit sold, with license provisions for escalating minimum royalties that could be as high as $2.2 million per year. Additionally, in the event we sublicense the technology and receive certain milestone payments, the licenses require that up to 40 percent of the milestone amount be paid to the licensors. Additional terms of the technology licenses include annual license fees of $175,000 until the underlying technology has been commercialized. Because we began commercial sales of our Fantom scaffold in July 2017, these annual license fees will not continue after 2017. Terms of the licenses also include other payments to occur during commercialization that could total $950,000, payment of $350,000 upon a change in control of ownership of the Company, payments of up to $300,000 annually to extend filing periods related to certain technology (of which, payments totaling up to $250,000 per year during the years 2016, 2017, and 2018 are being deferred to January 1, 2019; accordingly, $500,000 was accrued as a long-term liability at December 31, 2017), and payment of patent filing, maintenance, and defense fees. The license terms remain in effect until the last patent expires. In connection with our operating and business activities, we periodically enter into contracts with consultants and suppliers. These contracts are generally cancelable by either party with 30 days’ prior written notice. As of December 31, 2017, the minimum future payments on these contracts totaled approximately $634,000. We lease approximately 37,000 square feet of office and lab space for our corporate headquarters in San Diego, California. In October 2017, we amended this lease to extend the expiration date by 88 months from January 2018 to May 2025. Effective February 1, 2018, our monthly rent became $66,000 and it will increase every February by three percent. The amended lease also contains a leasehold improvement allowance of $787,000 and rent abatements of $274,000. We record rent expense on a straight-line basis over the life of the lease; the difference between average rent expense and cash payments for rent is recorded as a deferred liability. As of December 31, 2017, our deferred rent totaled $17,000, which was classified as a current liability. We recorded rent expense of $758,000, $770,000, and $794,000 for the years ended December 31, 2017, 2016, and 2015, respectively. Future minimum payments under the lease are as follows (in thousands): Minimum Year Ending December 31, Payments 2018 $ 716 2019 741 2020 763 2021 786 2022 884 Therafter 2,248 $ 6,138

Capital Stock

Capital Stock	12 Months Ended
	Dec. 31, 2017
Capital [Abstract]
Capital Stock	10. Capital Stock Our certificate of incorporation, as amended, authorizes us to issue 100,000,000 shares of common stock, par value $0.0001 per share, 25,000,000 shares of Class B common stock, par value $0.0001 per share and 5,000,000 shares of undesignated preferred stock, par value $0.0001 per share. As of December 31, 2017 and 2016, 41,245,820 and 42,851,477, respectively, shares of common stock were outstanding and no shares of Class B common stock or undesignated preferred stock were outstanding. Certain shareholders, as well as the holders of our convertible notes, if such convertible notes are converted into common stock, have the right to cause us to file a registration statement that would register the resale of such shares on their behalf and to include their shares in registration statements that we may file on behalf of other stockholders.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	11. Stock-Based Compensation The Plan : Our 2010 Equity Incentive Plan, as amended (the “Plan”), provides for grants of incentive and non-qualified stock options for purchase of our common stock at a price per share equal to the closing market price on the date of grant, and for awards of restricted stock units (“RSUs”) and restricted stock, for which there is no consideration payable by a recipient. An RSU entitles the recipient to one share of our common stock upon vesting. All stock issuances under the Plan are made with new shares from our authorized but unissued common stock. The number of shares reserved under the Plan may be increased annually by up to three percent of our outstanding stock. On January 1, 2017, an additional 1,285,544 shares were added to the Plan, resulting in a total of 9,144,512 shares reserved for issuance under the Plan as of December 31, 2017. Option activity under the Plan is as follows: Options Outstanding Weighted Average Exercise Price Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Balance at December 31, 2014 4,243,425 $ 7.01 Granted 2,152,500 $ 4.50 Cancelled (232,292 ) $ 2.85 Exercised (251,208 ) $ 2.27 Balance at December 31, 2015 5,912,425 $ 6.46 6.50 $ 7,873,000 Granted 570,100 $ 8.22 Cancelled (106,834 ) $ 10.81 Exercised (247,499 ) $ 4.04 Balance at December 31, 2016 6,128,192 $ 6.65 5.94 $ 13,857,000 Granted 897,100 $ 6.80 Cancelled (783,123 ) $ 7.42 Exercised (121,678 ) $ 2.81 Balance at December 31, 2017 6,120,491 $ 6.65 6.00 $ 3,571,000 Exercisable at December 31, 2017 5,153,771 $ 7.03 5.68 $ 2,899,000 Vested at December 31, 2017 3,973,578 $ 7.10 4.72 $ 2,750,000 Employees, non-employee directors, and consultants are eligible to participate in the Plan. For purposes of determining stock-based compensation expense, we include non-employee directors with employees; we account for consultant compensation expense separately. The term of awards granted under the Plan may not exceed ten years. Vesting periods of awards are determined by our board of directors. A majority of the vesting periods of outstanding stock options is four years, with 25 percent vesting on the one-year anniversary of the vesting commencement date and 75 percent vesting in equal monthly installments thereafter. A majority of the options are exercisable at any time but, if exercised prior to vesting, are subject to a lapsing right of repurchase by us at the exercise price until fully vested. As of December 31, 2017 and 2016, no unvested options had been exercised and, therefore, no shares were subject to repurchase. During March 2015, we granted a total of 316,000 options that vest based on achievement of certain performance milestones. We estimated the vesting term for each performance milestone on the date of grant, and on each reporting date thereafter, based on our internal timelines and operating projections. Our estimates of vesting ranged from approximately nine to 30 months at the grant date in March 2015; we estimated the weighted average remaining vesting term to be 12 months as of both December 31, 2017 and 2016. A total of 65 percent of these options had vested as of December 31, 2017. During the years ended December 31, 2017 and 2016, 63,000 and 12,250 unvested options were cancelled, respectively. During 2013, we awarded 87,500 shares of restricted stock; 25 percent of each award vests on each annual anniversary date of the award. As of December 31, 2017, all of these awards had vested and none had been cancelled. RSU activity under the Plan is as follows: RSUs Performance Time Outstanding Based Based Balance at December 31, 2014 — — — Granted 984,200 824,200 160,000 Cancelled — — — Vested — — — Balance at December 31, 2015 984,200 824,200 160,000 Granted 47,800 — 47,800 Cancelled (118,000 ) (118,000 ) — Vested (160,000 ) — (160,000 ) Balance at December 31, 2016 754,000 706,200 47,800 Granted 397,300 162,500 234,800 Cancelled (526,000 ) (479,200 ) (46,800 ) Vested (47,800 ) — (47,800 ) Balance at December 31, 2017 577,500 389,500 188,000 We estimated the vesting term for each performance-based RSU on the award date, and on each reporting date thereafter, based on our internal timelines and operating projections. As of December 31, 2017, we estimated the remaining weighted average vesting term to be 8.1 months for the RSUs granted in 2015 and 6 months for the RSUs granted in 2017. Time-based RSUs generally vest over one year for non-employee directors and ratably over three years for employees. No tax benefits arising from stock-based compensation have been recognized in our consolidated statements of operations through December 31, 2017. Grants and Awards to Employees: We account for option grants, restricted stock awards, and RSUs to employees based on their estimated fair values on the date of grant or award, with the resulting stock-based compensation recorded over the requisite service period on a straight-line basis. The fair value of restricted stock and RSUs is equal to the closing market price of our common stock on the date of award. The fair value of option grants was estimated on the date of grant using the following weighted-average assumptions: Year Ended December 31, 2017 2016 2015 Risk-free interest rate 2.2% 1.6% 1.8% Expected volatility of common stock 65.4% 57.6% 55.6% Expected life in years 6.21 6.13 6.16 Dividend yield 0.0% 0.0% 0.0% The assumed risk-free interest rate was based on the implied yield on a U.S. Treasury zero-coupon issue with a remaining term equal to the expected life of the option. The assumed volatility was calculated from the historical market prices of a selected group of publicly traded companies considered to be our peers; we use peer group data because we have limited historical trading data for our common stock, but adjusted the 2016 volatility upward by approximately ten percent to allow us to move toward using historical trading data for our common stock, which is more volatile than our peer group. In 2017, we began to use our historical trading price of our common stock; our common stock began trading on our IPO date of December 23, 2010, which provides approximately 7 years of history as December 31, 2017. For options that have time-based vesting, the expected option life was calculated using the simplified method under the accounting standard for stock compensation and a ten-year option expiration; we use the simplified method because we do not yet have adequate history as a public company traded on a U.S. stock exchange to establish a reasonable expected life. For options that have performance-based vesting, the expected life was calculated based on our internal timelines and operating projections. The options granted during the years ended December 31, 2017, 2016 and 2015 had a weighted average grant date fair value of $4.15, $4.48 and $2.40, respectively. The aggregate intrinsic value of options exercised during the years ended December 31, 2017, 2016 and 2015 was $362,000, $976,000 and $511,000, respectively. For the options and RSUs that vest upon achievement of performance milestones, we record compensation expense for only those milestones that are probable of being achieved. The vest-date fair value of RSUs that vested during the year ended December 31, 2017 and 2016 was $320,000 and $1.3 million, respectively. No RSUs vested in the year ended December 31, 2015. Stock-based compensation arising from employee options and awards under the Plan is as follows (in thousands): Year Ended December 31, 2017 2016 2015 Research and development expense $ (109 ) $ 1,260 $ 1,502 Selling, general and administrative expense 2,156 3,423 1,905 $ 2,047 $ 4,683 $ 3,407 In the years ended December 31, 2017 and 2016, we reversed stock-based compensation of $1.8 million and $163,000, respectively, related to unvested awards for employees that were terminated. As of December 31, 2017, we had approximately $7.3 million of total unrecognized compensation costs related to unvested employee awards that are expected to be recognized over a weighted average period of 1.7 years. Stock Options to Consultants : We account for stock options granted to consultants at their fair value. Under this method, the fair value is estimated at each reporting date during the vesting period using the Black-Scholes option valuation model. The resulting stock-based compensation expense, or income if the fair value declines in a reporting period, is recorded over the consultant’s service period. Fully vested options to purchase 7,500 shares of common stock were granted to consultants during the year ended December 31, 2016. No options were granted to consultants during the years ended December 31, 2017 or 2015. Consultant stock-based compensation expense is recorded to the financial statement line item for which the consultant’s services are rendered. Stock-based compensation expense arising from consultant options is as follows (in thousands): Year Ended December 31, 2017 2016 2015 Research and development expense $ — $ — $ — Selling, general and administrative expense — 40 27 $ — $ 40 $ 27

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	12. Income Taxes A reconciliation of the tax provision to the amount computed by applying the statutory federal rate to the net income/(loss) is summarized as follows (in thousands): Year Ended December 31, 2017 2016 2015 Federal income taxes at 34% $ 2,426 $ (18,393 ) $ (28,082 ) State income taxes, net of federal benefit (226 ) (1,484 ) (1,513 ) Research and development tax credits (556 ) (889 ) (650 ) Changes in fair value of convertible notes and common ‌stock warrant liability (11,972 ) 8,584 19,308 Increase in valuation allowance (24,704 ) 10,583 8,789 Accrued interest on convertible notes 1,555 698 944 Expiration of state net operating losses — 641 692 State rate adjustment 1,411 — — Tax Cuts and Jobs Act of 2017 31,541 — — Stock-based compensation expense 815 223 287 Other (290 ) 37 225 $ — $ — $ — Our deferred income taxes reflect the net tax effects of temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of our deferred tax assets and liabilities are as follows: December 31, 2017 2016 Net operating loss carryforwards $ 57,278 $ 80,382 Research and development credits 9,636 8,422 Amortization 4,422 4,302 Stock-based compensation expense 3,723 6,766 Depreciation 265 416 Accrued operating expenses 11 22 Debt issuance costs 479 142 Other 196 262 76,010 100,714 Valuation allowance (76,010 ) (100,714 ) $ — $ — As of December 31, 2017, we had aggregate federal and California state net operating loss carryforwards of approximately $221.3 million and $154.6 million, respectively, which may be available to offset future taxable income for income tax purposes. The federal and California net operating loss carryforwards begin to expire in 2019 and 2027, respectively. As of December 31, 2017, we also had federal and California state research tax credit carryforwards of approximately $7.5 million and $6.8 million, respectively. The federal research tax credit carryforwards begin to expire in 2020. The California state research tax carryforwards have no expiration. Under Internal Revenue Code Sections 382 and 383, annual use of our net operating loss and research tax credit carryforwards to offset taxable income may be limited based on cumulative changes in ownership. An analysis of the impact of this provision from December 1, 1999 through December 31, 2017 has been performed and it was determined that, although ownership changes have occurred, the carryovers should be available for use by the Company before they expire, provided we generate sufficient future taxable income. Future ownership changes could result in limitations and may impact the realizability of these loss and credit carryforwards in future periods. On December 22, 2017, new tax reform legislation in the U.S., known as the Tax Cuts and Jobs Act of 2017 (the “Act”) was signed into law. At December 31, 2017, the Company has not yet completed its accounting assessment for the tax effects of the enactment of the Act; however, as described below, the Company has made a reasonable estimate of the effects on the existing deferred tax balances. As a result of the lower enacted corporate tax rate, the Company has remeasured certain deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, which is generally 21%. The provisional amount recorded related to the remeasurement of our deferred tax balance was $31.5 million that is fully offset by a corresponding decrease to our valuation allowance. Staff Accounting Bulletin No. 118 ("SAB 118") was issued to address the application of US GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Act. In accordance with SAB 118, the Company has provisionally determined that there is no deferred tax benefit or expense with respect to the remeasurement of certain deferred tax assets and liabilities due to the full valuation allowance against net deferred tax assets. The Company is still analyzing certain aspects of the Act and refining its calculations, which could potentially affect the measurement of these balances or potentially give rise to new deferred tax amounts. Additional analysis of the law and the impact to the Company will be performed and any impact will be recorded in the respective quarter in 2018. As of December 31, 2017, we had deferred tax assets of $76.0 million and have established a valuation allowance against those deferred tax assets due to the uncertainty surrounding our ability to generate future taxable income to realize those assets. The change in the valuation allowance for the years ended December 31, 2017 and 2016 was ($24.7 million) and $10.6 million, respectively. We recognize a tax benefit from an uncertain tax position when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on the technical merits. Income tax positions must meet a more-likely-than-not recognition at the effective date to be recognized. As of December 31, 2017, the unrecognized tax benefits recorded were approximately $3.6 million. We do not anticipate a significant change in the unrecognized tax benefits within the next 12 months. A reconciliation of the beginning and ending amount of gross unrecognized tax benefits for 2017 and 2016, excluding interest and penalties, is as follows: December 31, 2017 2016 Balance at beginning of year $ 3,345 $ 4,298 Additions (reductions) for prior year tax positions — (1,297 ) Additions for current year tax positions 222 344 $ 3,567 $ 3,345 Due to our valuation allowance position, none of the unrecognized tax benefits, if recognized, will impact our effective tax rate. Our policy is to record interest and penalties within tax expense. As of December 31, 2017 and 2016, we had no accrued interest or penalties related to uncertain tax positions. The Company is subject to taxation in the U.S. federal and state jurisdictions. As of December 31, 2017, the Company is no longer subject to U.S. federal and state examinations by tax authorities for years before 2012 and 2011, respectively. However, to the extent allowed by law, the tax authorities may have the right to examine prior periods where net operating losses were generated and carried forward, and make adjustments up to the amount of the net operating loss carryforward amount. The Company is not currently under IRS, state or local tax examination.

Net Income (Loss) Per Common Sh

Net Income (Loss) Per Common Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Net Income (Loss) Per Common Share	13. Net Income (Loss) Per Common Share Basic net income (loss) per common share is calculated by dividing the net income (loss) attributable to common stockholders by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted average number of common share equivalents outstanding for the period determined using the treasury-stock method and the if-converted method, as applicable. For this calculation, common stock options and restricted stock subject to forfeiture are considered to be common stock equivalents; common stock equivalents are used in the calculation of diluted net loss per share only when their effect is dilutive. Basic net income (loss) per share reconciles to fully diluted net loss per share as follows (dollars in thousands): Year Ended December 31, 2017 2016 2015 Diluted Net Loss: Net income (loss) used for basic net income (loss) per share $ 7,134 $ (54,098 ) $ (82,594 ) Interest expense on 2014 convertible notes 2,202 — — Gain on change in fair value of 2014 convertible notes (30,672 ) — — $ (21,336 ) $ (54,098 ) $ (82,594 ) Weighted Average Shares Used to Compute Diluted Net Loss per Share: Shares used for basic net income (loss) per share 41,811,326 42,120,545 34,680,634 Common share equivalents – assumed conversion of 2014 convertible notes (see Note 7) 11,506,156 — — 53,317,482 42,120,545 34,680,634 The following weighted average shares were excluded from the computations of diluted net loss per share because including them would have been antidilutive. Year Ended December 31, 2017 2016 2015 Weighted Average Shares Excluded: Options to purchase common stock 6,352,118 6,355,093 4,812,372 Unvested restricted stock 5,171 31,528 61,623 Restricted stock units 726,379 882,779 768,908 Warrants to purchase common stock 1,334,749 502,049 7,647,260 Common share equivalents of convertible notes 3,427,047 11,506,156 11,506,156 11,845,464 19,277,605 24,796,319

Retirement Plan

Retirement Plan	12 Months Ended
	Dec. 31, 2017
Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract]
Retirement Plan	14. Retirement Plan In 2003 we adopted a qualified 401(k) profit sharing plan (the “401(k) Plan”) for the benefit of our employees. Employees are eligible to participate in the 401(k) Plan the month following hire and may defer up to the maximum allowed under IRS regulations, on an annual basis. We match 25 percent of an employee’s deferral amount, up to a maximum of four percent of qualified compensation. We may, at our discretion, make additional contributions. Employees are immediately vested in the employer matching contributions. Our contributions to the 401(k) Plan were $45,000, $49,000, and $42,000 for the years ended December 31, 2017, 2016, and 2015, respectively.

Related Parties

Related Parties	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Parties	15. Related Parties Our related parties include the members of our board of directors, investors with five percent or more of our outstanding shares of common stock, and holders of our convertible notes. Other than approved board compensation, the amendment to the 2014 Notes, issuance of the 2017 Notes and warrants and exercise of warrants to purchase common stock (all discussed above), we had no related party transactions during the years ended December 31, 2017 and 2016. See Note 7 Convertible Notes Payable and Warrants to Purchase Common Stock

Selected Quarterly Financial In

Selected Quarterly Financial Information	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Information (unaudited)	16. Selected Quarterly Financial Information The following table presents selected quarterly financial information that has been derived from our unaudited quarterly consolidated financial statements, which, in the opinion of management, include all adjustments (consisting only of normal recurring items) necessary for a fair presentation. The quarterly per share data presented below was calculated separately and may not sum to the annual figures presented in the consolidated financial statements. These operating results are also not necessarily indicative of results for any future period. Quarter Ended Year Ended March 31, June 30, September 30, December 31, December 31, 2017 (unaudited) Revenue $ — $ — $ 17 $ 28 $ 45 Loss from operations (6,066 ) (5,060 ) (4,769 ) (5,434 ) (21,329 ) Gain on change in fair values 8,138 8,178 12,304 7,111 35,731 Net income (loss) 1,424 (503 ) 6,053 160 7,134 Basic net income (loss) per common share $ 0.03 $ (0.01 ) $ 0.15 $ 0.00 $ 0.17 Diluted net loss per common share $ (0.11 ) $ (0.01 ) $ (0.04 ) $ (0.10 ) $ (0.40 ) 2016 (unaudited) Loss from operations $ (7,481 ) $ (7,031 ) $ (6,149 ) $ (6,119 ) $ (26,780 ) Gain (loss) on change in fair values (32,764 ) 2,966 (17,269 ) 21,820 (25,247 ) Net income (loss) (40,798 ) (4,555 ) (23,943 ) 15,198 (54,098 ) Basic net income (loss) per common share $ (1.01 ) $ (0.11 ) $ (0.56 ) $ 0.36 $ (1.28 ) Diluted net loss per common share $ (1.01 ) $ (0.11 ) $ (0.56 ) $ (0.11 ) $ (1.28 ) For the quarterly periods provided above, when the Company recognized net income, diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted average number of common share equivalents outstanding for the period determined using the treasury-stock method and the if-converted method, as applicable. For purpose of this calculation, common stock options and restricted stock subject to forfeiture are considered to be common stock equivalents; common share equivalents are included in the calculation of diluted net loss per share only when their effect is dilutive. Basic net income per share reconciles to fully diluted net loss per share as follows (dollars in thousands): Quarter Ended March 31, 2017 September 30, 2017 December 31, 2017 December 31, 2016 Diluted Net Loss: Net income used for basic net income per share $ 1,424 $ 6,053 $ 160 $ 15,198 Interest expense on 2014 convertible notes payable 538 550 571 531 Gain on change in fair value of 2014 convertible notes payable (8,138 ) (8,741 ) (6,213 ) (21,820 ) $ (6,176 ) $ (2,138 ) $ (5,482 ) $ (6,091 ) Weighted Average Shares Used to Compute Diluted Net Loss per Share: Shares used for basic net income per share 42,838,158 41,197,348 41,245,820 42,747,769 Common share equivalents 11,506,156 11,506,156 11,506,156 11,506,156 54,344,314 52,703,504 52,751,976 54,253,925

Significant Accounting Polici24

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation : We have prepared the accompanying consolidated financial statements in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). The consolidated financial statements include the accounts of REVA and our wholly owned subsidiary, REVA Germany GmbH. All intercompany transactions and balances, if any, have been eliminated in consolidation.
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 amounts reported in the financial statements and accompanying notes. Actual results could differ from our estimates.
Cash Equivalents	Cash Equivalents : We consider all highly liquid investments with original maturities of three months or less at the date of purchase to be cash equivalents. Cash equivalents are carried at cost, which we believe approximates fair value due to the short-term maturities of these investments.
Investment Securities	Investment Securities : Investment securities are marketable equity or debt securities. All of our investment securities are “available-for-sale” securities and carried at fair value. Fair value for securities with short maturities and infrequent secondary market trades typically is determined by using a curve-based evaluation model that utilizes quoted prices for similar securities. The evaluation model takes into consideration the days to maturity, coupon rate and settlement date convention. Net unrealized gains or losses on these securities are included in accumulated other comprehensive loss, which is a separate component of stockholders’ deficit. Realized gains and realized losses are included in other income (expense) while amortization of premiums and accretion of discounts are included in interest income. Interest and dividends on available-for-sale securities are included in interest income. We periodically evaluate our investment securities for impairment. If we determine that a decline in fair value of any investment security is other than temporary, then the cost basis would be written down to fair value and the decline in value would be charged to other expense at that time. Our investment securities are under the custodianship of a major financial institution and consist of certificates of deposit that are insured by the Federal Deposit Insurance Corporation. We have classified all of our available-for-sale investment securities as current assets on our consolidated balance sheets because we consider them to be highly liquid and available for use, if needed, in current operations. As of December 31, 2017, none of our $1.5 million of investment securities had contractual maturity dates of more than one year.
Inventory	Inventory: We received CE Mark approval of our Fantom scaffold on April 3, 2017, at which time we began capitalizing raw material purchases and commercial scaffold production costs to inventory. Inventory is stated at the lower of cost or net realizable value based on the first-in, first-out cost method (“FIFO”). Our policy is to record an estimated allowance against inventory for unsalable, obsolete, or impaired inventory, with a corresponding increase to cost of revenue. We record the cost of products to be used in research and development or clinical trials as research and development expense when inventory is requisitioned for such use.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets : We review our long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable and exceeds its undiscounted future cash flows. The amount of impairment, if any, is determined by comparing an asset’s estimated fair value to the asset’s respective carrying amount. During the years ended December 31, 2017, 2016, and 2015 we determined there were no indications of long-lived asset impairment.
Convertible Notes	Convertible Notes : Convertible notes are analyzed at issue date to determine balance sheet classification, issue discounts or premiums, and embedded or derivative features. Embedded or derivative features are evaluated in accordance with accounting guidance for derivative securities and, if the features give rise to separate accounting, we make an election to account for the notes at cost or at fair value. If fair value accounting is elected on the issue date, we record the difference between the issue price of the notes and their fair value as a gain or loss in our consolidated statement of operations. We remeasure the fair value at each reporting date and record a gain (upon a decrease in fair value) or loss (upon an increase in fair value), as a component of other income (expense) in our consolidated statement of operations. Inputs to the models include the market value of the underlying stock, a life equal to the contractual life of the notes, incremental borrowing rates that correspond to debt with similar credit worthiness, and estimated volatility based on the historical prices of our trading securities. For each periodic valuation, we also make assumptions as to our abilities to test and commercialize our product, to obtain future financings when and if needed, and to comply with the terms and conditions of any outstanding notes payable. Following an analysis of their embedded and derivative features, we elected to utilize fair value accounting for all issues of convertible notes as management believes the convertible notes will be converted into common stock, rather than repaid, and the fair value method of accounting provides a more appropriate value of these liabilities than would be provided under the cost method.
Common Stock Warrants	Common Stock Warrants : The fair value of warrants issued for the purchase of common stock is recorded as a liability whenever warrants call for issuance of registered shares upon exercise, a condition that we may not be able to satisfy at the time of exercise, and which, if not so satisfied, will result in a net settlement of warrants. Until the time warrants are exercised or expire, the fair value is assessed at each reporting date. Any change in value is recorded as a gain or loss component of other income (expense) in our consolidated statement of operations. Inputs to the valuation models are of the same nature as those used to value our convertible notes.
Revenue	Revenue : We received our first order for Fantom in June 2017. We sell Fantom to hospitals; and title and risk of loss transfer upon delivery to these hospitals. We recognize revenue when all of the following four criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery has occurred; (3) the fee is fixed or determinable; and (4) collectability is reasonably assured. We also consider any return or exchange rights. We analyze product reorder rates to evaluate and determine whether return or exchange rights exist and are likely to be exercised. If the revenue recognition criteria are not met, we defer the recognition of revenue by recording deferred revenue until such time that all criteria are met. We recognized $45,000 of revenue during the year ended December 31, 2017. Total billings for shipped product for this period were $203,000; the amount by which total billings for shipped product exceeded recognized revenue was recorded as deferred revenue. Accounts receivable consist of trade receivables recorded upon shipment of product reduced by reserves when necessary for estimated bad debts. Accounts receivable are recorded at the invoiced amount and do not bear interest. Credit is extended based on an evaluation of the customer’s financial condition. The allowance for doubtful accounts is determined based on current customer information and other relevant factors, including specific identification of past due accounts. Once a receivable is deemed to be uncollectible, such balance is charged against the allowance. As of December 31, 2017, our allowance for doubtful accounts was $0.
Research and Development	Research and Development : Research and development costs are expensed as incurred. These costs include salaries, employee benefits, laboratory supplies, consulting services, manufacturing products and services, preclinical and clinical costs, technology license fees, laboratory equipment depreciation, facility costs, and certain indirect costs.
Income Taxes	Income Taxes : We account for income taxes using the asset and liability method, under which the current income tax expense or benefit is the amount of income tax expected to be payable or refundable in the current year. Deferred tax assets and liabilities are recorded for the estimated future tax consequences of temporary differences between the financial statement carrying amounts of assets and liabilities and their respective tax bases, and for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the year in which the temporary differences are expected to be recovered or settled. We evaluate the realizability of our deferred tax assets and establish a valuation allowance when it is more likely than not that all or a portion of our deferred tax assets will not be realized. In making such a determination, we consider all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax planning strategies, and results of recent operations. If we determine that we would be able to realize our deferred tax assets in the future in excess of their net recorded amount, we would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. We account for the uncertainty in income tax components based on tax positions taken or expected to be taken in a tax return. To recognize a benefit, a tax position must be more likely than not to be sustained upon examination by taxing authorities. We do not recognize tax benefits that have a less than 50 percent likelihood of being sustained. Our policy is to recognize interest and tax penalties related to unrecognized tax benefits in income tax expense; no interest or tax penalties on uncertain tax benefits have been recorded through December 31, 2017.
Stock-Based Compensation	Stock-Based Compensation : Stock-based compensation expense is recorded in connection with stock options, restricted stock awards, and restricted stock unit awards (“RSUs”) to employees, directors, and consultants. We have granted stock options, restricted stock, and RSUs that vest based on the passage of time (time-based vesting awards) as well as stock options and RSUs that vest based on achievement of performance milestones (performance-based vesting awards). For time-based vesting stock options granted to employees and directors, we determine compensation expense based on estimated grant date fair values utilizing the Black-Scholes option valuation model. The Black-Scholes model requires the input of assumptions, including volatility, the expected term, and the fair value of the underlying common stock on the date of grant, among other inputs. For time-based vesting restricted stock awards and RSUs, the grant date fair value is equal to the closing market price of our common stock on the date of award. We use the straight-line method to allocate compensation expense to reporting periods over each recipient’s requisite service period, which is generally from one to four years. All stock-based compensation expense is recorded as either research and development or selling, general and administrative expense based on a recipient’s work classification. For performance-based vesting stock options and RSUs, we record compensation expense for only the performance milestones that are probable of being achieved, with such expense recorded on a straight-line basis over the expected vesting period. We reassess our performance-based estimates each reporting period and, if the estimated service period changes, we recognize all remaining compensation expense over the remaining service period and, if the probability of achievement changes to or from “probable,” we recognize the cumulative effect. Whenever an award recipient terminates service prior to achievement of a performance milestone, the recipient’s unvested awards are cancelled and the related compensation expense previously recorded is reversed. For stock options granted to consultants, all of which are time-based vesting, we estimate fair values at the date of grant and at each subsequent reporting period and record compensation expense during the consultant’s service period. We estimate the fair value utilizing the Black-Scholes option valuation model with the same approach to inputs and assumptions as we use to estimate the fair value of employee options, except we use the remaining term as the expected life of the option.
Foreign Currency	Foreign Currency : The functional currency of our subsidiary REVA Germany GmbH is the Euro. Balance sheet accounts of our subsidiary are translated into United States dollars using the exchange rate in effect at the balance sheet date while expenses are translated using the average exchange rate in effect during the period. Gains and losses arising from translation of our subsidiary’s financial statements are recorded to other comprehensive income (loss). These gains and losses, in the aggregate, were insignificant through December 31, 2017.
Concentrations	Concentrations: Financial instruments that potentially subject us to concentrations of credit risk are primarily cash, cash equivalents and investment securities. Investment securities are invested in accordance with our investment policy. Our audit committee approved an investment policy that sets our investment parameters and limitations with objectives of preserving principal and liquidity. Periodically, we maintain deposits at financial institutions in excess of government insured limits. We invest our cash balances in major financial institutions that we believe have high credit quality and have not experienced any losses on such accounts. We do not believe we are exposed to significant credit risk. We require customized components that currently are available from a limited number of sources. We source certain components included in our products from single vendors. As we recently commenced commercial operations, our revenue in 2017 is more concentrated than we expect it to be after we expand commercially. Our top customer represented 26% of our total shipments in 2017. All of our shipments as of December 31, 2017 were made to customers outside of the United States as we only have approval to sell in countries that recognize CE Mark. We maintain inventory at our third-party logistics provider in The Netherlands. As of December 31, 2017, $127,000 of our inventory was held at this location.
Segment Information	Segment Information: We operate in one business segment, which is the development and commercialization of medical devices.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements : We adopted ASU 2016-09, Stock Compensation: Improvements to Employee Share-Based Payment Accounting , effective January 1, 2017. ASU 2016-09 simplifies certain aspects of accounting for stock-based compensation, including the accounting for income taxes, the option to recognize forfeiture credits as they occur rather than as an estimate of future activity, and classifications in the statement of cash flows. Upon the adoption, we recorded a cumulative effect adjustment to increase our accumulated deficit by approximately $53,000, with a corresponding increase to additional paid-in capital, to reverse our forfeiture estimate for unvested awards. All forfeitures occurring after adoption are being recognized in the consolidated statement of operations in the reporting period in which they occur. We had $1.8 million of forfeitures during the year ended December 31, 2017 related to a reduction in force that occurred in July 2017. See Note 11 Stock-Based Compensation .
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements: In May 2014, the Financial Accounting Standards Board, or FASB, issued ASU 2014-09, Revenue from Contracts with Customers, which introduced Accounting Standards Codification 606 , Revenue from Contracts with Customers (“ASC 606”) , an updated standard on revenue recognition. The standard outlines a single comprehensive model to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. Revenue recognized under ASC 606 will represent the consideration an entity expects to be entitled to in exchange for the transfer of goods or services to a customer; it also requires additional disclosures about the nature, amount, timing, and uncertainty of revenue and cash flows arising from customer contracts. The standard permits two methods of adoption: retrospectively to each prior reporting period (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (modified retrospective method). We adopted ASC 606 effective January 1, 2018 and will utilize the modified retrospective method for adoption. The adoption of the standard will not result in a material transition adjustment. Total billings for shipped product for the year ended December 31, 2017 were $203,000. We are in the process of finalizing the new required disclosures. In January 2016, the FASB issued ASU No. 2016-01, “Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities” In February 2016, ASU 2016-02, Leases (Topic 842) In July 2017, ASU 2017-11, Earnings Per Share, Distinguishing Liabilities from Equity, Derivatives and Hedging

Inventory (Tables)

Inventory (Tables)	12 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
Inventory	The Company began capitalizing inventory upon CE Mark approval in the second quarter of 2017. Inventory consisted of the following at December 31, 2017 (in thousands): December 31, 2017 Raw materials $ 255 Work in process 61 Finished goods 329 Excess and obsolete reserve (18 ) $ 627

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Schedule of property and equipment	Property and equipment at December 31, 2017 and 2016 are as follows (in thousands): December 31, 2017 2016 Furniture, office equipment, and software $ 601 $ 655 Laboratory equipment 5,705 6,604 Leasehold improvements 2,422 2,412 8,728 9,671 Accumulated depreciation and amortization (7,236 ) (7,394 ) $ 1,492 $ 2,277

Accrued Expenses and Other Cu27

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Accounts Payable And Accrued Liabilities Current [Abstract]
Summary of accrued expenses and other current liabilities	Accrued expenses and other current liabilities at December 31, 2017 and 2016 are as follows (in thousands): December 31, 2017 2016 Accrued salaries and other employee costs $ 1,296 $ 1,456 Accrued operating expenses 404 519 Accrued use taxes and other 37 198 $ 1,737 $ 2,173

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Summary of fair values of cash equivalents, investments securities, convertible notes and common stock warrant liability	The fair values of our cash equivalents, investment securities, convertible notes and common stock warrant liability are summarized in the following tables (in thousands): December 31, 2017 Total Fair Value Determined Under: Fair Value Level 1 Level 2 Level 3 Assets: Cash equivalents $ 4,388 $ 4,388 $ — $ — Investment securities $ 1,470 $ — $ 1,470 $ — Liabilities: Convertible notes payable $ 99,368 $ — $ — $ 99,368 Common stock warrant liability $ 4,176 $ — $ — $ 4,176 December 31, 2016 Total Fair Value Determined Under: Fair Value Level 1 Level 2 Level 3 Assets: Cash equivalents $ 6,655 $ 6,655 $ — $ — Liabilities: Convertible notes payable $ 91,655 $ — $ — $ 91,655
Summary of weighted average assumptions used to value Level 3 liabilities	A summary of the weighted average assumptions used to value these Level 3 liabilities is as follows: Year Ended December 31, 2017 2016 Market price per share of common stock $ 5.31 $ 7.90 Risk-free interest rate 2.1% 2.0% Expected volatility of common stock 45.0% 79.7% Expected life (in years) 4.37 2.90 Bond yield of equivalent securities 26.5% 27.0%
Summary of reconciliation of convertible notes and common stock warrant liability measured and recorded at fair value on a recurring basis using significant unobservable inputs (Level 3)	A reconciliation of the convertible notes and common stock warrant liability that are measured and recorded at fair value on a recurring basis using significant unobservable inputs (Level 3) is as follows: Convertible Common Stock Notes Payable Warrant Liability Balance at December 31, 2014 $ 37,780 $ 15,389 Total unrealized losses on change in fair value 37,585 19,203 Net settlements upon exercise of warrants — (14,970 ) Balance at December 31, 2015 $ 75,365 $ 19,622 Total unrealized losses on change in fair value 16,290 8,957 Net settlements upon exercise of warrants — (28,579 ) Balance at December 31, 2016 $ 91,655 $ — Net issuances 40,954 6,666 Total unrealized gains on change in fair value (33,241 ) (2,490 ) Balance at December 31, 2017 $ 99,368 $ 4,176

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Schedule of the future minimum payments under the lease	Future minimum payments under the lease are as follows (in thousands): Minimum Year Ending December 31, Payments 2018 $ 716 2019 741 2020 763 2021 786 2022 884 Therafter 2,248 $ 6,138

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Schedule of the option activity under the plan	Option activity under the Plan is as follows: Options Outstanding Weighted Average Exercise Price Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Balance at December 31, 2014 4,243,425 $ 7.01 Granted 2,152,500 $ 4.50 Cancelled (232,292 ) $ 2.85 Exercised (251,208 ) $ 2.27 Balance at December 31, 2015 5,912,425 $ 6.46 6.50 $ 7,873,000 Granted 570,100 $ 8.22 Cancelled (106,834 ) $ 10.81 Exercised (247,499 ) $ 4.04 Balance at December 31, 2016 6,128,192 $ 6.65 5.94 $ 13,857,000 Granted 897,100 $ 6.80 Cancelled (783,123 ) $ 7.42 Exercised (121,678 ) $ 2.81 Balance at December 31, 2017 6,120,491 $ 6.65 6.00 $ 3,571,000 Exercisable at December 31, 2017 5,153,771 $ 7.03 5.68 $ 2,899,000 Vested at December 31, 2017 3,973,578 $ 7.10 4.72 $ 2,750,000
Summary of RSU Activity	RSU activity under the Plan is as follows: RSUs Performance Time Outstanding Based Based Balance at December 31, 2014 — — — Granted 984,200 824,200 160,000 Cancelled — — — Vested — — — Balance at December 31, 2015 984,200 824,200 160,000 Granted 47,800 — 47,800 Cancelled (118,000 ) (118,000 ) — Vested (160,000 ) — (160,000 ) Balance at December 31, 2016 754,000 706,200 47,800 Granted 397,300 162,500 234,800 Cancelled (526,000 ) (479,200 ) (46,800 ) Vested (47,800 ) — (47,800 ) Balance at December 31, 2017 577,500 389,500 188,000
Options Granted
Schedule of the weighted-average assumptions used to estimate fair value of options granted	The fair value of option grants was estimated on the date of grant using the following weighted-average assumptions: Year Ended December 31, 2017 2016 2015 Risk-free interest rate 2.2% 1.6% 1.8% Expected volatility of common stock 65.4% 57.6% 55.6% Expected life in years 6.21 6.13 6.16 Dividend yield 0.0% 0.0% 0.0%
Equity awards to employees
Schedule of stock-based compensation arising from employee options and awards	Stock-based compensation arising from employee options and awards under the Plan is as follows (in thousands): Year Ended December 31, 2017 2016 2015 Research and development expense $ (109 ) $ 1,260 $ 1,502 Selling, general and administrative expense 2,156 3,423 1,905 $ 2,047 $ 4,683 $ 3,407
Equity awards to consultants
Schedule of stock-based compensation arising from employee options and awards	Consultant stock-based compensation expense is recorded to the financial statement line item for which the consultant’s services are rendered. Stock-based compensation expense arising from consultant options is as follows (in thousands): Year Ended December 31, 2017 2016 2015 Research and development expense $ — $ — $ — Selling, general and administrative expense — 40 27 $ — $ 40 $ 27

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of the reconciliation of tax provision to the amount computed by applying statutory federal rate to net income/(loss)	A reconciliation of the tax provision to the amount computed by applying the statutory federal rate to the net income/(loss) is summarized as follows (in thousands): Year Ended December 31, 2017 2016 2015 Federal income taxes at 34% $ 2,426 $ (18,393 ) $ (28,082 ) State income taxes, net of federal benefit (226 ) (1,484 ) (1,513 ) Research and development tax credits (556 ) (889 ) (650 ) Changes in fair value of convertible notes and common ‌stock warrant liability (11,972 ) 8,584 19,308 Increase in valuation allowance (24,704 ) 10,583 8,789 Accrued interest on convertible notes 1,555 698 944 Expiration of state net operating losses — 641 692 State rate adjustment 1,411 — — Tax Cuts and Jobs Act of 2017 31,541 — — Stock-based compensation expense 815 223 287 Other (290 ) 37 225 $ — $ — $ —
Schedule of the significant components of deferred tax assets and liabilities	Our deferred income taxes reflect the net tax effects of temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of our deferred tax assets and liabilities are as follows: December 31, 2017 2016 Net operating loss carryforwards $ 57,278 $ 80,382 Research and development credits 9,636 8,422 Amortization 4,422 4,302 Stock-based compensation expense 3,723 6,766 Depreciation 265 416 Accrued operating expenses 11 22 Debt issuance costs 479 142 Other 196 262 76,010 100,714 Valuation allowance (76,010 ) (100,714 ) $ — $ —
Schedule of the reconciliation of the beginning and ending amount of gross unrecognized tax benefits for period excluding interest and penalties	A reconciliation of the beginning and ending amount of gross unrecognized tax benefits for 2017 and 2016, excluding interest and penalties, is as follows: December 31, 2017 2016 Balance at beginning of year $ 3,345 $ 4,298 Additions (reductions) for prior year tax positions — (1,297 ) Additions for current year tax positions 222 344 $ 3,567 $ 3,345

Net Income (Loss) Per Common 32

Net Income (Loss) Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of basic net income (loss) per share reconciles to fully diluted net loss per share	Basic net income (loss) per share reconciles to fully diluted net loss per share as follows (dollars in thousands): Year Ended December 31, 2017 2016 2015 Diluted Net Loss: Net income (loss) used for basic net income (loss) per share $ 7,134 $ (54,098 ) $ (82,594 ) Interest expense on 2014 convertible notes 2,202 — — Gain on change in fair value of 2014 convertible notes (30,672 ) — — $ (21,336 ) $ (54,098 ) $ (82,594 ) Weighted Average Shares Used to Compute Diluted Net Loss per Share: Shares used for basic net income (loss) per share 41,811,326 42,120,545 34,680,634 Common share equivalents – assumed conversion of 2014 convertible notes (see Note 7) 11,506,156 — — 53,317,482 42,120,545 34,680,634
Schedule of weighted average shares excluded from the computation of diluted net loss per share	The following weighted average shares were excluded from the computations of diluted net loss per share because including them would have been antidilutive. Year Ended December 31, 2017 2016 2015 Weighted Average Shares Excluded: Options to purchase common stock 6,352,118 6,355,093 4,812,372 Unvested restricted stock 5,171 31,528 61,623 Restricted stock units 726,379 882,779 768,908 Warrants to purchase common stock 1,334,749 502,049 7,647,260 Common share equivalents of convertible notes 3,427,047 11,506,156 11,506,156 11,845,464 19,277,605 24,796,319

Selected Quarterly Financial 33

Selected Quarterly Financial Information (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of the selected quarterly financial information	Quarter Ended Year Ended March 31, June 30, September 30, December 31, December 31, 2017 (unaudited) Revenue $ — $ — $ 17 $ 28 $ 45 Loss from operations (6,066 ) (5,060 ) (4,769 ) (5,434 ) (21,329 ) Gain on change in fair values 8,138 8,178 12,304 7,111 35,731 Net income (loss) 1,424 (503 ) 6,053 160 7,134 Basic net income (loss) per common share $ 0.03 $ (0.01 ) $ 0.15 $ 0.00 $ 0.17 Diluted net loss per common share $ (0.11 ) $ (0.01 ) $ (0.04 ) $ (0.10 ) $ (0.40 ) 2016 (unaudited) Loss from operations $ (7,481 ) $ (7,031 ) $ (6,149 ) $ (6,119 ) $ (26,780 ) Gain (loss) on change in fair values (32,764 ) 2,966 (17,269 ) 21,820 (25,247 ) Net income (loss) (40,798 ) (4,555 ) (23,943 ) 15,198 (54,098 ) Basic net income (loss) per common share $ (1.01 ) $ (0.11 ) $ (0.56 ) $ 0.36 $ (1.28 ) Diluted net loss per common share $ (1.01 ) $ (0.11 ) $ (0.56 ) $ (0.11 ) $ (1.28 )
Schedule of basic net income per share reconciles to fully diluted net loss per share	Basic net income per share reconciles to fully diluted net loss per share as follows (dollars in thousands): Quarter Ended March 31, 2017 September 30, 2017 December 31, 2017 December 31, 2016 Diluted Net Loss: Net income used for basic net income per share $ 1,424 $ 6,053 $ 160 $ 15,198 Interest expense on 2014 convertible notes payable 538 550 571 531 Gain on change in fair value of 2014 convertible notes payable (8,138 ) (8,741 ) (6,213 ) (21,820 ) $ (6,176 ) $ (2,138 ) $ (5,482 ) $ (6,091 ) Weighted Average Shares Used to Compute Diluted Net Loss per Share: Shares used for basic net income per share 42,838,158 41,197,348 41,245,820 42,747,769 Common share equivalents 11,506,156 11,506,156 11,506,156 11,506,156 54,344,314 52,703,504 52,751,976 54,253,925

Description of Business (Detail

Description of Business (Details)	12 Months Ended
	Dec. 31, 2017itemCountryPatient	Dec. 31, 2010
Description Of Business [Abstract]
Number of patients enrolled in a clinical trial of bioresorbable stent product | item	247
Number of countries | Country	8
Number of patients data used | Patient	117
Common Stock Conversion Rate		10

Capital Resources and Basis o35

Capital Resources and Basis of Presentation (Details) - USD ($)	1 Months Ended
	Nov. 30, 2014	Dec. 31, 2017	Dec. 31, 2016
Capital Resources And Basis Of Presentation [Line Items]
Accumulated deficit		$ 382,157,000	$ 389,238,000
Cash cash equivalents and investment securities		20,000,000
Convertible Notes
Capital Resources And Basis Of Presentation [Line Items]
Debt instrument face amount or principal amount		72,100,000
Accrued interest on the convertible notes		8,800,000
2014 Notes | Convertible Notes
Capital Resources And Basis Of Presentation [Line Items]
Notes, maturity date	Nov. 14, 2019
Debt instrument face amount or principal amount	$ 100,000
Accrued interest on the convertible notes		$ 8,800,000	$ 4,200,000

Significant Accounting Polici36

Significant Accounting Policies (Details)	3 Months Ended		12 Months Ended
	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)segment	Jan. 01, 2017USD ($)
Significant Accounting Policies [Line Items]
Investment securities with contractual maturity of more than one year	$ 1,500,000		$ 1,500,000
Revenue	28,000	$ 17,000	45,000
Total billings for shipped product			203,000
Allowance for doubtful accounts receivable	0		0
Interest or tax penalties on uncertain tax benefits			$ 0
Percentage of customer represented our shipments			26.00%
Inventory	627,000		$ 627,000
Number of business segment | segment			1
ASU 2016-09
Significant Accounting Policies [Line Items]
Effect of accumulated deficit				$ 53,000
Effect of accumulated deficit due to forfeiture			$ 1,800,000
ASU 2014-09
Significant Accounting Policies [Line Items]
Total billings for shipped product			203,000
Netherlands | Third-party Logistics Provider
Significant Accounting Policies [Line Items]
Inventory	$ 127,000		$ 127,000
Minimum
Significant Accounting Policies [Line Items]
Stock-based compensation, requisite service period			1 year
Maximum
Significant Accounting Policies [Line Items]
Stock-based compensation, requisite service period			4 years

Inventory (Details)

Inventory (Details) $ in Thousands	Dec. 31, 2017USD ($)
Inventory Disclosure [Abstract]
Raw materials	$ 255
Work in process	61
Finished goods	329
Excess and obsolete reserve	(18)
Inventory	$ 627

Property and Equipment (Details

Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2017
Minimum
Property Plant And Equipment [Line Items]
Property and equipment, useful life	3 years
Maximum
Property Plant And Equipment [Line Items]
Property and equipment, useful life	5 years

Property and Equipment (Detai39

Property and Equipment (Details 1) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 8,728	$ 9,671
Accumulated depreciation and amortization	(7,236)	(7,394)
Property and equipment, net	1,492	2,277
Furniture, office equipment, and software
Property Plant And Equipment [Line Items]
Property and equipment, gross	601	655
Laboratory equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	5,705	6,604
Leasehold improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 2,422	$ 2,412

Accrued Expenses and Other Cu40

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts Payable And Accrued Liabilities Current [Abstract]
Accrued salaries and other employee costs	$ 1,296	$ 1,456
Accrued operating expenses	404	519
Accrued use taxes and other	37	198
Accrued expenses and other current liabilities, total	$ 1,737	$ 2,173

Convertible Notes and Warrant41

Convertible Notes and Warrants to Purchase Common Stock (Details)	1 Months Ended				2 Months Ended	12 Months Ended
	Jun. 30, 2017USD ($)item	May 31, 2017USD ($)item	Feb. 12, 2016USD ($)	Nov. 30, 2014USD ($)sharesitem$ / shares	Jun. 30, 2017USD ($)shares	Dec. 31, 2017USD ($)shares$ / shares	Dec. 31, 2016USD ($)$ / shares	Dec. 31, 2015USD ($)$ / shares
Repurchase of common stock, value						$ 12,493,000
Gain (loss) on change in fair value of convertible notes and warrant liability						35,731,000	$ (25,247,000)	$ (56,788,000)
Interest on convertible notes						6,690,000	$ 2,053,000	$ 1,904,000
Warrants exercise price | $ / shares							$ 2.6073	$ 2.17275
Loss on issuance of convertible notes and warrants						(520,000)
2017 Notes
Transaction costs						2,100,000
2017 Notes | Warrants to purchase common stock
Convertible notes						$ 4,200,000
Warrants issued to purchase common stock | shares					2,119,500
Warrants useful life						5 years
Warrants exercise price | $ / shares						$ 5
2017 Notes | Maximum | Warrants to purchase common stock
Warrants exercise price | $ / shares						$ 7.212
2014 Notes
Number of convertible notes | item				250
Cash proceeds from Notes and warrants				$ 25,000,000
Convertible notes						$ 61,000,000	$ 91,700,000
2014 Notes | Warrants to purchase common stock
Change in fair value of warrants			$ 9,000,000
Convertible Notes
Debt instrument face amount or principal amount						$ 72,100,000
Repurchase of common stock, shares | shares						1,732,260
Convertible rate into common stock | $ / shares						$ 7.212
Repurchase of common stock, value						$ 12,500,000
Interest on convertible notes						4,600,000	2,100,000	$ 1,900,000
Accrued interest on the convertible notes						$ 8,800,000
Convertible Notes | 2017 Notes
Number of convertible notes | item	133	338
Debt instrument face amount or principal amount	$ 100,000	$ 100,000			$ 100,000
Cash proceeds from Notes and warrants					$ 47,100,000
Convertible rate into common stock | $ / shares						$ 8.655
Transaction costs						$ 2,100,000
Net cash proceeds, before transaction costs						$ 32,500,000
Number of converted shares of common stock | shares						5,441,941
Convertible maturity term						5 years
Interest rate (as a percent) accrued on notes						8.00%
Redemption date of notes						Nov. 4, 2019
Number of days written notice for redemption						30 days
Convertible notes						$ 38,400,000
Gain (loss) on change in fair value of convertible notes and warrant liability						(8,700,000)
Accrued interest on the convertible notes						8,800,000	4,200,000
Convertible notes and warrants						47,600,000
Loss on issuance of convertible notes and warrants						$ (500,000)
Convertible Notes | 2017 Notes | Minimum
Convertible rate into common stock | $ / shares						$ 7.212
Convertible Notes | 2014 Notes
Debt instrument face amount or principal amount				$ 100,000
Convertible rate into common stock | $ / shares				$ 2.17275
Number of converted shares of common stock | shares				11,506,156
Interest rate (as a percent) accrued on notes				7.54%
Gain (loss) on change in fair value of convertible notes and warrant liability						$ 36,000,000
Notes, maturity date				Nov. 14, 2019
Accrued interest on the convertible notes						$ 8,800,000	$ 4,200,000

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets:
Cash equivalents	$ 4,388	$ 6,655
Investment securities	1,470
Liabilities:
Convertible notes payable	99,368	91,655
Common stock warrant liability	4,176
Level 1
Assets:
Cash equivalents	4,388	6,655
Level 2
Assets:
Investment securities	1,470
Level 3
Liabilities:
Convertible notes payable	99,368	$ 91,655
Common stock warrant liability	$ 4,176

Fair Value Measurements (Deta43

Fair Value Measurements (Details 1) - Level 3 - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Market price per share of common stock	$ 5.31	$ 7.90
Risk-free interest rate	2.10%	2.00%
Expected volatility of common stock	45.00%	79.70%
Expected life (in years)	4 years 4 months 13 days	2 years 10 months 24 days
Bond yield of equivalent securities	26.50%	27.00%

Fair Value Measurements (Deta44

Fair Value Measurements (Details 2)	12 Months Ended
	Dec. 31, 2017shares
2014 Notes
Number of converted shares of common stock	11,506,156

Fair Value Measurements (Deta45

Fair Value Measurements (Details 3) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common Stock Warrant Liability
Beginning balance		$ 19,622	$ 15,389
Net issuances	$ 6,666
Total unrealized losses (gains) on change in fair value	(2,490)	8,957	19,203
Net settlements upon exercise of warrants		(28,579)	(14,970)
Ending balance	4,176		19,622
Convertible Notes
Beginning balance	91,655	75,365	37,780
Net issuances	40,954
Total unrealized losses (gains) on change in fair value	(33,241)	16,290	37,585
Ending balance	$ 99,368	$ 91,655	$ 75,365

Commitments and Contingencies46

Commitments and Contingencies (Details)	1 Months Ended	12 Months Ended
	Oct. 31, 2017USD ($)	Dec. 31, 2017USD ($)ft²$ / item	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Commitment And Contingencies [Line Items]
Annual license fees		$ 175,000
Other payments of royalty agreement occur during commercialization		950,000
Contingent license fee payable only upon a change in ownership of the company		350,000
Long-term accrued liability related to certain technology		$ 500,000
Contract cancelable period with prior written notice		30 days
Minimum future payments on contracts		$ 634,000
Area of land | ft²		37,000
Operating lease, extension period	88 months
Operating lease, expiration date	May 31, 2025
Operating lease, monthly rent	$ 66,000
Percentage of annual increase in lease rent	3.00%
Leasehold improvements allowance	$ 787,000
Rent abatement	$ 274,000
Deferred rent recorded in Current liability		$ 17,000
Rent expense		$ 758,000	$ 770,000	$ 794,000
Minimum
Commitment And Contingencies [Line Items]
Royalty payment per unit (in dollar per unit) | $ / item		15
Maximum
Commitment And Contingencies [Line Items]
Royalty payment per unit (in dollar per unit) | $ / item		50
License provisions for escalating minimum royalties		$ 2,200,000
Milestone amounts paid to the licensors (as a percent)		40.00%
Annual payments to extend filing periods related to certain technology		$ 300,000
Expected annual deferred payments to extend filing periods related to certain technology		$ 250,000

Commitments and Contingencies47

Commitments and Contingencies (Details 2) $ in Thousands	Dec. 31, 2017USD ($)
Minimum Lease Payments:
2,018	$ 716
2,019	741
2,020	763
2,021	786
2,022	884
Therafter	2,248
Total	$ 6,138

Capital Stock (Details)

Capital Stock (Details) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Class Of Stock [Line Items]
Common stock, shares authorized	100,000,000	100,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Undesignated preferred stock, shares authorized	5,000,000
Undesignated preferred stock, par value	$ 0.0001
Common stock, shares outstanding	41,245,820	42,851,477
Undesignated preferred stock, shares outstanding	0	0
Class B common stock
Class Of Stock [Line Items]
Common stock, shares authorized	25,000,000
Common stock, par value (in dollars per share)	$ 0.0001
Common stock, shares outstanding	0	0

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - USD ($)	Jan. 01, 2017	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2013
Stock-Based Compensation
Options, granted (in shares)			897,100	570,100	2,152,500
Unrecognized compensation cost			$ 7,300,000
Unrecognized compensation cost related to unvested employee awards, period for recognition			1 year 8 months 12 days
Performance-based awards
Stock-Based Compensation
Vesting percentage			65.00%
Options, granted (in shares)		316,000
Options cancelled (in shares)			63,000	12,250
Shares of restricted stock cancelled			479,200	118,000
Reversal of stock-based compensation expense related to termination of unvested awards			$ 1,800,000	$ 163,000
RSUs
Stock-Based Compensation
Shares of restricted stock cancelled			526,000	118,000
RSUs vested			47,800	160,000
Time-based RSUs
Stock-Based Compensation
Shares of restricted stock cancelled			46,800
RSUs vested			47,800	160,000
Equity awards to employees
Stock-Based Compensation
Term of options granted under the plan			10 years
Percentage of volatility upward adjustment			10.00%
Historical trading period			7 years
Dividend yield (as a percent)			0.00%
Weighted average grant date fair value (in dollars per share)			$ 4.15	$ 4.48	$ 2.40
Intrinsic value of options exercised			$ 362,000	$ 976,000	$ 511,000
Vest-date fair value of RSUs			$ 320,000	$ 1,300,000
RSUs vested					0
Equity awards to consultants
Stock-Based Compensation
Options, granted (in shares)			0	7,500	0
2010 Equity Incentive Plan
Stock-Based Compensation
Employee share of common stock upon vesting			1
Number of shares added to the plan	1,285,544
Total number of shares in reserve with additional shares under the Plan			9,144,512
Vesting periods			4 years
Number of unvested options exercised			0	0
Tax benefits from stock based compensation			$ 0
2010 Equity Incentive Plan | Restricted stock
Stock-Based Compensation
Shares of restricted stock awarded						87,500
Annual vesting percent						25.00%
Shares of restricted stock cancelled			0
2010 Equity Incentive Plan | Time-based RSUs | Non-Employee Directors
Stock-Based Compensation
Vesting periods			1 year
2010 Equity Incentive Plan | Time-based RSUs | Employees
Stock-Based Compensation
Vesting periods			3 years
2010 Equity Incentive Plan | Share-based Compensation Award, Tranche One
Stock-Based Compensation
Vesting percentage			25.00%
2010 Equity Incentive Plan | Share-based Compensation Award, Tranche Two
Stock-Based Compensation
Vesting percentage			75.00%
Maximum | Performance-based awards
Stock-Based Compensation
Vesting periods		30 months
Maximum | 2010 Equity Incentive Plan
Stock-Based Compensation
Increment in the number of shares reserved under the Plan annually (as a percent)	3.00%
Term of options granted under the plan			10 years
Minimum | Performance-based awards
Stock-Based Compensation
Vesting periods		9 months
Weighted Average | Performance-based awards
Stock-Based Compensation
Vesting periods			12 months	12 months
Weighted Average | 2010 Equity Incentive Plan | RSUs | Granted in 2015
Stock-Based Compensation
Vesting periods			8 months 3 days
Weighted Average | 2010 Equity Incentive Plan | RSUs | Granted in 2017
Stock-Based Compensation
Vesting periods			6 months

Stock-Based Compensation (Det50

Stock-Based Compensation (Details 1) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Options Outstanding
Balance at the beginning of period (in shares)	6,128,192	5,912,425	4,243,425
Granted (in shares)	897,100	570,100	2,152,500
Cancelled (in shares)	(783,123)	(106,834)	(232,292)
Exercised (in shares)	(121,678)	(247,499)	(251,208)
Balance at the end of period (in shares)	6,120,491	6,128,192	5,912,425
Exercisable at end of year (in shares)	5,153,771
Vested at end of year (in shares)	3,973,578
Weighted Average Exercise Price
Balance at the beginning of period (in dollars per share)	$ 6.65	$ 6.46	$ 7.01
Granted (in dollars per share)	6.80	8.22	4.50
Cancelled (in dollars per share)	7.42	10.81	2.85
Exercised (in dollars per share)	2.81	4.04	2.27
Balance at the end of period (in dollars per share)	6.65	$ 6.65	$ 6.46
Exercisable at end of year (in dollars per share)	7.03
Vested at end of year (in dollars per share)	$ 7.10
Weighted Average Remaining Contractual Term
Balance at end of year	6 years	5 years 11 months 8 days	6 years 6 months
Exercisable at end of year	5 years 8 months 4 days
Vested at end of year	4 years 8 months 19 days
Aggregate Intrinsic Value
Balance at end of year (in dollars)	$ 3,571,000	$ 13,857,000	$ 7,873,000
Exercisable at end of year (in dollars)	2,899,000
Vested at end of year (in dollars)	$ 2,750,000

Stock-Based Compensation (Det51

Stock-Based Compensation (Details 2) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
RSUs
Stock-Based Compensation
Beginning balance	754,000	984,200
Granted	397,300	47,800	984,200
Cancelled	(526,000)	(118,000)
Vested	(47,800)	(160,000)
Ending balance	577,500	754,000	984,200
Performance Based
Stock-Based Compensation
Beginning balance	706,200	824,200
Granted	162,500		824,200
Cancelled	(479,200)	(118,000)
Ending balance	389,500	706,200	824,200
Time Based
Stock-Based Compensation
Beginning balance	47,800	160,000
Granted	234,800	47,800	160,000
Cancelled	(46,800)
Vested	(47,800)	(160,000)
Ending balance	188,000	47,800	160,000

Stock-Based Compensation (Det52

Stock-Based Compensation (Details 3) - Employee Stock Option	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock-Based Compensation
Risk-free interest rate	2.20%	1.60%	1.80%
Expected volatility of common stock	65.40%	57.60%	55.60%
Expected life in years	6 years 2 months 15 days	6 years 1 month 17 days	6 years 1 month 28 days
Dividend yield	0.00%	0.00%	0.00%

Stock-Based Compensation (Det53

Stock-Based Compensation (Details 4) - Equity awards to employees - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	$ 2,047	$ 4,683	$ 3,407
Research and development expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	(109)	1,260	1,502
Selling, general and administrative expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	$ 2,156	$ 3,423	$ 1,905

Stock-Based Compensation (Det54

Stock-Based Compensation (Details 5) - Equity awards to consultants - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 40	$ 27
Selling, general and administrative expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 40	$ 27

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal income taxes at 34%	$ 2,426	$ (18,393)	$ (28,082)
State income taxes, net of federal benefit	(226)	(1,484)	(1,513)
Research and development tax credits	(556)	(889)	(650)
Changes in fair value of convertible notes and common stock warrant liability	(11,972)	8,584	19,308
Increase in valuation allowance	(24,704)	10,583	8,789
Accrued interest on convertible notes	1,555	698	944
Expiration of state net operating losses		641	692
State rate adjustment	1,411
Tax Cuts and Jobs Act of 2017	31,541
Stock-based compensation expense	815	223	287
Other	$ (290)	$ 37	$ 225

Income Taxes (Details) (Parenth

Income Taxes (Details) (Parenthetical)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal income tax rate	34.00%	34.00%	34.00%

Income Taxes (Details 1)

Income Taxes (Details 1) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 57,278	$ 80,382
Research and development credits	9,636	8,422
Amortization	4,422	4,302
Stock-based compensation expense	3,723	6,766
Depreciation	265	416
Accrued operating expenses	11	22
Debt issuance costs	479	142
Other	196	262
Deferred Tax Assets	76,010	100,714
Valuation allowance	$ (76,010)	$ (100,714)

Income Taxes (Details 2)

Income Taxes (Details 2) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Federal income tax rate		34.00%	34.00%	34.00%
Tax Cuts and Jobs Act of 2017		$ 31,541,000
Remeasurement of deferred tax balance accordance with SAB118		0
Deferred tax assets		76,010,000	$ 100,714,000
Change in valuation allowance		(24,700,000)	10,600,000
Unrecognized tax benefits		3,567,000	3,345,000	$ 4,298,000
Unrecognized tax benefit that would impact effective tax rate		0
Accrued interest or penalties related to uncertain tax positions		0	$ 0
Scenario, Plan
Operating Loss Carryforwards [Line Items]
Federal income tax rate	21.00%
Domestic Country
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards		$ 221,300,000
Net operating loss expiration year		2,019
Research tax credit carryforward, amount		$ 7,500,000
Tax Credit Carryforward, Expiration Year		2,020
California
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards		$ 154,600,000
Net operating loss expiration year		2,027
Research tax credit carryforward, amount		$ 6,800,000

Income Taxes (Details 3)

Income Taxes (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 3,345	$ 4,298
Additions (reductions) for prior year tax positions		(1,297)
Additions for current year tax positions	222	344
Balance at end of year	$ 3,567	$ 3,345

Net Income (Loss) Per Common 60

Net Income (Loss) Per Common Share (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Diluted Net Loss:
Net income (loss)	$ 160	$ 6,053	$ (503)	$ 1,424	$ 15,198	$ (23,943)	$ (4,555)	$ (40,798)	$ 7,134	$ (54,098)	$ (82,594)
Interest expense on 2014 convertible notes	571	550		538	531				2,202
Gain on change in fair value of 2014 convertible notes	(6,213)	(8,741)		(8,138)	(21,820)				(30,672)
Diluted Net Loss	$ (5,482)	$ (2,138)		$ (6,176)	$ (6,091)				$ (21,336)	$ (54,098)	$ (82,594)
Weighted Average Shares Used to Compute Diluted Net Loss per Share:
Shares used for basic net income (loss) per share	41,245,820	41,197,348		42,838,158	42,747,769				41,811,326	42,120,545	34,680,634
Common share equivalents – assumed conversion of 2014 convertible notes	11,506,156	11,506,156		11,506,156	11,506,156				11,506,156
Weighted Average Shares Used to Compute Diluted Net Loss Per Share	52,751,976	52,703,504		54,344,314	54,253,925				53,317,482	42,120,545	34,680,634

Net Income (Loss) Per Common 61

Net Income (Loss) Per Common Share (Details 1) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Weighted Average Shares Excluded:
Total weighted average shares excluded	11,845,464	19,277,605	24,796,319
Options to purchase common stock
Weighted Average Shares Excluded:
Total weighted average shares excluded	6,352,118	6,355,093	4,812,372
Unvested restricted stock
Weighted Average Shares Excluded:
Total weighted average shares excluded	5,171	31,528	61,623
Restricted stock units
Weighted Average Shares Excluded:
Total weighted average shares excluded	726,379	882,779	768,908
Warrants to purchase common stock
Weighted Average Shares Excluded:
Total weighted average shares excluded	1,334,749	502,049	7,647,260
Common share equivalents from convertible notes
Weighted Average Shares Excluded:
Total weighted average shares excluded	3,427,047	11,506,156	11,506,156

Retirement Plan (Details)

Retirement Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Plan
Matching contributions equal to the percentage of the employee's contribution	25.00%
Employer matching contribution, (as a percent)	4.00%
Contributions by employer	$ 45,000	$ 49,000	$ 42,000

Related Parties (Details)

Related Parties (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Minimum
Related Party Transaction
Ownership percentage of outstanding securities required to be considered as related party	5.00%
Director
Related Party Transaction
Related party transaction expenses	$ 0	$ 0

Selected Quarterly Financial 64

Selected Quarterly Financial Information (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 28,000	$ 17,000							$ 45,000
Loss from operations	(5,434,000)	(4,769,000)	$ (5,060,000)	$ (6,066,000)	$ (6,119,000)	$ (6,149,000)	$ (7,031,000)	$ (7,481,000)	(21,329,000)	$ (26,780,000)	$ (23,970,000)
Gain (loss) on change in fair values	7,111,000	12,304,000	8,178,000	8,138,000	21,820,000	(17,269,000)	2,966,000	(32,764,000)	35,731,000	(25,247,000)
Net income (loss)	$ 160,000	$ 6,053,000	$ (503,000)	$ 1,424,000	$ 15,198,000	$ (23,943,000)	$ (4,555,000)	$ (40,798,000)	$ 7,134,000	$ (54,098,000)	$ (82,594,000)
Basic net income (loss) per common share	$ 0	$ 0.15	$ (0.01)	$ 0.03	$ 0.36	$ (0.56)	$ (0.11)	$ (1.01)	$ 0.17	$ (1.28)	$ (2.38)
Diluted net loss per common share	$ (0.10)	$ (0.04)	$ (0.01)	$ (0.11)	$ (0.11)	$ (0.56)	$ (0.11)	$ (1.01)	$ (0.40)	$ (1.28)	$ (2.38)

Selected Quarterly Financial 65

Selected Quarterly Financial Information - Net Income Per Common Share (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Diluted Net Loss:
Net income (loss)	$ 160	$ 6,053	$ (503)	$ 1,424	$ 15,198	$ (23,943)	$ (4,555)	$ (40,798)	$ 7,134	$ (54,098)	$ (82,594)
Interest expense on 2014 convertible notes payable	571	550		538	531				2,202
Gain on change in fair value of 2014 convertible notes payable	(6,213)	(8,741)		(8,138)	(21,820)				(30,672)
Diluted Net Loss	$ (5,482)	$ (2,138)		$ (6,176)	$ (6,091)				$ (21,336)	$ (54,098)	$ (82,594)
Weighted Average Shares Used to Compute Diluted Net Loss per Share:
Shares used for basic net income per share	41,245,820	41,197,348		42,838,158	42,747,769				41,811,326	42,120,545	34,680,634
Common share equivalents	11,506,156	11,506,156		11,506,156	11,506,156				11,506,156
Weighted Average Shares Used to Compute Diluted Net Loss Per Share	52,751,976	52,703,504		54,344,314	54,253,925				53,317,482	42,120,545	34,680,634