scPharmaceuticals (SCPH) 10-Q 8 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 07, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Trading Symbol	SCPH
Entity Registrant Name	SCPHARMACEUTICALS INC.
Entity Central Index Key	0001604950
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		18,580,430

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 83,378	$ 89,478
Prepaid expenses	1,770	1,757
VAT receivable	494	479
Other current assets	169	179
Total current assets	85,811	91,893
Restricted cash	182	182
Property and equipment, net	154	164
Right-of-use lease assets - operating, net	1,427	1,506
Deposits and other assets	13	10
Total assets	87,587	93,755
Current liabilities
Accounts payable	221	587
Accrued expenses	5,474	2,922
Term loan, short term	4,035	2,811
Current portion of lease obligation - operating	366	353
Total current liabilities	10,096	6,673
Term loan, long term	5,649	6,826
Long term lease obligation - operating	1,255	1,353
Other liabilities	189	159
Total liabilities	17,189	15,011
Commitments and contingencies (Note 9)
Stockholders’ equity
Preferred stock, $0.0001 par value; 10,000,000 shares authorized and no shares issued and outstanding
Common stock, $0.0001 par value; 150,000,000 shares authorized as of March 31, 2019; 18,569,289 and 18,580,430 shares issued and outstanding as of December 31, 2018 and March 31, 2019, respectively	2	2
Additional paid-in capital	175,574	175,201
Accumulated deficit	(105,178)	(96,459)
Total stockholders’ equity	70,398	78,744
Total liabilities and stockholders’ equity	$ 87,587	$ 93,755

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001
Common stock, shares authorized	150,000,000
Common stock, shares issued	18,580,430	18,569,289
Common stock, shares outstanding	18,580,430	18,569,289

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating expenses:
Research and development	$ 6,524	$ 4,048
General and administrative	2,323	4,651
Total operating expenses	8,847	8,699
Loss from operations	(8,847)	(8,699)
Other expense	(8)	(42)
Interest income	490	351
Interest expense	(354)	(342)
Net loss and comprehensive loss	$ (8,719)	$ (8,732)
Net loss per share — basic and diluted	$ (0.47)	$ (0.47)
Weighted average common shares outstanding — basic and diluted	18,575,726	18,535,432

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Beginning Balance at Dec. 31, 2017	$ 105,997	$ 2	$ 173,011	$ (67,016)
Beginning Balance, Shares at Dec. 31, 2017		18,534,240
Net loss	(8,732)			(8,732)
Issuance of common stock upon exercise of stock options	56		56
Issuance of common stock upon exercise of stock options, Shares		7,606
Vesting of restricted stock	1		1
Vesting of restricted stock, Shares		366
Stock-based compensation	622		622
Ending Balance at Mar. 31, 2018	97,944	$ 2	173,690	(75,748)
Ending Balance, Shares at Mar. 31, 2018		18,542,212
Beginning Balance at Dec. 31, 2018	78,744	$ 2	175,201	(96,459)
Beginning Balance, Shares at Dec. 31, 2018		18,569,289
Net loss	(8,719)			(8,719)
Issuance of common stock upon exercise of stock options	$ 18		18
Issuance of common stock upon exercise of stock options, Shares	11,141	11,141
Stock-based compensation	$ 355		355
Ending Balance at Mar. 31, 2019	$ 70,398	$ 2	$ 175,574	$ (105,178)
Ending Balance, Shares at Mar. 31, 2019		18,580,430

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities
Net loss	$ (8,719,000)	$ (8,732,000)
Adjustments to reconcile net loss to cash used in operating activities
Depreciation expense	10,000	10,000
Amortization expense - right-of-use leased assets - operating	79,000	71,000
Stock-based compensation	355,000	622,000
Non-cash interest expense	80,000	90,000
Changes in operating assets and liabilities
Prepaid expenses and other assets	(19,000)	(703,000)
Accounts payable, accrued expenses and other liabilities	2,096,000	(432,000)
Net cash used in operating activities	(6,118,000)	(9,074,000)
Cash flows from financing activities
Proceeds from the exercise of vested stock options	18,000	56,000
Net cash provided by financing activities	18,000	56,000
Net decrease in cash, cash equivalents and restricted cash	(6,100,000)	(9,018,000)
Cash, cash equivalents and restricted cash at beginning of period	89,660,000	118,480,000
Cash, cash equivalents and restricted cash at end of period	83,560,000	109,462,000
Supplemental cash flow information
Interest paid	274,000	252,000
Taxes paid	$ 166,000	$ 70,000

Description of Business and Bas

Description of Business and Basis of Presentation	3 Months Ended
	Mar. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business and Basis of Presentation	1. Description of Business and Basis of Presentation Description of Business scPharmaceuticals LLC was formed as a Limited Liability Company under the laws of the State of Delaware on February 19, 2013. On March 24, 2014, scPharmaceuticals LLC was converted to a Delaware corporation and changed its name to scPharmaceuticals Inc. (“the Company”). The Company is a pharmaceutical company focused on developing and commercializing products that have the potential to transform the way therapy is delivered, advance patient care and reduce healthcare costs. The Company’s proprietary platform is designed to enable the subcutaneous administration of therapies that have previously been limited to intravenous, or IV, delivery. The Company’s headquarters and primary place of business is Burlington, Massachusetts. On January 9, 2019, the Company held a Type C meeting with the Food and Drug Administration, or FDA, to discuss the dose delivery validation protocol. At the Type C meeting, the FDA informed the Company that the FDA did not agree that the Company’s proposed dose validation study was adequate, and an agreement was not reached during the Type C meeting. In January 2019, management implemented a restructuring plan to reduce operating costs and better align its workforce with the needs of its business. Under this restructuring plan, the Company reduced its workforce by approximately 43%, to 13 employees. The Company recorded a charge of $1.3 million during the three months ended March 31, 2019 related to the restructuring plan, which included severance, benefits and related costs. The Company recorded $852,000 and $426,000 in research and development expenses and general and administrative expenses related to the restructuring, respectively. The Company paid $341,000 of these costs during the three months ended March 31, 2019 and expects to pay $578,000 and $289,000 in the second and third quarters of 2019, respectively. The remainder of the restructuring charge consists of a non-cash charge of $70,000 related to the modification of stock options (Note 6). As of March 31, 2019, the Company had a balance of $867,000 in accrued expenses related to severance benefits, and related costs associated with the restructuring plan. Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”) for interim financial information and have been prepared on a basis which assumes that the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities and commitments in the normal course of business. The condensed consolidated financial statements reflect the operations of the Company and its wholly-owned subsidiary, scPharmaceuticals Securities Corporation. Certain information and disclosures normally included in financial statements in accordance with U.S. GAAP have been condensed or omitted. Accordingly, these condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements and related notes for the year ended December 31, 2018 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 21, 2019. The Company has determined that it operates in one segment. The accompanying condensed consolidated balance sheet as of March 31, 2019, the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2018 and 2019, the condensed consolidated statements of stockholders’ equity for the three months ended March 31, 2018 and 2019 and condensed consolidated statements of cash flows for the three months ended March 31, 2018 and 2019 are unaudited. The unaudited condensed consolidated financial statements have been prepared on a basis consistent with that used to prepare the Company’s audited annual financial statements and include, in the opinion of management, adjustments, consisting of normal recurring items, necessary for the fair statement of the condensed consolidated financial statements. The operating results for the three months ended March 31, 2019 are not necessarily indicative of the results expected for the full year ending December 31, 2019.

Significant Accounting Policies

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Significant Accounting Policies	2. Significant Accounting Policies Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reported periods. Actual results could differ from those estimates. Cash, Cash Equivalents and Restricted Cash Cash, cash equivalents and restricted cash consists of bank deposits, certificates of deposit and money market accounts with financial institutions. Cash equivalents are carried at cost which approximates fair value due to their short-term nature and which the Company believes do not have a material exposure to credit risk. The Company considers all highly liquid investments with maturities of three months or less from the date of purchase to be cash equivalents. The Company’s cash and cash equivalent accounts, at times, may exceed federally insured limits. The Company has not experienced any losses in such accounts. As of March 31, 2019, the Company classified $182,000 as restricted cash related to a letter of credit issued as a security deposit in connection with the Company’s lease of its corporate office facilities (Note 9). Cash, cash equivalents and restricted cash consists of the following: December 31, 2018 March 31, 2019 Cash and cash equivalents $ 89,478 $ 83,378 Restricted cash 182 182 Cash, cash equivalents and restricted cash $ 89,660 $ 83,560 Leases The Company determines if an arrangement is a lease at inception. Operating leases are included in right-of-use (“ROU”) lease assets, current portion of lease obligations, and long term lease obligations on the Company’s balance sheets. ROU lease assets represent the Company’s right to use an underlying asset for the lease term and lease obligations represent the Company’s obligation to make lease payments arising from the lease. Operating ROU lease assets and obligations are recognized at the commencement date based on the present value of lease payments over the lease term. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The ROU lease asset excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. Income Taxes The Company accounts for income taxes in accordance with the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) 740, Income Taxes. The Company provides reserves for potential payments of tax to various tax authorities related to uncertain tax positions. The tax benefits recorded are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is “more likely than not” to be realized following resolution of any uncertainty related to the tax benefit, assuming that the matter in question will be raised by the tax authorities. Potential interest and penalties associated with such uncertain tax positions are recorded as a component of income tax expense. At March 31, 2019, the Company had no such accruals. Recently Issued Accounting Standards In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) (“ASU 2018-13”). ASU 2018-13 modifies fair value disclosure requirements, specifically around level transfers and valuation of Level 3 assets and liabilities. ASU 2018-13 is effective for financial statements issued for annual and interim periods beginning after December 15, 2019 for all entities. Early adoption of all or part of ASU No. 2018-13 is permitted. The Company does not expect ASU 2018-13 to have a material impact on its financial statements.

Net Loss per Share

Net Loss per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Net Loss per Share	3. Net Loss per Share Net Loss per Share Attributable to Common Stockholders The following table sets forth the computation of basic and diluted net loss per share of common stock (in thousands, except share and per share data): Three Months Ended March 31, 2018 2019 Net loss and comprehensive loss $ (8,732 ) $ (8,719 ) Weighted-average shares used in computing net loss per share 18,535,432 18,575,726 Net loss per share, basic and diluted $ (0.47 ) $ (0.47 ) The Company’s potentially dilutive securities, which include stock options and convertible preferred stock, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect. Three Months Ended March 31, 2018 2019 Stock options to purchase common stock 1,748,617 1,409,325 Unvested restricted stock 122 160,900 Total 1,748,739 1,570,225

Property and Equipment

Property and Equipment	3 Months Ended
	Mar. 31, 2019
Property Plant And Equipment [Abstract]
Property and Equipment	4. Property and Equipment Purchased property and equipment consist of the following (dollars in thousands): ESTIMATED USEFUL LIFE December 31, 2018 March 31, 2019 Office equipment 5 years $ 10 $ 10 Office furniture 7 years 116 116 Computer equipment 3 years 8 8 Leasehold improvements Life of lease 95 95 229 229 Less: Accumulated depreciation (65 ) (75 ) Property and equipment, net $ 164 $ 154 Depreciation expense for the three months ended March 31, 2018 and March 31, 2019 was $10,000 and $10,000, respectively. Leased property and equipment consist of the following (dollars in thousands): ESTIMATED USEFUL LIFE December 31, 2018 March 31, 2019 Right-of-use lease assets - operating Lease term $ 2,024 $ 2,024 Less: Accumulated amortization (518 ) (597 ) Right-of-use lease assets - operating, net $ 1,506 $ 1,427 Amortization expense for the three months ended March 31, 2018 and March 31, 2019 was $71,000 and $79,000, respectively.

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2019
Accruals [Abstract]
Accrued Expenses	5. Accrued Expenses Accrued expenses consist of (in thousands): December 31, 2018 March 31, 2019 Contract research and development $ 1,492 $ 2,252 Unrecoverable component costs — 1,711 Severance costs 133 890 Employee compensation and related costs 727 327 Consulting and professional service fees 356 192 State taxes 165 54 Other 49 48 Total accrued expenses $ 2,922 $ 5,474

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	6. Stock-Based Compensation Stock Options The Company’s 2017 Stock Option and Incentive Plan (the “2017 Stock Plan”) became effective in November 2017, upon the closing of the Company’s initial public offering and will expire in October 2027. Under the 2017 Stock Plan, the Company may grant incentive stock options, non-statutory stock options, restricted stock awards, restricted stock units (“RSUs”) and other stock-based awards. The Company’s 2014 Stock Incentive Plan (the “2014 Stock Plan”) was terminated in November 2017 upon the completion of the Company’s initial public offering and no further options were granted under the 2014 Stock Plan. At March 31, 2019, there were 861,782 options outstanding under the 2014 Plan. As of March 31, 2019, there were 2,914,161 shares of the Company’s common stock authorized for issuance under the 2017 Stock Plan. At March 31, 2019, there were 2,436,605 options available for issuance under the 2017 Stock Plan and 547,543 options outstanding. Options granted under the 2017 Plan have a term of ten years. Vesting of options under the 2017 Stock Plan is determined by the board of directors, but is generally over one to four-year terms. The fair value of options at date of grant was estimated using the Black-Scholes option-pricing model with the following assumptions: Three Months Ended March 31, 2018 2019 Risk-free interest rate 2.42%-2.74% 2.51% Expected dividend yield 0% 0% Expected life 5.5-7.0 years 6.0 years Expected volatility 83%-86% 74% Weighted-average grant date fair value $ 9.44 $ 2.14 The following table summarizes information about stock option activity during the three months ended March 31, 2019 (in thousands, except share and per share data): NUMBER OF SHARES WEIGHTED- AVERAGE EXERCISE PRICE WEIGHTED- AVERAGE REMAINING CONTRACTUAL TERM AGGREGATE INTRINSIC VALUE Outstanding, December 31, 2018 1,588,306 $ 6.75 Granted 84,500 3.25 Exercised (11,141 ) 1.66 Forfeited (252,340 ) 8.55 Outstanding, March 31, 2019 1,409,325 $ 6.25 8.24 $ 40 Vested and exercisable, March 31, 2019 705,041 $ 6.30 7.71 $ 40 Vested and expected to vest, March 31, 2019 1,251,190 $ 6.32 8.14 $ 40 The following table summarizes information about RSU activity during the three months ended March 31, 2019: RSUs AVERAGE GRANT DATE FAIR VALUE (IN DOLLARS PER SHARE) Outstanding, December 31, 2018 — $ — Granted 160,900 1.43 Vested — — Forfeited — — RSUs outstanding at March 31, 2019 160,900 $ 1.43 Unrecognized compensation expense related to unvested options as of March 31, 2019 was $2.2 million and will be recognized over the remaining vesting periods of the underlying awards. The weighted-average period over which such compensation is expected to be recognized is 2.4 years. Unrecognized compensation expense related to unvested RSUs as of March 31, 2019 was $122,000 and will be recognized over the remaining vesting periods of the underlying awards. The weighted-average period over which such compensation is expected to be recognized is 2.1 years. During The Company recorded stock-based compensation expense in the following expense categories of its accompanying condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2018 and 2019 (in thousands): Three Months Ended March 31, 2018 2019 Research and development $ 186 $ 68 General and administrative 436 287 Total $ 622 $ 355

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	7. Fair Value of Financial Instruments The Financial Accounting Standards Board (“FASB”) Accounting Standard Codification (“ASC”) Topic, Fair Value Measurements and Disclosures (“ASC 820”), Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2—Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3—Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and observable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying values of the Company’s cash and restricted cash, prepaid expenses, value added tax, or VAT, receivable and deposits approximate their fair values due to their short-term nature. The carrying value of the Company’s loan payable was considered a reasonable estimate of fair value because the Company’s interest rate is near current market rates for instruments with similar characteristics. The Company’s cash equivalents are classified within Level 1 of the fair value hierarchy. The following table summarizes the Company’s money market funds as of March 31, 2019 (in thousands): TOTAL Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Cash equivalents: Cash equivalents $ 75,708 $ 75,708 $ — $ — Total cash equivalents $ 75,708 $ 75,708 $ — $ —

Term Loan

Term Loan	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Term Loan	8. Term Loan In May 2017, the Company entered into a loan and security agreement (the “2017 Loan Agreement”), with Solar Capital Ltd. and Silicon Valley Bank for $10.0 million. The 2017 Loan Agreement has a maturity date of May 1, 2021. Debt issuance costs for the 2017 Loan Agreement will be amortized to interest expense over the remaining term of the 2017 Loan Agreement using the effective-interest method. The interest rate under the 2017 Loan Agreement is LIBOR plus 8.45%. The initial interest-only period was until November 30, 2018, followed by a 30-month principal and interest period. The First Amendment to the Loan and Security Agreement, entered into in November 2018, extended the interest-only period, which currently runs through May 2019. If and when certain conditions are met, the interest-only period may be extended to August or November 2019. The rate at March 31, 2019 was 10.93188%. Pursuant to the 2017 Loan Agreement, the Company provided a first priority security interest in all existing and after-acquired assets, excluding intellectual property, owned by the Company. As of March 31, 2019, unpaid borrowings under the 2017 Loan Agreement totaled $10.0 million. For the three months ended March 31, 2019, the Company recorded $50,000 related to the amortization of debt discount associated with the 2017 Loan Agreement. For the three months ended March 31, 2018 the Company recorded $69,000 related to the amortization of debt discount associated with the 2017 Loan Agreement. The 2017 Loan Agreement allows the Company to voluntarily prepay all (but not less than all) of the outstanding principal at any time. A prepayment premium of 1% would be assessed on the outstanding principal. A final payment fee of $250,000 is due upon the earlier to occur of the maturity date or prepayment of such borrowings. The final payment fee was increased to $325,000 in the First Amendment to the 2017 Loan Agreement. For the three months ended March 31, 2019, the Company recorded $30,000 related to the amortization of the final payment fee associated with the 2017 Loan Agreement. For the three months ended March 31, 2018, the Company recorded $21,000 related to the amortization of the final payment fee associated with the 2017 Loan Agreement. In an event of default under the 2017 Loan Agreement, the interest rate will be increased by 5% and the balance under the loan may become immediately due and payable at the option of the lenders. The 2017 Loan Agreement includes restrictions on, among other things, the Company’s ability to incur additional indebtedness, change the name or location of the Company’s business, merge with or acquire other entities, pay dividends or make other distributions to holders of its capital stock, make certain investments, engage in transactions with affiliates, create liens, sell assets or pay subordinated debt. Total term loan and unamortized debt discount balances are as follows (in thousands): March 31, 2019 Face value $ 10,000 Less: discount (316 ) Total $ 9,684 Less: current portion (4,035 ) Total $ 5,649 As of March 31, 2019, future principal payments due under the 2017 Loan Agreement are as follows (in thousands): Year ended: December 31, 2019 $ 2,917 December 31, 2020 5,000 December 31, 2021 2,083 Total $ 10,000

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies Operating Leases The Company leases office facilities and equipment under long-term, non-cancelable operating lease agreements. The leases expire at various dates through 2022 and do not include renewal options. Certain leases provide for increases in future minimum annual rental payments as defined in the lease agreements. The leases generally also include real estate taxes and common area maintenance (“CAM”) charges in the annual rental payments. Pursuant to the terms of its lease agreement for the Company’s headquarters, the Company obtained a letter of credit in the amount of approximately $182,000 as security on the lease obligation. The letter of credit is listed as restricted cash on the Company’s consolidated balance sheets. Short-term leases are leases having a term of twelve months or less. The Company recognizes short-term leases on a straight-line basis and does not record a related lease asset or liability for such leases. The following is a maturity analysis of the annual undiscounted cash flows of the operating lease liabilities as of March 31, 2019 (in thousands): Year ended: December 31, 2019 $ 386 December 31, 2020 528 December 31, 2021 537 December 31, 2022 496 Total minimum lease payments 1,947 Less imputed interest (326 ) Total $ 1,621 Three Months Ended March 31, 2018 2019 Lease cost: Operating lease cost $ 119 $ 125 Short-term lease cost 2 2 Sublease income - (13 ) Total lease cost $ 121 $ 114 Other information Cash paid for amounts included in the measurement of lease liabilities $ 97 $ 127 Operating cash flows from operating leases $ 21 $ (6 ) Weighted-average remaining lease term - operating leases 4.7 years 3.7 years Weighted-average discount rate - operating leases 10.1 % 10.1 % In February 2018, the Company signed a sublease agreement for its facility located in Lexington, Massachusetts. The lease commenced on April 1, 2018 and has an initial term of three years with an extension term through December 2022. Contingencies The Company follows subtopic 450-20 of the FASB Accounting Standards Codification to report accounting for contingencies. Certain conditions may exist as of the date the financial statements are issued, which may result in a loss to the Company but which will only be resolved when one or more future events occur or fail to occur. The Company assesses such contingent liabilities, and such assessment inherently involves an exercise of judgment. If the assessment of a contingency indicates that it is probable that a material loss has been incurred and the amount of the liability can be estimated, then the estimated liability would be accrued in the Company’s financial statements. If the assessment indicates that a potential material loss contingency is not probable but is reasonably possible, or is probable but cannot be estimated, then the nature of the contingent liability, and an estimate of the range of possible losses, if determinable and material, would be disclosed. Loss contingencies considered remote are generally not disclosed unless they involve guarantees, in which case the guarantees would be disclosed. Due to the discontinuation of use of the sc2Wear Infusor, the Company has received notice of termination costs related to the program. The Company has accrued all costs for which it believes it is contractually liable. However, certain of the Company’s vendors have claimed or billed for additional costs for which the Company believes it is not obligated. At this time, the Company is not able to determine if it will incur any additional material costs as a result of such dispute. Depending on the timing and outcome of the dispute, and based on the Company’s position regarding the termination of the program, the Company currently estimates that additional termination costs, if any, could range from $0 to $3,000,000.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reported periods. Actual results could differ from those estimates.
Cash Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash Cash, cash equivalents and restricted cash consists of bank deposits, certificates of deposit and money market accounts with financial institutions. Cash equivalents are carried at cost which approximates fair value due to their short-term nature and which the Company believes do not have a material exposure to credit risk. The Company considers all highly liquid investments with maturities of three months or less from the date of purchase to be cash equivalents. The Company’s cash and cash equivalent accounts, at times, may exceed federally insured limits. The Company has not experienced any losses in such accounts. As of March 31, 2019, the Company classified $182,000 as restricted cash related to a letter of credit issued as a security deposit in connection with the Company’s lease of its corporate office facilities (Note 9). Cash, cash equivalents and restricted cash consists of the following: December 31, 2018 March 31, 2019 Cash and cash equivalents $ 89,478 $ 83,378 Restricted cash 182 182 Cash, cash equivalents and restricted cash $ 89,660 $ 83,560
Leases	Leases The Company determines if an arrangement is a lease at inception. Operating leases are included in right-of-use (“ROU”) lease assets, current portion of lease obligations, and long term lease obligations on the Company’s balance sheets. ROU lease assets represent the Company’s right to use an underlying asset for the lease term and lease obligations represent the Company’s obligation to make lease payments arising from the lease. Operating ROU lease assets and obligations are recognized at the commencement date based on the present value of lease payments over the lease term. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The ROU lease asset excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term.
Income Taxes	Income Taxes The Company accounts for income taxes in accordance with the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) 740, Income Taxes. The Company provides reserves for potential payments of tax to various tax authorities related to uncertain tax positions. The tax benefits recorded are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is “more likely than not” to be realized following resolution of any uncertainty related to the tax benefit, assuming that the matter in question will be raised by the tax authorities. Potential interest and penalties associated with such uncertain tax positions are recorded as a component of income tax expense. At March 31, 2019, the Company had no such accruals.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) (“ASU 2018-13”). ASU 2018-13 modifies fair value disclosure requirements, specifically around level transfers and valuation of Level 3 assets and liabilities. ASU 2018-13 is effective for financial statements issued for annual and interim periods beginning after December 15, 2019 for all entities. Early adoption of all or part of ASU No. 2018-13 is permitted. The Company does not expect ASU 2018-13 to have a material impact on its financial statements.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Schedule of Cash, Cash Equivalents and Restricted Cash	As of March 31, 2019, the Company classified $182,000 as restricted cash related to a letter of credit issued as a security deposit in connection with the Company’s lease of its corporate office facilities (Note 9). Cash, cash equivalents and restricted cash consists of the following: December 31, 2018 March 31, 2019 Cash and cash equivalents $ 89,478 $ 83,378 Restricted cash 182 182 Cash, cash equivalents and restricted cash $ 89,660 $ 83,560

Net Loss per Share (Tables)

Net Loss per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Loss Per Share of Common Stock	The following table sets forth the computation of basic and diluted net loss per share of common stock (in thousands, except share and per share data): Three Months Ended March 31, 2018 2019 Net loss and comprehensive loss $ (8,732 ) $ (8,719 ) Weighted-average shares used in computing net loss per share 18,535,432 18,575,726 Net loss per share, basic and diluted $ (0.47 ) $ (0.47 )
Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share	The Company’s potentially dilutive securities, which include stock options and convertible preferred stock, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect. Three Months Ended March 31, 2018 2019 Stock options to purchase common stock 1,748,617 1,409,325 Unvested restricted stock 122 160,900 Total 1,748,739 1,570,225

Property and Equipment (Tables)

Property and Equipment (Tables)	3 Months Ended
	Mar. 31, 2019
Property Plant And Equipment [Abstract]
Schedule of Purchased Property and Equipment	Purchased property and equipment consist of the following (dollars in thousands): ESTIMATED USEFUL LIFE December 31, 2018 March 31, 2019 Office equipment 5 years $ 10 $ 10 Office furniture 7 years 116 116 Computer equipment 3 years 8 8 Leasehold improvements Life of lease 95 95 229 229 Less: Accumulated depreciation (65 ) (75 ) Property and equipment, net $ 164 $ 154
Schedule of Leased Property and Equipment	Leased property and equipment consist of the following (dollars in thousands): ESTIMATED USEFUL LIFE December 31, 2018 March 31, 2019 Right-of-use lease assets - operating Lease term $ 2,024 $ 2,024 Less: Accumulated amortization (518 ) (597 ) Right-of-use lease assets - operating, net $ 1,506 $ 1,427

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2019
Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consist of (in thousands): December 31, 2018 March 31, 2019 Contract research and development $ 1,492 $ 2,252 Unrecoverable component costs — 1,711 Severance costs 133 890 Employee compensation and related costs 727 327 Consulting and professional service fees 356 192 State taxes 165 54 Other 49 48 Total accrued expenses $ 2,922 $ 5,474

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Estimated Fair Value of Options Valuation Assumptions	The fair value of options at date of grant was estimated using the Black-Scholes option-pricing model with the following assumptions: Three Months Ended March 31, 2018 2019 Risk-free interest rate 2.42%-2.74% 2.51% Expected dividend yield 0% 0% Expected life 5.5-7.0 years 6.0 years Expected volatility 83%-86% 74% Weighted-average grant date fair value $ 9.44 $ 2.14
Summary of Information about Stock Option Activity	The following table summarizes information about stock option activity during the three months ended March 31, 2019 (in thousands, except share and per share data): NUMBER OF SHARES WEIGHTED- AVERAGE EXERCISE PRICE WEIGHTED- AVERAGE REMAINING CONTRACTUAL TERM AGGREGATE INTRINSIC VALUE Outstanding, December 31, 2018 1,588,306 $ 6.75 Granted 84,500 3.25 Exercised (11,141 ) 1.66 Forfeited (252,340 ) 8.55 Outstanding, March 31, 2019 1,409,325 $ 6.25 8.24 $ 40 Vested and exercisable, March 31, 2019 705,041 $ 6.30 7.71 $ 40 Vested and expected to vest, March 31, 2019 1,251,190 $ 6.32 8.14 $ 40
Schedule of RSU Activity	The following table summarizes information about RSU activity during the three months ended March 31, 2019: RSUs AVERAGE GRANT DATE FAIR VALUE (IN DOLLARS PER SHARE) Outstanding, December 31, 2018 — $ — Granted 160,900 1.43 Vested — — Forfeited — — RSUs outstanding at March 31, 2019 160,900 $ 1.43
Summary of Stock-Based Compensation Expense	The Company recorded stock-based compensation expense in the following expense categories of its accompanying condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2018 and 2019 (in thousands): Three Months Ended March 31, 2018 2019 Research and development $ 186 $ 68 General and administrative 436 287 Total $ 622 $ 355

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Summary of Money Market Funds	The Company’s cash equivalents are classified within Level 1 of the fair value hierarchy. The following table summarizes the Company’s money market funds as of March 31, 2019 (in thousands): TOTAL Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Cash equivalents: Cash equivalents $ 75,708 $ 75,708 $ — $ — Total cash equivalents $ 75,708 $ 75,708 $ — $ —

Term Loan (Tables)

Term Loan (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Schedule of Total Term Loan and Unamortized Debt Discount	Total term loan and unamortized debt discount balances are as follows (in thousands): March 31, 2019 Face value $ 10,000 Less: discount (316 ) Total $ 9,684 Less: current portion (4,035 ) Total $ 5,649
Schedule of Future Principal Payments Due	As of March 31, 2019, future principal payments due under the 2017 Loan Agreement are as follows (in thousands): Year ended: December 31, 2019 $ 2,917 December 31, 2020 5,000 December 31, 2021 2,083 Total $ 10,000

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Schedule of Maturity Analysis of Annual Undiscounted Cash Flows of Operating Lease Liabilities	The following is a maturity analysis of the annual undiscounted cash flows of the operating lease liabilities as of March 31, 2019 (in thousands): Year ended: December 31, 2019 $ 386 December 31, 2020 528 December 31, 2021 537 December 31, 2022 496 Total minimum lease payments 1,947 Less imputed interest (326 ) Total $ 1,621
Schedule of Lease Cost and Other Information of Operating Lease Liabilities	Three Months Ended March 31, 2018 2019 Lease cost: Operating lease cost $ 119 $ 125 Short-term lease cost 2 2 Sublease income - (13 ) Total lease cost $ 121 $ 114 Other information Cash paid for amounts included in the measurement of lease liabilities $ 97 $ 127 Operating cash flows from operating leases $ 21 $ (6 ) Weighted-average remaining lease term - operating leases 4.7 years 3.7 years Weighted-average discount rate - operating leases 10.1 % 10.1 %

Description of Business and B_2

Description of Business and Basis of Presentation - Additional Information (Details)	1 Months Ended	3 Months Ended
	Jan. 31, 2019Employee	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Restructuring charges				$ 1,300,000
Approximate percentage of workforce reductions	43.00%
Number of positions remaining | Employee	13
Restructuring cost paid				341,000
Non-cash charge related to modification of stock options				70,000
Severance, benefits, and related costs				867,000
Scenario, Forecast
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Restructuring cost paid		$ 289,000	$ 578,000
Research and Development
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Restructuring charges				852,000
General and Administrative
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Restructuring charges				$ 426,000

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Schedule Of Accounting Policies [Line Items]
Restricted cash	$ 182,000	$ 182,000
Potential interest and penalties associated with uncertain tax positions, accruals	0
Letter of Credit
Schedule Of Accounting Policies [Line Items]
Restricted cash	$ 182,000

Significant Accounting Polici_5

Significant Accounting Policies - Schedule of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 83,378	$ 89,478
Restricted cash	182	182
Cash, cash equivalents and restricted cash	$ 83,560	$ 89,660	$ 109,462	$ 118,480

Net Loss per Share - Computatio

Net Loss per Share - Computation of Basic and Diluted Net Loss Per Share of Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net loss and comprehensive loss	$ (8,719)	$ (8,732)
Weighted-average shares used in computing net loss per share	18,575,726	18,535,432
Net loss per share, basic and diluted	$ (0.47)	$ (0.47)

Net Loss per Share - Schedule o

Net Loss per Share - Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	1,570,225	1,748,739
Stock Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	1,409,325	1,748,617
Unvested Restricted Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	160,900	122

Property and Equipment - Schedu

Property and Equipment - Schedule of Purchased Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
ESTIMATED USEFUL LIFE	Lease term
Property and equipment, gross	$ 229	$ 229
Less: Accumulated depreciation	(75)	(65)
Property and equipment, net	$ 154	164
Office Equipment
Property Plant And Equipment [Line Items]
ESTIMATED USEFUL LIFE	5 years
Property and equipment, gross	$ 10	10
Office Furniture
Property Plant And Equipment [Line Items]
ESTIMATED USEFUL LIFE	7 years
Property and equipment, gross	$ 116	116
Computer Equipment
Property Plant And Equipment [Line Items]
ESTIMATED USEFUL LIFE	3 years
Property and equipment, gross	$ 8	8
Leasehold Improvements
Property Plant And Equipment [Line Items]
ESTIMATED USEFUL LIFE	Life of lease
Property and equipment, gross	$ 95	$ 95

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Property Plant And Equipment [Abstract]
Depreciation expense	$ 10,000	$ 10,000
Amortization expense	$ 79,000	$ 71,000

Property and Equipment - Sche_2

Property and Equipment - Schedule of Leased Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Right-of-use lease assets - operating	$ 2,024	$ 2,024
Less: Accumulated amortization	(597)	(518)
Right-of-use lease assets - operating, net	$ 1,427	$ 1,506
ESTIMATED USEFUL LIFE	Lease term

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accruals [Abstract]
Contract research and development	$ 2,252	$ 1,492
Unrecoverable component costs	1,711
Severance costs	890	133
Employee compensation and related costs	327	727
Consulting and professional service fees	192	356
State taxes	54	165
Other	48	49
Total accrued expenses	$ 5,474	$ 2,922

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional options granted	84,500
Stock option, number of shares outstanding	1,409,325	1,588,306
Unrecognized compensation expense	$ 2,200,000
Recognition period (in years)	2 years 4 months 24 days
Weighted average exercise price for vested options	$ 8.30
Incremental stock-based compensation expense	$ 70,000
Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option vesting term	1 year
Number of options vested	51,673
Tranche Two
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option vesting term	2 years
Number of options vested	85,432
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense	$ 122,000
Recognition period (in years)	2 years 1 month 6 days
2017 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option and incentive plan effective date	Nov. 30, 2017
Stock option and incentive plan expiration date	Oct. 31, 2027
Stock option, number of shares outstanding	547,543
Number of common shares authorized for issuance	2,914,161
Stock options, available for issuance	2,436,605
Term of option granted	10 years
2017 Stock Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option vesting term	1 year
2017 Stock Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option vesting term	4 years
2014 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option and incentive plan expiration date	Nov. 30, 2017
Additional options granted	0
Stock option, number of shares outstanding	861,782

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Estimated Fair Value of Options Valuation Assumptions (Details) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	2.51%
Risk-free interest rate, minimum		2.42%
Risk-free interest rate, maximum		2.74%
Expected dividend yield	0.00%	0.00%
Expected life	6 years
Expected volatility	74.00%
Expected volatility, minimum		83.00%
Expected volatility, maximum		86.00%
Weighted-average grant date fair value	$ 2.14	$ 9.44
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life		5 years 6 months
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life		7 years

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Information about Stock Option Activity (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)$ / sharesshares
NUMBER OF SHARES
Number of shares outstanding, beginning balance | shares	1,588,306
Additional options granted | shares	84,500
Number of shares exercised | shares	(11,141)
Number of shares forfeited | shares	(252,340)
Number of shares outstanding, ending balance | shares	1,409,325
Vested and exercisable, ending balance | shares	705,041
Vested and expected to vest, ending balance | shares	1,251,190
WEIGHTED-AVERAGE EXERCISE PRICE
Weighted average exercise prices, outstanding beginning balance | $ / shares	$ 6.75
Weighted average exercise prices, granted | $ / shares	3.25
Weighted average exercise prices, exercised | $ / shares	1.66
Weighted average exercise prices, forfeited | $ / shares	8.55
Weighted average exercise prices, outstanding ending balance | $ / shares	6.25
Weighted average exercise prices, vested and exercisable ending balance | $ / shares	6.30
Weighted average exercise prices, vested and expected to vest ending balance | $ / shares	$ 6.32
WEIGHTED-AVERAGE REMAINING CONTRACTUAL TERM
Weighted average remaining contractual term, outstanding	8 years 2 months 26 days
Weighted average remaining contractual term, vested and exercisable	7 years 8 months 15 days
Weighted average remaining contractual term, vested and expected to vest	8 years 1 month 20 days
AGGREGATE INTRINSIC VALUE
Aggregate intrinsic value, outstanding ending balance | $	$ 40
Aggregate intrinsic value, vested and exercisable ending balance | $	40
Aggregate intrinsic value, vested and expected to vest ending balance | $	$ 40

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of RSU Activity (Details) - Restricted Stock Units (RSUs)	3 Months Ended
	Mar. 31, 2019$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs Outstanding, December 31, 2018 | shares	0
RSUs Granted | shares	160,900
RSUs outstanding at March 31, 2019 | shares	160,900
AVERAGE GRANT DATE FAIR VALUE, Outstanding, December 31, 2018 | $ / shares	$ 0
AVERAGE GRANT DATE FAIR VALUE, Granted | $ / shares	1.43
AVERAGE GRANT DATE FAIR VALUE, RSUs outstanding at March 31, 2019 | $ / shares	$ 1.43

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 355	$ 622
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	68	186
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 287	$ 436

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Summary of Money Market Funds (Details) - Fair Value, Measurements, Nonrecurring $ in Thousands	Mar. 31, 2019USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Cash equivalents	$ 75,708
Quoted Prices in Active Markets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Cash equivalents	75,708
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Cash equivalents	75,708
Money Market Funds | Quoted Prices in Active Markets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Cash equivalents	$ 75,708

Term Loan - Additional Informat

Term Loan - Additional Information (Details) - Solar Capital Ltd. and Silicon Valley Bank - USD ($)	1 Months Ended		3 Months Ended
	Nov. 30, 2018	May 31, 2017	Mar. 31, 2019	Mar. 31, 2018
2017 Loan Agreement
Debt Instrument [Line Items]
Loan and security agreement, amount		$ 10,000,000
Loan agreement, maturity date		May 1, 2021
Unpaid borrowings			$ 10,000,000
Amortization of debt discount			$ 50,000	$ 69,000
Prepayment premium thereafter			1.00%
Final payment fee			$ 250,000
Amortization of final payment fee			$ 30,000	$ 21,000
Increase in interest rate on default			5.00%
2017 Loan Agreement | Libor
Debt Instrument [Line Items]
Basis spread on variable base rate		8.45%
First Amendment to Loan and Security Agreement
Debt Instrument [Line Items]
Basis spread on variable base rate			10.93188%
Final payment fee	$ 325,000

Term Loan - Schedule of Total T

Term Loan - Schedule of Total Term Loan and Unamortized Debt Discount (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Less: current portion	$ (4,035)	$ (2,811)
Term loan, long term	5,649	$ 6,826
2017 Loan Agreement | Solar Capital Ltd. and Silicon Valley Bank
Debt Instrument [Line Items]
Face value	10,000
Less: discount	(316)
Total	9,684
Less: current portion	(4,035)
Term loan, long term	$ 5,649

Term Loan - Schedule of Future

Term Loan - Schedule of Future Principal Payments Due (Details) - 2017 Loan Agreement - Solar Capital Ltd. and Silicon Valley Bank $ in Thousands	Mar. 31, 2019USD ($)
Debt Instrument [Line Items]
December 31, 2019	$ 2,917
December 31, 2020	5,000
December 31, 2021	2,083
Total	$ 10,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended
	Feb. 28, 2018	Mar. 31, 2019	Dec. 31, 2018
Commitments And Contingencies [Line Items]
Operating leases expire		2022
Restricted cash		$ 182,000	$ 182,000
Short-term lease asset		1,427,000	1,506,000
Short-term lease liability		366,000	$ 353,000
Operating sublease term	3 years
Minimum
Commitments And Contingencies [Line Items]
Estimated additional termination costs		0
Maximum
Commitments And Contingencies [Line Items]
Estimated additional termination costs		3,000,000
Short-term Leases Recognized on Straight-line Basis
Commitments And Contingencies [Line Items]
Short-term lease asset		0
Short-term lease liability		0
Letter of Credit
Commitments And Contingencies [Line Items]
Restricted cash		182,000
Letter of Credit | Lease Agreement Require Standby Letter of Credit
Commitments And Contingencies [Line Items]
Restricted cash		$ 182,000

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Maturity Analysis of Annual Undiscounted Cash Flows of Operating Lease Liabilities (Details) $ in Thousands	Mar. 31, 2019USD ($)
Year ended:
December 31, 2019	$ 386
December 31, 2020	528
December 31, 2021	537
December 31, 2022	496
Total minimum lease payments	1,947
Less imputed interest	(326)
Total	$ 1,621

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Lease Cost and Other Information of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Lease cost:
Operating lease cost	$ 125	$ 119
Short-term lease cost	2	2
Sublease income	(13)
Total lease cost	114	121
Other information
Cash paid for amounts included in the measurement of lease liabilities	127	97
Operating cash flows from operating leases	$ (6)	$ 21
Weighted-average remaining lease term - operating leases	3 years 8 months 12 days	4 years 8 months 12 days
Weighted-average discount rate - operating leases	10.10%	10.10%