scPharmaceuticals (SCPH) 10-Q 12 May 20 2020 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	May 08, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
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 Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common stock, par value $0.0001
Security Exchange Name	NASDAQ
Entity File Number	001-38293
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-5184075
Entity Address, Address Line One	2400 District Avenue
Entity Address, Address Line Two	Suite 310
Entity Address, City or Town	Burlington
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01803
City Area Code	617
Local Phone Number	517-0730
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		21,010,437

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 75,339	$ 72,624
Prepaid expenses	3,370	2,619
VAT receivable	305	310
Other current assets	59	94
Total current assets	79,073	75,647
Restricted cash	182	182
Property and equipment, net	119	127
Right-of-use lease assets - operating, net	1,092	1,179
Deposits and other assets	22	148
Total assets	80,488	77,283
Current liabilities
Accounts payable	652	1,142
Accrued expenses	3,590	3,688
Current portion of lease obligation - operating	421	407
Total current liabilities	4,663	5,237
Term loan, long term	18,996	18,915
Long term lease obligation - operating	832	943
Derivative liability	795	765
Other liabilities	98	58
Total liabilities	25,384	25,918
Commitments and contingencies (Note 10)
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, 2020; 19,418,955 and 20,981,880 shares issued and outstanding as of December 31, 2019 and March 31, 2020, respectively	2	2
Additional paid-in capital	191,649	180,818
Accumulated deficit	(136,547)	(129,455)
Total stockholders’ equity	55,104	51,365
Total liabilities and stockholders’ equity	$ 80,488	$ 77,283

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
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	20,981,880	19,418,955
Common stock, shares outstanding	20,981,880	19,418,955

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating expenses:
Research and development	$ 4,146	$ 6,524
General and administrative	2,503	2,323
Total operating expenses	6,649	8,847
Loss from operations	(6,649)	(8,847)
Other expense	(31)	(8)
Interest income	224	490
Interest expense	(636)	(354)
Net loss and comprehensive loss	$ (7,092)	$ (8,719)
Net loss per share — basic and diluted	$ (0.35)	$ (0.47)
Weighted average common shares outstanding — basic and diluted	20,218,473	18,575,726

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	At The Market Offering	Common Stock	Common StockAt The Market Offering	Additional Paid-in Capital	Additional Paid-in CapitalAt The Market Offering	Accumulated Deficit
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
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
Beginning Balance at Dec. 31, 2019	51,365		$ 2		180,818		(129,455)
Beginning Balance, Shares at Dec. 31, 2019			19,418,955
Net loss	(7,092)						(7,092)
Issuance of common stock under at-the-market offering, net of commissions and issuance costs		$ 10,253				$ 10,253
Issuance of common stock under at-the-market offering, net of commissions and issuance costs, Shares				1,502,892
Issuance of common stock upon exercise of stock options	$ 154				154
Issuance of common stock upon exercise of stock options, Shares	30,143		30,143
Vesting of restricted stock units, net of tax withholdings	$ (84)				(84)
Vesting of restricted stock units, net of tax withholdings, Shares			29,890
Stock-based compensation	508				508
Ending Balance at Mar. 31, 2020	$ 55,104		$ 2		$ 191,649		$ (136,547)
Ending Balance, Shares at Mar. 31, 2020			20,981,880

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities
Net loss	$ (7,092,000)	$ (8,719,000)
Adjustments to reconcile net loss to cash used in operating activities
Depreciation expense	8,000	10,000
Amortization expense - right-of-use leased assets - operating	87,000	79,000
Stock-based compensation	508,000	355,000
Non-cash interest expense	121,000	80,000
Fair value adjustment to derivative liability	30,000
Changes in operating assets and liabilities
Prepaid expenses and other assets	(720,000)	(19,000)
Accounts payable, accrued expenses and other liabilities	(685,000)	2,096,000
Net cash used in operating activities	(7,743,000)	(6,118,000)
Cash flows from financing activities
Proceeds from at-the-market offering, net	10,388,000
Proceeds from the exercise of vested stock options	154,000	18,000
Settlements of restricted stock units for tax withholding obligations	(84,000)
Net cash provided by financing activities	10,458,000	18,000
Net (decrease) increase in cash, cash equivalents and restricted cash	2,715,000	(6,100,000)
Cash, cash equivalents and restricted cash at beginning of period	72,806,000	89,660,000
Cash, cash equivalents and restricted cash at end of period	75,521,000	83,560,000
Supplemental cash flow information
Interest paid	518,000	274,000
Taxes paid		$ 166,000
Supplemental disclosure of non-cash activities
Transfer of issuance costs from other noncurrent assets to equity	$ 135,000

Description of Business and Bas

Description of Business and Basis of Presentation	3 Months Ended
	Mar. 31, 2020
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 optimize the delivery of infused therapies, advance patient care and reduce healthcare costs. The Company’s strategy is designed to enable the subcutaneous administration of therapies that have previously been limited to intravenous (“IV”) delivery. The Company’s headquarters and primary place of business is Burlington, Massachusetts. 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, 2019 included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (the”SEC”) on March 24, 2020. The Company has determined that it operates in one segment. The accompanying condensed consolidated balance sheet as of March 31, 2020, the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2019 and 2020, the condensed consolidated statements of stockholders’ equity for the three months ended March 31, 2019 and 2020 and condensed consolidated statements of cash flows for the three months ended March 31, 2019 and 2020 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, 2020 are not necessarily indicative of the results expected for the full year ending December 31, 2020.

Significant Accounting Policies

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2020
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, 2020, 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 10). Cash, cash equivalents and restricted cash consists of the following (in thousands): December 31, 2019 March 31, 2020 Cash and cash equivalents $ 72,624 $ 75,339 Restricted cash 182 182 Cash, cash equivalents and restricted cash $ 72,806 $ 75,521 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, 2020, 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. The Company adopted ASU 2018-13 on January 1, 2020 and there has not been any impact to its financial statements.

Net Loss per Share

Net Loss per Share	3 Months Ended
	Mar. 31, 2020
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, 2019 2020 Net loss and comprehensive loss $ (8,719 ) $ (7,092 ) Weighted-average shares used in computing net loss per share 18,575,726 20,218,473 Net loss per share, basic and diluted $ (0.47 ) $ (0.35 ) The Company’s potentially dilutive securities, which include stock options and unvested restricted stock units, 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, 2019 2020 Stock options to purchase common stock 1,409,325 2,058,355 Unvested restricted stock units 160,900 122,700 Total 1,570,225 2,181,055

Property and Equipment

Property and Equipment	3 Months Ended
	Mar. 31, 2020
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, 2019 March 31, 2020 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 (102 ) (110 ) Property and equipment, net $ 127 $ 119 Depreciation expense for the three months ended March 31, 2019 and March 31, 2020 was $10,000 and $8,000, respectively.

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2020
Accruals [Abstract]
Accrued Expenses	5. Accrued Expenses Accrued expenses consist of the following (in thousands): December 31, 2019 March 31, 2020 Contract research and development $ 2,001 $ 2,322 Employee compensation and related costs 1,250 798 Consulting and professional service fees 296 321 Interest 91 88 State taxes 49 61 Other 1 - Total accrued expenses $ 3,688 $ 3,590

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2020
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, 2020, there were 786,323 options outstanding under the 2014 Stock Plan. As of March 31, 2020, there were 3,926,232 shares of the Company’s common stock authorized for issuance under the 2017 Stock Plan, including 265,203 options that had been forfeited from the 2014 Stock Plan. At March 31, 2020, there were 2,523,190 options available for issuance under the 2017 Stock Plan, 1,272,032 options outstanding and 122,700 RSUs outstanding. Awards granted under the 2017 Stock Plan have a term of ten years. Vesting of awards 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, 2019 2020 Risk-free interest rate 2.51% 0.93%-1.71% Expected dividend yield 0% 0% Expected life 6.0 years 5.5-6.6 years Expected volatility 74% 72%-73% Weighted-average grant date fair value $ 2.14 $ 3.91 The following table summarizes information about stock option activity during the three months ended March 31, 2020: (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, 2019 1,439,518 $ 6.09 Granted 684,310 6.07 Exercised (30,143 ) 5.11 Forfeited (35,330 ) 11.97 Outstanding, March 31, 2020 2,058,355 $ 6.00 8.19 $ 4,366 Vested and exercisable, March 31, 2020 905,428 $ 6.01 7.01 $ 2,109 Vested and expected to vest, March 31, 2020 1,663,171 $ 5.99 7.87 $ 3,702 Of the options granted in the three months ended March 31, 2020, 226,110 were performance-based options. Vesting of these performance-based options is contingent on the occurrence of certain regulatory and commercial milestones. The Company is recognizing the expense as straight-line over the expected performance achievement term. The following table summarizes information about RSU activity during the three months ended March 31, 2020: RSUs AVERAGE GRANT DATE FAIR VALUE (IN DOLLARS PER SHARE) RSUs Outstanding, December 31, 2019 160,900 $ 3.25 Granted — — Vested (38,200 ) 3.25 Forfeited — — RSUs outstanding at March 31, 2020 122,700 $ 3.25 The number of RSUs vested includes shares of common stock withheld on behalf of employees to satisfy the minimum statutory tax withholding requirements. Unrecognized compensation expense related to unvested options as of March 31, 2020 was $2.7 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 2.1 years. Unrecognized compensation expense related to unvested RSUs as of March 31, 2020 was $208,000 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 0.8 years. 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, 2019 and 2020 (in thousands): Three Months Ended March 31, 2019 2020 Research and development $ 68 $ 144 General and administrative 287 364 Total $ 355 $ 508

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2020
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 following table summarizes the Company’s assets and liabilities as of March 31, 2020 that are measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values (in thousands): TOTAL Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 75,070 $ 75,070 $ — $ — Total $ 75,070 $ 75,070 $ — $ — Liabilities: Derivative liability $ 795 $ — $ — $ 795 Total $ 795 $ — $ — $ 795 The fair value of the derivative liability recognized in connection with the Company’s 2019 Loan Agreement (Note 8) was determined based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The fair value of the derivative liability was determined using the probability-weighted expected return method, which considered as inputs the timing and probability of occurrence of an exit event, the amount of the payment, and the risk-free discount rate reflecting the expected risk profile for each of the potential settlement scenarios.

Term Loan

Term Loan	3 Months Ended
	Mar. 31, 2020
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, (together, the “Lenders”) for $10.0 million. The 2017 Loan Agreement had a maturity date of May 1, 2021. Debt issuance costs for the 2017 Loan Agreement were to 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 was 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 through May 2019. The Third Amendment to the Loan and Security Agreement, entered into in May 2019, extended the interest-only period through August 2019, with the ability to further extend the interest only period to November 2019. 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. 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. The 2017 Loan Agreement allowed 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 was 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. In September 2019, the Company replaced the 2017 Loan Agreement with a new $20.0 million term loan with the Lenders, the 2019 Loan Agreement. The restructured four-year term loan facility allows for an expansion of the 2017 Loan Agreement. Some of the proceeds from the 2019 Loan Agreement were used to pay off the 2017 Loan Agreement including the final fee of $325,000. The 2019 Loan Agreement extends the term of the credit facility until September 17, 2023. The payoff of the 2017 Loan Agreement was treated as a modification of the debt. Debt issuance costs for the 2019 Loan Agreement, including unamortized issuance costs for the 2017 Loan Agreement, will be amortized to interest expense over the remaining term of the 2019 Loan Agreement using the effective-interest method. The interest rate under the 2019 Loan Agreement is the higher of (i) LIBOR plus 7.95% or (ii) 10.18% and there is an interest-only period until September 30, 2021. The rate at March 31, 2020 was 10.18%. Pursuant to the 2019 Loan Agreement, the Company provided a first priority security interest in substantially all of the Company’s assets, including intellectual property, subject to certain exceptions. The Company entered into the Exit Agreement in connection with the 2019 Loan Agreement which provides for an aggregate payment of 4% of the loan commitment, or $800,000, to the lenders upon the occurrence of an exit event. The Company concluded that the exit payment obligation met the definition of a derivative that was required to be accounted for as a separate unit of accounting. The Company recorded the issuance-date fair value of the derivative liability of $763,000 as a debt discount and as a derivative liability in the Company’s balance sheet. The derivative liability is re-measured at each balance sheet date and any changes in estimated fair value is recorded as other income (expense). For the three months ended March 31, 2020, the Company recorded $30,000 in non-cash expense as a fair value adjustment to the derivative liability. As of March 31, 2020, unpaid borrowings under the 2019 Loan Agreement totaled $20.0 million. For the three months ended March 31, 2020, the Company recorded $81,000 related to the amortization of debt discount associated with the 2019 Loan Agreement. The 2019 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 3% or 1% through the one-year anniversary and the two-year anniversary, respectively, would be assessed on the outstanding principal. After the two-year anniversary, a 0.5% prepayment premium would be assessed on the outstanding principal. A final payment fee of $500,000 is due upon the earlier to occur of the maturity date or prepayment of such borrowings. For the three months ended March 31, 2020, the Company recorded $40,000 related to the amortization of the final payment fee associated with the 2019 Loan Agreement. In an event of default under the 2019 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 2019 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, 2020 Face value $ 20,000 Less: discount (1,004 ) Total $ 18,996 Less: current portion - Long-term portion $ 18,996 As of March 31, 2020, future principal payments due under the 2019 Loan Agreement are as follows (in thousands): Year ended: December 31, 2021 $ 2,500 December 31, 2022 10,000 December 31, 2023 7,500 Total minimum principal payments $ 20,000

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Stockholders' Equity	9. Stockholders’ Equity At-the-Market Issuance Sales Agreement On August 23, 2019, the Company entered into an Open Market Sale Agreement SM Subject to the terms and conditions of the ATM Agreement, Jefferies used its commercially reasonable efforts to sell the ATM Shares, based upon instructions from the Company, consistent with its normal trading and sales practices. The Company paid Jefferies a commission equal to 3.0% of the gross sales proceeds of such ATM Shares. During the three months ended March 31, 2020, the Company sold a total of 1,502,892 ATM Shares under the ATM Agreement, in the open market, at a weighted average gross selling price of $7.13 per share for net proceeds of $10.4 million, which completed the ATM program. The Company incurred $189,000 of legal, accounting and other costs to establish and activate the ATM program. During the three months ended March 31, 2020, the Company charged the remaining $135,000 of these costs against additional paid in capital upon issuance of shares.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	10 . 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 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, 2020 (in thousands): Year ended: December 31, 2020 $ 397 December 31, 2021 537 December 31, 2022 496 Total minimum lease payments 1,430 Less imputed interest (177 ) Total $ 1,253 Three Months Ended March 31, 2019 2020 Lease cost: Operating lease cost $ 125 $ 122 Short-term lease cost 2 - Sublease income (13 ) (12 ) Total lease cost $ 114 $ 110 Other information Cash paid for amounts included in the measurement of lease liabilities $ 127 $ 173 Operating cash flows from operating leases $ (6 ) $ (10 ) Weighted-average remaining lease term - operating leases 3.7 years 2.7 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 sublease commenced on April 1, 2018 and had an initial term of three years with an extension term through December 2022. In February 2020, the sublease was extended until December 31, 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 Company’s first generation product candidate, sc2Wear Infusor, the Company has received notice of termination costs from vendors related to the program. The Company has accrued all costs for which it either believes it is contractually liable or for which the Company has negotiated settlement agreements in good faith. 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 estimates that additional termination costs, if any, will be immaterial to the Company’s financial statements.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2020
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, 2020, 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 10). Cash, cash equivalents and restricted cash consists of the following (in thousands): December 31, 2019 March 31, 2020 Cash and cash equivalents $ 72,624 $ 75,339 Restricted cash 182 182 Cash, cash equivalents and restricted cash $ 72,806 $ 75,521
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, 2020, 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. The Company adopted ASU 2018-13 on January 1, 2020 and there has not been any impact to its financial statements.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Schedule of Cash, Cash Equivalents and Restricted Cash	As of March 31, 2020, 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 10). Cash, cash equivalents and restricted cash consists of the following (in thousands): December 31, 2019 March 31, 2020 Cash and cash equivalents $ 72,624 $ 75,339 Restricted cash 182 182 Cash, cash equivalents and restricted cash $ 72,806 $ 75,521

Net Loss per Share (Tables)

Net Loss per Share (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2019 2020 Net loss and comprehensive loss $ (8,719 ) $ (7,092 ) Weighted-average shares used in computing net loss per share 18,575,726 20,218,473 Net loss per share, basic and diluted $ (0.47 ) $ (0.35 )
Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share	The Company’s potentially dilutive securities, which include stock options and unvested restricted stock units, 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, 2019 2020 Stock options to purchase common stock 1,409,325 2,058,355 Unvested restricted stock units 160,900 122,700 Total 1,570,225 2,181,055

Property and Equipment (Tables)

Property and Equipment (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2019 March 31, 2020 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 (102 ) (110 ) Property and equipment, net $ 127 $ 119

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2020
Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consist of the following (in thousands): December 31, 2019 March 31, 2020 Contract research and development $ 2,001 $ 2,322 Employee compensation and related costs 1,250 798 Consulting and professional service fees 296 321 Interest 91 88 State taxes 49 61 Other 1 - Total accrued expenses $ 3,688 $ 3,590

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2019 2020 Risk-free interest rate 2.51% 0.93%-1.71% Expected dividend yield 0% 0% Expected life 6.0 years 5.5-6.6 years Expected volatility 74% 72%-73% Weighted-average grant date fair value $ 2.14 $ 3.91
Summary of Information about Stock Option Activity	The following table summarizes information about stock option activity during the three months ended March 31, 2020: (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, 2019 1,439,518 $ 6.09 Granted 684,310 6.07 Exercised (30,143 ) 5.11 Forfeited (35,330 ) 11.97 Outstanding, March 31, 2020 2,058,355 $ 6.00 8.19 $ 4,366 Vested and exercisable, March 31, 2020 905,428 $ 6.01 7.01 $ 2,109 Vested and expected to vest, March 31, 2020 1,663,171 $ 5.99 7.87 $ 3,702
Schedule of RSU Activity	The following table summarizes information about RSU activity during the three months ended March 31, 2020: RSUs AVERAGE GRANT DATE FAIR VALUE (IN DOLLARS PER SHARE) RSUs Outstanding, December 31, 2019 160,900 $ 3.25 Granted — — Vested (38,200 ) 3.25 Forfeited — — RSUs outstanding at March 31, 2020 122,700 $ 3.25
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, 2019 and 2020 (in thousands): Three Months Ended March 31, 2019 2020 Research and development $ 68 $ 144 General and administrative 287 364 Total $ 355 $ 508

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table summarizes the Company’s assets and liabilities as of March 31, 2020 that are measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values (in thousands): TOTAL Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 75,070 $ 75,070 $ — $ — Total $ 75,070 $ 75,070 $ — $ — Liabilities: Derivative liability $ 795 $ — $ — $ 795 Total $ 795 $ — $ — $ 795

Term Loan (Tables)

Term Loan (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 Face value $ 20,000 Less: discount (1,004 ) Total $ 18,996 Less: current portion - Long-term portion $ 18,996
Schedule of Future Principal Payments Due	As of March 31, 2020, future principal payments due under the 2019 Loan Agreement are as follows (in thousands): Year ended: December 31, 2021 $ 2,500 December 31, 2022 10,000 December 31, 2023 7,500 Total minimum principal payments $ 20,000

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 (in thousands): Year ended: December 31, 2020 $ 397 December 31, 2021 537 December 31, 2022 496 Total minimum lease payments 1,430 Less imputed interest (177 ) Total $ 1,253
Schedule of Lease Cost and Other Information of Operating Lease Liabilities	Three Months Ended March 31, 2019 2020 Lease cost: Operating lease cost $ 125 $ 122 Short-term lease cost 2 - Sublease income (13 ) (12 ) Total lease cost $ 114 $ 110 Other information Cash paid for amounts included in the measurement of lease liabilities $ 127 $ 173 Operating cash flows from operating leases $ (6 ) $ (10 ) Weighted-average remaining lease term - operating leases 3.7 years 2.7 years Weighted-average discount rate - operating leases 10.1 % 10.1 %

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
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, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 75,339	$ 72,624
Restricted cash	182	182
Cash, cash equivalents and restricted cash	$ 75,521	$ 72,806	$ 83,560	$ 89,660

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, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net loss and comprehensive loss	$ (7,092)	$ (8,719)
Weighted-average shares used in computing net loss per share	20,218,473	18,575,726
Net loss per share, basic and diluted	$ (0.35)	$ (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, 2020	Mar. 31, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	2,181,055	1,570,225
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	2,058,355	1,409,325
Unvested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	122,700	160,900

Property and Equipment - Schedu

Property and Equipment - Schedule of Purchased Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 229	$ 229
Less: Accumulated depreciation	(110)	(102)
Property and equipment, net	$ 119	127
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, 2020	Mar. 31, 2019
Property Plant And Equipment [Abstract]
Depreciation expense	$ 8,000	$ 10,000

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accruals [Abstract]
Contract research and development	$ 2,322	$ 2,001
Employee compensation and related costs	798	1,250
Consulting and professional service fees	321	296
Interest	88	91
State taxes	61	49
Other		1
Total accrued expenses	$ 3,590	$ 3,688

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional options granted	684,310
Stock option, number of shares outstanding	2,058,355	1,439,518
Unrecognized compensation expense	$ 2,700,000
Recognition period (in years)	2 years 1 month 6 days
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense	$ 208,000
Recognition period (in years)	9 months 18 days
Performance Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional options granted	226,110
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	1,272,032
Number of common shares authorized for issuance	3,926,232
Stock options, available for issuance	2,523,190
Term of option granted	10 years
2017 Stock Plan | Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of restricted stock units outstanding	122,700
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	786,323
Number of options forfeited	265,203

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Estimated Fair Value of Options Valuation Assumptions (Details) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate		2.51%
Risk-free interest rate, minimum	0.93%
Risk-free interest rate, maximum	1.71%
Expected dividend yield	0.00%	0.00%
Expected life		6 years
Expected volatility		74.00%
Expected volatility, minimum	72.00%
Expected volatility, maximum	73.00%
Weighted-average grant date fair value	$ 3.91	$ 2.14
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	6 years 7 months 6 days

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, 2020USD ($)$ / sharesshares
NUMBER OF SHARES
Number of shares outstanding, beginning balance | shares	1,439,518
Additional options granted | shares	684,310
Number of shares exercised | shares	(30,143)
Number of shares forfeited | shares	(35,330)
Number of shares outstanding, ending balance | shares	2,058,355
Vested and exercisable, ending balance | shares	905,428
Vested and expected to vest, ending balance | shares	1,663,171
WEIGHTED-AVERAGE EXERCISE PRICE
Weighted average exercise prices, outstanding beginning balance | $ / shares	$ 6.09
Weighted average exercise prices, granted | $ / shares	6.07
Weighted average exercise prices, exercised | $ / shares	5.11
Weighted average exercise prices, forfeited | $ / shares	11.97
Weighted average exercise prices, outstanding ending balance | $ / shares	6
Weighted average exercise prices, vested and exercisable ending balance | $ / shares	6.01
Weighted average exercise prices, vested and expected to vest ending balance | $ / shares	$ 5.99
WEIGHTED-AVERAGE REMAINING CONTRACTUAL TERM
Weighted average remaining contractual term, outstanding	8 years 2 months 8 days
Weighted average remaining contractual term, vested and exercisable	7 years 3 days
Weighted average remaining contractual term, vested and expected to vest	7 years 10 months 13 days
AGGREGATE INTRINSIC VALUE
Aggregate intrinsic value, outstanding ending balance | $	$ 4,366
Aggregate intrinsic value, vested and exercisable ending balance | $	2,109
Aggregate intrinsic value, vested and expected to vest ending balance | $	$ 3,702

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of RSU Activity (Details) - Restricted Stock Units (RSUs)	3 Months Ended
	Mar. 31, 2020$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs Outstanding, December 31, 2019 | shares	160,900
RSUs Vested | shares	(38,200)
RSUs outstanding at March 31, 2020 | shares	122,700
AVERAGE GRANT DATE FAIR VALUE, Outstanding, December 31, 2019 | $ / shares	$ 3.25
AVERAGE GRANT DATE FAIR VALUE, Vested | $ / shares	3.25
AVERAGE GRANT DATE FAIR VALUE, RSUs outstanding at March 31, 2020 | $ / shares	$ 3.25

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 508	$ 355
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	144	68
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 364	$ 287

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring $ in Thousands	Mar. 31, 2020USD ($)
Assets:
Cash equivalents	$ 75,070
Total	75,070
Liabilities:
Derivative liability	795
Total	795
Quoted Prices in Active Markets (Level 1) [Member]
Assets:
Cash equivalents	75,070
Total	75,070
Significant Unobservable Inputs (Level 3) [Member]
Liabilities:
Derivative liability	795
Total	$ 795

Term Loan - Additional Informat

Term Loan - Additional Information (Details) - USD ($)	1 Months Ended			3 Months Ended
	Sep. 30, 2019	Nov. 30, 2018	May 31, 2017	Mar. 31, 2020	Mar. 31, 2019
Debt Instrument [Line Items]
Fair value adjustment to derivative liability				$ 30,000
Solar Capital Ltd. and Silicon Valley Bank | 2017 Loan Agreement
Debt Instrument [Line Items]
Loan and security agreement, amount			$ 10,000,000
Loan agreement, maturity date			May 1, 2021
Amortization of debt discount					$ 50,000
Prepayment premium thereafter				1.00%
Final payment fee				$ 250,000
Amortization of final payment fee					$ 30,000
Payment of final fee	$ 325,000
Solar Capital Ltd. and Silicon Valley Bank | 2017 Loan Agreement | Libor
Debt Instrument [Line Items]
Basis spread on variable base rate			8.45%
Solar Capital Ltd. and Silicon Valley Bank | First Amendment to Loan and Security Agreement
Debt Instrument [Line Items]
Final payment fee		$ 325,000
Solar Capital Ltd. and Silicon Valley Bank | 2019 Loan Agreement
Debt Instrument [Line Items]
Loan and security agreement, amount	$ 20,000,000
Loan agreement, maturity date	Sep. 17, 2023
Amortization of debt discount				81,000
Final payment fee				500,000
Amortization of final payment fee				$ 40,000
Loan agreement, term	4 years
Debt instrument, interest rate terms				The interest rate under the 2019 Loan Agreement is the higher of (i) LIBOR plus 7.95% or (ii) 10.18%
Debt instrument, effective interest rate				10.18%
Exit fee, percentage				4.00%
Exit fee				$ 800,000
Derivative liability recorded against exit fee obligation				763,000
Fair value adjustment to derivative liability				30,000
Unpaid borrowings				$ 20,000,000
Prepayment premium percentage after year two				0.50%
Increase in interest rate on default				5.00%
Solar Capital Ltd. and Silicon Valley Bank | 2019 Loan Agreement | Minimum
Debt Instrument [Line Items]
Interest rate, minimum				10.18%
Prepayment premium percentage				1.00%
Solar Capital Ltd. and Silicon Valley Bank | 2019 Loan Agreement | Maximum
Debt Instrument [Line Items]
Prepayment premium percentage				3.00%
Solar Capital Ltd. and Silicon Valley Bank | 2019 Loan Agreement | Libor
Debt Instrument [Line Items]
Basis spread on variable base rate				7.95%

Term Loan - Schedule of Total T

Term Loan - Schedule of Total Term Loan and Unamortized Debt Discount (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term portion	$ 18,996	$ 18,915
2019 Loan Agreement | Solar Capital Ltd. and Silicon Valley Bank
Debt Instrument [Line Items]
Face value	20,000
Less: discount	(1,004)
Total	18,996
Long-term portion	$ 18,996

Term Loan - Schedule of Future

Term Loan - Schedule of Future Principal Payments Due (Details) - 2019 Loan Agreement - Solar Capital Ltd. and Silicon Valley Bank $ in Thousands	Mar. 31, 2020USD ($)
Debt Instrument [Line Items]
December 31, 2021	$ 2,500
December 31, 2022	10,000
December 31, 2023	7,500
Total minimum principal payments	$ 20,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	Aug. 23, 2019	Mar. 31, 2020
Stockholders Equity Note [Line Items]
Common stock, par value		$ 0.0001
ATM Agreement | Legal Accounting and Other Costs
Stockholders Equity Note [Line Items]
Stock issuance cost		$ 189,000
ATM Agreement | Additional Paid-in Capital | Legal Accounting and Other Costs
Stockholders Equity Note [Line Items]
Stock issuance cost		$ 135,000
ATM Agreement | Jefferies | Common Stock
Stockholders Equity Note [Line Items]
Common stock, par value	$ 0.0001
Percentage of commission on gross sales proceeds	3.00%
Number of shares sold		1,502,892
Proceeds from sale of shares,Net		$ 10,400,000
ATM Agreement | Jefferies | Common Stock | Maximum
Stockholders Equity Note [Line Items]
Aggregate offering price	$ 15,000,000
ATM Agreement | Jefferies | Common Stock | Weighted Average
Stockholders Equity Note [Line Items]
Selling price per share		$ 7.13

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended
	Feb. 28, 2018	Mar. 31, 2020	Dec. 31, 2019
Commitments And Contingencies [Line Items]
Operating leases expire		2022
Restricted cash		$ 182,000	$ 182,000
Short-term lease asset		1,092,000	1,179,000
Short-term lease liability		421,000	$ 407,000
Operating sublease term	3 years
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, 2020USD ($)
Year ended:
December 31, 2020	$ 397
December 31, 2021	537
December 31, 2022	496
Total minimum lease payments	1,430
Less imputed interest	(177)
Total	$ 1,253

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, 2020	Mar. 31, 2019
Lease cost:
Operating lease cost	$ 122	$ 125
Short-term lease cost		2
Sublease income	(12)	(13)
Total lease cost	110	114
Other information
Cash paid for amounts included in the measurement of lease liabilities	173	127
Operating cash flows from operating leases	$ (10)	$ (6)
Weighted-average remaining lease term - operating leases	2 years 8 months 12 days	3 years 8 months 12 days
Weighted-average discount rate - operating leases	10.10%	10.10%