scPharmaceuticals (SCPH) 10-Q 11 Aug 21 2021 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2021	Aug. 10, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
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 Current Reporting Status	Yes
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		27,355,454

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 74,969	$ 71,819
Short-term investments	15,052	33,276
Prepaid expenses	2,396	2,610
Other current assets	75	121
Total current assets	92,492	107,826
Restricted cash	182	182
Property and equipment, net	77	93
Right-of-use lease assets - operating, net	616	815
Deposits and other assets	248	132
Total assets	93,615	109,048
Current liabilities
Accounts payable	531	1,666
Accrued expenses	3,579	4,787
Term loan, short-term	7,293	2,408
Lease obligation - operating, short-term	485	460
Total current liabilities	11,888	9,321
Term loan, long-term	12,156	16,858
Lease obligation - operating, long-term	229	480
Other liabilities	299	219
Total liabilities	24,572	26,878
Commitments and contingencies (Note 11)
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 June 30, 2021; 27,325,959 and 27,355,454 shares issued and outstanding as of December 31, 2020 and June 30, 2021, respectively	3	3
Additional paid-in capital	244,868	243,830
Accumulated deficit	(175,828)	(161,664)
Accumulated other comprehensive gain		1
Total stockholders’ equity	69,043	82,170
Total liabilities and stockholders’ equity	$ 93,615	$ 109,048

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
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	27,355,454	27,325,959
Common stock, shares outstanding	27,355,454	27,325,959

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating expenses:
Research and development	$ 3,807	$ 5,139	$ 7,816	$ 9,285
General and administrative	2,649	2,537	5,381	5,040
Total operating expenses	6,456	7,676	13,197	14,325
Loss from operations	(6,456)	(7,676)	(13,197)	(14,325)
Other (expense) income	33	(1)	288	(32)
Interest income	12	21	32	245
Interest expense	(651)	(639)	(1,287)	(1,275)
Net loss	$ (7,062)	$ (8,295)	$ (14,164)	$ (15,387)
Net loss per share — basic and diluted	$ (0.26)	$ (0.36)	$ (0.52)	$ (0.71)
Weighted average common shares outstanding — basic and diluted	27,355,454	23,355,418	27,346,141	21,786,946
Other comprehensive loss:
Unrealized gain (loss) on short-term investments	$ 1		$ (1)
Comprehensive loss	$ (7,061)	$ (8,295)	$ (14,165)	$ (15,387)

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	Other Comprehensive Income
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, net of commissions and issuance costs		$ 10,253				$ 10,253
Issuance of common stock 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
Vesting of restricted stock	(84)				(84)
Vesting of restricted stock, 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
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	(15,387)
Ending Balance at Jun. 30, 2020	98,059		$ 3		242,898		(144,842)
Ending Balance, Shares at Jun. 30, 2020			27,287,997
Beginning Balance at Dec. 31, 2019	51,365		$ 2		180,818		(129,455)
Beginning Balance, Shares at Dec. 31, 2019			19,418,955
Ending Balance at Dec. 31, 2020	82,170		$ 3		243,830		(161,664)	$ 1
Ending Balance, Shares at Dec. 31, 2020			27,325,959
Beginning Balance at Mar. 31, 2020	55,104		$ 2		191,649		(136,547)
Beginning Balance, Shares at Mar. 31, 2020			20,981,880
Net loss	(8,295)						(8,295)
Common stock offering, net of commissions and issuance costs	50,148		$ 1		50,147
Common stock offering, net of commissions and issuance costs, Shares			6,220,589
Issuance of common stock upon exercise of stock options	561				561
Issuance of common stock upon exercise of stock options, Shares			85,528
Vesting of restricted stock	(80)				(80)
Stock-based compensation	621				621
Ending Balance at Jun. 30, 2020	98,059		$ 3		242,898		(144,842)
Ending Balance, Shares at Jun. 30, 2020			27,287,997
Beginning Balance at Dec. 31, 2020	82,170		$ 3		243,830		(161,664)	1
Beginning Balance, Shares at Dec. 31, 2020			27,325,959
Net loss	(7,102)						(7,102)
Issuance of common stock upon exercise of stock options	9				9
Issuance of common stock upon exercise of stock options, Shares			2,500
Vesting of restricted stock	(81)				(81)
Vesting of restricted stock, Shares			26,994
Stock-based compensation	521				521
Unrealized (loss) gain on short-term investments	(2)							(2)
Ending Balance at Mar. 31, 2021	75,515		$ 3		244,279		(168,766)	(1)
Ending Balance, Shares at Mar. 31, 2021			27,355,453
Beginning Balance at Dec. 31, 2020	82,170		$ 3		243,830		(161,664)	1
Beginning Balance, Shares at Dec. 31, 2020			27,325,959
Net loss	$ (14,164)
Issuance of common stock upon exercise of stock options, Shares	2,501
Unrealized (loss) gain on short-term investments	$ (1)
Ending Balance at Jun. 30, 2021	69,043		$ 3		244,868		(175,828)
Ending Balance, Shares at Jun. 30, 2021			27,355,454
Beginning Balance at Mar. 31, 2021	75,515		$ 3		244,279		(168,766)	(1)
Beginning Balance, Shares at Mar. 31, 2021			27,355,453
Net loss	(7,062)						(7,062)
Issuance of common stock upon exercise of stock options, Shares			1
Stock-based compensation	589				589
Unrealized (loss) gain on short-term investments	1							$ 1
Ending Balance at Jun. 30, 2021	$ 69,043		$ 3		$ 244,868		$ (175,828)
Ending Balance, Shares at Jun. 30, 2021			27,355,454

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities
Net loss	$ (14,164,000)	$ (15,387,000)
Adjustments to reconcile net loss to cash used in operating activities
Depreciation expense	16,000	17,000
Amortization expense - right-of-use leased assets - operating	199,000	177,000
Accretion of discount on investments	115,000	(1,000)
Stock-based compensation	1,110,000	1,129,000
Non-cash interest expense	263,000	246,000
Fair value adjustment to derivative liability		30,000
Changes in operating assets and liabilities
Prepaid expenses and other assets	143,000	(259,000)
Accounts payable, accrued expenses and other liabilities	(2,568,000)	343,000
Net cash used in operating activities	(14,886,000)	(13,705,000)
Cash flows from investing activities
Maturities of short-term investments	26,100,000
Purchases of short-term investments	(7,992,000)	(40,469,000)
Net cash (used in) provided by investing activities	18,108,000	(40,469,000)
Cash flows from financing activities
Proceeds from common stock offering, net		50,191,000
Proceeds from at-the-market offering, net		10,388,000
Proceeds from the exercise of vested stock options	9,000	715,000
Payment of term loan exit fee		(800,000)
Settlements of restricted stock units for tax withholding obligations	(81,000)	(84,000)
Net cash provided by (used in) financing activities	(72,000)	60,410,000
Net increase in cash, cash equivalents and restricted cash	3,150,000	6,236,000
Cash, cash equivalents and restricted cash at beginning of period	72,001,000	72,806,000
Cash, cash equivalents and restricted cash at end of period	75,151,000	79,042,000
Supplemental cash flow information
Interest paid	1,114,000	1,436,000
Taxes paid	$ 125,000	144,000
Supplemental non-cash information
Transfer of issuance costs from other noncurrent assets to equity		$ 135,000

Description of Business and Bas

Description of Business and Basis of Presentation	6 Months Ended
	Jun. 30, 2021
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, 2020 included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on March 23, 2021. The Company has determined that it operates in one segment. The accompanying condensed consolidated balance sheet as of June 30, 2021, the condensed consolidated statements of operations and comprehensive loss and stockholders’ equity for the three and six months ended June 30, 2020 and 2021 and condensed consolidated statements of cash flows for the six months ended June 30, 2020 and 2021 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 and six months ended June 30, 2021 are not necessarily indicative of the results expected for the full year ending December 31, 2021. Liquidity As of June 30, 2021, the Company had an accumulated deficit of approximately $175.8 million. As of June 30, 2021, the Company had cash, cash equivalents, restricted cash, and short-term investments of $90.2 million. The Company believes that its existing cash, cash equivalents, restricted cash and short-term investments will be sufficient to meet its cash commitments for at least the next 12 months after the date that the interim condensed consolidated financial statements are issued.

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
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 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 June 30, 2021, 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 11). Cash, cash equivalents and restricted cash consists of the following (in thousands): December 31, 2020 June 30, 2021 Cash and cash equivalents $ 71,819 $ 74,969 Restricted cash 182 182 Cash, cash equivalents and restricted cash $ 72,001 $ 75,151 Concentration of Credit Risk Financial instruments that subject the Company to credit risk primarily consist of cash and cash equivalents and short-term investments. The Company maintains its cash and cash equivalent balances with high-quality financial institutions and, consequently, the Company believes that such funds are subject to minimal credit risk. The Company’s short-term investments consist of United States Treasury securities, corporate debt securities and commercial paper. The Company has adopted an investment policy that limits the amounts the Company may invest in any one type of investment and requires all investments held by the Company to hold a minimum rating, thereby reducing credit risk exposure. Investments The Company invests excess cash balances in available-for-sale debt securities. The Company determines the appropriate classification of these securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company reports available-for-sale investments at fair value at each balance sheet date and includes any unrealized gains and losses in accumulated other comprehensive income (loss), a component of stockholders’ equity. Realized gains and losses are determined using the specific identification method and are included in other income (expense). If any adjustment to fair value reflects a decline in the value of the investment, the Company considers all available evidence to evaluate the extent to which the decline is “other than temporary,” including the intention to sell and, if so, marks the investment to market through a charge to the Company’s consolidated statements of operations and comprehensive loss. 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 June 30, 2021, the Company had no such accruals.

Net Loss per Share

Net Loss per Share	6 Months Ended
	Jun. 30, 2021
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 June 30, Six Months Ended June 30, 2020 2021 2020 2021 Net loss $ (8,295 ) $ (7,062 ) $ (15,387 ) $ (14,164 ) Weighted-average shares used in computing net loss per share 23,355,418 27,355,454 21,786,946 27,346,141 Net loss per share, basic and diluted $ (0.36 ) $ (0.26 ) $ (0.71 ) $ (0.52 ) 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 June 30, Six Months Ended June 30, 2020 2021 2020 2021 Stock options to purchase common stock 2,029,843 2,677,368 2,029,843 2,677,368 Unvested restricted stock units 80,450 42,250 80,450 42,250 Total 2,110,293 2,719,618 2,110,293 2,719,618

Investments

Investments	6 Months Ended
	Jun. 30, 2021
Investments Debt And Equity Securities [Abstract]
Investments	4. Investments Cash in excess of the Company’s immediate requirements is invested in accordance with the Company’s investment policy that primarily seeks to maintain adequate liquidity and preserve capital. A summary of the Company’s available-for-sale classified investments as of June 30, 2021 consisted of the following (in thousands): At June 30, 2021 Investments - Current: Cost Basis Accumulated Unrealized Gains Accumulated Unrealized Losses Fair Value United States Treasury securities $ 1,850 $ - $ - $ 1,850 Corporate debt securities 2,007 - - 2,007 Commercial paper 11,195 - - 11,195 Total $ 15,052 $ - $ - $ 15,052 The amortized cost and fair value of the Company’s available-for-sale investments, by contract maturity, as of June 30, 2021 consisted of the following (in thousands): Amortized Cost Fair Value Due in one year or less $ 15,052 $ 15,052 Total $ 15,052 $ 15,052

Property and Equipment

Property and Equipment	6 Months Ended
	Jun. 30, 2021
Property Plant And Equipment [Abstract]
Property and Equipment	5. Property and Equipment Purchased property and equipment consist of the following (dollars in thousands): ESTIMATED USEFUL LIFE December 31, 2020 June 30, 2021 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 (136 ) (152 ) Property and equipment, net $ 93 $ 77 Depreciation expense for the three months ended June 30, 2020 and June 30, 2021 was $9,000 and $8,000, respectively. Depreciation expense for the six months ended June 30, 2020 and June 30, 2021 was $17,000 and $16,000, respectively.

Accrued Expenses

Accrued Expenses	6 Months Ended
	Jun. 30, 2021
Accrued Liabilities Current [Abstract]
Accrued Expenses	6. Accrued Expenses Accrued expenses consist of the following (in thousands): December 31, 2020 June 30, 2021 Contract research and development $ 2,274 $ 2,069 Employee compensation and related costs 1,978 1,000 Consulting and professional service fees 364 297 Interest 88 85 Financing related costs 43 69 Deposit liability - 40 State taxes 40 19 Total accrued expenses $ 4,787 $ 3,579

Fair Value of Financial Instrum

Fair Value of Financial Instruments	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	7. Fair Value of Financial Instruments The FASB 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 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 tables summarize the Company’s assets 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): As of December 31, 2020 TOTAL Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 70,797 $ 68,798 $ 1,999 $ — Total cash equivalents 70,797 68,798 1,999 — United States Treasury securities 8,213 8,213 — — Corporate debt securities 11,973 — 11,973 — Commercial paper 13,090 — 13,090 — Investments 33,276 8,213 25,063 — Total $ 104,073 $ 77,011 $ 27,062 $ — As of June 30, 2021 TOTAL Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 73,343 $ 71,340 $ 2,003 $ - Total cash equivalents 73,343 71,340 2,003 - United States Treasury securities 1,850 1,850 - - Corporate debt securities 2,007 - 2,007 - Commercial paper 11,195 - 11,195 - Investments 15,052 1,850 13,202 - Total $ 88,395 $ 73,190 $ 15,205 $ -

Term Loan

Term Loan	6 Months Ended
	Jun. 30, 2021
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 SLR Investment Corp. (f/k/a 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. 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 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 June 30, 2021 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 an 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 “Exit Fee”). 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). The Company paid the Exit Fee during 2020 in conjunction with the Company’s public offering, which was deemed to be an exit event pursuant to the Exit Agreement. Prior to its public offering in 2020, the Company recorded $30,000 in non-cash expense as a fair value adjustment to the derivative liability. As of June 30, 2021, unpaid borrowings under the 2019 Loan Agreement totaled $20.0 million. For the three and six months ended June 30, 2021, the Company recorded $95,000 and $182,000, respectively, related to the amortization of debt discount associated with the 2019 Loan Agreement. For the three and six months ended June 30, 2020, the Company recorded $85,000 and $166,000, respectively, 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 and six months ended June 30, 2021, the Company recorded $41,000 and $81,000, respectively, 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): June 30, 2021 Face value $ 20,000 Less: discount (551 ) Total $ 19,449 Less: current portion (7,293 ) Total $ 12,156 As of June 30, 2021, 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 $ 20,000

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Stockholders' Equity	9. Stockholders’ Equity 2019 At-the-Market Issuance Sales Agreement On August 23, 2019, the Company entered into an Open Market Sale Agreement SM The Company agreed to pay Jefferies a commission equal to 3.0% of the gross sales proceeds of such 2019 ATM Shares. The Company incurred $189,000 of legal, accounting and other costs to establish and activate the 2019 ATM program. During 2020, the Company sold a total of 1,502,892 2019 ATM Shares under the 2019 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 program. The Company charged $135,000 in costs related to establishing and activating the program against additional paid in capital upon issuance of shares during 2020. 2021 At-the-Market Issuance Sales Agreement On March 23, 2021, the Company entered into an Open Market Sale Agreement (the “2021 ATM Agreement”) with Cowen and Company, LLC (“Cowen”) with respect to an at-the-market offering program (the “2021 ATM Program”) under which the Company could offer and sell shares of its common stock (the “2021 ATM Shares”), having an aggregate offering price of up to $50.0 million through Cowen as its sales agent. The Company agreed to pay Cowen a commission up to 3.0% of the gross sales proceeds of such 2021 ATM Shares. As of June 30, 2021, the Company had received no proceeds from the sale of shares of common stock pursuant to the 2021 ATM Agreement. Sale of Common Stock In May 2020, the Company completed an underwritten public offering of 5,780,347 shares of its common stock (the “2020 Offering Shares”), pursuant to the Registration Statement. The 2020 Offering Shares were sold at an offering price of $8.65 per share, resulting in net proceeds of $46.6 million, after deducting underwriting discounts, commissions and offering expenses. In addition, the underwriters of the offering were granted the option for a period of 30 days to purchase up to an additional 867,052 shares of common stock at $8.65 per share. In June 2020, the underwriters exercised their option and purchased an additional 440,242 shares of common stock at $8.65 per share, resulting in additional net proceeds to the Company of $3.6 million, after deducting underwriting discounts, commissions and offering expenses.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	10. Stock-Based Compensation Stock Options The Company’s 2017 Stock Option and Incentive Plan (the “2017 Stock Plan”) became effective in November 2017 October 2027 November 2017 As of June 30, 2021, there were 5,051,920 shares of the Company’s common stock authorized for issuance under the 2017 Stock Plan, including 359,651 options that have been forfeited from the 2014 Stock Plan. At June 30, 2021, there were 2,903,186 options available for issuance under the 2017 Stock Plan, 2,076,680 options outstanding and 42,250 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 The fair value of options at date of grant was estimated using the Black-Scholes option-pricing model with the following assumptions: Six Months Ended June 30, 2020 2021 Risk-free interest rate 0.41% - 1.71% 0.50% - 0.88% Expected dividend yield 0% 0% Expected life 5.5-6.6 years 5.5-6.7 years Expected volatility 72%-75% 72%-74% Weighted-average grant date fair value $ 4.06 $ 4.26 The following table summarizes information about stock option activity during the six months ended June 30, 2021 (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, 2020 2,224,913 $ 6.26 Granted 899,506 6.70 Exercised (2,501 ) 3.81 Forfeited (444,550 ) 6.58 Outstanding, June 30, 2021 2,677,368 $ 6.35 7.97 $ 2,023 Vested and exercisable, June 30, 2021 1,206,154 $ 5.85 6.52 $ 1,722 Vested and expected to vest, June 30, 2021 2,137,511 $ 6.28 7.65 $ 1,904 Of the options granted during the six months ended June 30, 2021, 112,050 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 six months ended June 30, 2021: RSUs AVERAGE GRANT DATE FAIR VALUE (IN DOLLARS PER SHARE) Outstanding, December 31, 2020 80,450 $ 3.25 Granted — — Vested (38,200 ) 3.25 Forfeited — — RSUs outstanding at June 30, 2021 42,250 $ 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 June 30, 2021 was $3.5 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 2.5 years. Unrecognized compensation expense related to unvested RSUs as of June 30, 2021 was $30,000 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 1 year. 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 and six months ended June 30, 2020 and 2021 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2020 2021 2020 2021 Research and development $ 177 $ 233 $ 321 $ 459 General and administrative 444 356 808 651 Total $ 621 $ 589 $ 1,129 $ 1,110

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	11 . 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 June 30, 2021 (in thousands): Year ended: December 31, 2021 $ 265 December 31, 2022 496 Total minimum lease payments 761 Less imputed interest (47 ) Total $ 714 Six Months Ended June 30, 2020 2021 Lease cost: Operating lease cost $ 243 $ 244 Short-term lease cost - - Sublease income (25 ) (26 ) Total lease cost $ 218 $ 218 Other information Cash paid for amounts included in the measurement of lease liabilities $ 267 $ 262 Operating cash flows from operating leases $ (20 ) $ (28 ) Weighted-average remaining lease term - operating leases 2.4 years 1.4 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. In February 2020, the sublease was extended until December 31, 2022. Research and Development Agreements As part of the Company’s research and development efforts, the Company enters into research and development agreements with certain companies. These agreements contain varying terms and provisions which include fees and milestones to be paid by the Company. Some of these agreements also contain provisions which require the Company to make payments for exclusivity in the development of products in the area of loop diuretics. 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 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)	6 Months Ended
	Jun. 30, 2021
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 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 June 30, 2021, 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 11). Cash, cash equivalents and restricted cash consists of the following (in thousands): December 31, 2020 June 30, 2021 Cash and cash equivalents $ 71,819 $ 74,969 Restricted cash 182 182 Cash, cash equivalents and restricted cash $ 72,001 $ 75,151
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that subject the Company to credit risk primarily consist of cash and cash equivalents and short-term investments. The Company maintains its cash and cash equivalent balances with high-quality financial institutions and, consequently, the Company believes that such funds are subject to minimal credit risk. The Company’s short-term investments consist of United States Treasury securities, corporate debt securities and commercial paper. The Company has adopted an investment policy that limits the amounts the Company may invest in any one type of investment and requires all investments held by the Company to hold a minimum rating, thereby reducing credit risk exposure.
Investments	Investments The Company invests excess cash balances in available-for-sale debt securities. The Company determines the appropriate classification of these securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company reports available-for-sale investments at fair value at each balance sheet date and includes any unrealized gains and losses in accumulated other comprehensive income (loss), a component of stockholders’ equity. Realized gains and losses are determined using the specific identification method and are included in other income (expense). If any adjustment to fair value reflects a decline in the value of the investment, the Company considers all available evidence to evaluate the extent to which the decline is “other than temporary,” including the intention to sell and, if so, marks the investment to market through a charge to the Company’s consolidated statements of operations and comprehensive loss.
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 June 30, 2021, the Company had no such accruals.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Schedule of Cash, Cash Equivalents and Restricted Cash	As of June 30, 2021, 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 11). Cash, cash equivalents and restricted cash consists of the following (in thousands): December 31, 2020 June 30, 2021 Cash and cash equivalents $ 71,819 $ 74,969 Restricted cash 182 182 Cash, cash equivalents and restricted cash $ 72,001 $ 75,151

Net Loss per Share (Tables)

Net Loss per Share (Tables)	6 Months Ended
	Jun. 30, 2021
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 June 30, Six Months Ended June 30, 2020 2021 2020 2021 Net loss $ (8,295 ) $ (7,062 ) $ (15,387 ) $ (14,164 ) Weighted-average shares used in computing net loss per share 23,355,418 27,355,454 21,786,946 27,346,141 Net loss per share, basic and diluted $ (0.36 ) $ (0.26 ) $ (0.71 ) $ (0.52 )
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 June 30, Six Months Ended June 30, 2020 2021 2020 2021 Stock options to purchase common stock 2,029,843 2,677,368 2,029,843 2,677,368 Unvested restricted stock units 80,450 42,250 80,450 42,250 Total 2,110,293 2,719,618 2,110,293 2,719,618

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2021
Investments Debt And Equity Securities [Abstract]
Summary of Available-for-Sale Classified Investments	A summary of the Company’s available-for-sale classified investments as of June 30, 2021 consisted of the following (in thousands): At June 30, 2021 Investments - Current: Cost Basis Accumulated Unrealized Gains Accumulated Unrealized Losses Fair Value United States Treasury securities $ 1,850 $ - $ - $ 1,850 Corporate debt securities 2,007 - - 2,007 Commercial paper 11,195 - - 11,195 Total $ 15,052 $ - $ - $ 15,052
Summary of Amortized Cost and Fair Value of Available-for-Sale Investments by Contract Maturity	The amortized cost and fair value of the Company’s available-for-sale investments, by contract maturity, as of June 30, 2021 consisted of the following (in thousands): Amortized Cost Fair Value Due in one year or less $ 15,052 $ 15,052 Total $ 15,052 $ 15,052

Property and Equipment (Tables)

Property and Equipment (Tables)	6 Months Ended
	Jun. 30, 2021
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, 2020 June 30, 2021 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 (136 ) (152 ) Property and equipment, net $ 93 $ 77

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Jun. 30, 2021
Accrued Liabilities Current [Abstract]
Schedule of Accrued Expenses	Accrued expenses consist of the following (in thousands): December 31, 2020 June 30, 2021 Contract research and development $ 2,274 $ 2,069 Employee compensation and related costs 1,978 1,000 Consulting and professional service fees 364 297 Interest 88 85 Financing related costs 43 69 Deposit liability - 40 State taxes 40 19 Total accrued expenses $ 4,787 $ 3,579

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Summary of Assets Measured at Fair Value on Recurring Basis	The following tables summarize the Company’s assets 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): As of December 31, 2020 TOTAL Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 70,797 $ 68,798 $ 1,999 $ — Total cash equivalents 70,797 68,798 1,999 — United States Treasury securities 8,213 8,213 — — Corporate debt securities 11,973 — 11,973 — Commercial paper 13,090 — 13,090 — Investments 33,276 8,213 25,063 — Total $ 104,073 $ 77,011 $ 27,062 $ — As of June 30, 2021 TOTAL Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 73,343 $ 71,340 $ 2,003 $ - Total cash equivalents 73,343 71,340 2,003 - United States Treasury securities 1,850 1,850 - - Corporate debt securities 2,007 - 2,007 - Commercial paper 11,195 - 11,195 - Investments 15,052 1,850 13,202 - Total $ 88,395 $ 73,190 $ 15,205 $ -

Term Loan (Tables)

Term Loan (Tables)	6 Months Ended
	Jun. 30, 2021
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): June 30, 2021 Face value $ 20,000 Less: discount (551 ) Total $ 19,449 Less: current portion (7,293 ) Total $ 12,156
Schedule of Future Principal Payments Due	As of June 30, 2021, 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 $ 20,000

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2021
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: Six Months Ended June 30, 2020 2021 Risk-free interest rate 0.41% - 1.71% 0.50% - 0.88% Expected dividend yield 0% 0% Expected life 5.5-6.6 years 5.5-6.7 years Expected volatility 72%-75% 72%-74% Weighted-average grant date fair value $ 4.06 $ 4.26
Summary of Information about Stock Option Activity	The following table summarizes information about stock option activity during the six months ended June 30, 2021 (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, 2020 2,224,913 $ 6.26 Granted 899,506 6.70 Exercised (2,501 ) 3.81 Forfeited (444,550 ) 6.58 Outstanding, June 30, 2021 2,677,368 $ 6.35 7.97 $ 2,023 Vested and exercisable, June 30, 2021 1,206,154 $ 5.85 6.52 $ 1,722 Vested and expected to vest, June 30, 2021 2,137,511 $ 6.28 7.65 $ 1,904
Schedule of RSU Activity	The following table summarizes information about RSU activity during the six months ended June 30, 2021: RSUs AVERAGE GRANT DATE FAIR VALUE (IN DOLLARS PER SHARE) Outstanding, December 31, 2020 80,450 $ 3.25 Granted — — Vested (38,200 ) 3.25 Forfeited — — RSUs outstanding at June 30, 2021 42,250 $ 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 and six months ended June 30, 2020 and 2021 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2020 2021 2020 2021 Research and development $ 177 $ 233 $ 321 $ 459 General and administrative 444 356 808 651 Total $ 621 $ 589 $ 1,129 $ 1,110

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2021
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 June 30, 2021 (in thousands): Year ended: December 31, 2021 $ 265 December 31, 2022 496 Total minimum lease payments 761 Less imputed interest (47 ) Total $ 714
Schedule of Lease Cost and Other Information of Operating Lease Liabilities	Six Months Ended June 30, 2020 2021 Lease cost: Operating lease cost $ 243 $ 244 Short-term lease cost - - Sublease income (25 ) (26 ) Total lease cost $ 218 $ 218 Other information Cash paid for amounts included in the measurement of lease liabilities $ 267 $ 262 Operating cash flows from operating leases $ (20 ) $ (28 ) Weighted-average remaining lease term - operating leases 2.4 years 1.4 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) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Accumulated deficit	$ (175,828)	$ (161,664)
Cash, cash equivalents, restricted cash, and short-term investments	$ 90,200

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Details) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
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	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 74,969	$ 71,819
Restricted cash	182	182
Cash, cash equivalents and restricted cash	$ 75,151	$ 72,001	$ 79,042	$ 72,806

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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Net loss	$ (7,062)	$ (8,295)	$ (14,164)	$ (15,387)
Weighted-average shares used in computing net loss per share	27,355,454	23,355,418	27,346,141	21,786,946
Net loss per share, basic and diluted	$ (0.26)	$ (0.36)	$ (0.52)	$ (0.71)

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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	2,719,618	2,110,293	2,719,618	2,110,293
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	2,677,368	2,029,843	2,677,368	2,029,843
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	42,250	80,450	42,250	80,450

Investments - Summary of Availa

Investments - Summary of Available-for-Sale Classified Investments (Details) $ in Thousands	Jun. 30, 2021USD ($)
Marketable Securities [Line Items]
Cost Basis	$ 15,052
Fair Value	15,052
United States Treasury Securities
Marketable Securities [Line Items]
Cost Basis	1,850
Fair Value	1,850
Corporate Debt Securities
Marketable Securities [Line Items]
Cost Basis	2,007
Fair Value	2,007
Commercial Paper
Marketable Securities [Line Items]
Cost Basis	11,195
Fair Value	$ 11,195

Investments - Summary of Amorti

Investments - Summary of Amortized Cost and Fair Value of Available-for-Sale Investments by Contract Maturity (Details) $ in Thousands	Jun. 30, 2021USD ($)
Investments Debt And Equity Securities [Abstract]
Amortized Cost, Due in one year or less	$ 15,052
Amortized Cost, Total	15,052
Fair Value, Due in one year or less	15,052
Fair Value, Total	$ 15,052

Property and Equipment - Schedu

Property and Equipment - Schedule of Purchased Property and Equipment (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 229	$ 229
Less: Accumulated depreciation	(152)	(136)
Property and equipment, net	$ 77	93
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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Property Plant And Equipment [Abstract]
Depreciation expense	$ 8,000	$ 9,000	$ 16,000	$ 17,000

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Accrued Liabilities Current [Abstract]
Contract research and development	$ 2,069	$ 2,274
Employee compensation and related costs	1,000	1,978
Consulting and professional service fees	297	364
Interest	85	88
Financing related costs	69	43
Deposit liability	40
State taxes	19	40
Total accrued expenses	$ 3,579	$ 4,787

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Summary of Assets Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Assets:
Cash equivalents	$ 73,343	$ 70,797
Investments	15,052	33,276
Total	88,395	104,073
United States Treasury Securities
Assets:
Investments		8,213
Corporate Debt Securities
Assets:
Investments	2,007	11,973
Commercial Paper
Assets:
Investments	11,195	13,090
United States Treasury Securities
Assets:
Investments	1,850
Quoted Prices in Active Markets (Level 1) [Member]
Assets:
Cash equivalents	71,340	68,798
Investments	1,850	8,213
Total	73,190	77,011
Quoted Prices in Active Markets (Level 1) [Member] | United States Treasury Securities
Assets:
Investments		8,213
Quoted Prices in Active Markets (Level 1) [Member] | United States Treasury Securities
Assets:
Investments	1,850
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Cash equivalents	2,003	1,999
Investments	13,202	25,063
Total	15,205	27,062
Significant Other Observable Inputs (Level 2) [Member] | Corporate Debt Securities
Assets:
Investments	2,007	11,973
Significant Other Observable Inputs (Level 2) [Member] | Commercial Paper
Assets:
Investments	$ 11,195	$ 13,090

Term Loan - Additional Informat

Term Loan - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended		6 Months Ended
	Sep. 30, 2019	May 31, 2017	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Instrument [Line Items]
Fair value adjustment to derivative liability						$ 30,000
SLR Investment Corp. 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
Payment of final fee	$ 325,000
Unpaid borrowings		$ 10,000,000
SLR Investment Corp. and Silicon Valley Bank | 2019 Loan Agreement
Debt Instrument [Line Items]
Loan and security agreement, amount	$ 20,000,000		$ 20,000,000		$ 20,000,000
Loan agreement, maturity date	Sep. 17, 2023
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%		10.18%
Exit fee, percentage					4.00%
Exit fee					$ 800,000
Derivative liability recorded against exit fee obligation			$ 763,000		763,000
Fair value adjustment to derivative liability					30,000
Unpaid borrowings	$ 20,000,000		20,000,000		20,000,000
Amortization of debt discount			95,000	$ 85,000	$ 182,000	166,000
Prepayment premium percentage after year two					0.50%
Final payment fee					$ 500,000
Amortization of final payment fee			$ 41,000	$ 40,000	$ 81,000	$ 80,000
Increase in interest rate on default					5.00%
SLR Investment Corp. and Silicon Valley Bank | 2019 Loan Agreement | Minimum
Debt Instrument [Line Items]
Interest rate, minimum			10.18%		10.18%
Prepayment premium percentage					1.00%
SLR Investment Corp. and Silicon Valley Bank | 2019 Loan Agreement | Maximum
Debt Instrument [Line Items]
Prepayment premium percentage					3.00%
SLR Investment Corp. 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	Jun. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Less: current portion	$ (7,293)	$ (2,408)
Total	12,156	$ 16,858
2019 Loan Agreement | SLR Investment Corp. and Silicon Valley Bank
Debt Instrument [Line Items]
Loan and security agreement, amount	20,000
Less: discount	(551)
Total	19,449
Less: current portion	(7,293)
Total	$ 12,156

Term Loan - Schedule of Future

Term Loan - Schedule of Future Principal Payments Due (Details) - 2019 Loan Agreement - SLR Investment Corp. and Silicon Valley Bank $ in Thousands	Jun. 30, 2021USD ($)
Debt Instrument [Line Items]
December 31, 2021	$ 2,500
December 31, 2022	10,000
December 31, 2023	7,500
Total	$ 20,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	Mar. 23, 2021	Aug. 23, 2019	Jun. 30, 2020	May 31, 2020	Jun. 30, 2021	Dec. 31, 2020
2019 ATM Agreement | Legal Accounting and Other Costs
Stockholders Equity Note [Line Items]
Stock issuance cost		$ 189,000
2019 ATM Agreement | Additional Paid-in Capital | Legal Accounting and Other Costs
Stockholders Equity Note [Line Items]
Stock issuance cost						$ 135,000
2019 ATM Agreement | Jefferies | Common Stock
Stockholders Equity Note [Line Items]
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
Issuance of common stock net of commissions and issuance costs, Shares						1,502,892
2019 ATM Agreement | Jefferies | Common Stock | Maximum
Stockholders Equity Note [Line Items]
Aggregate offering price		$ 15,000,000
2019 ATM Agreement | Jefferies | Common Stock | Weighted Average
Stockholders Equity Note [Line Items]
Selling price per share						$ 7.13
Selling price per share						$ 7.13
2021 ATM Agreement | Cowen | Common Stock
Stockholders Equity Note [Line Items]
Proceeds from sale of shares,Net					$ 0
2021 ATM Agreement | Cowen | Common Stock | Maximum
Stockholders Equity Note [Line Items]
Aggregate offering price	$ 50,000,000
Percentage of commission on gross sales proceeds	3.00%
Underwritten Public Offering | Common Stock
Stockholders Equity Note [Line Items]
Number of shares sold			440,242	5,780,347
Selling price per share			$ 8.65	$ 8.65
Proceeds from sale of shares,Net			$ 3,600,000	$ 46,600,000
Issuance of common stock net of commissions and issuance costs, Shares			440,242	5,780,347
Selling price per share			$ 8.65	$ 8.65
Underwritten Public Offering | Common Stock | Maximum
Stockholders Equity Note [Line Items]
Option granted to purchase additional shares				867,052

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional options granted	899,506
Stock option, number of shares outstanding	2,677,368	2,224,913
Unrecognized compensation expense	$ 3,500,000
Recognition period (in years)	2 years 6 months
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense	$ 30,000
Recognition period (in years)	1 year
Performance Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional options granted	112,050
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	2,076,680
Number of common shares authorized for issuance	5,051,920
Stock options, available for issuance	2,903,186
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
2017 Stock Plan | Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of restricted stock units outstanding	42,250
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	600,688
Number of options forfeited	359,651

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Estimated Fair Value of Options Valuation Assumptions (Details) - $ / shares	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	0.50%	0.41%
Risk-free interest rate, maximum	0.88%	1.71%
Expected dividend yield	0.00%	0.00%
Expected volatility, minimum	72.00%	72.00%
Expected volatility, maximum	74.00%	75.00%
Weighted-average grant date fair value	$ 4.26	$ 4.06
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life	5 years 6 months	5 years 6 months
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life	6 years 8 months 12 days	6 years 7 months 6 days

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Information about Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2021
NUMBER OF SHARES
Number of shares outstanding, beginning balance	2,224,913
Additional options granted	899,506
Number of shares exercised	(2,501)
Number of shares forfeited	(444,550)
Number of shares outstanding, ending balance	2,677,368
Vested and exercisable, ending balance	1,206,154
Vested and expected to vest, ending balance	2,137,511
WEIGHTED-AVERAGE EXERCISE PRICE
Weighted average exercise prices, outstanding beginning balance	$ 6.26
Weighted average exercise prices, granted	6.70
Weighted average exercise prices, exercised	3.81
Weighted average exercise prices, forfeited	6.58
Weighted average exercise prices, outstanding ending balance	6.35
Weighted average exercise prices, vested and exercisable ending balance	5.85
Weighted average exercise prices, vested and expected to vest ending balance	$ 6.28
WEIGHTED-AVERAGE REMAINING CONTRACTUAL TERM
Weighted average remaining contractual term, outstanding	7 years 11 months 19 days
Weighted average remaining contractual term, vested and exercisable	6 years 6 months 7 days
Weighted average remaining contractual term, vested and expected to vest	7 years 7 months 24 days
AGGREGATE INTRINSIC VALUE
Aggregate intrinsic value, outstanding ending balance	$ 2,023
Aggregate intrinsic value, vested and exercisable ending balance	1,722
Aggregate intrinsic value, vested and expected to vest ending balance	$ 1,904

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of RSU Activity (Details) - Restricted Stock Units (RSUs)	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs Outstanding, December 31, 2020 | shares	80,450
RSUs Vested | shares	(38,200)
RSUs outstanding at June 30, 2021 | shares	42,250
AVERAGE GRANT DATE FAIR VALUE, Outstanding, December 31, 2020 | $ / shares	$ 3.25
AVERAGE GRANT DATE FAIR VALUE, Vested | $ / shares	3.25
AVERAGE GRANT DATE FAIR VALUE, RSUs outstanding at June 30, 2021 | $ / shares	$ 3.25

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 589	$ 621	$ 1,110	$ 1,129
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	233	177	459	321
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 356	$ 444	$ 651	$ 808

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	1 Months Ended	6 Months Ended
	Feb. 28, 2018	Jun. 30, 2021	Dec. 31, 2020
Commitments And Contingencies [Line Items]
Operating leases expire		2022
Restricted cash		$ 182,000	$ 182,000
Short-term lease asset		616,000	815,000
Short-term lease liability		485,000	$ 460,000
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	Jun. 30, 2021USD ($)
Year ended:
December 31, 2021	$ 265
December 31, 2022	496
Total minimum lease payments	761
Less imputed interest	(47)
Total	$ 714

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Lease Cost and Other Information of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Lease cost:
Operating lease cost	$ 244	$ 243
Sublease income	(26)	(25)
Total lease cost	218	218
Other information
Cash paid for amounts included in the measurement of lease liabilities	262	267
Operating cash flows from operating leases	$ (28)	$ (20)
Weighted-average remaining lease term - operating leases	1 year 4 months 24 days	2 years 4 months 24 days
Weighted-average discount rate - operating leases	10.10%	10.10%