Eloxx Pharmaceuticals (ELOX) 10-Q 7 Aug 20 2020 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2020	Aug. 03, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Trading Symbol	ELOX
Entity Registrant Name	ELOXX PHARMACEUTICALS, INC.
Entity Central Index Key	0001035354
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		40,137,693
Entity Small Business	true
Entity Emerging Growth Company	false
Entity File Number	001-31326
Entity Tax Identification Number	84-1368850
Entity Address, Address Line One	950 Winter Street
Entity Address, City or Town	Waltham
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02451
City Area Code	781
Local Phone Number	577-5300
Entity Incorporation State Country Code	DE
Entity Shell Company	false
Entity Current Reporting Status	Yes
Security12b Title	Common Stock, $0.01 par value per share
Entity Interactive Data Current	Yes
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 30,347	$ 22,493
Marketable securities	6,769	33,783
Restricted cash	52	43
Prepaid expenses and other current assets	1,800	1,390
Total current assets	38,968	57,709
Property and equipment, net	165	201
Operating lease right-of-use asset	678	924
Other long-term assets	110	113
Total assets	39,921	58,947
Current liabilities:
Accounts payable	770	1,871
Accrued expenses	3,485	4,655
Current portion of long-term debt	5,149	4,336
Advances from collaboration partners	805	403
Current portion of operating lease liability	524	499
Taxes payable	38	43
Total current liabilities	10,771	11,807
Long-term debt	8,704	10,502
Operating lease liability	155	425
Total liabilities	19,630	22,734
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.01 par value per share, 5,000,000 shares authorized, no shares issued or outstanding as of June 30, 2020 and December 31, 2019
Common stock, $0.01 par value per share, 500,000,000 shares authorized, 40,326,906 and 40,186,469 shares issued, and 40,135,290 and 40,030,763 shares outstanding as of June 30, 2020 and December 31, 2019, respectively	403	402
Common stock in treasury, at cost, 191,616 and 155,706 shares as of June 30, 2020 and December 31, 2019, respectively	(1,822)	(1,703)
Additional paid-in capital	180,549	174,515
Accumulated other comprehensive income	13	18
Accumulated deficit	(158,852)	(137,019)
Total stockholders’ equity	20,291	36,213
Total liabilities and stockholders’ equity	$ 39,921	$ 58,947

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred Stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred Stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	40,326,906	40,186,469
Common stock, shares outstanding	40,135,290	40,030,763
Common stock, treasury shares	191,616	155,706

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating expenses:
Research and development	$ 3,528	$ 7,340	$ 8,077	$ 13,359
General and administrative	4,058	6,971	9,282	12,929
Restructuring charges			3,994
Total operating expenses	7,586	14,311	21,353	26,288
Loss from operations	(7,586)	(14,311)	(21,353)	(26,288)
Other expense (income), net	301	138	480	78
Net loss	$ (7,887)	$ (14,449)	$ (21,833)	$ (26,366)
Net loss per share, basic and diluted	$ (0.20)	$ (0.40)	$ (0.54)	$ (0.73)
Weighted average number of shares of common stock used in computing net loss per share, basic and diluted	40,129,304	36,278,567	40,101,789	36,098,171
Comprehensive loss:
Net loss	$ (7,887)	$ (14,449)	$ (21,833)	$ (26,366)
Other comprehensive income (loss):
Change in unrealized gain (loss) on available-for-sale securities	(52)	23	(5)	24
Comprehensive loss	$ (7,939)	$ (14,426)	$ (21,838)	$ (26,342)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net loss	$ (21,833)	$ (26,366)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	5,971	5,674
Depreciation	36	50
Amortization of operating lease right-of-use asset	246	231
Amortization of debt discount	301	234
Amortization, net, of premiums and discounts on investments	9	(109)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(449)	339
Accounts payable	(1,101)	1,726
Accrued expenses	(1,170)	(281)
Operating lease liabilities	(245)	(231)
Taxes payable	(5)	(79)
Net cash used in operating activities	(18,240)	(18,812)
Cash flows from investing activities:
Purchases of marketable securities		(33,590)
Proceeds from maturities of marketable securities	27,000	6,750
Purchase of property and equipment		(16)
Cash received (paid) for long-term deposits	42	(9)
Net cash provided by (used in) investing activities	27,042	(26,865)
Cash flows from financing activities:
Proceeds from underwritten public offering, net of issuance costs		455
Proceeds from debt financing obligation	797	15,000
Payment of debt issuance costs		(276)
Repayment of term loan principal	(2,083)
Proceeds from exercises of stock options	64	116
Payment for settlement of taxes upon vesting of restricted stock units	(119)	(1,120)
Proceeds from advances from collaboration partners	402
Net cash (used in) provided by financing activities	(939)	46,397
Increase in cash, cash equivalents and restricted cash	7,863	720
Cash, cash equivalents and restricted cash at the beginning of the period	22,536	48,651
Cash, cash equivalents and restricted cash at the end of the period	30,399	49,371
Reconciliation of cash, cash equivalents and restricted cash to condensed consolidated balance sheets:
Cash and cash equivalents	30,347	49,326
Restricted cash	52	45
Cash, cash equivalents and restricted cash at the end of the period	30,399	49,371
Supplemental disclosure of cash flow activities:
Cash paid for interest	481	400
Cash paid for income taxes	$ 5	79
Supplemental disclosure of non-cash financing activities:
Non-cash acquisition of treasury stock		95
Non-cash issuance of common stock upon exercise of warrants		178
Fair value of warrants issued in connection with long-term debt		421
Deferred public offering costs in accounts payable and accrued expenses		172
Underwritten Public Offering
Cash flows from financing activities:
Proceeds from underwritten public offering, net of issuance costs		$ 32,222

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	At-the-market Sale Agreement [Member]	Public Offering [Member]	Common Stock [Member]	Common Stock [Member]At-the-market Sale Agreement [Member]	Common Stock [Member]Public Offering [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]At-the-market Sale Agreement [Member]	Additional Paid-in Capital [Member]Public Offering [Member]	Accumulated Other Comprehensive Income [Member]	Treasury stock [Member]	Accumulated deficit [Member]
Balance at Dec. 31, 2018	$ 42,911			$ 360			$ 129,825				$ (1,129)	$ (86,145)
Balance, shares at Dec. 31, 2018				35,860,114							(91,423)
Exercise of stock options	25						25
Exercise of stock options, shares				25,000
Issuance of stock		$ 455			$ 1			$ 454
Issuance of stock, shares					35,362
Issuance of warrants	421						421
Vesting of restricted stock units	(121)										$ (121)
Vesting of restricted stock units, shares				25,132							(10,467)
Stock-based compensation expense	2,658						2,658
Change in unrealized gain (loss) on investments	1									$ 1
Net loss	(11,917)											(11,917)
Balance at Mar. 31, 2019	34,433			$ 361			133,383			1	$ (1,250)	(98,062)
Balance, shares at Mar. 31, 2019				35,945,608							(101,890)
Balance at Dec. 31, 2018	42,911			$ 360			129,825				$ (1,129)	(86,145)
Balance, shares at Dec. 31, 2018				35,860,114							(91,423)
Change in unrealized gain (loss) on investments	24
Net loss	(26,366)
Balance at Jun. 30, 2019	55,224			$ 402			168,848			24	$ (1,539)	(112,511)
Balance, shares at Jun. 30, 2019				39,914,668							(128,697)
Balance at Mar. 31, 2019	34,433			$ 361			133,383			1	$ (1,250)	(98,062)
Balance, shares at Mar. 31, 2019				35,945,608							(101,890)
Exercise of stock options	90						90
Exercise of stock options, shares				36,790
Issuance of stock, shares						3,833,334
Issuance of common stock upon exercise of warrants							178				$ (178)
Issuance of common stock upon exercise of warrants, shares				44,814							(14,893)
Vesting of restricted stock units	(111)			$ 3			(3)				$ (111)
Vesting of restricted stock units, shares				54,122							(11,914)
Issuance of stock			$ 32,222			$ 38			$ 32,184
Stock-based compensation expense	3,016						3,016
Change in unrealized gain (loss) on investments	23									23
Net loss	(14,449)											(14,449)
Balance at Jun. 30, 2019	55,224			$ 402			168,848			24	$ (1,539)	(112,511)
Balance, shares at Jun. 30, 2019				39,914,668							(128,697)
Balance at Dec. 31, 2019	$ 36,213			$ 402			174,515			18	$ (1,703)	(137,019)
Balance, shares at Dec. 31, 2019	40,030,763			40,030,763							(155,706)
Exercise of stock options	$ 64						64
Exercise of stock options, shares				10,636
Vesting of restricted stock units	(116)			$ 1			(1)				$ (116)
Vesting of restricted stock units, shares				84,055							(34,874)
Stock-based compensation expense	3,995						3,995
Change in unrealized gain (loss) on investments	47									47
Net loss	(13,946)											(13,946)
Balance at Mar. 31, 2020	26,257			$ 403			178,573			65	$ (1,819)	(150,965)
Balance, shares at Mar. 31, 2020				40,125,454							(190,580)
Balance at Dec. 31, 2019	$ 36,213			$ 402			174,515			18	$ (1,703)	(137,019)
Balance, shares at Dec. 31, 2019	40,030,763			40,030,763							(155,706)
Exercise of stock options, shares	10,636
Issuance of warrants	$ 400
Change in unrealized gain (loss) on investments	(5)
Net loss	(21,833)
Balance at Jun. 30, 2020	$ 20,291			$ 403			180,549			13	$ (1,822)	(158,852)
Balance, shares at Jun. 30, 2020	40,135,290			40,135,290							(191,616)
Balance at Mar. 31, 2020	$ 26,257			$ 403			178,573			65	$ (1,819)	(150,965)
Balance, shares at Mar. 31, 2020				40,125,454							(190,580)
Vesting of restricted stock units	(3)										$ (3)
Vesting of restricted stock units, shares				9,836							(1,036)
Stock-based compensation expense	1,976						1,976
Change in unrealized gain (loss) on investments	(52)									(52)
Net loss	(7,887)											(7,887)
Balance at Jun. 30, 2020	$ 20,291			$ 403			$ 180,549			$ 13	$ (1,822)	$ (158,852)
Balance, shares at Jun. 30, 2020	40,135,290			40,135,290							(191,616)

Nature of the Business

Nature of the Business	6 Months Ended
	Jun. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of the Business	1. Nature of the Business Eloxx Pharmaceuticals, Inc., together with its subsidiaries (collectively “Eloxx” or the “Company”), is a clinical-stage biopharmaceutical company developing novel ribonucleic acid (RNA)-modulating drug candidates, each designed to be a eukaryotic ribosomal selective glycoside (ERSG), formulated to treat rare and ultra-rare premature stop codon diseases. Premature stop codons are point mutations that disrupt the stability of the impacted messenger RNA (mRNA) and the protein synthesis from that mRNA. As a consequence, patients with premature stop codon diseases have reduced levels of, or no, protein from a gene whose product performs an essential function. This type of mutation accounts for some of the most severe phenotypes across genetic diseases. Nonsense mutations have been identified in over 1,800 rare and ultra-rare diseases. Read-through therapeutic development is focused on increasing functional protein synthesis by enabling the cytoplasmic ribosome to read through premature stop codons to produce full-length proteins. As opposed to a typical gene therapy approach of targeting a single, unique mutation in a target disease, this small molecule strategy enables targeting an entire class of mutations across the rare disease landscape. The small molecule approach has the potential to address a range of different premature stop codons in a single gene since the ERSG compounds are targeted to the ribosomes. ELX-02, the Company’s lead investigational drug product candidate, is a small molecule designed to restore production of full-length functional proteins. ELX-02 is in clinical development for systemic administration for cystic fibrosis. ELX-02 is an investigational drug that has not been approved by any global regulatory body. The Company is also conducting investigational new drug (IND) enabling preclinical studies of ERSG compounds for autosomal dominant polycystic kidney disease (ADPKD) and in rare inherited retinal disorders (IRDs) by intravitreal administration with an initial focus on Usher Syndrome. The Company’s preclinical candidate pool consists of a library of novel ERSG drug candidates identified based on read-through potential and cytoplasmic ribosomal selectivity. The Company is headquartered in Waltham, Massachusetts, with additional offices in Morristown, New Jersey and Rehovot, Israel. The Company’s research and development strategy is to target rare or ultra-rare diseases where a high unmet medical need exists, a nonsense mutation-bearing patient population is established, preclinical read-through can be established in predictive personalized medicine models, and a defined path through Orphan Drug development, regulatory approval, patient access and commercialization is identified. The Company believes patient advocacy is an important element of patient focused drug development and seeks opportunities to collaborate with patient advocacy groups throughout the discovery and development process. The Company’s current clinical program for its lead investigational drug product candidate, ELX-02, includes Phase 2 studies in cystic fibrosis in Europe, Israel and the United States. On March 25, 2020, the Company announced that enrollment in its Phase 2 clinical trials for ELX-02 in cystic fibrosis had been temporarily paused in response to the COVID-19 pandemic in order to avoid unnecessary exposure in at-risk populations, to maintain the integrity of study data and to support global healthcare providers in their commitment to ensure patient safety. On June 17, 2020, the Company announced that enrollment in its Phase 2 clinical trial in cystic fibrosis has been resumed in Israel and Europe, and that its U.S. trial remains temporarily paused due to the COVID-19 pandemic. The extent and severity of the impact of the current global health crisis on the Company’s business and clinical trials will be determined largely by the ability of patients and prospective patients in its clinical trials to access trial sites, the ability of personnel from clinical research organizations (“CROs”) to administer the Company’s drug in accordance with trial protocols and the Company’s ability to monitor and communicate effectively with CROs, staff at clinical trial sites and principal investigators. In addition, the impact of the COVID-19 pandemic on the operations of the U.S. Food and Drug Administration and other health authorities may delay potential advancement of the Company’s product candidates. During 2019, the Company announced that the Cystic Fibrosis Foundation (the “CF Foundation”) is providing funding for a portion of the U.S. Phase 2 cystic fibrosis clinical trial and that it will form a joint program advisory group with the CF Foundation focused on the development of ELX-02 for cystic fibrosis. The Cystic Fibrosis Therapeutics Development Network (“TDN”) has sanctioned the Phase 2 study protocol, which is being conducted at TDN member sites. On August 4, 2020, the Company announced that the U.S. Food and Drug Administration (FDA) has granted the Company orphan drug designation for ELX-02 for the treatment of cystic fibrosis. The FDA’s Office of Orphan Drug Products grants orphan status to support the development of medicines for underserved patient populations, or rare disorders, that affect fewer than 200,000 people in the U.S. Orphan drug designation qualifies Eloxx for certain benefits, including seven years of market exclusivity upon regulatory approval (if received), exemption from FDA application fees, tax credits on qualified U.S. clinical trials and eligibility for grant funding opportunities that can be used for clinical trial costs. Liquidity The Company has a history of net losses and negative cash flows from operating activities since inception, and as of June 30, 2020, had an accumulated deficit of $(158.9) million. The Company expects to continue to incur net losses and use cash in its operations for the foreseeable future. To date, the Company has not generated revenue from the sale of any product or service and does not expect to generate significant revenue unless and until it obtains marketing approval for and commercializes one or more of its product candidates currently in development. Successful transition to profitable operations is dependent upon achieving a level of revenue adequate to support the Company’s cost structure. The Company has financed its operations primarily from the sale of equity securities and to a lesser extent, loans and grants. The Company may never achieve profitability, and unless and until it does, the Company will continue to need to raise additional capital to fund its operations. As discussed in Note 14, on February 24, 2020, the Company’s Board of Directors approved a leadership and organizational realignment, aimed at supporting the Company’s efforts to improve operating performance, and concentrate development efforts on the Company’s core programs. The Company believes that its cash, cash equivalents and marketable securities of $37.1 million at June 30, 2020 will enable it to meet anticipated cash needs required to maintain the Company’s current and planned operations .

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	2. Basis of Presentation and Significant Accounting Policies The Company has prepared the accompanying unaudited interim condensed consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASUs”) promulgated by the Financial Accounting Standards Board (“FASB”). The Company has reclassified certain items from the prior year’s condensed consolidated financial statements to conform to the current year’s presentation. The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the full year. These interim financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2019, and the notes thereto, which are included in the Company’s 2019 Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (the “SEC”) on March 6, 2020. The significant accounting policies used in the preparation of these condensed consolidated financial statements are consistent with those described in the Company’s audited financial statements as of and for the year ended December 31, 2019, and the notes thereto, in the Company’s 2019 Annual Report on Form 10-K, except as follows. Due to its adoption of ASU No. 2016-13 (further described below under the heading “Recent Accounting Pronouncements – Adopted” Marketable Securities The Company classifies all investment instruments with an original maturity date, when purchased, in excess of three months but less than one year as current marketable securities. Marketable securities are classified as available-for-sale and are carried at fair value. The Company periodically assesses its portfolio of securities to determine whether to record any estimated allowances for credit losses in the statement of operations. This assessment includes considering whether the Company intends to sell a security, whether it is more likely than not that the Company will have to sell a security before recovery of its amortized cost, and whether a decline in a security’s fair value below its amortized cost is credit-related or non-credit-related. The Company records non-credit-related unrealized gains and losses on available-for-sale securities in accumulated other comprehensive income, which is a separate component of stockholders’ equity on its consolidated balance sheet. Gains or losses realized upon sales of available-for-sale securities are recorded in other income. The cost of securities sold is based on the specific identification method. To date, the Company has recorded no allowances for credit losses, and no realized gains or losses upon sales of securities. Recent Accounting Pronouncements – Adopted In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	6 Months Ended
	Jun. 30, 2020
Prepaid And Other Current Assets [Abstract]
Prepaid Expenses and Other Current Assets	3. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets as of June 30, 2020 and December 31, 2019 consisted of the following (in thousands): June 30, 2020 December 31, 2019 Research and development $ 921 $ 448 Other 649 699 Insurance 229 217 VAT receivables 1 26 $ 1,800 $ 1,390

Property and Equipment

Property and Equipment	6 Months Ended
	Jun. 30, 2020
Property Plant And Equipment [Abstract]
Property and Equipment	4. Property and Equipment Property and equipment, net as of June 30, 2020 and December 31, 2019 consisted of the following (in thousands): June 30, 2020 December 31, 2019 Computers and software $ 124 $ 166 Office furniture and equipment 164 164 Leasehold improvements 158 158 446 488 Less: Accumulated depreciation (281 ) (287 ) Property and equipment, net $ 165 $ 201 Depreciation expense was $17 thousand and $17 thousand for the three months ended June 30, 2020 and 2019 and $36 thousand and $50 thousand for the six months ended June 30, 2020 and 2019, respectively.

Accrued Expenses

Accrued Expenses	6 Months Ended
	Jun. 30, 2020
Payables And Accruals [Abstract]
Accrued Expenses	5. Accrued Expenses Accrued expenses as of June 30, 2020 and December 31, 2019 consisted of the following (in thousands): June 30, 2020 December 31, 2019 Research and development expenses $ 936 $ 1,560 Payroll, bonus and other employee-related expenses 1,070 2,200 Restructuring 958 — Professional services 424 664 Other 34 137 Interest on debt 63 94 $ 3,485 $ 4,655

Debt

Debt	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Debt	6. Debt Term Loan On January 30, 2019, the Company entered into a Loan and Security Agreement (the “SVB Loan Agreement”) in the amount of $15.0 million with Silicon Valley Bank (“SVB”) and WestRiver Innovation Lending Fund VIII, L.P. (“WestRiver”, and together with SVB, the “Lenders”). Outstanding principal on the loan accrues interest at a floating rate equal to the greater of (i) 5.25% per annum and (ii) the sum of 2.5% plus the prime rate, as published in the Wall Street Journal. Interest payments are payable monthly following the funding of the loan. On June 30, 2020, the interest rate was 5.75%. The Company commenced making principal and interest payments on the outstanding balance of the loan on February 1, 2020, which is payable in 36 equal monthly installments. Amounts outstanding under the loan are due and payable on January 1, 2023. In conjunction with the initial loan advance, the Company issued warrants (the “Warrants”) to SVB and WestRiver to purchase an aggregate of 40,834 shares of the Company’s common stock at a warrant exercise price of $11.02 (subject to certain adjustments), which price was calculated using the 10-day average bid price of the Company’s common stock prior to the date of the SVB Loan Agreement. The Company may prepay the outstanding principal balance of the loans advanced by SVB in whole but not in part, subject to a prepayment fee ranging from 1% to 3% of any amount prepaid, depending upon when the prepayment occurs. The Company will also pay a final payment fee equal to 6% of the total loans advanced, due upon the earlier of maturity or termination of the SVB Loan Agreement. Under the terms of the SVB Loan Agreement, the Company granted first priority liens and security interests in substantially all of the Company’s assets (excluding all of its intellectual property, which is subject to a negative pledge) and a pledge by the Company of the shares of one of its wholly-owned subsidiaries as collateral for the obligations thereunder. The SVB Loan Agreement also contains representations and warranties by the Company and SVB and indemnification provisions in favor of SVB and customary covenants (including limitations on other indebtedness, liens, acquisitions, investments and dividends, but no financial covenants), and events of default (including payment defaults, breaches of covenants following any applicable cure period, a material impairment in the perfection or priority of SVB’s security interest in the collateral, and events relating to bankruptcy or insolvency). As of June 30, 2020, the carrying value of the outstanding loan consists of $12.9 million in principal less the unamortized debt discount of approximately $0.8 million. The debt issuance costs, the valuation of the Warrants, and the final maturity payment of $0.9 million, have been recorded as a debt discount which are being accreted to interest expense through the maturity date of the loan. Interest expense relating to the loan for the three months ended June 30, 2020 and 2019 was $0.3 million and $0.5 million, respectively, and for the six months ended June 30, 2020 and 2019 was $0.8 million and $0.7 million, respectively. Interest expense is calculated using the effective interest method and is inclusive of non-cash amortization of the debt discount. At June 30, 2020, the effective interest rate was 10.85%. PPP Loan In April 2020, the Company entered into a loan agreement with SVB under the U.S. Small Business Administration (the “SBA”) Paycheck Protection Program (the “PPP”) pursuant to the Coronavirus Aid, Relief and Economic Security Act of 2020 (the “CARES Act”) and received loan proceeds of $0.8 million (the “PPP Loan”). The Company expects to use the loan proceeds for payroll and other covered costs in accordance with the relevant terms and conditions of the CARES Act. The Company issued a promissory note for the PPP Loan with a maturity date of April 21, 2022 and an interest rate of 1.0% per annum. Monthly payments of principal and interest will be due beginning on November 21, 2020, although interest accrues from the issuance date. The Company may prepay the PPP Loan without penalty or premium, and the promissory note provides for customary events of default. A PPP loan may be partially or entirely forgiven based on employee retention for the 24-week period starting on the loan date through September 2020, and the use of loan proceeds for payroll or other specified costs during the same period. Forgiveness is also based on the employer maintaining or restoring headcount and maintaining salary levels. Forgiveness is reduced if headcount declines or if salaries decrease. Any loan forgiveness will be made subject to SVB approval in accordance with SBA requirements. The Company’s scheduled future principal payments for the long-term debt are as follows (in thousands): June 30, 2020 Remainder of 2020 $ 2,589 2021 5,531 2022 5,177 2023 417 Total future principal payments 13,714 Less: unamortized discount (761 ) Carrying value of long-term debt 12,953 Less: current portion (5,149 ) Add: Final fee due at maturity in 2023 900 Long-term portion $ 8,704

Legal and Other Contingencies

Legal and Other Contingencies	6 Months Ended
	Jun. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Legal and Other Contingencies	7. Legal and Other Contingencies From time to time, the Company may become involved in various lawsuits and legal proceedings, which arise in the ordinary course of business. The Company is currently unaware of any material pending legal proceedings to which it is a party or of which its property is the subject. However, the Company may at times in the future become involved in litigation in the ordinary course of business, which may include actions related to or based on its intellectual property and its use, customer claims, product liability claims, employment practices and employee complaints and other events arising out of its operations. When appropriate in management’s estimation, the Company will record adequate reserves in its financial statements for pending litigation. Litigation is subject to inherent uncertainties, and an adverse result in any such matters could adversely impact its reputation, operations, and its financial operating results or overall financial condition. Additionally, any litigation to which the Company may become subject could also require significant involvement of its senior management and may divert management’s attention from the Company’s business and operations. The Company accounts for its contingent liabilities in accordance with ASC Topic 450, “Contingencies”. A provision is recorded when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. With respect to legal matters, provisions are reviewed and adjusted to reflect the impact of negotiations, estimated settlements, legal rulings, advice of legal counsel and other information and events pertaining to a particular matter. For the periods ended June 30, 2020 and 2019, the Company was not a party to any litigation that is reasonably possible to have a material adverse effect on the Company’s business, financial position, results of operations or cash flows. Legal costs incurred in connection with loss contingencies are expensed as incurred.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Stockholders' Equity	8. Stockholders’ Equity Warrants In connection with the January 2019 issuance of debt, the Company granted warrants to purchase 40,834 shares of common stock and recorded a charge in additional paid-in-capital in the amount of $0.4 million reflecting the fair value of the warrants on the date of issuance. Transactions related to warrants to purchase the Company’s common stock during the six months ended June 30, 2020, were as follows: Shares Weighted average exercise price Weighted average remaining contractual life (years) Warrants outstanding at December 31, 2019 323,894 $ 4.32 3.74 Granted — Exercised — Forfeited — Warrants outstanding at June 30, 2020 323,894 $ 4.32 3.24 Warrants exercisable at June 30, 2020 323,894 $ 4.32 3.24

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	9. Stock-Based Compensation Summary of Option Activity Transactions related to stock options awarded to employees and directors during the six months ended June 30, 2020 were as follows: Shares Weighted average exercise price Weighted average remaining contractual life (years) Aggregate intrinsic value Options outstanding at December 31, 2019 4,737,670 $ 11.17 8.54 $ 3,629,073 Granted 1,360,910 3.54 Exercised (10,636 ) 6.00 Forfeited (1,135,714 ) 10.08 Options outstanding at June 30, 2020 4,952,230 $ 10.18 6.97 $ 857,311 Options exercisable at June 30, 2020 2,497,570 $ 12.72 4.67 $ 772,603 The aggregate intrinsic value represents the total intrinsic value (the difference between the fair value of the Company’s common stock as of June 30, 2020 and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their options on June 30, 2020. This amount is impacted by changes in the fair value of the Company’s common stock. Summary of Restricted Stock Unit Activity Transactions related to restricted stock units awarded to employees during the six months ended June 30, 2020 were as follows: Shares Weighted average grant date fair value per share Unvested at December 31, 2019 463,945 $ 9.45 Granted 300,000 3.59 Vested (129,801 ) 9.88 Forfeited (266,977 ) 8.65 Unvested at June 30, 2020 367,167 $ 5.09 Stock-based Compensation Expense Stock-based compensation relates to stock options granted to employees, non-employee directors and non-employees, time-based restricted stock units granted to employees and performance-based stock options and restricted stock units granted to an employee. On February 24, 2020, the Company’s Board of Directors approved a leadership and organizational realignment, which accelerated the vesting of certain awards, resulting in additional stock-based compensation of $2.1 million recorded in restructuring charges. Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Research and development $ 262 $ 744 $ 481 $ 1,269 General and administrative 1,714 2,272 3,366 4,405 Restructuring charges - — 2,124 — Total stock-based compensation expense $ 1,976 $ 3,016 $ 5,971 $ 5,674

Marketable Securities

Marketable Securities	6 Months Ended
	Jun. 30, 2020
Investments Debt And Equity Securities [Abstract]
Marketable Securities	10. Marketable Securities Below is a summary of cash, cash equivalents and marketable securities at June 30, 2020 (in thousands): Amortized Unrealized Unrealized Fair Cost Gains Losses Value Cash and cash equivalents $ 30,347 $ — $ — $ 30,347 Marketable securities - U.S. treasuries 6,756 13 — 6,769 Total cash, cash equivalents and marketable securities $ 37,103 $ 13 $ — $ 37,116 Below is a summary of cash, cash equivalents and marketable securities at December 31, 2019 (in thousands): Amortized Unrealized Unrealized Fair Cost Gains Losses Value Cash and cash equivalents $ 22,493 $ — $ — $ 22,493 Marketable securities - U.S. treasuries 33,765 19 (1 ) 33,783 Total cash, cash equivalents and marketable securities $ 56,258 $ 19 $ (1 ) $ 56,276 As of June 30, 2020, and December 31, 2019 no credit losses were identified related to the cash equivalents or marketable securities.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	11. Fair Value of Financial Instruments At June 30, 2020 and December 31, 2019, the Company’s financial assets valued based on Level 1 inputs consisted of cash, cash equivalents and marketable securities (U.S. treasuries). During the three and six months ended June 30, 2020, the Company did not have any transfers of financial assets between Level 2 and 3. Some assets and liabilities are required to be recorded at fair value on a recurring basis, while other assets and liabilities are recorded at fair value on a nonrecurring basis. The carrying amounts of current financial instruments, which include accounts payable, accrued expenses, lease obligation liability and debt, approximate their fair values due to the short-term nature of these instruments.

Other Expense (Income), Net

Other Expense (Income), Net	6 Months Ended
	Jun. 30, 2020
Other Income And Expenses [Abstract]
Other Expense (Income), Net	12. Other Expense (Income), Net Other expense (income), net consisted of the following (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Interest and other income $ (69 ) $ (206 ) $ (313 ) $ (494 ) Foreign currency exchange losses 12 (8 ) 22 (31 ) Investment income, net 11 (130 ) 9 (133 ) Interest and other expense 347 482 762 736 Total other expense (income), net $ 301 $ 138 $ 480 $ 78

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Net Loss Per Share	13. Net Loss Per Share The loss and the weighted average number of shares used in computing basic and diluted net loss per share for the periods, are as follows (amounts in thousands, except share and per share data): Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Numerator: Net loss $ (7,887 ) $ (14,449 ) $ (21,833 ) $ (26,366 ) Denominator: Weighted average number of shares of common stock used in computing net loss per share, basic and diluted 40,129,304 36,278,567 40,101,789 36,098,171 Net loss per share, basic and diluted $ (0.20 ) $ (0.40 ) $ (0.54 ) $ (0.73 ) The following potentially dilutive securities have been excluded from the computation of diluted weighted average shares outstanding as their effect would be anti-dilutive: Six Months Ended June 30, 2020 2019 Options to purchase common stock 4,952,230 4,238,027 Restricted stock units 367,167 552,512 Warrants 323,894 323,894 Total potential common stock equivalents 5,643,291 5,114,433

Restructuring

Restructuring	6 Months Ended
	Jun. 30, 2020
Restructuring And Related Activities [Abstract]
Restructuring	14. Restructuring On February 24, 2020, the Company’s Board of Directors approved a leadership and organizational realignment aimed at supporting its efforts to improve operating performance and concentrate development efforts on its core programs. The organizational realignment reduced managerial layers and consolidated roles across the organization, resulting in the elimination of 13 full-time positions during the first quarter of 2020. This resulted in a one-time charge of $4.0 million, including $2.1 million in stock-based compensation expense, with the severance portion being paid out over a one-year period . The accrued charges and associated payments that occurred for the six months ended June 30, 2020 , are as follows (amounts in thousands): Beginning Balance Additions Deductions Ending Balance Severance and related costs $ — $ 1,705 $ (747 ) $ 958 Contract termination costs — 165 (165 ) — Total restructuring charges $ — $ 1,870 $ (912 ) $ 958

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Marketable Securities	Marketable Securities The Company classifies all investment instruments with an original maturity date, when purchased, in excess of three months but less than one year as current marketable securities. Marketable securities are classified as available-for-sale and are carried at fair value. The Company periodically assesses its portfolio of securities to determine whether to record any estimated allowances for credit losses in the statement of operations. This assessment includes considering whether the Company intends to sell a security, whether it is more likely than not that the Company will have to sell a security before recovery of its amortized cost, and whether a decline in a security’s fair value below its amortized cost is credit-related or non-credit-related. The Company records non-credit-related unrealized gains and losses on available-for-sale securities in accumulated other comprehensive income, which is a separate component of stockholders’ equity on its consolidated balance sheet. Gains or losses realized upon sales of available-for-sale securities are recorded in other income. The cost of securities sold is based on the specific identification method. To date, the Company has recorded no allowances for credit losses, and no realized gains or losses upon sales of securities.
Recent Accounting Pronouncements	Recent Accounting Pronouncements – Adopted In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	6 Months Ended
	Jun. 30, 2020
Prepaid And Other Current Assets [Abstract]
Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets as of June 30, 2020 and December 31, 2019 consisted of the following (in thousands): June 30, 2020 December 31, 2019 Research and development $ 921 $ 448 Other 649 699 Insurance 229 217 VAT receivables 1 26 $ 1,800 $ 1,390

Property and Equipment (Tables)

Property and Equipment (Tables)	6 Months Ended
	Jun. 30, 2020
Property Plant And Equipment [Abstract]
Property and equipment, net	Property and equipment, net as of June 30, 2020 and December 31, 2019 consisted of the following (in thousands): June 30, 2020 December 31, 2019 Computers and software $ 124 $ 166 Office furniture and equipment 164 164 Leasehold improvements 158 158 446 488 Less: Accumulated depreciation (281 ) (287 ) Property and equipment, net $ 165 $ 201

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Jun. 30, 2020
Payables And Accruals [Abstract]
Accrued expenses	Accrued expenses as of June 30, 2020 and December 31, 2019 consisted of the following (in thousands): June 30, 2020 December 31, 2019 Research and development expenses $ 936 $ 1,560 Payroll, bonus and other employee-related expenses 1,070 2,200 Restructuring 958 — Professional services 424 664 Other 34 137 Interest on debt 63 94 $ 3,485 $ 4,655

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Schedule of Future Principal Payments for Long-Term Debt	The Company’s scheduled future principal payments for the long-term debt are as follows (in thousands): June 30, 2020 Remainder of 2020 $ 2,589 2021 5,531 2022 5,177 2023 417 Total future principal payments 13,714 Less: unamortized discount (761 ) Carrying value of long-term debt 12,953 Less: current portion (5,149 ) Add: Final fee due at maturity in 2023 900 Long-term portion $ 8,704

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Summary of Warrants Outstanding	Transactions related to warrants to purchase the Company’s common stock during the six months ended June 30, 2020, were as follows: Shares Weighted average exercise price Weighted average remaining contractual life (years) Warrants outstanding at December 31, 2019 323,894 $ 4.32 3.74 Granted — Exercised — Forfeited — Warrants outstanding at June 30, 2020 323,894 $ 4.32 3.24 Warrants exercisable at June 30, 2020 323,894 $ 4.32 3.24

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Transactions Related to Stock Options Awarded to Employees and Directors	Transactions related to stock options awarded to employees and directors during the six months ended June 30, 2020 were as follows: Shares Weighted average exercise price Weighted average remaining contractual life (years) Aggregate intrinsic value Options outstanding at December 31, 2019 4,737,670 $ 11.17 8.54 $ 3,629,073 Granted 1,360,910 3.54 Exercised (10,636 ) 6.00 Forfeited (1,135,714 ) 10.08 Options outstanding at June 30, 2020 4,952,230 $ 10.18 6.97 $ 857,311 Options exercisable at June 30, 2020 2,497,570 $ 12.72 4.67 $ 772,603
Transactions Related to Restricted Stock Units Awarded to Employees	Transactions related to restricted stock units awarded to employees during the six months ended June 30, 2020 were as follows: Shares Weighted average grant date fair value per share Unvested at December 31, 2019 463,945 $ 9.45 Granted 300,000 3.59 Vested (129,801 ) 9.88 Forfeited (266,977 ) 8.65 Unvested at June 30, 2020 367,167 $ 5.09
Summary of Allocated Stock-based Compensation Expense	The total equity-based compensation expense related to all of the Company’s equity-based awards was recognized as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Research and development $ 262 $ 744 $ 481 $ 1,269 General and administrative 1,714 2,272 3,366 4,405 Restructuring charges - — 2,124 — Total stock-based compensation expense $ 1,976 $ 3,016 $ 5,971 $ 5,674

Marketable Securities (Tables)

Marketable Securities (Tables)	6 Months Ended
	Jun. 30, 2020
Investments Debt And Equity Securities [Abstract]
Summary of Cash, Cash Equivalents and Marketable Securities	Below is a summary of cash, cash equivalents and marketable securities at June 30, 2020 (in thousands): Amortized Unrealized Unrealized Fair Cost Gains Losses Value Cash and cash equivalents $ 30,347 $ — $ — $ 30,347 Marketable securities - U.S. treasuries 6,756 13 — 6,769 Total cash, cash equivalents and marketable securities $ 37,103 $ 13 $ — $ 37,116 Below is a summary of cash, cash equivalents and marketable securities at December 31, 2019 (in thousands): Amortized Unrealized Unrealized Fair Cost Gains Losses Value Cash and cash equivalents $ 22,493 $ — $ — $ 22,493 Marketable securities - U.S. treasuries 33,765 19 (1 ) 33,783 Total cash, cash equivalents and marketable securities $ 56,258 $ 19 $ (1 ) $ 56,276

Other Expense (Income), Net (Ta

Other Expense (Income), Net (Tables)	6 Months Ended
	Jun. 30, 2020
Other Income And Expenses [Abstract]
Schedule of Other Expense (Income), Net	Other expense (income), net consisted of the following (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Interest and other income $ (69 ) $ (206 ) $ (313 ) $ (494 ) Foreign currency exchange losses 12 (8 ) 22 (31 ) Investment income, net 11 (130 ) 9 (133 ) Interest and other expense 347 482 762 736 Total other expense (income), net $ 301 $ 138 $ 480 $ 78

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Schedule of Loss and Weighted Average Number of Shares Used in Computing Basic and Diluted Net Loss Per Share	The loss and the weighted average number of shares used in computing basic and diluted net loss per share for the periods, are as follows (amounts in thousands, except share and per share data): Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Numerator: Net loss $ (7,887 ) $ (14,449 ) $ (21,833 ) $ (26,366 ) Denominator: Weighted average number of shares of common stock used in computing net loss per share, basic and diluted 40,129,304 36,278,567 40,101,789 36,098,171 Net loss per share, basic and diluted $ (0.20 ) $ (0.40 ) $ (0.54 ) $ (0.73 )
Potentially Dilutive Securities Excluded from Computation of Diluted Weighted Average Shares Outstanding	The following potentially dilutive securities have been excluded from the computation of diluted weighted average shares outstanding as their effect would be anti-dilutive: Six Months Ended June 30, 2020 2019 Options to purchase common stock 4,952,230 4,238,027 Restricted stock units 367,167 552,512 Warrants 323,894 323,894 Total potential common stock equivalents 5,643,291 5,114,433

Restructuring (Tables)

Restructuring (Tables)	6 Months Ended
	Jun. 30, 2020
Restructuring And Related Activities [Abstract]
Summary of Accrued Charges and Associated Payments	The accrued charges and associated payments that occurred for the six months ended June 30, 2020 , are as follows (amounts in thousands): Beginning Balance Additions Deductions Ending Balance Severance and related costs $ — $ 1,705 $ (747 ) $ 958 Contract termination costs — 165 (165 ) — Total restructuring charges $ — $ 1,870 $ (912 ) $ 958

Nature of the Business - Additi

Nature of the Business - Additional Information (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2020USD ($)Disease	Dec. 31, 2019USD ($)
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Number of rare diseases | Disease	1,800
Accumulated deficit	$ (158,852)	$ (137,019)
Cash, cash equivalents and marketable securities	$ 37,116	$ 56,276

Basis of Presentation and Sig_3

Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Accounting Policies [Line Items]
Available-for-sale securities, allowance for credit losses	$ 0	$ 0
Realized gains or losses on the sale of available-for-sale securities	$ 0
ASU 2016-13 [Member]
Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2020
Change in accounting principle, accounting standards update, immaterial effect	true
ASU 2018-13 [Member]
Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2020
Change in accounting principle, accounting standards update, immaterial effect	true

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Research and development	$ 921	$ 448
Other	649	699
Insurance	229	217
VAT receivables	1	26
Total	$ 1,800	$ 1,390

Property and Equipment - Proper

Property and Equipment - Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Cost	$ 446	$ 488
Less: Accumulated depreciation	(281)	(287)
Property and equipment, net	165	201
Computers and software [Member]
Property, Plant and Equipment [Line Items]
Cost	124	166
Office furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	164	164
Leasehold improvement [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 158	$ 158

Property and Equipment - Additi

Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Property Plant And Equipment [Abstract]
Depreciation expenses	$ 17	$ 17	$ 36	$ 50

Accrued Expenses - Accrued Expe

Accrued Expenses - Accrued Expenses (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Research and development expenses	$ 936	$ 1,560
Payroll, bonus and other employee-related expenses	1,070	2,200
Restructuring	958
Professional services	424	664
Other	34	137
Interest on debt	63	94
Total	$ 3,485	$ 4,655

Debt - Additional Information (

Debt - Additional Information (Detail) $ / shares in Units, $ in Thousands	Jan. 30, 2019USD ($)Installment$ / sharesshares	Apr. 30, 2020USD ($)	Jun. 30, 2020USD ($)$ / sharesshares	Jun. 30, 2019USD ($)	Jun. 30, 2020USD ($)$ / sharesshares	Jun. 30, 2019USD ($)	Dec. 31, 2019$ / shares
Debt Instrument [Line Items]
Aggregate principal amount of initial loan advance			$ 12,953		$ 12,953
Warrants issued to purchase shares of common stock | shares			40,834		40,834
Warrant exercise price | $ / shares			$ 4.32		$ 4.32		$ 4.32
Loan, principal outstanding			$ 13,714		$ 13,714
Loan, unamortized debt discount			761		761
Loan, final maturity payment			$ 900		$ 900
Loan Agreement [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate terms	Outstanding principal on the loan accrues interest at a floating rate equal to the greater of (i) 5.25% per annum and (ii) the sum of 2.5% plus the prime rate, as published in the Wall Street Journal. Interest payments are payable monthly following the funding of the loan.
Debt instrument, payment terms	The Company commenced making principal and interest payments on the outstanding balance of the loan on February 1, 2020, which is payable in 36 equal monthly installments.
Loan, floating interest rate	5.25%
Loan, interest rate			5.75%		5.75%
Loan, frequency of periodic payment	monthly
Loan, number of repayment installments | Installment	36
Loan, periodic principal and interest payment commencement date	Feb. 1, 2020
Loan, maturity date	Jan. 1, 2023
Warrant exercise price | $ / shares	$ 11.02
Common stock average closing bid price number of trading days	10 days
Loan, prepayment fee percentage	6.00%
Loan, principal outstanding			$ 12,900		$ 12,900
Loan, unamortized debt discount			800		800
Loan, interest expense			$ 300	$ 500	$ 800	$ 700
Loan, effective interest rate			10.85%		10.85%
Loan, final maturity payment			$ 900		$ 900
Loan Agreement [Member] | Minimum [Member]
Debt Instrument [Line Items]
Loan, prepayment fee percentage	1.00%
Loan Agreement [Member] | Maximum [Member]
Debt Instrument [Line Items]
Loan, prepayment fee percentage	3.00%
Loan Agreement [Member] | Prime Rate [Member]
Debt Instrument [Line Items]
Loan, floating interest rate	2.50%
Loan Agreement [Member] | Initial Loan [Member]
Debt Instrument [Line Items]
Aggregate principal amount of initial loan advance	$ 15,000
Warrants issued to purchase shares of common stock | shares	40,834
Loan Agreement [Member] | PPP Loan [Member]
Debt Instrument [Line Items]
Loan, periodic principal and interest payment commencement date		Nov. 21, 2020
Loan, maturity date		Apr. 21, 2022
PPP Loan proceeds received		$ 800
Promissory note interest rate		1.00%

Debt - Schedule of Future Princ

Debt - Schedule of Future Principal Payments for Long-Term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Remainder of 2020	$ 2,589
2021	5,531
2022	5,177
2023	417
Total future principal payments	13,714
Less: unamortized discount	(761)
Carrying value of long-term debt	12,953
Less: current portion	(5,149)	$ (4,336)
Add: Final fee due at maturity in 2023	900
Long-term portion	$ 8,704	$ 10,502

Stockholder's Equity - Addition

Stockholder's Equity - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2019	Jun. 30, 2020
Stockholders Equity [Abstract]
Number of common stock in warrant		40,834
Adjustment to additional paid-in-capital by warrants issued	$ 421	$ 400

Stockholder's Equity - Schedule

Stockholder's Equity - Schedule of Transaction Related to Warrants to Purchase Common Stock (Detail) - $ / shares	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Stockholders Equity [Abstract]
Warrants outstanding beginning balance, Shares	323,894
Warrants outstanding ending balance, Shares	323,894	323,894
Warrants exercisable, Shares	323,894
Warrants outstanding beginning balance, Weighted average exercise price	$ 4.32
Warrants outstanding ending balance,Weighted average exercise price	4.32	$ 4.32
Warrants exercisable, Weighted average exercise price	$ 4.32
Warrants outstanding, Weighted average remaining contractual life	3 years 2 months 26 days	3 years 8 months 26 days
Warrants exercisable, Weighted average remaining contractual life	3 years 2 months 26 days

Stock-based Compensation - Tran

Stock-based Compensation - Transactions Related to Stock Options Awarded to Employees and Directors (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Amount
Options outstanding at December 31, 2019	4,737,670
Granted	1,360,910
Exercised	(10,636)
Forfeited	(1,135,714)
Options outstanding at June 30, 2020	4,952,230	4,737,670
Options exercisable at June 30, 2020	2,497,570
Weighted average exercise price
Options outstanding at December 31, 2019	$ 11.17
Granted	3.54
Exercised	6
Forfeited	10.08
Options outstanding at June 30, 2020	10.18	$ 11.17
Options exercisable at June 30, 2020	$ 12.72
Weighted average remaining contractual life
Options outstanding	6 years 11 months 19 days	8 years 6 months 14 days
Options exercisable	4 years 8 months 1 day
Aggregate intrinsic value
Options outstanding	$ 857,311	$ 3,629,073
Options exercisable	$ 772,603

Stock-based Compensation - Tr_2

Stock-based Compensation - Transactions Related to Restricted Stock Units Awarded to Employees (Detail) - Restricted Stock Units [Member]	6 Months Ended
	Jun. 30, 2020$ / sharesshares
Amount
Unvested at December 31, 2019 | shares	463,945
Granted | shares	300,000
Vested | shares	(129,801)
Forfeited | shares	(266,977)
Unvested at June 30, 2020 | shares	367,167
Weighted average grant date fair value price
Unvested at December 31, 2019 | $ / shares	$ 9.45
Granted | $ / shares	3.59
Vested | $ / shares	9.88
Forfeited | $ / shares	8.65
Unvested at June 30, 2020 | $ / shares	$ 5.09

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Detail) - USD ($) $ in Thousands	Feb. 24, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional stock-based compensation		$ 1,976	$ 3,016	$ 5,971	$ 5,674
Restructuring Charges [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional stock-based compensation	$ 2,100			$ 2,124

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Allocated Stock-based Compensation Expense (Detail) - USD ($) $ in Thousands	Feb. 24, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense		$ 1,976	$ 3,016	$ 5,971	$ 5,674
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense		262	744	481	1,269
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense		$ 1,714	$ 2,272	3,366	$ 4,405
Restructuring Charges [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 2,100			$ 2,124

Marketable Securities - Summary

Marketable Securities - Summary of Cash, Cash Equivalents and Marketable Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	$ 30,347	$ 22,493	$ 49,326
Cash and cash equivalents, Fair Value	30,347	22,493
Total cash, cash equivalents and marketable securities, Amortized Cost	37,103	56,258
Total cash, cash equivalents and marketable securities, Unrealized Gains	13	19
Total cash, cash equivalents and marketable securities, Unrealized Losses		(1)
Total cash, cash equivalents and marketable securities, Fair Value	37,116	56,276
U.S. treasuries [Member]
Schedule Of Available For Sale Securities [Line Items]
Marketable securities, Amortized Cost	6,756	33,765
Marketable securities, Unrealized Gains	13	19
Marketable securities, Unrealized Losses		(1)
Marketable securities, Fair Value	$ 6,769	$ 33,783

Marketable Securities - Additio

Marketable Securities - Additional Information (Detail) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Investments Debt And Equity Securities [Abstract]
Credit losses related to the cash equivalents or marketable securities	$ 0	$ 0

Fair Value of Financial Instr_2

Fair Value of Financial Instruments - Additional Information (Detail)	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Transfers of financial assets between level 2 and level 3	the Company did not have any transfers of financial assets between Level 2 and 3	the Company did not have any transfers of financial assets between Level 2 and 3

Other Expense (Income), Net - S

Other Expense (Income), Net - Schedule of Other Expense (Income), Net (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other Income And Expenses [Abstract]
Interest and other income	$ (69)	$ (206)	$ (313)	$ (494)
Foreign currency exchange losses	12	(8)	22	(31)
Investment income, net	11	(130)	9	(133)
Interest and other expense	347	482	762	736
Total other expense (income), net	$ 301	$ 138	$ 480	$ 78

Net Loss Per Share - Weighted A

Net Loss Per Share - Weighted Average Number of Shares Used in Computing Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator:
Net loss	$ (7,887)	$ (13,946)	$ (14,449)	$ (11,917)	$ (21,833)	$ (26,366)
Denominator:
Weighted average number of shares of common stock used in computing net loss per share, basic and diluted	40,129,304		36,278,567		40,101,789	36,098,171
Net loss per share, basic and diluted	$ (0.20)		$ (0.40)		$ (0.54)	$ (0.73)

Net Loss Per Share - Potentiall

Net Loss Per Share - Potentially Dilutive Securities Excluded from Computation of Diluted Weighted Average Shares Outstanding (Detail) - shares	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential common stock equivalents	5,643,291	5,114,433
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential common stock equivalents	4,952,230	4,238,027
Restricted Stock Units [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential common stock equivalents	367,167	552,512
Warrants [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential common stock equivalents	323,894	323,894

Restructuring - Additional Info

Restructuring - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)Employee
Restructuring And Related Activities [Abstract]
Elimination of managerial full time positions | Employee	13
Severance costs, one-time charge	$ 4
Severance costs, stock-based compensation expense	$ 2.1
Restructuring and related costs, severance cost payment period	1 year

Restructuring - Summary of Accr

Restructuring - Summary of Accrued Charges and Associated Payments (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2020USD ($)
Restructuring Cost And Reserve [Line Items]
Additions	$ 1,870
Deductions	(912)
Ending Balance	958
Severance and Related Costs [Member]
Restructuring Cost And Reserve [Line Items]
Additions	1,705
Deductions	(747)
Ending Balance	958
Contract Termination Costs [Member]
Restructuring Cost And Reserve [Line Items]
Additions	165
Deductions	$ (165)