Concert Pharmaceuticals (CNCE) 10-Q 9 Nov 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Nov. 05, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-36310
Entity Registrant Name	CONCERT PHARMACEUTICALS, INC.
Entity Incorporation, State	DE
Entity Tax Identification Number	20-4839882
Entity Address, Street	65 Hayden Avenue
Entity Address, Suite	Suite 3000N
Entity Address, City	Lexington
Entity Address, State	MA
Entity Address, Postal Zip Code	02421
City Area Code	781
Local Phone Number	860-0045
Title of each class	Common Stock, par value $0.001 per share
Trading Symbol(s)	CNCE
Name of each exchange on which registered	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		34,659,815
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001367920
Current Fiscal Year End Date	--12-31

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 103,664	$ 77,202
Investments, available for sale	0	52,766
Marketable equity securities	2,559	1,969
Interest receivable	0	145
Deferred offering costs	42	0
Accounts receivable	476	686
Income taxes receivable, current	0	2,346
Prepaid expenses and other current assets	6,167	7,610
Total current assets	112,908	142,724
Property and equipment, net	5,441	6,363
Restricted cash	1,157	1,157
Other assets	10	51
Operating lease right-of-use asset, long-term	8,692	8,968
Total assets	128,208	159,263
Current liabilities:
Accounts payable	584	230
Accrued expenses and other liabilities	10,341	9,017
Lease liability, current portion	1,096	931
Total current liabilities	12,021	10,178
Accrued expenses, net of current portion	62	108
Deferred revenue, long-term	2,750	2,750
Lease liability, net of current portion	14,213	15,065
Total liabilities	29,046	28,101
Commitments (Note 11)
Stockholders’ equity:
Preferred stock, $0.001 par value per share; 5,000,000 shares authorized; no shares issued and outstanding as of September 30, 2021 and December 31, 2020, respectively	0	0
Common stock, $0.001 par value per share; 100,000,000 shares authorized; 32,607,416 and 32,062,799 shares issued and 32,406,815 and 31,862,198 shares outstanding as of September 30, 2021 and December 31, 2020, respectively	31	31
Additional paid-in capital	412,576	400,636
Accumulated other comprehensive loss	(76)	(58)
Accumulated deficit	(313,369)	(269,447)
Total stockholders’ equity	99,162	131,162
Total liabilities and stockholders’ equity	$ 128,208	$ 159,263

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	32,607,416	32,062,799
Common stock, shares outstanding (in shares)	32,406,815	31,862,198

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue:
Total revenue	$ 543	$ 1,501	$ 32,565	$ 7,895
Operating expenses:
Research and development	21,876	16,347	60,560	45,121
General and administrative	5,462	4,514	16,561	13,917
Total operating expenses	27,338	20,861	77,121	59,038
Loss from operations	(26,795)	(19,360)	(44,556)	(51,143)
Investment income	4	183	44	1,101
Unrealized gain (loss) on marketable equity securities	113	269	590	(2,419)
Loss before income taxes	(26,678)	(18,908)	(43,922)	(52,461)
Income tax benefit	0	0	0	(85)
Net loss	(26,678)	(18,908)	(43,922)	(52,376)
Other comprehensive (loss) income:
Unrealized (loss) gain on investments, available for sale	0	(141)	(18)	66
Comprehensive loss	$ (26,678)	$ (19,049)	$ (43,940)	$ (52,310)
Earnings Per Share [Abstract]
Net loss per share applicable to common stockholders - basic (in dollars per share)	$ (0.78)	$ (0.60)	$ (1.29)	$ (1.71)
Net loss per share applicable to common stockholders - diluted (in dollars per share)	$ (0.78)	$ (0.60)	$ (1.29)	$ (1.71)
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted average number of shares outstanding, basic (in shares)	34,090	31,547	33,987	30,707
Weighted average number of shares outstanding, diluted (in shares)	34,090	31,547	33,987	30,707
License and research and development revenue
Revenue:
Total revenue	$ 4	$ 1,501	$ 26	$ 7,895
Other revenue
Revenue:
Total revenue	$ 539	$ 0	$ 32,539	$ 0

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	IPO	Common Stock	Common StockIPO	In Treasury	Additional paid-in capital	Additional paid-in capitalIPO	Accumulated other comprehensive (loss) income	Accumulated deficit
Beginning balance at Dec. 31, 2019	$ 101,457		$ 24			$ 296,145		$ (31)	$ (194,681)
Beginning balance (in shares) at Dec. 31, 2019			24,066,000		200,000
Increase (Decrease) in Stockholders' Equity
Exercise of stock options	435					435
Exercise of stock options (in shares)			51,000
Unrealized gain (loss) on short-term investments	523							523
Stock-based compensation expense	2,477					2,477
New shares issued		$ 70,064		$ 5			$ 70,059
New shares issued (in shares)				5,735,000
Net loss	(20,477)								(20,477)
Ending balance at Mar. 31, 2020	154,479		$ 29			369,116		492	(215,158)
Ending balance (in shares) at Mar. 31, 2020			29,852,000		200,000
Beginning balance at Dec. 31, 2019	101,457		$ 24			296,145		(31)	(194,681)
Beginning balance (in shares) at Dec. 31, 2019			24,066,000		200,000
Increase (Decrease) in Stockholders' Equity
Unrealized gain (loss) on short-term investments	66
Net loss	(52,376)
Ending balance at Sep. 30, 2020	127,944		$ 29			374,937		35	(247,057)
Ending balance (in shares) at Sep. 30, 2020			30,019,000		200,000
Beginning balance at Mar. 31, 2020	154,479		$ 29			369,116		492	(215,158)
Beginning balance (in shares) at Mar. 31, 2020			29,852,000		200,000
Increase (Decrease) in Stockholders' Equity
Exercise of stock options	109					109
Exercise of stock options (in shares)			27,000
Unrealized gain (loss) on short-term investments	(316)							(316)
Stock-based compensation expense	2,804					2,804
Net loss	(12,991)								(12,991)
Ending balance at Jun. 30, 2020	144,085		$ 29			372,029		176	(228,149)
Ending balance (in shares) at Jun. 30, 2020			29,879,000		200,000
Increase (Decrease) in Stockholders' Equity
Exercise of stock options	13					13
Exercise of stock options (in shares)			4,000
Release of restricted stock units (in shares)			136,000
Unrealized gain (loss) on short-term investments	(141)							(141)
Stock-based compensation expense	2,895					2,895
Net loss	(18,908)								(18,908)
Ending balance at Sep. 30, 2020	127,944		$ 29			374,937		35	(247,057)
Ending balance (in shares) at Sep. 30, 2020			30,019,000		200,000
Beginning balance at Dec. 31, 2020	131,162		$ 31			400,636		(58)	(269,447)
Beginning balance (in shares) at Dec. 31, 2020			32,063,000		200,000
Increase (Decrease) in Stockholders' Equity
Exercise of stock options	89					89
Exercise of stock options (in shares)			10,000
Release of restricted stock units (in shares)			136,000
Unrealized gain (loss) on short-term investments	(16)							(16)
Stock-based compensation expense	3,431					3,431
New shares issued	2,042					2,042
New shares issued (in shares)			165,000
Net loss	(22,669)								(22,669)
Ending balance at Mar. 31, 2021	114,039		$ 31			406,198		(74)	(292,116)
Ending balance (in shares) at Mar. 31, 2021			32,374,000		200,000
Beginning balance at Dec. 31, 2020	$ 131,162		$ 31			400,636		(58)	(269,447)
Beginning balance (in shares) at Dec. 31, 2020			32,063,000		200,000
Increase (Decrease) in Stockholders' Equity
Exercise of stock options (in shares)	10,130
Unrealized gain (loss) on short-term investments	$ (18)
Net loss	(43,922)
Ending balance at Sep. 30, 2021	99,162		$ 31			412,576		(76)	(313,369)
Ending balance (in shares) at Sep. 30, 2021			32,607,000		200,000
Beginning balance at Mar. 31, 2021	114,039		$ 31			406,198		(74)	(292,116)
Beginning balance (in shares) at Mar. 31, 2021			32,374,000		200,000
Increase (Decrease) in Stockholders' Equity
Unrealized gain (loss) on short-term investments	(2)							(2)
Stock-based compensation expense	3,254					3,254
Net loss	5,425								5,425
Ending balance at Jun. 30, 2021	122,716		$ 31			409,452		(76)	(286,691)
Ending balance (in shares) at Jun. 30, 2021			32,374,000		200,000
Increase (Decrease) in Stockholders' Equity
Release of restricted stock units (in shares)			233,000
Unrealized gain (loss) on short-term investments	0
Stock-based compensation expense	3,124					3,124
Net loss	(26,678)
Ending balance at Sep. 30, 2021	$ 99,162		$ 31			$ 412,576		$ (76)	$ (313,369)
Ending balance (in shares) at Sep. 30, 2021			32,607,000		200,000

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating activities
Net loss	$ (43,922)	$ (52,376)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,153	1,208
Stock-based compensation expense	9,809	8,176
Amortization (accretion) of premiums (discounts) on investments	35	(39)
Unrealized (gain) loss on marketable equity securities	(590)	2,419
Loss on disposal of asset	5	4
Non-cash lease expense	276	206
Changes in operating assets and liabilities:
Accounts receivable	(323)	(58)
Deferred offering costs	0	(52)
Interest receivable	145	(54)
Prepaid expenses and other current assets	1,443	(1,702)
Income taxes receivable	2,346	(32)
Other assets	41	24
Accounts payable	354	(615)
Accrued expenses and other liabilities	1,239	(2,061)
Deferred revenue	0	(7,783)
Operating lease liability	(687)	(74)
Net cash used in operating activities	(28,676)	(52,809)
Investing activities
Purchases of property and equipment	(239)	(185)
Purchases of investments	0	(156,670)
Maturities of investments	52,713	119,675
Net cash provided by (used in) investing activities	52,474	(37,180)
Financing activities
Proceeds from exercise of stock options	89	557
Proceeds from common stock and pre-funded warrants sold, net of underwriters’ discount and costs	0	70,064
Proceeds from at-the-market offering, net of issuance costs	2,575	0
Net cash provided by financing activities	2,664	70,621
Net increase (decrease) in cash, cash equivalents and restricted cash	26,462	(19,368)
Cash, cash equivalents and restricted cash at beginning of period	78,359	54,200
Cash, cash equivalents and restricted cash at end of period	104,821	34,832
Supplemental cash flow information:
Public offering costs unpaid at period end	41	87
Cash paid included in measurement of lease liabilities	2,227	1,685
Pre-funded stock warrants issued	$ 0	$ 16,736

Nature of Business

Nature of Business	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business Concert Pharmaceuticals, Inc., or the Company, was incorporated on April 12, 2006 as a Delaware corporation and has its operations based in Lexington, Massachusetts. The Company is a clinical stage biopharmaceutical company that is developing small molecule drugs that it discovered through the application of its deuterated chemical entity platform, or DCE Platform ® . Selective incorporation of deuterium into known molecules has the potential, on a case-by-case basis, to provide better pharmacokinetic or metabolic properties, thereby enhancing their clinical safety, tolerability or efficacy. As discussed in detail in the “Overview” section in Part I, Item 2. of this Quarterly Report on Form 10-Q, the Company’s most advanced product candidate is CTP-543, which it is evaluating in a Phase 3 clinical program for the treatment of alopecia areata, a serious autoimmune dermatological condition. The Company is also assessing a number of earlier-stage pipeline candidates. Liquidity and Going Concern As of September 30, 2021, the Company had cash and cash equivalents of $103.7 million and net working capital of $100.9 million. The Company has incurred cumulative net losses of $313.4 million since inception and requires capital to continue future development activities. The Company does not have any products approved for sale and has not generated any revenue from product sales. The Company has financed its operations primarily through the public offering and private placement of its equity, debt financing, funding from collaborations and patent assignments, asset sales and other arrangements. The Company expects its expenses to increase in connection with its ongoing activities, particularly as it conducts its Phase 3 clinical trials of CTP-543 in alopecia areata. For information regarding the Company’s recently completed equity financings, see Note 12. The Company is subject to risks common to companies in the biotechnology industry, including, but not limited to, risks of failure or unsatisfactory results of nonclinical studies and clinical trials, the need to obtain additional financing to fund the future development of its pipeline, the need to obtain marketing approval for its product candidates, the need to successfully commercialize and gain market acceptance of its product candidates, dependence on key personnel, protection of proprietary technology, compliance with government regulations, development by competitors of technological innovations and ability to transition from pilot-scale manufacturing to large-scale production of products. Under Accounting Standards Codification, or ASC, Topic 205-40, Presentation of Financial Statements - Going Concern , management is required at each reporting period to evaluate whether there are conditions and events, considered in the aggregate, that raise substantial doubt about an entity's ability to continue as a going concern within one year after the date that the financial statements are issued. This evaluation initially does not take into consideration the potential mitigating effect of management’s plans that have not been fully implemented as of the date the financial statements are issued. When substantial doubt exists, management evaluates whether the mitigating effect of its plans sufficiently alleviates the substantial doubt about the Company’s ability to continue as a going concern. The mitigating effect of management's plans, however, is only considered if both (i) it is probable that the plans will be effectively implemented within one year after the date that the financial statements are issued and (ii) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. Generally, to be considered probable of being effectively implemented, the plans must have been approved by the Company’s board of directors before the date that the financial statements are issued. Successful completion of the Company’s development program and, ultimately, the attainment of profitable operations are dependent upon future events, including obtaining adequate financing to support the Company’s cost structure and operating plan. Management’s plans to alleviate its financing requirements include, among other things, pursuing one or more of the following steps to raise additional capital, none of which can be guaranteed or are entirely within the Company’s control: • raise funding through the sale of the Company’s common stock; • raise funding through debt financing; and • establish collaborations with potential partners to advance the Company’s product pipeline. Based on the Company’s current operating plan, management believes that its current cash and cash equivalents, including the net proceeds of the financing that the Company completed on November 5, 2021, will allow the Company to meet its liquidity requirements into the fourth quarter of 2022. The Company’s history of significant losses, its negative cash flows from operations, its limited liquidity resources currently on hand and its dependence on its ability to obtain additional financing to fund its operations after the current resources are exhausted, about which there can be no certainty, have resulted in management’s assessment that there is substantial doubt about the Company’s ability to continue as a going concern for a period of at least twelve months from the issuance date of this Quarterly Report on Form 10-Q. The accompanying condensed consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business, and do not include any adjustments that may result from the outcome of this uncertainty. If the Company is unable to raise capital when needed or on acceptable terms, or if it is unable to procure collaboration arrangements to advance its programs, the Company would be forced to discontinue some of its operations or develop and implement a plan to further extend payables, reduce overhead or scale back its current operating plan until sufficient additional capital is raised to support further operations. There can be no assurance that such a plan would be successful.

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	Basis of Presentation and Significant Accounting Policies Basis of Presentation The condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring accruals and revisions of estimates, considered necessary for a fair presentation of the condensed consolidated financial statements have been included. Interim results for the nine months ended September 30, 2021 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2021 or any other future period. The accompanying condensed consolidated financial statements reflect the accounts of the Company and its subsidiaries. All intercompany transactions between the Company and its subsidiaries have been eliminated. Management has determined that the Company operates in one segment: the development of pharmaceutical products on its own behalf or in collaboration with others. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the Company’s consolidated financial statements and the accompanying notes included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2020 filed with the Securities and Exchange Commission, or SEC, on February 25, 2021. Unless otherwise indicated, all amounts in the following tables are in thousands except share and per share amounts. Use of Estimates and Summary of Significant Accounting Policies The preparation of the consolidated financial statements in conformity with U.S. generally accepted accounting principles, or GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, equity, revenue, expenses and the disclosure of contingent assets and liabilities and the Company’s ability to continue as a going concern. In preparing the consolidated financial statements, management used estimates in the following areas, among others: revenue recognition; prepaid and accrued research and development expenses; stock-based compensation expense; and the evaluation of the existence of conditions and events that raise substantial doubt regarding the Company’s ability to continue as a going concern. Actual results could differ from those estimates. During the nine months ended September 30, 2021, there have been no material changes to the significant accounting policies previously disclosed in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2020. Pending Accounting Pronouncements In June 2016, the Financial Accounting Standards Board issued Accounting Standards Update, or ASU, 2016-13, Financial Instruments-Credit Losses . This standard requires entities to measure all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions and reasonable and supportable forecasts. As a smaller reporting company, ASU 2016-13 will become effective for the Company for fiscal years beginning after December 15, 2022, and early adoption is permitted. The Company is currently evaluating the impact that ASU 2016-13 will have on its financial statements and related disclosures.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company has certain financial assets and liabilities that are recorded at fair value which have been classified as Level 1, 2 or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements: • Level 1—quoted prices for identical instruments in active markets; • Level 2—quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets; and • Level 3—valuations derived from valuation techniques in which one or more significant value drivers are unobservable. The tables below present information about the Company’s financial assets and liabilities that are measured and carried at fair value as of September 30, 2021 and December 31, 2020 and indicate the level within the fair value hierarchy where each measurement is classified. The carrying amounts reflected in the condensed consolidated balance sheets for cash, prepaid expenses and other current assets, restricted cash, accounts payable and accrued expenses approximate their fair value due to their short-term nature. Level 1 Level 2 Level 3 Total September 30, 2021 Cash equivalents: Money market funds $ 95,847 $ — $ — $ 95,847 Marketable equity securities: Corporate equity securities (Note 8) 2,559 — — 2,559 Total $ 98,406 $ — $ — $ 98,406 Level 1 Level 2 Level 3 Total December 31, 2020 Cash equivalents: Money market funds $ 69,928 $ — $ — $ 69,928 Investments, available for sale: U.S. Treasury obligations 25,528 — — 25,528 Government agency securities 8,737 18,501 — 27,238 Marketable equity securities: Corporate equity securities (Note 8) 1,969 — — 1,969 Total $ 106,162 $ 18,501 $ — $ 124,663

Cash, Cash Equivalents, Investm

Cash, Cash Equivalents, Investments and Marketable Equity Securities	9 Months Ended
	Sep. 30, 2021
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents, Investments and Marketable Equity Securities	Cash, Cash Equivalents, Investments and Marketable Equity Securities Cash equivalents include all highly liquid investments maturing within 90 days from the date of purchase. Investments consist of securities with original maturities greater than 90 days when purchased. The Company classifies these investments as available for sale and records them at fair value in the accompanying consolidated balance sheets. Unrealized gains or losses from equity securities are included in net income. Unrealized gains or losses from other investments, including debt securities, are included in accumulated other comprehensive loss. Premiums or discounts from par value are amortized to investment income over the life of the underlying investment. Cash, cash equivalents, available for sale investments and marketable equity securities included the following as of September 30, 2021 and December 31, 2020: Amortized Cost Unrealized Gains Unrealized Losses Fair Value September 30, 2021 Cash $ 7,817 $ — $ — $ 7,817 Money market funds 95,847 — — 95,847 Cash and cash equivalents $ 103,664 $ — $ — $ 103,664 September 30, 2021 Acquisition Value Unrealized Gains Unrealized Losses Fair Value Marketable equity securities (Note 8) $ 10,451 $ — $ (7,892) $ 2,559 Average Maturity Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2020 Cash $ 7,274 $ — $ — $ 7,274 Money market funds 69,928 — — 69,928 Cash and cash equivalents $ 77,202 $ — $ — $ 77,202 U.S. Treasury obligations 70 days $ 25,523 $ 5 $ — $ 25,528 Government agency securities 82 days 27,225 13 — 27,238 Investments, available for sale $ 52,748 $ 18 $ — $ 52,766 December 31, 2020 Acquisition Value Unrealized Gains Unrealized Losses Fair Value Marketable equity securities (Note 8) $ 10,451 $ — $ (8,482) $ 1,969

Restricted Cash

Restricted Cash	9 Months Ended
	Sep. 30, 2021
Cash and Cash Equivalents [Abstract]
Restricted Cash	Restricted Cash Restricted cash as of September 30, 2021 and 2020 was held as collateral for stand-by letters of credit issued by the Company to its landlord in connection with the current lease for its principal facilities located at 65 Hayden Avenue, Lexington, Massachusetts. For additional information regarding the Company’s lease, refer to Note 11. Cash, cash equivalents and restricted cash consisted of the following as of September 30, 2021 and 2020: September 30, September 30, Cash and cash equivalents $ 103,664 $ 33,675 Restricted cash 1,157 1,157 Total cash, cash equivalents and restricted cash shown in the statements of cash flows $ 104,821 $ 34,832

Accrued Expenses and Other Liab

Accrued Expenses and Other Liabilities	9 Months Ended
	Sep. 30, 2021
Payables and Accruals [Abstract]
Accrued Expenses and Other Liabilities	Accrued Expenses and Other Liabilities Accrued expenses and other liabilities consisted of the following as of September 30, 2021 and December 31, 2020: September 30, December 31, Accrued professional fees and other $ 603 $ 709 Employee compensation and benefits 2,402 3,690 Research and development expenses 7,336 4,618 Accrued expenses and other liabilities $ 10,341 $ 9,017 Employee compensation and benefits, net of current portion $ 62 $ 108 Accrued expenses and other liabilities, net of current portion $ 62 $ 108

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Deferred tax assets and deferred tax liabilities are recognized based on temporary differences between the financial reporting and tax basis of assets and liabilities using statutory rates. A valuation allowance is recorded against deferred tax assets if it is more likely than not that some or all of the deferred tax assets will not be realized. The Company’s ability to use its operating loss carryforwards and tax credits to offset future taxable income is subject to restrictions under Sections 382 and 383 of the U.S. Internal Revenue Code. Net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant stockholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code. Such changes would limit the Company’s use of its operating loss carryforwards and tax credits. In such a situation, the Company may be required to pay income taxes, even though significant operating loss carryforwards and tax credits exist. The Company records a provision or benefit for income taxes on ordinary pre-tax income or loss based on its estimated effective tax rate for the year. As of September 30, 2021, the Company forecasts an ordinary pre-tax loss for the year ended December 31, 2021 and, since it maintains a full valuation allowance on its deferred tax assets, the Company did not record an income tax be nefit relating to this period. During the nine months ended September 30, 2020, the Company recorded a benefit for income taxes of $85 thousand for interest accrued in a prior period under the installment sales method for the sale of CTP-656 to Vertex Pharmaceuticals, Inc., or Vertex. The Company adopted ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , effective January 1, 2020. Under ASU 2019-12, the Company, having a full valuation and a loss in continuing operations, will no longer include the impacts of items in other comprehensive income in determining intra-period allocation of tax expense for continuing operations. Under ASU 2019-12, the Company can apply this change to intra-period tax allocation on a prospective basis. For the nine months ended September 30, 2021 , the Company applied the tax allocation rules of ASU 2019-12 to the $18 thousand of unrealized losses on available for sale investments recognized in other comprehensive loss, which did not have a material impact on the consolidated financial statements or related disclosures.

Revenue

Revenue	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue	Revenue The Company’s revenue is generated through collaborative licensing agreements, patent assignments, intellectual property sales and asset sales. The Company generates its revenue through one segment. The revenue recognized under each of the Company’s arrangements during the current and prior periods is described below. Contract Assets The Company did not have a contract asset as of September 30, 2021 or December 31, 2020. Contract Liabilities As of September 30, 2021 and December 31, 2020, the Company had $2.8 million in contract liabilities related to variable consideration paid in advance but currently constrained from recognition. The $2.8 million in contract liabilities consisted of deferred revenue related to a payment received from GlaxoSmithKline that the Company will not recognize as revenue until all repayment obligations lapse. Revenue Arrangements Vertex In July 2017, the Company completed the sale of worldwide development and commercialization rights to CTP-656, now known as VX-561, and other assets related to the treatment of cystic fibrosis to Vertex. Pursuant to the Asset Purchase Agreement with Vertex, or the Vertex Agreement, the Company received $160.0 million in cash upon closing. Additionally, upon the achievement of certain milestone events, Vertex agreed to pay the Company an aggregate of up to $90.0 million, or the Milestone Obligation. In May 2021, the Company entered into an amendment to the Vertex Agreement, or the Vertex Amendment. Pursuant to the Vertex Amendment, Vertex paid the Company $32.0 million in cash in exchange for the removal of the Milestone Obligation. As a result of the Vertex Amendment, the Company is not entitled to receive any further payments pursuant to the Vertex Agreement. The Vertex Amendment changes the future obligations due from Vertex under the Vertex Agreement and was therefore treated as a contract modification. Since the Vertex Amendment does not provide for any new distinct goods and services, and the single performance obligation related to the arrangement was previously satisfied, the Company recognized the $32.0 million payment from Vertex as Other Revenue during the three months ended June 30, 2021. Previously, the variable consideration related to the Milestone Obligation was considered fully constrained due to the uncertainty associated with the achievement of the milestones. Pursuant to the Vertex Amendment, Vertex is no longer obligated to make these future milestone payments, and as a result, they are no longer considered variable consideration. There are no performance obligations or variable consideration remaining associated with the Vertex Agreement. Processa On October 4, 2017, the Company entered into an Option and License Agreement, or the Option, with Promet Therapeutics, LLC, or Promet, pursuant to which the Company granted Promet an option to obtain an exclusive license to CTP-499, a deuterated analog of 1-(S)-5-hydroxyhexyl-3,7-dimethylxanthine, or HDX, an active metabolite of pentoxifylline, provided certain conditions were met. On October 5, 2017, Promet closed an asset purchase with Heatwurx, Inc., a public company, creating Processa Pharmaceuticals, Inc., or Processa. On March 19, 2018, the Company entered into an amendment to the Option, or the Promet Amendment, and a Securities Purchase Agreement with both Promet and Processa. Pursuant to the Promet Amendment, the Company granted Promet, who then assigned to Processa, an exclusive, worldwide, royalty-bearing license to develop, manufacture and commercialize CTP-499, now known as PCS-499. Upon transfer of the license and as consideration for the license, the Company received 2,090,301 shares of common stock of Processa. In December 2019, Processa implemented a reverse stock split, and the Company now owns 298,615 shares of common stock of Processa. The Company is also eligible to receive royalties on worldwide net sales. The Promet Amendment contained one performance obligation: an exclusive, worldwide, royalty-bearing license to develop, manufacture and commercialize CTP-499. The Company determined that the transaction price was $10.5 million, which was based on the fair value of the non-cash consideration received on March 19, 2018, which consisted of 2,090,301 shares of publicly traded common stock of Processa. The transaction price of $10.5 million was allocated to the single performance obligation. The performance obligation was considered satisfied at contract inception, as the exclusive license transferred control to the customer at this point in time. Accordingly, revenue of $10.5 million was recognized during the first quarter of 2018. Subsequent changes to the fair value of the underlying securities are recognized as unrealized gains or losses on marketable equity securities in the condensed consolidated statements of operations and comprehensive loss. The Promet Amendment contains consideration that is variable based on royalties upon the customer’s commercial success with the licensed product. The consideration related to royalty payments is considered variable consideration that is fully constrained in accordance with the royalty recognition constraint. The variable consideration related to royalties will be recognized in the period the products are sold by Processa and the Company has a present right to payment. For the three and nine months ended September 30, 2021, the Company recognized no revenue and $9 thousand in revenue, respectively, related to intellectual property cost reimbursements. For the three and nine months ended September 30, 2020, the Company recognized $3 thousand and $14 thousand, respectively, in revenue related to intellectual property cost reimbursements.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based CompensationThe Company’s equity incentive plans provide for the issuance of a variety of stock-based awards, including incentive stock options, nonstatutory stock options and awards of stock, to directors, officers and employees of the Company, as well as consultants and advisors to the Company. As of September 30, 2021, the Company has granted awards in the form of stock options and restricted stock units, or RSUs. The stock options generally have been granted with an exercise price equal to the closing market price of the Company’s common stock on the date of grant, a vesting period of one three expiration date no later than ten years from the date of grant. The Company has granted performance-based and service-based RSUs with a vesting period of one two Effective January 1, 2021, an additional 1,274,487 shares were added to the Company’s 2014 Stock Incentive Plan, or the 2014 Plan, for future issuance pursuant to the terms of the 2014 Plan. As of September 30, 2021, there were 1,261,005 shares of common stock available for future awards under the 2014 Plan. Total stock-based compensation expense related to all stock-based options and awards recognized in the condensed consolidated statements of operations and comprehensive loss consisted of: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development $ 1,654 $ 1,555 $ 5,250 $ 4,226 General and administrative 1,470 1,340 4,559 3,950 Total stock-based compensation expense $ 3,124 $ 2,895 $ 9,809 $ 8,176 Stock Options Stock options are valued using the Black-Scholes-Merton option valuation model, and compensation cost is recognized based on such fair value over the period of vesting. The weighted-average fair value of options granted in the three and nine months ended September 30, 2021 and 2020 reflect the following weighted-average assumptions: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Expected volatility 70.10 % 70.11 % 69.83 % 68.59 % Expected term 6.0 years 6.0 years 6.0 years 6.0 years Risk-free interest rate 1.08 % 0.37 % 0.60 % 1.32 % Expected dividend yield — % — % — % — % The following table provides certain information related to the Company’s outstanding stock options: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (Amounts in thousands, except per share data) Weighted-average fair value of options granted, per option $ 2.13 $ 5.68 $ 7.09 $ 6.53 Aggregate grant date fair value of options vested during the period $ 1,939 $ 2,198 $ 6,115 $ 6,434 Total cash received from exercises of stock options $ — $ 13 $ 89 $ 557 Total intrinsic value of stock options exercised $ — $ 21 $ 42 $ 304 The following is a summary of stock option activity for the nine months ended September 30, 2021: Number of Weighted Weighted Aggregate (in years) (in thousands) Outstanding at December 31, 2020 4,652,870 $ 14.48 Granted 861,143 $ 11.57 Exercised (10,130) $ 8.80 Forfeited or expired (132,109) $ 13.84 Outstanding at September 30, 2021 5,371,774 $ 14.04 6.20 $ 1 Exercisable at September 30, 2021 3,819,478 $ 14.59 5.35 $ 1 Vested and expected to vest at September 30, 2021 (1) 5,246,524 $ 14.09 6.14 $ 1 (1) Represents the number of vested stock option shares as of September 30, 2021, plus the number of unvested stock option shares that the Company estimated as of September 30, 2021 would vest, based on the unvested stock option shares as of September 30, 2021 and an estimated forfeiture rate of 7%. As of September 30, 2021, there w as $10.6 million of unre cognized compensation cost related to stock options that are expected to vest. The stock option costs are expected to be recognized over a weighted-average remaining vesting period of 2.2 years. Restricted Stock Units During the nine months ended September 30, 2021, the Company granted 0.5 million RSUs to executives, employees and directors. RSUs are not included in issued and outstanding common stock until the shares have vested and settled. The fair value of an RSU is measured based on the market price of the underlying common stock on the date of grant. The following is a summary of RSU activity for the nine months ended September 30, 2021: Number of Weighted- Outstanding at December 31, 2020 661,033 $ 10.64 Granted 486,643 $ 9.74 Released (369,164) $ 10.49 Forfeited (43,126) $ 10.46 Outstanding at September 30, 2021 735,386 $ 10.13 As of September 30, 2021, there was $5.3 million of u nrecognized compensation cost related to RSUs that are expected to vest. The RSU costs are expected to be recognized over a weighted-average remaining vesting pe riod of 1.6 years .

Loss Per Share

Loss Per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Loss Per Share	Loss Per Share Basic net loss per common share is calculated by dividing net loss allocable to common stockholders by the weighted-average common shares outstanding during the period, without consideration of stock options and RSUs as common stock equivalents. The weighted-average common shares outstanding as of September 30, 2021 includes pre-funded warrants to purchase up to an aggregate of 1.8 million shares of common stock that were issued in connection with a public offering that closed in January 2020. For purposes of the diluted net loss per share calculation, common stock equivalents are excluded from the calculation if their effect would be anti-dilutive. As such, basic and diluted net loss per share applicable to common stockholders are the same for periods with a net loss. The following table illustrates the determination of loss per share for each period presented. Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (Amounts in thousands, except per share amounts) Numerator: Net loss applicable to common stockholders - basic and diluted (26,678) (18,908) (43,922) (52,376) Denominator: Weighted-average shares outstanding - basic and diluted 34,090 31,547 33,987 30,707 Net loss per share applicable to common stockholders - basic and diluted $ (0.78) $ (0.60) $ (1.29) $ (1.71) Anti-dilutive potential common stock equivalents excluded from the calculation of net loss per share: Stock options 5,372 4,692 5,372 4,692 Restricted stock units 735 662 735 662 Warrants 61 61 61 61

Commitments

Commitments	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments	Commitments Lease The Company currently has a lease, or the Lease, for approximately 56,000 square feet of office and laboratory space located at 65 Hayden Avenue, Lexington, Massachusetts, or the Premises. The Lease is classified as an operating lease. The lease term extends ten years following January 1, 2019. The Company is entitled to two five-year options to extend the Lease. The Lease provides for annual base rent of approximately $2.8 million in the first year following January 1, 2019, which increases on a yearly basis by 3.0% (subject to an abatement of base rent of approximately $0.5 million at the beginning of the second year of the lease term). There are no variable payments, exercise purchase options, penalties, fees or residual value guarantees under the Lease. The Company is also obligated to pay the landlord for certain costs, taxes and operating expenses related to the Premises, subject to certain exclusions. The Company recorded a liability for the Lease of $16.9 million on January 1, 2019. This lease liability is amortized over the remaining lease term in an amount equal to the difference between the cash rent paid and the monthly interest calculated on the remaining lease liability. As of September 30, 2021, the Company had a current lease liability of $1.1 million and a non-current lease liability of $14.2 million recorded in its condensed consolidated balance sheets. On January 1, 2019, the Company recorded a right-of-use asset in the amount of $9.5 million, which represents the lease liability of $16.9 million, adjusted for previously accrued rent of $2.9 million and previously recorded unamortized lease incentives in the amount of $4.5 million. The right-of-use asset is amortized over the remaining lease term in an amount equal to the difference between the calculated straight-line expense of the total lease payments less the monthly interest calculated on the remaining lease liability. As of September 30, 2021, the Company had a long-term lease asset of $8.7 million recorded in its condensed consolidated balance sheets. The Company recognizes lease expense, calculated as the remaining cost of the Lease allocated over the remaining lease term, on a straight-line basis. Lease expense is presented as part of continuing operations in the condensed consolidated statements of operations and comprehensive loss. For the nine months ended September 30, 2021, the Company recogniz ed $1.8 million in lease expense. For the nine months ended September 30, 2021, the Company paid $2.2 million in rent. As a payment arising from an operating lease, the $2.2 million is classified within operating activities in the condensed consolidated statements of cash flows. For the nine months ended September 30, 2021 and 2020, the weighted-average remaining lease term was 7.25 years and 8.25 years, respectively, and the weighted-average discount rate was 13.08%.

Open Market Sale Agreement

Open Market Sale Agreement	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Open Market Sale Agreement	Open Market Sale Agreement On March 1, 2019, the Company entered into an Open Market Sale Agreement, or the ATM Agreement, with Jefferies LLC, or Jefferies, with respect to an at-the-market offering program under which the Company may offer and sell, from time to time at its sole discretion, shares of its common stock having an aggregate offering price of up to $50.0 million, referred to as Placement Shares, through Jefferies as its sales agent. The Company will pay Jefferies a commission equal to 3.0% of the gross sales proceeds of any Placement Shares sold through Jefferies under the ATM Agreement, and also has provided Jefferies with customary indemnification and contribution rights. On November 5, 2020, the Company entered into an amendment to the ATM Agreement with Jefferies to increase the aggregate offering price of Placement Shares that may be offered and sold pursuant to the ATM Agreement from up to $50.0 million to up to $100.0 million. However, on March 7, 2021, the Company’s ability to further use the first $50.0 million expired. As a result, from March 7, 2021 onward, the Company may only offer and sell up to an additional $50.0 million pursuant to the ATM Agreement. During the year ended December 31, 2019, the Company sold 36,167 shares of its common stock pursuant to the ATM Agreement for net proceeds of $0.4 million, after payment of cash commissions of 3.0% of the gross proceeds to Jefferies. Additionally, the Company incurred approximately $0.3 million during the year ended December 31, 2019 related to legal, accounting and other fees in connection with the ATM Agreement. During the year ended December 31, 2020, the Company sold 2,008,197 shares of its common stock pursuant to the ATM Agreement for net proceeds of $22.8 million, after payment of cash commissions of 3.0% of the gross proceeds to Jefferies. Additionally, the Company incurred approximately $0.3 million during the year ended December 31, 2020 related to legal, accounting and other fees in connection with the ATM Agreement. During the nine months ended September 30, 2021, the Company sold 165,323 shares of its common stock pursuant to the ATM Agreement for net proceeds of $2.0 million, after payment of cash commissions of 3.0% of the gross proceeds to Jefferies. Cash provided by financing activities for the nine months ended September 30, 2021 includes $0.5 million in net proceeds from sales pursuant to the ATM Agreement that had been classified as a receivable as of December 31, 2020.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsOn November 5, 2021, the Company closed a financing raising gross proceeds of $65.0 million. The financing consisted of the sale of (i) 13,997 shares of the Company’s Series X1 Preferred Stock, (ii) 2,253,000 shares of common stock, (iii) warrants to purchase up to 16,250 shares of Series X1 Preferred Stock and (iv) a portion of the Company’s right to receive potential future AVP-786 royalties under an existing licensing agreement with Avanir Pharmaceuticals, Inc., or Avanir, a subsidiary of Otsuka Pharmaceuticals Co., Ltd. Each share of Series X1 Preferred Stock is convertible into 1,000 shares of common stock at the holder’s election, subject to beneficial ownership limitations. If the warrants issued in connection with this financing are exercised in full, the Company would receive additional gross proceeds of $103.1 million.

Basis of Presentation, Signific

Basis of Presentation, Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring accruals and revisions of estimates, considered necessary for a fair presentation of the condensed consolidated financial statements have been included. Interim results for the nine months ended September 30, 2021 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2021 or any other future period. The accompanying condensed consolidated financial statements reflect the accounts of the Company and its subsidiaries. All intercompany transactions between the Company and its subsidiaries have been eliminated. Management has determined that the Company operates in one segment: the development of pharmaceutical products on its own behalf or in collaboration with others. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the Company’s consolidated financial statements and the accompanying notes included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2020 filed with the Securities and Exchange Commission, or SEC, on February 25, 2021. Unless otherwise indicated, all amounts in the following tables are in thousands except share and per share amounts.
Use of Estimates and Summary of Significant Accounting Policies	Use of Estimates and Summary of Significant Accounting Policies The preparation of the consolidated financial statements in conformity with U.S. generally accepted accounting principles, or GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, equity, revenue, expenses and the disclosure of contingent assets and liabilities and the Company’s ability to continue as a going concern. In preparing the consolidated financial statements, management used estimates in the following areas, among others: revenue recognition; prepaid and accrued research and development expenses; stock-based compensation expense; and the evaluation of the existence of conditions and events that raise substantial doubt regarding the Company’s ability to continue as a going concern. Actual results could differ from those estimates. During the nine months ended September 30, 2021, there have been no material changes to the significant accounting policies previously disclosed in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2020.
Pending Accounting Pronouncements	Pending Accounting Pronouncements In June 2016, the Financial Accounting Standards Board issued Accounting Standards Update, or ASU, 2016-13, Financial Instruments-Credit Losses . This standard requires entities to measure all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions and reasonable and supportable forecasts. As a smaller reporting company, ASU 2016-13 will become effective for the Company for fiscal years beginning after December 15, 2022, and early adoption is permitted. The Company is currently evaluating the impact that ASU 2016-13 will have on its financial statements and related disclosures.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of financial assets and liabilities recognized at fair value	The tables below present information about the Company’s financial assets and liabilities that are measured and carried at fair value as of September 30, 2021 and December 31, 2020 and indicate the level within the fair value hierarchy where each measurement is classified. The carrying amounts reflected in the condensed consolidated balance sheets for cash, prepaid expenses and other current assets, restricted cash, accounts payable and accrued expenses approximate their fair value due to their short-term nature. Level 1 Level 2 Level 3 Total September 30, 2021 Cash equivalents: Money market funds $ 95,847 $ — $ — $ 95,847 Marketable equity securities: Corporate equity securities (Note 8) 2,559 — — 2,559 Total $ 98,406 $ — $ — $ 98,406 Level 1 Level 2 Level 3 Total December 31, 2020 Cash equivalents: Money market funds $ 69,928 $ — $ — $ 69,928 Investments, available for sale: U.S. Treasury obligations 25,528 — — 25,528 Government agency securities 8,737 18,501 — 27,238 Marketable equity securities: Corporate equity securities (Note 8) 1,969 — — 1,969 Total $ 106,162 $ 18,501 $ — $ 124,663

Cash, Cash Equivalents, Inves_2

Cash, Cash Equivalents, Investments and Marketable Equity Securities (Tables)	9 Months Ended
	Sep. 30, 2021
Cash and Cash Equivalents [Abstract]
Schedule of cash equivalents and short-term and long-term investments	Cash, cash equivalents, available for sale investments and marketable equity securities included the following as of September 30, 2021 and December 31, 2020: Amortized Cost Unrealized Gains Unrealized Losses Fair Value September 30, 2021 Cash $ 7,817 $ — $ — $ 7,817 Money market funds 95,847 — — 95,847 Cash and cash equivalents $ 103,664 $ — $ — $ 103,664 September 30, 2021 Acquisition Value Unrealized Gains Unrealized Losses Fair Value Marketable equity securities (Note 8) $ 10,451 $ — $ (7,892) $ 2,559 Average Maturity Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2020 Cash $ 7,274 $ — $ — $ 7,274 Money market funds 69,928 — — 69,928 Cash and cash equivalents $ 77,202 $ — $ — $ 77,202 U.S. Treasury obligations 70 days $ 25,523 $ 5 $ — $ 25,528 Government agency securities 82 days 27,225 13 — 27,238 Investments, available for sale $ 52,748 $ 18 $ — $ 52,766 December 31, 2020 Acquisition Value Unrealized Gains Unrealized Losses Fair Value Marketable equity securities (Note 8) $ 10,451 $ — $ (8,482) $ 1,969

Restricted Cash (Tables)

Restricted Cash (Tables)	9 Months Ended
	Sep. 30, 2021
Cash and Cash Equivalents [Abstract]
Schedule of restrictions on cash and cash equivalents	Cash, cash equivalents and restricted cash consisted of the following as of September 30, 2021 and 2020: September 30, September 30, Cash and cash equivalents $ 103,664 $ 33,675 Restricted cash 1,157 1,157 Total cash, cash equivalents and restricted cash shown in the statements of cash flows $ 104,821 $ 34,832

Accrued Expenses and Other Li_2

Accrued Expenses and Other Liabilities (Tables)	9 Months Ended
	Sep. 30, 2021
Payables and Accruals [Abstract]
Schedule of accrued expenses and other liabilities	Accrued expenses and other liabilities consisted of the following as of September 30, 2021 and December 31, 2020: September 30, December 31, Accrued professional fees and other $ 603 $ 709 Employee compensation and benefits 2,402 3,690 Research and development expenses 7,336 4,618 Accrued expenses and other liabilities $ 10,341 $ 9,017 Employee compensation and benefits, net of current portion $ 62 $ 108 Accrued expenses and other liabilities, net of current portion $ 62 $ 108

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Schedule of stock-based compensation expense related to all stock based awards recognized in statements of operations and comprehensive income (loss)	Total stock-based compensation expense related to all stock-based options and awards recognized in the condensed consolidated statements of operations and comprehensive loss consisted of: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development $ 1,654 $ 1,555 $ 5,250 $ 4,226 General and administrative 1,470 1,340 4,559 3,950 Total stock-based compensation expense $ 3,124 $ 2,895 $ 9,809 $ 8,176
Schedule of estimated weighted-average assumptions of options granted	The weighted-average fair value of options granted in the three and nine months ended September 30, 2021 and 2020 reflect the following weighted-average assumptions: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Expected volatility 70.10 % 70.11 % 69.83 % 68.59 % Expected term 6.0 years 6.0 years 6.0 years 6.0 years Risk-free interest rate 1.08 % 0.37 % 0.60 % 1.32 % Expected dividend yield — % — % — % — %
Schedule of outstanding stock options	The following table provides certain information related to the Company’s outstanding stock options: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (Amounts in thousands, except per share data) Weighted-average fair value of options granted, per option $ 2.13 $ 5.68 $ 7.09 $ 6.53 Aggregate grant date fair value of options vested during the period $ 1,939 $ 2,198 $ 6,115 $ 6,434 Total cash received from exercises of stock options $ — $ 13 $ 89 $ 557 Total intrinsic value of stock options exercised $ — $ 21 $ 42 $ 304
Summary of stock option activity	The following is a summary of stock option activity for the nine months ended September 30, 2021: Number of Weighted Weighted Aggregate (in years) (in thousands) Outstanding at December 31, 2020 4,652,870 $ 14.48 Granted 861,143 $ 11.57 Exercised (10,130) $ 8.80 Forfeited or expired (132,109) $ 13.84 Outstanding at September 30, 2021 5,371,774 $ 14.04 6.20 $ 1 Exercisable at September 30, 2021 3,819,478 $ 14.59 5.35 $ 1 Vested and expected to vest at September 30, 2021 (1) 5,246,524 $ 14.09 6.14 $ 1 (1) Represents the number of vested stock option shares as of September 30, 2021, plus the number of unvested stock option shares that the Company estimated as of September 30, 2021 would vest, based on the unvested stock option shares as of September 30, 2021 and an estimated forfeiture rate of 7%.
Summary of RSU activity	The following is a summary of RSU activity for the nine months ended September 30, 2021: Number of Weighted- Outstanding at December 31, 2020 661,033 $ 10.64 Granted 486,643 $ 9.74 Released (369,164) $ 10.49 Forfeited (43,126) $ 10.46 Outstanding at September 30, 2021 735,386 $ 10.13

Loss Per Share (Tables)

Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Computation of basic and diluted earnings (loss) per share	The following table illustrates the determination of loss per share for each period presented. Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (Amounts in thousands, except per share amounts) Numerator: Net loss applicable to common stockholders - basic and diluted (26,678) (18,908) (43,922) (52,376) Denominator: Weighted-average shares outstanding - basic and diluted 34,090 31,547 33,987 30,707 Net loss per share applicable to common stockholders - basic and diluted $ (0.78) $ (0.60) $ (1.29) $ (1.71) Anti-dilutive potential common stock equivalents excluded from the calculation of net loss per share: Stock options 5,372 4,692 5,372 4,692 Restricted stock units 735 662 735 662 Warrants 61 61 61 61

Nature of Business - Additional

Nature of Business - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 103,664	$ 77,202	$ 33,675
Net working capital	100,900
Accumulated deficit	$ (313,369)	$ (269,447)

Basis of Presentation, Signif_2

Basis of Presentation, Significant Accounting Policies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2021segment
Accounting Policies [Abstract]
Number of segments	1

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Recognized at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, cash equivalents	$ 103,664	$ 77,202
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, cash equivalents	95,847	69,928
Fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Corporate equity securities (Note 8)	2,559	1,969
Total financial assets at fair value	98,406	124,663
Fair value measurements | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Corporate equity securities (Note 8)	2,559	1,969
Total financial assets at fair value	98,406	106,162
Fair value measurements | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Corporate equity securities (Note 8)	0	0
Total financial assets at fair value	0	18,501
Fair value measurements | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Corporate equity securities (Note 8)	0	0
Total financial assets at fair value	0	0
Fair value measurements | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, investments available-for-sale securities		25,528
Fair value measurements | U.S. Treasury obligations | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, investments available-for-sale securities		25,528
Fair value measurements | U.S. Treasury obligations | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, investments available-for-sale securities		0
Fair value measurements | U.S. Treasury obligations | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, investments available-for-sale securities		0
Fair value measurements | Government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, investments available-for-sale securities		27,238
Fair value measurements | Government agency securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, investments available-for-sale securities		8,737
Fair value measurements | Government agency securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, investments available-for-sale securities		18,501
Fair value measurements | Government agency securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, investments available-for-sale securities		0
Fair value measurements | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, cash equivalents	95,847	69,928
Fair value measurements | Money market funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, cash equivalents	95,847	69,928
Fair value measurements | Money market funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, cash equivalents	0	0
Fair value measurements | Money market funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value, cash equivalents	$ 0	$ 0

Cash, Cash Equivalents, Inves_3

Cash, Cash Equivalents, Investments and Marketable Equity Securities - Cash Equivalents and Short-term and Long-term Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Cash and Cash Equivalents
Amortized cost, cash and cash equivalents	$ 103,664	$ 77,202	$ 33,675
Fair value, cash and cash equivalent	103,664	77,202
Investments, available for sale
Debt Securities
Amortized cost, investments available for sale		52,748
Unrealized Gains		18
Unrealized Losses		0
Fair value, available-for-sale securities		52,766
U.S. Treasury obligations
Debt Securities
Amortized cost, investments available for sale		25,523
Unrealized Gains		5
Unrealized Losses		0
Fair value, available-for-sale securities		25,528
Government agency securities
Debt Securities
Amortized cost, investments available for sale		27,225
Unrealized Gains		13
Unrealized Losses		0
Fair value, available-for-sale securities		27,238
Marketable equity securities
Marketable Securities
Acquisition Value	10,451	10,451
Unrealized Gains	0	0
Unrealized Losses	(7,892)	(8,482)
Fair Value	2,559	1,969
Cash
Cash and Cash Equivalents
Amortized cost, cash and cash equivalents	7,817	7,274
Fair value, cash and cash equivalent	7,817	7,274
Money market funds
Cash and Cash Equivalents
Amortized cost, cash and cash equivalents	95,847	69,928
Fair value, cash and cash equivalent	$ 95,847	$ 69,928
Measurement Input, Expected Term | U.S. Treasury obligations
Debt Securities
Average maturity (in days)		70 days
Measurement Input, Expected Term | Government agency securities
Debt Securities
Average maturity (in days)		82 days

Restricted Cash (Details)

Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 103,664	$ 77,202	$ 33,675
Restricted cash	1,157	1,157	1,157
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	$ 104,821	$ 78,359	$ 34,832	$ 54,200

Accrued Expenses and Other Li_3

Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued professional fees and other	$ 603	$ 709
Employee compensation and benefits	2,402	3,690
Research and development expenses	7,336	4,618
Accrued expenses and other liabilities	10,341	9,017
Employee compensation and benefits, net of current portion	62	108
Accrued expenses, net of current portion	$ 62	$ 108

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income tax benefit	$ 0			$ 0			$ 0	$ 85
Unrealized loss on short-term investments	$ 0	$ 2	$ 16	$ 141	$ 316	$ (523)	$ 18	$ (66)

Revenue - Additional Informatio

Revenue - Additional Information (Details)	9 Months Ended
	Sep. 30, 2021USD ($)segment	Dec. 31, 2020USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative
Number of segments | segment	1
Contract asset	$ 0	$ 0
Contract liability	2,800,000	$ 2,800,000
GlaxoSmithKline
Collaborative Arrangement and Arrangement Other than Collaborative
Contract liability	$ 2,800,000

Revenue - Vertex (Details)

Revenue - Vertex (Details) - USD ($) $ in Thousands	Mar. 19, 2018	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020	Mar. 31, 2018	Sep. 30, 2021	Sep. 30, 2020	May 31, 2021	Jul. 31, 2017
Revenue Recognition, Milestone Method
Total revenue	$ 10,500	$ 543		$ 1,501	$ 10,500	$ 32,565	$ 7,895
Other revenue
Revenue Recognition, Milestone Method
Total revenue		$ 539		$ 0		$ 32,539	$ 0
Vertex
Revenue Recognition, Milestone Method
Proceeds from milestone settlement								$ 32,000
Vertex | Other revenue
Revenue Recognition, Milestone Method
Total revenue			$ 32,000
Disposed of by sale, not discontinued operations | Assets for synthesis and research and development for treating Cystic Fibrosis
Revenue Recognition, Milestone Method
Cash consideration									$ 160,000
Disposed of by sale, not discontinued operations | Assets for synthesis and research and development for treating Cystic Fibrosis | Indemnification agreement
Revenue Recognition, Milestone Method
Contingent consideration receivable									$ 90,000

Revenue - Processa (Details)

Revenue - Processa (Details) - USD ($)	Mar. 19, 2018	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2018	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Revenue Recognition, Milestone Method
Shares owned (in shares)		32,406,815			32,406,815		31,862,198
Allocable arrangement consideration	$ 10,500,000	$ 543,000	$ 1,501,000	$ 10,500,000	$ 32,565,000	$ 7,895,000
Processa
Revenue Recognition, Milestone Method
Equity received from sale (in shares)	2,090,301
Shares owned (in shares)								298,615
Allocable arrangement consideration		$ 0	$ 3,000		$ 9,000	$ 14,000

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	Jan. 01, 2021	Sep. 30, 2021
2014 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award
Additional shares issued under the plan (in shares)	1,274,487
Common stock available for future award grant (in shares)		1,261,005
Stock options
Share-based Compensation Arrangement by Share-based Payment Award
Total unrecognized compensation cost related to unvested options		$ 10.6
Total unrecognized compensation cost, weighted-average recognition period (years)		2 years 2 months 12 days
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)		1 year 7 months 6 days
Number of RSUs, granted (in shares)		486,643
Total unrecognized compensation cost related to restricted stock units		$ 5.3
Minimum | Stock options
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)		1 year
Minimum | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)		1 year
Median | Stock options
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)		3 years
Median | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)		2 years
Maximum | Stock options
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)		4 years
Awards expiration period (in years)		10 years
Maximum | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)		3 years

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense Related to All Stock Based Awards Recognized in Statements of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation expense	$ 3,124	$ 2,895	$ 9,809	$ 8,176
Research and development
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation expense	1,654	1,555	5,250	4,226
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation expense	$ 1,470	$ 1,340	$ 4,559	$ 3,950

Stock-Based Compensation - Esti

Stock-Based Compensation - Estimated Weighted-Average Assumptions of Options Granted (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Payment Arrangement [Abstract]
Expected volatility	70.10%	70.11%	69.83%	68.59%
Expected term (in years)	6 years	6 years	6 years	6 years
Risk-free interest rate	1.08%	0.37%	0.60%	1.32%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

Stock-Based Compensation - Fair

Stock-Based Compensation - Fair Value of Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Payment Arrangement [Abstract]
Weighted average grant date fair value of options granted, per option (in dollars per share)	$ 2.13	$ 5.68	$ 7.09	$ 6.53
Aggregate grant date fair value of options vested during the period	$ 1,939	$ 2,198	$ 6,115	$ 6,434
Total cash received from exercises of stock options	0	13	89	557
Total intrinsic value of stock options exercised	$ 0	$ 21	$ 42	$ 304

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)$ / sharesshares
Number of Option Shares
Number of options, Outstanding beginning balance (in shares) | shares	4,652,870
Number of options, Granted (in shares) | shares	861,143
Number of options, Exercised (in shares) | shares	(10,130)
Number of options, Forfeited or expired (in shares) | shares	(132,109)
Number of options, Outstanding ending balance (in shares) | shares	5,371,774
Number of options, Exercisable (in shares) | shares	3,819,478
Number of options, Vested and expected to vest (in shares) | shares	5,246,524
Weighted Average Exercise Price per Share
Weighted average exercise price per share, Outstanding at beginning of year (in dollars per share) | $ / shares	$ 14.48
Weighted average exercise price per share, Granted (in dollars per share) | $ / shares	11.57
Weighted average exercise price per share, Exercised (in dollars per share) | $ / shares	8.80
Weighted average exercise price per share, Forfeited or expired (in dollars per share) | $ / shares	13.84
Weighted average exercise price per share, Outstanding ending balance (in dollars per share) | $ / shares	14.04
Weighted average exercise price per share, Exercisable (in dollars per share) | $ / shares	14.59
Weighted average exercise price per share, Vested and expected to vest (in dollars per share) | $ / shares	$ 14.09
Weighted Average Remaining Contractual Term (In years)
Weighted average remaining contractual term, Outstanding (in years)	6 years 2 months 12 days
Weighted average remaining contractual term, Exercisable (in years)	5 years 4 months 6 days
Weighted average remaining contractual term, Vested and expected to vest (in years)	6 years 1 month 20 days
Aggregate Intrinsic Value
Aggregate intrinsic value, Outstanding | $	$ 1
Aggregate intrinsic value, Exercisable | $	1
Aggregate intrinsic value, Vested and expected to vest | $	$ 1
Estimated forfeiture rate (percent)	7.00%

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of RSU Activity (Details) - Restricted stock units	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Number of RSUs
Number of RSUs, Outstanding beginning balance (in shares) | shares	661,033
Number of RSUs, Granted (in shares) | shares	486,643
Number of RSUs, Released (in shares) | shares	(369,164)
Number of RSUs, Forfeited (in shares) | shares	(43,126)
Number of RSUs, Outstanding ending balance (in shares) | shares	735,386
Weighted- Average Grant Date Fair Value
Weighted average grant date fair value, Outstanding at beginning of year (in dollars per share) | $ / shares	$ 10.64
Weighted average grant date fair value, Granted (in dollars per share) | $ / shares	9.74
Weighted average grant date fair value, Released (in dollars per share) | $ / shares	10.49
Weighted average grant date fair value, Forfeited (in dollars per share) | $ / shares	10.46
Weighted average grant date fair value, Outstanding at ending of year (in dollars per share) | $ / shares	$ 10.13

Loss Per Share - Narratives (De

Loss Per Share - Narratives (Details) shares in Millions	Sep. 30, 2021shares
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share
Warrants to purchase common shares (in shares)	1.8

Loss Per Share - Computation of

Loss Per Share - Computation of Basic and Diluted Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net loss applicable to common stockholders - basic and diluted	$ (26,678)	$ 5,425	$ (22,669)	$ (18,908)	$ (12,991)	$ (20,477)	$ (43,922)	$ (52,376)
Denominator:
Weighted average number of shares outstanding, basic (in shares)	34,090			31,547			33,987	30,707
Weighted average number of shares outstanding, diluted (in shares)	34,090			31,547			33,987	30,707
Net loss per share applicable to common stockholders - basic (in dollars per share)	$ (0.78)			$ (0.60)			$ (1.29)	$ (1.71)
Net loss per share applicable to common stockholders - diluted (in dollars per share)	$ (0.78)			$ (0.60)			$ (1.29)	$ (1.71)
Stock options
Anti-dilutive potential common stock equivalents excluded from the calculation of net loss per share:
Anti-dilutive stock options, restricted stock units, and warrants (in shares)	5,372			4,692			5,372	4,692
Restricted stock units
Anti-dilutive potential common stock equivalents excluded from the calculation of net loss per share:
Anti-dilutive stock options, restricted stock units, and warrants (in shares)	735			662			735	662
Warrants
Anti-dilutive potential common stock equivalents excluded from the calculation of net loss per share:
Anti-dilutive stock options, restricted stock units, and warrants (in shares)	61			61			61	61

Commitments - Additional Inform

Commitments - Additional Information (Details) ft² in Thousands, $ in Thousands	1 Months Ended	9 Months Ended
	Jan. 31, 2019USD ($)	Sep. 30, 2021USD ($)ft²extension	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)	Jan. 01, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
Area of leased office and laboratory space (in square feet) | ft²		56
Term of contract (in years)					10 years
Number of extensions (in year) | extension		2
Length of extension (in year)		5 years
Annual base rent amount	$ 2,800
Annual rent increase, percent		3.00%
Abatement of base rent amount		$ 500
Operating lease liability					$ 16,900
Lease liability, current portion		1,096		$ 931
Lease liability, net of current portion		14,213		15,065
Operating lease right-of-use assets		8,692		$ 8,968	9,500
Reduction to accrued rent					2,900
Reduction to incentive to lessee					$ 4,500
Operating lease, expense		1,800
Operating lease, payments		$ 2,227	$ 1,685
Weighted average remaining lease term (in years)		7 years 3 months	8 years 3 months
Weighted average discount rate (in percent)		13.08%	13.08%

Open Market Sale Agreement (Det

Open Market Sale Agreement (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019	Mar. 07, 2021	Nov. 05, 2020	Nov. 04, 2020	Mar. 01, 2019
Subsidiary, Sale of Stock
Receivables from shares sold	$ 500,000
ATM
Subsidiary, Sale of Stock
Sale of stock, authorized amount							$ 50,000,000
Sale of stock, commission rate (in percent)	3.00%	3.00%	3.00%				3.00%
Number of shares issued in transaction (in shares)	165,323	2,008,197	36,167
Proceeds from issuance of common stock	$ 2,000,000	$ 22,800,000	$ 400,000
Professional fees		$ 300,000	$ 300,000
ATM | Minimum
Subsidiary, Sale of Stock
Sale of stock, authorized amount						$ 50,000,000
ATM | Maximum
Subsidiary, Sale of Stock
Sale of stock, authorized amount				$ 50,000,000	$ 100,000,000

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event $ in Millions	Nov. 05, 2021USD ($)shares
Subsequent Event
Proceeds from issuance of common stock | $	$ 65
Potential gross proceeds on financing transaction | $	$ 103.1
Series X1 Preferred Stock
Subsequent Event
Number of shares issued in transaction (in shares)	13,997
Number of shares callable by warrant ( in shares)	16,250
Common Stock
Subsequent Event
Number of shares issued in transaction (in shares)	2,253,000
Number of shares per convertible per warrant ( in shares)	1,000