Concert Pharmaceuticals (CNCE) 10-Q 7 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 04, 2019
Document And Entity Information [Abstract]
Entity Current Reporting Status	Yes
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Registrant Name	CONCERT PHARMACEUTICALS, INC.
Entity Central Index Key	0001367920
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		23,841,155

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 33,384,000	$ 17,770,000
Investments, available for sale	88,165,000	135,544,000
Marketable equity securities	5,435,000	7,525,000
Interest receivable	291,000	556,000
Accounts receivable	11,000	15,000
Contract asset (Note 8)	0	16,000,000
Prepaid expenses and other current assets	3,830,000	2,739,000
Total current assets	131,116,000	180,149,000
Property and equipment, net	7,993,000	8,919,000
Restricted cash	1,157,000	1,157,000
Other assets	16,000	0
Income taxes receivable	2,358,000	2,322,000
Operating lease right-of-use assets, long-term (Note 11)	9,317,000	0
Total assets	151,957,000	192,547,000
Current liabilities:
Accounts payable	1,302,000	1,277,000
Accrued expenses and other liabilities	4,434,000	5,669,000
Income taxes payable	0	390,000
Deferred revenue, current portion	7,783,000	1,413,000
Lease liability, current portion (Note 11)	235,000	0
Total current liabilities	13,754,000	8,749,000
Deferred revenue, net of current portion	2,750,000	9,120,000
Deferred lease incentive, net of current portion		4,088,000
Deferred rent, net of current portion		2,850,000
Lease liability, net of current portion (Note 11)	16,190,000	0
Total liabilities	32,694,000	24,807,000
Commitments (Note 11)
Stockholders’ equity:
Preferred stock, $0.001 par value per share; 5,000,000 shares authorized; no shares issued and outstanding in 2019 and 2018, respectively	0	0
Common stock, $0.001 par value per share; 100,000,000 shares authorized; 24,030,711 and 23,518,690 shares issued and 23,841,155 and 23,437,587 outstanding in 2019 and 2018, respectively	23,000	23,000
Additional paid-in capital	293,469,000	284,369,000
Accumulated other comprehensive loss	(35,000)	(137,000)
Accumulated deficit	(174,194,000)	(116,515,000)
Total stockholders’ equity	119,263,000	167,740,000
Total liabilities and stockholders’ equity	$ 151,957,000	$ 192,547,000

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
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)	24,030,711	23,518,690
Common stock, shares outstanding (in shares)	23,841,155	23,437,587

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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating expenses:
Research and development	$ 13,511	$ 11,031	$ 43,797	$ 28,549
General and administrative	4,742	6,320	15,329	17,464
Total operating expenses	18,253	17,351	59,126	46,013
Loss from operations	(18,243)	(17,340)	(58,062)	(35,521)
Investment income	724	703	2,474	2,003
Unrealized gain (loss) on marketable equity securities	334	(732)	(2,091)	(1,359)
Loss before tax provision	(17,185)	(17,369)	(57,679)	(34,877)
Provision for income taxes	0	18	0	298
Net Loss	(17,185)	(17,387)	(57,679)	(35,175)
Other comprehensive income:
Unrealized (loss) gain on investments, available for sale	(39)	87	102	166
Comprehensive loss	$ (17,224)	$ (17,300)	$ (57,577)	$ (35,009)
Net loss per share applicable to common stockholders - basic and diluted (in dollars per share)	$ (0.72)	$ (0.74)	$ (2.43)	$ (1.51)
Weighted-average number of common shares used in net loss per share applicable to common stockholders - basic and diluted (in shares)	23,807	23,421	23,703	23,349
License and Research and Development Revenue
Revenue:
License and research and development revenue	$ 10	$ 11	$ 1,064	$ 10,492

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock	In Treasury	Additional paid-in capital	Accumulated other comprehensive income	Accumulated deficit
Beginning balance (in shares) at Dec. 31, 2017		23,148,000	8,000
Beginning balance at Dec. 31, 2017	$ 196,432	$ 23		$ 273,059	$ (407)	$ (76,243)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		145,000	17,000
Exercise of stock options	658			658
Release of restricted stock units (in shares)		174,000	53,000
Release of restricted stock units	(1,206)			(1,206)
Unrealized gain (loss) on short-term investments	(75)				(75)
Stock-based compensation expense	3,299			3,299
Net loss	(4,463)					(4,463)
Ending balance (in shares) at Mar. 31, 2018		23,467,000	78,000
Ending balance at Mar. 31, 2018	210,397	$ 23		275,810	(482)	(64,954)
Beginning balance (in shares) at Dec. 31, 2017		23,148,000	8,000
Beginning balance at Dec. 31, 2017	196,432	$ 23		273,059	(407)	(76,243)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized gain (loss) on short-term investments	166
Net loss	(35,175)
Ending balance (in shares) at Sep. 30, 2018		23,509,000
Ending balance at Sep. 30, 2018	185,752	$ 23	$ 81	281,636	(241)	(95,666)
Beginning balance (in shares) at Mar. 31, 2018		23,467,000	78,000
Beginning balance at Mar. 31, 2018	210,397	$ 23		275,810	(482)	(64,954)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		25,000
Exercise of stock options	253			253
Unrealized gain (loss) on short-term investments	154				154
Stock-based compensation expense	2,804			2,804
Net loss	(13,325)					(13,325)
Ending balance (in shares) at Jun. 30, 2018		23,492,000	78,000
Ending balance at Jun. 30, 2018	200,283	$ 23		278,867	(328)	(78,279)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		17,000
Exercise of stock options	38		$ 3	38
Unrealized gain (loss) on short-term investments	87				87
Stock-based compensation expense	2,731			2,731
Net loss	(17,387)					(17,387)
Ending balance (in shares) at Sep. 30, 2018		23,509,000
Ending balance at Sep. 30, 2018	185,752	$ 23	$ 81	281,636	(241)	(95,666)
Beginning balance (in shares) at Dec. 31, 2018		23,519,000	81,000
Beginning balance at Dec. 31, 2018	167,740	$ 23		284,369	(137)	(116,515)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		154,000	47,000
Exercise of stock options	805			805
Release of restricted stock units (in shares)		202,000	61,000
Release of restricted stock units	(741)			(741)
Unrealized gain (loss) on short-term investments	97				97
Stock-based compensation expense	2,929			2,929
Exercise of stock warrants (in shares)		71,000
Exercise of stock warrants	1,000			1,000
Offering expenses incurred	(206)			(206)
Net loss	(21,826)					(21,826)
Ending balance (in shares) at Mar. 31, 2019		23,946,000	189,000
Ending balance at Mar. 31, 2019	149,798	$ 23		288,156	(40)	(138,341)
Beginning balance (in shares) at Dec. 31, 2018		23,519,000	81,000
Beginning balance at Dec. 31, 2018	$ 167,740	$ 23		284,369	(137)	(116,515)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)	202,508
Unrealized gain (loss) on short-term investments	$ 102
Net loss	(57,679)
Ending balance (in shares) at Sep. 30, 2019		24,031,000	189,000
Ending balance at Sep. 30, 2019	119,263	$ 23		293,469	(35)	(174,194)
Beginning balance (in shares) at Mar. 31, 2019		23,946,000	189,000
Beginning balance at Mar. 31, 2019	149,798	$ 23		288,156	(40)	(138,341)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		40,000
Exercise of stock options	165			165
Unrealized gain (loss) on short-term investments	44				44
Stock-based compensation expense	2,362			2,362
Net loss	(18,668)					(18,668)
Ending balance (in shares) at Jun. 30, 2019		23,986,000	189,000
Ending balance at Jun. 30, 2019	133,701	$ 23		290,683	4	(157,009)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		9,000
Exercise of stock options	36			36
Unrealized gain (loss) on short-term investments	(39)				(39)
Stock-based compensation expense	2,420			2,420
Proceeds from at-the-market offering (in shares)		36,000
Proceeds from at-the-market offering	330			330
Net loss	(17,185)					(17,185)
Ending balance (in shares) at Sep. 30, 2019		24,031,000	189,000
Ending balance at Sep. 30, 2019	$ 119,263	$ 23		$ 293,469	$ (35)	$ (174,194)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (UNAUDITED) (Parenthetical) $ in Thousands	3 Months Ended
	Sep. 30, 2018USD ($)
Statement of Stockholders' Equity [Abstract]
Unrealized gain on short-term investments, tax	$ 47

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net loss	$ (57,679)	$ (35,175)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,256	875
Stock-based compensation expense	7,711	8,834
Accretion of premiums and discounts on investments	(899)	(234)
Amortization of deferred lease incentive	0	(589)
Non-cash license consideration (Note 8)	0	(10,452)
Other noncash items	0	(46)
Unrealized loss on marketable equity securities	2,090	1,359
Loss on disposal of asset	4	52
Non-cash lease expense (Note 11)	161
Changes in operating assets and liabilities:
Accounts receivable	4	155
Interest receivable	265	115
Prepaid expenses and other current assets	(1,091)	(4)
Contract asset	16,000	0
Other assets	(16)	26
Accounts payable	207	457
Accrued expenses and other liabilities	(827)	(100)
Income taxes receivable	(36)	(77)
Income taxes payable	(390)	372
Deferred rent	0	2,033
Deferred revenue	0	(16)
Operating lease liability (Note 11)	(445)
Net cash used in operating activities	(33,685)	(32,415)
Investing activities
Purchases of property and equipment	(520)	(2,405)
Purchases of investments	(93,326)	(46,120)
Maturities of investments	141,706	93,144
Net cash provided by investing activities	47,860	44,619
Financing activities
Proceeds from exercises of stock options	1,006	934
Proceeds from exercise of warrants	1,000	0
Repurchase of common stock pursuant to share surrender	(741)	(1,206)
Proceeds from at-the-market offering, net of issuance costs	174	0
Net cash provided by (used in) financing activities	1,439	(272)
Net increase in cash and cash equivalents and restricted cash	15,614	11,932
Cash, cash equivalents and restricted cash at beginning of period	18,927	29,222
Cash, cash equivalents and restricted cash at end of period	34,541	41,154
Supplemental cash flow information:
Cash paid for income taxes	453	50
Purchases of property and equipment unpaid at period end	0	99
Public offering costs unpaid at period end	50	0
Cash paid included in measurement of lease liabilities	2,082	0
Tenant improvements paid by landlord	$ 0	$ 4,996

Nature of Business

Nature of Business	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business Concert Pharmaceuticals, Inc., or Concert or the Company, was incorporated on April 12, 2006 as a Delaware corporation with operations based in Lexington, Massachusetts. The Company is a clinical stage biopharmaceutical company that applies its extensive knowledge of deuterium chemistry to discover and develop novel small molecule drugs. The Company’s approach starts with previously studied compounds, including approved drugs, that the Company believes can be improved with deuterium substitution to provide better pharmacokinetic or metabolic properties, enhancing clinical safety, tolerability or efficacy. The Company believes this approach may enable drug discovery and clinical development that is more efficient and less expensive than conventional small molecule drug research and development. The Company’s pipeline includes multiple clinical stage candidates and a number of preclinical compounds that it is currently assessing. The Company had cash and cash equivalents and investments of $121.5 million at September 30, 2019 . The Company believes that its cash and cash equivalents and investments at September 30, 2019 will be sufficient to allow the Company to fund its current operating plan for at least the next twelve months . The Company may pursue additional cash resources through public or private financings, by establishing collaborations with or licensing its technology to other companies and through other arrangements. Since its inception, the Company has generated an accumulated deficit of $174.2 million through September 30, 2019 . The Company's operating results may fluctuate significantly from year to year, depending on the timing and magnitude of clinical trial and other development activities under its current development programs. Substantially all the Company's net losses have resulted from costs incurred in connection with its research and development programs and from general and administrative costs associated with its operations. The Company expects to continue to incur significant expenses and increasing operating losses for at least the next several years. 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. Unless otherwise indicated, all amounts in the following tables are in thousands except share and per share amounts

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	Basis of Presentation and Significant Accounting Policies Basis of Presentation The accompanying 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 three and nine months ended September 30, 2019 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2019 or any other future period. The accompanying condensed consolidated financial statements reflect the accounts of Concert 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 year ended December 31, 2018 filed with the Securities and Exchange Commission, or SEC, on February 28, 2019. 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; lease accounting; income tax expense; stock-based compensation expense; accrued expenses; 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. With the exception of the adoption of Accounting Standards Update, or ASU, 2016-02 during the nine months ended September 30, 2019 discussed in Note 11, 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, 2018. Recently Adopted Accounting Pronouncements In February 2016, the Financial Accounting Standards Board, or FASB, issued ASU 2016-02, Leases , or Topic 842. ASU 2016-02 requires lessees to recognize assets and liabilities on the balance sheet for the rights and obligations created by leases. On January 1, 2019, the Company adopted ASU 2016-02 and all related amendments. For discussion regarding the impact of this accounting pronouncement, refer to Note 11 appearing elsewhere in this Quarterly Report on Form 10-Q. In June 2018, the FASB issued ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting , that expands the scope of Topic 718, Compensation - Stock Compensation , to include share-based payment transactions for acquiring goods and services from nonemployees. ASU 2018-07 provides that an entity should apply the requirements of Topic 718 to nonemployee awards except for certain exemptions specified in the amendment. The Company adopted this new standard effective January 1, 2019, and it did not have a material effect on the consolidated financial statements and related disclosures. In August 2018, the SEC issued Release No. 33-10532 that amends and clarifies certain financial reporting requirements. The principal change to the Company’s financial reporting is the inclusion of the annual disclosure requirement of changes in stockholders’ equity in Rule 3-04 of Regulation S-X to interim periods. The Company adopted this new rule beginning with its first Quarterly Report on Form 10-Q for the quarter ended March 31, 2019. Pending Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses . The new 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. ASU 2016-13 will become effective for the Company for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company is currently evaluating the impact ASU 2016-13 will have on its financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-15, Intangible-Goodwill and Other Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract. The standard aligns the requirements for capitalizing implementation costs in a cloud computing arrangement service contract with the requirements for capitalizing implementation costs incurred for internal-use software. The new guidance also prescribes the balance sheet, income statement and cash flow classification of the capitalized implementation costs and related amortization expense, and requires additional quantitative and qualitative disclosures. ASU 2018-15 is effective for fiscal years beginning after December 15, 2019 and early adoption is permitted. The Company is currently evaluating the impact ASU 2018-15 will have on its financial statements and related disclosures.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
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, 2019 and December 31, 2018 (in thousands) and indicate the level within the fair value hierarchy where each measurement is classified. Level 1 Level 2 Level 3 Total September 30, 2019 Cash equivalents: Money market funds $ 21,253 $ — $ — $ 21,253 U.S. Treasury obligations 4,238 — — 4,238 Investments, available for sale: U.S. Treasury obligations 38,689 — — 38,689 Government agency securities 26,873 22,603 — 49,476 Marketable equity securities: Corporate equity securities (Note 8) 5,435 — — 5,435 Total $ 96,488 $ 22,603 $ — $ 119,091 Level 1 Level 2 Level 3 Total December 31, 2018 Cash equivalents: Money market funds $ 7,643 $ — $ — $ 7,643 U.S. Treasury obligations 1,748 — — 1,748 Investments, available for sale: U.S. Treasury obligations 34,103 746 — 34,849 Government agency securities 64,733 35,962 — 100,695 Marketable equity securities: Corporate equity securities (Note 8) 7,525 — — 7,525 Total $ 115,752 $ 36,708 $ — $ 152,460

Cash, Cash Equivalents, Investm

Cash, Cash Equivalents, Investments and Marketable Equity Securities	9 Months Ended
	Sep. 30, 2019
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. In accordance with ASU 2016-01, 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 income (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 at September 30, 2019 and December 31, 2018: Average maturity Amortized cost Unrealized gains Unrealized losses Fair value September 30, 2019 Cash $ 7,893 $ — $ — $ 7,893 Money market funds 21,253 — — 21,253 U.S. Treasury obligations 52 days 4,238 — — 4,238 Cash and cash equivalents $ 33,384 $ — $ — $ 33,384 U.S. Treasury obligations 169 days 38,683 14 (8 ) 38,689 Government agency securities 88 days 49,443 34 (1 ) 49,476 Investments, available for sale $ 88,126 $ 48 $ (9 ) $ 88,165 September 30, 2019 Acquisition value Unrealized gains Unrealized losses Fair value Marketable equity securities (Note 8) $ 10,451 $ — $ (5,016 ) $ 5,435 Average maturity Amortized cost Unrealized gains Unrealized losses Fair value December 31, 2018 Cash $ 8,379 $ — $ — $ 8,379 Money market funds 7,643 — — 7,643 U.S. Treasury obligations 31 days 1,748 — — 1,748 Cash and cash equivalents $ 17,770 $ — $ — $ 17,770 U.S. Treasury obligations 151 days $ 34,856 $ 2 $ (9 ) $ 34,849 Government agency securities 153 days 100,748 7 (60 ) 100,695 Investments, available for sale $ 135,604 $ 9 $ (69 ) $ 135,544 December 31, 2018 Acquisition value Unrealized gains Unrealized losses Fair value Marketable equity securities (Note 8) $ 10,451 $ — $ (2,926 ) $ 7,525 Although available to be sold to meet operating needs or otherwise (and therefore classified as current assets), securities are generally held through maturity. The cost of securities sold is determined based on the specific identification method for purposes of recording realized gains and losses. During 2019 and 2018, there were no realized gains or losses on sales of investments, and no investments were adjusted other than for temporary declines in fair value.

Restricted Cash

Restricted Cash	9 Months Ended
	Sep. 30, 2019
Cash and Cash Equivalents [Abstract]
Restricted Cash	Restricted Cash Restricted cash as of September 30, 2019 and 2018 is held as collateral for stand-by letters of credit issued by the Company to its landlords in connection with the current and previous leases of the Company's Lexington, Massachusetts facilities. Cash, cash equivalents and restricted cash consisted of the following: September 30, September 30, Cash and cash equivalents $ 33,384 $ 39,597 Restricted cash 1,157 1,557 Total cash, cash equivalents and restricted cash shown in the statements of cash flows $ 34,541 $ 41,154

Accrued Expenses and Other Liab

Accrued Expenses and Other Liabilities	9 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
Accrued Expenses and Other Liabilities	Accrued Expenses and Other Liabilities Accrued expenses and other liabilities consisted of the following: September 30, December 31, Accrued professional fees and other $ 502 $ 672 Employee compensation and benefits 2,245 3,067 Research and development expenses 1,687 1,476 Deferred lease incentive, current portion — 454 $ 4,434 $ 5,669

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
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 United States Internal Revenue Code, or the 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 percent, 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, 2019 , the Company forecasts an ordinary pre-tax loss for the year ended December 31, 2019 and, since it maintains a full valuation allowance on its deferred tax assets, the Company did not record an income tax benefit for the three or nine months ended September 30, 2019 .

Revenue

Revenue	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue	Revenue The Company's revenue is generated through collaborative licensing agreements, patent assignments, and sales of intellectual property. The Company generates its revenue through one segment and the revenue recognized under each of the Company's arrangements during the current and prior period is described below. On January 1, 2018, the Company adopted ASU 2014-19, Revenue from Contracts with Customers , or ASC 606. The Company adopted ASC 606 using the modified retrospective approach. For detailed information regarding the adoption of ASC 606, the impact on its consolidated financial statements and its collaboration arrangements, see Note 2 and Note 12 to the accompanying consolidated financial statements appearing in the Company's Annual Report on Form 10-K filed with the SEC on February 28, 2019. Contract Assets The Company did no t have a contract asset as of September 30, 2019 as compared to $16.0 million as of December 31, 2018. The decrease in the contract asset balance is the result of the receipt of the $16.0 million that had initially been held in escrow for indemnification purposes related to the asset purchase by Vertex Pharmaceuticals, Inc., or Vertex, and was released to the Company in February 2019. Contract Liabilities As of September 30, 2019 and December 31, 2018, the Company had $10.5 million in contract liabilities related to unsatisfied performance obligations as well as variable consideration paid in advance but currently constrained from recognition. The contract liabilities consist of the following deferred revenue: • $7.8 million related to the Company's collaboration with Celgene Corporation, or Celgene, $1.4 million of which is attributable to the CTP-730 program and is currently expected to be recognized as revenue in the next twelve months as the Company satisfies its remaining research and development activities pursuant to mutually agreed upon development plans, and $6.4 million of which is attributable to two additional license programs that the Company will not recognize as revenue unless Celgene exercises its rights with respect to those programs, or in the second quarter of 2020 at such time that Celgene's rights lapse; and • $2.8 million related to a payment received from GlaxoSmithKline, or GSK, that the Company will not recognize as revenue until all repayment obligations lapse. Revenue Arrangements Vertex On March 3, 2017, the Company and Vertex entered into an Asset Purchase Agreement, or the Vertex Agreement, pursuant to which, subject to the satisfaction or waiver of the conditions therein, the Company sold and assigned to Vertex, CTP-656, a deuterated analog of ivacaftor, now known as VX-561, and other cystic fibrosis assets of the Company. On July 25, 2017, or the Vertex Closing Date, the transaction contemplated by the Vertex Agreement closed and Vertex paid the Company $160 million in cash consideration. In addition, Vertex has agreed to pay the Company an aggregate of up to $90 million upon the achievement of certain milestone events. In February 2019, the $16.0 million initially held in escrow was released to the Company. As of December 31, 2018, the Vertex indemnification variable consideration represented a contract asset to be released from escrow 18 months following the Vertex Closing Date and was classified as a current asset in the accompanying consolidated balance sheet. In February 2019, the $16.0 million initially held in escrow was released to the Company. Additionally, the variable consideration related to the regulatory milestone payments are fully constrained due to the uncertainty associated with the achievement of the respective milestones. Accordingly, no contract asset was recorded as of September 30, 2019. Processa On October 4, 2017, the Company entered into a License and Option 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 agreement with Heatwurx, Inc., a public company, creating Processa Pharmaceuticals, Inc., or Processa. On March 21, 2018, the Company entered into an Amendment to the Option, or the Amendment, and a Securities Purchase Agreement, both with Promet and Processa. Pursuant to the 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. The Company is also eligible to receive royalties on worldwide net sales. The Amendment contained one performance obligation: an exclusive, worldwide, royalty-bearing license to develop, commercialize and sublicense 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 within the condensed consolidated statement of operations and comprehensive loss. The 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, 2019 , the Company recognized $2 thousand and $24 thousand in revenue, respectively, related to intellectual property cost reimbursements. For the three months and nine months ended September 30, 2018, the Company recognized $10.5 million in revenue related to the transfer of the license. Cipla The Company entered into a License Agreement, or the Cipla Agreement, on January 16, 2019, or the Cipla Closing Date, with Cipla Technologies LLC, or Cipla, pursuant to which the Company granted Cipla an exclusive, worldwide, royalty-bearing license to develop, manufacture and commercialize CTP-354, a novel GABA A receptor subtype-selective modulator. As consideration for the license, the Company received an upfront payment of $1.0 million . The Cipla Agreement also provides Cipla the option to purchase the Company’s existing inventory of CTP-354 held as of the Effective Date, valued in aggregate at $0.3 million . Additionally, upon the achievement of certain milestone events, Cipla has agreed to pay the Company an aggregate of up to $57.0 million . The first milestone payment the Company may be entitled to receive is $3.0 million when the first IND for the first CTP-354 product goes into effect. Furthermore, the Company is eligible to receive royalties on worldwide net sales of future product sales at defined percentages ranging from the mid-single to high-single digits. The Cipla Agreement contained one performance obligation: an exclusive, worldwide, royalty-bearing license to develop, manufacture, commercialize and sublicense CTP-354, referred to as the Transfer of License Performance Obligation. The Company concluded the option to purchase existing inventory did not provide Cipla a material right, and as such, was treated as a separate contract. The transaction price was determined to be $1.0 million based on the upfront consideration received as of the Cipla Closing Date. As of the Cipla Closing Date, the Transfer of License Performance Obligation was satisfied as the control of CTP-354 transferred to Cipla, the customer. As a result, the full transaction price was recognized as revenue on the Cipla Closing Date. The sale of existing inventory is recognized as goods are transferred to the customer. The arrangement with Cipla contains consideration that is variable based on the customer’s achievement of certain development and regulatory milestones in addition to royalties upon the customer’s commercial success with the licensed product. The next milestone payment the Company may be entitled to receive of $3.0 million related to the first IND for the first CTP-354 product going into effect is considered variable consideration that is fully constrained due to the uncertainty associated with the achievement of the development milestone. The consideration related to royalties is also 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 Cipla and the Company has a present right to payment. The Company did not recognize revenue for the three months ended September 30, 2019 . The Company recognized $1.0 million in revenue associated with the sale of existing inventory and the Transfer of License Performance Obligation for the nine months ended September 30, 2019 .

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation The 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, 2019 , 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 fair value of the underlying common stock on the date of grant, a vesting period of three or four years , and an expiration date no later than ten years from the date of grant. Effective January 1, 2019, an additional 937,503 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, 2019 , there were 1,192,083 shares of common stock available for future award grants 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, 2019 2018 2019 2018 Research and development $ 1,190 $ 1,211 $ 3,728 $ 4,012 General and administrative 1,230 1,520 3,983 4,822 Total stock-based compensation expense $ 2,420 $ 2,731 $ 7,711 $ 8,834 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, 2019 and 2018 reflect the following weighted-average assumptions: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Expected volatility 74.37 % 77.72 % 76.86 % 77.19 % Expected term 6.0 years 6.0 years 6.0 years 6.0 years Risk-free interest rate 1.59 % 2.98 % 2.16 % 2.65 % Expected dividend yield — % — % — % — % For the three and nine months ended September 30, 2019 and 2018, expected volatility was estimated using a weighted-average of the Company's historical volatility of its common stock and the historical volatility of the common stock of a group of similar companies that were publicly traded. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. The following table provides certain information related to the Company's outstanding stock options: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (in thousands, except per share data) Weighted average fair value of options granted, per option $ 6.46 $ 10.42 $ 8.95 $ 17.92 Aggregate grant date fair value of options vested during the period $ 2,234 $ 2,110 $ 7,070 $ 5,839 Total cash received from exercises of stock options $ 36 $ 23 $ 1,006 $ 934 Total intrinsic value of stock options exercised $ 59 $ 187 $ 1,167 $ 2,539 The following is a summary of stock option activity for the nine months ended September 30, 2019 : Number of Option Shares Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (In years) (In thousands) Outstanding at December 31, 2018 3,557,406 $ 15.26 Granted 1,032,250 $ 13.25 Exercised (202,508 ) $ 8.33 Forfeited or expired (184,474 ) $ 18.44 Outstanding at September 30, 2019 4,202,674 $ 14.96 6.99 $ 390 Exercisable at September 30, 2019 2,429,295 $ 13.70 6.03 $ 390 Vested and expected to vest at September 30, 2019 (1) 4,049,442 $ 14.90 6.93 $ 390 (1) This represents the number of vested stock option shares as of September 30, 2019 , plus the number of unvested stock option shares that the Company estimated as of September 30, 2019 would vest, based on the unvested stock option shares at September 30, 2019 and an estimated forfeiture rate of 7% . As of September 30, 2019 , there was $17.4 million of unrecognized 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 2.5 years . Restricted Stock Units On July 6, 2017, the Company granted 0.5 million RSUs, or the 2017 RSU grant, to executives and employees. The awards granted to non-executive employees were service-based, whereas the awards granted to executives were a blend of service-based and performance-based. Assuming all service and performance conditions were achieved, fifty percent of the RSUs would vest on March 31, 2018, and the remaining fifty percent of the RSUs would vest on March 31, 2019. Certain executive awards were subject to the achievement of defined performance criteria prior to March 31, 2018, including the closing of the asset purchase contemplated by the Vertex Agreement and the institution by the Patent Trial and Appeal Board, or PTAB, of the Post Grant Review, or PGR, petition filed by the Company against Incyte Corporation. In January 2018, the PTAB decided not to institute the PGR petition and, as a result, the corresponding performance-based awards did not vest on March 31, 2018. The Company used the accelerated attribution method to recognize expense over the required service period based on its estimate of the number of performance-based awards that vested. For any change in the estimate of the number of performance-based awards that were probable of vesting, the Company cumulatively adjusted compensation expense in the period that the change in estimate was made. On August 15, 2019, or the 2019 RSU grant date, the Company granted 0.4 million RSUs, or the 2019 RSU grant, to certain executives and employees. All awards are service-based and vest ratably over two years . On the first anniversary of the 2019 RSU grant date, thirty-five percent of the RSUs will vest. The remainder of the RSUs will vest on the second anniversary of the 2019 RSU grant date. RSUs are not included in issued and outstanding common stock until the shares are vested and settled. As of September 30, 2019 , all achieved RSUs from the 2017 RSU grant had vested, and no RSUs from the 2019 RSU grant had vested. The fair value of an RSU is measured based on the market price of the underlying common stock as of the date of grant. The following is a summary of RSU activity, including both service-based and performance-based RSUs for the nine months ended September 30, 2019 : Number of RSU Shares Weighted Average Grant Date Fair Value Outstanding at December 31, 2018 228,150 $ 13.87 Granted 412,220 $ 10.27 Released (202,550 ) $ 13.87 Forfeited (25,600 ) $ 13.87 Outstanding at September 30, 2019 412,220 $ 10.27 As of September 30, 2019 , there was $4.0 million of unrecognized compensation cost related to RSUs that are expected to vest. The RSU costs are expected to be recognized over a weighted average remaining vesting period of 1.9 years .

Loss Per Share

Loss Per Share	9 Months Ended
	Sep. 30, 2019
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 common stock equivalents. 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, 2019 2018 2019 2018 (in thousands, except per share amounts) Numerator: Net loss applicable to common stockholders - basic and diluted $ (17,185 ) $ (17,387 ) $ (57,679 ) $ (35,175 ) Denominator: Weighted average shares outstanding - basic and diluted 23,807 23,421 23,703 23,349 Net loss per share applicable to common stockholders - basic and diluted $ (0.72 ) $ (0.74 ) $ (2.43 ) $ (1.51 ) Anti-dilutive potential common stock equivalents excluded from the calculation of net loss per share: Stock options 214 515 290 758 Restricted stock units 410 133 72 214 Warrants 61 132 72 132

Lease

Lease	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Lease	Lease The FASB issued ASU 2016-02, or the leasing standard or ASC 842, in February 2016. ASU 2016-02 requires lessees to recognize assets and liabilities on the balance sheet for the rights and obligations created by all leases with terms of more than 12 months. ASU 2016-02 also requires certain qualitative and quantitative disclosures designed to give financial statement users information on the amount, timing and uncertainty of cash flows arising from leases. The Company adopted ASU 2016-02 effective January 1, 2019. The Company has elected to employ the transitionary relief recently offered by the FASB under ASU 2018-11, and implement the new standard without the restatement of comparative periods’ financial information. ASU 2018-11 also provides for recognizing the effects of applying ASU 2016-02 as a cumulative-effect adjustment to retained earnings as of January 1, 2019; however, no such adjustment was required as of January 1, 2019. The Company has elected to employ the package of practical expedients offered under ASC 842, which allow the Company to not reassess the following: • the presence of a lease in any expired or existing contracts; • the lease classification for any expired or existing leases; and • the initial direct costs for any existing leases. The Company currently leases 55,522 square feet of office and laboratory space, or the Lease, located at 65 Hayden Avenue, Lexington, Massachusetts, or the Premises, which was classified as an operating lease under ASC 840. The Lease is also classified as an operating lease under ASC 842 in accordance with the Company’s election of the practical expedient under ASC 842. Pursuant to the package of practical expedients, the Company will also not reassess initial direct costs for the Premises. Additionally, the Company has made the policy election to adopt the practical expedient to not separate lease components from nonlease components for the right-to-use asset class of office and laboratory space. This policy election results in the Company accounting for the lease component, the use of the Premises and the non-lease components, which include the use of the parking garage, building elevators and HVAC, as a single lease component. The Company occupied the Premises in the third quarter of 2018; however, the Company gained access to the space on January 1, 2018 in order to start making certain tenant improvements. Accordingly, for accounting purposes the lease commencement date was determined to be January 1, 2018 under the prior guidance of ASC 840, and therefore the Company had begun recognizing lease expense as of that date. The Lease term extends ten years following January 1, 2019. The Company is entitled to two five -year options to extend the Lease; however, these options were not included in the calculation of the Lease asset or liability. The Company has elected to employ the provision under ASC 842 to use hindsight with respect to determining the lease term (i.e., consideration of the actual outcome of lease renewals, termination options and purchase options) and in assessing any impairment of right-of-use assets for existing leases. The Company notes no events such as renewals or termination options have occurred with respect to the Lease for the Premises. Therefore, the hindsight practical expedient under ASC 842 has no impact on the accounting term as previously determined under ASC 840. As of September 30, 2019, the remaining lease term for the Premises is 9 years and 3 months . The Lease provides for annual base rent of approximately $2.8 million in the first year following the Base Rent Commencement Date of 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 if the Company is not in default under the Lease). 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; however, the Company has concluded that these payments are not in-substance fixed payments and therefore are not included in the calculation of the related lease liability and asset under ASC 842. The Company recorded the liability associated with the Lease for the Premises at the present value of the lease payments not yet paid, discounted using the discount rate for the Lease established at the commencement date. As the Lease does not provide an implicit rate, the Company had to estimate the incremental borrowing rate, or IBR, as of the commencement date. The IBR is defined under ASC 842 as the rate of interest that the Company would have to pay to borrow on a collateralized basis over a similar term for an amount equal to the lease payments in a similar economic environment. The IBR for the Lease was determined by establishing a credit rating of the Company using the Rank Order Model. Based on the established credit rating, the Company determined a borrowing rate using the Recovery Rate method, adjusted for the risk-free rate, which resulted in an IBR of approximately 13% . The Company used this IBR of 13% to discount the remaining lease payments over the remaining lease term and recorded a lease liability of $16.9 million on January 1, 2019. This lease liability will be 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, 2019 , the Company had a current lease liability of $0.2 million and a non-current lease liability of $16.2 million recorded in its condensed consolidated balance sheets. The Company received an improvement allowance from the Landlord of approximately $5.0 million for certain permitted costs related to the design of Company improvements to the Premises, consisting of normal tenant improvements. The Company is deemed to be the owner of these tenant improvements during the lease term. These $5.0 million of improvements are included in the Company’s property, plant and equipment balances in its condensed consolidated balance sheets as of September 30, 2019 and are depreciated over the shorter of their useful life or the related lease term. On January 1, 2019, the Company recorded a right-of-use asset in the amount $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 (the improvement allowance) in the amount of $4.5 million . The right-of-use asset will be 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, 2019 , the Company had a long-term lease asset of $9.3 million recorded in its condensed consolidated balance sheets. The Company will recognize lease expense, calculated as the remaining cost of the lease allocated over the remaining lease term, on a straight-line basis. Lease expense will be presented as part of continuing operations in the condensed consolidated statement of operations and comprehensive loss. For the nine months ended September 30, 2019 , the Company recognized $1.8 million in lease expense. For the nine months ended September 30, 2019 , the Company paid $2.1 million in rent relating to the Lease. As a payment arising from an operating lease, the $2.1 million will be classified within operating activities in the Condensed Consolidated Statements of Cash Flows. Supplemental cash flow information: For the nine months ended September 30, (in thousands) 2019 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 2,082 Supplemental balance sheet information: For the nine months ended September 30, (in thousands) 2019 2018 Operating lease right-of-use assets $ 9,317 $ — Operating lease liability 16,425 — Weighted average remaining lease term 9.25 10.25 Weighted average discount rate 13.08 % — % Maturities of lease liabilities: For the twelve months ended December 31, (in thousands) 2019 $ 696 * 2020 2,406 2021 2,969 2022 3,058 2023 3,150 Thereafter 17,223 Total lease payments 29,502 Less imputed interest (13,077 ) * Total $ 16,425 * Excludes the nine months ended September 30, 2019

Open Market Sale Agreement

Open Market Sale Agreement	9 Months Ended
	Sep. 30, 2019
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, par value $0.001 per share, having an aggregate offering price of up to $50 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. In addition, the Company has agreed to reimburse certain legal expenses and fees by Jefferies in connection with the offering up to a maximum of $50,000 , in addition to certain ongoing disbursements of Jefferies' counsel. As of November 4, 2019 , the Company has sold 36,167 shares of its common stock in accordance with the ATM Agreement for net proceeds of $0.4 million , after payment of cash commissions of 3.0 percent of the gross proceeds to its sales agent. Additionally, the Company incurred approximately $0.3 million related to legal, accounting and other fees in connection with the ATM Agreement as of September 30, 2019.

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying 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 three and nine months ended September 30, 2019 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2019 or any other future period. The accompanying condensed consolidated financial statements reflect the accounts of Concert 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 year ended December 31, 2018 filed with the Securities and Exchange Commission, or SEC, on February 28, 2019.
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; lease accounting; income tax expense; stock-based compensation expense; accrued expenses; 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. With the exception of the adoption of Accounting Standards Update, or ASU, 2016-02 during the nine months ended September 30, 2019 discussed in Note 11, 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, 2018.
Recently Adopted Accounting Pronouncements and Pending Accounting Pronouncements	Recently Adopted Accounting Pronouncements In February 2016, the Financial Accounting Standards Board, or FASB, issued ASU 2016-02, Leases , or Topic 842. ASU 2016-02 requires lessees to recognize assets and liabilities on the balance sheet for the rights and obligations created by leases. On January 1, 2019, the Company adopted ASU 2016-02 and all related amendments. For discussion regarding the impact of this accounting pronouncement, refer to Note 11 appearing elsewhere in this Quarterly Report on Form 10-Q. In June 2018, the FASB issued ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting , that expands the scope of Topic 718, Compensation - Stock Compensation , to include share-based payment transactions for acquiring goods and services from nonemployees. ASU 2018-07 provides that an entity should apply the requirements of Topic 718 to nonemployee awards except for certain exemptions specified in the amendment. The Company adopted this new standard effective January 1, 2019, and it did not have a material effect on the consolidated financial statements and related disclosures. In August 2018, the SEC issued Release No. 33-10532 that amends and clarifies certain financial reporting requirements. The principal change to the Company’s financial reporting is the inclusion of the annual disclosure requirement of changes in stockholders’ equity in Rule 3-04 of Regulation S-X to interim periods. The Company adopted this new rule beginning with its first Quarterly Report on Form 10-Q for the quarter ended March 31, 2019. Pending Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses . The new 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. ASU 2016-13 will become effective for the Company for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company is currently evaluating the impact ASU 2016-13 will have on its financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-15, Intangible-Goodwill and Other Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract. The standard aligns the requirements for capitalizing implementation costs in a cloud computing arrangement service contract with the requirements for capitalizing implementation costs incurred for internal-use software. The new guidance also prescribes the balance sheet, income statement and cash flow classification of the capitalized implementation costs and related amortization expense, and requires additional quantitative and qualitative disclosures. ASU 2018-15 is effective for fiscal years beginning after December 15, 2019 and early adoption is permitted. The Company is currently evaluating the impact ASU 2018-15 will have on its financial statements and related disclosures.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
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, 2019 and December 31, 2018 (in thousands) and indicate the level within the fair value hierarchy where each measurement is classified. Level 1 Level 2 Level 3 Total September 30, 2019 Cash equivalents: Money market funds $ 21,253 $ — $ — $ 21,253 U.S. Treasury obligations 4,238 — — 4,238 Investments, available for sale: U.S. Treasury obligations 38,689 — — 38,689 Government agency securities 26,873 22,603 — 49,476 Marketable equity securities: Corporate equity securities (Note 8) 5,435 — — 5,435 Total $ 96,488 $ 22,603 $ — $ 119,091 Level 1 Level 2 Level 3 Total December 31, 2018 Cash equivalents: Money market funds $ 7,643 $ — $ — $ 7,643 U.S. Treasury obligations 1,748 — — 1,748 Investments, available for sale: U.S. Treasury obligations 34,103 746 — 34,849 Government agency securities 64,733 35,962 — 100,695 Marketable equity securities: Corporate equity securities (Note 8) 7,525 — — 7,525 Total $ 115,752 $ 36,708 $ — $ 152,460

Cash, Cash Equivalents, Inves_2

Cash, Cash Equivalents, Investments and Marketable Equity Securities (Tables)	9 Months Ended
	Sep. 30, 2019
Cash and Cash Equivalents [Abstract]
Cash Equivalents and Short-term and Long-term Investments	Cash, cash equivalents, available for sale investments, and marketable equity securities included the following at September 30, 2019 and December 31, 2018: Average maturity Amortized cost Unrealized gains Unrealized losses Fair value September 30, 2019 Cash $ 7,893 $ — $ — $ 7,893 Money market funds 21,253 — — 21,253 U.S. Treasury obligations 52 days 4,238 — — 4,238 Cash and cash equivalents $ 33,384 $ — $ — $ 33,384 U.S. Treasury obligations 169 days 38,683 14 (8 ) 38,689 Government agency securities 88 days 49,443 34 (1 ) 49,476 Investments, available for sale $ 88,126 $ 48 $ (9 ) $ 88,165 September 30, 2019 Acquisition value Unrealized gains Unrealized losses Fair value Marketable equity securities (Note 8) $ 10,451 $ — $ (5,016 ) $ 5,435 Average maturity Amortized cost Unrealized gains Unrealized losses Fair value December 31, 2018 Cash $ 8,379 $ — $ — $ 8,379 Money market funds 7,643 — — 7,643 U.S. Treasury obligations 31 days 1,748 — — 1,748 Cash and cash equivalents $ 17,770 $ — $ — $ 17,770 U.S. Treasury obligations 151 days $ 34,856 $ 2 $ (9 ) $ 34,849 Government agency securities 153 days 100,748 7 (60 ) 100,695 Investments, available for sale $ 135,604 $ 9 $ (69 ) $ 135,544 December 31, 2018 Acquisition value Unrealized gains Unrealized losses Fair value Marketable equity securities (Note 8) $ 10,451 $ — $ (2,926 ) $ 7,525

Restricted Cash (Tables)

Restricted Cash (Tables)	9 Months Ended
	Sep. 30, 2019
Cash and Cash Equivalents [Abstract]
Restrictions on Cash and Cash Equivalents	Cash, cash equivalents and restricted cash consisted of the following: September 30, September 30, Cash and cash equivalents $ 33,384 $ 39,597 Restricted cash 1,157 1,557 Total cash, cash equivalents and restricted cash shown in the statements of cash flows $ 34,541 $ 41,154

Accrued Expenses and Other Li_2

Accrued Expenses and Other Liabilities (Tables)	9 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
Accrued Expenses and Other Liabilities	Accrued expenses and other liabilities consisted of the following: September 30, December 31, Accrued professional fees and other $ 502 $ 672 Employee compensation and benefits 2,245 3,067 Research and development expenses 1,687 1,476 Deferred lease incentive, current portion — 454 $ 4,434 $ 5,669

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
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, 2019 2018 2019 2018 Research and development $ 1,190 $ 1,211 $ 3,728 $ 4,012 General and administrative 1,230 1,520 3,983 4,822 Total stock-based compensation expense $ 2,420 $ 2,731 $ 7,711 $ 8,834
Estimated Weighted-Average Assumptions of Options Granted	The weighted average fair value of options granted in the three and nine months ended September 30, 2019 and 2018 reflect the following weighted-average assumptions: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Expected volatility 74.37 % 77.72 % 76.86 % 77.19 % Expected term 6.0 years 6.0 years 6.0 years 6.0 years Risk-free interest rate 1.59 % 2.98 % 2.16 % 2.65 % Expected dividend yield — % — % — % — %
Certain Information Related to 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, 2019 2018 2019 2018 (in thousands, except per share data) Weighted average fair value of options granted, per option $ 6.46 $ 10.42 $ 8.95 $ 17.92 Aggregate grant date fair value of options vested during the period $ 2,234 $ 2,110 $ 7,070 $ 5,839 Total cash received from exercises of stock options $ 36 $ 23 $ 1,006 $ 934 Total intrinsic value of stock options exercised $ 59 $ 187 $ 1,167 $ 2,539
Summary of Stock Option Activity	The following is a summary of stock option activity for the nine months ended September 30, 2019 : Number of Option Shares Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (In years) (In thousands) Outstanding at December 31, 2018 3,557,406 $ 15.26 Granted 1,032,250 $ 13.25 Exercised (202,508 ) $ 8.33 Forfeited or expired (184,474 ) $ 18.44 Outstanding at September 30, 2019 4,202,674 $ 14.96 6.99 $ 390 Exercisable at September 30, 2019 2,429,295 $ 13.70 6.03 $ 390 Vested and expected to vest at September 30, 2019 (1) 4,049,442 $ 14.90 6.93 $ 390 (1) This represents the number of vested stock option shares as of September 30, 2019 , plus the number of unvested stock option shares that the Company estimated as of September 30, 2019 would vest, based on the unvested stock option shares at September 30, 2019 and an estimated forfeiture rate of 7% .
Summary of RSU Activity	The following is a summary of RSU activity, including both service-based and performance-based RSUs for the nine months ended September 30, 2019 : Number of RSU Shares Weighted Average Grant Date Fair Value Outstanding at December 31, 2018 228,150 $ 13.87 Granted 412,220 $ 10.27 Released (202,550 ) $ 13.87 Forfeited (25,600 ) $ 13.87 Outstanding at September 30, 2019 412,220 $ 10.27

Loss Per Share (Tables)

Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
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, 2019 2018 2019 2018 (in thousands, except per share amounts) Numerator: Net loss applicable to common stockholders - basic and diluted $ (17,185 ) $ (17,387 ) $ (57,679 ) $ (35,175 ) Denominator: Weighted average shares outstanding - basic and diluted 23,807 23,421 23,703 23,349 Net loss per share applicable to common stockholders - basic and diluted $ (0.72 ) $ (0.74 ) $ (2.43 ) $ (1.51 ) Anti-dilutive potential common stock equivalents excluded from the calculation of net loss per share: Stock options 214 515 290 758 Restricted stock units 410 133 72 214 Warrants 61 132 72 132

Lease (Tables)

Lease (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Lease, Cost	Supplemental cash flow information: For the nine months ended September 30, (in thousands) 2019 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 2,082
Assets and Liabilities, Lessee	Supplemental balance sheet information: For the nine months ended September 30, (in thousands) 2019 2018 Operating lease right-of-use assets $ 9,317 $ — Operating lease liability 16,425 — Weighted average remaining lease term 9.25 10.25 Weighted average discount rate 13.08 % — %
Lessee, Operating Lease, Liability, Maturity	Maturities of lease liabilities: For the twelve months ended December 31, (in thousands) 2019 $ 696 * 2020 2,406 2021 2,969 2022 3,058 2023 3,150 Thereafter 17,223 Total lease payments 29,502 Less imputed interest (13,077 ) * Total $ 16,425 * Excludes the nine months ended September 30, 2019

Nature of Business - Additional

Nature of Business - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents and investments	$ 121,500
Period of sufficiency of cash resources to fund operating plan	12 months
Accumulated deficit	$ 174,194	$ 116,515

Basis of Presentation and Sig_3

Basis of Presentation and Significant Accounting Policies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2019segment
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, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, cash equivalents	$ 33,384	$ 17,770
Fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	119,091	152,460
Fair value measurements | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	96,488	115,752
Fair value measurements | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	22,603	36,708
Fair value measurements | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	0	0
Shorter maturity | Fair value measurements | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, cash equivalents	21,253	7,643
Shorter maturity | Fair value measurements | Money market funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, cash equivalents	21,253	7,643
Shorter maturity | Fair value measurements | Money market funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, cash equivalents	0	0
Shorter maturity | Fair value measurements | Money market funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, cash equivalents	0	0
Shorter maturity | Fair value measurements | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, cash equivalents		1,748
Shorter maturity | Fair value measurements | U.S. Treasury obligations | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, cash equivalents		1,748
Shorter maturity | Fair value measurements | U.S. Treasury obligations | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, cash equivalents		0
Shorter maturity | Fair value measurements | U.S. Treasury obligations | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, cash equivalents		0
Shorter maturity | Fair value measurements | Government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, cash equivalents	4,238
Shorter maturity | Fair value measurements | Government agency securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, cash equivalents	4,238
Shorter maturity | Fair value measurements | Government agency securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, cash equivalents	0
Shorter maturity | Fair value measurements | Government agency securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, cash equivalents	0
Longer maturity | Fair value measurements | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, investments available-for-sale securities	38,689	34,849
Longer maturity | Fair value measurements | U.S. Treasury obligations | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, investments available-for-sale securities	38,689	34,103
Longer maturity | Fair value measurements | U.S. Treasury obligations | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, investments available-for-sale securities	0	746
Longer maturity | Fair value measurements | U.S. Treasury obligations | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, investments available-for-sale securities	0	0
Longer maturity | Fair value measurements | Government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, investments available-for-sale securities	49,476	100,695
Longer maturity | Fair value measurements | Government agency securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, investments available-for-sale securities	26,873	64,733
Longer maturity | Fair value measurements | Government agency securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, investments available-for-sale securities	22,603	35,962
Longer maturity | Fair value measurements | Government agency securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, investments available-for-sale securities	0	0
Corporate equity securities | Fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, marketable equity securities	5,435	7,525
Corporate equity securities | Fair value measurements | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, marketable equity securities	5,435	7,525
Corporate equity securities | Fair value measurements | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, marketable equity securities	0	0
Corporate equity securities | Fair value measurements | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, marketable equity securities	$ 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	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Cash and Cash Equivalents
Amortized cost, cash and cash equivalents	$ 33,384	$ 17,770	$ 39,597
Fair value, cash and cash equivalent	33,384	17,770
U.S. Treasury obligations
Debt Securities
Amortized cost, investments available for sale	38,683	34,856
Unrealized gains	14	2
Unrealized losses	(8)	(9)
Fair value, available-for-sale securities	38,689	34,849
Government agency securities
Debt Securities
Amortized cost, investments available for sale	49,443	100,748
Unrealized gains	34	7
Unrealized losses	(1)	(60)
Fair value, available-for-sale securities	49,476	100,695
Investments, available for sale
Debt Securities
Amortized cost, investments available for sale	88,126	135,604
Unrealized gains	48	9
Unrealized losses	(9)	(69)
Fair value, available-for-sale securities	88,165	135,544
Marketable equity securities
Marketable Securities
Amortized cost	10,451	10,451
Unrealized gains	0	0
Unrealized losses	(5,016)	(2,926)
Fair value	5,435	7,525
Cash
Cash and Cash Equivalents
Amortized cost, cash and cash equivalents	7,893	8,379
Fair value, cash and cash equivalent	7,893	8,379
Money market funds
Cash and Cash Equivalents
Amortized cost, cash and cash equivalents	21,253	7,643
Fair value, cash and cash equivalent	21,253	7,643
U.S. Treasury obligations
Cash and Cash Equivalents
Amortized cost, cash and cash equivalents	4,238	1,748
Fair value, cash and cash equivalent	$ 4,238	$ 1,748
Measurement Input, Expected Term | U.S. Treasury obligations
Debt Securities
Average maturity	169 days	151 days
Measurement Input, Expected Term | Government agency securities
Debt Securities
Average maturity	88 days	153 days
Measurement Input, Expected Term | U.S. Treasury obligations
Cash and Cash Equivalents
Cash and Cash Equivalents, Term	52 days	31 days

Cash, Cash Equivalents, Inves_4

Cash, Cash Equivalents, Investments and Marketable Equity Securities - Additional Information (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Cash and Cash Equivalents [Abstract]
Debt securities, realized gain	$ 0	$ 0
Debt securities, realized loss	0	0
Equity securities, realized gain	0	0
Equity securities, realized loss	0	0
Other than temporary impairment losses, investments	$ 0	$ 0

Restricted Cash (Details)

Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 33,384	$ 17,770	$ 39,597
Restricted cash	1,157	1,157	1,557
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	$ 34,541	$ 18,927	$ 41,154	$ 29,222

Accrued Expenses and Other Li_3

Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued professional fees and other	$ 502	$ 672
Employee compensation and benefits	2,245	3,067
Research and development expenses	1,687	1,476
Deferred lease incentive, current portion	0	454
Accrued expenses and other liabilities	$ 4,434	$ 5,669

Revenue - Additional Informatio

Revenue - Additional Information (Details)	1 Months Ended	9 Months Ended
	Feb. 28, 2019USD ($)	Sep. 30, 2019USD ($)segment	Dec. 31, 2018USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of segments | segment		1
Contract asset		$ 0	$ 16,000,000
Contract liability		10,500,000	$ 10,500,000
Celgene
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract liability		7,800,000
Celgene | CTP-730
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract liability		1,400,000
Celgene | One of the other additional license programs
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract liability		6,400,000
GSK
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract liability		$ 2,800,000
Indemnification agreement | Disposed of by sale, not discontinued operations | Assets for synthesis and research and development for treating Cystic Fibrosis
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Amount released	$ 16,000,000

Revenue - Vertex (Details)

Revenue - Vertex (Details) - Disposed of by sale, not discontinued operations - Assets for synthesis and research and development for treating Cystic Fibrosis - USD ($)	1 Months Ended
	Feb. 28, 2019	Mar. 03, 2017
Revenue Recognition, Milestone Method [Line Items]
Cash consideration		$ 160,000,000
Indemnification agreement
Revenue Recognition, Milestone Method [Line Items]
Amount released	$ 16,000,000
Contingent consideration asset, After achievement of milestone events
Revenue Recognition, Milestone Method [Line Items]
Contingent consideration receivable		$ 90,000,000

Revenue - Processa (Details)

Revenue - Processa (Details) - Processa - USD ($) $ in Thousands	Mar. 21, 2018	Mar. 19, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue Recognition, Milestone Method [Line Items]
Equity received from sale (in shares)	2,090,301	2,090,301
Allocable arrangement consideration	$ 10,500		$ 2	$ 10,500	$ 10,500	$ 24	$ 10,500

Revenue - Cipla (Details)

Revenue - Cipla (Details) - USD ($)	Jan. 16, 2019	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue			$ 0	$ (16,000)
Cipla
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue	$ 1,000,000
Option to purchase inventory, valuation	300,000
License and research and development revenue	1,000,000	$ 0	$ 1,000,000
Cipla | Achievement of Certain Milestones
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Eligible payments receivable	57,000,000
Cipla | First Milestone
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Eligible payments receivable	$ 3,000,000

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	Aug. 15, 2019	Jan. 01, 2019	Jul. 06, 2017	Sep. 30, 2019
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to unvested options				$ 17.4
Total unrecognized compensation cost, weighted-average recognition period				2 years 6 months 18 days
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years			1 year 10 months 18 days
Number of RSU shares, granted (in shares)	400,000		500,000	412,220
Award vesting percentage	35.00%
Total unrecognized compensation cost related to restricted stock units				$ 4
Restricted stock units | Tranche one
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage			50.00%
Restricted stock units | Tranche two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage			50.00%
2014 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares issued under the plan (in shares)		937,503
Common stock available for future award grant (in shares)				1,192,083
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				3 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				4 years
Awards expiration period				10 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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,420	$ 2,731	$ 7,711	$ 8,834
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,190	1,211	3,728	4,012
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 1,230	$ 1,520	$ 3,983	$ 4,822

Stock-Based Compensation - Esti

Stock-Based Compensation - Estimated Weighted-Average Assumptions of Options Granted (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Payment Arrangement [Abstract]
Expected volatility	74.37%	77.72%	76.86%	77.19%
Expected term	6 years	6 years	6 years	6 years
Risk-free interest rate	1.59%	2.98%	2.16%	2.65%
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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Payment Arrangement [Abstract]
Weighted average grant date fair value of options granted, per option (in dollars per share)	$ 6.46	$ 10.42	$ 8.95	$ 17.92
Aggregate grant date fair value of options vested during the period	$ 2,234	$ 2,110	$ 7,070	$ 5,839
Total cash received from exercises of stock options	36	23	1,006	934
Total intrinsic value of stock options exercised	$ 59	$ 187	$ 1,167	$ 2,539

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2019
Number of Option Shares
Number of options, Outstanding beginning balance (in shares)	3,557,406
Number of options, Granted (in shares)	1,032,250
Number of options, Exercised (in shares)	(202,508)
Number of options, Forfeited or expired (in shares)	(184,474)
Number of options, Outstanding ending balance (in shares)	4,202,674
Number of options, Exercisable (in shares)	2,429,295
Number of options, Vested and expected to vest (in shares)	4,049,442
Weighted Average Exercise Price per Share
Weighted average exercise price per share, Outstanding at beginning of year (in dollars per share)	$ 15.26
Weighted average exercise price per share, Granted (in dollars per share)	13.25
Weighted average exercise price per share, Exercised (in dollars per share)	8.33
Weighted average exercise price per share, Forfeited or expired (in dollars per share)	18.44
Weighted average exercise price per share, Outstanding ending balance (in dollars per share)	14.96
Weighted average exercise price per share, Exercisable (in dollars per share)	13.70
Weighted average exercise price per share, Vested and expected to vest (in dollars per share)	$ 14.90
Weighted Average Remaining Contractual Term (In years)
Weighted average remaining contractual term, Outstanding	6 years 11 months 27 days
Weighted average remaining contractual term, Exercisable	6 years 11 days
Weighted average remaining contractual term, Vested and expected to vest	6 years 11 months 5 days
Aggregate Intrinsic Value
Aggregate intrinsic value, Outstanding	$ 390
Aggregate intrinsic value, Exercisable	390
Aggregate intrinsic value, Vested and expected to vest	$ 390
Stock options
Aggregate Intrinsic Value
Estimated forfeiture rate	7.00%

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of RSU Activity (Details) - Restricted stock units - $ / shares	Aug. 15, 2019	Jul. 06, 2017	Sep. 30, 2019
Number of RSU Shares
Number of RSU shares, Outstanding beginning balance (in shares)			228,150
Number of RSU shares, Granted (in shares)	400,000	500,000	412,220
Number of RSU shares, Released (in shares)			(202,550)
Number of RSU shares, Forfeited (in shares)			(25,600)
Number of RSU shares, Outstanding ending balance (in shares)			412,220
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, Outstanding at beginning of year (in dollars per share)			$ 13.87
Weighted average grant date fair value, Granted (in dollars per share)			10.27
Weighted average grant date fair value, Released (in dollars per share)			13.87
Weighted average grant date fair value, Forfeited (in dollars per share)			13.87
Weighted average grant date fair value, Outstanding at ending of year (in dollars per share)			$ 10.27

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, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Net loss applicable to common stockholders - basic and diluted	$ (17,185)	$ (18,668)	$ (21,826)	$ (17,387)	$ (13,325)	$ (4,463)	$ (57,679)	$ (35,175)
Denominator:
Weighted-average number of common shares used in net loss per share applicable to common stockholders - basic and diluted (in shares)	23,807			23,421			23,703	23,349
Net loss per share applicable to common stockholders - basic and diluted (in dollars per share)	$ (0.72)			$ (0.74)			$ (2.43)	$ (1.51)
Stock options
Anti-dilutive potential common stock equivalents excluded from the calculation of net income (loss) per share:
Anti-dilutive stock options, restricted stock units, and warrants (in shares)	214			515			290	758
Restricted stock units
Anti-dilutive potential common stock equivalents excluded from the calculation of net income (loss) per share:
Anti-dilutive stock options, restricted stock units, and warrants (in shares)	410			133			72	214
Warrants
Anti-dilutive potential common stock equivalents excluded from the calculation of net income (loss) per share:
Anti-dilutive stock options, restricted stock units, and warrants (in shares)	61			132			72	132

Lease - Additional Information

Lease - Additional Information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)ft²extension	Jan. 01, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Area of leased office and laboratory space | ft²	55,522
Term of contract	10 years
Number of extensions | extension	2
Length of extension	5 years
Weighted average remaining lease term	9 years 3 months			10 years 3 months
Annual base rent amount	$ 2,800
Annual rent increase, percent	3.00%
Abatement of base rent amount	$ 500
Discount rate	13.00%
Operating lease liability	$ 16,425	$ 16,900		$ 0
Lease liability, current portion	235		$ 0
Lease liability, net of current portion	16,190		0
Tenant improvement allowance	5,000
Operating lease right-of-use assets	9,317	9,500	$ 0	$ 0
Operating lease, expense	1,800
Operating lease, payments	$ 2,082
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction to accrued rent		2,900
Reduction to incentive to lessee		$ 4,500

Lease - Supplemental Cash Flow

Lease - Supplemental Cash Flow Information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Leases [Abstract]
Operating cash flows from operating leases	$ 2,082

Lease - Supplemental Balance Sh

Lease - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018	Sep. 30, 2018
Leases [Abstract]
Operating lease right-of-use assets	$ 9,317	$ 9,500	$ 0	$ 0
Operating lease liability	$ 16,425	$ 16,900		$ 0
Weighted average remaining lease term	9 years 3 months			10 years 3 months
Weighted average discount rate	13.08%			0.00%

Lease - Lease Maturities (Detai

Lease - Lease Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Sep. 30, 2018
Leases [Abstract]
2019	$ 696
2020	2,406
2021	2,969
2022	3,058
2023	3,150
Thereafter	17,223
Total lease payments	29,502
Less imputed interest	(13,077)
Total	$ 16,425	$ 16,900	$ 0

Open Market Sale Agreement (Det

Open Market Sale Agreement (Details) - USD ($)	Nov. 04, 2019	Nov. 04, 2019	Sep. 30, 2019	Mar. 01, 2019	Dec. 31, 2018
Subsidiary, Sale of Stock [Line Items]
Common stock, par value (in dollars per share)			$ 0.001	$ 0.001	$ 0.001
Sale of stock, authorized amount				$ 50,000,000
Sale of stock, commission rate				3.00%
Legal expense maximum				$ 50,000
Professional fees			$ 300,000
Subsequent Event
Subsidiary, Sale of Stock [Line Items]
Sale of stock, commission rate	3.00%	3.00%
Number of shares issued in transaction (in shares)		36,167
Proceeds from issuance of common stock	$ 400,000

Uncategorized Items - cnce-2019

Label	Element	Value
Accounting Standards Update 2014-09 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 15,752,000
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 15,752,000