Madrigal Pharmaceuticals (MDGL) 10-Q 6 Nov 19 2019 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2019	Nov. 01, 2019
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Entity Interactive Data Current	Yes
Document Transition Report	false
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Period End Date	Sep. 30, 2019
Document Fiscal Period Focus	Q3
Entity Registrant Name	MADRIGAL PHARMACEUTICALS, INC.
Entity Central Index Key	0001157601
Entity File Number	001-33277
Entity Tax Identification Number	04-3508648
Entity Incorporation, State or Country Code	DE
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Address, Address Line One	Four Tower Bridge
Entity Address, Address Line Two	200 Barr Harbor Drive
Entity Address, Address Line Three	Suite 200
Entity Address, City or Town	West Conshohocken
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19428
City Area Code	267
Local Phone Number	824-2827
Trading Symbol	MDGL
Security Exchange Name	NASDAQ
Title of 12(b) Security	Common Stock, $0.0001 Par Value Per Share
Entity Common Stock, Shares Outstanding		15,429,154

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 89,486	$ 57,379
Marketable securities	364,124	426,339
Prepaid expenses and other current assets	1,712	1,483
Total current assets	455,322	485,201
Property and equipment, net	181	227
Right-of-use asset	751
Total assets	456,254	485,428
Current liabilities:
Accounts payable	773	2,487
Accrued expenses	14,381	5,957
Lease liability, current	310
Total current liabilities	15,464	8,444
Long-term liabilities:
Lease liability, long term	441
Total long term liabilities	441
Total liabilities	15,905	8,444
Stockholders' equity:
Preferred stock, par value $0.0001 per share authorized: 5,000,000 shares at September 30, 2019 and December 31, 2018; 1,969,797 shares issued and outstanding at September 30, 2019 and December 31, 2018
Common stock, par value $0.0001 per share authorized: 200,000,000 at September 30, 2019 and December 31, 2018; 15,429,154 and 15,409,023 shares issued and outstanding at September 30, 2019 and December 31, 2018, respectively	2	2
Additional paid-in-capital	635,535	616,573
Accumulated other comprehensive gain (loss)	292	(319)
Accumulated deficit	(195,480)	(139,272)
Total stockholders' equity	440,349	476,984
Total liabilities and stockholders' equity	$ 456,254	$ 485,428

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Condensed Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	1,969,797	1,969,797
Preferred stock, shares outstanding	1,969,797	1,969,797
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	15,429,154	15,409,023
Common stock, shares outstanding	15,429,154	15,409,023

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ 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	$ 19,447	$ 6,211	$ 47,414	$ 16,518
General and administrative	4,748	5,122	17,604	9,710
Total operating expenses	24,195	11,333	65,018	26,228
Loss from operations	(24,195)	(11,333)	(65,018)	(26,228)
Interest income	2,766	2,821	8,810	4,692
Other income				200
Net loss	$ (21,429)	$ (8,512)	$ (56,208)	$ (21,336)
Net loss per common share:
Basic and diluted net loss per common share (in dollars per share)	$ (1.39)	$ (0.56)	$ (3.65)	$ (1.46)
Basic and diluted weighted average number of common shares outstanding	15,415,096	15,307,872	15,383,034	14,610,809

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Consolidated Statements of Comprehensive Loss
Net Loss	$ (21,429)	$ (8,512)	$ (56,208)	$ (21,336)
Other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale securities	(193)	(100)	611	(112)
Comprehensive loss	$ (21,622)	$ (8,612)	$ (55,597)	$ (21,448)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common stock	Additional paid-in Capital	Accumulated other comprehensive income (loss)	Accumulated deficit
Balance at Dec. 31, 2017	$ 182,259		$ 1	$ 288,750	$ (31)	$ (106,461)
Balance (in shares) at Dec. 31, 2017		1,969,797	14,227,634
Increase (Decrease) in Stockholders' Equity
Exercise of common stock options	265			265
Exercise of common stock options (in shares)			23,092
Compensation expense related to stock options for services	1,167			1,167
Unrealized gain on marketable securities	(143)				(143)
Net loss	(6,364)					(6,364)
Balance at Mar. 31, 2018	177,184		$ 1	290,182	(174)	(112,825)
Balance (in shares) at Mar. 31, 2018		1,969,797	14,250,726
Balance at Dec. 31, 2017	182,259		$ 1	288,750	(31)	(106,461)
Balance (in shares) at Dec. 31, 2017		1,969,797	14,227,634
Increase (Decrease) in Stockholders' Equity
Unrealized gain on marketable securities	(112)
Net loss	(21,336)
Balance at Sep. 30, 2018	482,907		$ 2	610,845	(143)	(127,797)
Balance (in shares) at Sep. 30, 2018		1,969,797	15,393,309
Balance at Mar. 31, 2018	177,184		$ 1	290,182	(174)	(112,825)
Balance (in shares) at Mar. 31, 2018		1,969,797	14,250,726
Increase (Decrease) in Stockholders' Equity
Exercise of common stock options	1,185			1,185
Exercise of common stock options (in shares)			35,078
Issuance of common shares in equity offering, excluding related parties, net of transaction costs	311,825		$ 1	311,824
Issuance of common shares in equity offering, excluding related parties, net of transaction costs (in shares)			1,079,580
Compensation expense related to stock options for services	2,227			2,227
Unrealized gain on marketable securities	131				131
Net loss	(6,460)					(6,460)
Balance at Jun. 30, 2018	486,092		$ 2	605,418	(43)	(119,285)
Balance (in shares) at Jun. 30, 2018		1,969,797	15,365,384
Increase (Decrease) in Stockholders' Equity
Exercise of common stock options	451			451
Exercise of common stock options (in shares)			27,925
Compensation expense related to stock options for services	4,976			4,976
Unrealized gain on marketable securities	(100)				(100)
Net loss	(8,512)					(8,512)
Balance at Sep. 30, 2018	482,907		$ 2	610,845	(143)	(127,797)
Balance (in shares) at Sep. 30, 2018		1,969,797	15,393,309
Balance at Dec. 31, 2018	$ 476,984		$ 2	616,573	(319)	(139,272)
Balance (in shares) at Dec. 31, 2018	15,409,023	1,969,797	15,409,023
Increase (Decrease) in Stockholders' Equity
Exercise of common stock options	$ 83			83
Exercise of common stock options (in shares)			8,041
Compensation expense related to stock options for services	6,022			6,022
Unrealized gain on marketable securities	497				497
Net loss	(15,080)					(15,080)
Balance at Mar. 31, 2019	468,506		$ 2	622,678	178	(154,352)
Balance (in shares) at Mar. 31, 2019		1,969,797	15,417,064
Balance at Dec. 31, 2018	$ 476,984		$ 2	616,573	(319)	(139,272)
Balance (in shares) at Dec. 31, 2018	15,409,023	1,969,797	15,409,023
Increase (Decrease) in Stockholders' Equity
Unrealized gain on marketable securities	$ 611
Net loss	(56,208)
Balance at Sep. 30, 2019	$ 440,349		$ 2	635,535	292	(195,480)
Balance (in shares) at Sep. 30, 2019	15,429,154	1,969,797	15,429,154
Balance at Mar. 31, 2019	$ 468,506		$ 2	622,678	178	(154,352)
Balance (in shares) at Mar. 31, 2019		1,969,797	15,417,064
Increase (Decrease) in Stockholders' Equity
Exercise of common stock options	117			117
Exercise of common stock options (in shares)			9,233
Compensation expense related to stock options for services	7,755			7,755
Unrealized gain on marketable securities	307				307
Net loss	(19,699)					(19,699)
Balance at Jun. 30, 2019	456,986		$ 2	630,550	485	(174,051)
Balance (in shares) at Jun. 30, 2019		1,969,797	15,426,297
Increase (Decrease) in Stockholders' Equity
Exercise of common stock options	35			35
Exercise of common stock options (in shares)			2,857
Compensation expense related to stock options for services	4,950			4,950
Unrealized gain on marketable securities	(193)				(193)
Net loss	(21,429)					(21,429)
Balance at Sep. 30, 2019	$ 440,349		$ 2	$ 635,535	$ 292	$ (195,480)
Balance (in shares) at Sep. 30, 2019	15,429,154	1,969,797	15,429,154

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net loss	$ (56,208)	$ (21,336)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	18,727	8,370
Depreciation and amortization expense	84	71
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(229)	(281)
Accounts payable	(1,714)	(898)
Accrued expense	8,424	(2,514)
Accrued interest, net of interest received on maturity of investments	1,574	(2,654)
Net cash used in operating activities	(29,342)	(19,242)
Cash flows from investing activities:
Purchases of marketable securities	(407,073)	(524,935)
Sales and maturities of marketable securities	468,325	119,885
Purchases of property and equipment, net of disposals	(38)	(14)
Net cash provided by (used in) investing activities	61,214	(405,064)
Cash flows from financing activities:
Proceeds from issuances of stock, excluding related parties, net of transaction costs		311,825
Proceeds from the exercise of common stock options	235	1,900
Net cash provided by financing activities	235	313,725
Net increase (decrease) in cash and cash equivalents	32,107	(110,581)
Cash and cash equivalents at beginning of period	57,379	148,627
Cash and cash equivalents at end of period	89,486	$ 38,046
Supplemental disclosure of cash flow information:
Obtaining a right-of-use asset in exchange for a lease liability	$ 900

Organization, Business and Basi

Organization, Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2019
Organization, Business and Basis of Presentation
Organization, Business and Basis of Presentation	1. Organization, Business, and Basis of Presentation Organization and Business Madrigal Pharmaceuticals, Inc. (the “Company” or “Madrigal”) is a clinical-stage pharmaceutical company developing novel, high-quality, small-molecule drugs addressing major unmet needs in cardiovascular, metabolic, and liver diseases. The Company’s lead compound, MGL-3196 non-alcoholic non-alcoholic Madrigal was originally incorporated as a private company (“Private Madrigal”) on August 19, 2011 and operations commenced in September 2011. On July 22, 2016, Private Madrigal completed a reverse merger (the “Merger”) into Synta Pharmaceuticals Corp. (“Synta”). Upon the consummation of the Merger, the historical financial statements of Private Madrigal became the Company’s historical financial statements. Basis of Presentation Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) have been condensed or omitted. Accordingly, the unaudited condensed consolidated financial statements do not include all information and footnotes required by GAAP for complete annual financial statements. However, we believe that the disclosures included in these financial statements are adequate to make the information presented not misleading. The unaudited condensed financial statements, in the opinion of management, reflect all adjustments, which include normal recurring adjustments, necessary for a fair statement of such interim results. The interim results are not necessarily indicative of the results that we will have for the full year ending December 31, 2019 or any subsequent period. These unaudited condensed financial statements should be read in conjunction with the audited consolidated financial statements and the notes to those statements for the year ended December 31, 2018.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Principle of Consolidation The consolidated financial statements include the financial statements of the Company and its wholly owned subsidiaries. All significant intercompany balances have been eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect certain reported amounts of assets and liabilities, and the reported amounts of revenues and expenses during the reporting periods. The Company bases its estimates on historical experience and various other assumptions that management believes to be reasonable under the circumstances. Changes in estimates are recorded in the period in which they become known. Actual results could ​​​​​​​differ from those estimates. Cash and Cash Equivalents The Company considers all highly liquid investments with original maturities of three months or less at the date of purchase to be cash equivalents. The Company maintains its cash in bank accounts, the balance of which, at times, exceeds Federal Deposit Insurance Corporation insured limits. The primary objective of the Company’s investment activities is to preserve its capital for the purpose of funding operations and the Company does not enter into investments for trading or speculative purposes. The Company’s cash is deposited in highly rated financial institutions in the United States. The Company invests in money market funds and high-grade, commercial paper and corporate bonds, which management believes are subject to minimal credit and market risk. Marketable Securities Marketable securities consist of investments in high-grade corporate obligations and government and government agency obligations that are classified as available-for-sale. The Company adjusts the cost of available-for-sale available-for-sale Marketable securities are stated at fair value, including accrued interest, with their unrealized gains and losses included as a component of accumulated other comprehensive income or loss, which is a separate component of stockholders’ equity. The fair value of these securities is based on quoted prices and observable inputs on a recurring basis. Realized gains and losses are determined on the specific identification method. During the three and nine months ended September 30, 2019 and 2018, the Company did not have any realized gains or losses on marketable securities. Fair Value of Financial Instruments The carrying amounts of the Company’s financial instruments, which include cash equivalents, and marketable securities, approximate their fair values. The fair value of the Company’s financial instruments reflects the amounts that would be received upon sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value hierarchy has the following three levels: Level 1—quoted prices in active markets for identical assets and liabilities. Level 2—observable inputs other than Level 1 inputs. Examples of Level 2 inputs include quoted prices in active markets for similar assets or liabilities and quoted prices for identical assets or liabilities in markets that are not active. Level 3—unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. Financial assets and liabilities are classified in their entirety within the fair value hierarchy based on the lowest level of input that is significant to the fair value measurement. The Company measures the fair value of its marketable securities by taking into consideration valuations obtained from third-party pricing sources. The pricing services utilize industry standard valuation models, including both income and market based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker-dealer quotes on the same or similar securities, issuer credit spreads, benchmark securities and other observable inputs. As of September 30, 2019, the Company’s financial assets valued based on Level 1 inputs consisted of cash and cash equivalents in a money market fund and its financial assets valued based on Level 2 inputs consisted of high-grade corporate bonds and commercial paper. During the three and nine months ended September 30, 2019 and 2018, the Company did not have any transfers of financial assets between Levels 1 and 2. As of September 30, 2019 and December 31, 2018, the Company did not have any financial liabilities that were recorded at fair value on a recurring basis on the balance sheet. Research and Development Costs Research and development costs are expensed as incurred. Research and development costs are comprised of costs incurred in performing research and development activities, including internal costs (including stock-based compensation), costs for consultants, milestone payments under licensing agreements, and other costs associated with the Company’s preclinical and clinical programs. In particular, the Company has conducted safety studies in animals, optimized and implemented the manufacturing of our drug, and conducted Phase 1-3 Patents Costs to secure and defend patents are expensed as incurred and are classified as general and administrative expense in the Company’s consolidated statements of operations. Stock-Based Compensation The Company recognizes stock-based compensation expense based on the grant date fair value of stock options granted to employees, officers, and directors. The Company uses the Black-Scholes option pricing model to determine the grant date fair value as management believes it is the most appropriate valuation method for its option grants. The Black-Scholes model requires inputs for risk-free interest rate, dividend yield, volatility and expected lives of the options. The expected lives for options granted represent the period of time that options granted are expected to be outstanding. The Company uses the simplified method for determining the expected lives of options. Expected volatility is based upon an industry estimate or blended rate including the Company’s historical trading activity. The risk-free rate for periods within the expected life of the option is based on the U.S. Treasury yield curve in effect at the time of the grant. The Company estimates the forfeiture rate based on historical data. This analysis is re-evaluated Certain of the employee stock options granted by the Company are structured to qualify as incentive stock options (“ISOs”). Under current tax regulations, the Company does not receive a tax deduction for the issuance, exercise or disposition of ISOs if the employee meets certain holding requirements. If the employee does not meet the holding requirements, a disqualifying disposition occurs, at which time the Company may receive a tax deduction. The Company does not record tax benefits related to ISOs unless and until a disqualifying disposition is reported. In the event of a disqualifying disposition, the entire tax benefit is recorded as a reduction of income tax expense. The Company has not recognized any income tax benefit for its share-based compensation arrangements due to the fact that the Company does not believe it is more likely than not it will realize the related deferred tax assets. Income Taxes The Company uses the asset and liability method to account for income taxes. Deferred tax assets and liabilities are determined based on the expected future tax consequences of temporary differences between the Company’s financial statement carrying amounts and the tax basis of assets and liabilities using enacted tax rates expected to be in effect in the years in which the differences are expected to reverse. The Company currently maintains a 100% valuation allowance on its deferred tax assets. Comprehensive Loss Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner Basic and Diluted Loss Per Common Share Basic net loss per share is computed using the weighted average number of common shares outstanding during the period, excluding restricted stock that has been issued but is not yet vested. Diluted net loss per common share is computed using the weighted average number of common shares outstanding and the weighted average dilutive potential common shares outstanding using the treasury stock method. However, for the nine months ended September 30, 2019 and 2018, diluted net loss per share is the same as basic net loss per share because the inclusion of weighted average shares of unvested restricted common stock, common stock issuable upon the exercise of stock options, and common stock issuable upon the conversion of preferred stock would be anti-dilutive. The following table summarizes outstanding securities not included in the computation of diluted net loss per common share, as their inclusion would be anti-dilutive: Three and Nine Months Ended September 30, 2019 2018 Common Stock Options 1,461,237 1,123,582 Unvested Restricted Common Stock — 52,063 Preferred Stock 1,969,797 1,969,797 Recent Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, right-of-use ASU 2016-02 2016-02 8

Liquidity and Uncertainties

Liquidity and Uncertainties	9 Months Ended
	Sep. 30, 2019
Liquidity and Uncertainties
Liquidity and Uncertainties	3. Liquidity and Uncertainties The Company is subject to risks common to development stage companies in the biopharmaceutical industry including, but not limited to, uncertainty of product development and commercialization, dependence on key personnel, uncertainty of market acceptance of products and product reimbursement, product liability, uncertain protection of proprietary technology, potential inability to raise additional financing necessary for development and commercialization, and compliance with the U.S. Food and Drug Administration and other government regulations. The Company has incurred losses since inception, including approximately $56.2 million for the nine months ended September 30, 2019, resulting in an accumulated deficit of approximately $195.5 million as of September 30, 2019. Management expects to incur losses for the foreseeable future. To date, the Company has funded its operations primarily through the issuance of convertible debt, the proceeds from the Merger on July 22, 2016, and proceeds from sales of the Company’s equity securities. The Company believes that its cash, cash equivalents and marketable securities at September 30, 2019 will be sufficient to fund operations past one year from the issuance of these financial statements. To meet its future capital needs, the Company intends to raise additional capital through debt or equity financings, collaborations, partnerships or other strategic transactions. However, there can be no assurance that the Company will be able to complete any such transactions on acceptable terms or otherwise. The inability of the Company to obtain sufficient funds on acceptable terms when needed could have a material adverse effect on the Company’s business, results of operations and financial condition. The Company has the ability to delay certain research activities and related clinical expenses if necessary due to liquidity concerns until a date when those concerns are relieved.

Cash, Cash Equivalents and Mark

Cash, Cash Equivalents and Marketable Securities	9 Months Ended
	Sep. 30, 2019
Cash, Cash Equivalents and Marketable Securities
Cash, Cash Equivalents and Marketable Securities	4. Cash, Cash Equivalents and Marketable Securities A summary of cash, cash equivalents and available-for-sale September 30, 2019 Cost Unrealized Unrealized Fair value Cash and cash equivalents: Cash (Level 1) $ 1,975 $ — $ — $ 1,975 Money market funds (Level 1) 87,511 — — 87,511 Corporate debt securities due within 3 months of date of purchase (Level 2) — — — — Total cash and cash equivalents 89,486 — — 89,486 Marketable securities: Corporate debt securities due within 1 year of date of purchase (Level 2) 278,707 264 (9 ) 278,962 Corporate debt securities due within 1 to 2 years of date of purchase (Level 2) 85,125 59 (22 ) 85,162 Total cash, cash equivalents and marketable securities $ 453,318 $ 323 $ (31 ) $ 453,610 December 31, 2018 Cost Unrealized Unrealized Fair value Cash and cash equivalents: Cash (Level 1) $ 2,004 $ — $ — $ 2,004 Money market funds (Level 1) 43,401 — — 43,401 Corporate debt securities due within 3 months of date of purchase (Level 2) 11,974 — — 11,974 Total cash and cash equivalents 57,379 — — 57,379 Marketable securities: Corporate debt securities due within 1 year of date of purchase (Level 2) 426,658 14 (333 ) 426,339 Total cash, cash equivalents and marketable securities $ 484,037 $ 14 $ (333 ) $ 483,718

Accrued Liabilities

Accrued Liabilities	9 Months Ended
	Sep. 30, 2019
Accrued Liabilities, Current [Abstract]
Accrued Liabilities	5. Accrued Liabilities Accrued liabilities as of September 30, 2019 and December 31, 2018 consisted of the following (in thousands): September 30, December 31, Accrued contract research costs $ 7,882 $ 571 Compensation and benefits 1,936 1,797 Other 4,563 3,589 $ 14,381 $ 5,957

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2019
Stockholders' Equity
Stockholders' Equity	6 Common Stock Each common stockholder is entitled to one vote for each share of common stock held. The common stock will vote together with all other classes and series of stock of the Company as a single class on all actions to be taken by the Company’s stockholders. Each share of common stock is entitled to receive dividends, as and when declared by the Company’s board of directors. The Company has never declared cash dividends on its common stock and does not expect to do so in the foreseeable future. Preferred Stock The Series A Preferred Stock has a par value of $0.0001 per share and is convertible into shares of the common stock at a one-to-one subject to adjustment as provided in the Certificate of Designation of Preferences, Rights and Limitations of Series A Convertible Preferred Stock, that the Company filed with the Secretary of State of the State of Delaware on June 21, 2017 (the “Series A Certificate”). The terms of the Series A Preferred Stock are set forth in the Series A Certificate. winding-up as-if-converted-to as-converted June 2018 Registered Offering of Common Stock In June 2018, the Company entered into an underwriting agreement with Goldman Sachs & Co. LLC, as representative of the several underwriters named therein (the “June 2018 Underwriters”), relating to an underwritten public offering (the “June 2018 Offering”) of 1,079,580 shares of the Company’s common stock, including 95,973 shares of the Company’s common stock purchased by the June 2018 Underwriters pursuant to a 30-day

Stock-based Compensation

Stock-based Compensation	9 Months Ended
	Sep. 30, 2019
Stock-based Compensation
Stock-based Compensation	7 The 2015 Stock Plan, as amended, is our primary plan through which equity ​​​​​​​based grants are awarded. We ceased making new awards under the 2006 Stock Plan upon adoption of the 2015 Stock Plan. The 2015 Stock Plan provides for the grant of incentive stock options, non-statutory The following table summarizes stock option activity during the nine months ended September 30, 2019: Shares Weighted Outstanding at January 1, 2019 1,132,618 $ 48.52 Options granted 369,500 119.29 Options exercised (20,131 ) 11.67 Options cancelled (20,750 ) 173.79 Outstanding at September 30, 2019 1,461,237 $ 65.15 Exercisable at September 30, 2019 922,149 $ 40.55 The total cash received by the Company as a result of stock option exercises was $0.2 million and $1.9 million, respectively, for the nine months ended September 30, 2019 and 2018. The weighted-average grant date fair values, based on the Black-Scholes option model, of options granted during the nine months ended September 30, 2019 and 2018 were $91.65 and $136.43, respectively. Restricted Common Stock The Company’s share-based compensation plan provides for awards of restricted shares of common stock to employees, officers, directors and consultants to the Company. Restricted stock awards are subject to forfeiture if employment or service terminates during the prescribed retention period. Restricted shares vest over the service period. The following table summarizes unvested restricted share activity during the nine months ended September 30, 2019: Shares Weighted Outstanding at January 1, 2019 52,063 $ 9.45 Vested (52,063 ) 9.45 Outstanding at September 30, 2019 — $ — Stock-Based Compensation Expense Stock-based compensation expense during the three and nine months ended September 30, 2019 and 2018 was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Stock-based compensation expense by type of award: Stock options $ 4,922 $ 4,852 $ 18,455 $ 8,002 Restricted stock 28 124 272 368 Total stock-based compensation expense $ 4,950 $ 4,976 $ 18,727 $ 8,370 Effect of stock-based compensation expense by line item: Research and development $ 2,404 $ 1,179 $ 6,647 $ 2,287 General and administrative 2,546 3,797 12,080 6,083 Total stock-based compensation expense included in net loss $ 4,950 $ 4,976 $ 18,727 $ 8,370 Unrecognized stock-based compensation expense as of September 30, 2019 was as follows (in thousands): Unrecognized Weighted Stock options $ 35,429 2.86 Restricted stock — — Total $ 35,429 2.86

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases
Leases	8 In 2019, the Company entered into an operating lease for office space. As described within Note 2, we adopted ASU 2016-02, non-cancelable Future minimum payments under the Company’s operating leases related to the ROU asset and lease liability as of September 30, 2019 was as follows (in thousand): Operating Leases 2019 $ 89 2020 363 2021 371 2022 31 Thereafter — Total minimum payments $ 854 Less: imputed interest 103 Present value of lease liabilities $ 751 As of September 30, 2019, the weighted average remaining operating lease term was 2.3 years and the weighted average discount rate used to determine the operating lease liabilities was 5.5%. Operating lease costs were $93 thousand and $267 thousand, short-term lease costs were $23 thousand and $138 thousand, and there were no variable lease costs for the three and nine months ended September 30, 2019, respectively.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies
Commitments and Contingencies	9 The Company has a Research, Development and Commercialization Agreement with Hoffmann-La The agreement requires future milestone payments to Roche. In 2019, the Company commenced a Phase 3 study in Non-Alcoholic MGL-3196 The Company has entered into customary contractual arrangements and letters of intent in preparation for and in support of the Phase 3 clinical trials.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Summary of Significant Accounting Policies
Principle of Consolidation	Principle of Consolidation The consolidated financial statements include the financial statements of the Company and its wholly owned subsidiaries. All significant intercompany balances have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect certain reported amounts of assets and liabilities, and the reported amounts of revenues and expenses during the reporting periods. The Company bases its estimates on historical experience and various other assumptions that management believes to be reasonable under the circumstances. Changes in estimates are recorded in the period in which they become known. Actual results could ​​​​​​​differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with original maturities of three months or less at the date of purchase to be cash equivalents. The Company maintains its cash in bank accounts, the balance of which, at times, exceeds Federal Deposit Insurance Corporation insured limits. The primary objective of the Company’s investment activities is to preserve its capital for the purpose of funding operations and the Company does not enter into investments for trading or speculative purposes. The Company’s cash is deposited in highly rated financial institutions in the United States. The Company invests in money market funds and high-grade, commercial paper and corporate bonds, which management believes are subject to minimal credit and market risk.
Marketable Securities	Marketable Securities Marketable securities consist of investments in high-grade corporate obligations and government and government agency obligations that are classified as available-for-sale. The Company adjusts the cost of available-for-sale available-for-sale Marketable securities are stated at fair value, including accrued interest, with their unrealized gains and losses included as a component of accumulated other comprehensive income or loss, which is a separate component of stockholders’ equity. The fair value of these securities is based on quoted prices and observable inputs on a recurring basis. Realized gains and losses are determined on the specific identification method. During the three and nine months ended September 30, 2019 and 2018, the Company did not have any realized gains or losses on marketable securities.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of the Company’s financial instruments, which include cash equivalents, and marketable securities, approximate their fair values. The fair value of the Company’s financial instruments reflects the amounts that would be received upon sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value hierarchy has the following three levels: Level 1—quoted prices in active markets for identical assets and liabilities. Level 2—observable inputs other than Level 1 inputs. Examples of Level 2 inputs include quoted prices in active markets for similar assets or liabilities and quoted prices for identical assets or liabilities in markets that are not active. Level 3—unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. Financial assets and liabilities are classified in their entirety within the fair value hierarchy based on the lowest level of input that is significant to the fair value measurement. The Company measures the fair value of its marketable securities by taking into consideration valuations obtained from third-party pricing sources. The pricing services utilize industry standard valuation models, including both income and market based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker-dealer quotes on the same or similar securities, issuer credit spreads, benchmark securities and other observable inputs. As of September 30, 2019, the Company’s financial assets valued based on Level 1 inputs consisted of cash and cash equivalents in a money market fund and its financial assets valued based on Level 2 inputs consisted of high-grade corporate bonds and commercial paper. During the three and nine months ended September 30, 2019 and 2018, the Company did not have any transfers of financial assets between Levels 1 and 2. As of September 30, 2019 and December 31, 2018, the Company did not have any financial liabilities that were recorded at fair value on a recurring basis on the balance sheet.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. Research and development costs are comprised of costs incurred in performing research and development activities, including internal costs (including stock-based compensation), costs for consultants, milestone payments under licensing agreements, and other costs associated with the Company’s preclinical and clinical programs. In particular, the Company has conducted safety studies in animals, optimized and implemented the manufacturing of our drug, and conducted Phase 1-3
Patents	Patents Costs to secure and defend patents are expensed as incurred and are classified as general and administrative expense in the Company’s consolidated statements of operations.
Stock-Based Compensation	Stock-Based Compensation The Company recognizes stock-based compensation expense based on the grant date fair value of stock options granted to employees, officers, and directors. The Company uses the Black-Scholes option pricing model to determine the grant date fair value as management believes it is the most appropriate valuation method for its option grants. The Black-Scholes model requires inputs for risk-free interest rate, dividend yield, volatility and expected lives of the options. The expected lives for options granted represent the period of time that options granted are expected to be outstanding. The Company uses the simplified method for determining the expected lives of options. Expected volatility is based upon an industry estimate or blended rate including the Company’s historical trading activity. The risk-free rate for periods within the expected life of the option is based on the U.S. Treasury yield curve in effect at the time of the grant. The Company estimates the forfeiture rate based on historical data. This analysis is re-evaluated Certain of the employee stock options granted by the Company are structured to qualify as incentive stock options (“ISOs”). Under current tax regulations, the Company does not receive a tax deduction for the issuance, exercise or disposition of ISOs if the employee meets certain holding requirements. If the employee does not meet the holding requirements, a disqualifying disposition occurs, at which time the Company may receive a tax deduction. The Company does not record tax benefits related to ISOs unless and until a disqualifying disposition is reported. In the event of a disqualifying disposition, the entire tax benefit is recorded as a reduction of income tax expense. The Company has not recognized any income tax benefit for its share-based compensation arrangements due to the fact that the Company does not believe it is more likely than not it will realize the related deferred tax assets.
Income Taxes	Income Taxes The Company uses the asset and liability method to account for income taxes. Deferred tax assets and liabilities are determined based on the expected future tax consequences of temporary differences between the Company’s financial statement carrying amounts and the tax basis of assets and liabilities using enacted tax rates expected to be in effect in the years in which the differences are expected to reverse. The Company currently maintains a 100% valuation allowance on its deferred tax assets.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner
Basic and Diluted Loss Per Common Share	Basic and Diluted Loss Per Common Share Basic net loss per share is computed using the weighted average number of common shares outstanding during the period, excluding restricted stock that has been issued but is not yet vested. Diluted net loss per common share is computed using the weighted average number of common shares outstanding and the weighted average dilutive potential common shares outstanding using the treasury stock method. However, for the nine months ended September 30, 2019 and 2018, diluted net loss per share is the same as basic net loss per share because the inclusion of weighted average shares of unvested restricted common stock, common stock issuable upon the exercise of stock options, and common stock issuable upon the conversion of preferred stock would be anti-dilutive. The following table summarizes outstanding securities not included in the computation of diluted net loss per common share, as their inclusion would be anti-dilutive: Three and Nine Months Ended September 30, 2019 2018 Common Stock Options 1,461,237 1,123,582 Unvested Restricted Common Stock — 52,063 Preferred Stock 1,969,797 1,969,797
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, right-of-use ASU 2016-02 2016-02 8

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2019
Summary of Significant Accounting Policies
Summary of the outstanding securities not included in the computation of diluted net loss per common share as their inclusion would be anti-dilutive	The following table summarizes outstanding securities not included in the computation of diluted net loss per common share, as their inclusion would be anti-dilutive: Three and Nine Months Ended September 30, 2019 2018 Common Stock Options 1,461,237 1,123,582 Unvested Restricted Common Stock — 52,063 Preferred Stock 1,969,797 1,969,797

Cash, Cash Equivalents and Ma_2

Cash, Cash Equivalents and Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2019
Cash, Cash Equivalents and Marketable Securities
Summary of cash, cash equivalents and available-for-sale marketable securities	A summary of cash, cash equivalents and available-for-sale September 30, 2019 Cost Unrealized Unrealized Fair value Cash and cash equivalents: Cash (Level 1) $ 1,975 $ — $ — $ 1,975 Money market funds (Level 1) 87,511 — — 87,511 Corporate debt securities due within 3 months of date of purchase (Level 2) — — — — Total cash and cash equivalents 89,486 — — 89,486 Marketable securities: Corporate debt securities due within 1 year of date of purchase (Level 2) 278,707 264 (9 ) 278,962 Corporate debt securities due within 1 to 2 years of date of purchase (Level 2) 85,125 59 (22 ) 85,162 Total cash, cash equivalents and marketable securities $ 453,318 $ 323 $ (31 ) $ 453,610 December 31, 2018 Cost Unrealized Unrealized Fair value Cash and cash equivalents: Cash (Level 1) $ 2,004 $ — $ — $ 2,004 Money market funds (Level 1) 43,401 — — 43,401 Corporate debt securities due within 3 months of date of purchase (Level 2) 11,974 — — 11,974 Total cash and cash equivalents 57,379 — — 57,379 Marketable securities: Corporate debt securities due within 1 year of date of purchase (Level 2) 426,658 14 (333 ) 426,339 Total cash, cash equivalents and marketable securities $ 484,037 $ 14 $ (333 ) $ 483,718

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	9 Months Ended
	Sep. 30, 2019
Accrued Liabilities, Current [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities as of September 30, 2019 and December 31, 2018 consisted of the following (in thousands): September 30, December 31, Accrued contract research costs $ 7,882 $ 571 Compensation and benefits 1,936 1,797 Other 4,563 3,589 $ 14,381 $ 5,957

Stock-based Compensation (Table

Stock-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2019
Stock-based Compensation
Summary of stock option activity	The following table summarizes stock option activity during the nine months ended September 30, 2019: Shares Weighted Outstanding at January 1, 2019 1,132,618 $ 48.52 Options granted 369,500 119.29 Options exercised (20,131 ) 11.67 Options cancelled (20,750 ) 173.79 Outstanding at September 30, 2019 1,461,237 $ 65.15 Exercisable at September 30, 2019 922,149 $ 40.55
Summary of unvested restricted share activity	The following table summarizes unvested restricted share activity during the nine months ended September 30, 2019: Shares Weighted Outstanding at January 1, 2019 52,063 $ 9.45 Vested (52,063 ) 9.45 Outstanding at September 30, 2019 — $ —
Schedule of stock-based compensation expense	Stock-based compensation expense during the three and nine months ended September 30, 2019 and 2018 was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Stock-based compensation expense by type of award: Stock options $ 4,922 $ 4,852 $ 18,455 $ 8,002 Restricted stock 28 124 272 368 Total stock-based compensation expense $ 4,950 $ 4,976 $ 18,727 $ 8,370 Effect of stock-based compensation expense by line item: Research and development $ 2,404 $ 1,179 $ 6,647 $ 2,287 General and administrative 2,546 3,797 12,080 6,083 Total stock-based compensation expense included in net loss $ 4,950 $ 4,976 $ 18,727 $ 8,370
Schedule of unrecognized stock-based compensation expense	Unrecognized stock-based compensation expense as of September 30, 2019 was as follows (in thousands): Unrecognized Weighted Stock options $ 35,429 2.86 Restricted stock — — Total $ 35,429 2.86

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases
Schedule of future minimum payments for operating leases	Future minimum payments under the Company’s operating leases related to the ROU asset and lease liability as of September 30, 2019 was as follows (in thousand): Operating Leases 2019 $ 89 2020 363 2021 371 2022 31 Thereafter — Total minimum payments $ 854 Less: imputed interest 103 Present value of lease liabilities $ 751

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Income Taxes (Details)	9 Months Ended
	Sep. 30, 2019
Income Taxes
Valuation allowance on deferred tax assets (as a percent)	100.00%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Basic and Diluted Loss Per Common Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stock options
Anti-dilutive securities
Outstanding securities not included in the computation of diluted net loss per common share as their inclusion would be anti-dilutive (in shares)	1,461,237	1,123,582	1,461,237	1,123,582
Unvested Restricted Common Stock
Anti-dilutive securities
Outstanding securities not included in the computation of diluted net loss per common share as their inclusion would be anti-dilutive (in shares)		52,063		52,063
Preferred Stock
Anti-dilutive securities
Outstanding securities not included in the computation of diluted net loss per common share as their inclusion would be anti-dilutive (in shares)	1,969,797	1,969,797	1,969,797	1,969,797

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details)	9 Months Ended
	Sep. 30, 2019
Recent Accounting Pronouncements
Lease, Practical Expedients, Package [true false]	true

Liquidity and Uncertainties (De

Liquidity and Uncertainties (Details) - USD ($) $ 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	Dec. 31, 2018
Liquidity and Uncertainties
Net loss	$ 21,429	$ 19,699	$ 15,080	$ 8,512	$ 6,460	$ 6,364	$ 56,208	$ 21,336
Accumulated deficit	$ 195,480						$ 195,480		$ 139,272

Cash, Cash Equivalents and Ma_3

Cash, Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Cash, Cash Equivalents and Marketable Securities
Total cash, cash equivalents and marketable securities, Unrealized gains	$ 323	$ 14
Total cash, cash equivalents and marketable securities, Unrealized losses	(31)	(333)
Carrying value
Cash, Cash Equivalents and Marketable Securities
Cash and cash equivalents	89,486	57,379
Total cash, cash equivalents and marketable securities, Cost	453,318	484,037
Fair value
Cash, Cash Equivalents and Marketable Securities
Cash and cash equivalents	89,486	57,379
Total cash, cash equivalents and marketable securities, Fair value	$ 453,610	$ 483,718
Corporate debt securities due within 3 months of date of purchase
Cash, Cash Equivalents and Marketable Securities
Maturity period from date of purchase to classify an investment as marketable securities	3 months	3 months
Corporate debt securities due within 3 months of date of purchase | Carrying value | Level 2
Cash, Cash Equivalents and Marketable Securities
Marketable securities, cost	$ 85,125	$ 11,974
Corporate debt securities due within 3 months of date of purchase | Fair value | Level 2
Cash, Cash Equivalents and Marketable Securities
Marketable securities, fair value		$ 11,974
Corporate debt securities due within 1 year of date of purchase
Cash, Cash Equivalents and Marketable Securities
Maturity period from date of purchase to classify an investment as marketable securities	1 year	1 year
Corporate debt securities due within 1 year of date of purchase | Level 2
Cash, Cash Equivalents and Marketable Securities
Marketable securities, unrealized gains	$ 264	$ 14
Marketable securities, unrealized losses	(9)	(333)
Corporate debt securities due within 1 year of date of purchase | Carrying value | Level 2
Cash, Cash Equivalents and Marketable Securities
Marketable securities, cost	278,707	426,658
Corporate debt securities due within 1 year of date of purchase | Fair value | Level 2
Cash, Cash Equivalents and Marketable Securities
Marketable securities, fair value	$ 278,962	426,339
Corporate debt securities due within 1 to 2 years of date of purchase | Maximum [Member]
Cash, Cash Equivalents and Marketable Securities
Maturity period from date of purchase to classify an investment as marketable securities	2 years
Corporate debt securities due within 1 to 2 years of date of purchase | Minimum [Member]
Cash, Cash Equivalents and Marketable Securities
Maturity period from date of purchase to classify an investment as marketable securities	1 year
Corporate debt securities due within 1 to 2 years of date of purchase | Level 2
Cash, Cash Equivalents and Marketable Securities
Marketable securities, unrealized gains	$ 59
Marketable securities, unrealized losses	(22)
Corporate debt securities due within 1 to 2 years of date of purchase | Fair value | Level 2
Cash, Cash Equivalents and Marketable Securities
Marketable securities, fair value	85,162
Cash | Carrying value | Level 1
Cash, Cash Equivalents and Marketable Securities
Cash and cash equivalents	1,975	2,004
Cash | Fair value | Level 1
Cash, Cash Equivalents and Marketable Securities
Cash and cash equivalents	1,975	2,004
Money market funds | Carrying value | Level 1
Cash, Cash Equivalents and Marketable Securities
Cash and cash equivalents	87,511	43,401
Money market funds | Fair value | Level 1
Cash, Cash Equivalents and Marketable Securities
Cash and cash equivalents	$ 87,511	$ 43,401

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accrued Liabilities, Current [Abstract]
Accrued contract research costs	$ 7,882	$ 571
Compensation and benefits	1,936	1,797
Other	4,563	3,589
Total	$ 14,381	$ 5,957

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock (Details)	9 Months Ended
	Sep. 30, 2019Vote
Stockholders' Equity
Number of votes per share that common stockholders are entitled to receive	1

Stockholders' Equity - Preferre

Stockholders' Equity - Preferred Stock (Details)	1 Months Ended
	Jun. 30, 2017Vote$ / sharesshares	Sep. 30, 2019$ / shares	Dec. 31, 2018$ / shares
Stockholders' Equity (Deficit)
Preferred stock, par value (in dollars per share)		$ 0.0001	$ 0.0001
Series A Convertible Preferred Stock
Stockholders' Equity (Deficit)
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock conversion ratio | shares	1
Preferred shares number voting rights | Vote	0

Stockholders' Equity - June 201

Stockholders' Equity - June 2018 Registered Offering of Common Stock (Details) - Common stock - Goldman Sachs & Co. LLC - Underwriting Agreement $ / shares in Units, $ in Millions	1 Months Ended
	Jun. 30, 2018USD ($)$ / sharesshares
Registered Offering
Stockholders' Equity (Deficit)
Number of shares sold by the entity	1,079,580
Issue price of stock | $ / shares	$ 305
Net proceeds after deducting commissions and other transactions costs | $	$ 311.8
Additional Shares
Stockholders' Equity (Deficit)
Number of shares sold by the entity	95,973

Stock-based Compensation - Stoc

Stock-based Compensation - Stock Option (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019
Shares
Outstanding at the end of the year (in shares)	1,461,237
Additional disclosures
Outstanding at the end of the year (in shares)	1,461,237		1,461,237
Stock options
Stock-based compensation expense
Shares available for future issuance			1,352,095
Shares
Outstanding at the beginning of the year (in shares)	1,132,618
Options granted (in shares)	369,500
Options exercised (in shares)	(20,131)
Options cancelled (in shares)	(20,750)
Outstanding at the end of the year (in shares)	1,461,237
Exercisable at the end of the year (in shares)			922,149
Weighted average exercise price
Outstanding at the beginning of the year (in dollars per share)	$ 48.52
Options granted (in dollars per share)	119.29
Options exercised (in dollars per share)	11.67
Options cancelled (in dollars per share)	173.79
Outstanding at the end of the year (in dollars per share)	$ 65.15
Exercisable at the end of the year (in dollars per share)			$ 40.55
Additional disclosures
Proceeds resulting from exercise of stock options	$ 0.2	$ 1.9
Weighted-average grant date fair value of options (in dollars per share)	$ 91.65	$ 136.43
Outstanding at the end of the year (in shares)	1,132,618		1,461,237

Stock-based Compensation - Rest

Stock-based Compensation - Restricted Common Stock (Details) - Unvested Restricted Common Stock	9 Months Ended
	Sep. 30, 2019$ / sharesshares
Shares
Outstanding at January 1, 2019 | shares | shares	52,063
Vested (in shares) | shares | shares	(52,063)
Outstanding at September 30, 2019 | shares | shares	0
Weighted average grant date fair value
Outstanding at January 1, 2019 (in dollars per share) | $ / shares | $ / shares	$ 9.45
Vested (in dollars per share) | $ / shares | $ / shares	9.45
Outstanding at September 30, 2019 (in dollars per share) | $ / shares | $ / shares	$ 0

Stock-based Compensation - Expe

Stock-based Compensation - Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stock-based compensation expense
Stock-based compensation expense	$ 4,950	$ 4,976	$ 18,727	$ 8,370
Research and development
Stock-based compensation expense
Stock-based compensation expense	2,404	1,179	6,647	2,287
General and administrative
Stock-based compensation expense
Stock-based compensation expense	2,546	3,797	12,080	6,083
Stock options
Stock-based compensation expense
Stock-based compensation expense	4,922	4,852	18,455	8,002
Unvested Restricted Common Stock
Stock-based compensation expense
Stock-based compensation expense	$ 28	$ 124	$ 272	$ 368

Stock-based Compensation - Unre

Stock-based Compensation - Unrecognized Expense (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Unrecognized stock-based compensation expense
Unrecognized stock compensation expense	$ 35,429
Weighted average remaining period (in years)	2 years 10 months 9 days
Stock options
Unrecognized stock-based compensation expense
Unrecognized stock compensation expense	$ 35,429
Weighted average remaining period (in years)	2 years 10 months 9 days

Leases (Details)

Leases (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)
Future minimum payments
2019	$ 89	$ 89
2020	363	363
2021	371	371
2022	31	31
Total minimum payments	854	854
Less: imputed interest	103	103
Present value of lease liabilities	$ 751	$ 751
Weighted average, operating lease term	2 years 3 months 18 days	2 years 3 months 18 days
Weighted average, operating discount rate	5.50%	5.50%
Operating lease costs	$ 93	$ 267
Short-term lease costs	23	138
Variable lease costs	$ 0	$ 0

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Commitments and Contingencies
Licensed product sales	$ 0	$ 0
Research, Development and Commercialization Agreement | Hoffmann-La Roche ("Roche")
Commitments and Contingencies
Remainder of future milestone payments	8,000,000
Milestone payment	$ 2,000,000