Editas Medicine (EDIT) 10-Q 5 Aug 21 2021 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2021	Jul. 30, 2021
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2021
Entity File Number	001-37687
Entity Registrant Name	EDITAS MEDICINE, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-4097528
Entity Address, Address Line One	11 Hurley Street
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02141
City Area Code	617
Local Phone Number	401-9000
Title of 12(b) Security	Common Stock
Trading Symbol	EDIT
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		68,261,255
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001650664
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 337,834	$ 139,682
Marketable securities	272,719	262,428
Accounts receivable	331	6,048
Prepaid expenses and other current assets	5,408	10,929
Total current assets	616,292	419,087
Marketable securities	87,584	109,664
Property and equipment, net	14,910	14,020
Right-of-use assets	30,314	25,128
Restricted cash and other non-current assets	6,780	4,703
Total assets	755,880	572,602
Current liabilities:
Accounts payable	4,415	6,408
Accrued expenses	18,627	24,046
Deferred revenue, current	34,000	20,943
Operating lease liabilities	8,974	6,811
Total current liabilities	66,016	58,208
Operating lease liabilities, net of current portion	21,282	19,324
Deferred revenue, net of current portion	55,221	73,984
Other non-current liabilities		27,500
Total liabilities	142,519	179,016
Stockholders' equity
Preferred stock, $0.0001 par value per share: 5,000,000 shares authorized; no shares issued or outstanding
Common stock, $0.0001 par value per share: 195,000,000 shares authorized; 68,249,786 and 62,689,457 shares issued, and 68,159,786 and 62,563,457 shares outstanding at June 30, 2021 and December 31, 2020, respectively	7	6
Additional paid-in capital	1,390,606	1,058,823
Accumulated other comprehensive loss	(71)	(46)
Accumulated deficit	(777,181)	(665,197)
Total stockholders' equity	613,361	393,586
Total liabilities and stockholders' equity	$ 755,880	$ 572,602

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
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	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	195,000,000	195,000,000
Common stock, shares issued	68,249,786	62,689,457
Common stock, shares outstanding	68,159,786	62,563,457

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Condensed Consolidated Statements of Operations
Collaboration and other research and development revenues	$ 379	$ 10,749	$ 6,878	$ 16,472
Revenue type	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember
Operating expenses:
Research and development	$ 33,753	$ 28,007	$ 75,690	$ 62,576
General and administrative	22,027	14,081	43,471	31,852
Total operating expenses	55,780	42,088	119,161	94,428
Operating loss	(55,401)	(31,339)	(112,283)	(77,956)
Other income, net:
Other (expense) income, net	(1)	7,175	19	14,509
Interest income, net	146	592	280	2,151
Total other income, net	145	7,767	299	16,660
Net loss	$ (55,256)	$ (23,572)	$ (111,984)	$ (61,296)
Net loss per share, basic and diluted	$ (0.81)	$ (0.43)	$ (1.67)	$ (1.12)
Weighted-average common shares outstanding, basic (in shares)	67,877,126	55,346,052	66,939,967	54,968,123

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Condensed Consolidated Statements of Comprehensive Loss
Net loss	$ (55,256)	$ (23,572)	$ (111,984)	$ (61,296)
Other comprehensive (loss) income:
Unrealized gain (loss) on marketable debt securities	2	(511)	(25)	76
Comprehensive loss	$ (55,254)	$ (24,083)	$ (112,009)	$ (61,220)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive (Loss) Income	Total
Balance, beginning of period at Dec. 31, 2019	$ 5	$ 811,546	$ (549,221)	$ 107	$ 262,437
Balance, beginning of period (in shares) at Dec. 31, 2019	54,355,798
Statement of Stockholders' Equity (Deficit)
Exercise of stock options		3,047			3,047
Exercise of stock options (in shares)	233,208
Stock-based compensation expense		6,220			6,220
Vesting of restricted common stock awards (in shares)	213,393
Unrealized gain (loss) on marketable debt securities				587	587
Net loss			(37,724)		(37,724)
Balance, end of period at Mar. 31, 2020	$ 5	820,813	(586,945)	694	234,567
Balance, end of period (in shares) at Mar. 31, 2020	54,802,399
Balance, beginning of period at Dec. 31, 2019	$ 5	811,546	(549,221)	107	262,437
Balance, beginning of period (in shares) at Dec. 31, 2019	54,355,798
Statement of Stockholders' Equity (Deficit)
Net loss					(61,296)
Balance, end of period at Jun. 30, 2020	$ 6	1,037,100	(610,517)	183	426,772
Balance, end of period (in shares) at Jun. 30, 2020	62,103,649
Balance, beginning of period at Mar. 31, 2020	$ 5	820,813	(586,945)	694	234,567
Balance, beginning of period (in shares) at Mar. 31, 2020	54,802,399
Statement of Stockholders' Equity (Deficit)
Issuance of common stock for public offering	$ 1	203,681			203,682
Issuance of common stock for public offering (in shares)	6,900,000
Exercise of stock options		6,839			6,839
Exercise of stock options (in shares)	355,812
Stock-based compensation expense		5,417			5,417
Vesting of restricted common stock awards (in shares)	30,194
Purchase of common stock under benefit plans		350			350
Purchase of common stock under benefit plans (in shares)	15,244
Unrealized gain (loss) on marketable debt securities				(511)	(511)
Net loss			(23,572)		(23,572)
Balance, end of period at Jun. 30, 2020	$ 6	1,037,100	(610,517)	183	426,772
Balance, end of period (in shares) at Jun. 30, 2020	62,103,649
Balance, beginning of period at Dec. 31, 2020	$ 6	1,058,823	(665,197)	(46)	393,586
Balance, beginning of period (in shares) at Dec. 31, 2020	62,563,457
Statement of Stockholders' Equity (Deficit)
Issuance of common stock for public offering	$ 1	249,458			249,459
Issuance of common stock for public offering (in shares)	4,025,000
Issuance of common stock for success payment		27,500			27,500
Issuance of common stock for success payment (in shares)	303,599
Exercise of stock options		12,002			12,002
Exercise of stock options (in shares)	501,162
Stock-based compensation expense		12,204			12,204
Vesting of restricted common stock awards (in shares)	79,397
Unrealized gain (loss) on marketable debt securities				(27)	(27)
Net loss			(56,728)		(56,728)
Balance, end of period at Mar. 31, 2021	$ 7	1,359,987	(721,925)	(73)	637,996
Balance, end of period (in shares) at Mar. 31, 2021	67,472,615
Balance, beginning of period at Dec. 31, 2020	$ 6	1,058,823	(665,197)	(46)	393,586
Balance, beginning of period (in shares) at Dec. 31, 2020	62,563,457
Statement of Stockholders' Equity (Deficit)
Net loss					(111,984)
Balance, end of period at Jun. 30, 2021	$ 7	1,390,606	(777,181)	(71)	613,361
Balance, end of period (in shares) at Jun. 30, 2021	68,159,786
Balance, beginning of period at Mar. 31, 2021	$ 7	1,359,987	(721,925)	(73)	637,996
Balance, beginning of period (in shares) at Mar. 31, 2021	67,472,615
Statement of Stockholders' Equity (Deficit)
Exercise of stock options		16,567			16,567
Exercise of stock options (in shares)	629,973
Stock-based compensation expense		13,526			13,526
Vesting of restricted common stock awards (in shares)	37,790
Purchase of common stock under benefit plans		526			526
Purchase of common stock under benefit plans (in shares)	19,408
Unrealized gain (loss) on marketable debt securities				2	2
Net loss			(55,256)		(55,256)
Balance, end of period at Jun. 30, 2021	$ 7	$ 1,390,606	$ (777,181)	$ (71)	$ 613,361
Balance, end of period (in shares) at Jun. 30, 2021	68,159,786

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Cash flow from operating activities
Net loss	$ (111,984)	$ (61,296)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	25,730	11,637
Depreciation	2,352	1,669
Unrealized gain on corporate equity securities		14,525
Other non-cash items, net	910	(289)
Changes in operating assets and liabilities:
Accounts receivable	5,717	(1,447)
Prepaid expenses and other current assets	5,521	(3,254)
Right-of-use assets	4,567	192
Other non-current assets	(2,077)	93
Accounts payable	(1,818)	1,026
Accrued expenses	(6,016)	(12,439)
Deferred revenue	(5,706)	(7,375)
Operating lease liabilities	(5,632)	(278)
Other current and non-current liabilities		1,344
Net cash used in operating activities	(88,436)	(84,942)
Cash flow from investing activities
Purchases of property and equipment	(2,788)	(3,993)
Proceeds from the sale of equipment		14
Purchases of marketable securities	(194,127)	(66,384)
Proceeds from maturities of marketable securities	204,950	191,000
Net cash provided by investing activities	8,035	120,637
Cash flow from financing activities
Proceeds from offering of common stock, net of issuance costs	249,458	203,964
Proceeds from exercise of stock options	28,569	9,886
Issuance of common stock under benefit plans	526	350
Net cash provided by financing activities	278,553	214,200
Net increase in cash, cash equivalents, and restricted cash	198,152	249,895
Cash, cash equivalents, and restricted cash, beginning of period	143,559	239,802	$ 239,802
Cash, cash equivalents, and restricted cash, end of period	341,711	489,697	$ 143,559
Supplemental disclosure of cash and non-cash activities:
Fixed asset additions included in accounts payable and accrued expenses	1,079	429
Cash paid in connection with operating lease liabilities	6,731	5,125
Offering costs included in accounts payable and accrued expenses		282
Right-of-use assets obtained in exchange of operating lease obligations	$ 9,753	$ 3,319

Nature of Business

Nature of Business	6 Months Ended
	Jun. 30, 2021
Nature of Business
Nature of Business	1. Nature of Business ​ Editas Medicine, Inc. (the “Company”) is a leading, clinical stage genome editing company dedicated to developing potentially transformative genomic medicines to treat a broad range of serious diseases. The Company was incorporated in the state of Delaware in September 2013. Its principal offices are in Cambridge, Massachusetts. Since its inception, the Company has devoted substantially all of its efforts to business planning, research and development, recruiting management and technical staff, and raising capital. The Company has primarily financed its operations through various equity financings, payments received under a research collaboration with Juno Therapeutics, a wholly-owned subsidiary of the Bristol-Myers Squibb Company (“Juno Therapeutics”), and payments received under a strategic alliance and option agreement with Allergan Pharmaceuticals International Limited (together with its affiliates, “Allergan”), which was terminated in August 2020. The Company is subject to risks common to companies in the biotechnology industry, including but not limited to, risks of failure of preclinical studies and clinical trials, the need to obtain marketing approval for any drug product candidate that it may identify and develop, 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. Liquidity ​ In May 2021, the Company entered into a common stock sales agreement with Cowen and Company, LLC (“Cowen”), under which the Company from time to time can issue and sell shares of its common stock through Cowen in at-the-market offerings for aggregate gross sale proceeds of up to $300.0 million (the “ATM Facility”). As of June 30, 2021, the Company has not sold any shares of our common stock under the ATM Facility. ​ In January 2021, the Company completed a public offering whereby it sold 3,500,000 shares of its common stock and received net proceeds of approximately $216.9 million. In February 2021, the underwriters in the public offering exercised their option to purchase an additional 525,000 shares, resulting in additional net proceeds to the Company of approximately $32.6 million. ​ The Company has incurred annual net operating losses in every year since its inception. The Company expects that its existing cash, cash equivalents and marketable securities at June 30, 2021 and anticipated interest income will enable it to fund its operating expenses and capital expenditure requirements well into 2023 . The Company had an accumulated deficit of $777.2 million at June 30, 2021, and will require substantial additional capital to fund its operations. The Company has never generated any product revenue. There can be no assurance that the Company will be able to obtain additional debt or equity financing or generate product revenue or revenues from collaborative partners, on terms acceptable to the Company, on a timely basis or at all. The failure 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.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies ​ Unaudited Interim Financial Information ​ The condensed consolidated financial statements of the Company included herein have been prepared, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these condensed consolidated financial statements should be read in conjunction with the financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2020 (the “Annual Report”). ​ The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiary, Editas Securities Corporation. All intercompany transactions and balances of the subsidiary have been eliminated in consolidation. In the opinion of management, the information furnished reflects all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the results for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The three months ended June 30, 2021 and 2020 are referred to as the second quarter of 2021 and 2020, respectively. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period. ​ Summary of Significant Accounting Policies ​ The Company’s significant accounting policies are described in Note 2, “Summary of significant accounting policies,” to the consolidated financial statements included in the Annual Report. There have been no material changes to the significant accounting policies previously disclosed in the Annual Report. ​ ​

Cash Equivalents and Marketable

Cash Equivalents and Marketable Securities	6 Months Ended
	Jun. 30, 2021
Cash Equivalents and Marketable Securities
Cash Equivalents and Marketable Securities	3. Cash Equivalents and Marketable Securities ​ Cash equivalents and marketable securities consisted of the following at June 30, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ​ ​ Gross ​ Gross ​ ​ ​ ​ Amortized ​ for Credit ​ ​ Unrealized ​ Unrealized ​ Fair June 30, 2021 ​ Cost ​ Losses ​ ​ Gains ​ Losses ​ Value Cash equivalents and marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 337,834 ​ $ — ​ ​ $ — ​ $ — ​ $ 337,834 U.S. Treasuries ​ ​ 55,119 ​ ​ — ​ ​ ​ 3 ​ ​ (10) ​ ​ 55,112 Government agency securities ​ ​ 142,367 ​ ​ — ​ ​ ​ 4 ​ ​ (48) ​ ​ 142,323 Commercial Paper ​ ​ 100,659 ​ ​ — ​ ​ ​ 4 ​ ​ — ​ ​ 100,663 Corporate notes/bonds ​ ​ 62,229 ​ ​ — ​ ​ ​ 2 ​ ​ (26) ​ ​ 62,205 Total ​ $ 698,208 ​ $ — ​ ​ $ 13 ​ $ (84) ​ $ 698,137 ​ Cash equivalents and marketable securities consisted of the following at December 31, 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ​ ​ Gross ​ Gross ​ ​ ​ ​ Amortized ​ for Credit ​ ​ Unrealized ​ Unrealized ​ Fair December 31, 2020 ​ Cost ​ Losses ​ ​ Gains ​ Losses ​ Value Cash equivalents and marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 139,682 ​ $ — ​ ​ $ — ​ $ — ​ $ 139,682 U.S. Treasuries ​ ​ 180,376 ​ ​ — ​ ​ ​ 8 ​ ​ (11) ​ ​ 180,373 Government agency securities ​ ​ 107,665 ​ ​ — ​ ​ ​ — ​ ​ (20) ​ ​ 107,645 Commercial paper ​ ​ 41,912 ​ ​ — ​ ​ ​ — ​ ​ (8) ​ ​ 41,904 Corporate notes/bonds ​ ​ 42,185 ​ ​ — ​ ​ ​ 10 ​ ​ (25) ​ ​ 42,170 Total ​ $ 511,820 ​ $ — ​ ​ $ 18 ​ $ (64) ​ $ 511,774 ​ As of June 30, 2021, the Company did not hold any marketable securities that had been in an unrealized loss position for more than twelve months. Furthermore, the Company has determined that there were no material changes in the credit risk of the debt securities. As of June 30, 2021, the Company holds 30 securities with an aggregate fair value of $87.6 million that had remaining maturities between one and two years. ​ There were no realized gains or losses on available-for-sale securities during the six months ended June 30, 2021 or 2020.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2021
Fair Value Measurements
Fair Value Measurements	4. Fair Value Measurements ​ Assets measured at fair value on a recurring basis as of June 30, 2021 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices Significant ​ ​ ​ ​ ​ ​ ​ in Active ​ Other ​ Significant ​ ​ ​ ​ ​ Markets for ​ Observable ​ Unobservable ​ ​ June 30, ​ Identical Assets ​ Inputs ​ Inputs Financial Assets ​ 2021 ​ (Level 1) ​ (Level 2) ​ (Level 3) Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 337,834 ​ $ 337,834 ​ $ — ​ $ — Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasuries ​ ​ 55,112 ​ ​ 55,112 ​ ​ — ​ ​ — Government agency securities ​ ​ 142,323 ​ ​ — ​ ​ 142,323 ​ ​ — Commercial paper ​ ​ 100,663 ​ ​ — ​ ​ 100,663 ​ ​ — Corporate notes/bonds ​ ​ 62,205 ​ ​ — ​ ​ 62,205 ​ ​ — Restricted cash and other non-current assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ ​ 3,877 ​ ​ 3,877 ​ ​ — ​ ​ — Total financial assets ​ $ 702,014 ​ $ 396,823 ​ $ 305,191 ​ $ — ​ Assets measured at fair value on a recurring basis as of December 31, 2020 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices Significant ​ ​ ​ ​ ​ ​ ​ in Active ​ Other ​ Significant ​ ​ ​ ​ ​ Markets for ​ Observable ​ Unobservable ​ ​ December 31, ​ Identical Assets ​ Inputs ​ Inputs Financial Assets ​ 2020 ​ (Level 1) ​ (Level 2) ​ (Level 3) Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 139,682 ​ $ 139,682 ​ $ — ​ $ — Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasuries ​ ​ 180,373 ​ ​ 180,373 ​ ​ — ​ ​ — Government agency securities ​ ​ 107,645 ​ ​ — ​ ​ 107,645 ​ ​ — Commercial paper ​ ​ 41,904 ​ ​ — ​ ​ 41,904 ​ ​ ​ Corporate notes/bonds ​ ​ 42,170 ​ ​ — ​ ​ 42,170 ​ ​ ​ Restricted cash and other non-current assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ ​ 3,877 ​ ​ 3,877 ​ ​ — ​ ​ — Total financial assets ​ $ 515,651 ​ $ 323,932 ​ $ 191,719 ​ $ — ​

Accrued Expenses

Accrued Expenses	6 Months Ended
	Jun. 30, 2021
Accrued Expenses
Accrued Expenses	5. Accrued Expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of ​ ​ June 30, ​ December 31, ​ 2021 2020 External research and development expenses ​ $ 6,510 ​ $ 12,820 Employee related expenses ​ ​ 5,546 ​ 5,323 Intellectual property and patent related fees ​ ​ 5,116 ​ ​ 4,240 Other expenses ​ ​ 914 ​ ​ 359 Professional service expenses ​ ​ 541 ​ ​ 533 Sublicensing expenses ​ ​ — ​ ​ 771 Total accrued expenses ​ $ 18,627 ​ $ 24,046 ​ ​ ​ ​ ​ ​ ​ ​

Property and Equipment, net

Property and Equipment, net	6 Months Ended
	Jun. 30, 2021
Property and Equipment, net
Property and Equipment, net	6. Property and Equipment, net ​ Property and equipment, net consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of ​ ​ June 30, ​ December 31, ​ 2021 2020 Laboratory equipment ​ $ 19,431 ​ $ 18,433 Leasehold improvements ​ ​ 5,400 ​ ​ 4,967 Construction-in-progress ​ 2,040 ​ 500 Computer equipment ​ ​ 858 ​ ​ 858 Furniture and office equipment ​ ​ 239 ​ ​ 239 Software ​ 118 ​ 118 Total property and equipment ​ 28,086 ​ 25,115 Less: accumulated depreciation ​ (13,176) ​ (11,095) Property and equipment, net ​ $ 14,910 ​ $ 14,020 ​

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies
Commitments and Contingencies	7. Commitments and Contingencies ​ ​ Licensor Expense Reimbursement ​ The Company is obligated to reimburse The Broad Institute, Inc. (“Broad”) and the President and Fellows of Harvard College (“Harvard”) for expenses incurred by each of them associated with the prosecution and maintenance of the patent rights that the Company licenses from them pursuant to the license agreement by and among the Company, Broad and Harvard, including the interference and opposition proceedings involving patents licensed to the Company under the license agreement, and other license agreements between the Company and Broad. As such, the Company anticipates that it has a substantial commitment in connection with these proceedings until such time as these proceedings have been resolved, but the amount of such commitment is not determinable. The Company incurred an aggregate of $3.4 million and $7.2 million in expense during the three and six months ended June 30, 2021, respectively, for such reimbursement. The Company incurred an aggregate of $2.8 million and $6.6 million in expense during the three and six months ended June 30, 2020, respectively, for such reimbursement.

Collaboration and Profit-Sharin

Collaboration and Profit-Sharing Agreements	6 Months Ended
	Jun. 30, 2021
Collaboration and Profit-Sharing Agreements
Collaboration and Profit-Sharing Agreements	8 Collaboration and Profit-Sharing Agreements ​ The Company has entered into multiple collaborations, out-licenses and strategic alliances with third parties that typically involve payments to or from the Company, including up-front payments, payments for research and development services, option payments, milestone payments and royalty payments to or from the Company. The terms and conditions as well as the accounting analysis for the Company’s significant collaborations, out-licenses and strategic alliances are described in Note 9, “Collaboration and Profit-Sharing Agreements” to the consolidated financial statements included in the Annual Report. There have been no material changes to the terms and conditions, or the accounting conclusions previously disclosed in the Annual Report. ​ ​ ​ Collaboration Revenue ​ As of June 30, 2021, the Company’s contract liabilities were primarily related to the Company’s collaboration with Juno Therapeutics. The following table presents changes in the Company’s accounts receivable and contract liabilities for the six months ended June 30, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the six months ended June 30, 2021 Balance at December 31, 2020 ​ Additions ​ Deductions ​ Balance at June 30, 2021 Accounts receivable $ 6,048 ​ $ 360 ​ $ (6,077) ​ $ 331 Contract liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred revenue $ 94,927 ​ $ — ​ $ (5,706) ​ $ 89,221 ​ During the three and six months ended June 30, 2021, the Company recognized the following collaboration revenue (in thousands): ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended Revenue recognized in the period from: June 30, 2021 Amounts included in deferred revenue at the beginning of the period $ — ​ $ 5,706 Performance obligations satisfied in previous periods $ — ​ $ — ​

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2021
Stock-Based Compensation
Stock-Based Compensation	9 Stock-based Compensation ​ Total compensation cost recognized for all stock-based compensation awards in the condensed consolidated statements of operations was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ ​ 2021 ​ 2020 ​ 2021 ​ 2020 Research and development ​ $ 4,171 ​ $ 2,673 ​ $ 8,137 ​ $ 5,730 General and administrative ​ 9,355 ​ 2,744 ​ 17,593 ​ 5,907 Total stock-based compensation expense ​ $ 13,526 ​ $ 5,417 ​ $ 25,730 ​ $ 11,637 ​ Restricted Stock and Restricted Stock Unit Awards ​ The following is a summary of restricted stock and restricted stock unit awards activity for the six months ended June 30, 2021: ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Average ​ ​ ​ ​ Grant Date ​ ​ ​ ​ Fair Value ​ ​ Shares ​ Per Share Unvested restricted stock and restricted stock unit awards as of December 31, 2020 507,450 ​ $ 27.35 Issued 601,767 ​ $ 47.84 Vested (117,187) ​ $ 27.42 Forfeited ​ (131,434) ​ $ 38.40 Unvested restricted stock and restricted stock unit awards as of June 30, 2021 860,596 ​ $ 40.54 ​ ​ As of June 30, 2021, total unrecognized compensation expense related to unvested restricted stock and restricted stock unit awards was $23.3 million, which the Company expects to recognize over a remaining weighted-average period of 2.3 years. ​ Stock Options ​ The following is a summary of stock option activity for the six months ended June 30, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Average Remaining Aggregate Intrinsic ​ ​ Shares ​ Exercise Price ​ Contractual Life (years) ​ Value (in thousands) Outstanding at December 31, 2020 3,912,257 ​ $ 27.26 ​ 7.9 ​ $ 167,640 Granted ​ 1,133,470 ​ $ 44.48 ​ ​ ​ ​ ​ Exercised ​ (1,131,135) ​ $ 25.26 ​ ​ ​ ​ ​ Cancelled ​ (661,719) ​ $ 28.82 ​ ​ ​ ​ ​ Outstanding at June 30, 2021 3,252,873 ​ $ 33.64 ​ 8.1 ​ $ 75,413 Exercisable at June 30, 2021 1,254,471 ​ $ 28.17 ​ 7.2 ​ $ 35,714 ​ The stock options granted in the six months ended June 30, 2021 include option grants to the Company’s Chief Executive Officer to purchase 196,637 and 341,978 shares of the Company’s common stock that contained market-based vesting provisions and performance-based vesting provisions, respectively. The Company recognizes the fair value of the market-based options over the earlier of the derived service period, valued using the Monte-Carlo simulation model, or when the market-based vesting conditions are met. The Company recognizes the fair value of the performance-based options through the expected achievement date if the performance-based vesting provisions are deemed probable. ​ As of June 30, 2021, total unrecognized compensation expense related to stock options was $38.8 million, which the Company expects to recognize over a remaining weighted-average period of 2.6 years.

Net Income (Loss) per Share

Net Income (Loss) per Share	6 Months Ended
	Jun. 30, 2021
Net Income (Loss) per Share
Net Income (Loss) per Share	10. Net Loss per Share ​ Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock and potentially dilutive securities outstanding for the period determined using the treasury stock and if converted methods. Contingently issuable shares are included in the calculation of basic loss per share as of the beginning of the period in which all the necessary conditions have been satisfied. Contingently issuable shares are included in diluted loss per share based on the number of shares, if any, that would be issuable under the terms of the arrangement if the end of the reporting period was the end of the contingency period, if the results are dilutive. ​ For purposes of the diluted net loss per share calculation, stock options are considered to be common stock equivalents, but they were excluded from the Company’s calculation of diluted net loss per share allocable to common stockholders because their inclusion would have been anti-dilutive. Therefore, basic and diluted net loss per share applicable to common stockholders were the same for all periods presented. ​ The following common stock equivalents were excluded from the calculation of diluted net loss per share allocable to common stockholders because their inclusion would have been anti-dilutive: ​ ​ ​ ​ ​ ​ ​ ​ For the three and six months ended ​ ​ ​ June 30, ​ ​ 2021 ​ 2020 ​ Unvested restricted stock and restricted stock unit awards 860,596 ​ 516,131 ​ Outstanding stock options 3,252,873 ​ 3,979,725 ​ Total 4,113,469 ​ 4,495,856 ​ ​

Cash Equivalents and Marketab_2

Cash Equivalents and Marketable Securities (Tables)	6 Months Ended
	Jun. 30, 2021
Cash Equivalents and Marketable Securities
Schedule of cash equivalents and marketable securities	Cash equivalents and marketable securities consisted of the following at June 30, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ​ ​ Gross ​ Gross ​ ​ ​ ​ Amortized ​ for Credit ​ ​ Unrealized ​ Unrealized ​ Fair June 30, 2021 ​ Cost ​ Losses ​ ​ Gains ​ Losses ​ Value Cash equivalents and marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 337,834 ​ $ — ​ ​ $ — ​ $ — ​ $ 337,834 U.S. Treasuries ​ ​ 55,119 ​ ​ — ​ ​ ​ 3 ​ ​ (10) ​ ​ 55,112 Government agency securities ​ ​ 142,367 ​ ​ — ​ ​ ​ 4 ​ ​ (48) ​ ​ 142,323 Commercial Paper ​ ​ 100,659 ​ ​ — ​ ​ ​ 4 ​ ​ — ​ ​ 100,663 Corporate notes/bonds ​ ​ 62,229 ​ ​ — ​ ​ ​ 2 ​ ​ (26) ​ ​ 62,205 Total ​ $ 698,208 ​ $ — ​ ​ $ 13 ​ $ (84) ​ $ 698,137 ​ Cash equivalents and marketable securities consisted of the following at December 31, 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ​ ​ Gross ​ Gross ​ ​ ​ ​ Amortized ​ for Credit ​ ​ Unrealized ​ Unrealized ​ Fair December 31, 2020 ​ Cost ​ Losses ​ ​ Gains ​ Losses ​ Value Cash equivalents and marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 139,682 ​ $ — ​ ​ $ — ​ $ — ​ $ 139,682 U.S. Treasuries ​ ​ 180,376 ​ ​ — ​ ​ ​ 8 ​ ​ (11) ​ ​ 180,373 Government agency securities ​ ​ 107,665 ​ ​ — ​ ​ ​ — ​ ​ (20) ​ ​ 107,645 Commercial paper ​ ​ 41,912 ​ ​ — ​ ​ ​ — ​ ​ (8) ​ ​ 41,904 Corporate notes/bonds ​ ​ 42,185 ​ ​ — ​ ​ ​ 10 ​ ​ (25) ​ ​ 42,170 Total ​ $ 511,820 ​ $ — ​ ​ $ 18 ​ $ (64) ​ $ 511,774

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Measurements
Schedule of assets measured at fair value on a recurring basis	Assets measured at fair value on a recurring basis as of June 30, 2021 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices Significant ​ ​ ​ ​ ​ ​ ​ in Active ​ Other ​ Significant ​ ​ ​ ​ ​ Markets for ​ Observable ​ Unobservable ​ ​ June 30, ​ Identical Assets ​ Inputs ​ Inputs Financial Assets ​ 2021 ​ (Level 1) ​ (Level 2) ​ (Level 3) Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 337,834 ​ $ 337,834 ​ $ — ​ $ — Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasuries ​ ​ 55,112 ​ ​ 55,112 ​ ​ — ​ ​ — Government agency securities ​ ​ 142,323 ​ ​ — ​ ​ 142,323 ​ ​ — Commercial paper ​ ​ 100,663 ​ ​ — ​ ​ 100,663 ​ ​ — Corporate notes/bonds ​ ​ 62,205 ​ ​ — ​ ​ 62,205 ​ ​ — Restricted cash and other non-current assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ ​ 3,877 ​ ​ 3,877 ​ ​ — ​ ​ — Total financial assets ​ $ 702,014 ​ $ 396,823 ​ $ 305,191 ​ $ — ​ Assets measured at fair value on a recurring basis as of December 31, 2020 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices Significant ​ ​ ​ ​ ​ ​ ​ in Active ​ Other ​ Significant ​ ​ ​ ​ ​ Markets for ​ Observable ​ Unobservable ​ ​ December 31, ​ Identical Assets ​ Inputs ​ Inputs Financial Assets ​ 2020 ​ (Level 1) ​ (Level 2) ​ (Level 3) Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 139,682 ​ $ 139,682 ​ $ — ​ $ — Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasuries ​ ​ 180,373 ​ ​ 180,373 ​ ​ — ​ ​ — Government agency securities ​ ​ 107,645 ​ ​ — ​ ​ 107,645 ​ ​ — Commercial paper ​ ​ 41,904 ​ ​ — ​ ​ 41,904 ​ ​ ​ Corporate notes/bonds ​ ​ 42,170 ​ ​ — ​ ​ 42,170 ​ ​ ​ Restricted cash and other non-current assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ ​ 3,877 ​ ​ 3,877 ​ ​ — ​ ​ — Total financial assets ​ $ 515,651 ​ $ 323,932 ​ $ 191,719 ​ $ —

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Jun. 30, 2021
Accrued Expenses
Schedule of accrued expenses	​ ​ ​ ​ ​ ​ ​ ​ ​ As of ​ ​ June 30, ​ December 31, ​ 2021 2020 External research and development expenses ​ $ 6,510 ​ $ 12,820 Employee related expenses ​ ​ 5,546 ​ 5,323 Intellectual property and patent related fees ​ ​ 5,116 ​ ​ 4,240 Other expenses ​ ​ 914 ​ ​ 359 Professional service expenses ​ ​ 541 ​ ​ 533 Sublicensing expenses ​ ​ — ​ ​ 771 Total accrued expenses ​ $ 18,627 ​ $ 24,046 ​ ​ ​ ​ ​ ​ ​

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	6 Months Ended
	Jun. 30, 2021
Property and Equipment, net
Schedule of property and equipment, net	Property and equipment, net consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of ​ ​ June 30, ​ December 31, ​ 2021 2020 Laboratory equipment ​ $ 19,431 ​ $ 18,433 Leasehold improvements ​ ​ 5,400 ​ ​ 4,967 Construction-in-progress ​ 2,040 ​ 500 Computer equipment ​ ​ 858 ​ ​ 858 Furniture and office equipment ​ ​ 239 ​ ​ 239 Software ​ 118 ​ 118 Total property and equipment ​ 28,086 ​ 25,115 Less: accumulated depreciation ​ (13,176) ​ (11,095) Property and equipment, net ​ $ 14,910 ​ $ 14,020

Collaboration and Profit-Shar_2

Collaboration and Profit-Sharing Agreements (Tables)	6 Months Ended
	Jun. 30, 2021
Collaboration and Profit-Sharing Agreements
Schedule of accounts receivable and contract liabilities	The following table presents changes in the Company’s accounts receivable and contract liabilities for the six months ended June 30, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the six months ended June 30, 2021 Balance at December 31, 2020 ​ Additions ​ Deductions ​ Balance at June 30, 2021 Accounts receivable $ 6,048 ​ $ 360 ​ $ (6,077) ​ $ 331 Contract liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred revenue $ 94,927 ​ $ — ​ $ (5,706) ​ $ 89,221
Schedule of change in contract assets and contract liabilities	During the three and six months ended June 30, 2021, the Company recognized the following collaboration revenue (in thousands): ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended Revenue recognized in the period from: June 30, 2021 Amounts included in deferred revenue at the beginning of the period $ — ​ $ 5,706 Performance obligations satisfied in previous periods $ — ​ $ —

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2021
Stock-Based Compensation
Schedule of stock-based compensation expense	Total compensation cost recognized for all stock-based compensation awards in the condensed consolidated statements of operations was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ ​ 2021 ​ 2020 ​ 2021 ​ 2020 Research and development ​ $ 4,171 ​ $ 2,673 ​ $ 8,137 ​ $ 5,730 General and administrative ​ 9,355 ​ 2,744 ​ 17,593 ​ 5,907 Total stock-based compensation expense ​ $ 13,526 ​ $ 5,417 ​ $ 25,730 ​ $ 11,637
Schedule of changes in unvested restricted stock	The following is a summary of restricted stock and restricted stock unit awards activity for the six months ended June 30, 2021: ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Average ​ ​ ​ ​ Grant Date ​ ​ ​ ​ Fair Value ​ ​ Shares ​ Per Share Unvested restricted stock and restricted stock unit awards as of December 31, 2020 507,450 ​ $ 27.35 Issued 601,767 ​ $ 47.84 Vested (117,187) ​ $ 27.42 Forfeited ​ (131,434) ​ $ 38.40 Unvested restricted stock and restricted stock unit awards as of June 30, 2021 860,596 ​ $ 40.54
Schedule of stock option activity	The following is a summary of stock option activity for the six months ended June 30, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Average Remaining Aggregate Intrinsic ​ ​ Shares ​ Exercise Price ​ Contractual Life (years) ​ Value (in thousands) Outstanding at December 31, 2020 3,912,257 ​ $ 27.26 ​ 7.9 ​ $ 167,640 Granted ​ 1,133,470 ​ $ 44.48 ​ ​ ​ ​ ​ Exercised ​ (1,131,135) ​ $ 25.26 ​ ​ ​ ​ ​ Cancelled ​ (661,719) ​ $ 28.82 ​ ​ ​ ​ ​ Outstanding at June 30, 2021 3,252,873 ​ $ 33.64 ​ 8.1 ​ $ 75,413 Exercisable at June 30, 2021 1,254,471 ​ $ 28.17 ​ 7.2 ​ $ 35,714

Net Income (Loss) per Share (Ta

Net Income (Loss) per Share (Tables)	6 Months Ended
	Jun. 30, 2021
Net Income (Loss) per Share
Schedule of anti-dilutive common stock equivalents	The following common stock equivalents were excluded from the calculation of diluted net loss per share allocable to common stockholders because their inclusion would have been anti-dilutive: ​ ​ ​ ​ ​ ​ ​ ​ For the three and six months ended ​ ​ ​ June 30, ​ ​ 2021 ​ 2020 ​ Unvested restricted stock and restricted stock unit awards 860,596 ​ 516,131 ​ Outstanding stock options 3,252,873 ​ 3,979,725 ​ Total 4,113,469 ​ 4,495,856 ​

Nature of Business (Details)

Nature of Business (Details) - USD ($) $ in Thousands	1 Months Ended		2 Months Ended	6 Months Ended
	Feb. 28, 2021	Jan. 31, 2021	Jun. 30, 2021	Jun. 30, 2021	Jun. 30, 2020	May 31, 2021	Dec. 31, 2020
Liquidity
Proceeds from offering of common stock, net of issuance costs				$ 249,458	$ 203,964
Accumulated deficit			$ 777,181	$ 777,181			$ 665,197
At Market Offering
Liquidity
Number of common stock issued			0
Sales agreement amount of aggregate sale proceeds of common stock agreed to be issued						$ 300,000
Public Offering
Liquidity
Number of common stock issued		3,500,000
Aggregate net proceeds		$ 216,900
Overallotment Option
Liquidity
Number of common stock issued	525,000
Aggregate net proceeds	$ 32,600

Cash Equivalents and Marketab_3

Cash Equivalents and Marketable Securities (Details) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2021USD ($)securityitem	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Cash Equivalents and Marketable Securities
Amortized Cost	$ 698,208		$ 511,820
Gross Unrealized Gains	13		18
Gross Unrealized Losses	(84)		(64)
Fair Value	$ 698,137		511,774
Equity securities included in other non-current assets:
Gross Unrealized Gains		$ 14,525
Number of securities in an unrealized loss position for more than 12 months | item	0
Number of noncurrent securities | security	30
Noncurrent marketable securities	$ 87,584		109,664
Realized gains (losses) on available-for-sale securities	0	$ 0
U.S. Treasuries
Cash Equivalents and Marketable Securities
Amortized Cost	55,119		180,376
Gross Unrealized Gains	3		8
Gross Unrealized Losses	(10)		(11)
Fair Value	55,112		180,373
Government agency securities
Cash Equivalents and Marketable Securities
Amortized Cost	142,367		107,665
Gross Unrealized Gains	4
Gross Unrealized Losses	(48)		(20)
Fair Value	142,323		107,645
Commercial paper
Cash Equivalents and Marketable Securities
Amortized Cost	100,659		41,912
Gross Unrealized Gains	4
Gross Unrealized Losses			(8)
Fair Value	100,663		41,904
Corporate notes/bonds
Cash Equivalents and Marketable Securities
Amortized Cost	62,229
Gross Unrealized Gains	2
Gross Unrealized Losses	(26)
Fair Value	62,205
Equity securities included in other non-current assets:
Amortized Cost			42,185
Gross Unrealized Gains			10
Gross Unrealized Losses			(25)
Fair Value			42,170
Money market funds
Cash Equivalents and Marketable Securities
Amortized Cost	337,834		139,682
Fair Value	$ 337,834		$ 139,682

Fair Value Measurements - Recur

Fair Value Measurements - Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financial Assets
Marketable securities	$ 698,137	$ 511,774
U.S. Treasuries
Financial Assets
Marketable securities	55,112	180,373
Commercial paper
Financial Assets
Marketable securities	100,663	41,904
Corporate notes/bonds
Financial Assets
Equity securities		42,185
Marketable securities	62,205
Money market funds
Financial Assets
Marketable securities	337,834	139,682
Recurring
Financial Assets
Total financial assets	702,014	515,651
Recurring | U.S. Treasuries
Financial Assets
Marketable securities	55,112	180,373
Recurring | Government agency securities
Financial Assets
Marketable securities	142,323	107,645
Recurring | Commercial paper
Financial Assets
Marketable securities	100,663	41,904
Recurring | Corporate notes/bonds
Financial Assets
Marketable securities	62,205	42,170
Recurring | Money market funds
Financial Assets
Cash and cash equivalents	337,834	139,682
Recurring | Level 1
Financial Assets
Total financial assets	396,823	323,932
Recurring | Level 1 | U.S. Treasuries
Financial Assets
Marketable securities	55,112	180,373
Recurring | Level 1 | Money market funds
Financial Assets
Cash and cash equivalents	337,834	139,682
Recurring | Level 2
Financial Assets
Total financial assets	305,191	191,719
Recurring | Level 2 | Government agency securities
Financial Assets
Marketable securities	142,323	107,645
Recurring | Level 2 | Commercial paper
Financial Assets
Marketable securities	100,663	41,904
Recurring | Level 2 | Corporate notes/bonds
Financial Assets
Marketable securities	$ 62,205	$ 42,170

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Accrued Expenses
External research and development expenses	$ 6,510	$ 12,820
Employee related expenses	5,546	5,323
Intellectual property and patent related fees	5,116	4,240
Other expenses	914	359
Professional service expenses	541	533
Sublicensing expenses		771
Total accrued expenses	$ 18,627	$ 24,046

Property and Equipment, net (De

Property and Equipment, net (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Property and equipment disclosures
Total property and equipment	$ 28,086	$ 25,115
Less: accumulated depreciation	(13,176)	(11,095)
Property and equipment, net	14,910	14,020
Laboratory equipment
Property and equipment disclosures
Total property and equipment	19,431	18,433
Leasehold improvements
Property and equipment disclosures
Total property and equipment	5,400	4,967
Construction-in-progress
Property and equipment disclosures
Total property and equipment	2,040	500
Computer equipment
Property and equipment disclosures
Total property and equipment	858	858
Furniture and office equipment
Property and equipment disclosures
Total property and equipment	239	239
Software
Property and equipment disclosures
Total property and equipment	$ 118	$ 118

Commitments and Contingencies -

Commitments and Contingencies - Licensor Expense Reimbursement (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Licensor Expense Reimbursement
Commitments and contingencies
Expense for prosecution and maintenance of patent rights	$ 3.4	$ 2.8	$ 7.2	$ 6.6

Collaboration and Profit-Shar_3

Collaboration and Profit-Sharing Agreements - Allegran pharmaceuticals strategic alliance and profit sharing agreement (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Collaboration and Profit-Sharing Agreements
Revenue recognized			$ 5,706
Collaboration and other research and development revenues	$ 379	$ 10,749	6,878	$ 16,472
Deferred revenue	$ 89,221		$ 89,221		$ 94,927

Collaboration and Profit-Shar_4

Collaboration and Profit-Sharing Agreements - Revenue Recognition (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Accounts receivable
Accounts receivable, Balance at Beginning of Period	$ 6,048
Accounts Receivable, Additions	360
Accounts Receivable, Deductions	(6,077)
Accounts receivable, Balance at End of Period	331
Contract liabilities:
Deferred Revenue, Balance at Beginning of Period	94,927
Deferred revenue, Deductions	(5,706)
Deferred Revenue, Balance at End of Period	$ 89,221

Collaboration and Profit-Shar_5

Collaboration and Profit-Sharing Agreements - Contract Assets and Liability (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Change in contract asset and contract liability balances
Amounts included in deferred revenue at the beginning of the period	$ 5,706

Stock-Based Compensation - Expe

Stock-Based Compensation - Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Stock-based compensation disclosures
Compensation expense	$ 13,526	$ 5,417	$ 25,730	$ 11,637
Research and development
Stock-based compensation disclosures
Compensation expense	4,171	2,673	8,137	5,730
General and administrative
Stock-based compensation disclosures
Compensation expense	$ 9,355	$ 2,744	$ 17,593	$ 5,907

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock and Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Weighted Average Grant Date Fair Value
Compensation expense	$ 13,526	$ 5,417	$ 25,730	$ 11,637
Restricted Stock
Changes in unvested restricted stock
Unvested restricted shares, beginning of period (in shares)			507,450
Issued (in shares)			601,767
Vested (in shares)			(117,187)
Forfeited (in shares)			(131,434)
Unvested restricted shares, end of period(in shares)	860,596		860,596		507,450
Weighted Average Grant Date Fair Value
Balance, beginning of period			$ 27.35
Issued (in dollars per share)			47.84
Vested (in dollars per share)			27.42
Forfeited (in dollars per share)			38.40
Balance, ending of period	$ 40.54		$ 40.54		$ 27.35
Unrecognized stock-based compensation expense	$ 23,300		$ 23,300
Period for recognition			2 years 3 months 18 days
Performance based awards
Changes in unvested restricted stock
Issued (in shares)			226,747
Stock options
Weighted Average Grant Date Fair Value
Unrecognized stock-based compensation expense	$ 38,800		$ 38,800
Period for recognition			2 years 7 months 6 days
Changes in unvested stock options
Outstanding, beginning of period (in shares)			3,912,257
Granted (in shares)			1,133,470
Exercised (in shares)			(1,131,135)
Cancelled (in shares)			(661,719)
Outstanding, end of period (in shares)	3,252,873		3,252,873		3,912,257
Exercisable (in shares)	1,254,471		1,254,471
Outstanding, beginning of period (in dollars per share)			$ 27.26
Granted (in dollars per share)			44.48
Exercised (in dollars per share)			25.26
Cancelled (in dollars per share)			28.82
Outstanding, end of period (in dollars per share)	$ 33.64		33.64		$ 27.26
Exercisable (in dollar per share)	$ 28.17		$ 28.17
Remaining contractual life			8 years 1 month 6 days		7 years 10 months 24 days
Exercisable, remaining contractual life			7 years 2 months 12 days
Aggregate intrinsic value	$ 75,413		$ 75,413		$ 167,640
Exercisable, aggregated intrinsic value	$ 35,714		$ 35,714
Stock options | Chief Executive Officer | Vesting Provision One
Changes in unvested stock options
Granted (in shares)			196,637
Stock options | Chief Executive Officer | Vesting Provision Two
Changes in unvested stock options
Granted (in shares)			341,978

Net Income (Loss) per Share - A

Net Income (Loss) per Share - Anti-dilutive (Details) - shares	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Potentially dilutive securities
Anti-dilutive common stock equivalent shares	4,113,469	4,495,856
Restricted Stock
Potentially dilutive securities
Anti-dilutive common stock equivalent shares	860,596	516,131
Stock options
Potentially dilutive securities
Anti-dilutive common stock equivalent shares	3,252,873	3,979,725

Uncategorized Items - edit-2021

Label	Element	Value
Fair Value Measurements Recurring [Member] | Money Market Funds [Member]
Restricted Cash and Cash Equivalents	us-gaap_RestrictedCashAndCashEquivalents	$ 3,877,000
Restricted Cash and Cash Equivalents	us-gaap_RestrictedCashAndCashEquivalents	3,877,000
Fair Value Inputs Level1 [Member] | Fair Value Measurements Recurring [Member] | Money Market Funds [Member]
Restricted Cash and Cash Equivalents	us-gaap_RestrictedCashAndCashEquivalents	3,877,000
Restricted Cash and Cash Equivalents	us-gaap_RestrictedCashAndCashEquivalents	$ 3,877,000