Replimune (REPL) 10-Q 6 Aug 21 2022 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Jun. 30, 2021	Aug. 02, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	001-38596
Entity Registrant Name	REPLIMUNE GROUP, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-2082553
Entity Address, Address Line One	500 Unicorn Park
Entity Address, City or Town	Woburn
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01801
City Area Code	781
Local Phone Number	222-9600
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	REPL
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		46,772,263
Entity Central Index Key	0001737953
Amendment Flag	false
Current Fiscal Year End Date	--03-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021
Current assets:
Cash and cash equivalents	$ 192,528	$ 182,518
Short-term investments	265,803	293,784
Research and development incentives receivable	2,968	2,953
Prepaid expenses and other current assets	3,264	4,492
Total current assets	464,563	483,747
Property, plant and equipment, net	7,176	7,442
Research and development incentives receivable, non-current	781	0
Restricted cash	1,636	1,636
Right-to-use asset - operating leases	5,653	5,751
Right-to-use asset - financing leases	43,915	44,522
Total assets	523,724	543,098
Current liabilities:
Accounts payable	2,382	2,355
Accrued expenses and other current liabilities	9,186	8,735
Operating lease liabilities, current	975	970
Financing lease liabilities, current	2,506	2,487
Total current liabilities	15,049	14,547
Operating lease liabilities, non-current	4,978	5,078
Financing lease liabilities, non-current	24,673	24,745
Total liabilities	44,700	44,370
Commitments and contingencies (Note 12)
Stockholders' equity
Common stock, $0.001 par value; 150,000,000 shares authorized as of June 30, 2021 and March 31, 2021; 46,730,451 and 46,566,481 shares issued and outstanding as of June 30, 2021 and March 31, 2021, respectively	47	47
Additional paid-in capital	699,666	692,243
Accumulated deficit	(220,479)	(193,168)
Accumulated other comprehensive loss	(210)	(394)
Total stockholders' equity	479,024	498,728
Total liabilities and stockholders' equity	$ 523,724	$ 543,098

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2021	Mar. 31, 2021
Stockholders' Equity Attributable to Parent [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, issued (in shares)	46,730,451	46,566,481
Common stock, outstanding (in shares)	46,730,451	46,566,481

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating expenses:
Research and development	$ 18,554	$ 12,157
General and administrative	8,827	5,676
Total operating expenses	27,381	17,833
Loss from operations	(27,381)	(17,833)
Other income (expense):
Research and development incentives	788	686
Investment income	92	527
Interest expense on finance lease liability	(558)	(561)
Interest expense on debt obligations	0	(284)
Other (expense) income	(252)	(28)
Total other (expense) income, net	70	340
Net loss attributable to common stockholders	$ (27,311)	$ (17,493)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.53)	$ (0.44)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.53)	$ (0.44)
Weighted average common shares outstanding, basic (in shares)	51,910,331	39,862,319
Weighted average common shares outstanding, diluted (in shares)	51,910,331	39,862,319

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (27,311)	$ (17,493)
Other comprehensive loss:
Foreign currency translation gain (loss)	224	(12)
Net unrealized (loss) gain on short-term investments, net of tax of $0	(40)	(196)
Comprehensive loss	$ (27,127)	$ (17,701)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - Parenthetical	3 Months Ended
	Jun. 30, 2021USD ($)
Statement of Comprehensive Income [Abstract]
Net unrealized (loss) gain on short-term investments, net of tax of $0	$ 0

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive loss
Balance (in shares) at Mar. 31, 2020		36,668,743
Balance at Mar. 31, 2020	$ 183,718	$ 37	$ 296,961	$ (112,298)	$ (982)
Increase (decrease) in Stockholders' Equity
Issuance of prefunded warrants to purchase common stock, net of $2,100 issuance costs	32,900		32,900
Issuance of common stock, net of issuance costs and underwriter fees (in shares)		3,478,261
Issuance of common stock, net of issuance costs and underwriter fees of $5,117	74,882	$ 3	74,879
Foreign currency translation adjustment	(12)				(12)
Unrealized loss on short-term investments	(196)				(196)
Exercise of stock options (in shares)		133,416
Exercise of stock options	1,547		1,547
Stock-based compensation expense	2,468		2,468
Net loss	(17,493)			(17,493)
Balance (in shares) at Jun. 30, 2020		40,280,420
Balance at Jun. 30, 2020	277,814	$ 40	408,755	(129,791)	(1,190)
Balance (in shares) at Mar. 31, 2021		46,566,481
Balance at Mar. 31, 2021	498,728	$ 47	692,243	(193,168)	(394)
Increase (decrease) in Stockholders' Equity
Foreign currency translation adjustment	224				224
Unrealized loss on short-term investments	$ (40)				(40)
Exercise of stock options (in shares)	163,970	163,970
Exercise of stock options	$ 1,173		1,173
Stock-based compensation expense	6,250		6,250
Net loss	(27,311)			(27,311)
Balance (in shares) at Jun. 30, 2021		46,730,451
Balance at Jun. 30, 2021	$ 479,024	$ 47	$ 699,666	$ (220,479)	$ (210)

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) $ in Thousands	3 Months Ended
	Jun. 30, 2020USD ($)
Common stock | Follow-on public offering
Issuance costs and underwriter fees	$ 5,117
Prefunded warrants
Issuance costs and underwriter fees	$ 2,100

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (27,311)	$ (17,493)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	6,250	2,468
Depreciation and amortization	518	391
Net amortization of premiums and discounts on short-term investments	658	91
Noncash interest expense	0	63
Changes in operating assets and liabilities:
Research and development incentives receivable	(788)	(684)
Prepaid expenses and other current assets	1,228	(301)
Operating lease, right-of-use-asset	108	135
Finance lease, right-of-use-asset	607	607
Accounts payable	66	(224)
Accrued expenses and other current liabilities	456	(11)
Operating lease liabilities	(106)	(132)
Net cash used in operating activities	(18,314)	(15,090)
Cash flows from investing activities:
Purchases of property, plant and equipment	(291)	(932)
Purchase of short-term investments	(32,232)	(125,812)
Proceeds from sales and maturities of short-term investments	59,515	77,618
Net cash provided by (used in) investing activities	26,992	(49,126)
Cash flows from financing activities:
Proceeds from issuance of common stock in follow-on public offering, net of underwriting fees and discounts	0	75,199
Proceeds from issuance of prefunded warrants to purchase common stock, net of underwriting fees and discounts	0	32,900
Payment of issuance costs	0	(100)
Principal payment of finance lease obligation	(53)	(32)
Proceeds from exercise of stock options	1,173	1,547
Net cash provided by financing activities	1,120	109,514
Effect of exchange rate changes on cash, cash equivalents and restricted cash	212	(1)
Net increase (decrease) in cash, cash equivalents and restricted cash	10,010	45,297
Cash, cash equivalents and restricted cash at beginning of period	184,154	61,136
Cash, cash equivalents and restricted cash at end of period	194,164	106,433
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	0	221
Supplemental disclosure of non-cash investing and financing activities:
Net unrealized (loss) on short-term investments	(40)	(196)
Issuance costs included in accounts payable	0	317
Purchases of property and equipment included in accounts payable	39	64
Lease assets obtained in exchange for new operating lease liabilities	$ 0	$ 1,580

Summary of significant accounti

Summary of significant accounting policies	3 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Summary of significant accounting policies	Summary of significant accounting policiesPrinciples of consolidation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP, and include the accounts of the Company and its direct and indirect wholly owned subsidiaries, Replimune UK, Replimune US, Replimune Securities Corporation and Replimune (Ireland) Limited after elimination of all intercompany accounts and transactions. Use of estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, the accrual for research and development expenses and the valuation of stock-based awards. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. The full extent to which the COVID-19 pandemic, including evolving COVID-19 viral strains, will directly or indirectly impact our business, results of operations and financial condition, including, expenses, research and development costs and employee-related amounts, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19 and the actions taken to contain it or treat COVID-19. We have made estimates of the impact of COVID-19 within our financial statements and there may be changes to those estimates in future periods. Estimates are periodically reviewed in light of reasonable changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates or assumptions. Unaudited interim financial information The accompanying consolidated balance sheet as of June 30, 2021, the consolidated statements of operations, of comprehensive loss and of stockholders’ equity for the three months ended June 30, 2021 and 2020 and the consolidated statements of cash flows for the three months ended June 30, 2021 and 2020 are unaudited. The unaudited interim consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of June 30, 2021 and the results of its operations for the three months ended June 30, 2021 and 2020 and its cash flows for the three months ended June 30, 2021 and 2020. The financial data and other information disclosed in these consolidated notes related to the three months ended June 30, 2021 and 2020 are unaudited. The results for the three months ended June 30, 2021 are not necessarily indicative of results to be expected for the year ending March 31, 2022, any other interim periods or any future year or period. The financial information included herein should be read in conjunction with the financial statements and notes in the Company's Annual Report on Form 10-K for the year ended March 31, 2021. During the three months ended June 30, 2021, there have been no changes to the Company’s significant accounting policies as described in the Company's Annual Report on Form 10-K for the year ended March 31, 2021 which was filed with the Securities and Exchange Commission on May 20, 2021, except as described below. Recently adopted accounting pronouncements In December 2019, the FASB issued ASU No. 2019-12 Income Taxes (Topic 740)-Simplifying the Accounting for Income Taxes (ASU 2019-12) , which is intended to simplify the accounting for income taxes. ASU 2019-12 removes certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. ASU 2019-12 also amends other aspects of the guidance to help simplify and promote consistent application of GAAP. The new standard was effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We adopted ASU 2019-12 effective April 1, 2021. The adoption of ASU 2019-12 did not have a material impact on our consolidated financial statements. Recently issued accounting pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments- Credit Losses (Topic 326). The standard changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. Financial assets measured at amortized cost will be presented at the net amount expected to be collected by using an allowance for credit losses. In April 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments - Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, which clarifies and corrects certain unintended applications of the guidance contained in each of the amended Topics. Additionally, in May 2019, the FASB issued ASU No. 2019-05, Financial Instruments - Credit Losses (Topic 326), which provides an option to irrevocably elect to measure certain individual financial assets at fair value instead of amortized cost. The standard is effective for fiscal years and interim periods beginning after December 15, 2022. Early adoption is permitted for all periods beginning after December 15, 2018. The adoption of ASU 2016-13 is not expected to have a material impact on the Company's consolidated financial statements.

Nature of the business

Nature of the business	3 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the business	Nature of the business Replimune Group, Inc. (the “Company”) is a clinical-stage biotechnology company focused on the development of oncolytic immunotherapies to treat cancer. Replimune Group, Inc., whose predecessor was founded in 2015, is the parent company of its wholly owned, direct and indirect subsidiaries: Replimune Limited (“Replimune UK”); Replimune, Inc. (“Replimune US”); Replimune Securities Corporation; and Replimune (Ireland) Limited. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations and the ability to secure additional capital to fund operations. Product candidates currently under development will require significant additional research and development efforts, including preclinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance and reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. Basis of presentation The accompanying consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. The Company has incurred recurring losses since its inception, including net losses of $27,311 and $17,493 for the three months ended June 30, 2021 and 2020, respectively. In addition, as of June 30, 2021, the Company had an accumulated deficit of $220,479. The Company expects to continue to generate operating losses for the foreseeable future. As of the issuance date of these consolidated financial statements, the Company expects that its cash and cash equivalents and short-term investments will be sufficient to fund its operating expenses and capital expenditure requirements through at least 12 months from the issuance of the consolidated financial statements. Impact of the COVID-19 coronavirus In December 2019, a novel strain of coronavirus, which causes the disease known as COVID-19, was reported to have surfaced in Wuhan, China. Since then, COVID-19 coronavirus has spread globally. In March 2020, the World Health Organization declared the COVID-19 outbreak a pandemic and the U.S. government imposed travel restrictions on travel between the United States, Europe and certain other countries. The impact of this pandemic has been, and will likely continue to be, extensive in many aspects of society, which has resulted, and will likely continue to result, in significant disruptions to the global economy as well as businesses and capital markets around the world. In response to public health directives and orders and to help minimize the risk of the virus to employees, the Company has taken precautionary measures, including implementing work-from-home policies for the Company’s employees, other than those in its laboratory, those performing manufacturing functions and certain other employees as deemed appropriate from time to time. For those employees, the Company has implemented stringent safety measures designed to comply with applicable federal, state and local guidelines instituted in response to the COVID-19 pandemic. The Company has taken these and other precautionary steps while maintaining business continuity in order to continue to progress its programs. While there has been no prolonged material disruption to the Company’s business to date, the impact of the virus, including work-from-home policies, may negatively impact productivity, disrupt the Company’s business, and delay its preclinical research and clinical trial activities and its development program timelines, the magnitude of which will depend, in part, on the length and severity of the restrictions and other limitations on the Company’s ability to conduct its business in the ordinary course. Other impacts to the Company’s business may include temporary closures of its suppliers and disruptions or restrictions on its employees’ ability to travel. Any prolonged material disruption to the Company’s employees or suppliers could adversely impact the Company’s preclinical research and clinical trial activities, financial condition and results of operations, including its ability to obtain financing.

Fair value of financial assets

Fair value of financial assets and liabilities	3 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair value of financial assets and liabilities	Fair value of financial assets and liabilities The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements as of Level 1 Level 2 Level 3 Total Assets Money market funds $ — $ 179,008 $ — $ 179,008 US Government Agency bonds — 57,833 — 57,833 US Treasury bonds — 207,970 — 207,970 $ — $ 444,811 $ — $ 444,811 Fair Value Measurements as of Level 1 Level 2 Level 3 Total Assets Money market funds $ — $ 150,734 $ — $ 150,734 US Government Agency bonds — 67,012 — 67,012 US Treasury bonds — 226,772 — 226,772 $ — $ 444,518 $ — $ 444,518 The underlying securities held in the money market funds held by the Company are all government backed securities. During the three months ended June 30, 2021 and 2020, there were no transfers between levels. Valuation of cash equivalents and short-term investments Money market funds, U.S. Government Agency bonds and U.S. Treasury bonds were valued by the Company using quoted prices in active markets for similar securities, which represent a Level 2 measurement within the fair value hierarchy. Cash equivalents consisted of money market funds at June 30, 2021 and March 31, 2021.

Short-term investments

Short-term investments	3 Months Ended
	Jun. 30, 2021
Short-term Investments [Abstract]
Short-term investments	Short-term investments Short-term investments by investment type consisted of the following: June 30, 2021 Amortized Gross unrealized Gross unrealized Fair value US Government agency bonds $ 57,841 $ 5 $ (13) $ 57,833 US Treasury bonds 207,957 33 (20) 207,970 $ 265,798 $ 38 $ (33) $ 265,803 March 31, 2021 Amortized cost Gross unrealized gains Gross unrealized losses Fair value US Government agency bonds 67,017 12 (17) 67,012 US Treasury bonds 226,722 55 (5) 226,772 $ 293,739 $ 67 $ (22) $ 293,784

Property, plant and equipment,

Property, plant and equipment, net	3 Months Ended
	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Property, plant and equipment, net	Property, plant and equipment, net Property, plant and equipment, net consisted of the following: June 30, 2021 March 31, 2021 Office equipment $ 833 $ 830 Computer equipment 1,697 1,695 Plant and laboratory equipment 6,653 6,369 Leasehold improvements 785 784 Construction in progress 374 412 10,342 10,090 Less: Accumulated depreciation and amortization (3,166) (2,648) $ 7,176 $ 7,442 Depreciation and amortization expense was $518 and $391 for the three months ended June 30, 2021 and 2020, respectively. Depreciation and amortization expense are recorded within research and development and general and administrative expenses in the consolidated statement of operations.

Accrued expenses and other curr

Accrued expenses and other current liabilities	3 Months Ended
	Jun. 30, 2021
Accrued Liabilities and Other Liabilities [Abstract]
Accrued expenses and other current liabilities	Accrued expenses and other current liabilities Accrued expenses and other current liabilities consisted of the following: June 30, 2021 March 31, 2021 Accrued research and development costs $ 4,618 $ 3,862 Accrued compensation and benefits costs 3,325 3,952 Accrued professional fees 445 407 Other 798 514 $ 9,186 $ 8,735

Long-term debt

Long-term debt	3 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Long-term debt	Long-term debt For the periods ended June 30, 2021 and March 31, 2021, there are no debt balances outstanding as the Company entered a payoff letter in the prior fiscal year. Hercules Loan Agreement On August 8, 2019, (the “Closing Date”) the Company and certain of its affiliates entered into a Loan and Security Agreement (as amended, the “Hercules Loan Agreement”) with Hercules Capital, Inc. (“Hercules”) pursuant to which Hercules agreed to make available to the Company a secured term loan facility in the amount of $30,000 (the “Term Loan Facility”), subject to certain terms and conditions. The Company borrowed $10,000 under the Hercules Loan Agreement in one advance as a single tranche term loan on the Closing Date upon which the Company paid a $225 facility charge and incurred $130 in additional closing and legal fees. On June 1, 2020, the Company entered into the First Amendment to the Hercules Loan Agreement (the “Hercules First Amendment”), to, among other things, increase the aggregate principal amount of the secured term loan facility from $30,000 to $40,000. Pursuant to the Hercules First Amendment, subject to the achievement of certain milestones, the Company could have borrowed three tranches of up to $10,000 between October 1, 2020 and December 15, 2020, July 1, 2020 and June 30, 2021, and July 1, 2021 and December 15, 2021, respectively. The Company incurred $100 in additional closing and legal fees in connection with Hercules First Amendment which were capitalized and will be amortized as part of the effective yield. On December 15, 2020, the Company entered into a payoff letter with respect to the Hercules Loan Agreement (the "Payoff Letter"), which resulted in a loss on extinguishment of debt of $913 including both cash and non-cash expense. Pursuant to the Payoff Letter, the Company paid a total of $10,839 to Hercules, representing $10,000 in outstanding principal, $495 end of term charge, $300 early termination fee due and $44 in accrued interest owed to Hercules under the Hercules Loan Agreement. In connection with the execution of the Payoff Letter and the repayment of the Company’s outstanding obligations under the Hercules Loan Agreement, the Hercules Loan Agreement and the related loan documents were terminated. The Term Loan Facility was secured by substantially all of the Company’s assets, but excluding its intellectual property, and subject to certain exceptions and exclusions. All liens on the Company’s assets held by Hercules were released in connection with the execution of the Payoff Letter. In connection with entering into the Hercules Loan Agreement, the Company paid Hercules $355 of upfront fees, including closing costs and legal fees associated with entering into the agreement, which were recorded as a debt discount. In connection with entering into the Hercules First Amendment, the Company paid $100 of upfront fees, including closing costs and legal fees associated with entering into the amendment, which were recorded as debt discount. The Company recognized aggregate interest expense under the Hercules Loan Agreement of $0 and $284 during the three months ended June 30, 2021 and June 30, 2020, respectively, which included non-cash interest expense of $0 and $63. Non-cash interest expense related to the amortization of the debt discount of $0 and $27, and the accretion of the final payment of $0 and $36 for the three months ended June 30, 2021 and June 30, 2020, respectively.

Stockholders' equity

Stockholders' equity	3 Months Ended
	Jun. 30, 2021
Stockholders' Equity Note [Abstract]
Stockholders' equity	Stockholders’ equity Common stock As of June 30, 2021 and March 31, 2021, the Company’s certificate of incorporation, as amended and restated, authorized the Company to issue up to 150,000,000 shares of common stock, par value $0.001 per share. As of June 30, 2021 and March 31, 2021, the Company had reserved 14,408,145 and 14,572,115 shares of common stock for the exercise of outstanding stock options and the vesting of restricted share units, the number of shares remaining available for grant under the Company’s 2018 Omnibus Incentive Compensation Plan and the Company’s Employee Stock Purchase Plan (see Note 9) and the exercise of the outstanding warrants to purchase shares of common stock, respectively. Undesignated preferred stock As of June 30, 2021, the Company’s certificate of incorporation, as amended and restated, authorized the Company to issue up to 10,000,000 shares of undesignated preferred stock, par value $0.001 per share. There were no undesignated preferred shares issued or outstanding as of June 30, 2021. ATM program In August 2019, the Company entered into a Sales Agreement (as amended, the “2019 Sales Agreement”) with SVB Leerink LLC (the “Agent”), pursuant to which the Company could sell, from time to time, at its option, up to an aggregate amount of $75,000 of shares of the Company’s common stock, $0.001 par value per share, through the Agent, as the Company’s sales agent. In June 2020, the 2019 Sales Agreement was amended to reduce the aggregate offering amount under the 2019 Sales Agreement from $75,000 of shares to $30,000 of shares. On August 11, 2020, the 2019 Sales Agreement was terminated by the execution by the Company and the Agent of a new sales agreement, which was subsequently amended on October 21, 2020 (as amended, the “2020 Sales Agreement”). Under the 2020 Sales Agreement the Company may sell, from time to time, at its option, up to an aggregate of $62,500 of shares of the Company’s common stock, $0.001 par value per share (the “Shares”), through the Agent, as the Company’s sales agent. Any Shares to be offered and sold under the 2020 Sales Agreement will be issued and sold (i) by methods deemed to be an “at the market offering” (“ATM”) as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended or in negotiated transactions, if authorized by the Company, and (ii) pursuant to, and only upon the effectiveness of, a registration statement on Form S-3 filed by the Company with the Securities and Exchange Commission on August 11, 2020 for an offering of up to $350,000 of various securities, including shares of the Company’s common stock, preferred stock, debt securities, warrants and/or units for sale to the public in one or more public offerings. Subject to the terms of the 2020 Sales Agreement, the Agent will use reasonable efforts to sell the Shares from time to time, based upon the Company’s instructions (including any price, time or size limits or other customary parameters or conditions the Company may impose). The Company cannot provide any assurances that it will issue any Shares pursuant to the 2020 Sales Agreement. The Company will pay the Agent a commission of up to 3.0% of the gross proceeds from the sale of the Shares, if any. The Company has also agreed to provide the Agent with customary indemnification rights. During the year ended March 31, 2020, the Company issued and sold 287,559 shares, of common stock under the 2019 Sales Agreement, for gross proceeds of $4,568 less offering fees of $137 for net proceeds of $4,431 under the ATM. The Company did not issue or sell any shares under the 2020 Sales Agreement during the quarter ended June 30, 2021 or during the year ended March 31, 2021. Equity offerings In November 2019, pursuant to an underwriting agreement (the “November 2019 Underwriting Agreement”) with J.P. Morgan Securities LLC and SVB Leerink LLC, as representatives of the several underwriters named therein (the “November 2019 Underwriters”), the Company issued and sold to the November 2019 Underwriters (a) 4,516,561 shares of the Company’s common stock (the “November 2019 Shares”), inclusive of the November 2019 Underwriters partially exercised 30-day option and purchased an additional 838,530 shares of the Company’s common stock, and (b) pre-funded warrants to purchase 2,200,000 shares of the Company’s common stock (the “November 2019 Pre-Funded Warrants”). The November 2019 shares were sold to the November 2019 Underwriters (the “November 2019 Offering”) at the public offering price of $13.61 per share and the November 2019 Pre-Funded Warrants were sold at a public offering price of $13.6099 per November 2019 Pre-Funded Warrant, which represented the per share public offering price for the November 2019 Shares less a $0.0001 per share exercise price for each such November 2019 Pre-Funded Warrant. The Company received aggregate net proceeds of approximately $85,598 in the November 2019 Offering, after deducting underwriting discounts, commissions and other offering expenses payable by the Company of approximately $5,814. Funds affiliated with Redmile Group, LLC purchased all of the November 2019 Pre-Funded Warrants. The November 2019 Pre-Funded Warrants are exercisable at any time after the date of issuance. A holder of November 2019 Pre-Funded Warrants may not exercise the November 2019 Pre-Funded Warrant if the holder, together with its affiliates, would beneficially own more than 9.99% of the number of shares of the Company’s common stock outstanding immediately after giving effect to such exercise. In June 2020, pursuant to an underwriting agreement (the “June 2020 Underwriting Agreement”) with J.P. Morgan Securities LLC and SVB Leerink LLC, as representatives of the several underwriters named therein (the "June 2020 Underwriters”), the Company sold to the June 2020 Underwriters (a) 3,478,261 shares of the Company’s common stock (the “June 2020 Shares”), inclusive of the underwriters 30-day option to purchase up to an additional 652,173 shares of the Company's common stock, and (b) pre-funded warrants to purchase 1,521,738 shares of the Company’s common stock (the “June 2020 Pre-Funded Warrants”). The June 2020 Shares of the Company's common stock were sold to the June 2020 Underwriters at the public offering price of $23.00 per share and the June 2020 Pre-Funded Warrants were sold at a public offering price of $22.9999 per June 2020 Pre-Funded Warrant, which represented the per share public offering price for the June 2020 shares less a $0.0001 per share exercise price for each such June 2020 Pre-Funded Warrant. The Company received aggregate net proceeds of approximately $107,782 after deducting underwriting discounts, commissions and other offering expenses payable by the Company of approximately $7,217. Funds affiliated with Redmile Group, LLC and funds affiliated with a second institutional investor purchased all of the June 2020 Pre-Funded Warrants. The June 2020 Pre-Funded Warrants are exercisable at any time after the date of issuance. A holder of June 2020 Pre-Funded Warrants may not exercise the June 2020 Pre-Funded Warrants if the holder, together with its affiliates, would beneficially own more than 9.99% of the number of shares of the Company’s common stock outstanding immediately after giving effect to such exercise. A holder of June 2020 Pre-Funded Warrants may increase or decrease this percentage up to 19.99% by providing at least 61 days’ prior notice to the Company. In October 2020, pursuant to an underwriting agreement with J.P. Morgan Securities LLC and SVB Leerink LLC, as representatives of the several underwriters named therein, the Company issued and sold to the underwriters (a) 5,625,000 shares of the Company’s common stock, inclusive of the underwriters 30-day option to purchase up to an additional 937,500 shares of the Company’s common stock, and (b) pre-funded warrants to purchase 1,562,500 shares of the Company’s common stock (the “October 2020 Pre-Funded Warrants”). The shares of the Company’s common stock were sold to the underwriters at the public offering price of $40.00 per share and the October 2020 Pre-Funded Warrants were sold at a public offering price of $39.9999 per October 2020 Pre-Funded Warrant, which represented the per share public offering price for the Company’s common stock less a $0.0001 per share exercise price for each October 2020 Pre-Funded Warrant. The Company received aggregate net proceeds of approximately $269,975 after deducting underwriting discounts, commissions and other offering expenses payable by the Company of approximately $17,525. Funds affiliated with Redmile Group, LLC and funds affiliated with a second institutional investor purchased all of the October 2020 Pre-Funded Warrants. The October 2020 Pre-Funded Warrants are exercisable at any time after the date of issuance. A holder of October 2020 Pre-Funded Warrants may not exercise the October 2020 Pre-Funded Warrants if the holder, together with its affiliates, would beneficially own more than 9.99% of the number of shares of the Company’s common stock outstanding immediately after giving effect to such exercise. A holder of October 2020 Pre-Funded Warrants may increase or decrease this percentage up to 19.99% by providing at least 61 days’ prior notice to the Company. Other than as set forth in Note 9 and Note 10 to these consolidated financial statements, the 5,284,238 Pre-Funded Warrants are not included in the number of issued and outstanding shares of the Company’s common stock set forth herein. As of June 30, 2021, none of the November 2019 Pre-Funded Warrants, the June 2020 Pre-Funded Warrants, or the October 2020 Pre-Funded Warrants had been exercised.

Stock-based compensation

Stock-based compensation	3 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Stock-based compensation	Stock-based compensation Stock-based compensation expense Stock-based compensation expense was classified in the consolidated statements of operations as follows: Three Months Ended 2021 2020 Research and development $ 2,458 $ 1,000 General and administrative 3,792 1,468 $ 6,250 $ 2,468 The following table summarizes stock-based compensation expense by award type for the three months ended June 30, 2021 and 2020: Three Months Ended 2021 2020 Stock options $ 5,175 $ 2,468 Restricted stock units 1,075 — $ 6,250 $ 2,468 2015 Enterprise Mana gement Incentive Share Option Plan The 2015 Enterprise Management Incentive Share Option Plan of Replimune UK (the “2015 Plan”) provided for Replimune UK to grant incentive stock options, non-statutory stock options, stock awards, stock units, stock appreciation rights and other stock-based awards. Incentive stock options are granted only to the Company’s employees, including officers and directors who are also employees. Non-statutory stock options are granted to employees, members of the board of directors, outside advisors and consultants of the Company. 2017 Equity Compensation Plan In July 2017, in conjunction with the Reorganization, the 2015 Plan was terminated, and all awards were cancelled with replacement awards issued under the 2017 Equity Compensation Plan (the “2017 Plan”). Subsequent to the Reorganization, no additional grants will be made under the 2015 Plan and any outstanding awards under the 2015 Plan will continue with their original terms. The Company concluded that the cancellation of the 2015 Plan and issuance of replacement awards under the 2017 Plan was a modification with no change in the material rights and preferences and therefore no recorded change in the fair value of each respective award. The Company’s 2017 Plan provides for the Company to grant incentive stock options or non-statutory stock options, stock awards, stock units, stock appreciation rights and other stock-based awards. Incentive stock options may be granted only to the Company’s employees, including officers and directors who are also employees. Restricted stock awards and non-statutory stock options may be granted to employees, officers, members of the board of directors, advisors and consultants of the Company. The maximum number of common shares that may be issued under the 2017 Plan was 2,659,885, of which none remained available for future grants as of June 30, 2021. Shares with respect to which awards have expired, terminated, surrendered or cancelled under the 2017 Plan without having been fully exercised will be available for future awards under the 2017 Plan. In addition, shares of common stock that are tendered to the Company by a participant to exercise an award are added to the number of shares of common stock available for the grant of awards. 2018 Omnibus Incentive Compensation Plan On July 9, 2018, the Company’s board of directors adopted, and the Company’s stockholders approved the 2018 Omnibus Incentive Compensation Plan (the “2018 Plan”), which became effective immediately prior to the effectiveness of the registration statement for the Company’s initial public offering. The 2018 Plan provides for the issuance of incentive stock options, non-qualified stock options, stock awards, stock units, stock appreciation rights and other stock-based awards. The number of shares initially reserved for issuance under the 2018 Plan is 3,617,968 shares. If any options or stock appreciation rights, including outstanding options and stock appreciation rights granted under the 2017 Plan (up to 2,520,247 shares), terminate, expire, or are canceled, forfeited, exchanged, or surrendered without having been exercised, or if any stock awards, stock units or other stock-based awards, including outstanding awards granted under the 2017 Plan, are forfeited, terminated, or otherwise not paid in full in shares of common stock, the shares of the Company’s common stock subject to such grants will be available for purposes of our 2018 Plan. The number of shares reserved for issuance under the 2018 Plan will increase automatically on the first day of each April equal to 4.0% of the total number of shares of Company stock outstanding on the last trading day in the immediately preceding fiscal year, or such lesser amount as determined by the Board. On April 1, 2021, the number of shares reserved for issuance under the 2018 Plan automatically increased by 2,074,028 shares pursuant to the terms of the 2018 Plan and based on total number of shares of Company stock outstanding on March 31, 2021, including the November 2019 Pre-Funded Warrants, the June 2020 Pre-Funded Warrants and the October 2020 Pre-Funded Warrants. On April 1, 2020, the number of shares reserved for issuance under the 2018 Plan automatically increased by 1,466,749 shares pursuant to the terms of the 2018 Plan. As of June 30, 2021, 1,587,935 shares remained available for future grants under the 2018 Plan. The 2015 Plan, the 2017 Plan and the 2018 Plan was administered by the board of directors or, at the discretion of the board of directors, by a committee of the board of directors. However, the board of directors shall administer and approve all grants made to non-employee directors. The exercise prices, vesting and other restrictions are determined at the discretion of the board of directors, except that the exercise price per share of incentive stock options may not be less than 100% of the fair market value of the common stock on the date of grant (or 110% of fair value in the case of an award granted to employees who hold more than 10% of the total combined voting power of all classes of stock at the time of grant) and the term of stock options may not be greater than five years for an incentive stock option granted to a 10% stockholder and greater than ten years for all other options granted. Stock options awarded under both plans expire ten years after the grant date, unless the board of directors sets a shorter term. Vesting periods for both plans are determined at the discretion of the board of directors. Incentive stock options granted to employees and non-statutory options granted to employees, officers, members of the board of directors, advisors, and consultants of the Company typically vest over four years. In 2021 the board of directors initiated the award of restricted stock units, or RSUs, under the 2018 Plan in addition to stock option awards available as part of the Company's equity incentive for employees, officers, advisors and consultants of the Company. The RSUs typically vest over four roughly equal installments on the anniversary date of the designated vesting date that is in closest proximity to the date of grant. Employee Stock Purchase Plan On July 9, 2018, the Company’s board of directors adopted and the Company’s stockholders approved the Employee Stock Purchase Plan (the “ESPP”), which became effective immediately prior to the effectiveness of the registration statement for the Company’s IPO. The total shares of common stock initially reserved for issuance under the ESPP is limited to 348,612 shares. In addition, as of the first trading day of each fiscal year during the term of the ESPP (excluding any extensions), an additional number of shares of the Company’s common stock equal to 1% of the total number of shares outstanding on the last trading day in the immediately preceding fiscal year, including the November 2019 Pre-Funded Warrants, the June 2020 Pre-Funded Warrants, and the October 2020 Pre-Funded Warrants, or 697,224 shares, whichever is less (or such lesser amount as determined by the Company’s board of directors) will be added to the number of shares authorized under the ESPP. In accordance with the terms of the ESPP, on April 1, 2021 and 2020, the number of shares reserved for issuance under the ESPP automatically increased by 518,507 and 366,687 shares respectively, for a total of 1,550,375 shares reserved for the ESPP. If the total number of shares of common stock to be purchased pursuant to outstanding purchase rights on any particular date exceed the number of shares then available for issuance under the ESPP, then the plan administrator will allocate the available shares pro-rata and refund any excess payroll deductions or other contributions to participants. The Company’s ESPP is not currently active. Out-of-Plan Inducement Grant In May 2021, the Company granted an equity award to a newly hired executive as an inducement material to enter into employment with the Company. The grant constitutes an "employment inducement grant" in accordance with Rule 5635(c)(4) of the Nasdaq Listing Rules, and the grant was not issued under the Replimune Group, Inc. 2018 Omnibus Incentive Compensation Plan or any of the other stock incentive plans described above. The inducement grant included a nonqualified stock option to purchase up to 125,000 shares of the Company's common stock, as well as a restricted stock unit grant representing 88,333 shares of its common stock. These stock option and restricted stock unit inducement grants have terms and conditions consistent with those set forth under the 2018 Plan and vest under the same respective vesting schedules as stock option and restricted stock unit awards granted under the 2018 Plan. The inducement grant is included in the stock option and RSU award tables below. Stock option valuation The fair value of stock option grants is estimated using the Black-Scholes option-pricing model. As the Company has limited company-specific historical and implied volatility information, the expected stock volatility is based on a combination of Replimune volatility and the historical volatility of a set of publicly traded peer companies. For options with service-based vesting conditions, the expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The expected term of stock options granted to non-employees is equal to the contractual term of the option award. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The following table presents, on a weighted-average basis, the assumptions that the Company used to determine the grant-date fair value of stock options granted to employees and directors: Three Months Ended 2021 2020 Risk-free interest rate 1.12 % 1.24 % Expected term (in years) 6.0 6.5 Expected volatility 80.2 % 75.0 % Expected dividend yield 0 % 0 % Stock options The following table summarizes the Company’s stock option activity: Number of Weighted Weighted Aggregate Outstanding as of March 31, 2021 6,460,184 $ 13.26 7.95 $ 116,193 Granted 1,224,812 $ 32.54 Exercised (163,970) $ 7.16 $ 4,174 Cancelled (109,346) $ 26.98 Outstanding as of June 30, 2021 7,411,680 $ 16.39 7.93 $ 164,305 Options exercisable as of March 31, 2021 2,698,708 $ 8.38 6.79 $ 59,717 Options exercisable as of June 30, 2021 3,340,279 $ 8.97 6.82 $ 98,367 As of June 30, 2021, there was $55.5 million of unrecognized compensation cost related to unvested common stock options, which is expected to be recognized over a weighted average period of 2.82 years. The weighted average grant-date fair value of stock options granted during the three months ended June 30, 2021 and 2020 was $22.29 and $6.94, respectively. The aggregate intrinsic value of stock options exercised during the three months ended June 30, 2021 was $4.2 million. Restricted stock units A summary of the changes in the Company's RSUs during the three months ended June 30, 2021 is as follows: Number of Restricted Shares Weighted Outstanding as of March 31, 2021 15,975 34.15 Granted 657,431 32.84 Vested — — Cancelled (4,298) 31.58 Outstanding as of June 30, 2021 669,108 32.88

Net loss per share

Net loss per share	3 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Net loss per share	Net loss per share Basic and diluted net loss per share attributable to common stockholders was calculated as follows: Three Months Ended June 30, 2021 2020 Numerator: Net loss attributable to common stockholders $ (27,311) $ (17,493) Denominator: Weighted average common shares outstanding, basic and diluted 51,910,331 39,862,319 Net loss per share attributable to common stockholders, basic and diluted $ (0.53) $ (0.44) The November 2019 Pre-Funded Warrants, the June 2020 Pre-Funded Warrants and the October 2020 Pre-Funded Warrants are included as outstanding common stock in the calculation of basic and diluted net loss per share attributable to common stockholders. The Company’s potentially dilutive securities, which include stock options and warrants to purchase shares of series seed preferred stock, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: Three Months Ended June 30, 2021 2020 Options to purchase common stock 7,411,680 6,510,522 Warrants to purchase common stock 497,344 497,344 7,909,024 7,007,866

Significant agreements

Significant agreements	3 Months Ended
	Jun. 30, 2021
Significant agreements
Significant agreements	Significant agreements Agreement with Bristol-Myers Squibb Company In February 2018, the Company entered into an agreement with Bristol-Myers Squibb Company (“BMS”). Pursuant to the agreement, BMS will provide to the Company, at no cost, a compound for use in the Company’s ongoing clinical trial of RP1. Under the agreement, the Company will sponsor, fund and conduct the clinical trial in accordance with an agreed-upon protocol. BMS granted the Company a non-exclusive, non-transferrable, royalty-free license (with a right to sublicense) under its intellectual property to its compound in the clinical trial and agreed to supply its compound, at no cost to the Company, for use in the clinical trial. In January 2020, this agreement was expanded to cover an additional cohort of 125 patients with anti-PD-1 failed melanoma. Unless earlier terminated, the agreement will remain in effect until (i) the completion of the clinical trial, (ii) all related clinical trial data have been delivered to both parties and (iii) the completion of any statistical analyses and bioanalyses contemplated by the clinical trial protocol or any analysis otherwise agreed upon by the parties. The agreement may be terminated by either party (i) in the event of an uncured material breach by the other party, (ii) in the event the other party is insolvent or in bankruptcy proceedings or (iii) for safety reasons. Upon termination, the licenses granted to the Company to use BMS’s compound in the clinical trial will terminate. In April 2019, the Company entered into a separate agreement with BMS on terms similar to the terms set forth in the agreement described above, pursuant to which BMS will provide to the Company, at no cost, nivolumab for use in the Company’s Phase 1 clinical trial of RP2 in combination with nivolumab. Agreement with Regeneron Pharmaceuticals, Inc . In May 2018, the Company entered into an agreement with Regeneron Pharmaceuticals, Inc. (“Regeneron”). The Company and Regeneron are each independently developing compounds for the treatment of certain tumor types. Pursuant to the agreement, the Company and Regeneron will undertake one or more clinical trials using a combination of the compounds being developed by each entity. Under the agreement, each study will be conducted under terms set out in a separately agreed upon study plan that will identify the name of the sponsor and which party will manage the particular clinical trial, and include the protocol, the budget and a schedule of clinical obligations. In June 2018, under the terms of the agreement between the Company and Regeneron, the parties agreed to the first study plan. The Company and Regeneron have agreed to the protocol, budget, sample testing and clinical obligations schedule under the study plan. Development and supply costs associated with the study plan will be split equally between the Company and Regeneron. Pursuant to the terms of the agreement, each party granted the other party a non-exclusive license under its respective intellectual property and agreed to contribute the necessary resources needed to fulfill its respective obligations, in each case, under the terms of the agreed-upon or to-be agreed upon study plans. Development costs of a particular clinical trial will be split equally between the Company and Regeneron in accordance with the agreed upon study plan. The agreement may be terminated by either party if (i) there is no active study plan for which a final study report has not been completed and the parties have not entered into a study plan for an additional clinical trial within a period of time after the delivery of the most recent final study report or (ii) in the event of a material breach. The agreement with Regeneron is accounted for under ASC 808, Collaborative Arrangements (“ASC 808”), as both parties are active participants and each party pays its own compound costs and share equally in development costs. The Company will account for costs incurred as part of the study, including costs to supply compounds for use in the study, as research and development expenses within the consolidated statement of operations. The Company will recognize any amounts received from Regeneron in connection with this agreement as an offset to research and development expense within the consolidated statement of operations. Under the terms of the agreement, on a quarterly basis the Company and Regeneron true-up costs of the study and make corresponding payments to the party that incurred the majority of the costs. During the three months ended June 30, 2021 and 2020, the Company did not make any payments under the terms of the agreement from Regeneron. As of June 30, 2021 and March 31, 2021, the Company recorded $1.4 million and $1.3 million of receivables from Regeneron in connection with this agreement in prepaid expenses and other current assets in the consolidated balance sheet, respectively.

Commitments and contingencies

Commitments and contingencies	3 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and contingencies Leases The Company leases real estate assets and equipment, and determination if an arrangement is a lease occurs at inception. For leases with terms greater than 12 months, the Company records a related right-of-use (“ROU”) asset and lease liability at the present value of lease payments over the term. Many leases include fixed rental escalation clauses, renewal options and/or termination options that are factored into the determination of lease payments when appropriate. The Company’s leases do not provide an implicit rate, and thus the Company estimated the incremental borrowing rate in calculating the present value of the lease payments. The Company has elected not to record a ROU asset and lease obligation for short-term leases (with terms less than 12 months) or separate non-lease components from associated lease components for its real estate lease assets. As a result, all contract consideration is allocated to the single lease component. The Company’s leases have remaining lease terms of eight years to eighteen years. Some of our leases include one or more options to renew with renewal terms that can extend the lease for additional years, or options to terminate the leases, both at the Company’s discretion. The Company’s lease terms include options to extend or terminate leases when the Company concludes it is reasonably certain that it would exercise those options. Lease expense for minimum lease payments is recognized on a straight-line basis based on the fixed components of a lease arrangement. The Company amortizes this expense over the term of the lease beginning with the date of initial possession, which is the date the Company can enter the leased space and begin to make improvements in preparation for its intended use. Variable lease components represent amounts that are not fixed in nature and are not tied to an index or rate, and are recognized as incurred. The table below presents the lease-related assets and liabilities recorded on the consolidated balance sheet as of June 30, 2021: Three Months Ended June 30, 2021 2020 Lease cost Finance lease costs: Amortization of right-to-use asset $ 607 $ 607 Interest on lease liabilities 558 561 Operating lease costs 242 230 Total lease cost $ 1,407 $ 1,398 The Company incurred finance lease amortization costs of $607 for both the three months ended June 30, 2021 and 2020, respectively, of which $518 and $517 are recognized in research and development expenses. In addition, the Company incurred interest expense on finance leases of $558 and $561, of which $468 and $471 are recognized in research and development for the three months ended June 30, 2021 and 2020, respectively. For both the three months ended June 30, 2021 and 2020, the Company recognized $89 of operating lease costs within general and administrative expenses. The following table summarizes the maturity of the Company’s lease liabilities on an undiscounted cash flow basis and a reconciliation to the operating and financing lease liabilities recognized on our balance sheet as of June 30, 2021: June 30, 2021 Operating leases Financing lease Total 2022 (remaining three months) $ 731 $ 1,876 $ 2,607 2023 982 2,562 3,544 2024 991 2,639 3,630 2025 1,000 2,718 3,718 2026 1,010 2,799 3,809 Thereafter 4,076 40,905 44,981 Total lease payments 8,790 53,499 62,289 Less: interest 2,837 26,320 29,157 Total lease liabilities $ 5,953 $ 27,179 $ 33,132 The following table provides lease disclosure as of June 30, 2021 and March 31, 2021: June 30, 2021 March 31, 2021 Leases Right-to-use operating lease asset $ 5,653 $ 5,751 Right-to-use finance lease asset 43,915 44,522 Total lease assets $ 49,568 $ 50,273 Operating lease liabilities, current $ 975 $ 970 Finance lease liabilities, current 2,506 2,487 Operating lease liabilities, non-current 4,978 5,078 Finance lease liabilities, non-current 24,673 24,745 Total lease liabilities $ 33,132 $ 33,280 The following table provides lease disclosure for the three months ended June 30, 2021 and 2020: Three Months Ended June 30, 2021 2020 Other information Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 242 $ 209 Operating cash flows from finance leases $ 558 $ 561 Financing cash flows from finance leases $ 53 $ 32 Right-to-use asset obtained in exchange for new operating lease liabilities $ — $ 1,580 Weighted-average remaining lease term - operating leases 8.6 years 9.8 years Weighted-average remaining lease term - financing leases 18.1 years 19.3 years Weighted-average discount rate - operating leases 9.9 % 10 % Weighted-average discount rate - financing leases 8.3 % 8 % The variable lease costs and short-term lease costs were insignificant for three months ended June 30, 2021 and 2020. Manufacturing commitments The Company has entered into an agreement with a contract manufacturing organization to provide clinical trial products. As of June 30, 2021 and March 31, 2021, the Company had committed to minimum payments under these arrangements totaling $1,600 and $1,651, respectively, through June 30, 2021. Indemnification agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its executive management team and its board of directors that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not aware of any claims under indemnification arrangements, and therefore it has not accrued any liabilities related to such obligations in its consolidated financial statements as of June 30, 2021 or March 31, 2021. Legal proceedings

Geographic information

Geographic information	3 Months Ended
	Jun. 30, 2021
Segments, Geographical Areas [Abstract]
Geographic information	Geographic information The Company operates in two geographic regions: the United States (Massachusetts) and the United Kingdom (Oxfordshire). Information about the Company’s long-lived assets held in different geographic regions is presented in the tables below: June 30, 2021 March 31, 2021 United States $ 6,654 $ 6,866 United Kingdom 522 576 $ 7,176 $ 7,442

Summary of significant accoun_2

Summary of significant accounting policies (Policies)	3 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Principles of consolidation	Principles of consolidationThe accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP, and include the accounts of the Company and its direct and indirect wholly owned subsidiaries, Replimune UK, Replimune US, Replimune Securities Corporation and Replimune (Ireland) Limited after elimination of all intercompany accounts and transactions.
Use of estimates	Use of estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, the accrual for research and development expenses and the valuation of stock-based awards. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. The full extent to which the COVID-19 pandemic, including evolving COVID-19 viral strains, will directly or indirectly impact our business, results of operations and financial condition, including, expenses, research and development costs and employee-related amounts, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19 and the actions taken to contain it or treat COVID-19. We have made estimates of the impact of COVID-19 within our financial statements and there may be changes to those estimates in future periods. Estimates are periodically reviewed in light of reasonable changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates or assumptions.
Unaudited interim financial information	Unaudited interim financial information The accompanying consolidated balance sheet as of June 30, 2021, the consolidated statements of operations, of comprehensive loss and of stockholders’ equity for the three months ended June 30, 2021 and 2020 and the consolidated statements of cash flows for the three months ended June 30, 2021 and 2020 are unaudited. The unaudited interim consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of June 30, 2021 and the results of its operations for the three months ended June 30, 2021 and 2020 and its cash flows for the three months ended June 30, 2021 and 2020. The financial data and other information disclosed in these consolidated notes related to the three months ended June 30, 2021 and 2020 are unaudited. The results for the three months ended June 30, 2021 are not necessarily indicative of results to be expected for the year ending March 31, 2022, any other interim periods or any future year or period. The financial information included herein should be read in conjunction with the financial statements and notes in the Company's Annual Report on Form 10-K for the year ended March 31, 2021. During the three months ended June 30, 2021, there have been no changes to the Company’s significant accounting policies as described in the Company's Annual Report on Form 10-K for the year ended March 31, 2021 which was filed with the Securities and Exchange Commission on May 20, 2021, except as described below.
Recently adopted accounting pronouncements and Recently issued accounting pronouncements	Recently adopted accounting pronouncements In December 2019, the FASB issued ASU No. 2019-12 Income Taxes (Topic 740)-Simplifying the Accounting for Income Taxes (ASU 2019-12) , which is intended to simplify the accounting for income taxes. ASU 2019-12 removes certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. ASU 2019-12 also amends other aspects of the guidance to help simplify and promote consistent application of GAAP. The new standard was effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We adopted ASU 2019-12 effective April 1, 2021. The adoption of ASU 2019-12 did not have a material impact on our consolidated financial statements. Recently issued accounting pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments- Credit Losses (Topic 326). The standard changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. Financial assets measured at amortized cost will be presented at the net amount expected to be collected by using an allowance for credit losses. In April 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments - Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, which clarifies and corrects certain unintended applications of the guidance contained in each of the amended Topics. Additionally, in May 2019, the FASB issued ASU No. 2019-05, Financial Instruments - Credit Losses (Topic 326), which provides an option to irrevocably elect to measure certain individual financial assets at fair value instead of amortized cost. The standard is effective for fiscal years and interim periods beginning after December 15, 2022. Early adoption is permitted for all periods beginning after December 15, 2018. The adoption of ASU 2016-13 is not expected to have a material impact on the Company's consolidated financial statements.
Leases	The Company leases real estate assets and equipment, and determination if an arrangement is a lease occurs at inception. For leases with terms greater than 12 months, the Company records a related right-of-use (“ROU”) asset and lease liability at the present value of lease payments over the term. Many leases include fixed rental escalation clauses, renewal options and/or termination options that are factored into the determination of lease payments when appropriate. The Company’s leases do not provide an implicit rate, and thus the Company estimated the incremental borrowing rate in calculating the present value of the lease payments. The Company has elected not to record a ROU asset and lease obligation for short-term leases (with terms less than 12 months) or separate non-lease components from associated lease components for its real estate lease assets. As a result, all contract consideration is allocated to the single lease component. The Company’s leases have remaining lease terms of eight years to eighteen years. Some of our leases include one or more options to renew with renewal terms that can extend the lease for additional years, or options to terminate the leases, both at the Company’s discretion. The Company’s lease terms include options to extend or terminate leases when the Company concludes it is reasonably certain that it would exercise those options. Lease expense for minimum lease payments is recognized on a straight-line basis based on the fixed components of a lease arrangement. The Company amortizes this expense over the term of the lease beginning with the date of initial possession, which is the date the Company can enter the leased space and begin to make improvements in preparation for its intended use. Variable lease components represent amounts that are not fixed in nature and are not tied to an index or rate, and are recognized as incurred.

Fair value of financial asset_2

Fair value of financial assets and liabilities (Tables)	3 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of company's financial assets and liabilities measured at fair value on a recurring basis	The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements as of Level 1 Level 2 Level 3 Total Assets Money market funds $ — $ 179,008 $ — $ 179,008 US Government Agency bonds — 57,833 — 57,833 US Treasury bonds — 207,970 — 207,970 $ — $ 444,811 $ — $ 444,811 Fair Value Measurements as of Level 1 Level 2 Level 3 Total Assets Money market funds $ — $ 150,734 $ — $ 150,734 US Government Agency bonds — 67,012 — 67,012 US Treasury bonds — 226,772 — 226,772 $ — $ 444,518 $ — $ 444,518

Short-term investments (Tables)

Short-term investments (Tables)	3 Months Ended
	Jun. 30, 2021
Short-term Investments [Abstract]
Schedule of short-term investments	Short-term investments by investment type consisted of the following: June 30, 2021 Amortized Gross unrealized Gross unrealized Fair value US Government agency bonds $ 57,841 $ 5 $ (13) $ 57,833 US Treasury bonds 207,957 33 (20) 207,970 $ 265,798 $ 38 $ (33) $ 265,803 March 31, 2021 Amortized cost Gross unrealized gains Gross unrealized losses Fair value US Government agency bonds 67,017 12 (17) 67,012 US Treasury bonds 226,722 55 (5) 226,772 $ 293,739 $ 67 $ (22) $ 293,784

Property, plant and equipment_2

Property, plant and equipment, net (Tables)	3 Months Ended
	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Schedule of property, plant and equipment, net	Property, plant and equipment, net consisted of the following: June 30, 2021 March 31, 2021 Office equipment $ 833 $ 830 Computer equipment 1,697 1,695 Plant and laboratory equipment 6,653 6,369 Leasehold improvements 785 784 Construction in progress 374 412 10,342 10,090 Less: Accumulated depreciation and amortization (3,166) (2,648) $ 7,176 $ 7,442

Accrued expenses and other cu_2

Accrued expenses and other current liabilities (Tables)	3 Months Ended
	Jun. 30, 2021
Accrued Liabilities and Other Liabilities [Abstract]
Schedule of accrued expenses and other current liabilities	Accrued expenses and other current liabilities consisted of the following: June 30, 2021 March 31, 2021 Accrued research and development costs $ 4,618 $ 3,862 Accrued compensation and benefits costs 3,325 3,952 Accrued professional fees 445 407 Other 798 514 $ 9,186 $ 8,735

Stock-based compensation (Table

Stock-based compensation (Tables)	3 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Schedule of stock-based compensation expense	Stock-based compensation expense was classified in the consolidated statements of operations as follows: Three Months Ended 2021 2020 Research and development $ 2,458 $ 1,000 General and administrative 3,792 1,468 $ 6,250 $ 2,468 The following table summarizes stock-based compensation expense by award type for the three months ended June 30, 2021 and 2020: Three Months Ended 2021 2020 Stock options $ 5,175 $ 2,468 Restricted stock units 1,075 — $ 6,250 $ 2,468
Schedule of assumptions used to determine the grant-date fair value of stock options granted	The following table presents, on a weighted-average basis, the assumptions that the Company used to determine the grant-date fair value of stock options granted to employees and directors: Three Months Ended 2021 2020 Risk-free interest rate 1.12 % 1.24 % Expected term (in years) 6.0 6.5 Expected volatility 80.2 % 75.0 % Expected dividend yield 0 % 0 %
Summary of stock option activity	The following table summarizes the Company’s stock option activity: Number of Weighted Weighted Aggregate Outstanding as of March 31, 2021 6,460,184 $ 13.26 7.95 $ 116,193 Granted 1,224,812 $ 32.54 Exercised (163,970) $ 7.16 $ 4,174 Cancelled (109,346) $ 26.98 Outstanding as of June 30, 2021 7,411,680 $ 16.39 7.93 $ 164,305 Options exercisable as of March 31, 2021 2,698,708 $ 8.38 6.79 $ 59,717 Options exercisable as of June 30, 2021 3,340,279 $ 8.97 6.82 $ 98,367
Share-based payment arrangement, restricted stock and restricted stock unit, activity	A summary of the changes in the Company's RSUs during the three months ended June 30, 2021 is as follows: Number of Restricted Shares Weighted Outstanding as of March 31, 2021 15,975 34.15 Granted 657,431 32.84 Vested — — Cancelled (4,298) 31.58 Outstanding as of June 30, 2021 669,108 32.88

Net loss per share (Tables)

Net loss per share (Tables)	3 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Schedule of calculation of basic and diluted net loss per share attributable to common stockholders	Basic and diluted net loss per share attributable to common stockholders was calculated as follows: Three Months Ended June 30, 2021 2020 Numerator: Net loss attributable to common stockholders $ (27,311) $ (17,493) Denominator: Weighted average common shares outstanding, basic and diluted 51,910,331 39,862,319 Net loss per share attributable to common stockholders, basic and diluted $ (0.53) $ (0.44)
Schedule of anti-dilutive securities excluded from the computation of diluted net loss per share attributable to common shareholders	The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: Three Months Ended June 30, 2021 2020 Options to purchase common stock 7,411,680 6,510,522 Warrants to purchase common stock 497,344 497,344 7,909,024 7,007,866

Commitments and contingencies (

Commitments and contingencies (Tables)	3 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Schedule of variable lease components	The table below presents the lease-related assets and liabilities recorded on the consolidated balance sheet as of June 30, 2021: Three Months Ended June 30, 2021 2020 Lease cost Finance lease costs: Amortization of right-to-use asset $ 607 $ 607 Interest on lease liabilities 558 561 Operating lease costs 242 230 Total lease cost $ 1,407 $ 1,398 The following table provides lease disclosure for the three months ended June 30, 2021 and 2020: Three Months Ended June 30, 2021 2020 Other information Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 242 $ 209 Operating cash flows from finance leases $ 558 $ 561 Financing cash flows from finance leases $ 53 $ 32 Right-to-use asset obtained in exchange for new operating lease liabilities $ — $ 1,580 Weighted-average remaining lease term - operating leases 8.6 years 9.8 years Weighted-average remaining lease term - financing leases 18.1 years 19.3 years Weighted-average discount rate - operating leases 9.9 % 10 % Weighted-average discount rate - financing leases 8.3 % 8 %
Summary of the maturity of company's lease liabilities	June 30, 2021 Operating leases Financing lease Total 2022 (remaining three months) $ 731 $ 1,876 $ 2,607 2023 982 2,562 3,544 2024 991 2,639 3,630 2025 1,000 2,718 3,718 2026 1,010 2,799 3,809 Thereafter 4,076 40,905 44,981 Total lease payments 8,790 53,499 62,289 Less: interest 2,837 26,320 29,157 Total lease liabilities $ 5,953 $ 27,179 $ 33,132
Schedule of additional information related to leases	The following table provides lease disclosure as of June 30, 2021 and March 31, 2021:

Geographic information (Tables)

Geographic information (Tables)	3 Months Ended
	Jun. 30, 2021
Segments, Geographical Areas [Abstract]
Summary of company's long-lived assets held in different geographic regions	The Company operates in two geographic regions: the United States (Massachusetts) and the United Kingdom (Oxfordshire). Information about the Company’s long-lived assets held in different geographic regions is presented in the tables below: June 30, 2021 March 31, 2021 United States $ 6,654 $ 6,866 United Kingdom 522 576 $ 7,176 $ 7,442

Nature of the business (Details

Nature of the business (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Net loss	$ (27,311)	$ (17,493)
Accumulated deficit	$ (220,479)		$ (193,168)

Fair value of financial asset_3

Fair value of financial assets and liabilities (Details) - Recurring - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021
Fair value of financial assets and liabilities
Assets fair value	$ 444,811	$ 444,518
Money market funds
Fair value of financial assets and liabilities
Assets fair value	179,008	150,734
US Government Agency bonds
Fair value of financial assets and liabilities
Assets fair value	57,833	67,012
US Treasury bonds
Fair value of financial assets and liabilities
Assets fair value	207,970	226,772
Level 1
Fair value of financial assets and liabilities
Assets fair value	0	0
Level 1 | Money market funds
Fair value of financial assets and liabilities
Assets fair value	0	0
Level 1 | US Government Agency bonds
Fair value of financial assets and liabilities
Assets fair value	0	0
Level 1 | US Treasury bonds
Fair value of financial assets and liabilities
Assets fair value	0	0
Level 2
Fair value of financial assets and liabilities
Assets fair value	444,811	444,518
Level 2 | Money market funds
Fair value of financial assets and liabilities
Assets fair value	179,008	150,734
Level 2 | US Government Agency bonds
Fair value of financial assets and liabilities
Assets fair value	57,833	67,012
Level 2 | US Treasury bonds
Fair value of financial assets and liabilities
Assets fair value	207,970	226,772
Level 3
Fair value of financial assets and liabilities
Assets fair value	0	0
Level 3 | Money market funds
Fair value of financial assets and liabilities
Assets fair value	0	0
Level 3 | US Government Agency bonds
Fair value of financial assets and liabilities
Assets fair value	0	0
Level 3 | US Treasury bonds
Fair value of financial assets and liabilities
Assets fair value	$ 0	$ 0

Short-term investments (Details

Short-term investments (Details) - Short-term investments - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021
Short-term investments
Amortized cost	$ 265,798		$ 293,739
Gross unrealized gains	38		67
Gross unrealized losses	(33)		(22)
Fair value	265,803		293,784
US Government Agency bonds
Short-term investments
Amortized cost	57,841		67,017
Gross unrealized gains	5		12
Gross unrealized losses		$ (13)	(17)
Fair value	57,833		67,012
US Treasury bonds
Short-term investments
Amortized cost	207,957		226,722
Gross unrealized gains	33		55
Gross unrealized losses	(20)		(5)
Fair value	$ 207,970		$ 226,772

Property, plant and equipment_3

Property, plant and equipment, net (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021
Property, plant and equipment, net
Property, plant and equipment , gross	$ 10,342		$ 10,090
Less: Accumulated depreciation and amortization	(3,166)		(2,648)
Property, plant and equipment , net	7,176		7,442
Depreciation and amortization expense	518	$ 391
Office equipment
Property, plant and equipment, net
Property, plant and equipment , gross	833		830
Computer equipment
Property, plant and equipment, net
Property, plant and equipment , gross	1,697		1,695
Plant and laboratory equipment
Property, plant and equipment, net
Property, plant and equipment , gross	6,653		6,369
Leasehold improvements
Property, plant and equipment, net
Property, plant and equipment , gross	785		784
Construction in progress
Property, plant and equipment, net
Property, plant and equipment , gross	$ 374		$ 412

Accrued expenses and other cu_3

Accrued expenses and other current liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021
Accrued Liabilities and Other Liabilities [Abstract]
Accrued research and development costs	$ 4,618	$ 3,862
Accrued compensation and benefits costs	3,325	3,952
Accrued professional fees	445	407
Other	798	514
Total	$ 9,186	$ 8,735

Long-term debt - Hercules Loan

Long-term debt - Hercules Loan Agreement (Details) - USD ($) $ in Thousands	Dec. 15, 2020	Jun. 01, 2020	Aug. 08, 2019	Jun. 30, 2021	Jun. 30, 2020	Oct. 01, 2020	Aug. 31, 2019
Debt Securities [Abstract]
Interest expense				$ 0	$ 284
Non-cash interest expense related to accretion of the debt discount				0	317
Hercules Loan Agreement
Debt Securities [Abstract]
Maximum borrowing capacity		$ 40,000	$ 30,000
Borrowed amount			10,000
Payment of issuance costs			225
Additional closing and legal fees		100	$ 130
Maximum draw per each of three tranches						$ 10,000
Loss on extinguishment of debt	$ 913
Repayments of debt	10,839
Outstanding principal	10,000
Term charge	495
Termination fee due	300
Accrued interest	$ 44
Upfront fees, including closing costs and legal fees		$ 100					$ 355
Interest expense				0	284
Non-cash interest expense related to accretion of the debt discount				0	63
Accretion of the debt discount				0	27
Accretion of the final payment				$ 0	$ 36

Stockholders' equity - Common S

Stockholders' equity - Common Stock and Undesignated Preferred Stock (Details) - $ / shares	Jun. 30, 2021	Mar. 31, 2021
Stockholders' Equity
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Undesignated preferred stock, authorized (in shares)	10,000,000
Preferred stock, Par Value (in dollars per share)	$ 0.001
Undesignated preferred shares issued (in shares)	0
Stock options
Stockholders' Equity
Common stock reserved for issuance (in shares)	14,408,145	14,572,115

Stockholders' equity - ATM Prog

Stockholders' equity - ATM Program (Details) - USD ($)	Aug. 11, 2020	Oct. 31, 2020	Jun. 30, 2020	Nov. 30, 2019	Aug. 31, 2019	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Mar. 31, 2021
Class of Warrant or Right [Line Items]
Common stock, par value (in dollars per share)								$ 0.001	$ 0.001
Net proceeds		$ 269,975,000	$ 107,782,000	$ 85,598,000
Common stock
Class of Warrant or Right [Line Items]
Shares issued during period (in shares)						3,478,261
ATM Program
Class of Warrant or Right [Line Items]
Maximum amount to be sold					$ 75,000,000
Percentage of commission	3.00%
Shares issued during period (in shares)							287,559
Gross proceeds							$ 4,568,000
Offering fees							137,000
Net proceeds							$ 4,431,000
ATM Program | Common stock
Class of Warrant or Right [Line Items]
Common stock, par value (in dollars per share)	$ 0.001
Aggregate offering amount	$ 350,000,000
ATM Program | Maximum | Common stock
Class of Warrant or Right [Line Items]
Aggregate offering amount	$ 62,500,000		$ 30,000,000		$ 75,000,000

Stockholders' equity - Equity o

Stockholders' equity - Equity offerings (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			3 Months Ended
	Oct. 31, 2020	Jun. 30, 2020	Nov. 30, 2019	Jun. 30, 2021	Jun. 30, 2020
Class of Warrant or Right [Line Items]
Net proceeds from issuance after deducting underwriting discounts, commissions and other offering expenses	$ 269,975	$ 107,782	$ 85,598
Underwriting discounts, commissions and other offering expenses	$ 17,525		$ 5,814	$ 0	$ 100
Number of common stocks are exercisable from the November 2019 Pre-Funded Warrants and the June 2020 Pre-Funded Warrants (in shares)				5,284,238
Underwriter rights
Class of Warrant or Right [Line Items]
Number of shares issued (in shares)	5,625,000,000	3,478,261	4,516,561
Share price (in dollars per share)		$ 23	$ 13.61		$ 23
Underwriting discounts, commissions and other offering expenses		$ 7,217
Price per share (in USD per share)	$ 40
Additional Underwriter Options
Class of Warrant or Right [Line Items]
Number of shares issued (in shares)			838,530
Pre-Funded Warrants
Class of Warrant or Right [Line Items]
Number of days to purchase additional shares	30 days	30 days	30 days
Issuance of pre-funded warrants (in shares)	1,562,500,000	1,521,738	2,200,000
Share price (in dollars per share)	$ 39.9999
Pre-funded warrants exercise price (in dollars per share)		$ 22.9999	$ 13.6099		$ 22.9999
Variation between public offering prices of common stock and Pre-Funded Warrants (in dollars per share)	$ 0.0001	$ 0.0001	$ 0.0001
Maximum percentage of holding for exercise warrants (as a percent)	9.99%	9.99%	9.99%
Maximum percentage of increase (decrease) of holding for exercise warrants (as a percent)	19.99%	19.99%
Prior notice period to change percentage of holding (in days)	61 days	61 days
Shares issued during period (in shares)	937,500	652,173

Stock-based compensation - Clas

Stock-based compensation - Classification of expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Share-Based Compensation
Stock-based compensation expense	$ 6,250	$ 2,468
Stock options
Share-Based Compensation
Stock-based compensation expense	5,175	2,468
Restricted stock units
Share-Based Compensation
Stock-based compensation expense	1,075	0
Research and development
Share-Based Compensation
Stock-based compensation expense	2,458	1,000
General and administrative
Share-Based Compensation
Stock-based compensation expense	$ 3,792	$ 1,468

Stock-based compensation - Addi

Stock-based compensation - Additional Information (Details) - shares	May 31, 2021	Apr. 01, 2021	Apr. 01, 2020	Jul. 09, 2018	Apr. 30, 2020	Jun. 30, 2021	Mar. 31, 2021
Stock-Based Compensation
Granted (in shares)	125,000,000					1,224,812
2017 Plan
Stock-Based Compensation
Shares authorized (in shares)						2,659,885
Number of shares available for grant				2,520,247		0
2018 Plan
Stock-Based Compensation
Shares authorized (in shares)				3,617,968
Number of shares available for grant						1,587,935
Share based payment award percentage of outstanding shares				4.00%
Additional shares authorized (in shares)				2,074,028	1,466,749
ESPP
Stock-Based Compensation
Share based payment award percentage of outstanding shares				1.00%
Additional shares authorized (in shares)		518,507	366,687	697,224
Common stock reserved for issuance (in shares)		1,550,375		348,612
Stock options
Stock-Based Compensation
Exercise price for persons holding ten percent of voting power (as a percent)						100.00%
Exercise price for persons holding more than ten percent of voting power (as a percent)						110.00%
Share based payment award expiration period						10 years
Share based payment award vesting period						4 years
Common stock reserved for issuance (in shares)						14,408,145	14,572,115
Stock options | Maximum
Stock-Based Compensation
Expiration period for persons holding ten percent of voting power						5 years
Stock options | Minimum
Stock-Based Compensation
Expiration period for persons holding more than ten percent of voting power						10 years
Restricted stock units
Stock-Based Compensation
Restricted stock unit grant (in shares)						657,431
Restricted stock units | Newly-Hired Executive
Stock-Based Compensation
Restricted stock unit grant (in shares)	88,333,000

Stock-based compensation - Assu

Stock-based compensation - Assumptions to determine grant-date fair value of stock options (Details) - Stock options	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Stock-Based Compensation
Risk-free interest rate	1.12%	1.24%
Expected term (in years)	6 years	6 years 6 months
Expected volatility	80.20%	75.00%
Expected dividend yield	0.00%	0.00%

Stock-based compensation - Stoc

Stock-based compensation - Stock option activity (Details) - USD ($) $ / shares in Units, $ in Thousands	May 31, 2021	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020	Mar. 31, 2021
Number of Shares
Outstanding at beginning of the period (in shares)		6,460,184
Granted (in shares)	125,000,000	1,224,812
Exercised (in shares)		(163,970)
Cancelled (in shares)		(109,346)
Outstanding at end of the period (in shares)		7,411,680
Options exercisable (in shares)		3,340,279			2,698,708
Weighted Average Exercise Price
Outstanding at beginning of the period (in dollars per share)		$ 13.26
Granted (in dollars per share)		32.54
Exercised (in dollars per share)		7.16
Cancelled (in dollars per share)		26.98
Outstanding at end of the period (in dollars per share)		16.39
Options exercisable (in dollars per share)		$ 8.97			$ 8.38
Weighted Average Contractual Term (Years)
Outstanding (years)		7 years 11 months 4 days		7 years 11 months 12 days
Options exercisable (years)		6 years 9 months 25 days		6 years 9 months 14 days
Aggregate Intrinsic Value
Outstanding		$ 164,305			$ 116,193
Exercised		4,174
Options exercisable		$ 98,367			$ 59,717
Stock-Based Compensation
Weighted average grant-date fair value per share of stock options granted		$ 22.29	$ 6.94
Exercised		$ 4,174
Stock options
Stock-Based Compensation
Total unrecognized compensation cost		$ 55,500
Expenses expected to be recognized over a weighted average remaining period		2 years 9 months 25 days

Stock-based compensation - Summ

Stock-based compensation - Summary of RSU Activity (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2021USD ($)$ / sharesshares
Restricted stock units
Number of Restricted Shares
Outstanding as of March 31, 2021 (in shares) | shares	15,975
Granted (in shares) | shares	657,431
Vested (in shares) | shares	0
Cancelled (in shares) | shares	(4,298)
Outstanding as of June 30, 2021 (in shares) | shares	669,108
Weighted Average Grant Date Fair Value
Outstanding as of March 31, 2021 (in dollars per share) | $ / shares	$ 34.15
Granted (in dollars per share) | $ / shares	32.84
Vested (in dollars per share) | $ / shares	0
Cancelled (in dollars per share) | $ / shares	31.58
Outstanding as of June 30, 2021 (in dollars per share) | $ / shares	$ 32.88
Total unrecognized compensation cost | $	$ 20,900
Expenses expected to be recognized over a weighted average remaining period	3 years 10 months 9 days
Stock options
Weighted Average Grant Date Fair Value
Total unrecognized compensation cost | $	$ 55,500
Expenses expected to be recognized over a weighted average remaining period	2 years 9 months 25 days

Net loss per share - Computatio

Net loss per share - Computation of Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Numerator:
Net loss attributable to common stockholders	$ (27,311)	$ (17,493)
Denominator:
Weighted average common shares outstanding, basic (in shares)	51,910,331	39,862,319
Weighted average common shares outstanding, diluted (in shares)	51,910,331	39,862,319
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.53)	$ (0.44)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.53)	$ (0.44)

Net loss per share - Computat_2

Net loss per share - Computation of diluted net loss per share attributable to common stockholders (Details) - shares	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Diluted net loss per share attributable to common stockholders
Antidilutive securities excluded from computation of diluted weighted average shares outstanding	7,909,024	7,007,866
Options to purchase common stock
Diluted net loss per share attributable to common stockholders
Antidilutive securities excluded from computation of diluted weighted average shares outstanding	7,411,680	6,510,522
Warrants to purchase common stock
Diluted net loss per share attributable to common stockholders
Antidilutive securities excluded from computation of diluted weighted average shares outstanding	497,344	497,344

Significant agreements (Details

Significant agreements (Details) $ in Thousands	1 Months Ended
	Jan. 31, 2020patient	Jun. 30, 2021USD ($)	Mar. 31, 2021USD ($)
Significant agreements
Prepaid expenses and other current assets		$ 3,264	$ 4,492
Bristol-Myers Squibb Company
Significant agreements
Number of patients | patient	125
Regeneron Pharmaceuticals, Inc
Significant agreements
Prepaid expenses and other current assets		$ 1,400	$ 1,300

Commitments and contingencies -

Commitments and contingencies - Additional information (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021
Lessee, Lease, Description [Line Items]
Finance lease costs	$ 607	$ 607
Operating lease costs	242	230
Minimum payments committed to manufacturing organization	$ 1,600		$ 1,651
Minimum
Lessee, Lease, Description [Line Items]
Lease term (in years)	8 years
Lease term (in years)	8 years
Maximum
Lessee, Lease, Description [Line Items]
Lease term (in years)	18 years
Lease term (in years)	18 years
Research and development
Lessee, Lease, Description [Line Items]
Finance lease costs	$ 518	517
Interest on lease liabilities	468	471
General and administrative
Lessee, Lease, Description [Line Items]
Operating lease costs	$ 89	$ 89

Commitments and contingencies_2

Commitments and contingencies - Components of lease expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Finance lease costs:
Amortization of right-to-use asset	$ 607	$ 607
Interest on lease liabilities	558	561
Operating lease costs	242	230
Total lease cost	$ 1,407	$ 1,398

Commitments and contingencies_3

Commitments and contingencies - Balance sheet disclosures (Details) $ in Thousands	Jun. 30, 2021USD ($)
Operating leases
2022 (remaining three months)	$ 731
2023	982
2024	991
2025	1,000
2026	1,010
Thereafter	4,076
Total lease payments	8,790
Less: interest	2,837
Total lease liabilities	5,953
Financing lease
2022 (remaining three months)	1,876
2023	2,562
2024	2,639
2025	2,718
2026	2,799
Thereafter	40,905
Total lease payments	53,499
Less: interest	26,320
Total lease liabilities	27,179
Total
2022 (remaining three months)	2,607
2023	3,544
2024	3,630
2025	3,718
2026	3,809
Thereafter	44,981
Total lease payments	62,289
Less: interest	29,157
Total lease liabilities	$ 33,132

Commitments and contingencies_4

Commitments and contingencies - Other information (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021
Leases
Right-to-use operating lease asset	$ 5,653		$ 5,751
Right-to-use finance lease asset	43,915		44,522
Total lease assets	49,568		50,273
Operating lease liabilities, current	975		970
Finance lease liabilities, current	2,506		2,487
Operating lease liabilities, non-current	4,978		5,078
Financing lease liabilities, non-current	24,673		24,745
Total lease liabilities	33,132		$ 33,280
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	242	$ 209
Operating cash flows from finance leases	558	561
Financing cash flows from finance leases	53	32
Right-to-use asset obtained in exchange for new operating lease liabilities	$ 0	$ 1,580
Weighted-average remaining lease term - operating leases	8 years 7 months 6 days	9 years 9 months 18 days
Weighted-average remaining lease term - financing leases	18 years 1 month 6 days	19 years 3 months 18 days
Weighted-average discount rate - operating leases	9.90%	10.00%
Weighted-average discount rate - financing leases	8.30%	8.00%

Geographic information (Details

Geographic information (Details) $ in Thousands	3 Months Ended
	Jun. 30, 2021USD ($)region	Mar. 31, 2021USD ($)
Segments, Geographical Areas [Abstract]
Number of operating geographic regions | region	2
Geographic information
Long-lived assets	$ 7,176	$ 7,442
United States
Geographic information
Long-lived assets	6,654	6,866
United Kingdom
Geographic information
Long-lived assets	$ 522	$ 576