Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Dec. 31, 2019	Feb. 10, 2020
Document And Entity Information
Entity Registrant Name	REPLIMUNE GROUP, INC.
Entity Central Index Key	0001737953
Document Type	10-Q
Document Period End Date	Dec. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--03-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Shell Company	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		36,645,650
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Current assets:
Cash and cash equivalents	$ 63,002	$ 25,704
Short-term investments	117,877	109,107
Research and development incentives receivable	4,775	2,474
Prepaid expenses and other current assets	5,220	3,696
Total current assets	190,874	140,981
Property, plant and equipment, net	5,654	12,159
Restricted cash	1,636	1,186
Right-to-use asset - operating leases	4,731
Right-to-use asset - financing leases	47,528
Total assets	250,423	154,326
Current liabilities:
Accounts payable	6,256	7,084
Accrued expenses and other current liabilities	4,557	2,801
Operating lease liabilities, current	1,011
Financing lease liabilities, current	2,393
Total current liabilities	14,217	9,885
Deferred rent, net of current portion		24
Financing obligation		6,561
Long term debt, net of debt discount	9,739
Operating lease liabilities, non-current	3,886
Finance lease liabilities, non-current	25,016
Total liabilities	52,858	16,470
Commitments and contingencies (Note 12)
Stockholders' Equity:
Common stock, $0.001 par value; 150,000,000 shares authorized as of December 31, 2019 and March 31, 2019; 36,645,650 and 31,656,950 shares issued and outstanding as of December 31, 2019 and March 31, 2019	37	32
Additional paid-in capital	295,084	198,645
Accumulated deficit	(96,509)	(59,766)
Accumulated other comprehensive loss	(1,047)	(1,055)
Total stockholders' equity	197,565	137,856
Total liabilities and stockholders' equity	$ 250,423	$ 154,326

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2019	Mar. 31, 2019
CONDENSED CONSOLIDATED BALANCE SHEETS
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized	150,000,000	150,000,000
Common stock, issued	36,645,650	31,656,950
Common stock, outstanding	36,645,650	31,656,950

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Operating expenses:
Research and development	$ 11,948	$ 7,857	$ 27,573	$ 16,760
General and administrative	4,716	2,280	12,240	6,360
Total operating expenses	16,664	10,137	39,813	23,120
Loss from operations	(16,664)	(10,137)	(39,813)	(23,120)
Other income (expense):
Research and development incentives	951	1,577	2,192	1,937
Investment income	550	882	1,804	1,775
Interest expense	(834)		(1,029)
Change in fair value of warrant liability				(5,452)
Other income (expense)	(192)	5	10	682
Total other income (expense), net	475	2,464	2,977	(1,058)
Net loss attributable to common stockholders	$ (16,189)	$ (7,673)	$ (36,836)	$ (24,178)
Net loss per share attributable to common shareholders, basic and diluted (in dollars per share)	$ (0.46)	$ (0.24)	$ (1.13)	$ (1.18)
Weighted average common shares outstanding-basic and diluted (in shares)	34,877,944	31,577,313	32,742,148	20,433,580

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS
Net loss	$ (16,189)	$ (7,673)	$ (36,836)	$ (24,178)
Other comprehensive income (loss):
Foreign currency translation gain (loss)	408	(102)	8	(1,088)
Net unrealized loss on short-term investments, net of tax	(25)	(55)		(54)
Comprehensive loss	$ (15,806)	$ (7,830)	$ (36,828)	$ (25,320)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEICIT) - USD ($) $ in Thousands	Convertible preferred stock	Common stock ATM sales	Common stock Follow-on public offering	Common stock Initial public offering	Common stock	Additional paid-in capital ATM sales	Additional paid-in capital Follow-on public offering	Additional paid-in capital Initial public offering	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive loss	ATM sales	Follow-on public offering	Initial public offering	Total
Balance at Mar. 31, 2018	$ 86,361				$ 5				$ 1,097	$ (28,932)	$ (238)				$ (28,068)
Balance (in shares) at Mar. 31, 2018	1,925,968				5,007,485
Increase (decrease) in Stockholders' Equity
Foreign currency translation adjustment											(847)				(847)
Unrealized gain (loss) on short-term investments											35				35
Stock-based compensation expense									225						225
Net loss										(10,044)					(10,044)
Balance at Jun. 30, 2018	$ 86,361				$ 5				1,322	(38,976)	(1,050)				(38,699)
Balance (in shares) at Jun. 30, 2018	1,925,968				5,007,485
Balance at Mar. 31, 2018	$ 86,361				$ 5				1,097	(28,932)	(238)				(28,068)
Balance (in shares) at Mar. 31, 2018	1,925,968				5,007,485
Increase (decrease) in Stockholders' Equity
Foreign currency translation adjustment															(1,088)
Unrealized gain (loss) on short-term investments															(54)
Conversion of convertible preferred stock into common stock upon closing of initial public offering															7,094
Conversion of convertible preferred stock warrants into common stock warrants															86,361
Net loss															(24,178)
Balance at Dec. 31, 2018					$ 32				197,697	(53,110)	(1,380)				143,239
Balance (in shares) at Dec. 31, 2018					31,640,672
Balance at Jun. 30, 2018	$ 86,361				$ 5				1,322	(38,976)	(1,050)				(38,699)
Balance (in shares) at Jun. 30, 2018	1,925,968				5,007,485
Increase (decrease) in Stockholders' Equity
Foreign currency translation adjustment											(139)				(139)
Unrealized gain (loss) on short-term investments											(34)				(34)
Exercise of stock options					$ 1				11						12
Exercise of stock options (in shares)					7,149
Conversion of convertible preferred stock into common stock upon closing of initial public offering	$ (86,361)				$ 19				86,342						86,361
Conversion of convertible preferred stock into common stock upon closing of initial public offering (in shares)	(1,925,968)				19,157,360
Conversion of convertible preferred stock warrants into common stock warrants									7,094						7,094
Repurchase of class A common stock upon closing of initial public offering (in shares)					(26,258)
Issuance of common shares upon closing of follow-on public offering, net of issuance costs and underwriter fees				$ 7				$ 101,177						$ 101,184
Issuance of common shares upon closing of follow-on public offering, net of issuance costs and underwriter fees (in shares)				7,407,936
Stock-based compensation expense									718						718
Net loss										(6,461)					(6,461)
Balance at Sep. 30, 2018					$ 32				196,664	(45,437)	(1,223)				150,036
Balance (in shares) at Sep. 30, 2018					31,553,672
Increase (decrease) in Stockholders' Equity
Foreign currency translation adjustment											(102)				(102)
Unrealized gain (loss) on short-term investments											(55)				(55)
Exercise of stock options									153						153
Exercise of stock options (in shares)					87,000
Stock-based compensation expense									880						880
Net loss										(7,673)					(7,673)
Balance at Dec. 31, 2018					$ 32				197,697	(53,110)	(1,380)				143,239
Balance (in shares) at Dec. 31, 2018					31,640,672
Balance at Mar. 31, 2019					$ 32				198,645	(59,766)	(1,055)				137,856
Balance (in shares) at Mar. 31, 2019					31,656,950
Increase (decrease) in Stockholders' Equity
Foreign currency translation adjustment											(182)				(182)
Unrealized gain (loss) on short-term investments											65				65
Exercise of stock options									18						18
Exercise of stock options (in shares)					6,751
Impact of adoption of ASC 842										93					93
Stock-based compensation expense									1,810						1,810
Net loss										(9,508)					(9,508)
Balance at Jun. 30, 2019					$ 32				200,473	(69,181)	(1,172)				130,152
Balance (in shares) at Jun. 30, 2019					31,663,701
Balance at Mar. 31, 2019					$ 32				198,645	(59,766)	(1,055)				137,856
Balance (in shares) at Mar. 31, 2019					31,656,950
Increase (decrease) in Stockholders' Equity
Foreign currency translation adjustment															$ 8
Exercise of stock options (in shares)															184,580
Issuance of common shares upon closing of follow-on public offering, net of issuance costs and underwriter fees (in shares)												287,559
Net loss															$ (36,836)
Balance at Dec. 31, 2019					$ 37				295,084	(96,509)	(1,047)				197,565
Balance (in shares) at Dec. 31, 2019					36,645,650
Balance at Jun. 30, 2019					$ 32				200,473	(69,181)	(1,172)				130,152
Balance (in shares) at Jun. 30, 2019					31,663,701
Increase (decrease) in Stockholders' Equity
Foreign currency translation adjustment											(218)				(218)
Unrealized gain (loss) on short-term investments											(40)				(40)
Exercise of stock options									105						105
Exercise of stock options (in shares)					55,645
Stock-based compensation expense									1,781						1,781
Net loss										(11,139)					(11,139)
Balance at Sep. 30, 2019					$ 32				202,359	(80,320)	(1,430)				120,641
Balance (in shares) at Sep. 30, 2019					31,719,346
Increase (decrease) in Stockholders' Equity
Foreign currency translation adjustment											408				408
Unrealized gain (loss) on short-term investments											(25)				(25)
Exercise of stock options									357						357
Exercise of stock options (in shares)					122,184
Conversion of convertible preferred stock warrants into common stock warrants									28,145						28,145
Issuance of common shares upon closing of follow-on public offering, net of issuance costs and underwriter fees			$ 5			$ 4,431	$ 57,448					$ 4,431	$ 57,453
Issuance of common shares upon closing of follow-on public offering, net of issuance costs and underwriter fees (in shares)		287,559	4,516,561
Stock-based compensation expense									2,344						2,344
Net loss										(16,189)					(16,189)
Balance at Dec. 31, 2019					$ 37				$ 295,084	$ (96,509)	$ (1,047)				$ 197,565
Balance (in shares) at Dec. 31, 2019					36,645,650

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss		$ (36,836)	$ (24,178)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	$ 2,344	5,935	1,823
Depreciation and amortization	107	191	106
Change in fair value of warrant liability			5,452
Net amortization of premiums and discounts on short-term investments		(899)	(1,171)
Noncash interest expense		94	40
Changes in operating assets and liabilities:
Research and development incentives receivable		(2,184)	340
Prepaid expenses and other current assets		(1,520)	(589)
Operating lease, right-of-use-asset		421
Finance lease, right-of-use-asset		666
Long term prepaid rent		(14,051)
Accounts payable		(2,585)	(521)
Accrued expenses and other current liabilities		1,781	(767)
Operating lease liabilities		(303)
Deferred rent			120
Net cash used in operating activities		(49,290)	(19,345)
Cash flows from investing activities:
Purchases of property, plant and equipment		(5,202)	(752)
Purchase of short-term investments		(119,611)	(134,624)
Proceed from sales and maturities of short-term investments		111,739	58,958
Net cash provided by (used in) investing activities		(13,074)	(76,418)
Cash flows from financing activities:
Proceeds from issuance of common stock in follow-on public offering, net of underwriting fees and discounts		57,453
Proceeds from issuance of prefunded warrants to purchase common stock, net of underwriting fees and discounts		28,145
Proceeds from issuance of common stock through ATM sales		4,431
Proceeds from long-term debt		10,000
Payment of issuance costs		(355)	(2,157)
Exercise of stock options		480	165
Proceeds from issuance of common stock in initial public offering, net of underwriting fees and discounts			103,341
Principal payment of finance lease obligation	(22)	(22)
Net cash provided by financing activities		100,132	101,349
Effect of exchange rate changes on cash, cash equivalents and restricted cash		(20)	(1,009)
Net increase in cash, cash equivalents and restricted cash		37,748	4,577
Cash, cash equivalents and restricted cash at beginning of period		26,890	17,661
Cash, cash equivalents and restricted cash at end of period	64,638	64,638	22,238
Supplemental Cash Flow Information [Abstract]
Interest Paid, Excluding Capitalized Interest, Operating Activities		282
Supplemental disclosure of non-cash investing and financing activities:
Conversion of convertible preferred stock warrants into common stock warrants			7,094
Conversion of convertible preferred stock into common stock	28,145		86,361
Purchases of property and equipment included in accounts payable			108
Lease assets obtained in exchange for new financing lease liabilities	48,224	48,224
Lease assets obtained in exchange for new operating lease liabilities	$ 5,152	$ 5,152
Amounts capitalized under build-to-suit lease transaction			$ 4,932

Nature of the business	9 Months Ended
Nature of the business	Dec. 31, 2019
Nature of the business
Nature of the business	1. 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 Limited (“Replimune UK”) was incorporated in 2015 under the laws of England, and was the sole shareholder of Replimune, Inc. (“Replimune US”), a Delaware corporation. On July 5, 2017, Replimune Group, Inc., a Delaware corporation, was incorporated and on July 10, 2017 the shareholders of Replimune UK effected a share‑for‑share exchange pursuant to which they exchanged their outstanding shares in Replimune UK for shares in Replimune Group, Inc., on a one‑for‑one basis. In addition, the holders of warrants and stock options to purchase Replimune UK capital stock canceled their warrants to purchase shares of series seed convertible preferred stock and stock options in Replimune UK and were issued replacement warrants to purchase shares of series seed convertible preferred stock and stock options to acquire Replimune Group, Inc. capital stock on a one‑for‑one basis. These transactions are collectively referred to as the reorganization. Upon completion of the reorganization, the historical consolidated financial statements of Replimune UK became the historical consolidated financial statements of Replimune Group, Inc. because the reorganization was accounted for similar to a reorganization of entities under common control due to the high degree of common ownership of Replimune UK and Replimune Group, Inc. and lack of economic substance to the transaction. The Company concluded that the reorganization resulted in no change in the material rights and preferences of each respective class of equity interests and no change in the fair value of each respective class of equity interests before and after the reorganization. On December 8, 2017, Replimune UK transferred all outstanding shares of its wholly owned subsidiary, Replimune US to Replimune Group, Inc. Replimune Group. Inc., a Delaware corporation, is the sole shareholder of Replimune UK, Replimune US and Replimune Securities Corporation, a Massachusetts corporation that was incorporated in November 2017. 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. Forward stock split On July 9, 2018, the Company effected a l -for-9.94688 forward stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for each series of the Company’s Convertible Preferred Stock (see Note 8). Accordingly, all share and per share amounts for all periods presented in the accompanying consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this forward stock split and adjustment of the convertible preferred stock conversion ratios. Further, on July 9, 2018, the Company’s authorized shares of common stock were increased to 27,314,288. Accordingly, the authorized shares of common stock presented in the accompanying consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect the newly authorized shares of common stock. Initial public offering On July 24, 2018, the Company completed an initial public offering (“IPO”) of its common stock and issued and sold 6,700,000 shares of common stock at a public offering price of $15.00 per share, resulting in net proceeds of $93,465 after deducting underwriting discounts and commissions but before deducting offering costs of $2,157. Upon closing of the IPO, the Company’s outstanding convertible preferred stock automatically converted into shares of common stock (see Note 8). Upon conversion of the convertible preferred stock, the Company reclassified the carrying value of the convertible preferred stock to common stock and additional paid-in capital. The warrant to purchase shares of the Company’s series seed convertible preferred stock was converted into a warrant to purchase shares of the Company’s common stock upon the closing of the IPO. As a result, the warrant liability was remeasured a final time on the closing date of the IPO and reclassified to stockholders’ equity. Additionally, the Company repurchased 26,258 shares of class A common stock at a price equal to its par value upon the closing of the IPO. On July 30, 2018, the Company issued and sold an additional 707,936 shares of its common stock at the IPO price of $15.00 per share pursuant to the underwriters’ partial exercise of their option to purchase additional shares of common stock, resulting in additional net proceeds of $9,876 after deducting discounts and commissions and other offering expenses. Also, in connection with the completion of its IPO on July 24, 2018, the Company filed an amended and restated certificate of incorporation with the Secretary of State of the State of Delaware to authorize the issuance of up to 150,000,000 shares of common stock, par value $0.001 per share, and 10,000,000 shares of undesignated preferred stock, par value $0.001 per share. 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 $16,189 and $7,673 for the three months ended December 31, 2019 and 2018, respectively and net losses of $36,836 and $24,178 for the nine months ended December 31, 2019 and 2018, respectively. In addition, as of December 31, 2019, the Company had an accumulated deficit of $96,509. The Company expects to continue to generate operating losses for the foreseeable future. As of February 13, 2020, 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 condensed consolidated financial statements. The future viability of the Company beyond that point is dependent on its ability to raise additional capital to finance its operations. If the Company is unable to obtain funding it could be forced to delay, reduce or eliminate some or all of its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects, or it may be unable to continue operations. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all.

Summary of significant accounting policies

9 Months Ended

Dec. 31, 2019

Summary of significant accounting policies

Summary of significant accounting policies

2. Summary of significant accounting policies

Principles 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 wholly owned subsidiaries, Replimune UK, Replimune US and Replimune Securities Corporation, after elimination of all intercompany accounts and transactions. The consolidated financial statements reflect the capital as if Replimune Group, Inc. had been in existence for all periods presented.

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 common stock and 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. 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 December 31, 2019, the consolidated statements of operations, of comprehensive loss and of convertible preferred stock and stockholders’ equity for the three and nine months ended December 31, 2019 and 2018 and the consolidated statements of cash flows for the nine months ended December 31, 2019 and 2018 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 December 31, 2019 and the results of its operations for the three and nine months ended December 31, 2019 and 2018. The financial data and other information disclosed in these consolidated notes related to the three and nine months ended December 31, 2019 and 2018 are unaudited. The results for the three and nine months ended December 31, 2019 are not necessarily indicative of results to be expected for the year ending March 31, 2020, 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, 2019.

During the three and nine months ended December 31, 2019, 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, 2019, except as described below.

Debt Issuance Costs

Debt issuance costs consist of payments made to secure commitments under certain debt financing arrangements. These amounts are recognized as interest expense over the period of the financing arrangement using the effective interest method. If the financing arrangement is canceled or forfeited, or if the utility of the arrangement to the Company is otherwise compromised, these costs are recognized as interest expense immediately. The Company's condensed consolidated financial statements present debt issuance costs related to a recognized debt liability as a direct reduction from the carrying amount of that debt liability.

Recently Adopted Accounting Pronouncements

In June 2018, the FASB issued Accounting Standards Updates (“ASU” ) No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”). ASU 2018-17 expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. ASU 2018-17 also clarifies that Topic 718 does not apply to share-based payments used to effectively provide (1) financing to the issuer or (2) awards granted in conjunction with selling goods or services to customers as part of a contract accounted for under Revenue from Contracts with Customers (Topic 606). The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. Early adoption is permitted. The Company adopted ASU 2018-17 on April 1, 2019. The adoption of ASU 2018-17 did not have a material impact on the Company’s consolidated financial statements.

In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815) I. Accounting for Certain Financial Instruments with Down Round Features II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (“ASU 2017-11”). Part I applies to entities that issue financial instruments such as warrants, convertible debt or convertible preferred stock that contain down-round features. Part II replaces the indefinite deferral for certain mandatorily redeemable noncontrolling interests and mandatorily redeemable financial instruments of nonpublic entities contained within Accounting Standards Codification (“ASC”) Topic 480 with a scope exception and does not impact the accounting for these mandatorily redeemable instruments. ASU 2017-11 is required to be adopted for annual periods beginning after December 15, 2018, including interim periods within those fiscal years. The Company adopted ASU 2017-11 on April 1, 2019. The adoption of ASU 2017-11 did not have a material impact on the Company’s consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02 ("ASU 2016-02"), Leases (Topic 842), which supersedes FASB Topic 840, Leases (Topic 840) and provides principles for the recognition, measurement, presentation and disclosure of leases for both lessees and lessors. The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of classification. Leases with a term of 12 months or less will be accounted for similar to existing guidance for operating leases. In January 2018, the FASB issued ASU 2018-01, Leases (Topic 842) Land Easement Practical Expedient for Transition to Topic 842, which amends ASU 2016-02 to provide entities an optional transition practical expedient to not evaluate under Topic 842 existing or expired land easements that were not previously accounted for as leases under the current leases guidance in Topic 842. An entity that elects this practical expedient should evaluate new or modified land easements under Topic 842 beginning at the date that the entity adopts Topic 842. In July 2018, the FASB also issued ASU 2018-11, Leases (Topic 842): Targeted Improvements, which provides an optional transition method that allows entities to elect to apply the standard prospectively at its effective date, versus recasting the prior periods presented.

The Company adopted ASU 2016-02, as amended, on April 1, 2019, which supersedes the current leasing guidance and upon adoption, requires lessees to recognize right-of-use assets and lease liabilities on the balance sheet for all leases with terms longer than 12 months. Leases are classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. Upon the adoption of the guidance, operating leases are capitalized on the balance sheet at the present value of lease payments. The balance sheet amount recorded for existing leases at the date of adoption of ASU 2016-02 was calculated using the applicable incremental borrowing rate at the date of adoption.

The Company adopted ASU 2016-02, including several practical expedients on April 1, 2019. The Company elected the available package of practical expedients, which allows the Company to not reassess previous accounting conclusions around whether arrangements are or contain leases, the classification of leases, and the treatment of initial direct costs. The Company also made an accounting policy election to utilize the short-term lease exemption, whereby leases with a term of 12 months or less will not follow the recognition and measurement requirements of the new standard. Upon adoption, the Company recognized total right-of-use assets of $789, with corresponding liabilities of $837 on the consolidated balance sheets. Additionally, the Company derecognized $11,514 of construction in progress assets and $6,561 of financing obligations and recorded long term prepaid rent of $5,006 on the consolidated balance sheet (see Note 12).

The following table summarizes the financial impact on the Company’s condensed consolidated balance sheet upon the adoption of ASU 2016-02 and the cumulative effect adjustment on April 1, 2019:


	March 31, 2019		Adjustments		April 1, 2019
Property, plant, and equipment, net	$	12,159	$	(11,514)	$	645
Right-to-use asset	$	—	$	789	$	789
Long term prepaid rent	$	—	$	5,006	$	5,006
Lease liabilities, current	$	—	$	388	$	388
Lease liabilities, non-current	$	—	$	449	$	449
Accrued expenses	$	2,801	$	(24)	$	2,777
Deferred rent, net of current portion	$	24	$	(24)	$	—
Financing obligation	$	6,561	$	(6,561)	$	—
Accumulated deficit	$	(59,766)	$	93	$	(59,673)

Recently Issued Accounting Pronouncements

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820), Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”). The amendments in this ASU require certain existing disclosure requirements in Topic 820 to be modified or removed, and certain new disclosure requirements to be added to the Topic. In addition, this ASU allows entities to exercise more discretion when considering fair value measurement disclosures. ASU 2018-13 will be effective for the Company beginning April 1, 2020 with early adoption permitted. The Company is in the process of evaluating the impact of ASU 2018-13 on its consolidated financial statements and disclosures.

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, 2019. Early adoption is permitted for all periods beginning after December 15, 2018. The Company is currently in the process of evaluating the impact the standard will have on its consolidated financial statements.

Fair value of financial assets and liabilities

9 Months Ended

Dec. 31, 2019

Fair value of financial assets and liabilities

Fair value of financial assets and liabilities

3. 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
	December 31, 2019 Using:
	Level 1		Level 2		Level 3		Total
Assets
Money market funds	$	—	$	35,853	$	—	$	35,853
Commercial paper		—		42,172		—		42,172
US Government Agency bonds		—		23,158		—		23,158
US Treasury bonds		—		28,105		—		28,105
Corporate debt securities		—		34,564		—		34,564
	$	—	$	163,852	$	—	$	163,852


	Fair Value Measurements as of
	March 31, 2019 Using:
	Level 1		Level 2		Level 3		Total
Assets
Money market funds	$	—	$	2,676	$	—	$	2,676
Commercial paper		—		46,687		—		46,687
US Government Agency bonds		—		20,884		—		20,884
US Treasury bonds		—		41,057		—		41,057
Corporate debt securities		—		8,467		—		8,467
	$	—	$	119,771	$	—	$	119,771

During the three and nine months ended December 31, 2019 and 2018, there were no transfers between levels.

Valuation of cash equivalents and short‑term investments

Money market funds, commercial paper, US Government Agency bonds, US Treasury bonds and corporate debt securities 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.

Valuation of Warrant Liability

The warrant liability is related to the warrants to purchase shares of series seed convertible preferred stock (see Note 8). The fair value of the warrant liability was determined based on significant inputs not observable in the market , which represents a Level 3 measurement within the fair value hierarchy. Upon the closing of the IPO in July 2018, the warrant to purchase shares of the Company’s series seed convertible preferred stock was converted into a warrant to purchase shares of the Company’s common stock. As a result, the warrant liability was remeasured a final time on the closing date of the IPO and reclassified to stockholders’ equity.

The Company used the Black-Scholes option-pricing model, which incorporated assumptions and estimates, to value the warrant liability. Key estimates and assumptions impacting the fair value measurement include: (i) the expected term of the warrants, (ii) the risk-free interest rate, (iii) the expected dividend yield, (iv) expected volatility of the price of the underlying series seed convertible preferred stock and (v) the fair value of the series seed convertible preferred stock on the valuation date. The Company estimated the fair value per share of the underlying series seed convertible preferred stock based, in part, on the results of third-party valuations and additional factors deemed relevant. The risk-free interest rate was determined by reference to the U.S. Treasury yield curve for time periods approximately equal to the remaining contractual term of the warrants. The Company estimated a 0% expected dividend yield based on the fact that the Company has never paid or declared dividends and does not intend to do so in the foreseeable future. Prior to July 2018, the Company was a private company and accordingly, lacked company-specific historical and implied volatility information of its stock, the expected stock volatility was based on the historical volatility of publicly traded peer companies for a term equal to the remaining expected term of the warrants.

Based on the terms and conditions of the warrant, upon closing of the Company’s IPO in July 2018, the warrant to purchase shares of the Company’s series seed convertible preferred stock was converted into a warrant to purchase shares of the Company’s common stock. On that date, the Company remeasured the warrant liability to fair value and reclassified the total carrying value to additional paid-in capital. The Company performed the final remeasurement of the warrant liability using the IPO price of $15.00 per share and recorded the change in fair value as a component of total other income (expense), net in the consolidated statement of operations.

The following assumptions were used to measure the fair market value of the warrant liability upon the conversion date:


	Nine Months
	Ended
	December 31,
	2018
Risk-free interest rate		2.81	%
Expected dividend yield		0	%
Expected term (in years)		7.2
Expected volatility		64.4	%
Fair value of series seed preferred stock	$	15.00

The following table presents a roll forward of the warrant liability:


	Warrant
	Liability
Balance at March 31, 2018	$	1,642
Change in fair value		5,452
Conversion of convertible preferred stock warrant into common stock warrant		(7,094)
Balance at December 31, 2018	$	—

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Short-term investments

9 Months Ended

Dec. 31, 2019

Short-term investments

Short-term investments

4. Short‑term investments

Short‑term investments by investment type consisted of the following:


	December 31, 2019
			Gross unrealized		Gross unrealized
	Amortized cost		gains		losses		Fair value
Commercial paper	$	42,148	$	24	$	—	$	42,172
US Government agency bonds		13,045		—		(9)		13,036
US Treasury bonds		28,107		—		(2)		28,105
Corporate debt securities		34,562		5		(3)		34,564
	$	117,862	$	29	$	(14)	$	117,877


	March 31, 2019
			Gross unrealized		Gross unrealized
	Amortized cost		gains		losses		Fair value
Commercial paper	$	46,687	$	2	$	(2)	$	46,687
US Government agency bonds		15,889		4		—		15,893
US Treasury bonds		38,047		13		—		38,060
Corporate debt securities		8,469		—		(2)		8,467
	$	109,092	$	19	$	(4)	$	109,107

Property, plant and equipment, net

9 Months Ended

Dec. 31, 2019

Property, plant and equipment, net

Property, plant and equipment, net

5. Property, plant and equipment, net


	December 31,		March 31,
	2019		2019
Construction in progress	$	726	$	124
Plant and laboratory equipment		3,453		584
Leasehold improvements		368		154
Computer equipment		981		138
Office equipment		721		49
Build-to-suit lease asset		—		11,514
		6,249		12,563
Less: Accumulated depreciation and amortization		(595)		(404)
	$	5,654	$	12,159

Depreciation and amortization expense was $107 and $191 for the three and nine months ended December 31, 2019, respectively, and $37 and $106 for the three and nine months ended December 31, 2018, respectively.

Build-to-suit lease asset, as of March 31, 2019, included $11,514 capitalized in connection with the Company's build-to-suit lease accounting. Upon transition to ASC 842, the Company determined that it did not control the build-to-suit lease asset and the arrangement has been accounted for under ASC 842 guidance. Upon the adoption of ASC 842, the Company derecognized $11,514 of construction in progress and $6,561 of financing obligations and recorded long term prepaid rent of $5,006 on the consolidated balance sheet (see Note 12).

Accrued expenses and other current liabilities

9 Months Ended

Dec. 31, 2019

Accrued expenses and other current liabilities.

Accrued expenses and other current liabilities

6. Accrued expenses and other current liabilities

Accrued expenses and other current liabilities consisted of the following:


	December 31,		March 31,
	2019		2019
Accrued research and development costs	$	1,416	$	530
Accrued compensation and benefits costs		2,099		1,510
Accrued professional fees		697		464
Deferred rent		—		24
Other		345		273
	$	4,557	$	2,801

Long-Term Debt

9 Months Ended

Dec. 31, 2019

Long-Term Debt

Long-Term Debt

7. Long-Term Debt

Long-term debt consisted of the following:


	December 31,
	2019
Principal amount of long-term debt	$	10,000
Unamortized debt discount		(261)
Long-term debt, net of discount	$	9,739

Hercules Loan Agreement

On August 8, 2019, (the “Closing Date”) the Company and certain of its affiliates entered into a Loan and Security Agreement (the “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 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. The Company may borrow the unused $20,000 available under the Term Loan Facility in two separate advances. The second advance of up to $10,000 may be borrowed between January 1, 2020 and December 15, 2020 and the third advance of up to $10,000 may be borrowed between July 1, 2020 and June 30, 2021.

Advances under the Term Loan Facility bear interest at a rate per annum equal to the greater of either (i) the prime rate as reported in The Wall Street Journal plus 2.75%, or (ii) 8.75%. The Loan Agreement includes covenants, limitations, and events of default customary for similar facilities. The term of the Loan Agreement is four years, ending August 1, 2023.

Interest is payable on a monthly basis until March 1, 2022 (the “Amortization Date”). After the Amortization Date, payments shall consist of equal monthly installments of principal and interest payable until the secured obligations are repaid in full.

At any time the Company may prepay the principal of any advance pursuant to the terms of the Term Loan Facility subject to a prepayment charge equal to: 3.0%, if such advance is prepaid within the first twelve months following the Closing Date, 2.0%, if such advance is prepaid after twelve months but prior to twenty four months following the Closing Date, and 1.0%, if such advance is prepaid anytime thereafter. The Company will also pay a charge equal to the product of 4.95% and the aggregate amount of any advance made pursuant to the terms of the Term Loan Facility.

The Term Loan Facility is secured by substantially all of the Company’s assets, but excluding its intellectual property, and subject to certain exceptions and exclusions.

The Loan Agreement contains customary covenants for transactions of this type and other covenants agreed to by the parties, including, among others, (i) the provision of delivery of annual and quarterly financial statements and insurance policies and restrictions on incurring debt, granting liens, making acquisitions, making loans, paying dividends, dissolving, and entering into leases and asset sales. The Loan Agreement also provides for customary events of default, including, among others, events of default relating to failure to make payment, bankruptcy, breach of covenants, breaches of representations and warranties, change of control, judgment and material adverse effects.

In connection with entering into the Hercules Loan Agreement the Company also 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. The debt discount is reflected as a reduction of the carrying value of long-term debt on the Company’s condensed consolidated balance sheet and is being amortized to interest expense over the term of the loan using the effective interest method.

The Company recognized aggregate interest expense under the Hercules Loan Agreement of $302 and $376 during the three and nine months ended December 31, 2019, which included non-cash interest expense of $81 and $94 related to the accretion of the debt discount and the final payment. As of December 31, 2019, the unamortized debt discount was $261. The Company’s annual effective interest rate of the Hercules Loan Agreement was approximately 10.1% for the period from August 8, 2019 to December 31, 2019.

There were no principal payments due or paid under the Hercules Loan Agreement during the three and nine months ended December 31, 2019.

Future payments of long-term debt, as of December 31, 2019 are as follows (fiscal years):


2021	$	—
2022		527
2023		6,558
2024		2,915
Total debt payments	$	10,000

The table of future payments of long-term debt excludes the end of term charge of $495 which is due upon the maturity of the loan.

Stockholders' Equity	9 Months Ended
Stockholders' Equity	Dec. 31, 2019
Stockholders' Equity
Stockholders' Equity	8. Stockholders’ Equity Common Stock As of December 31, 2019 and March 31, 2019, 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 December 31, 2019 and March 31, 2019, the Company had reserved 10,472,126 and 6,873,744 shares of common stock for the exercise of outstanding stock options, 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, respectively. Undesignated Preferred Stock As of December 31, 2019 and March 31, 2019, 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 December 31, 2019 or March 31, 2019. Convertible Preferred Stock The Company has issued series seed convertible preferred stock (the “series seed preferred stock”), series A convertible preferred stock (the “series A preferred stock”) and series B convertible preferred stock (the “series B preferred stock”). The series seed preferred stock, series A preferred stock and series B preferred stock are collectively referred to as the “preferred stock.” In connection with the closing of the IPO, the preferred stock converted into 19,157,360 shares of common stock on a 1:9.94688 basis. There was no preferred stock outstanding as of December 31, 2019. Preferred Stock Warrants In connection with the issuance of the series seed preferred stock, the Company issued to the holders of the series seed preferred stock warrants for the purchase of 50,000 shares of series seed preferred stock, which became fully vested and exercisable in the year of issuance. The warrants to purchase shares of series seed preferred stock were issued at an exercise price of $10.00 per share and expire on the earlier of September 16, 2025 or a qualified change of control event. The issuance date fair value of the warrants to purchase shares of series seed preferred stock was $391 and was recorded as a liability with a corresponding reduction in the carrying value of the series seed preferred stock. The Company did not recognize any losses for the change in fair value of warrant liability within total other income (expense), net in the consolidated statements of operations for the three and nine months ended December 31, 2019, related to the change in fair value of the warrant liability. The Company recognized a loss of $0 and $(5,452) in change in fair value of warrant liability within total other income (expense), net in the consolidated statements of operations for the three and nine months ended December 31,2018, respectively, related to the change in fair value of the warrant liability. Upon the closing of the Company’s IPO in July 2018, all outstanding convertible preferred stock was converted into common stock and the series seed preferred stock warrants became exercisable for 497,344 shares of common stock instead of series seed preferred stock. As a result, the warrant liability was remeasured a final time on the closing date of the IPO and reclassified to stockholders’ equity. ATM Program In August 2019, the Company entered into a Sales Agreement (the “Sales Agreement”) with SVB Leerink LLC (the “Agent”), pursuant to which the Company may 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 (the “Shares”) , through the Agent, as the Company’s sales agent. Any Shares to be offered and sold under the 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 8, 2019 for an offering of up to $250,000 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 Sales Agreement, the Agent will use commercially 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 will pay the Agent a commission of 3.0% of the gross proceeds from the sale of the Shares, if any. During the nine months ended December 31, 2019, the Company has issued and sold 287,559 shares of common stock for gross proceeds of $4,568 less offering fees of $137 for net proceeds of $4,431 under the ATM program. Equity offerings In November 2019, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with J.P. Morgan Securities LLC and SVB Leerink LLC, as representatives of the several underwriters named therein (the “Underwriters”), relating to the issuance and sale of an aggregate of (a) 3,678,031 shares of the Company’s common stock (the “Shares”), and (b) pre-funded warrants to purchase 2,200,000 shares of the Company’s common stock (the “Pre-Funded Warrants”) to the Underwriters (the “Offering”). The Shares were sold to the purchasers at the public offering price of $13.61 per share. The Pre-Funded Warrants were sold at a public offering price of $13.6099 per Pre-Funded Warrant, which represents the per share public offering price for the Company’s common stock less a $0.0001 per share exercise price for each such Pre-Funded Warrant. Pursuant to the Underwriting Agreement, the Company also granted the Underwriters a 30-day option to purchase up to 881,704 additional shares of its common stock. In December 2019, the Underwriters partially exercised their purchase option and the Company issued and sold an additional 838,530 shares of its common stock. The Company received aggregate net proceeds of approximately $85,598 after deducting underwriting discounts, commissions and other offering expenses payable by the Company of approximately $5,814. The Pre-Funded Warrants are exercisable at any time after the date of issuance. A holder of Pre-Funded Warrants may not exercise the 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. A holder of Pre-Funded Warrants may increase or decrease this percentage by providing at least 61 days’ prior notice to the Company. As of December 31, 2019, none of the warrants had been exercised.

Stock-Based Compensation

9 Months Ended

Dec. 31, 2019

Stock-Based Compensation

Stock-Based Compensation

9. Stock‑Based Compensation

2015 Enterprise Management 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 as of December 31, 2019, of which 0 remained available for future grants as of December 31, 2019. 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 2018 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 IPO. 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, which is equal to the sum of (i) 3,486,118 shares of the Company’s common stock, plus (ii) the number of shares of the Company’s common stock reserved for issuance under the 2017 Plan that remain available as of the effective date of the 2018 Plan (not to exceed 131,850 shares of the Company’s common stock). 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. On April 1, 2019, the number of shares reserved for issuance under the 2018 Plan automatically increased by 1,266,370 shares pursuant to the terms of the 2018 Plan. As of December 31, 2019, 2,193,176 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.

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 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, on April 1, 2019, the number of shares reserved for issuance under the ESPP automatically increased by 316,592 shares, for a total of 665,204 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.

Stock option valuation

The fair value of stock option grants is estimated using the Black-Scholes option-pricing model. The Company lacks company- specific historical and implied volatility information. Therefore, it estimated its expected stock volatility based on the historical volatility of a publicly traded set of 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				Nine Months Ended
	December 31,				December 31,
	2019		2018		2019		2018
Risk-free interest rate	1.68	%	2.83	%	2.17	%	2.83	%
Expected term (in years)	6.1		6.1		6.0		6.1
Expected volatility	69.7	%	63.3	%	71.0	%	61.7	%
Expected dividend yield	0	%	0	%	0	%	0	%

Stock options

The following table summarizes the Company’s stock option activity:


		Weighted		Weighted
		Average		Average	Aggregate
	Number of	Exercise		Contractual	Intrinsic
	Shares	Price		Term (Years)	Value
Outstanding as of March 31, 2019	3,721,784	$	7.14	8.61	$	30,150
Granted	1,515,535		15.00	9.41
Exercised	(184,580)		2.60
Cancelled	(136,337)		11.26
Outstanding as of December 31, 2019	4,916,402	$	9.46	8.20	$	26,959
Options exercisable as of March 31, 2019	1,278,930	$	2.51	7.75	$	16,249
Options exercisable as of December 31, 2019	1,924,564	$	5.33	7.40	$	17,650

The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock.

The total fair value of options vested during the three and nine months ended December 31, 2019 was $1,063 and $4,480, respectively. The total fair value of options vested during the three and nine months ended December 31, 2018 was $211 and $1,042, respectively. As of December 31, 2019, there were no outstanding unvested service‑based stock options held by non‑employees.

Stock‑Based Compensation

Stock‑based compensation expense was classified in the consolidated statements of operations as follows:


	Three Months Ended				Nine Months Ended
	December 31,				December 31,
	2019		2018		2019		2018
Research and development	$	1,318	$	473	$	2,974	$	989
General and administrative		1,026		407		2,961		834
	$	2,344	$	880	$	5,935	$	1,823

As of December 31, 2019, total unrecognized compensation cost related to the unvested stock‑based awards was $18,483, which is expected to be recognized over a weighted average period of 2.70 years.

Net loss per share

9 Months Ended

Dec. 31, 2019

Net loss per share

Net loss per share

10. Net loss per share

Basic and diluted net loss per share attributable to common stockholders was calculated as follows:


	Three Months Ended				Nine Months Ended
	December 31,				December 31,
	2019		2018		2019		2018
Numerator:
Net loss attributable to common stockholders	$	(16,189)	$	(7,673)	$	(36,836)	$	(24,178)
Denominator:
Weighted average common shares outstanding, basic and diluted		34,877,944		31,577,313		32,742,148		20,433,580
Net loss per share attributable to common stockholders, basic and diluted	$	(0.46)	$	(0.24)	$	(1.13)	$	(1.18)

Included within weighted average common shares outstanding are common shares issuable upon the exercise of the pre-funded warrants as the warrants are exercisable at any time for nominal consideration, and as such, the shares are considered outstanding for the purpose of calculating 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. Common A stock has been excluded from the computation of diluted net loss per share because the shares have nominal economic participation rights. 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 and Nine Months Ended
	December 31,
	2019	2018
Options to purchase common stock	4,916,402	3,673,535
Warrants to purchase convertible preferred stock (as converted to common stock)	497,344	497,344
	5,413,746	4,170,879

Significant agreements	9 Months Ended
Significant agreements	Dec. 31, 2019
Significant agreements
Significant agreements	11. 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, nivolumab for use in the Company’s ongoing clinical trial of RP1 in combination with nivolumab. 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 manufacture and supply its compound, at its cost and for no charge 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-PD1 refractory melanoma. Unless earlier terminated, the agreement will remain in effect until the latter of (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 (x) in the event of an uncured material breach by the other party, (y) in the event the other party is insolvent or in bankruptcy proceedings or (z) for safety reasons. Upon termination, the licenses granted to the Company to use BMS’s compound in the clinical trial will terminate. As of December 31, 2019, the Company had not incurred any costs and does not expect to incur future costs in connection with this agreement. 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. 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, (ii) 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 (iii) in the event of a material breach. 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 and nine months ended December 31, 2019 and 2018, the Company did not make any payments under the terms of the agreement to Regeneron. During the three and nine months ended December 31, 2019, the Company received payments under the terms of the agreement to Regeneron of $760 and $2,008, respectively, which were recorded as an offset to research and development expenses on the consolidated statement of operations. The Company did not receive any payments under the terms of the agreement to Regeneron during the three and nine months ended December 31, 2018. As of December 31, 2019 and March 31, 2019, the Company recorded $1,017 and $337 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

9 Months Ended

Dec. 31, 2019

Commitments and contingencies

Commitments and contingencies

12. Commitments and contingencies

Leases

In December 2015, the Company entered into a lease agreement for office space in Woburn, Massachusetts, which expires on March 30, 2021. The Company has the option to extend the lease agreement for successive periods of five years. Monthly lease payments, inclusive of base rent and ancillary charges, total $7. Monthly base rent is subject to increase each year in proportion to the Consumer Price Index.

In April 2016, the Company entered into a lease agreement for office and laboratory space in Abingdon, England, which expires on April 3, 2026. The Company has the right to terminate the lease as of April 4, 2021 upon at least nine months’ prior written notice. Monthly lease payments are inclusive of base rent, ancillary charges, non‑rent shared tenant occupancy costs and the respective value added tax to be paid. Monthly lease payments include base rent of approximately $23 through December 3, 2016 and $31 thereafter. Monthly base rent is subject to increase after April 2021 in proportion to the Retail Price Index.

In June 2018, the Company entered into an agreement to lease approximately 63,000 square feet of office, manufacturing and laboratory space within a previously occupied building with approximately 106,000 square feet of rentable space in Framingham, Massachusetts. Pursuant to the lease agreement, the lease term commenced in December 2018, subject to the landlord completing certain agreed upon landlord improvements. The rent commenced in August 2019. The initial lease term is ten years from the rent commencement date and includes two optional five-year extensions. Annual lease payments during the first year are $2,373 with increases of 3.0% each year.

Upon transition to ASC 842, the Company determined that it did not control the build-to-suit lease asset and the arrangement has been accounted for under ASC 842 guidance. Upon the adoption of ASC 842, the Company derecognized $11,514 of construction in progress and $6,561 of financing obligations and recorded long term prepaid rent of $5,006 on the consolidated balance sheet as landlord owned tenant improvements were determined to be lease payments and included as prepaid rent on the balance sheet.

Subsequent to the transition, construction was completed associated with approximately 10,500 square feet of the leased space in Framingham, Massachusetts and the Company occupied the building as office space beginning August 1, 2019. This space was determined to be a separate unit of account and is classified as a financing lease. The Company recorded a right-of-use asset and lease liability associated with the occupied space as of August 1, 2019. The right-of-use asset was recorded including $2,368 of prepaid rent of costs incurred prior to the commencement date. The Company occupied the remainder of the facility, approximately 53,000 square feet used as laboratory space, on October 22, 2019. The Company recorded a right-of-use asset, which included prepaid rent costs of $18,425, and lease liability associated with the occupancy on October 22, 2019.

In June 2019, the Company entered into an agreement to lease approximately 18,700 square feet of office space in Woburn, Massachusetts. Pursuant to the lease agreement, the lease term commenced in August 2019. The rent commenced in September 2019.The initial lease term is ten years from the rent commencement date and includes an optional five-year extension. Annual lease payments during the first year are $488 with increases of approximately 1.6% each year. The Company recorded a right-of-use asset and a lease liability of $4,363 upon the commencement date of the lease and the lease is classified as an operating lease.

The Company determines if an arrangement is a lease at inception. Operating leases are included in our balance sheet as right-of-use assets-operating leases, current operating lease liabilities and long-term operating lease liabilities. Finance leases are included in the balance sheet as right-of-use asset - finance lease, finance lease liabilities, current, and finance lease liabilities, non-current.Certain of the Company’s lease agreements contain renewal options; however, the Company does not recognize right-of-use assets or lease liabilities for renewal periods unless it is determined that the Company is reasonably certain of renewing the lease at inception or when a triggering event occurs. As the Company’s leases do not provide an implicit rate, the Company estimated the incremental borrowing rate in calculating the present value of the lease payments. Since the Company elected to account for each lease component and its associated non-lease components as a single combined lease component, all contract consideration was allocated to the combined lease component. Some of the Company’s lease agreements contain rent escalation clauses (including index-based escalations). The Company recognizes the minimum rental expense 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.


	Three Months Ended		Nine Months Ended
	December 31,		December 31,
	2019		2019
Lease cost
Finance lease costs:
Amortization of right-of-use asset	$	607	$	666
Interest on lease liabilities		591		652
Operating lease costs		262		633
Total lease cost	$	1,460	$	1,951

Finance lease costs of $90 and $149 are recognized in general and administrative expenses for the three and nine months ended December 31, 2019 and $517 in research and development expenses for both the three and nine months ended December 31, 2019. 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 December 31, 2019:


	December 31, 2019
	Operating lease		Financing lease		Total
2020 (remaining three months)	$	243	$	593	$	836
2021		1,034		2,411		3,445
2022		586		2,483		3,069
2023		596		2,558		3,154
2024		605		2,634		3,239
Thereafter		3,384		46,398		49,782
Total lease payments		6,448		57,077		63,525
Less: interest		1,551		29,668		31,219
Total lease liabilities	$	4,897	$	27,409	$	32,306

The following disclosure is provided for periods prior to adoption of ASU 2016-02. Future annual minimum lease payment commitments as of March 31, 2019 were as follows, which included payments for the lease agreement in Framingham, Massachusetts which has not commenced under ASC 842, and therefore has not been recorded on the Company’s condensed consolidated balance sheet as of December 31, 2019:


2020	$	2,062
2021		2,901
2022		2,493
2023		2,568
2024		2,645
2025		2,725
Thereafter		12,770
	$	28,164

The following table provides lease disclosure as of and for the three months ended December 31, 2019:


	December 31, 2019
Leases
Right-to-use operating lease asset	$	4,731
Right-to-use finance lease asset		47,528
Total lease assets	$	52,259

Operating lease liabilities, current	$	1,011
Finance lease liabilities, current		2,393
Operating lease liabilities, non-current		3,886
Finance lease liabilities, non-current		25,016
Total lease liabilities	$	32,306

Other information
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	516
Operating cash flows from finance leases	$	623
Financing cash flows from finance leases	$	22
Right-to-use asset obtained in exchange for new operating lease liabilities	$	5,152
Right-to-use asset obtained in exchange for new financing lease liabilities	$	48,224
Variable lease costs	$	—
Short term lease costs	$	—
Weighted-average remaining lease term - operating leases		8.6	years
Weighted-average remaining lease term - financing leases		19.6	years
Weighted-average discount rate - operating leases		7	%
Weighted-average discount rate - financing leases		8	%

The variable lease costs and short-term lease costs were insignificant for the three and nine months ended December 31, 2019.

Manufacturing commitments

The Company has entered into an agreement with a contract manufacturing organization to provide clinical trial products. As of December 31, 2019 and March 31, 2019, the Company had committed to minimum payments under these arrangements totaling $5,113 and $4,694 through March 31, 2020, respectively.

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 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 December 31, 2019 or March 31, 2019.

Legal Proceedings

The Company is not a party to any litigation and does not have contingency reserves established for any litigation liabilities.

Geographic Information

9 Months Ended

Dec. 31, 2019

Geographic Information

Geographic Information

13. 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 table below:


	December 31, 2019		March 31, 2019
United States	$	5,136	$	11,648
United Kingdom		518		511
	$	5,654	$	12,159

Summary of significant accounting policies (Policies)

9 Months Ended

Dec. 31, 2019

Summary of significant accounting policies

Principles of consolidation

Use of estimates

Unaudited interim financial information

Debt Issuance Costs

Recently Adopted Accounting Pronouncements

The following table summarizes the financial impact on the Company’s condensed consolidated balance sheet upon the adoption of ASU 2016-02 and the cumulative effect adjustment on April 1, 2019:


	March 31, 2019		Adjustments		April 1, 2019
Property, plant, and equipment, net	$	12,159	$	(11,514)	$	645
Right-to-use asset	$	—	$	789	$	789
Long term prepaid rent	$	—	$	5,006	$	5,006
Lease liabilities, current	$	—	$	388	$	388
Lease liabilities, non-current	$	—	$	449	$	449
Accrued expenses	$	2,801	$	(24)	$	2,777
Deferred rent, net of current portion	$	24	$	(24)	$	—
Financing obligation	$	6,561	$	(6,561)	$	—
Accumulated deficit	$	(59,766)	$	93	$	(59,673)

Recently Issued Accounting Pronouncements

Summary of significant accounting policies (Tables)

9 Months Ended

Dec. 31, 2019

Summary of significant accounting policies

Summary of financial impact on condensed consolidated balance sheet upon the adoption of ASU 2016-02 and the cumulative effect adjustment


	March 31, 2019		Adjustments		April 1, 2019
Property, plant, and equipment, net	$	12,159	$	(11,514)	$	645
Right-to-use asset	$	—	$	789	$	789
Long term prepaid rent	$	—	$	5,006	$	5,006
Lease liabilities, current	$	—	$	388	$	388
Lease liabilities, non-current	$	—	$	449	$	449
Accrued expenses	$	2,801	$	(24)	$	2,777
Deferred rent, net of current portion	$	24	$	(24)	$	—
Financing obligation	$	6,561	$	(6,561)	$	—
Accumulated deficit	$	(59,766)	$	93	$	(59,673)

Fair value of financial assets and liabilities (Tables)

9 Months Ended

Dec. 31, 2019

Fair value of financial assets and liabilities

Schedule of company's financial assets and liabilities measured at fair value on a recurring basis


	Fair Value Measurements as of
	December 31, 2019 Using:
	Level 1		Level 2		Level 3		Total
Assets
Money market funds	$	—	$	35,853	$	—	$	35,853
Commercial paper		—		42,172		—		42,172
US Government Agency bonds		—		23,158		—		23,158
US Treasury bonds		—		28,105		—		28,105
Corporate debt securities		—		34,564		—		34,564
	$	—	$	163,852	$	—	$	163,852


	Fair Value Measurements as of
	March 31, 2019 Using:
	Level 1		Level 2		Level 3		Total
Assets
Money market funds	$	—	$	2,676	$	—	$	2,676
Commercial paper		—		46,687		—		46,687
US Government Agency bonds		—		20,884		—		20,884
US Treasury bonds		—		41,057		—		41,057
Corporate debt securities		—		8,467		—		8,467
	$	—	$	119,771	$	—	$	119,771

Schedule of unobservable inputs of the warrant liability upon the conversion date


	Nine Months
	Ended
	December 31,
	2018
Risk-free interest rate		2.81	%
Expected dividend yield		0	%
Expected term (in years)		7.2
Expected volatility		64.4	%
Fair value of series seed preferred stock	$	15.00

Schedule of roll forward of the warrant liability


	Warrant
	Liability
Balance at March 31, 2018	$	1,642
Change in fair value		5,452
Conversion of convertible preferred stock warrant into common stock warrant		(7,094)
Balance at December 31, 2018	$	—

Short-term investments (Tables)

9 Months Ended

Dec. 31, 2019

Short-term investments

Schedule of short-term investments


	December 31, 2019
			Gross unrealized		Gross unrealized
	Amortized cost		gains		losses		Fair value
Commercial paper	$	42,148	$	24	$	—	$	42,172
US Government agency bonds		13,045		—		(9)		13,036
US Treasury bonds		28,107		—		(2)		28,105
Corporate debt securities		34,562		5		(3)		34,564
	$	117,862	$	29	$	(14)	$	117,877


	March 31, 2019
			Gross unrealized		Gross unrealized
	Amortized cost		gains		losses		Fair value
Commercial paper	$	46,687	$	2	$	(2)	$	46,687
US Government agency bonds		15,889		4		—		15,893
US Treasury bonds		38,047		13		—		38,060
Corporate debt securities		8,469		—		(2)		8,467
	$	109,092	$	19	$	(4)	$	109,107

Property, plant and equipment, net (Tables)

9 Months Ended

Dec. 31, 2019

Property, plant and equipment, net

Schedule of property, plant and equipment, net


	December 31,		March 31,
	2019		2019
Construction in progress	$	726	$	124
Plant and laboratory equipment		3,453		584
Leasehold improvements		368		154
Computer equipment		981		138
Office equipment		721		49
Build-to-suit lease asset		—		11,514
		6,249		12,563
Less: Accumulated depreciation and amortization		(595)		(404)
	$	5,654	$	12,159

Accrued expenses and other current liabilities (Tables)

9 Months Ended

Dec. 31, 2019

Accrued expenses and other current liabilities.

Schedule of accrued expenses and other current liabilities


	December 31,		March 31,
	2019		2019
Accrued research and development costs	$	1,416	$	530
Accrued compensation and benefits costs		2,099		1,510
Accrued professional fees		697		464
Deferred rent		—		24
Other		345		273
	$	4,557	$	2,801

Long-Term Debt (Tables)

9 Months Ended

Dec. 31, 2019

Long-Term Debt

Schedule of Long-term Debt


	December 31,
	2019
Principal amount of long-term debt	$	10,000
Unamortized debt discount		(261)
Long-term debt, net of discount	$	9,739

Schedule of future payments of long term debt

Future payments of long-term debt, as of December 31, 2019 are as follows (fiscal years):


2021	$	—
2022		527
2023		6,558
2024		2,915
Total debt payments	$	10,000

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 2
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Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Stock-Based Compensation (Tables)

9 Months Ended

Dec. 31, 2019

Stock-Based Compensation

Summary of stock option activity


		Weighted		Weighted
		Average		Average	Aggregate
	Number of	Exercise		Contractual	Intrinsic
	Shares	Price		Term (Years)	Value
Outstanding as of March 31, 2019	3,721,784	$	7.14	8.61	$	30,150
Granted	1,515,535		15.00	9.41
Exercised	(184,580)		2.60
Cancelled	(136,337)		11.26
Outstanding as of December 31, 2019	4,916,402	$	9.46	8.20	$	26,959
Options exercisable as of March 31, 2019	1,278,930	$	2.51	7.75	$	16,249
Options exercisable as of December 31, 2019	1,924,564	$	5.33	7.40	$	17,650

Schedule of stock-Based Compensation expense


	Three Months Ended				Nine Months Ended
	December 31,				December 31,
	2019		2018		2019		2018
Research and development	$	1,318	$	473	$	2,974	$	989
General and administrative		1,026		407		2,961		834
	$	2,344	$	880	$	5,935	$	1,823

Employees stock options

Stock-Based Compensation

Schedule of assumptions used to determine the grant-date fair value of stock options granted


	Three Months Ended				Nine Months Ended
	December 31,				December 31,
	2019		2018		2019		2018
Risk-free interest rate	1.68	%	2.83	%	2.17	%	2.83	%
Expected term (in years)	6.1		6.1		6.0		6.1
Expected volatility	69.7	%	63.3	%	71.0	%	61.7	%
Expected dividend yield	0	%	0	%	0	%	0	%

Net loss per share (Tables)

9 Months Ended

Dec. 31, 2019

Net loss per share

Schedule of calculation of basic and diluted net loss per share attributable to common stockholders


	Three Months Ended				Nine Months Ended
	December 31,				December 31,
	2019		2018		2019		2018
Numerator:
Net loss attributable to common stockholders	$	(16,189)	$	(7,673)	$	(36,836)	$	(24,178)
Denominator:
Weighted average common shares outstanding, basic and diluted		34,877,944		31,577,313		32,742,148		20,433,580
Net loss per share attributable to common stockholders, basic and diluted	$	(0.46)	$	(0.24)	$	(1.13)	$	(1.18)

Schedule of anti-dilutive securities excluded from the computation of diluted net loss per share attributable to common shareholders


	Three and Nine Months Ended
	December 31,
	2019	2018
Options to purchase common stock	4,916,402	3,673,535
Warrants to purchase convertible preferred stock (as converted to common stock)	497,344	497,344
	5,413,746	4,170,879

Commitments and contingencies (Tables)

9 Months Ended

Dec. 31, 2019

Commitments and contingencies

Schedule of variable lease components


	Three Months Ended		Nine Months Ended
	December 31,		December 31,
	2019		2019
Lease cost
Finance lease costs:
Amortization of right-of-use asset	$	607	$	666
Interest on lease liabilities		591		652
Operating lease costs		262		633
Total lease cost	$	1,460	$	1,951

Summary of the maturity of company's lease liabilities


	December 31, 2019
	Operating lease		Financing lease		Total
2020 (remaining three months)	$	243	$	593	$	836
2021		1,034		2,411		3,445
2022		586		2,483		3,069
2023		596		2,558		3,154
2024		605		2,634		3,239
Thereafter		3,384		46,398		49,782
Total lease payments		6,448		57,077		63,525
Less: interest		1,551		29,668		31,219
Total lease liabilities	$	4,897	$	27,409	$	32,306

Schedule of future annual minimum lease payment commitments


2020	$	2,062
2021		2,901
2022		2,493
2023		2,568
2024		2,645
2025		2,725
Thereafter		12,770
	$	28,164

Schedule of additional information related to leases


	December 31, 2019
Leases
Right-to-use operating lease asset	$	4,731
Right-to-use finance lease asset		47,528
Total lease assets	$	52,259

Operating lease liabilities, current	$	1,011
Finance lease liabilities, current		2,393
Operating lease liabilities, non-current		3,886
Finance lease liabilities, non-current		25,016
Total lease liabilities	$	32,306

Other information
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	516
Operating cash flows from finance leases	$	623
Financing cash flows from finance leases	$	22
Right-to-use asset obtained in exchange for new operating lease liabilities	$	5,152
Right-to-use asset obtained in exchange for new financing lease liabilities	$	48,224
Variable lease costs	$	—
Short term lease costs	$	—
Weighted-average remaining lease term - operating leases		8.6	years
Weighted-average remaining lease term - financing leases		19.6	years
Weighted-average discount rate - operating leases		7	%
Weighted-average discount rate - financing leases		8	%

Geographic Information (Tables)

9 Months Ended

Dec. 31, 2019

Geographic Information

Summary of company's long-lived assets held in different geographic regions


	December 31, 2019		March 31, 2019
United States	$	5,136	$	11,648
United Kingdom		518		511
	$	5,654	$	12,159

Nature of the business (Details) $ / shares in Units, $ in Thousands					1 Months Ended	3 Months Ended						9 Months Ended
	Jul. 30, 2018 USD ($) $ / shares shares	Jul. 24, 2018 USD ($) $ / shares shares	Jul. 09, 2018 shares	Jul. 10, 2017	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($) $ / shares	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares	Mar. 31, 2019 USD ($) $ / shares shares
Shares issued in exchange of shares in Replimune Group, Inc				1
Ratio of replacement warrants to capital stock				1
Forward stock split ratio for each common stock			0.100534
Common stock, authorized \| shares			27,314,288		150,000,000	150,000,000						150,000,000		150,000,000
Proceeds from issuance of common stock in initial public offering, net of underwriting fees and discounts													$ 103,341
Issuance costs and underwriter fees												$ 355	2,157
Common stock, par value (in dollars per share) \| $ / shares					$ 0.001	$ 0.001						$ 0.001		$ 0.001
Repurchase of class A common stock upon closing of initial public offering (in shares) \| shares		26,258
Net loss						$ (16,189)	$ (11,139)	$ (9,508)	$ (7,673)	$ (6,461)	$ (10,044)	$ (36,836)	$ (24,178)
Accumulated deficit					$ (96,509)	$ (96,509)						$ (96,509)		$ (59,766)
Initial public offering
Common stock, authorized \| shares		150,000,000
Shares issued \| shares		6,700,000
Shares issued price (in dollars per share) \| $ / shares	$ 15.00	$ 15.00							$ 15.00				$ 15.00
Proceeds from issuance of common stock in initial public offering, net of underwriting fees and discounts		$ 93,465
Issuance costs and underwriter fees		$ 2,157
Common stock, par value (in dollars per share) \| $ / shares		$ 0.001
Undesignated preferred stock, authorized \| shares		10,000,000			10,000,000	10,000,000						10,000,000		10,000,000
Preferred stock, Par Value (in dollars per share) \| $ / shares		$ 0.001			$ 0.001	$ 0.001						$ 0.001		$ 0.001
Underwriter rights
Shares issued \| shares	707,936
Shares issued price (in dollars per share) \| $ / shares	$ 15.00
Proceeds from issuance of common stock in initial public offering, net of underwriting fees and discounts	$ 9,876
Issuance costs and underwriter fees					$ 5,814

Summary of significant accounting policies (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Oct. 22, 2019	Aug. 01, 2019	Jun. 30, 2019	Apr. 01, 2019	Mar. 31, 2019
Recently adopted accounting pronouncements
Right-to-use liability	$ 4,897			$ 4,363
Property, plant and equipment, net	5,654					$ 12,159
Right-to-use asset	4,731	$ 18,425	$ 2,368
Lease liabilities, current	1,011
Lease liabilities, non-current	3,886
Accrued expenses	4,557					2,801
Deferred rent, net of current portion						24
Financing obligation						6,561
Accumulated deficit	$ (96,509)					$ (59,766)
ASU 2016-02
Recently adopted accounting pronouncements
Right-to-use liability					$ 837
Property, plant and equipment, net					645
Right-to-use asset					789
Long term prepaid rent					5,006
Lease liabilities, current					388
Lease liabilities, non-current					449
Accrued expenses					2,777
Accumulated deficit					(59,673)
ASU 2016-02 \| Adjustments
Recently adopted accounting pronouncements
Property, plant and equipment, net					(11,514)
Right-to-use asset					789
Long term prepaid rent					5,006
Lease liabilities, current					388
Lease liabilities, non-current					449
Accrued expenses					(24)
Deferred rent, net of current portion					(24)
Financing obligation					(6,561)
Accumulated deficit					$ 93

Fair value of financial assets and liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2019
Fair value of financial assets and liabilities
Transfer from Leve 1 to Level 2, assets	$ 0	$ 0	$ 0	$ 0
Transfer from Leve 2 to Level 1, assets	0	0	0	0
Transfers into Level 3, assets	0	0	0	0
Transfer out of Level 3, assets	0	0	0	0
Transfer from Leve 1 to Level 2, liabilities	0	0	0	0
Transfer from Leve 2 to Level 1, liabilities	0	0	0	0
Transfers into Level 3, liabilities	0	0	0	0
Transfer out of Level 3, liabilities	0	$ 0	0	$ 0
Recurring
Fair value of financial assets and liabilities
Assets fair value	163,852		163,852		$ 119,771
Level 2 \| Recurring
Fair value of financial assets and liabilities
Assets fair value	163,852		163,852		119,771
Money market funds \| Recurring
Fair value of financial assets and liabilities
Assets fair value	35,853		35,853		2,676
Money market funds \| Level 2 \| Recurring
Fair value of financial assets and liabilities
Assets fair value	35,853		35,853		2,676
Commercial paper \| Recurring
Fair value of financial assets and liabilities
Assets fair value	42,172		42,172		46,687
Commercial paper \| Level 2 \| Recurring
Fair value of financial assets and liabilities
Assets fair value	42,172		42,172		46,687
US Government Agency bonds \| Recurring
Fair value of financial assets and liabilities
Assets fair value	23,158		23,158		20,884
US Government Agency bonds \| Level 2 \| Recurring
Fair value of financial assets and liabilities
Assets fair value	23,158		23,158		20,884
US Treasury bonds \| Recurring
Fair value of financial assets and liabilities
Assets fair value	28,105		28,105		41,057
US Treasury bonds \| Level 2 \| Recurring
Fair value of financial assets and liabilities
Assets fair value	28,105		28,105		41,057
Corporate debt securities \| Recurring
Fair value of financial assets and liabilities
Assets fair value	34,564		34,564		8,467
Corporate debt securities \| Level 2 \| Recurring
Fair value of financial assets and liabilities
Assets fair value	$ 34,564		$ 34,564		$ 8,467

Fair value of financial assets and liabilities - Unobservable inputs of the warrant liability (Details)	Dec. 31, 2018 $ / shares	Jul. 30, 2018 $ / shares	Jul. 24, 2018 $ / shares
Initial public offering
Unobservable inputs of the warrant liability
Fair value of series seed preferred stock (in price per share)	$ 15.00	$ 15.00	$ 15.00
Risk-free interest rate
Unobservable inputs of the warrant liability
Warrant liability inputs	2.81
Expected dividend yield
Unobservable inputs of the warrant liability
Warrant liability inputs	0
Expected term
Unobservable inputs of the warrant liability
Warrant liability inputs	7.2
Expected volatility
Unobservable inputs of the warrant liability
Warrant liability inputs	64.4

Fair value of financial assets and liabilities - Roll forward of the warrant liability (Details) - Warrant liability $ in Thousands	9 Months Ended
	Dec. 31, 2018 USD ($)
Roll forward of the warrant liability
Balance at beginning of the period	$ 1,642
Change in fair value	5,452
Conversion of convertible preferred stock warrant into common stock warrant	$ (7,094)

Short-term investments (Details) - Short-term investments - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Dec. 31, 2019	Mar. 31, 2019
Short-term investments
Amortized cost	$ 117,862	$ 109,092
Gross unrealized gains	29	19
Gross unrealized losses	(14)	(4)
Fair value	117,877	109,107
Commercial paper
Short-term investments
Amortized cost	42,148	46,687
Gross unrealized gains	24	2
Gross unrealized losses		(2)
Fair value	42,172	46,687
US Government Agency bonds
Short-term investments
Amortized cost	13,045	15,889
Gross unrealized gains		4
Gross unrealized losses	(9)
Fair value	13,036	15,893
US Treasury bonds
Short-term investments
Amortized cost	28,107	38,047
Gross unrealized gains		13
Gross unrealized losses	(2)
Fair value	28,105	38,060
Corporate debt securities
Short-term investments
Amortized cost	34,562	8,469
Gross unrealized gains	5
Gross unrealized losses	(3)	(2)
Fair value	$ 34,564	$ 8,467

Property, plant and equipment, net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Apr. 01, 2019	Mar. 31, 2019
Property, plant and equipment, net
Property, plant and equipment , gross	$ 6,249		$ 6,249			$ 12,563
Less: Accumulated depreciation and amortization	(595)		(595)			(404)
Property, plant and equipment , net	5,654		5,654			12,159
Depreciation and amortization expense	107	$ 37	191	$ 106
Financing obligation						6,561
ASU 2016-02
Property, plant and equipment, net
Property, plant and equipment , net					$ 645
Long term prepaid rent					5,006
ASU 2016-02 \| Adjustments
Property, plant and equipment, net
Property, plant and equipment , net					(11,514)
Financing obligation					(6,561)
Long term prepaid rent					$ 5,006
Construction in progress
Property, plant and equipment, net
Property, plant and equipment , gross	726		726			124
Plant and laboratory equipment
Property, plant and equipment, net
Property, plant and equipment , gross	3,453		3,453			584
Leasehold improvements
Property, plant and equipment, net
Property, plant and equipment , gross	368		368			154
Property, plant and equipment , net						11,514
Computer equipment
Property, plant and equipment, net
Property, plant and equipment , gross	981		981			138
Office equipment
Property, plant and equipment, net
Property, plant and equipment , gross	$ 721		$ 721			49
Build-to-suit lease asset
Property, plant and equipment, net
Property, plant and equipment , gross						$ 11,514

Accrued expenses and other current liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Accrued expenses and other current liabilities.
Accrued research and development costs	$ 1,416	$ 530
Accrued compensation and benefits costs	2,099	1,510
Accrued professional fees	697	464
Deferred rent		24
Other	345	273
Total	$ 4,557	$ 2,801

Long-Term Debt (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Long-Term Debt
Principal amount of long-term debt	$ 10,000
Unamortized debt discount	(261)
Long-term debt, net of discount	$ 9,739

Long-Term Debt - Hercules Loan Agreement (Details) $ in Thousands		1 Months Ended	3 Months Ended	5 Months Ended	9 Months Ended
	Aug. 08, 2019 USD ($) item	Aug. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Debt Securities
Unamortized debt discount			$ 261	$ 261	$ 261
Long Term Debt Due Charges					495
Term Loan Agreement
Debt Securities
Maximum borrowing capacity	$ 30,000
Borrowed amount	10,000
Facility charge	225
Additional closing and legal fees	130
Unused borrowing capacity available under the facility	$ 20,000
Number of separate advances available to be borrowed under the unused facility \| item	2
Interest rate		8.75%
Term (in years)		4 years
Percentage of prepayment charge payable within the first twelve months		3.00%
Percentage of prepayment charge payable after twelve months but prior to twenty four months		2.00%
Percentage of prepayment charge payable anytime thereafter		1.00%
Percentage of charge Payable on aggregate debt amount		4.95%
Upfront fees, including closing costs and legal fees		$ 355
Interest expense			302		376
Non-cash interest expense related to accretion of the debt discount			81		94
Unamortized debt discount			261	$ 261	261
Interest Rate				10.10%
Principal payments due or paid			$ 0	$ 0	$ 0
Term loan agreement, second advance
Debt Securities
Maximum borrowing capacity	$ 10,000
Term loan agreement, third advance
Debt Securities
Maximum borrowing capacity	$ 10,000
Prime Rate \| Term Loan Agreement
Debt Securities
Variable interest rate		2.75%

Long-Term Debt - Future payments of long-term debt (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Long-Term Debt
2022	$ 527
2023	6,558
2024	2,915
Total debt payments	$ 10,000

Stockholders' Equity (Details) - $ / shares	Jul. 24, 2018	Dec. 31, 2019	Mar. 31, 2019	Jul. 09, 2018
Stockholders' Equity
Shares authorized (in shares)		150,000,000	150,000,000	27,314,288
Par value (in dollars per share)		$ 0.001	$ 0.001
Repurchase of class A common stock upon closing of initial public offering (in shares)	26,258
Initial public offering
Stockholders' Equity
Shares authorized (in shares)	150,000,000
Par value (in dollars per share)	$ 0.001
Undesignated preferred stock, authorized	10,000,000	10,000,000	10,000,000
Preferred stock, Par Value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001
Undesignated preferred shares issued		0	0
Undesignated preferred shares outstanding		0	0
Common stock
Stockholders' Equity
Common stock reserved for the conversion of outstanding shares of preferred stock		10,472,126	6,873,744

Stockholders' Equity - Convertible preferred stock (Details) $ in Thousands	Jul. 25, 2018 shares	Jul. 09, 2018	Dec. 31, 2019 USD ($)
Convertible preferred stock
Forward stock split ratio for each common stock		0.100534
Preferred stock outstanding \| $			$ 0
Common stock
Convertible preferred stock
Conversion of shares (in shares) \| shares	19,157,360

Stockholders' Equity - Preferred stock warrants (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Jul. 24, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Preferred stock warrants
Loss from change in fair value of the warrant liability					$ 5,452
Series seed preferred stock
Preferred stock warrants
Number of preferred stock warrants issued		50,000		50,000
Exercise price (in dollars per share)		$ 10.00		$ 10.00
Fair value of the warrants to purchase shares of series seed preferred stock		$ 391		$ 391
Preferred stock warrants, exercisable	497,344
Other income (expense), net
Preferred stock warrants
Loss from change in fair value of the warrant liability		$ 0	$ 0	$ 0	$ (5,452)

Stockholders' Equity - ATM Program (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended	9 Months Ended
	Dec. 31, 2019	Aug. 31, 2019	Dec. 31, 2019	Dec. 31, 2019	Mar. 31, 2019
Class of Warrant or Right [Line Items]
Common stock, par value (in dollars per share)	$ 0.001		$ 0.001	$ 0.001	$ 0.001
Net proceeds	$ 85,598
ATM sales
Class of Warrant or Right [Line Items]
Issuance of stock (value)			$ 4,431
Common stock, par value (in dollars per share)		$ 0.001
Percentage Of Commission		3.00%
Common stock sold				287,559
Gross proceeds				$ 4,568
Legal fees				137
Net proceeds				$ 4,431
ATM sales \| Maximum
Class of Warrant or Right [Line Items]
Issuance of stock (value)		$ 75,000
Securities offered to the public during the period		$ 250,000

Stockholders' Equity - Equity offerings (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		9 Months Ended
	Dec. 31, 2019	Nov. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Class of Warrant or Right [Line Items]
Public offering price		$ 13.61
Variation between public offering prices of common stock and pre-funded warrants		$ 0.0001
Net proceeds from sale of stock	$ 85,598
Issuance costs and underwriter fees			$ 355	$ 2,157
Pre-Funded Warrants [Member]
Class of Warrant or Right [Line Items]
Issuance of pre-funded warrants		2,200,000
Pre-funded warrants exercise price		$ 13.6099
Maximum percentage of holding for exercise warrants		9.99%
Prior notice period to change percentage of holding		61 days
Underwriter rights
Class of Warrant or Right [Line Items]
Common stock sold	838,530	3,678,031
Number of days for purchase shares		30 days
Maximum additional shares to purchase		881,704
Issuance costs and underwriter fees	$ 5,814

Stock Based Compensation (Details) - shares			9 Months Ended
Stock Based Compensation (Details) - shares	Apr. 01, 2019	Jul. 09, 2018	Dec. 31, 2019
2017 Plan
Share based payments
Shares authorized (in shares)			2,659,885
Number of shares available for grant		2,520,247	0
Common stock reserved for issuance		131,850
2018 Plan
Share based payments
Shares authorized (in shares)		3,617,968
Number of shares available for grant			2,193,176
Common stock reserved for issuance		3,486,118
Additional shares authorized (in shares)	1,266,370
ESPP
Share based payments
Common stock reserved for issuance	665,204	348,612
Share based payment award percentage of outstanding shares		1.00%
Additional shares authorized (in shares)	316,592	697,224
Employees stock options
Share based payments
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
Employees stock options \| Minimum
Share based payments
Expiration period for persons holding more than ten percent of voting power			10 years
Employees stock options \| Maximum
Share based payments
Expiration period for persons holding ten percent of voting power			5 years

Stock Based Compensation - Assumptions to determine grant-date fair value of stock options (Details)	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Stock-Based Compensation
Risk-free interest rate	1.68%	2.83%	2.17%	2.83%
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days	6 years	6 years 1 month 6 days
Expected volatility	69.70%	63.30%	71.00%	61.70%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

Stock Based Compensation - Stock option activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2019
Number of Shares
Outstanding at beginning of the period (in shares)			3,721,784
Granted (in shares)			1,515,535
Exercised (in shares)			(184,580)
Cancelled (in shares)			(136,337)
Outstanding at end of the period (in shares)	4,916,402		4,916,402		3,721,784
Options exercisable (in shares)	1,924,564		1,924,564		1,278,930
Weighted Average Exercise Price
Outstanding at beginning of the period (in dollars per share)			$ 7.14
Granted (in dollars per share)			15.00
Exercised (in dollars per share)			2.60
Cancelled (in dollars per share)			11.26
Outstanding at end of the period (in dollars per share)	$ 9.46		9.46		$ 7.14
Options exercisable (in dollars per share)	$ 5.33		$ 5.33		$ 2.51
Weighted Average Contractual Term (Years)
Outstanding (years)			8 years 2 months 12 days		8 years 7 months 10 days
Granted (years)			9 years 4 months 28 days
Options exercisable (years)			7 years 4 months 24 days		7 years 9 months
Aggregate Intrinsic Value
Outstanding at beginning of the period			$ 30,150
Outstanding at end of the period	$ 26,959		26,959		$ 30,150
Options exercisable	17,650		17,650		$ 16,249
Total fair value of options vested	$ 1,063	$ 211	$ 4,480	$ 1,042
Outstanding unvested service-based stock options	0		0

Stock Based Compensation - Classification of expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Share-Based Compensation
Stock-based compensation expense	$ 2,344	$ 880	$ 5,935	$ 1,823
Total unrecognized compensation cost	18,483		$ 18,483
Expenses expected to be recognized over a weighted average remaining period			2 years 8 months 12 days
Research and development expenses
Share-Based Compensation
Stock-based compensation expense	1,318	473	$ 2,974	989
General and administrative expenses
Share-Based Compensation
Stock-based compensation expense	$ 1,026	$ 407	$ 2,961	$ 834

Net loss per share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net loss attributable to common stockholders	$ (16,189)	$ (7,673)	$ (36,836)	$ (24,178)
Denominator:
Weighted average common shares outstanding, basic and diluted (in shares)	34,877,944	31,577,313	32,742,148	20,433,580
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.46)	$ (0.24)	$ (1.13)	$ (1.18)

Net loss per share - Computation of diluted net loss per share attributable to common stockholders (Details) - shares	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Diluted net loss per share attributable to common stockholders
Antidilutive securities excluded from computation of diluted weighted average shares outstanding	5,413,746	4,170,879	5,413,746	4,170,879
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	4,916,402	3,673,535	4,916,402	3,673,535
Warrant liability
Diluted net loss per share attributable to common stockholders
Antidilutive securities excluded from computation of diluted weighted average shares outstanding	497,344	497,344	497,344	497,344

Significant agreements (Details) $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended
Significant agreements (Details) $ in Thousands	Jan. 31, 2020 item	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)
Significant agreements
Prepaid expenses and other current assets		$ 5,220	$ 5,220	$ 3,696
Regeneron Pharmaceuticals, Inc
Significant agreements
Payments received under the terms of the agreement		760	2,008
Prepaid expenses and other current assets		$ 1,017	$ 1,017	$ 337
Bristol-Myers Squibb Company [Member]
Significant agreements
Number Of Patients \| item	125

Commitments and contingencies - Lease agreements (Details) $ in Thousands			1 Months Ended				3 Months Ended	9 Months Ended		30 Months Ended
	Oct. 22, 2019 USD ($) ft²	Aug. 01, 2019 USD ($) ft²	Jun. 30, 2019 USD ($) ft²	Jun. 30, 2018 USD ($) ft² Option	Apr. 30, 2016	Dec. 31, 2015 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2019 USD ($)	Apr. 01, 2019 USD ($)	Mar. 31, 2019 USD ($)
Lease agreements
Number of options to extend lease agreement (in years)						5 years
Monthly lease payments, inclusive of base rent and ancillary charges						$ 7
Prior notice period upon termination of lease					9 months
Base rent of monthly lease payments									$ 23	$ 31
Leased office space \| ft²	53,000	10,500	18,700	63,000
Rentable office space \| ft²				106,000
Lease term			10 years	10 years						10 years
Number of options to renewal the lease \| Option				2
Renewal period of lease			5 years	5 years						5 years
Annual rental payment			$ 488	$ 2,373
Percentage of annual increase in lease rental expenses			1.60%	3.00%						1.60%
Property, plant and equipment, net							$ 5,654	$ 5,654				$ 12,159
Financing obligation												6,561
Right-to-use asset	$ 18,425	$ 2,368					4,731	4,731
Right-to-use liability			$ 4,363				4,897	4,897		$ 4,363
Operating lease, remained payable							516
ASU 2016-02
Lease agreements
Property, plant and equipment, net											$ 645
Long term prepaid rent											5,006
Right-to-use asset											789
Right-to-use liability											$ 837
General and administrative expenses
Lease agreements
Finance Lease Cost							90	149
Research and development expenses
Lease agreements
Finance Lease Cost							$ 517	$ 517
Leasehold improvements
Lease agreements
Property, plant and equipment, net												$ 11,514

Commitments and contingencies - Components of lease expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Dec. 31, 2019	Dec. 31, 2019
Finance lease costs:
Amortization of right-of-use asset	$ 607	$ 666
Interest on lease liabilities	591	652
Operating lease costs	262	633
Total lease cost	$ 1,460	$ 1,951

Commitments and contingencies - Future lease payments under operating and financing lease liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jun. 30, 2019
Operating lease
2020 (remaining three months)	$ 243
2021	1,034
2022	586
2023	596
2024	605
Thereafter	3,384
Total lease payments	6,448
Less: interest	1,551
Total lease liabilities	4,897	$ 4,363
Financing lease
2020 (remaining three months)	593
2021	2,411
2022	2,483
2023	2,558
2024	2,634
Thereafter	46,398
Total lease payments	57,077
Less: interest	29,668
Total lease liabilities	27,409
Total
2020 (remaining three months)	836
2021	3,445
2022	3,069
2023	3,154
2024	3,239
Thereafter	49,782
Total lease payments	63,525
Less: interest	31,219
Total lease liabilities	$ 32,306

Commitments and contingencies - Future annual minimum lease payment commitments (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Commitments and contingencies
2020	$ 2,062
2021	2,901
2022	2,493
2023	2,568
2024	2,645
2025	2,725
Thereafter	12,770
Total	$ 28,164

Commitments and contingencies - Additional information related to leases (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Oct. 22, 2019	Aug. 01, 2019
Leases
Right-to-use operating lease asset	$ 4,731	$ 4,731	$ 18,425	$ 2,368
Right-to-use financing lease asset	47,528	47,528
Total lease assets	52,259	52,259
Operating lease liabilities, current	1,011	1,011
Finance lease liabilities, current	2,393	2,393
Operating lease liabilities, non-current	3,886	3,886
Finance lease liabilities, non-current	25,016	25,016
Total lease liabilities	32,306	32,306
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	516
Operating cash flows from finance leases	623
Financing cash flows from finance leases	22	22
Right-to-use asset obtained in exchange for new operating lease liabilities	5,152	5,152
Right-to-use asset obtained in exchange for new financing lease liabilities	$ 48,224	$ 48,224
Weighted-average remaining lease term - operating leases	8 years 7 months 6 days	8 years 7 months 6 days
Weighted-average remaining lease term - financing leases	19 years 7 months 6 days	19 years 7 months 6 days
Weighted-average discount rate - operating leases	7.00%	7.00%
Weighted-average discount rate - financing leases	8.00%	8.00%

Geographic Information (Details) $ in Thousands	9 Months Ended
Geographic Information (Details) $ in Thousands	Dec. 31, 2019 USD ($) segment	Mar. 31, 2019 USD ($)
Geographic information
Number of operating geographic regions \| segment	2
Long-lived assets	$ 5,654	$ 12,159
United States
Geographic information
Long-lived assets	5,136	11,648
United Kingdom
Geographic information
Long-lived assets	$ 518	$ 511

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEICIT (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Sep. 30, 2018
Prefunded common stock warrants
Issuance costs and underwriter fees	$ 1,797
Common stock \| Follow-on public offering
Issuance costs and underwriter fees	$ 4,017
Common stock \| Initial public offering
Issuance costs and underwriter fees		$ 9,935

Subsequent Events	9 Months Ended
Subsequent Events	Dec. 31, 2019
Subsequent Events
Subsequent Events	14. Subsequent Events Agreement with Bristol- Myers Squibb Company In January 2020, the Company and BMS expanded the scope of the Clinical Trial Collaboration and Supply Agreement to provide that BMS will supply to the Company, at no cost, nivolumab for use in combination with RP1 in an additional cohort of 125 patients with anti-PD1 refractory melanoma.

Commitments and contingencies - Manufacturing commitments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Commitments and contingencies
Minimum payments committed to manufacturing organization	$ 5,113	$ 4,694

Subsequent Events (Details)-ol	1 Months Ended
Subsequent Events (Details)-ol	Jan. 31, 2020 item
Subsequent events
Subsequent Event [Line Items]
Number Of Patients	125