Sio Gene Therapies (SIOX) 10-K 11 Jun 18 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Mar. 31, 2018	Jun. 07, 2018	Sep. 30, 2017
Document and Entity Information
Entity Registrant Name	Axovant Sciences Ltd.
Entity Central Index Key	1,636,050
Document Type	10-K
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--03-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		107,788,074
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Public Float			$ 220,577,004

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Current assets:
Cash	$ 154,337	$ 212,573
Prepaid expenses and other current assets	2,174	6,457
Income tax receivable	1,751	658
Total current assets	158,262	219,688
Property and equipment, net	2,524	142
Deferred tax assets	0	2,709
Total assets	160,786	222,539
Current liabilities:
Accounts payable	3,949	8,551
Due to Roivant Sciences Ltd., Roivant Sciences, Inc. and Roivant Sciences GmbH	1,011	2,919
Accrued expenses	31,862	34,796
Current portion of long term debt	9,753	0
Total current liabilities	46,575	46,266
Long term debt	42,925	51,436
Total liabilities	89,500	97,702
Commitments and contingencies (Note 10)
Shareholders’ equity:
Common shares, par value $0.00001 per share, 1,000,000,000 shares authorized, 107,788,074 and 99,163,919 issued and outstanding at March 31, 2018 and March 31, 2017, respectively	1	1
Accumulated other comprehensive income	126	378
Additional paid-in capital	628,110	459,601
Accumulated deficit	(556,951)	(335,143)
Total shareholders’ equity	71,286	124,837
Total liabilities and shareholders’ equity	$ 160,786	$ 222,539

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015	Mar. 19, 2015	Mar. 18, 2015	Oct. 31, 2014
Common stock
Common shares par value (in dollars per share)	$ 0.00001	$ 0.00001			$ 0.00001	$ 1	$ 1
Common shares authorized (in shares)	1,000,000,000	1,000,000,000			1,000,000,000	10,000	10,000
Common shares issued (in shares)	107,788,074	99,163,919		75,000,000	75,000,000	750
Common shares outstanding (in shares)	107,788,074	99,163,919	75,000,000			750

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Operating expenses:
Research and development expenses	$ 141,412	$ 134,778	$ 76,644
General and administrative expenses	71,906	45,721	56,518
Total operating expenses	213,318	180,499	133,162
Interest expense	7,545	1,143	0
Other (income) expense	(211)	369	0
Loss before income tax expense (benefit)	(220,652)	(182,011)	(133,162)
Income tax expense (benefit)	921	(1,060)	(17)
Net loss	$ (221,573)	$ (180,951)	$ (133,145)
Net loss per common share — basic and diluted (in dollars per share)	$ (2.06)	$ (1.82)	$ (1.41)
Weighted average common shares outstanding - basic and diluted (in shares)	107,375,927	99,158,699	94,465,164

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Research and development
Share-based compensation	$ 16,597	$ 19,186	$ 30,622
General and administrative
Share-based compensation	$ 15,281	$ 17,184	$ 41,764

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (221,573)	$ (180,951)	$ (133,145)
Other comprehensive (loss) income:
Foreign currency translation adjustment	(252)	378	0
Total other comprehensive (loss) income	(252)	378	0
Comprehensive loss	$ (221,825)	$ (180,573)	$ (133,145)

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Shares	Common Shares Subscribed	Additional Paid in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance at Mar. 31, 2015	$ (7,751)	$ 1	$ (1)	$ 13,296	$ (21,047)	$ 0
Balance (in shares) at Mar. 31, 2015		75,000,000
Increase (Decrease) in Shareholders' Equity (Deficit)
Exercise of stock options (in shares)	0
Stock issued	$ 334,502			334,502
Stock issued (in shares)		24,150,000
Common shares subscription paid	1		1
Capital contribution	750			750
Share-based compensation expense	17,994			17,994
Capital contribution — share-based compensation	54,392			54,392
Foreign currency translation adjustment	0
Net loss	(133,145)				(133,145)
Balance at Mar. 31, 2016	266,743	$ 1	0	420,934	(154,192)	0
Balance (in shares) at Mar. 31, 2016		99,150,000
Increase (Decrease) in Shareholders' Equity (Deficit)
Exercise of stock options	$ 36			36
Exercise of stock options (in shares)	13,919	13,919
Warrant issued with debt financing	$ 2,261			2,261
Share-based compensation expense	25,449			25,449
Capital contribution — share-based compensation	10,921			10,921
Foreign currency translation adjustment	378					378
Net loss	(180,951)				(180,951)
Balance at Mar. 31, 2017	124,837	$ 1	0	459,601	(335,143)	378
Balance (in shares) at Mar. 31, 2017		99,163,919
Increase (Decrease) in Shareholders' Equity (Deficit)
Adjustment to adopt ASU 2016-09				235	(235)
Exercise of stock options	$ 1,557			1,557
Exercise of stock options (in shares)	740,823	740,823
Exercise of warrant	$ 0	$ 0
Exercise of warrant (in shares)		129,827
Stock issued	134,515			134,515
Stock issued (in shares)		7,753,505
Capital contribution	324			324
Share-based compensation expense	26,465			26,465
Capital contribution — share-based compensation	5,413			5,413
Foreign currency translation adjustment	(252)					(252)
Net loss	(221,573)				(221,573)
Balance at Mar. 31, 2018	$ 71,286	$ 1	$ 0	$ 628,110	$ (556,951)	$ 126
Balance (in shares) at Mar. 31, 2018		107,788,074

Consolidated Statements of Sha8

Consolidated Statements of Shareholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	Jun. 16, 2015	Mar. 31, 2018	Mar. 31, 2016
Common stock
Sale of common stock in IPO (in dollars per share)			$ 15
Underwriting discounts, commissions and offering expenses	$ 27,700	$ 9,200	$ 27,748

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net loss	$ (221,573)	$ (180,951)	$ (133,145)
Adjustments to reconcile net loss to net cash used in operating activities:
In-process research and development expenses	0	0	5,252
Disposal of fixed assets	24	0	0
Foreign currency translation adjustment	(252)	378	0
Share-based compensation	31,878	36,370	72,386
Depreciation and amortization	3,083	249	14
Deferred tax assets	2,709	(2,386)	(323)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	4,283	(1,592)	(4,860)
Income tax receivable	(1,093)	312	(1,155)
Accounts payable	(4,602)	7,929	219
Due to Roivant Sciences Ltd., Roivant Sciences, Inc. and Roivant Sciences GmbH	(1,871)	1,105	(311)
Accrued expenses	(2,934)	26,477	8,391
Income tax payable	0	0	185
Net cash used in operating activities	(190,348)	(112,109)	(53,347)
Cash flows from investing activities:
Purchase of in-process research and development	0	0	(5,252)
Purchases of property and equipment	(4,284)	(105)	(94)
Net cash used in investing activities	(4,284)	(105)	(5,346)
Cash flows from financing activities:
Cash proceeds from issuance of common shares in initial public offering, net of underwriting discount	0	0	336,893
Initial public offering costs paid	0	0	(2,351)
Capital contribution from Roivant Sciences Ltd.	324	0	751
Repayment of amounts due to Roivant Sciences Ltd. and Roivant Sciences, Inc. for amounts paid on behalf of the Company	0	0	(627)
Due to Roivant Sciences Ltd. and Roivant Sciences, Inc. for amounts paid on behalf of the Company	0	0	278
Payment of contingent liability	0	(5,000)	0
Exercise of stock options	1,557	36	0
Cash proceeds from debt financing, net of financing costs	0	53,500		$ 0
Cash proceeds from issuance of common shares, net of costs	134,515	0		0
Net cash provided by financing activities	136,396	48,536	334,944
Net change in cash	(58,236)	(63,678)	276,251
Cash—beginning of year	212,573	276,251	0
Cash—end of year	154,337	212,573	276,251	0
Non-cash financing activities:
Recognition of warrant issued in debt financing	0	2,261	0
Issuance of common stock upon issuance of warrant	2,594	0		$ 0
Supplemental disclosure of cash paid:
Income taxes	377	1,014	1,279
Interest	$ 6,365	$ 435	$ 0

Description of Business

Description of Business	12 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business Axovant Sciences Ltd., inclusive of its wholly-owned subsidiaries (the ‘‘Company’’), is a clinical-stage biopharmaceutical company focused on the acquisition, development and commercialization of novel therapeutics in the fields of neurology and psychiatry . The Company is developing a pipeline of clinical and nonclinical product candidates that focuses on the various aspects of debilitating neurodegenerative diseases such as Parkinson’s disease, Alzheimer's disease, Lewy body dementia and other indications in the fields of neurology and psychiatry. The Company’s goal is to be the leading biopharmaceutical company focused on the fields of neurology and psychiatry. The Company was founded on October 31, 2014 as a Bermuda Exempted Limited Company and a wholly-owned subsidiary of Roivant Sciences Ltd. (‘‘RSL’’), under the name Roivant Neurosciences Ltd. The Company changed its name to Axovant Sciences Ltd. in March 2015. On February 24, 2015, Axovant Sciences, Inc. (“ASI”) was formed, and on March 7, 2015 it became a wholly-owned subsidiary of the Company based in the United States of America. In August 2016, the Company incorporated as its wholly-owned subsidiaries Axovant Holdings Limited ("AHL"), a private limited company incorporated under the laws of England and Wales, and Axovant Sciences GmbH ("ASG"), a company with limited liability formed under the laws of Switzerland. ASG holds the Company's intellectual property rights and will be the principal operating company for conducting its business. In July 2017, Axovant Sciences America, Inc. (“ASA”) was incorporated in Delaware and became a wholly-owned subsidiary of the Company. In March 2018, Axovant Treasury Holdings, Inc. was incorporated in Delaware and became a wholly-owned subsidiary of the Company and Axovant Treasury, Inc. was incorporated in Delaware and became a wholly-owned subsidiary of Axovant Treasury Holdings, Inc. From its inception, the Company has devoted substantially all of its efforts to organizing and staffing the Company, raising capital, acquiring product candidates and advancing its product candidates, intepirdine, previously referred to as RVT-101, and nelotanserin, into clinical development for patients with Alzheimer's disease or Lewy body dementia. In light of the data from recent trials, we have discontinued any further development of intepirdine, continued our clinical development of nelotanserin and pursued development of a pipeline of clinical and nonclinical product candidates. In June 2018, ASG entered into a license agreement (the “Oxford BioMedica Agreement”) with Oxford BioMedica (UK) Ltd. (“Oxford BioMedica”), pursuant to which the Company received a worldwide, exclusive, royalty-bearing, sub-licensable license under certain patents and other intellectual property controlled by Oxford BioMedica to develop and commercialize OXB-102 (now AXO-Lenti-PD) and related gene therapy products (collectively, the “Gene Therapy Products”) for all diseases and conditions. The Company’s near-term focus is to develop the gene therapy product candidate, which it refers to as AXO-Lenti-PD, as a one-time treatment for Parkinson’s disease. The Company intends to begin a Phase 1/2 study of AXO-Lenti-PD in advanced Parkinson’s disease patients before the end of 2018. The Company plans to make a determination of the overall development strategy for nelotanserin once the Company has reviewed final data from our currently ongoing Phase 2 study of nelotanserin in Phase 2 Sleep REM Behavior Disorder and completed our ongoing comprehensive clinical, regulatory and commercial review. In addition, the Company has the rights to develop RVT -104, a combination of rivastigmine and a peripheral muscarinic receptor antagonist, and is exploring the development of this product candidate as a potential treatment for patients with Alzheimer's disease or DLB. The Company has determined that it has one operating and reporting segment as it allocates resources and assesses financial performance on a consolidated basis. The Company does not expect to generate revenue unless and until it successfully completes development and obtains regulatory approval for a product. The Company believes it currently has sufficient funds to meet its financial needs for at least the next 12 months. The Company will be required to obtain further funding through other public or private offerings of its share capital, debt financing, collaboration and licensing arrangements or other sources. Adequate additional funding may not be available to the Company on acceptable terms, or at all.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies (A) Basis of Presentation: The Company’s fiscal year ends on March 31, and its fiscal quarters end on June 30, September 30, and December 31. The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (‘‘ASC’’) and Accounting Standards Update (‘‘ASU’’) of the Financial Accounting Standards Board (‘‘FASB’’). The consolidated financial statements include the accounts of the Company and ASI, AHL and ASG, its wholly-owned subsidiaries. The Company has no unconsolidated subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Certain prior year amounts have been reclassified to conform with the current period presentation. These reclassifications had no effect on the previously reported results of operations. (B) Use of Estimates: The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. The Company regularly evaluates estimates and assumptions related to the assets, liabilities, costs and expenses (including compensation expense) allocated to the Company under its services agreements with Roivant Sciences, Inc. (“RSI”) and Roivant Sciences GmbH (“RSG”), each a wholly-owned subsidiary of the Company's majority shareholder, RSL, as well as contingent liabilities, share-based compensation and research and development costs. The Company bases its estimates and assumptions on historical experience and on various other factors that it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates. (C) Risks and Uncertainties: The Company is subject to risks common to companies in the pharmaceutical industry including, but not limited to, uncertainties related to commercialization of products, regulatory approvals, dependence on key products, dependence on key customers and suppliers, and protection of intellectual property rights. (D) Concentrations of Credit Risk: Financial instruments that potentially subject the Company to concentration of credit risk include cash. At March 31, 2018, substantially all of the cash balances are deposited in four banking institutions and are all in excess of insured levels. (E) Property and Equipment: Property and equipment, consisting of leasehold improvements, furniture and fixtures, computers, software and other office equipment, is recorded at cost. Maintenance and repairs that do not improve or extend the lives of the respective assets are expensed to operations as incurred. Upon disposal, retirement or sale, the related cost and accumulated depreciation is removed from the accounts and any resulting gain or loss is included in the results of operations. Depreciation is recorded for property and equipment using the straight-line method over the estimated useful lives of the respective assets, generally three to five years, once the asset is installed and placed in service. Amortization of leasehold improvements is recorded over the shorter of the lease term or estimated useful life of the related asset. The Company reviews the recoverability of all long-lived assets, including the related useful lives, whenever events or changes in circumstances indicate that the carrying amount of a long-lived asset might not be recoverable. Recoverability is measured by comparison of the book values of the assets to future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceed their fair value, which is measured based on the projected discounted future net cash flows arising from the assets. (F) Debt Issuance Costs and Debt Discount: Debt issuance costs related to a recognized debt liability are presented on the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts, and are amortized to interest expense over the term of the related debt using the effective interest method. Further, debt discounts created as a result of the allocation of proceeds received from a debt issuance to warrants issued in conjunction with the debt issuance are amortized to interest expense under the effective interest method over the life of the recognized debt liability. (G) Research and Development Expense: Research and development costs are expensed as incurred. Clinical study costs are accrued over the service periods specified in the contracts and adjusted as necessary based upon an ongoing review of the level of effort and costs actually incurred. Payments for a product license prior to regulatory approval of the product and payments for milestones achieved prior to regulatory approval of the product are expensed in the period incurred as research and development. Milestone payments made in connection with regulatory approvals are capitalized and amortized to cost of revenue over the remaining useful life of the asset. Research and development costs primarily consist of the intellectual property and research and development materials acquired from GlaxoSmithKline (“GSK”) and Arena Pharmaceuticals GmbH (“Arena”) (See Note 3), certain costs charged by RSI and RSG under their services agreements with the Company (See Note 6) and expenses from third parties who conduct research and development activities on behalf of the Company. The Company expenses in-process research and development projects acquired as asset acquisitions which have not reached technological feasibility and which have no alternative future use. For the years ended March 31, 2018 , 2017 and 2016 , the Company recorded $141.4 million , $134.8 million and $76.6 million , respectively, of research and development expense, of which $16.6 million , $19.2 million and $30.6 million , respectively, was attributable to share-based compensation expense. (H) Income Taxes: Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and the respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance is recorded when, after consideration of all positive and negative evidence, it is not more likely than not that the Company's deferred tax assets will be realizable. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. When and if the Company were to recognize interest and penalties related to unrecognized tax benefits, they would be reported in tax expense in the consolidated statement of operations. (I) Share-Based Compensation: Share-based awards to employees and directors are valued at fair value on the date of grant and that fair value is recognized on a straight-line basis over the requisite service period of the entire award. The Company values its stock options using the Black-Scholes option pricing model. Certain assumptions need to be made with respect to utilizing the Black-Scholes option pricing model, including the expected life of the award, volatility of the underlying shares and the risk-free interest rate. The expected life of the stock options is calculated using the simplified method (based on the mid-point between the vesting date and the end of the contractual term). The risk-free interest rate is based on the rates paid on securities issued by the U.S. Treasury with a term approximating the expected life of the equity award. The expected share price volatility for the Company's common shares was estimated by taking the average historical price volatility for industry peers. As of April 1, 2017, the Company elected to change its policy from estimating forfeitures to recognizing forfeitures of awards when they occur (See Note 2(L)). Prior to this change, estimates of pre-vesting award forfeitures were based on the Company's expectations of future employee turnover and the Company adjusted its estimate of forfeitures over the requisite service period based on the extent to which actual forfeitures differed, or were expected to differ, from such estimates. Changes in estimated forfeitures were recognized through a cumulative catch-up adjustment in the period of change and impacted the amount of compensation expense to be recognized in future periods. The Company accounts for share-based payments to non-employees issued in exchange for services based upon the fair value of the equity instruments issued. Compensation expense for stock options issued to non-employees is calculated using the Black-Scholes option pricing model and is recorded over the service performance period. Options subject to vesting are required to be periodically remeasured over their service performance period, which is generally the same as the vesting period. (J) Net Loss per Common Share: Basic net loss per common share is computed by dividing the net loss applicable to common shareholders by the weighted-average number of common shares outstanding during the year. Diluted net loss per common share is computed by dividing the net loss applicable to common shareholders by the diluted weighted-average number of common shares outstanding during the year calculated in accordance with the treasury stock method. Stock options and a warrant to purchase a total of 14.1 million , 8.1 million and 5.9 million common shares were not included in the calculation of diluted weighted-average common shares outstanding for the years ended March 31, 2018 , 2017 and 2016 , respectively, because they were anti-dilutive given the net loss of the Company. (K) Financial Instruments: The Company utilizes fair value measurement guidance prescribed by accounting standards to value its financial instruments. The guidance establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company's own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company's assumptions about the inputs that market participants would use in pricing the asset or liability, and are developed based on the best information available in the circumstances. Fair value is identified as the exchange price, or exit price, representing the amount that would be received from the sale of an asset or paid to transfer a liability in an orderly transaction between market participants. As a basis for considering market participant assumptions in fair value measurements, the guidance establishes a three-tier fair value hierarchy that distinguishes among the following: • Level 1-Valuations are based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access. • Level 2-Valuations are based on quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active and models for which all significant inputs are observable, either directly or indirectly. • Level 3-Valuations are based on inputs that are unobservable (supported by little or no market activity) and significant to the overall fair value measurement. To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument's level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The Company's financial instruments include cash, accounts payable and debt. Cash and accounts payable are stated at their respective historical carrying amounts, which approximate fair value due to their short-term nature. The carrying value of the Company’s debt was $52.7 million at March 31, 2018, which approximates fair value based on current interest rates for similar types of borrowings and is in Level 2 of the fair value hierarchy. See Note 5 for the actual book carrying value of the Company's debt at March 31, 2018 . (L) Recently Issued Accounting Pronouncements: In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842)” (“ASU No. 2016-02”), which is a comprehensive new lease standard that amends various aspects of existing accounting guidance for leases. The core principle of ASU No. 2016-02 will require lessees to present the assets and liabilities that arise from leases on their balance sheets. ASU No. 2016-02 is effective for annual periods beginning after December 15, 2018, and interim periods within fiscal years beginning after December 15, 2018. Early adoption is permitted. The Company is currently evaluating ASU No. 2016-02 and its impact on the Company's consolidated financial position and results of operations. In March 2016, the FASB issued ASU No. 2016-09, “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting” (“ASU No. 2016-09”). ASU No. 2016-09 makes several modifications to Topic 718 related to the accounting for forfeitures, employer tax withholding on share-based compensation, and the financial statement presentation of excess tax benefits or deficiencies. ASU No. 2016-09 also clarifies the statement of cash flows presentation for certain components of share-based awards. The Company adopted this guidance as of April 1, 2017, using a modified retrospective transition method. As a result of the adoption of ASU No. 2016-09, the Company elected to change its policy from estimating forfeitures to recognizing forfeitures when they occur and, as a result, recorded an adjustment of $ 235,000 to increase accumulated deficit with a corresponding offset to paid in capital as of April 1, 2017. The other requirements of ASU No. 2016-09 did not have a material impact on the Company's consolidated financial statements and related disclosures. In October 2016, the FASB issued ASU No. 2016-16, “ Intra-Entity Transfers of Assets Other Than Inventory ” (“ASU No. 2016-16”). ASU No. 2016-16 requires the income tax consequences of intra-entity transfers of assets other than inventory to be recognized as current period income tax expense or benefit and removes the requirement to defer and amortize the consolidated tax consequences of intra-entity transfers. The new standard will be effective for the Company on April 1, 2018 and will be adopted using a modified retrospective approach which requires a cumulative effect adjustment to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the new standard and its impact on the Company’s consolidated financial statements and related disclosures. In January 2017, the FASB issued ASU 2017-01, ‘‘ Business Combinations (Topic 805): Clarifying the Definition of a Business ’’ (‘‘ASU No. 2017-01’’), which clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. ASU No. 2017-01 is effective for annual reporting periods beginning after December 15, 2017, and interim periods within those years, with early adoption permitted. The Company will apply the guidance to applicable transactions after the adoption date. The impact on the Company’s consolidated financial statements will depend on the facts and circumstances of any specific future transactions. In May 2017, the FASB issued ASU No. 2017-09, “ Scope of Modification Accounting ” (‘‘ASU No. 2017-09’’). ASU No. 2017-09 clarifies which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. ASU No. 2017-09 is effective for interim and annual reporting periods beginning after December 15, 2017 and early adoption is permitted. The Company does not expect that this standard will have a material impact on the Company’s consolidated financial statements and related disclosures. In February 2018, the FASB issued ASU No. 2018-02, “ Income Statement-Reporting Comprehensive Income (Topic 220) : Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income ” (“ASU No. 2018-02”). ASU No. 2018-02 allows companies to reclassify stranded tax effects resulting from the Tax Cuts and Jobs Act, from accumulated other comprehensive (loss) income to retained earnings. ASU No. 2018-02 is effective for interim and annual reporting periods beginning after December 15, 2017 and early adoption is permitted. The Company is currently evaluating the new standard and its impact on the Company’s consolidated financial statements and related disclosures. In March 2018, the FASB issued ASU No. 2018-05, “ Income Taxes (Topic 740) : Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 ,” (“ASU No. 2018-05”). ASU No. 2018-05 amends certain SEC material in Topic 740 for the income tax accounting implications of the recently issued Tax Cuts and Jobs Act. ASU No. 2018-05 is effective immediately. The Company evaluated the impact of the Act as well as the guidance of Staff Accounting Bulletin 118 and incorporated the changes into the determination of a reasonable estimate of deferred taxes and appropriate disclosures in the notes to the Company’s consolidated financial statements. The Company will continue to evaluate the impact this tax reform legislation may have on our results of operations, financial position, cash flows and related disclosures. (M) Foreign Currency: The Company has operations in the United States, the United Kingdom and Switzerland. The results of its non-U.S. dollar based functional currency operations are translated to U.S. dollars at the average exchange rates during the year. The Company’s assets and liabilities are translated using the current exchange rate as of the balance sheet date and shareholders’ equity is translated using historical rates. Adjustments resulting from the translation of the financial statements of the Company’s foreign functional currency subsidiaries into U.S. dollars are excluded from the determination of net loss and are accumulated in a separate component of shareholders’ equity. Foreign exchange transaction gains and losses are included in other (income) expense in the Company’s results of operations.

Asset Acquisitions

Asset Acquisitions	12 Months Ended
	Mar. 31, 2018
Asset Purchase Agreement
Asset Acquisitions	Asset Acquisitions (A) Intepirdine: On December 17, 2014, the Company entered into an asset purchase agreement (the “Asset Purchase Agreement”) to acquire certain intellectual property and research and development materials from GSK, which the Company initially named RVT-101, now known as intepirdine. At the date of the transaction, the Company assessed the likelihood of making a milestone payment as probable (it was made in June 2016) and recorded $5.0 million as research and development expense. In light of the data from recent trials, the Company has discontinued any further development of intepirdine. (B) Nelotanserin: On October 28, 2015, the Company acquired the global rights to nelotanserin, an inverse agonist of the 5-HT 2A receptor, from RSL. Pursuant to the terms of the Waiver and Option Agreement between RSL and the Company entered into in May 2015 (the ‘‘Waiver and Option Agreement’’), RSL granted the Company an option to acquire all of RSL’s rights, title and interest in and to the development, marketing and supply agreement for nelotanserin with Arena (the ‘‘Arena Development Agreement’’), together with any amendments and related side letters or other agreements. The option became exercisable beginning on September 16, 2015 and, if not exercised, would have expired on December 16, 2016. The Company exercised the option on October 28, 2015 and acquired all of RSL's rights, title, interests and obligations under the Arena Development Agreement for nelotanserin and accounted for the acquisition of nelotanserin as an asset acquisition. The Company recorded $5.3 million as research and development expense which reflects 110% of payments made by RSL to Arena, including a $4.0 million up-front payment, and costs incurred in connection with the development of nelotanserin, in each case pursuant to the Waiver and Option Agreement prior to the exercise of the option. The Company may be responsible for future contingent payments under the Arena Development Agreement, including up to $4.0 million in potential development milestone payments, up to $37.5 million in potential regulatory milestone payments and up to $60.0 million in potential commercial milestone payments. The Company is also obligated to purchase all commercial supplies of nelotanserin from Arena for a fixed price equal to 15% of net sales of nelotanserin. For the consideration above, the Company also received a small quantity of inventory of nelotanserin, and certain research and development historical records. The Company did not hire, or receive, any employees working on the development of nelotanserin, or any research, clinical or manufacturing equipment. Additionally, the Company did not assume from Arena any contracts, licenses or agreements between Arena and any third party with respect to nelotanserin. The Company will need to independently develop all clinical processes and procedures for future clinical studies of nelotanserin through the use of internal and external resources. As the intellectual property and inventory of nelotanserin acquired had no alternative future use on the date of acquisition, it was accounted for as an asset acquisition and the Company recorded the $5.3 million upfront payment as research and development expense related to its option exercised with RSL on October 28, 2015. (C) License Agreement with Qaam Pharmaceuticals, LLC: In August 2016, the Company entered into an exclusive license agreement with Qaam Pharmaceuticals, LLC (‘‘Qaam’’) for intellectual property covering the combination of cholinesterase inhibitors with peripheral muscarinic receptor antagonists and the Company expects to develop and, if successful, commercialize a product covered by the licensed intellectual property. The Company expects to develop RVT-104, a combination of a peripheral muscarinic receptor antagonist and high-dose rivastigmine. The Company paid an initial license fee of $0.6 million which was recorded as research and development expense in the accompanying consolidated statements of operations.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Mar. 31, 2018
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses As of March 31, 2018 and 2017 , accrued expenses consisted of the following (in thousands): March 31, 2018 March 31, 2017 Research and development expenses $ 21,855 $ 27,667 Salaries, bonuses, and other compensation expenses 7,718 3,497 Legal expenses 779 1,271 Other expenses 1,510 2,361 Total accrued expenses $ 31,862 $ 34,796

Long Term Debt

Long Term Debt	12 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Long Term Debt	Long Term Debt On February 2, 2017, the Company and its subsidiaries, AHL, ASG and ASI entered into a loan and security agreement (as amended on May 24 and September 22, 2017, the “Loan Agreement”) with Hercules Capital, Inc., (“Hercules”), under which the Company, AHL and ASG (the "Borrowers") borrowed an aggregate of $55.0 million (the “Term Loan”). Pursuant to the Loan Agreement, ASI has issued a guaranty of the Borrowers’ obligations under the Loan Agreement. The Term Loan bears interest at a variable per annum rate calculated for any day as the greater of either (i) the prime rate plus 6.80% , and (ii) 10.55% . The Term Loan has a scheduled maturity date of March 1, 2021. The Borrowers are obligated to make monthly payments of accrued interest under the Loan Agreement until September 1, 2018, followed by monthly installments of principal and interest beginning October 1, 2018 through March 1, 2021. In connection with the Loan Agreement, the Borrowers and ASI, as guarantor, granted Hercules a first position lien on substantially all of their respective assets, excluding intellectual property. Prepayment of the Term Loan is subject to penalty. On May 24, 2017, the Loan Agreement was amended such that the required minimum amount of unrestricted cash applied commencing on July 1, 2017 and is equal to the lesser of (i) $ 35.0 million (the “Applicable Amount”) plus certain aged accounts payable amounts (as further defined in the Loan Agreement) and (ii) the outstanding amount of debt under the Loan Agreement plus certain aged accounts payable (as further defined in the Loan Agreement), provided that the Applicable Amount may be lowered to $ 30 million upon the achievement of certain clinical milestones as set forth in the Loan Agreement. The Loan Agreement also includes customary events of default. Upon the occurrence of an event of default, a default interest rate of an additional 5.0% may be applied to the outstanding principal balance, and Hercules may declare all outstanding obligations immediately due and payable and take such other actions as set forth in the Loan Agreement. As of March 31, 2018, the Company was in compliance with its covenants and obligations under the Loan Agreement. In addition, for so long as the Term Loan remains outstanding, the Company shall be required to use its commercially reasonable efforts to afford Hercules the opportunity to participate in future underwritten equity offerings of the Company’s common shares up to a total of $ 3.0 million . In connection with the Loan Agreement, the Company issued a warrant to Hercules, exercisable for an aggregate of 274,086 of the Company’s common shares at an exercise price of $12.04 per share (the “Warrant”). In August 2017, Hercules exercised the Warrant on a cashless basis and received a net issuance of 129,827 of the Company's common shares. The Company has accounted for the Warrant as an equity instrument since it was indexed to the Company’s common shares and met the criteria for classification in shareholders’ equity. The relative fair value of the Warrant on the date of issuance was approximately $2.3 million and was treated as a discount to the debt. This amount will be amortized to interest expense using the effective interest method over the life of the Term Loan, which is a period of 48 months. The Company estimated the value of the Warrant using the Black-Scholes model. The key assumptions used to value the Warrant were as follows: Exercise price $ 12.04 Share price on date of issuance $ 11.96 Volatility 77.6 % Risk-free interest rate 2.27 % Expected dividend yield — % Contractual term (in years) 7 In addition, at the closing of the Term Loan, the Company paid transaction costs of $1.5 million , which were recorded as a discount on the debt and will be amortized to interest expense using the effective interest method over the life of the Term Loan, which is a period of 48 months. Outstanding debt obligations are as follows (in thousands): March 31, 2018 March 31, 2017 Principal amount $ 55,000 $ 55,000 Less: unamortized discount and debt issuance costs (2,322 ) (3,564 ) Loan payable less unamortized discount and debt issuance costs 52,678 51,436 Less: current portion of long term debt (9,753 ) — Long-term loan payable, net of current maturities $ 42,925 $ 51,436

Related Party Transactions

Related Party Transactions	12 Months Ended
	Mar. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions (A) Services Agreements: During 2015, the Company and ASI entered into a services agreement with RSI (the ‘‘Services Agreement’’) under which RSI agreed to provide certain administrative and research and development services to the Company. The Company and ASI amended and restated the Services Agreement with RSI on October 13, 2015 for the fiscal year commencing April 1, 2015. Under the Services Agreement, as amended and restated, the Company pays or reimburses RSI for any expenses it, or third parties acting on its behalf, incurs for the Company. For any general and administrative and research and development activities performed by RSI employees, RSI charges back the employee compensation expense plus a pre-determined mark-up. Employee compensation expense, inclusive of base salary and fringe benefits, is determined based upon the relative percentage of time utilized on Company matters. All other costs are billed back at cost. The accompanying audited consolidated financial statements include third-party expenses that have been paid by RSI and RSL. In February 2017, the Company and ASI amended and restated the Services Agreement, effective as of December 13, 2016, to add ASG as a services recipient. In addition, in February 2017, ASG entered into a separate services agreement with RSG, a wholly-owned subsidiary of RSL, effective as of December 13, 2016, for the provision of services by RSG to ASG in relation to the identification of potential product candidates and project management of clinical trials, as well as other services related to development, administrative and financial activities. Under the services agreements, for the years ended March 31, 2018 , 2017 and 2016 , the Company incurred expenses of $8.5 million , $7.9 million and $7.6 million , respectively, inclusive of the mark-up. For the years ended March 31, 2018 , 2017 and 2016 the Company recorded compensation arrangement expense of $0 , $41 thousand and $1.0 million provided to Vivek Ramaswamy as RSI’s Chief Executive Officer by one of RSL’s investors, respectively. (B) Information Sharing and Cooperation Agreement: In March 2015, the Company entered into an information sharing and cooperation agreement (the “Cooperation Agreement”) with RSL. The Cooperation Agreement, among other things, grants the Company a right of first review on any potential dementia-related product or investment opportunity that RSL may consider pursuing and obligates the Company to deliver periodic financial statements and other financial information to RSL and comply with other specified financial reporting requirements. On May 1, 2015, the Company received an offer notice, as defined in the Cooperation Agreement, from RSL relating to the opportunity to acquire, from Arena, certain rights to develop and market nelotanserin. On May 8, 2015, the Company entered into a Waiver and Option Agreement with RSL with respect to such opportunity and RSL entered into the Arena Development Agreement. Pursuant to the terms of the Waiver and Option Agreement, RSL granted the Company an option to acquire all of RSL’s right, title, interest and obligations in and to the Arena Development Agreement, together with any amendments and related side letters or other agreements. The option became exercisable beginning on September 16, 2015 and, if not exercised, would have expired on December 16, 2016. The Company exercised the option on October 28, 2015 (See Note 3). Following exercise of the option, the Services Agreement between the Company and RSI was applied with regard to any reimbursements made by the Company to RSL. (C) Family Relationships: Geetha Ramaswamy, MD, formerly the Vice President, Medical and Scientific Strategy for ASI, is the mother of Vivek Ramaswamy, a director of ASL, a director of RSL and a director and the Chief Executive Officer of RSI. Shankar Ramaswamy, MD, the Vice President, Global Medical Affairs of ASI, is the brother of Vivek Ramaswamy. Sarah Friedhoff, formerly Senior Business Operations and Research and Development Specialist of ASI, is the daughter of Lawrence Friedhoff, MD, PhD, formerly the Chief Development Officer of ASI and currently Chief of Research & Development of RSI. Lawrence Friedhoff, MD, PhD, Geetha Ramaswamy, MD and Sarah Friedhoff are no longer employed by ASI beginning in October 2017. Salary expenses were $267,800 , $259,167 and $239,583 for Shankar Ramaswamy, $133,900 , $259,167 and $239,583 for Geetha Ramaswamy and $38,625 , $74,167 and $42,709 for Sarah Friedhoff for the years ended March 31, 2018 , 2017 and 2016 , respectively.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Mar. 31, 2018
Stockholders' Equity Note [Abstract]
Shareholders' Equity	Shareholders’ Equity (A) Overview: The Company’s Memorandum of Association, filed on October 31, 2014 in Bermuda, authorized the issuance of one class of shares. The total number of shares which the Company was authorized to issue was 10,000 , each with a par value of $1.00 per share. Upon the Company's formation, RSL subscribed for 100 shares of the Company's share capital. On December 17, 2014, RSL paid the initial $ 5.0 million payment to GSK upon the closing of the transaction on behalf of the Company (See Note 3) which is reflected in the financial statements as an additional capital contribution. There were no additional shares issued in connection with such contributions to additional paid-in-capital as RSL owned 100% of the share ownership. On March 18, 2015, upon approval of the Board of Directors, the Company issued an additional 650 shares, increasing the total number of issued and outstanding shares to 750 , which were reflected in the accompanying financial statements as 65,000,000 and 75,000,000 , respectively, post stock split. Effective March 18, 2015, upon approval of the Board of Directors and the Company’s sole member, RSL, the Company effected a stock split of the authorized, issued and outstanding shares of the Company at a ratio of 100,000 -to-1. The stock split increased the total number of authorized shares from 10,000 to 1,000,000,000 , increased the total number of shares issued and outstanding from 750 to 75,000,000 , and decreased par value per share from $1.00 to $0.00001 . All information in the accompanying consolidated financial statements and notes thereto regarding common share amounts and prices per common share has been adjusted to reflect the application of the stock split on a retroactive basis. (B) Transactions: In April 2015, RSL made a cash capital contribution of $0.8 million . No additional common shares of the Company were issued in connection with this capital contribution. On June 16, 2015, the Company completed its initial public offering (“IPO”) of common shares. The Company sold 24,150,000 shares at a price of $15.00 per share, which included 3,150,000 common shares issued upon the full exercise of the underwriters’ option to purchase additional shares, for gross proceeds of $362.3 million . The Company received net proceeds of $334.5 million , net of an aggregate of $27.7 million in underwriting discounts and commissions and offering expenses. In April 2017, the Company issued and sold 7,753,505 common shares, including 1,011,326 common shares sold pursuant to the exercise in full of the underwriters' option to purchase additional shares, at an offering price of $18.54 per common share for gross proceeds of $143.7 million . The net proceeds to the Company were $134.5 million , after deducting underwriting discounts and commissions and offering expenses paid by the Company. In 2018, RSL incurred $0.3 million of expenses on behalf of the Company. This amount was treated as a capital contribution.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Share-Based Compensation Stock Options: In March 2015, the Company adopted its 2015 Equity Incentive Plan (the ‘‘2015 Plan’’), under which 7.5 million of the Company’s common shares were originally reserved for grant. The Company's employees, directors and consultants are eligible to receive non-qualified and incentive stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, and other stock awards under the plan. Options granted to consultants and employees generally vest over four years and have a ten -year contractual term. Options granted to members of the Board of Directors vest over three years and have a ten -year contractual term. In May 2015, the Company’s Board of Directors amended the 2015 Plan to increase the number of common shares authorized for issuance thereunder to 9.5 million common shares. The amendment of the 2015 Plan became effective upon the execution of the underwriting agreement relating to the Company's initial public offering of common shares in June 2015. On April 1, 2016, the number of common shares authorized for issuance increased automatically to 12.5 million in accordance with the 2015 Plan. On April 1, 2017, the number of common shares authorized increased automatically to 16.5 million in accordance with the 2015 Plan. In June 2017, the Company's Board of Directors amended and restated the 2015 Plan to, among other things, increase the number of common shares authorized for issuance thereunder to approximately 20.5 million common shares. The amended and restated 2015 Plan became effective upon shareholder approval in August 2017. Stock options granted under the 2015 Plan provide option holders, if approved by the Board of Directors, the right to exercise their options prior to vesting. In the event that an option holder exercises the unvested portion of any option, such unvested portion will be subject to a repurchase option held by the Company at the lower of (1) the fair market value of its common shares on the date of repurchase and (2) the exercise price of the options. Any common shares underlying such unvested portion will continue to vest in accordance with the original vesting schedule of the option. Prior to the IPO, the fair value of the Company’s common shares underlying stock options was estimated on each grant date by the Board of Directors. In order to determine the fair value of the Company’s common shares underlying granted stock options, the Board of Directors considered, among other things, valuations of the common shares prepared by an unrelated third-party valuation firm in accordance with the guidance provided by the American Institute of Certified Public Accountants Practice Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation. In connection with the Company’s IPO and after preliminary discussions with the underwriters, the Company reassessed the determination of the fair value of the common shares underlying 4,012,500 stock options granted in March 2015 and 527,500 stock options granted in April 2015. As a result, the Company determined that the fair value of the common shares as of April 13, 2015 was $ 15.00 per share, which was higher than the fair values of $ 0.90 per share and $ 1.04 per share as initially determined by the Board of Directors on the dates of grant in March 2015 and April 2015, respectively. The use of this higher share price increased both recognized and unrecognized share-based compensation expense and also impacted the valuation of the RSL awards share compensation expense (See Note 8(B)(2)). On March 1, 2018, the Board of Directors approved the repricing of 1,264,085 stock options previously granted to 51 individuals, including some now employed by RSI. The revised exercise price for these options is $1.49 , the closing price for the Company's common shares on March 1, 2018. The Company immediately recorded $ 0.1 million of additional share-based compensation expenses related to 146,370 vested options and increased unrecognized compensation related to 1,117,715 non-vested options by $ 0.5 million , which is expected to be recognized over the remaining service period of the non-vested options. At March 31, 2018 , a total of 5.6 million common shares were available for future issuance under the 2015 Plan. The Company estimated the fair value of each option on the date of grant using the Black-Scholes closed-form option-pricing model applying the weighted average assumptions in the following table: Years Ended March 31, 2018 2017 2016 Expected share price volatility 79.6 % 79.6 % 77.9 % Expected risk free interest rate 2.33 % 1.58 % 1.70 % Expected term, in years 6.50 6.30 6.58 Expected dividend yield — % — % — % The following table presents a summary of option activity and data under the Company's stock incentive plans through March 31, 2018 : Number of Options Weighted Average Exercise Price Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Life Aggregate Intrinsic Value Options outstanding at March 31, 2015 4,012,500 $ 0.90 $ 14.30 9.96 $ 56,576,250 Granted 1,983,808 12.10 11.89 — — Exercised — — — — — Forfeited (102,725 ) 4.99 13.41 — — Cancelled — — — — — Options outstanding at March 31, 2016 5,893,583 $ 4.60 $ 13.50 9.11 $ 47,172,525 Granted 2,642,500 13.08 9.06 — — Exercised (13,919 ) 2.57 13.28 — 141,796 Forfeited (682,130 ) 4.26 12.86 — — Cancelled — — — — — Options outstanding at March 31, 2017 7,840,034 $ 7.49 $ 12.06 8.49 $ 61,104,445 Granted 17,192,085 10.14 6.94 Exercised (740,823 ) 2.13 13.85 13,002,098 Forfeited (10,206,160 ) 14.66 10.07 Cancelled — — — Options outstanding at March 31, 2018 14,085,136 $ 5.51 $ 6.59 8.73 $ 1,347,255 Options vested and expected to vest at March 31, 2018 14,085,136 $ 5.51 $ 6.59 8.73 $ 1,347,255 Options exercisable at March 31, 2018 11,042,482 $ 4.70 $ 6.59 8.64 $ 1,347,255 At March 31, 2018 , there were 3.6 million vested options outstanding. (A) Stock Options Granted to Employees and Directors: During the years ended March 31, 2018 , 2017 and 2016 , the Company granted to its employees and directors a total of 16.1 million , 2.6 million and 1.8 million options, respectively, with weighted average exercise prices of $9.56 , $13.09 and $11.96 , respectively, and recorded related share-based compensation expense of $21.0 million , $23.1 million and $16.3 million , respectively. This share-based compensation expense is included in research and development and general and administrative expenses in the accompanying consolidated statements of operations. At March 31, 2018 , total unrecognized compensation expense related to non-vested options was $39.4 million and is expected to be recognized over the remaining weighted-average service period of 2.52 years . (B) Share-Based Compensation for Related Parties: (1) Stock Options Granted to Non-Employees: During the years ended March 31, 2018 , 2017 and 2016 , the Company granted stock options to purchase 1,046,600 , 86,700 and 215,000 shares, respectively, of the Company's common shares to employees of RSI as compensation for support services provided to the Company. The fair value of the stock options granted to RSI employees is accounted for by the Company in accordance with the authoritative guidance for non-employee equity awards and is remeasured on each valuation date until performance is complete using the Black-Scholes pricing model. Each award is subject to a specified vesting schedule. Compensation expense will be recognized by the Company over the required service period to earn each award. The Company recorded $4.8 million , $1.6 million and $1.1 million of share-based compensation expense, respectively, for the years ended March 31, 2018 , 2017 and 2016 . The share-based compensation was recorded as research and development and general and administrative expense in the accompanying consolidated statements of operations. The total remaining unrecognized compensation cost related to the non-vested stock options amounted to $1.1 million as of March 31, 2018 , which will be recognized over the weighted-average remaining requisite service period of 2.55 years . (2) Share-Based Compensation Allocated to the Company by RSL: The Company incurs share-based compensation expense for RSL common share awards and RSL options issued by RSL to RSL and RSI employees. Share-based compensation expense is allocated to the Company by RSL based upon the relative percentage of time utilized by RSL, RSG and RSI employees on Company matters. These share-based compensation amounts include compensation expense for awards made by BVC Ltd. (‘‘BVC’’) prior to the BVC Merger on December 4, 2015. On December 4, 2015, BVC, a non-public entity, which held a non-controlling ownership interest in RSL, the majority shareholder of the Company, was merged with and into RSL (the ‘‘BVC Merger’’), with RSL as the surviving entity. Prior to the BVC Merger, the Company recorded share-based compensation expense, in relation to the share-based awards issued by BVC to RSI employees based on the changes in fair value of share-based awards which were remeasured at each reporting period date until performance was completed. As these BVC share-based awards were not based on the Company's or RSL’s shares, they were remeasured at each reporting period date until performance was completed. As a result of the BVC Merger, all outstanding BVC share-based awards were converted into RSL common share awards, with the same vesting and forfeiture terms as the original grant. The RSL common share awards and RSL options are fair valued on the date of grant and that fair value is recognized over the requisite service period. On December 8, 2015 following the BVC Merger, RSL was recapitalized in conjunction with a private financing. The estimated fair value of these RSL common share awards was determined by the valuation of RSL in the December 8, 2015 private financing. As RSL is a non-public entity, the majority of the inputs used to estimate the fair value of the BVC awards prior to the BVC Merger and the RSL common share awards following the BVC Merger are classified as level 3 due to their unobservable nature. Significant judgment and estimates were used to estimate the fair value of these RSL awards and RSL options, as they are not publicly traded. RSL common share awards and RSL options are subject to specified vesting schedules and requirements (a mix of time-based and performance-based events). The fair value is based on various corporate event-based considerations, including targets for RSL’s post-IPO market capitalization and future financing events. The fair value of each RSL option is estimated on the date of grant using the Black-Scholes closed-form option-pricing model. The Company recorded share-based compensation expense of $5.4 million , $10.9 million and $53.4 million , respectively, for the years ended March 31, 2018 , 2017 and 2016 , in relation to the RSL common share awards and options issued by RSL to RSL and RSI employees. (3) Share-Based Compensation for Family Members: In March 2015, Geetha Ramaswamy and Shankar Ramaswamy were granted stock options for 262,500 and 750,000 common shares of the Company, respectively, in each case with an exercise price of $ 0.90 per share. In September 2015, Sarah Friedhoff was granted stock options for 2,725 common shares of the Company. In April 2016, the Company granted Geetha Ramaswamy, Shankar Ramaswamy and Sarah Friedhoff stock options to purchase 43,000 common shares, 43,000 common shares and 10,000 common shares, respectively, as annual stock option grants in their capacities as employees of ASI. During the year ended March 31, 2018 , the Company granted Geetha Ramaswamy, Shankar Ramaswamy and Sarah Friedhoff stock options to purchase 37,500 common shares, 587,500 common shares and 12,500 common shares, respectively. Geetha Ramaswamy, MD and Sarah Friedhoff are no longer employed by ASI beginning in October 2017. The Company recorded aggregate share-based compensation expense of $4.0 million , $3.6 million and $3.4 million , respectively, for the years ended March 31, 2018 , 2017 and 2016 in connection with the Company's option grants. Shankar Ramaswamy, while previously employed by RSI, was also granted restricted stock in BVC. Following the BVC Merger, this restricted stock in BVC was converted into RSL common share awards, subject to vesting and forfeiture terms consistent with the original grant (See Note 8 (B) (2)). For the years ended March 31, 2018 , 2017 and 2016 , respectively, the Company recorded share-based compensation expense of $0.5 million , $0.5 million and $0.5 million related to the RSL common share awards held by Shankar Ramaswamy (inclusive of the compensation expense noted above for BVC awards prior to the BVC Merger on December 4, 2015), which the Company has recorded as research and development expense in the accompanying consolidated statements of operations. At March 31, 2018 , total unrecognized compensation expense related to these non-vested RSL common share awards was $0.1 million and is expected to be recognized over the remaining weighted average period of 0.27 years .

Income Taxes

Income Taxes	12 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The loss before income taxes and the related tax expense (benefit) are as follows (in thousands): Year ended March 31, 2018 Year ended March 31, 2017 Year ended March 31, 2016 Loss before income taxes: United States $ (13,039 ) $ (17,083 ) $ (13,955 ) Switzerland (197,765 ) (55,594 ) — Bermuda (9,697 ) (109,334 ) (119,207 ) Other 1 (151 ) — — Total loss before income taxes $ (220,652 ) $ (182,011 ) $ (133,162 ) Current taxes: United States $ (1,455 ) $ 1,270 $ 184 Switzerland — — — Bermuda — — — Other 1 (333 ) 56 122 Total current tax (benefit) expense (1,788 ) 1,326 306 Deferred taxes: United States 2,669 (2,361 ) (308 ) Switzerland — — — Bermuda — — — Other 1 40 (25 ) (15 ) Total deferred tax expense (benefit) 2,709 (2,386 ) (323 ) Total income tax expense (benefit) $ 921 $ (1,060 ) $ (17 ) 1 Primarily United States state and local and United Kingdom activity A reconciliation of income tax benefit computed at the Bermuda statutory rate to income tax expense (benefit) reflected in the financial statements is as follows (in thousands): Year Ended Year Ended Year Ended March 31, 2018 March 31, 2017 March 31, 2016 $ % $ % $ % Income tax benefit at Bermuda statutory rate $ — — % $ — — % $ — — % Foreign rate differential 1 (116,692 ) 52.88 (18,140 ) 9.96 (4,745 ) 3.56 Valuation allowance 113,070 (51.24 ) 18,607 (10.22 ) 5,194 (3.90 ) Tax reform implications 4,543 (2.06 ) — — — — Other — — (1,527 ) 0.84 (466 ) 0.35 Total income tax expense (benefit) $ 921 (0.42 )% $ (1,060 ) 0.58 % $ (17 ) 0.01 % 1 Related to current tax on United States operations including permanent and temporary difference (i.e. Research and Development credits), Switzerland net operating losses and United Kingdom taxation of the parent company. The Company's effective tax rate for the years ended March 31, 2018 , March 31, 2017 and March 31, 2016 was (0.42)% , 0.58% and 0.01% , respectively, driven by the Company's jurisdictional earnings by location and a valuation allowance that eliminates the Company's global net deferred tax assets. On December 22, 2017, the Tax Cuts and Jobs Act (the “Act”) was enacted, which introduced a comprehensive set of tax reforms in the United States. The Act revises the U.S. corporate income tax law by, among other things, lowering the corporate income tax rate from 35% to 21%, adopting a quasi-territorial income tax system, imposing a one-time transition tax on foreign unremitted earnings and setting limitations on deductibility of certain costs. The effects of changes in tax laws are required to be recognized in the period in which the legislation is enacted in accordance with ASC 740, Accounting for Income Taxes. However, due to the complexity and significance of the Act’s provisions, the SEC staff issued Staff Accounting Bulletin No. 118 (“SAB 118”), which allows companies to record the tax effects of the Act on a provisional basis based on a reasonable estimate, and then, if necessary, subsequently adjust such amounts during a limited measurement period as more information becomes available. The measurement period ends when a company has obtained, prepared, and analyzed the information necessary to finalize its accounting, but cannot extend beyond one year from enactment. The Act did not have a material impact on the Company's financial statements since its global net deferred tax assets are fully offset by a valuation allowance and the Company does not have any offshore earnings from which to record the mandatory transition tax. However, given the significant complexity of the Act, anticipated guidance from the U.S. Treasury about implementing the Act, and the potential for additional guidance from the SEC or the FASB related to the Act, these estimates may be adjusted during the measurement period. The provisional amounts for income taxes were based on the Company’s present interpretations of the Act and current available information, including assumptions and expectations about future events, such as its projected financial performance, and are subject to further refinement as additional information becomes available (including potential new or interpretative guidance issued by the FASB or the Internal Revenue Service and other tax agencies) and further analyses are completed. The provisional amount recorded related to the remeasurement of the Company’s deferred tax balances was $4.5 million which was offset fully by the provisional amount recorded related to the reversal of previously established valuation allowances against these deferred tax balances. The Act also permits any remaining AMT tax attribute carryforwards to be used to offset future taxable income and/or be refundable over the next several years. As a result, the Company recognized a provisional benefit of $0.1 million during the year ended March 31, 2018 related to the AMT tax credit carryforward. The related refundable amount has been classified in income tax receivable in the accompanying consolidated balance sheet. The Company continues to analyze the changes in certain income tax deductions and gather additional data to compute the full impacts on the Company’s current and deferred tax assets and liabilities (deferred tax assets and liabilities will be subject to a valuation allowance if adjusted). As of March 31, 2018 , the Company had an aggregate tax receivable of $1.8 million from various federal, state and local jurisdictions. Deferred taxes reflect the tax effects of the differences between the amounts recorded as assets and liabilities for financial reporting purposes and the comparable amounts recorded for income tax purposes. Significant components of the deferred tax assets (liabilities) at March 31, 2018 and 2017 are as follows (in thousands): March 31, 2018 March 31, 2017 Deferred tax assets: Research tax credits $ 8,757 $ 1,793 Other 293 937 Net operating loss 118,661 10,623 Share-based compensation 9,635 13,518 Subtotal 137,346 26,871 Valuation allowance (137,211 ) (24,141 ) Deferred tax liabilities: Depreciation (135 ) (21 ) Total deferred tax assets $ — $ 2,709 The Company has net operating losses in the United States, Switzerland and the United Kingdom in the amounts of $2.1 million , $1,063.8 million and $6.3 million , respectively. The United States federal NOL can be carried forward indefinitely with an annual limitation on utilization. The Switzerland NOL will begin to expire as of March 31, 2025. The UK NOL can be carried forward indefinitely with an annual limitation on utilization. In addition, the Company has United States research and development credit carryforwards in the amount of $8.8 million which will begin to expire as of March 31, 2026. The Company assesses the realizability of the deferred tax assets at each balance sheet date based on available positive and negative evidence in order to determine the amount which is more likely than not to be realized and record a valuation allowance as necessary. Due to the Company's cumulative loss position which provides significant negative evidence difficult to overcome, the Company has recorded a valuation allowance of $137.2 million as of March 31, 2018 , representing the portion of the deferred tax asset that is not more likely than not to be realized. The amount of the deferred tax asset considered realizable could be adjusted for future factors that would impact the assessment of the objective and subjective evidence of the Company. The Company will continue to assess the realizability of deferred tax assets at each balance sheet date in order to determine the proper amount, if any, required for a valuation allowance. There are outside basis differences related to the Company's investment in subsidiaries for which no deferred taxes have been recorded as these would not be subject to tax on repatriation as Bermuda has no tax regime for Bermuda exempted limited companies, and the UK tax regime relating to company distributions generally provides for exemption from tax for most overseas profits, subject to certain exceptions. The Company is subject to tax and will file income tax returns in the United Kingdom, Switzerland, and the United States federal and United States state and local jurisdictions. The Company is subject to tax examinations for tax years ended March 31, 2015 and forward in all applicable income tax jurisdictions. Tax audits and examinations can involve complex issues, interpretations and judgments. The resolution of matters may span multiple years particularly if subject to litigation or negotiation. The Company believes it has appropriately recorded its tax position using reasonable estimates and assumptions, however the potential tax benefits may impact the results of operations or cash flows in the period of resolution, settlement or when the statutes of limitations expire. There are no uncertain tax benefits recorded as of March 31, 2018.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Company has entered into commitments under a development, marketing and supply agreement with Arena (See Note 3 (A)), an amended Services Agreement with RSI (See Note 6 (A)), a separate services agreement with RSG (See Note 6 (A)), a license agreement with Qaam (See Note 3 (C)) and agreements with third parties for office space. In addition, the Company has entered into services agreements with third parties for pharmaceutical manufacturing and research activities. The manufacturing agreements can be terminated by the Company with 30 days written notice. The Company expects to enter into other commitments as its business further develops. In June 2017, the Company entered directly into a license agreement with a third party for approximately 19,554 square feet of office space in New York, New York. This license agreement will expire in January 2019. For the year ended March 31, 2018 , the Company incurred $1.2 million in rent expense under this license agreement. ASA is leasing 955 square feet of office space in Princeton, New Jersey under a lease agreement expiring in August 2020. During the year ended March 31, 2016, the Company entered into two subleases with RSI for office space in New York, NY. Under the terms of the subleases, RSI paid rent obligations directly pursuant to a master lease, and then invoiced the Company based on the Company's proportionate share of the space and overhead expenses, calculated based upon the relative numbers of full-time equivalent employees located on the premises. As a result, the Company's rent obligations were not fixed. For the years ended March 31, 2018 , 2017 and 2016 , the Company incurred $0.9 million , $1.2 million and $0.6 million , respectively, in rent expense under this arrangement with RSI. The Company ceased incurring rent expense under this arrangement with RSI after entering into the June 2017 license agreement for office space. As of March 31, 2018, the Company did not have any ongoing material financial commitments, other than pursuant to the Arena Development Agreement, Loan Agreement and agreements to rent office space. Under the terms of the asset purchase agreement with GSK, the Company made a $5.0 million milestone payment in June 2016, which had been recorded as a contingent payment liability as of March 31, 2016. The following table provides information with respect to contractual obligations as of March 31, 2018: Contractual Obligations (in thousands) Total Under 1 year 1-3 years 3-5 years Over 5 years Long-term debt obligations $ 55,000 $ 9,753 $ 45,247 $ — $ — Interest expense on long-term debt (1) 11,967 6,202 5,765 — — Rent obligations (2) 959 910 49 — — Total $ 67,926 $ 16,865 $ 51,061 $ — $ — (1) estimated using interest rate in effect at March 31, 2018 (2) net of prepayments

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Mar. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	Selected Quarterly Financial Data (Unaudited) The following table presents selected quarterly financial data for the years ended March 31, 2018 and March 31, 2017 : First Quarter Ended Second Quarter Ended Third Quarter Ended Fourth Quarter Ended First Quarter Ended Second Quarter Ended Third Quarter Ended Fourth Quarter Ended June 30, September 30, December 31, March 31, June 30, September 30, December 31, March 31, 2017 2017 2017 2018 2016 2016 2016 2017 Total operating expenses $65,230 $68,667 $55,378 $24,043 $37,907 $41,523 $47,972 $53,097 Net loss (69,266) (69,086) (57,902) (25,319) (38,055) (42,252) (47,811) (52,833) Net loss per share attributable to common shareholders - basic and diluted (0.65) (0.64) (0.54) (0.23) (0.38) (0.43) (0.48) (0.53)

Restructuring

Restructuring	12 Months Ended
	Mar. 31, 2018
Restructuring and Related Activities [Abstract]
Restructuring	Restructuring In October 2017, the Company initiated and committed to the first of two corporate realignments to focus its efforts and resources on the Company's ongoing and future programs that included a reduction in its workforce and a transfer of certain employees to affiliates. The second realignment was initiated and committed to in February 2018. As a result of the reduction in headcount, the Company incurred aggregate charges of approximately $ 6.0 million for one-time severance and related costs during the year ended March 31, 2018, all of which resulted from cash expenditures. The impacted employees are eligible to receive severance payments in specified amounts, health benefits and outplacement services. The Company has recorded these charges in research and development and general and administrative expenses in the accompanying consolidated statements of operations based on responsibilities of the impacted employees. Balance as of April 1, 2017 Expenses, net Cash Noncash Balance as of March 31, 2018 (in thousands) Employee severance and other personnel benefits $ — $ 6,035 $ (3,575 ) $ — $ 2,460

Subsequent Events

Subsequent Events	12 Months Ended
	Mar. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Oxford BioMedica License Agreement On June 5, 2018, ASG entered into the Oxford BioMedica Agreement with Oxford BioMedica, pursuant to which the Company received a worldwide, exclusive, royalty-bearing, sub-licensable license under certain patents and other intellectual property controlled by Oxford BioMedica to develop and commercialize OXB-102 (now AXO-Lenti-PD) and related gene therapy products for all diseases and conditions. As partial consideration for the license, the Company will make an upfront payment to Oxford BioMedica of $ 30.0 million , $ 5.0 million of which will be applied as a credit against the process development work and clinical supply that Oxford BioMedica will provide to the Company. Under the terms of the Oxford BioMedica Agreement, the Company could be obligated to make payments to Oxford BioMedica totaling up to $ 55.0 million upon the achievement of specified development milestones and $ 757.5 million upon the achievement of specified regulatory and sales milestones. The Company will also be obligated to pay Oxford BioMedica a tiered royalty from 7% to 10% , based on yearly aggregate net sales of the Gene Therapy Products, subject to specified reductions upon the occurrence of certain events as set forth in the Oxford BioMedica Agreement. These royalties are required to be paid, on a product-by-product and country-by-country basis, until the latest to occur of the expiration of the last to expire valid claim of a licensed patent covering such product in such country, the expiration of regulatory exclusivity for such product in such country, or 10 years after the first commercial sale of such product in such country. The Company is solely responsible, at its expense, for all activities related to the development and commercialization of the Gene Therapy Products. Pursuant to the Oxford BioMedica Agreement, the Company is required to use commercially reasonable efforts to develop, obtain regulatory approval of, and commercialize a Gene Therapy Product in the United States and at least one major market country in Europe. In addition, the Company is required to meet certain diligence milestones and to include at least one U.S.-based clinical trial site in a pivotal study of a Gene Therapy Product. If the Company fails to meet any of these specified development milestones, it may cure such failure by paying Oxford BioMedica certain fees, which range from $ 0.5 million to $ 1.0 million . Roivant Financing On June 5, 2018, the Company entered into a share purchase agreement (the “Purchase Agreement”) with RSL, our majority shareholder, pursuant to which the Company agreed to issue and sell to RSL 14,285,714 of its common shares at a purchase price of $ 1.75 per common share in a private placement (the “Private Placement”), equal to the per share closing price of the Company’s common shares on the Nasdaq Global Select Market on June 5, 2018. The Purchase Agreement includes customary representations, warranties and covenants. Closing of the Private Placement is subject to satisfaction or waiver of customary closing conditions, including the lapse of a 20 -day period following the mailing by the Company of an information statement relating to the Private Placement to its shareholders. As of March 31, 2018, RSL held 69.6% of the Company’s outstanding common shares. The aggregate gross proceeds to the Company from the Private Placement are expected to be approximately $ 25.0 million . The Company intends to use the net proceeds from the Private Placement to fund the clinical development of AXO-Lenti-PD as well as additional business development activities, for working capital and other general corporate purposes. The Company’s common shares issued and sold in the Private Placement will not be registered under the Securities Act or any state securities laws and may not be sold, offered for sale, pledged or hypothecated in the absence of a registration statement in effect with respect to the Company’s common shares under the Securities Act or an applicable exemption from the registration requirements. Amended and Restated Information Sharing and Cooperation Agreement On June 5, 2018, in connection with the Private Placement, the Company entered into an amended and restated information sharing and cooperation agreement (the “Restated Cooperation Agreement”) with RSL, which will become effective as of the closing date of the Private Placement. The Restated Cooperation Agreement, among other things: (1) obligates the Company to deliver to RSL periodic financial statements and other information upon reasonable request and to comply with other specified financial reporting requirements; (2) requires the Company to supply certain material information to RSL to assist it in preparing any future SEC filings; and (3) requires the Company to implement and observe certain policies and procedures related to applicable laws and regulations. The Company agreed to indemnify RSL and its affiliates and their respective officers, employees and directors against all losses arising out of, due to or in connection with RSL’s status as a shareholder under the Restated Cooperation Agreement and the operations of or services provided by RSL or its affiliates or their respective officers, employees or directors to the Company or any of its subsidiaries, subject to certain limitations set forth in the Restated Cooperation Agreement. Subject to specified exceptions, the Restated Cooperation Agreement will terminate at such time as RSL is no longer required (a) under U.S. GAAP to consolidate the Company's results of operations and financial position, (b) under U.S. GAAP to account for its investment in the Company under the equity method of accounting, or (c) otherwise to include separate financial statements of the Company in its filings with the SEC pursuant to any SEC rule. In addition, the Cooperation Agreement may be terminated upon mutual written consent of the parties or upon written notice from RSL to the Company in the event of the Company's bankruptcy, liquidation, dissolution or winding-up.

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation: The Company’s fiscal year ends on March 31, and its fiscal quarters end on June 30, September 30, and December 31. The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (‘‘ASC’’) and Accounting Standards Update (‘‘ASU’’) of the Financial Accounting Standards Board (‘‘FASB’’). The consolidated financial statements include the accounts of the Company and ASI, AHL and ASG, its wholly-owned subsidiaries. The Company has no unconsolidated subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Certain prior year amounts have been reclassified to conform with the current period presentation. These reclassifications had no effect on the previously reported results of operations.
Use of Estimates	Use of Estimates: The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. The Company regularly evaluates estimates and assumptions related to the assets, liabilities, costs and expenses (including compensation expense) allocated to the Company under its services agreements with Roivant Sciences, Inc. (“RSI”) and Roivant Sciences GmbH (“RSG”), each a wholly-owned subsidiary of the Company's majority shareholder, RSL, as well as contingent liabilities, share-based compensation and research and development costs. The Company bases its estimates and assumptions on historical experience and on various other factors that it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates.
Concentrations of Credit Risk	Concentrations of Credit Risk: Financial instruments that potentially subject the Company to concentration of credit risk include cash. At March 31, 2018, substantially all of the cash balances are deposited in four banking institutions and are all in excess of insured levels.
Property and Equipment	Property and Equipment: Property and equipment, consisting of leasehold improvements, furniture and fixtures, computers, software and other office equipment, is recorded at cost. Maintenance and repairs that do not improve or extend the lives of the respective assets are expensed to operations as incurred. Upon disposal, retirement or sale, the related cost and accumulated depreciation is removed from the accounts and any resulting gain or loss is included in the results of operations. Depreciation is recorded for property and equipment using the straight-line method over the estimated useful lives of the respective assets, generally three to five years, once the asset is installed and placed in service. Amortization of leasehold improvements is recorded over the shorter of the lease term or estimated useful life of the related asset. The Company reviews the recoverability of all long-lived assets, including the related useful lives, whenever events or changes in circumstances indicate that the carrying amount of a long-lived asset might not be recoverable. Recoverability is measured by comparison of the book values of the assets to future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceed their fair value, which is measured based on the projected discounted future net cash flows arising from the assets.
Debt Issuance Costs and Debt Discount	Debt Issuance Costs and Debt Discount: Debt issuance costs related to a recognized debt liability are presented on the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts, and are amortized to interest expense over the term of the related debt using the effective interest method. Further, debt discounts created as a result of the allocation of proceeds received from a debt issuance to warrants issued in conjunction with the debt issuance are amortized to interest expense under the effective interest method over the life of the recognized debt liability.
Research and Development Expense	Research and Development Expense: Research and development costs are expensed as incurred. Clinical study costs are accrued over the service periods specified in the contracts and adjusted as necessary based upon an ongoing review of the level of effort and costs actually incurred. Payments for a product license prior to regulatory approval of the product and payments for milestones achieved prior to regulatory approval of the product are expensed in the period incurred as research and development. Milestone payments made in connection with regulatory approvals are capitalized and amortized to cost of revenue over the remaining useful life of the asset. Research and development costs primarily consist of the intellectual property and research and development materials acquired from GlaxoSmithKline (“GSK”) and Arena Pharmaceuticals GmbH (“Arena”) (See Note 3), certain costs charged by RSI and RSG under their services agreements with the Company (See Note 6) and expenses from third parties who conduct research and development activities on behalf of the Company. The Company expenses in-process research and development projects acquired as asset acquisitions which have not reached technological feasibility and which have no alternative future use. For the years ended March 31, 2018 , 2017 and 2016 , the Company recorded $141.4 million , $134.8 million and $76.6 million , respectively, of research and development expense, of which $16.6 million , $19.2 million and $30.6 million , respectively, was attributable to share-based compensation expense.
Income Taxes	Income Taxes: Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and the respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance is recorded when, after consideration of all positive and negative evidence, it is not more likely than not that the Company's deferred tax assets will be realizable. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. When and if the Company were to recognize interest and penalties related to unrecognized tax benefits, they would be reported in tax expense in the consolidated statement of operations.
Share-Based Compensation	Share-Based Compensation: Share-based awards to employees and directors are valued at fair value on the date of grant and that fair value is recognized on a straight-line basis over the requisite service period of the entire award. The Company values its stock options using the Black-Scholes option pricing model. Certain assumptions need to be made with respect to utilizing the Black-Scholes option pricing model, including the expected life of the award, volatility of the underlying shares and the risk-free interest rate. The expected life of the stock options is calculated using the simplified method (based on the mid-point between the vesting date and the end of the contractual term). The risk-free interest rate is based on the rates paid on securities issued by the U.S. Treasury with a term approximating the expected life of the equity award. The expected share price volatility for the Company's common shares was estimated by taking the average historical price volatility for industry peers. As of April 1, 2017, the Company elected to change its policy from estimating forfeitures to recognizing forfeitures of awards when they occur (See Note 2(L)). Prior to this change, estimates of pre-vesting award forfeitures were based on the Company's expectations of future employee turnover and the Company adjusted its estimate of forfeitures over the requisite service period based on the extent to which actual forfeitures differed, or were expected to differ, from such estimates. Changes in estimated forfeitures were recognized through a cumulative catch-up adjustment in the period of change and impacted the amount of compensation expense to be recognized in future periods. The Company accounts for share-based payments to non-employees issued in exchange for services based upon the fair value of the equity instruments issued. Compensation expense for stock options issued to non-employees is calculated using the Black-Scholes option pricing model and is recorded over the service performance period. Options subject to vesting are required to be periodically remeasured over their service performance period, which is generally the same as the vesting period.
Net Loss per Common Share	Net Loss per Common Share: Basic net loss per common share is computed by dividing the net loss applicable to common shareholders by the weighted-average number of common shares outstanding during the year. Diluted net loss per common share is computed by dividing the net loss applicable to common shareholders by the diluted weighted-average number of common shares outstanding during the year calculated in accordance with the treasury stock method.
Financial Instruments	Financial Instruments: The Company utilizes fair value measurement guidance prescribed by accounting standards to value its financial instruments. The guidance establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company's own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company's assumptions about the inputs that market participants would use in pricing the asset or liability, and are developed based on the best information available in the circumstances. Fair value is identified as the exchange price, or exit price, representing the amount that would be received from the sale of an asset or paid to transfer a liability in an orderly transaction between market participants. As a basis for considering market participant assumptions in fair value measurements, the guidance establishes a three-tier fair value hierarchy that distinguishes among the following: • Level 1-Valuations are based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access. • Level 2-Valuations are based on quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active and models for which all significant inputs are observable, either directly or indirectly. • Level 3-Valuations are based on inputs that are unobservable (supported by little or no market activity) and significant to the overall fair value measurement. To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument's level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The Company's financial instruments include cash, accounts payable and debt. Cash and accounts payable are stated at their respective historical carrying amounts, which approximate fair value due to their short-term nature. Financial Instruments: The Company utilizes fair value measurement guidance prescribed by accounting standards to value its financial instruments. The guidance establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company's own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company's assumptions about the inputs that market participants would use in pricing the asset or liability, and are developed based on the best information available in the circumstances. Fair value is identified as the exchange price, or exit price, representing the amount that would be received from the sale of an asset or paid to transfer a liability in an orderly transaction between market participants. As a basis for considering market participant assumptions in fair value measurements, the guidance establishes a three-tier fair value hierarchy that distinguishes among the following: • Level 1-Valuations are based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access. • Level 2-Valuations are based on quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active and models for which all significant inputs are observable, either directly or indirectly. • Level 3-Valuations are based on inputs that are unobservable (supported by little or no market activity) and significant to the overall fair value measurement. To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument's level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The Company's financial instruments include cash, accounts payable and debt. Cash and accounts payable are stated at their respective historical carrying amounts, which approximate fair value due to their short-term nature.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements: In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842)” (“ASU No. 2016-02”), which is a comprehensive new lease standard that amends various aspects of existing accounting guidance for leases. The core principle of ASU No. 2016-02 will require lessees to present the assets and liabilities that arise from leases on their balance sheets. ASU No. 2016-02 is effective for annual periods beginning after December 15, 2018, and interim periods within fiscal years beginning after December 15, 2018. Early adoption is permitted. The Company is currently evaluating ASU No. 2016-02 and its impact on the Company's consolidated financial position and results of operations. In March 2016, the FASB issued ASU No. 2016-09, “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting” (“ASU No. 2016-09”). ASU No. 2016-09 makes several modifications to Topic 718 related to the accounting for forfeitures, employer tax withholding on share-based compensation, and the financial statement presentation of excess tax benefits or deficiencies. ASU No. 2016-09 also clarifies the statement of cash flows presentation for certain components of share-based awards. The Company adopted this guidance as of April 1, 2017, using a modified retrospective transition method. As a result of the adoption of ASU No. 2016-09, the Company elected to change its policy from estimating forfeitures to recognizing forfeitures when they occur and, as a result, recorded an adjustment of $ 235,000 to increase accumulated deficit with a corresponding offset to paid in capital as of April 1, 2017. The other requirements of ASU No. 2016-09 did not have a material impact on the Company's consolidated financial statements and related disclosures. In October 2016, the FASB issued ASU No. 2016-16, “ Intra-Entity Transfers of Assets Other Than Inventory ” (“ASU No. 2016-16”). ASU No. 2016-16 requires the income tax consequences of intra-entity transfers of assets other than inventory to be recognized as current period income tax expense or benefit and removes the requirement to defer and amortize the consolidated tax consequences of intra-entity transfers. The new standard will be effective for the Company on April 1, 2018 and will be adopted using a modified retrospective approach which requires a cumulative effect adjustment to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the new standard and its impact on the Company’s consolidated financial statements and related disclosures. In January 2017, the FASB issued ASU 2017-01, ‘‘ Business Combinations (Topic 805): Clarifying the Definition of a Business ’’ (‘‘ASU No. 2017-01’’), which clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. ASU No. 2017-01 is effective for annual reporting periods beginning after December 15, 2017, and interim periods within those years, with early adoption permitted. The Company will apply the guidance to applicable transactions after the adoption date. The impact on the Company’s consolidated financial statements will depend on the facts and circumstances of any specific future transactions. In May 2017, the FASB issued ASU No. 2017-09, “ Scope of Modification Accounting ” (‘‘ASU No. 2017-09’’). ASU No. 2017-09 clarifies which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. ASU No. 2017-09 is effective for interim and annual reporting periods beginning after December 15, 2017 and early adoption is permitted. The Company does not expect that this standard will have a material impact on the Company’s consolidated financial statements and related disclosures. In February 2018, the FASB issued ASU No. 2018-02, “ Income Statement-Reporting Comprehensive Income (Topic 220) : Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income ” (“ASU No. 2018-02”). ASU No. 2018-02 allows companies to reclassify stranded tax effects resulting from the Tax Cuts and Jobs Act, from accumulated other comprehensive (loss) income to retained earnings. ASU No. 2018-02 is effective for interim and annual reporting periods beginning after December 15, 2017 and early adoption is permitted. The Company is currently evaluating the new standard and its impact on the Company’s consolidated financial statements and related disclosures. In March 2018, the FASB issued ASU No. 2018-05, “ Income Taxes (Topic 740) : Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 ,” (“ASU No. 2018-05”). ASU No. 2018-05 amends certain SEC material in Topic 740 for the income tax accounting implications of the recently issued Tax Cuts and Jobs Act. ASU No. 2018-05 is effective immediately. The Company evaluated the impact of the Act as well as the guidance of Staff Accounting Bulletin 118 and incorporated the changes into the determination of a reasonable estimate of deferred taxes and appropriate disclosures in the notes to the Company’s consolidated financial statements. The Company will continue to evaluate the impact this tax reform legislation may have on our results of operations, financial position, cash flows and related disclosures.
Foreign Currency	Foreign Currency: The Company has operations in the United States, the United Kingdom and Switzerland. The results of its non-U.S. dollar based functional currency operations are translated to U.S. dollars at the average exchange rates during the year. The Company’s assets and liabilities are translated using the current exchange rate as of the balance sheet date and shareholders’ equity is translated using historical rates. Adjustments resulting from the translation of the financial statements of the Company’s foreign functional currency subsidiaries into U.S. dollars are excluded from the determination of net loss and are accumulated in a separate component of shareholders’ equity. Foreign exchange transaction gains and losses are included in other (income) expense in the Company’s results of operations.

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Mar. 31, 2018
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	As of March 31, 2018 and 2017 , accrued expenses consisted of the following (in thousands): March 31, 2018 March 31, 2017 Research and development expenses $ 21,855 $ 27,667 Salaries, bonuses, and other compensation expenses 7,718 3,497 Legal expenses 779 1,271 Other expenses 1,510 2,361 Total accrued expenses $ 31,862 $ 34,796

Long Term Debt (Tables)

Long Term Debt (Tables)	12 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Key Assumptions Used to Value Warrants	The key assumptions used to value the Warrant were as follows: Exercise price $ 12.04 Share price on date of issuance $ 11.96 Volatility 77.6 % Risk-free interest rate 2.27 % Expected dividend yield — % Contractual term (in years) 7
Outstanding Debt Obligations	Outstanding debt obligations are as follows (in thousands): March 31, 2018 March 31, 2017 Principal amount $ 55,000 $ 55,000 Less: unamortized discount and debt issuance costs (2,322 ) (3,564 ) Loan payable less unamortized discount and debt issuance costs 52,678 51,436 Less: current portion of long term debt (9,753 ) — Long-term loan payable, net of current maturities $ 42,925 $ 51,436

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Weighted Average Assumptions Used for Estimating the Fair Value of Stock Options	The Company estimated the fair value of each option on the date of grant using the Black-Scholes closed-form option-pricing model applying the weighted average assumptions in the following table: Years Ended March 31, 2018 2017 2016 Expected share price volatility 79.6 % 79.6 % 77.9 % Expected risk free interest rate 2.33 % 1.58 % 1.70 % Expected term, in years 6.50 6.30 6.58 Expected dividend yield — % — % — %
Schedule of Stock Option Activity	The following table presents a summary of option activity and data under the Company's stock incentive plans through March 31, 2018 : Number of Options Weighted Average Exercise Price Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Life Aggregate Intrinsic Value Options outstanding at March 31, 2015 4,012,500 $ 0.90 $ 14.30 9.96 $ 56,576,250 Granted 1,983,808 12.10 11.89 — — Exercised — — — — — Forfeited (102,725 ) 4.99 13.41 — — Cancelled — — — — — Options outstanding at March 31, 2016 5,893,583 $ 4.60 $ 13.50 9.11 $ 47,172,525 Granted 2,642,500 13.08 9.06 — — Exercised (13,919 ) 2.57 13.28 — 141,796 Forfeited (682,130 ) 4.26 12.86 — — Cancelled — — — — — Options outstanding at March 31, 2017 7,840,034 $ 7.49 $ 12.06 8.49 $ 61,104,445 Granted 17,192,085 10.14 6.94 Exercised (740,823 ) 2.13 13.85 13,002,098 Forfeited (10,206,160 ) 14.66 10.07 Cancelled — — — Options outstanding at March 31, 2018 14,085,136 $ 5.51 $ 6.59 8.73 $ 1,347,255 Options vested and expected to vest at March 31, 2018 14,085,136 $ 5.51 $ 6.59 8.73 $ 1,347,255 Options exercisable at March 31, 2018 11,042,482 $ 4.70 $ 6.59 8.64 $ 1,347,255

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	The loss before income taxes and the related tax expense (benefit) are as follows (in thousands): Year ended March 31, 2018 Year ended March 31, 2017 Year ended March 31, 2016 Loss before income taxes: United States $ (13,039 ) $ (17,083 ) $ (13,955 ) Switzerland (197,765 ) (55,594 ) — Bermuda (9,697 ) (109,334 ) (119,207 ) Other 1 (151 ) — — Total loss before income taxes $ (220,652 ) $ (182,011 ) $ (133,162 ) Current taxes: United States $ (1,455 ) $ 1,270 $ 184 Switzerland — — — Bermuda — — — Other 1 (333 ) 56 122 Total current tax (benefit) expense (1,788 ) 1,326 306 Deferred taxes: United States 2,669 (2,361 ) (308 ) Switzerland — — — Bermuda — — — Other 1 40 (25 ) (15 ) Total deferred tax expense (benefit) 2,709 (2,386 ) (323 ) Total income tax expense (benefit) $ 921 $ (1,060 ) $ (17 ) 1 Primarily United States state and local and United Kingdom activity
Reconciliation of Income Tax Benefit to Statutory Rate	A reconciliation of income tax benefit computed at the Bermuda statutory rate to income tax expense (benefit) reflected in the financial statements is as follows (in thousands): Year Ended Year Ended Year Ended March 31, 2018 March 31, 2017 March 31, 2016 $ % $ % $ % Income tax benefit at Bermuda statutory rate $ — — % $ — — % $ — — % Foreign rate differential 1 (116,692 ) 52.88 (18,140 ) 9.96 (4,745 ) 3.56 Valuation allowance 113,070 (51.24 ) 18,607 (10.22 ) 5,194 (3.90 ) Tax reform implications 4,543 (2.06 ) — — — — Other — — (1,527 ) 0.84 (466 ) 0.35 Total income tax expense (benefit) $ 921 (0.42 )% $ (1,060 ) 0.58 % $ (17 ) 0.01 % 1 Related to current tax on United States operations including permanent and temporary difference (i.e. Research and Development credits), Switzerland net operating losses and United Kingdom taxation of the parent company.
Schedule of Deferred Tax Assets and Liabilities	Significant components of the deferred tax assets (liabilities) at March 31, 2018 and 2017 are as follows (in thousands): March 31, 2018 March 31, 2017 Deferred tax assets: Research tax credits $ 8,757 $ 1,793 Other 293 937 Net operating loss 118,661 10,623 Share-based compensation 9,635 13,518 Subtotal 137,346 26,871 Valuation allowance (137,211 ) (24,141 ) Deferred tax liabilities: Depreciation (135 ) (21 ) Total deferred tax assets $ — $ 2,709

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contractual Obligations	The following table provides information with respect to contractual obligations as of March 31, 2018: Contractual Obligations (in thousands) Total Under 1 year 1-3 years 3-5 years Over 5 years Long-term debt obligations $ 55,000 $ 9,753 $ 45,247 $ — $ — Interest expense on long-term debt (1) 11,967 6,202 5,765 — — Rent obligations (2) 959 910 49 — — Total $ 67,926 $ 16,865 $ 51,061 $ — $ — (1) estimated using interest rate in effect at March 31, 2018 (2) net of prepayments

Selected Quarterly Financial 29

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Mar. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information	The following table presents selected quarterly financial data for the years ended March 31, 2018 and March 31, 2017 : First Quarter Ended Second Quarter Ended Third Quarter Ended Fourth Quarter Ended First Quarter Ended Second Quarter Ended Third Quarter Ended Fourth Quarter Ended June 30, September 30, December 31, March 31, June 30, September 30, December 31, March 31, 2017 2017 2017 2018 2016 2016 2016 2017 Total operating expenses $65,230 $68,667 $55,378 $24,043 $37,907 $41,523 $47,972 $53,097 Net loss (69,266) (69,086) (57,902) (25,319) (38,055) (42,252) (47,811) (52,833) Net loss per share attributable to common shareholders - basic and diluted (0.65) (0.64) (0.54) (0.23) (0.38) (0.43) (0.48) (0.53)

Restructuring (Tables)

Restructuring (Tables)	12 Months Ended
	Mar. 31, 2018
Restructuring and Related Activities [Abstract]
Schedule of Restructuring	Balance as of April 1, 2017 Expenses, net Cash Noncash Balance as of March 31, 2018 (in thousands) Employee severance and other personnel benefits $ — $ 6,035 $ (3,575 ) $ — $ 2,460

Description of Business (Detail

Description of Business (Details)	12 Months Ended
	Mar. 31, 2018segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments	1
Number of reporting segments	1

Summary of Significant Accoun32

Summary of Significant Accounting Policies - Concentration Risk (Details)	Mar. 31, 2018bank
Credit Concentration Risk
Concentration Risk [Line Items]
Number of banking institutions	4

Summary of Significant Accoun33

Summary of Significant Accounting Policies - Fixed Assets (Details)	12 Months Ended
	Mar. 31, 2018
Minimum
Property, Plant and Equipment [Line Items]
Useful life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Useful life	5 years

Summary of Significant Accoun34

Summary of Significant Accounting Policies - Research and Development Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Accounting Policies [Abstract]
Research and development expenses	$ 141,412	$ 134,778	$ 76,644
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation	$ 16,597	$ 19,186	$ 30,622

Summary of Significant Accoun35

Summary of Significant Accounting Policies - Net Loss per Common Share (Details) - shares shares in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Stock options and warrants
Net Loss per Common Share
Anti-dilutive securities not included in calculation of common shares outstanding (in shares)	14.1	8.1	5.9

Summary of Significant Accoun36

Summary of Significant Accounting Policies - Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Accounting Policies [Abstract]
Debt	$ 52,678	$ 51,436

Summary of Significant Accoun37

Summary of Significant Accounting Policies - Recently Issued Accounting Policies (Details) - Retained Earnings - USD ($) $ in Thousands	Apr. 01, 2017	Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment to adopt ASU 2016-09		$ 235
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment to adopt ASU 2016-09	$ 235

Asset Acquisitions (Details)

Asset Acquisitions (Details) - USD ($)	Oct. 28, 2015	Dec. 17, 2014	Aug. 31, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Asset Purchase Agreement
Research and development expenses				$ 141,412,000	$ 134,778,000	$ 76,644,000
License Agreement With Qaam Pharmaceuticals, LLC
Asset Purchase Agreement
Research and development expenses			$ 600,000
GSK | Asset Purchase Agreement | RVT-101 | Deferred payment payable
Asset Purchase Agreement
Research and development expenses		$ 5,000,000
RSL | RSL
Asset Purchase Agreement
Research and development expenses	$ 5,300,000
RSL | RSL | Information sharing and cooperation agreement, exercised waiver and option agreement
Asset Purchase Agreement
Related party transaction, agreement reimbursement percentage of option exercised	110.00%
Arena | Upon Achievement of Commercialization for Nelotanserin | Arena Development Agreement
Asset Purchase Agreement
Contingent payment liability				60,000,000
Arena | Development Expense | Arena Development Agreement
Asset Purchase Agreement
Contingent payment liability				4,000,000
Arena | Regulatory Expenses | Arena Development Agreement
Asset Purchase Agreement
Contingent payment liability				$ 37,500,000
Arena | Finished Drug Product | Arena Development Agreement
Asset Purchase Agreement
Contingent payment liability, as a percent of sales				15.00%
Arena | RSL
Asset Purchase Agreement
Research and development expenses	$ 4,000,000

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Payables and Accruals [Abstract]
Research and development expenses	$ 21,855	$ 27,667
Salaries, bonuses, and other compensation expenses	7,718	3,497
Legal expenses	779	1,271
Other expenses	1,510	2,361
Total accrued expenses	$ 31,862	$ 34,796

Long Term Debt (Details)

Long Term Debt (Details) - USD ($)	Feb. 02, 2017	Aug. 31, 2017	May 24, 2017
Debt Instrument [Line Items]
Exercise of warrant (in shares)		129,827
Common Shares
Debt Instrument [Line Items]
Number of shares for which warrants are exercisable (in shares)	274,086
Exercise price of warrants (in dollars per share)	$ 12.04
Fair value of warrants	$ 2,300,000
Term Loan | Loan and Security Agreement with Hercules Capital, Inc.
Debt Instrument [Line Items]
Amount borrowed	$ 55,000,000
Minimum unrestricted cash			$ 35,000,000
Minimum unrestricted cash if clinical milestones thresholds are met			$ 30,000,000
Interest rate in the event of debt default	5.00%
Maximum equity offering opportunity to be provided	$ 3,000,000
Loan term	48 months
Transaction costs	$ 1,500,000
Term Loan | Loan and Security Agreement with Hercules Capital, Inc. | Minimum
Debt Instrument [Line Items]
Fixed interest rate	10.55%
Term Loan | Loan and Security Agreement with Hercules Capital, Inc. | Prime Rate
Debt Instrument [Line Items]
Variable interest rate	6.80%

Long Term Debt - Fair Value Ass

Long Term Debt - Fair Value Assumptions for Warrants (Details) - Common Shares	Feb. 02, 2017$ / shares
Class of Warrant or Right [Line Items]
Exercise price (in dollars per share)	$ 12.04
Share price on date of issuance (in shares)	$ 11.96
Volatility	77.60%
Risk-free interest rate	2.27%
Expected dividend yield	0.00%
Contractual term (in years)	7 years

Long Term Debt - Outstanding De

Long Term Debt - Outstanding Debt Obligations (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Debt Disclosure [Abstract]
Principal amount	$ 55,000	$ 55,000
Less: unamortized discount and debt issuance costs	(2,322)	(3,564)
Loan payable less unamortized discount and debt issuance costs	52,678	51,436
Less: current portion of long term debt	(9,753)	0
Long-term loan payable, net of current maturities	$ 42,925	$ 51,436

Related Party Transactions (Det

Related Party Transactions (Details)	12 Months Ended
	Mar. 31, 2018USD ($)investor	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)
Related Party Transaction [Line Items]
Number of investors who provided compensation expense to parent company's CEO | investor	1
RSI
Related Party Transaction [Line Items]
Expense under service agreement	$ 8,500,000	$ 7,900,000	$ 7,600,000
RSI | Chief Executive Officer
Related Party Transaction [Line Items]
Share-based compensation	0	41,000	1,000,000
Shankar Ramaswamy | Family Relationships
Related Party Transaction [Line Items]
Salary expenses	267,800	259,167	239,583
Geetha Ramaswamy | Family Relationships
Related Party Transaction [Line Items]
Salary expenses	133,900	259,167	239,583
Sarah Friedhoff | Family Relationships
Related Party Transaction [Line Items]
Salary expenses	$ 38,625	$ 74,167	$ 42,709

Shareholders' Equity (Details)

Shareholders' Equity (Details) $ / shares in Units, $ in Thousands	Jun. 16, 2015USD ($)$ / sharesshares	Mar. 18, 2015$ / sharesshares	Dec. 17, 2014USD ($)shares	Apr. 30, 2017USD ($)$ / sharesshares	Apr. 30, 2015USD ($)shares	Mar. 31, 2015shares	Mar. 31, 2018USD ($)$ / sharesshares	Mar. 31, 2017USD ($)$ / sharesshares	Mar. 31, 2016USD ($)shares	Mar. 19, 2015$ / sharesshares	Oct. 31, 2014class$ / sharesshares
Shareholders' Equity
Number of classes of stock authorized | class											1
Common shares authorized (in shares)		10,000					1,000,000,000	1,000,000,000		1,000,000,000	10,000
Common shares par value (in dollars per share) | $ / shares		$ 1					$ 0.00001	$ 0.00001		$ 0.00001	$ 1
Common stock issued during period (in shares)		650				65,000,000
Common stock issued (in shares)		750				75,000,000	107,788,074	99,163,919		75,000,000
Common shares outstanding (in shares)		750					107,788,074	99,163,919	75,000,000
Stock split ratio		100,000
Capital contribution | $							$ 324	$ 0	$ 751
Gross proceeds from IPO | $	$ 362,300
Net proceeds from IPO, net of underwriting discounts and commissions and offering expenses | $	334,500
Underwriting discounts, commissions and offering expenses | $	$ 27,700						9,200		$ 27,748
IPO
Shareholders' Equity
Common stock issued during period (in shares)	24,150,000
Common stock issued (in dollars per share) | $ / shares	$ 15
Stock Offering
Shareholders' Equity
Common stock issued during period (in shares)				7,753,505
Common stock issued (in dollars per share) | $ / shares				$ 18.54
Gross proceeds from common stock issued | $				$ 143,700
Net proceeds from common stock issued | $				$ 134,500
Underwriter's Option
Shareholders' Equity
Common stock issued during period (in shares)	3,150,000			1,011,326
RSL
Shareholders' Equity
Common stock, shares subscribed (in shares)											100
Additional shares issued (in shares)			0		0
Percentage ownership of stock			100.00%
Capital contribution | $					$ 800		$ 300
RSL | GSK | Asset Purchase Agreement | RVT-101
Shareholders' Equity
Capital contribution | $			$ 5,000

Share-Based Compensation - Nar

Share-Based Compensation - Narrative (Details) $ / shares in Units, $ in Millions	Mar. 01, 2018USD ($)individual$ / sharesshares	Apr. 13, 2015$ / shares	Apr. 30, 2016shares	Sep. 30, 2015shares	Apr. 30, 2015$ / sharesshares	Mar. 31, 2015$ / sharesshares	Mar. 31, 2018USD ($)$ / sharesshares	Mar. 31, 2017USD ($)$ / sharesshares	Mar. 31, 2016USD ($)$ / sharesshares	Jun. 30, 2017shares	Apr. 01, 2017shares	Apr. 01, 2016shares	May 31, 2015shares
Share-Based Compensation
Number of options granted (in shares)							17,192,085	2,642,500	1,983,808
Fair value of the common shares (in dollars per share) | $ / shares		$ 15			$ 1.04	$ 0.90
Exercise price of options (in dollars per share) | $ / shares						$ 0.90	$ 5.51	$ 7.49	$ 4.60
Number of options vested (in shares)							3,600,000
Options granted, weighted average exercise price (in dollars per share) | $ / shares							$ 10.14	$ 13.08	$ 12.10
Employee and Nonemployee Stock Option, Repriced [Member]
Share-Based Compensation
Number of options repriced (in shares)	1,264,085
Number of individuals holding repriced options | individual	51
Exercise price of options (in dollars per share) | $ / shares	$ 1.49
Share-based compensation expense | $	$ 0.1
Number of options vested (in shares)	146,370
Number of non-vested options (in shares)	1,117,715
Unrecognized compensation expense related to options | $	$ 0.5
RSL
Share-Based Compensation
Share-based compensation expense | $							$ 5.4	$ 10.9	$ 53.4
RSL | Common Share Awards
Share-Based Compensation
Remaining weighted-average service period							3 months 7 days
Unrecognized compensation expense related to common share awards | $							$ 0.1
2015 Plan
Share-Based Compensation
Number of shares reserved for grant (in shares)						7,500,000				20,500,000	16,500,000	12,500,000	9,500,000
Number of options granted (in shares)					527,500	4,012,500
Number of shares available for future issuance (in shares)							5,600,000
Directors and Employees
Share-Based Compensation
Number of options granted (in shares)							16,100,000	2,600,000	1,800,000
Share-based compensation expense | $							$ 21	$ 23.1	$ 16.3
Unrecognized compensation expense related to options | $							$ 39.4
Options granted, weighted average exercise price (in dollars per share) | $ / shares							$ 9.56	$ 13.09	$ 11.96
Remaining weighted-average service period							2 years 6 months 7 days
Consultants and Employees | Employee and Nonemployee Stock Option
Share-Based Compensation
Award vesting period							4 years
Award contractual term							10 years
Director | Employee and Nonemployee Stock Option
Share-Based Compensation
Award vesting period							3 years
Award contractual term							10 years
Employees of RSI
Share-Based Compensation
Number of options granted (in shares)							1,046,600	86,700	215,000
Share-based compensation expense | $							$ 4.8	$ 1.6	$ 1.1
Unrecognized compensation expense related to options | $							$ 1.1
Remaining weighted-average service period							2 years 6 months 18 days
Geetha Ramaswamy
Share-Based Compensation
Number of options granted (in shares)			43,000			262,500	37,500
Options granted, weighted average exercise price (in dollars per share) | $ / shares						$ 0.90
Shankar Ramaswamy
Share-Based Compensation
Number of options granted (in shares)			43,000			750,000	587,500
Options granted, weighted average exercise price (in dollars per share) | $ / shares						$ 0.90
Shankar Ramaswamy | RSL | Common Share Awards
Share-Based Compensation
Share-based compensation expense | $							$ 0.5	0.5	0.5
Sarah Friedhoff
Share-Based Compensation
Number of options granted (in shares)			10,000	2,725			12,500
Geetha Ramaswamy, Shankar Ramaswamy and Sarah Friedhoff
Share-Based Compensation
Share-based compensation expense | $							$ 4	$ 3.6	$ 3.4

Share-Based Compensation - Stoc

Share-Based Compensation - Stock Option, Fair Value Assumptions (Details)	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Expected share price volatility	79.60%	79.60%	77.90%
Expected risk free interest rate	2.33%	1.58%	1.70%
Expected term, in years	6 years 6 months	6 years 3 months 18 days	6 years 6 months 29 days
Expected dividend yield	0.00076%	0.00%	0.00%

Share-Based Compensation - St47

Share-Based Compensation - Stock Option Activity (Details) - USD ($)	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Number of Options
Beginning balance (in shares)	7,840,034	5,893,583	4,012,500
Granted (in shares)	17,192,085	2,642,500	1,983,808
Exercised (in shares)	(740,823)	(13,919)	0
Forfeited (in shares)	(10,206,160)	(682,130)	(102,725)
Cancelled (in shares)	0	0	0
Ending balance (in shares)	14,085,136	7,840,034	5,893,583	4,012,500
Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 7.49	$ 4.60	$ 0.90
Granted (in dollars per share)	10.14	13.08	12.10
Exercised (in dollars per share)	2.13	2.57	0
Forfeited (in dollars per share)	14.66	4.26	4.99
Cancelled (in dollars per share)	0	0	0
Ending balance (in dollars per share)	5.51	7.49	4.60	$ 0.90
Weighted Average Grant Date Fair Value
Beginning balance (in dollars per share)	12.06	13.50	14.30
Granted (in dollars per share)	6.94	9.06	11.89
Exercised (in dollars per share)	13.85	13.28	0
Forfeited (in dollars per share)	10.07	12.86	13.41
Cancelled (in dollars per share)	0	0	0
Ending balance (in dollars per share)	$ 6.59	$ 12.06	$ 13.50	$ 14.30
Additional Disclosures
Options outstanding, weighted average contractual term	8 years 8 months 23 days	8 years 5 months 27 days	9 years 1 month 10 days	9 years 11 months 16 days
Options outstanding, aggregate intrinsic value	$ 1,347,255	$ 61,104,445	$ 47,172,525	$ 56,576,250
Options granted, aggregate intrinsic value	$ 13,002,098	$ 141,796	$ 0
Options exercisable, number of options (in shares)	11,042,482
Options exercisable, weighted average exercise price (in dollars per share)	$ 4.70
Options exercisable, weighted average grant date fair value (in dollars per share)	$ 6.59
Options exercisable, weighted average contractual term	8 years 7 months 21 days
Options exercisable, aggregate intrinsic value	$ 1,347,255
Options Vested and Expected to Vest
Number of Options (in shares)	14,085,136
Weighted Average Exercise Price (in dollars per share)	$ 5.51
Weighted Average Grant Date Fair Value (in dollars per share)	$ 6.59
Weighted Average Remaining Contractual Life	8 years 8 months 23 days
Aggregate Intrinsic Value	$ 1,347,255

Income Taxes- Summary of Income

Income Taxes- Summary of Income Tax Expense by Jurisdiction (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Loss before income taxes:
Bermuda	$ (9,697)	$ (109,334)	$ (119,207)
Total loss before income taxes	(220,652)	(182,011)	(133,162)
Current taxes:
Bermuda	0	0	0
Total current tax (benefit) expense	(1,788)	1,326	306
Deferred taxes:
Bermuda	0	0	0
Total deferred tax expense (benefit)	2,709	(2,386)	(323)
Total income tax expense (benefit)	921	(1,060)	(17)
United States
Loss before income taxes:
Foreign	(13,039)	(17,083)	(13,955)
Current taxes:
Foreign	(1,455)	1,270	184
Deferred taxes:
Foreign	2,669	(2,361)	(308)
Switzerland
Loss before income taxes:
Foreign	(197,765)	(55,594)
Current taxes:
Foreign	0	0	0
Deferred taxes:
Foreign	0	0	0
Other
Loss before income taxes:
Foreign	(151)	0	0
Current taxes:
Foreign	(333)	56	122
Deferred taxes:
Foreign	$ 40	$ (25)	$ (15)

Income Taxes Income Taxes - Rec

Income Taxes Income Taxes - Reconciliation of Income Tax Benefit to Statutory Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
$
Income tax benefit at Bermuda statutory rate	$ 0	$ 0	$ 0
Foreign rate differential	(116,692)	(18,140)	(4,745)
Valuation allowance	113,070	18,607	5,194
Tax reform implications	4,543	0	0
Other	0	(1,527)	(466)
Total income tax expense (benefit)	$ 921	$ (1,060)	$ (17)
%
Income tax benefit at Bermuda statutory rate	0.00%	0.00%	0.00%
Foreign rate differential	52.88%	9.96%	3.56%
Valuation allowance	(51.24%)	(10.22%)	(3.90%)
Tax reform implications	(2.06%)	0.00%	0.00%
Other	0.00%	0.84%	0.35%
Total income tax expense (benefit)	(0.42%)	0.58%	0.01%

Income Taxes- Narrative (Detail

Income Taxes- Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Operating Loss Carryforwards [Line Items]
Effective income tax rate	(0.42%)	0.58%	0.01%
Provisional income tax expense related to remeasurement of deferred tax balances	$ 4,500
Provisional income tax benefit related to AMT tax credit carryforward	100
Income tax receivable	1,751	$ 658
Valuation allowance on deferred tax assets	137,211	$ 24,141
United States
Operating Loss Carryforwards [Line Items]
Net operating losses	2,100
Switzerland
Operating Loss Carryforwards [Line Items]
Net operating losses	1,063,800
United Kingdom
Operating Loss Carryforwards [Line Items]
Net operating losses	6,300
Research and Development Tax Credit Carryforward | United States
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 8,800

Income Taxes- Schedule of Defer

Income Taxes- Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Deferred tax assets:
Research tax credits	$ 8,757	$ 1,793
Other	293	937
Net operating loss	118,661	10,623
Share-based compensation	9,635	13,518
Subtotal	137,346	26,871
Valuation allowance	(137,211)	(24,141)
Deferred tax liabilities:
Depreciation	(135)	(21)
Total deferred tax assets	$ 0	$ 2,709

Commitments and Contingencies52

Commitments and Contingencies (Details) $ in Millions	12 Months Ended
	Mar. 31, 2018USD ($)ft²	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)agreement	Jun. 30, 2017ft²
GSK
Other Commitments [Line Items]
Minimum notice period required to terminate contract	30 days
Contingent payment liability	$ 5
Third Party
Other Commitments [Line Items]
Area leased (in sq ft) | ft²				19,554
Rent expense	$ 1.2
Area subleased (in sq ft) | ft²	955
RSI
Other Commitments [Line Items]
Number of sublease agreements | agreement			2
Rent expense	$ 0.9	$ 1.2	$ 0.6

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Contractual Obligations (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Long-term debt obligations
Total	$ 55,000	$ 55,000
Under 1 year	9,753
1-3 years	45,247
3-5 years	0
Over 5 years	0
Interest expense on long-term debt
Total	11,967
Under 1 year	6,202
1-3 years	5,765
3-5 years	0
Over 5 years	0
Rent obligations
Total	959
Under 1 year	910
1-3 years	49
3-5 years	0
Over 5 years	0
Total
Total	67,926
Under 1 year	16,865
1-3 years	51,061
3-5 years	0
Over 5 years	$ 0

Selected Quarterly Financial 54

Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Total operating expenses	$ 24,043	$ 55,378	$ 68,667	$ 65,230	$ 53,097	$ 47,972	$ 41,523	$ 37,907	$ 213,318	$ 180,499	$ 133,162
Net loss	$ (25,319)	$ (57,902)	$ (69,086)	$ (69,266)	$ (52,833)	$ (47,811)	$ (42,252)	$ (38,055)	$ (221,573)	$ (180,951)	$ (133,145)
Net loss per share attributable to common stockholders — basic and diluted (in dollars per share)	$ (0.23)	$ (0.54)	$ (0.64)	$ (0.65)	$ (0.53)	$ (0.48)	$ (0.43)	$ (0.38)	$ (2.06)	$ (1.82)	$ (1.41)

Restructuring (Details)

Restructuring (Details) $ in Thousands	12 Months Ended
	Mar. 31, 2018USD ($)
Restructuring Reserve [Roll Forward]
Balance as of April 1, 2017	$ 0
Expenses, net	6,035
Cash	(3,575)
Noncash	0
Balance as of March 31, 2018	$ 2,460

Subsequent Events (Details)

Subsequent Events (Details) - USD ($)	Jun. 05, 2018	Apr. 02, 2018	Apr. 30, 2018	Mar. 31, 2018	Mar. 31, 2016
Subsequent Event [Line Items]
Price of shares issued and sold (in dollars per share)					$ 15
RSL
Subsequent Event [Line Items]
Ownership percentage				69.60%
Subsequent Event | Private Placement | RSL
Subsequent Event [Line Items]
Number of shares issued and sold (in shares)		14,285,714
Price of shares issued and sold (in dollars per share)		$ 1.75
Customary closing conditions term		20 days
Aggregate gross proceeds from shares issued and sold			$ 25,000,000
Subsequent Event | Oxford BioMedica
Subsequent Event [Line Items]
Upfront payment for license agreement	$ 30,000,000
Upfront payment for license agreement applied as a credit against the process development work and clinical supply	5,000,000
Maximum obligation under license agreement upon achievement of developmental milestones	55,000,000
Maximum obligation under license agreement upon achievement of regulatory and sales milestones	$ 757,500,000
License agreement term after first commercial sale	10 years
Subsequent Event | Oxford BioMedica | Minimum
Subsequent Event [Line Items]
Tiered royalty percentage under license agreement	7.00%
Fees under license agreement if developmental milestones are not met	$ 500,000
Subsequent Event | Oxford BioMedica | Maximum
Subsequent Event [Line Items]
Tiered royalty percentage under license agreement	10.00%
Fees under license agreement if developmental milestones are not met	$ 1,000,000