Wave Life Sciences (WVE) 10-Q 9 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	May 01, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Trading Symbol	WVE
Entity Registrant Name	WAVE LIFE SCIENCES LTD.
Entity Central Index Key	1,631,574
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		29,105,452

Unaudited Consolidated Balance

Unaudited Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 110,491	$ 142,503
Prepaid expenses and other current assets	7,470	7,985
Total current assets	117,961	150,488
Long-term assets:
Property and equipment, net	28,778	27,334
Restricted cash	3,612	3,610
Other assets	70	411
Total long-term assets	32,460	31,355
Total assets	150,421	181,843
Current liabilities:
Accounts payable	8,014	7,598
Accrued expenses and other current liabilities	6,461	8,898
Current portion of capital lease obligation		16
Current portion of deferred rent	70	60
Current portion of deferred revenue	1,275	1,275
Current portion of lease incentive obligation	478	344
Total current liabilities	16,298	18,191
Long-term liabilities:
Deferred rent, net of current portion	4,591	4,214
Deferred revenue, net of current portion	5,819	7,241
Lease incentive obligation, net of current portion	4,185	3,094
Other liabilities	1,605	1,619
Total long-term liabilities	16,200	16,168
Total liabilities	32,498	34,359
Series A preferred shares, no par value; 3,901,348 shares issued and outstanding at March 31, 2018 and December 31, 2017	7,874	7,874
Shareholders’ equity:
Ordinary shares, no par value; 27,993,337 and 27,829,079 shares issued and outstanding at March 31, 2018 and December 31, 2017, respectively	311,591	310,038
Additional paid-in capital	26,602	22,172
Accumulated other comprehensive income	165	116
Accumulated deficit	(228,309)	(192,716)
Total shareholders’ equity	110,049	139,610
Total liabilities, Series A preferred shares and shareholders’ equity	$ 150,421	$ 181,843

Unaudited Consolidated Balance3

Unaudited Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Series A preferred stock, par value	$ 0	$ 0
Series A preferred stock, shares issued	3,901,348	3,901,348
Series A preferred stock, shares outstanding	3,901,348	3,901,348
Common stock, par value	$ 0	$ 0
Common stock, shares issued	27,993,337	27,829,079
Common stock, shares outstanding	27,993,337	27,829,079

Unaudited Consolidated Statemen

Unaudited Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Revenue	$ 1,422	$ 383
Operating expenses:
Research and development	29,196	14,740
General and administrative	8,001	5,850
Total operating expenses	37,197	20,590
Loss from operations	(35,775)	(20,207)
Other income (expense), net:
Dividend income	356	290
Interest income (expense), net	7	3
Other income (expense), net	343	(72)
Total other income (expense), net	706	221
Loss before income taxes	(35,069)	(19,986)
Income tax provision	(172)	(1,110)
Net loss	$ (35,241)	$ (21,096)
Net loss per share attributable to ordinary shareholders—basic and diluted	$ (1.26)	$ (0.90)
Weighted-average ordinary shares used in computing net loss per share attributable to ordinary shareholders—basic and diluted	27,919,063	23,531,788
Other comprehensive income (loss):
Foreign currency translation	$ 49	$ 15
Comprehensive loss	$ (35,192)	$ (21,081)

Unaudited Consolidated Stateme5

Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Net loss	$ (35,241)	$ (21,096)
Adjustments to reconcile net loss to net cash used in operating activities:
Amortization of lease incentive obligation	(107)	(17)
Depreciation of property and equipment	1,175	315
Share-based compensation expense	4,430	2,999
Loss on disposal of property and equipment	13
Deferred rent	387	1,031
Deferred income taxes		(193)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	515	(1,813)
Other non-current assets	(11)
Accounts payable	390	1,017
Accrued expenses and other current liabilities	(2,541)	(537)
Deferred revenue	(1,422)	(383)
Other non-current liabilities	(14)	1,259
Net cash used in operating activities	(32,426)	(17,418)
Cash flows from investing activities
Purchases of property and equipment	(1,164)	(3,635)
Net cash used in investing activities	(1,164)	(3,635)
Cash flows from financing activities
Payments on capital lease obligation	(16)	(16)
Proceeds from the exercise of share options	1,553	206
Net cash provided by financing activities	1,537	190
Effect of foreign exchange rates on cash, cash equivalents and restricted cash	43	57
Net decrease in cash, cash equivalents and restricted cash	(32,010)	(20,806)
Cash, cash equivalents and restricted cash, beginning of period	146,113	153,894
Cash, cash equivalents and restricted cash, end of period	114,103	133,088
Supplemental disclosure of cash flow information:
Cash paid for taxes, net of refunds	314	18
Property and equipment purchases in accounts payable and accrued expenses at period end	469	2,976
Tenant improvements paid for by the landlord during the period	800	$ 1,082
Tenant improvements to be reimbursed by the landlord	$ 1,279

The Company

The Company	3 Months Ended
	Mar. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
The Company	1. THE COMPANY Organization Wave Life Sciences Ltd. (together with its subsidiaries, “Wave” or the “Company”) is a biotechnology company with an innovative and proprietary synthetic chemistry drug development platform that the Company is using to rationally design, develop and commercialize a broad pipeline of first-in-class or best-in-class nucleic acid therapeutic candidates for genetically defined diseases. Nucleic acid therapeutics are a growing and innovative class of drugs that have the potential to address diseases that have historically been difficult to treat with small molecule drugs or biologics. Nucleic acid therapeutics, or oligonucleotides, are comprised of a sequence of nucleotides that are linked together by a backbone of chemical bonds. The Company is initially developing oligonucleotides that target genetic defects to either reduce the expression of disease-promoting proteins or transform the production of dysfunctional mutant proteins into the production of functional proteins. The Company was incorporated in Singapore on July 23, 2012 and has its principal U.S. office in Cambridge, Massachusetts. The Company was incorporated with the purpose of combining two commonly held companies, Wave Life Sciences USA, Inc. (“Wave USA”), a Delaware corporation (formerly Ontorii, Inc.), and Wave Life Sciences Japan, Inc. (“Wave Japan”), a company organized under the laws of Japan (formerly Chiralgen., Ltd.), which occurred on September 13, 2012. On May 31, 2016, Wave Life Sciences Ireland Limited (“Wave Ireland”) was formed as a wholly - - The Company’s primary activities since inception have been developing an innovative and proprietary synthetic chemistry drug development platform to design, develop and commercialize nucleic acid therapeutic programs, advancing the Company’s neurology franchise, expanding the Company’s research and development activities into additional therapeutic areas including ophthalmology and hepatic, advancing programs into the clinic, furthering clinical development of such clinical-stage programs, building the Company’s intellectual property, recruiting personnel and assuring adequate capital to support these activities. Risks and Uncertainties The Company is subject to risks common to companies in the biotechnology industry including, but not limited to, new technological innovations, protection of proprietary technology, establishment of internal manufacturing capabilities, dependence on key personnel, compliance with government regulations and the need to obtain additional financing. The Company’s therapeutic programs will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval, prior to commercialization of any product candidates. These efforts require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance-reporting capabilities. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained, that any products developed will obtain necessary government regulatory approval or that any approved products will be commercially viable. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its employees and consultants. The Company has never been profitable, and since its inception has incurred recurring operating losses. The Company expects to incur significant expenses and increasing operating losses for the foreseeable future. To date, the Company has primarily funded its operations through private placements of debt and equity securities, public offerings of its ordinary shares and upfront payments and equity investments related to collaborations with third parties. As of March 31, 2018, the Company has received an aggregate of approximately $323.2 million in net proceeds from these transactions. The Company received $89.3 million in net proceeds from private placements of its debt and equity securities, $100.4 million in net proceeds from its initial public offering, inclusive of the over-allotment exercise, $40.0 million of upfront payments under the Pfizer Agreements (as defined in Note 4), including $10.0 million as an upfront payment under the Pfizer Collaboration Agreement (as defined in Note 4) and $30.0 million in the form of an equity investment, and $93.5 million in net proceeds from its April 2017 follow-on underwritten public offering. Basis of Presentation The Company has prepared the accompanying consolidated financial statements in conformity with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and in U.S. dollars.

Significant Accounting Policies

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	2. SIGNIFICANT ACCOUNTING POLICIES The significant accounting policies described in the Company’s audited financial statements as of and for the year ended December 31, 2017, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the Securities and Exchange Commission (“SEC”) on March 12, 2018, as amended (the “2017 Annual Report on Form 10-K”), other than the Company’s adoption of ASC 606 (as defined below) which is discussed in detail in Unaudited Interim Financial Data The accompanying interim consolidated balance sheet as of March 31, 2018, the related interim consolidated statements of operations and comprehensive loss for the three months ended March 31, 2018 and 2017 and cash flows for the three months ended March 31, 2018 and 2017, and the related interim information contained within the notes to the consolidated financial statements have been prepared in accordance with the rules and regulations of the SEC for interim financial information. Accordingly, they do not include all of the information and the notes required by U.S. GAAP for complete financial statements. The financial data and other information disclosed in these notes related to the three months ended March 31, 2018 and 2017 are unaudited. In the opinion of management, the unaudited interim consolidated financial statements reflect all adjustments, consisting of normal and recurring adjustments, necessary for the fair presentation of the Company’s financial position and results of operations for the three months ended March 31, 2018 and 2017. The results of operations for the interim periods are not necessarily indicative of the results to be expected for the year ending December 31, 2018 or any other interim period or future year or period. Principles of Consolidation The Company’s consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. Revenue Recognition Effective January 1, 2018, the Company adopted Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“ASC 606”), using the full retrospective transition method. Under this method, the Company revised its consolidated financial statements for the years ended December 31, 2017 and 2016, and applicable interim periods within those years, as if ASC 606 had been effective for those periods. This standard applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, and financial instruments. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, the entity performs the following five-step analysis: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step analysis to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract, determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. The Company has entered into collaboration agreements for research, development, and commercial services, under which the Company licenses certain rights to its product candidates to third parties. The terms of these arrangements typically include payment to the Company of one or more of the following: non-refundable, upfront license fees; reimbursement of certain costs; customer option exercise fees; development, regulatory and commercial milestone payments; and royalties on net sales of licensed products. Any variable consideration is constrained, and therefore, the cumulative revenue associated with this consideration is not recognized until it is deemed not to be at significant risk of reversal. In determining the appropriate amount of revenue to be recognized as the Company fulfills its obligations under each of its agreements for which the collaboration partner is also a customer, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. As part of the accounting for these arrangements, the Company must use significant judgment to determine: (a) the number of performance obligations based on the determination under step (ii) above; (b) the transaction price under step (iii) above; and (c) the timing of satisfaction of performance obligations as a measure of progress in step (v) above. The Company uses significant judgment to determine whether milestones or other variable consideration, except for royalties, should be included in the transaction price as described further below. Amounts received prior to revenue recognition are recorded as deferred revenue. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current portion of deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. Licenses of intellectual property: In assessing whether a promise or performance obligation is distinct from the other promises, the Company considers factors such as the research, development, manufacturing and commercialization capabilities of the customer and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the customer can benefit from a promise for its intended purpose without the receipt of the remaining promise, whether the value of the promise is dependent on the unsatisfied promise, whether there are other vendors that could provide the remaining promise, and whether it is separately identifiable from the remaining promise. For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Research and development services : If an arrangement is determined to contain a promise or obligation for the company to perform research and development services, the Company must determine whether these services are distinct from other promises in the arrangement. In assessing whether the services are distinct from the other promises, the Company considers the capabilities of the customer to perform these same services. In addition, the Company considers whether the customer can benefit from a promise for its intended purpose without the receipt of the remaining promise, whether the value of the promise is dependent on the unsatisfied promise, whether there are other vendors that could provide the remaining promise, and whether it is separately identifiable from the remaining promise. For research and development services that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Customer options: If an arrangement is determined to contain customer options that allow the customer to acquire additional goods or services, the goods and services underlying the customer options are not considered to be performance obligations at the outset of the arrangement, as they are contingent upon option exercise. The Company evaluates the customer options for material rights, that is, the option to acquire additional goods or services for free or at a discount. If the customer options are determined to represent a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. The Company allocates the transaction price to material rights using the practical alternative approach. The Company uses the practical alternative approach when the goods or services are both (i) similar to the original goods and services in the contract and (ii) provided in accordance with the terms of the original contract. Under this alternative, the Company allocates the total amount of consideration expected to be received from the customer to the total goods or services expected to be provided to the customer. Amounts allocated to a material right are not recognized as revenue until the option is exercised and the performance obligation is satisfied. Milestone payments: At the inception of each arrangement that includes milestone payments, the Company evaluates whether a significant reversal of cumulative revenue provided in conjunction with achieving the milestones is probable, and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant reversal of cumulative revenue would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. For other milestones, the Company evaluates factors such as the scientific, clinical, regulatory, commercial, and other risks that must be overcome to achieve the particular milestone in making this assessment. There is considerable judgment involved in determining whether it is probable that a significant reversal of cumulative revenue would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. Royalties: For arrangements that include sales-based royalties, including milestone payments based on a level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its licensing arrangements. Contract costs : The Company recognizes as an asset the incremental costs of obtaining a contract with a customer if the costs are expected to be recovered. As a practical expedient, the Company recognizes the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that we otherwise would have recognized is one year or less. To date, the Company has not incurred any incremental costs of obtaining a contract with a customer. For additional discussion of accounting for collaboration revenues, see Note 4, “Pfizer Collaboration and Equity Agreements.” Recently Issued Accounting Pronouncements The recently issued accounting pronouncements described in the Company’s audited financial statements as of and for the year ended December 31, 2017, and the notes thereto, which are included in the 2017 Annual Report on Form 10-K, have had no material changes during the three months ended March 31, 2018, except as described below. In February 2018, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (“ASU 2018-02”), which allows companies to make a one-time reclassification of the stranded tax effects (as defined by ASU 2018-02) from accumulated other comprehensive income to retained earnings as a result of the tax legislation enacted in December 2017, commonly known as the “Tax Cuts and Jobs Act” (the “Tax Act”), and requires certain disclosures about the stranded tax effects. The new guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company is currently evaluating the potential impact that the adoption of ASU 2018-02 may have on its consolidated financial statements. In March 2018, the FASB issued Accounting Standards Update No. 2018-05, Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 (“ASU 2018-05”). The standard amends Accounting Standards Codification 740, Income Taxes (“ASC 740”), to provide guidance on accounting for the tax effects of the Tax Act pursuant to Staff Accounting Bulletin No. 118. The Company is currently evaluating the new guidance included in ASU 2018-05, but does not expect it to have a material impact on its consolidated financial statements. Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, which amends the guidance for accounting for revenue from contracts with customers. This ASU supersedes the revenue recognition requirements in ASC Topic 605, Revenue Recognition, (“ASC 605”), and creates a new topic, ASC 606, Revenue from Contracts with Customers. In 2015 and 2016, the FASB issued additional ASUs related to ASC 606 that delayed the effective date of the guidance and clarified various aspects of the new revenue guidance, including principal versus agent considerations, identifying performance obligations, and licensing, and they include other improvements and practical expedients. The Company adopted this new standard on January 1, 2018 using the full retrospective transition method. Impact of Adoption As a result of adopting ASC 606 on January 1, 2018, the Company has revised its comparative financial statements for the prior year as if ASC 606 had been effective for that period. As a result, the following financial statement line items for fiscal year 2017 were affected. Condensed Consolidated Balance Sheets As of December 31, 2017 As revised under ASC 606 As originally reported under ASC 605 Effect of change (in thousands) Current portion of deferred revenue $ 1,275 $ 2,705 $ (1,430 ) Deferred revenue, net of current portion 7,241 5,607 1,634 Accumulated deficit (192,716 ) (192,512 ) (204 ) Condensed Consolidated Statements of Operations and Comprehensive Loss Three Months Ended March 31, 2017 As revised under ASC 606 As originally reported under ASC 605 Effect of change (in thousands, except per share data) Revenue $ 383 $ 676 $ (293 ) Loss from operations (20,207 ) (19,914 ) (293 ) Income tax provision (1,110 ) (1,303 ) 193 Net loss (21,096 ) (20,996 ) (100 ) Net loss per share attributable to ordinary shareholders— basic and diluted $ (0.90 ) $ (0.89 ) $ (0.01 ) Condensed Consolidated Statement of Cash Flows Three Months Ended March 31, 2017 As revised under ASC 606 As originally reported under ASC 605 Effect of change (in thousands) Net loss $ (21,096 ) $ (20,996 ) $ (100 ) Adjustments to reconcile net loss to net cash used in operating activities: Deferred income taxes (193 ) — (193 ) Changes in operating assets and liabilities: Deferred revenue (383 ) (676 ) 293 Net cash used in operating activities (17,418 ) (17,418 ) — Cash, cash equivalents and restricted cash, beginning of period 153,894 153,894 — Cash, cash equivalents and restricted cash, end of period 133,088 133,088 — The most significant changes relate to the Company’s revenue recognition pattern for the Pfizer Collaboration Agreement and the accounting for milestone payments. Under ASC 605, the Company was recognizing the revenue allocated to each unit of accounting on a straight‑line basis over the period the Company is expected to complete its obligations. Under ASC 606, the Company is recognizing the revenue allocated to each performance obligation measuring progress using an input method over the period the Company is expected to complete each performance obligation. Under ASC 605, the Company recognized revenue related to milestone payments as the milestone was achieved, using the milestone method. Under ASC 606, the Company performs an assessment of the probability of milestone achievement at each reporting date, and determines whether the cumulative revenue related to the milestone is at risk of significant reversal. For further discussion of the adoption of this standard, see Note 4, “Pfizer Collaboration and Equity Agreements.” In October 2016, the FASB issued Accounting Standards Update No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”). Under the new guidance, companies are required to recognize the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs, even though the pre-tax effects of that transaction are eliminated in consolidation. The amendments are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. These amendments should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings at the beginning of the period adopted. The Company adopted ASU 2016-16 effective January 1, 2018, which resulted in a $0.4 million cumulative-effect adjustment to retained earnings related to the intercompany sale of intellectual property on October 1, 2017. In November 2016, the FASB issued Accounting Standards Update No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (“ASU 2016-18”). ASU 2016-18 requires that an entity explain the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents on the statement of cash flows. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. This ASU is effective for annual and interim periods beginning after December 15, 2017, and is required to be adopted using a retrospective approach, with early adoption permitted. The Company adopted ASU 2016-18 effective January 1, 2018 on a retrospective basis which resulted in a change in presentation of restricted cash within the Company’s unaudited consolidated statements of cash flows.

Share-Based Compensation

Share-Based Compensation	3 Months Ended
	Mar. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation	3 . SHARE-BASED COMPENSATION The Wave Life Sciences Ltd. 2014 Equity Incentive Plan (the “2014 Plan”) authorizes the board of directors or a committee of the board of directors to grant incentive share options, non-qualified share options, share appreciation rights, restricted awards, which includes restricted shares and restricted share units (“RSUs”), and performance awards to eligible employees, consultants and directors of the Company. Options generally vest over periods of one to four years, and any options that are forfeited or cancelled are available to be granted again. The contractual life of options is generally five or ten years from the grant date. RSUs generally vest over a period of one or four years, and any RSUs that are forfeited are available to be granted again. During the three months ended March 31, 2018, 451,520 options and 309,247 RSUs were granted to employees of the Company. As of March 31, 2018, 975,301 ordinary shares remained available for future grant under the 2014 Plan.

Pfizer Collaboration and Equity

Pfizer Collaboration and Equity Agreements	3 Months Ended
	Mar. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Pfizer Collaboration and Equity Agreements	4. PFIZER COLLABORATION AND EQUITY AGREEMENTS In May 2016, the Company entered into a Research, License and Option Agreement, as amended (the “Pfizer Collaboration Agreement”), with Pfizer Inc. (“Pfizer”). Pursuant to the terms of the Pfizer Collaboration Agreement, the Company and Pfizer agreed to collaborate on the discovery, development and commercialization of stereopure oligonucleotide therapeutics for up to five programs (the “Pfizer Programs”), each directed at a genetically-defined hepatic target selected by Pfizer (the “Pfizer Collaboration”). The Company received $10.0 million as an upfront license fee under the Pfizer Collaboration Agreement. Subject to option exercises by Pfizer, the Company may earn potential research, development and commercial milestone payments, plus royalties, tiered up to low double-digits, on sales of any products that may result from the Pfizer Collaboration. None of the payments under the Pfizer Collaboration Agreement are refundable. Simultaneously with the entry into the Pfizer Collaboration Agreement, the Company entered into a Share Purchase Agreement (the “Pfizer Equity Agreement,” and together with the Pfizer Collaboration Agreement, the “Pfizer Agreements”) with C.P. Pharmaceuticals International C.V., an affiliate of Pfizer (the “Pfizer Affiliate”). Pursuant to the terms of the Pfizer Equity Agreement, the Pfizer Affiliate purchased 1,875,000 of the Company’s ordinary shares (the “Shares”) at a purchase price of $16.00 per share, for an aggregate purchase price of $30.0 million. The Company did not incur any material costs in connection with the issuance of the Shares. Under the Pfizer Collaboration Agreement, the parties agreed to collaborate during a four-year research term. During the research term, the Company is responsible to use its commercially reasonable efforts to advance up to five programs through to the selection of clinical candidates. At that stage, Pfizer may elect to license any of these Pfizer Programs exclusively and obtain exclusive rights to undertake the clinical development of the resulting clinical candidates into products and the potential commercialization of any such products thereafter. In addition, the Company received a non-exclusive, royalty-bearing sublicensable license to use Pfizer’s hepatic targeting technology in any of the Company’s own hepatic programs that are outside the scope of the Pfizer Collaboration (the “Wave Programs”). If the Company uses this technology on the Wave Programs, Pfizer is eligible to receive potential development and commercial milestone payments from the Company. Pfizer is also eligible to receive tiered royalties on sales of any products that include Pfizer’s hepatic targeting technology. Pfizer nominated two hepatic targets upon entry into the Pfizer Collaboration in May 2016. The Pfizer Collaboration Agreement provides Pfizer with options to nominate up to three additional programs by making nomination milestone payments. Pfizer nominated the third, fourth and fifth hepatic targets in August 2016, March 2018 and April 2018, respectively. The Pfizer Collaboration is managed by a joint steering committee in which both parties are represented equally, which will oversee the scientific progression of each Pfizer Program up to the clinical candidate stage. During the four-year research term and for a period of two years thereafter, the Company has agreed to work exclusively with Pfizer with respect to using any of the Company’s stereopure oligonucleotide technology that is specific for the applicable hepatic target which is the basis of any Pfizer Program. Within 120 days of receiving a data package for a candidate under each nominated program, Pfizer may exercise an option to obtain a license to develop, manufacture and commercialize the program candidate by paying an exercise price per program. The Company assessed this arrangement in accordance with ASC 606 and concluded that the contract counterparty, Pfizer, is a customer. The Company identified the following promises under the arrangement: (1) the non-exclusive, royalty-free research and development license; (2) the research and development services for Programs 1 and 2; (3) the program nomination options for Programs 3, 4 and 5; (4) the research and development services associated with Programs 3, 4 and 5; (5) the options to obtain a license to develop, manufacture and commercialize Programs 1 and 2; and (6) the options to obtain a license to develop, manufacture and commercialize Programs 3, 4 and 5. The research and development services for each of Programs 1 and 2 were determined to not be distinct from the research and development license and should be combined into a single performance obligation for each program. The promises under the Pfizer Collaboration Agreement relate primarily to the research and development required by the Company for each of the programs nominated by Pfizer. Additionally, the Company determined that the program nomination options for Programs 3, 4 and 5 were priced at a discount, and as such provide material rights to Pfizer, representing three separate performance obligations. The research and development services associated with Programs 3, 4 and 5 and the options to obtain a license to develop, manufacture and commercialize Programs 3, 4 and 5 are subject to Pfizer’s exercise of the program nomination options for such programs and therefore do not represent performance obligations at the outset of the arrangement. The options to obtain a license to develop, manufacture and commercialize Programs 1 and 2 do not represent material rights; as such, they are not representative of performance obligations at the outset of the arrangement. Based on these assessments, the Company identified five performance obligations in the Pfizer Collaboration Agreement: (1) research and development services and license for Program 1; (2) research and development services and license for Program 2; (3) material right provided for the option to nominate Program 3; (4) material right provided for the option to nominate Program 4; and (5) material right provided for the option to nominate Program 5. At the outset of the arrangement, the transaction price included only the $10.0 million up-front consideration received. The Company analyzed this up-front consideration and determined that the Pfizer Collaboration Agreement did not contain a significant financing component. The program nomination option exercise fees for research and development services associated with Programs 3, 4 and 5 that may be received are excluded from the transaction price until each customer option is exercised. The potential milestone payments were excluded from the transaction price, as all milestone amounts were fully constrained at the inception of the Pfizer Collaboration Agreement. The exercise fees for the options to obtain a license to develop, manufacture and commercialize Programs 3, 4 and 5 that may be received are excluded from the transaction price until each customer option is exercised. The Company will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and, if necessary, will adjust its estimate of the transaction price. During the three months ended September 30, 2017, it became probable that a significant reversal of cumulative revenue would not occur for a developmental milestone under the Pfizer Collaboration Agreement. At such time, the associated consideration was added to the estimated transaction price and allocated to the existing performance obligations, and the Company recognized a cumulative catch-up to revenue for this developmental milestone, representing the amount that would have been recognized had the milestone payment been included in the transaction price from the outset of the arrangement. The remainder will be recognized in the same manner as the remaining, unrecognized transaction price over the remaining period until each performance obligation is satisfied. The milestone was achieved in November 2017. Revenue associated with the performance obligations relating to Programs 1 and 2 is being recognized as revenue as the research and development services are provided using an input method, according to the full-time employee (“FTE”) hours incurred on each program and the FTE hours expected to be incurred in the future to satisfy the performance obligation. The transfer of control occurs over time and, in management’s judgment, is the best measure of progress towards satisfying the performance obligation. The amount allocated to the three material rights will be recognized as the underlying research and development services are provided commencing from the date that Pfizer exercises each respective option, or immediately as each option expires unexercised. The amounts received that have not yet been recognized as revenue are recorded in deferred revenue on the Company’s consolidated balance sheet. In August 2016, Pfizer exercised its option to nominate Program 3. The Company allocated the transaction price amount allocated to the material right at inception of the arrangement plus the program nomination option exercise fee paid by Pfizer at the time of exercising the option) to a new performance obligation, which will be recognized as revenue as the research and development services are provided using the same method as the performance obligations relating to Programs 1 and 2. The stated term of the Pfizer Collaboration Agreement commenced on May 5, 2016 and terminates on the date of the last to expire payment obligation with respect to each Pfizer Program and with respect to each Wave Program, expires on a program-by-program basis accordingly. Pfizer may terminate its rights related to a Pfizer Program under the Pfizer Collaboration Agreement at its own convenience upon 90 days’ notice to the Company. The Company may also terminate its rights related to a Wave Program at its own convenience upon 90 days’ notice to Pfizer. The Pfizer Collaboration Agreement may also be terminated by either party in the event of an uncured material breach of the Pfizer Collaboration Agreement by the other party. Through March 31, 2018, the Company had recognized revenue of $6.4 million as collaboration revenue in the Company’s consolidated statements of operations and comprehensive loss under the Pfizer Collaboration Agreement. The $1.4 million of revenue recognized during the quarter ended March 31, 2018 was included in deferred revenue as of December 31, 2017. The aggregate amount of the transaction price allocated to the Company’s unsatisfied and partially unsatisfied performance obligations and recorded in deferred revenue at March 31, 2018 is $7.1 million, of which $1.3 million is included in current liabilities. The Company expects to recognize this amount according to FTE hours incurred, over the remaining research term, which is 25 months as of March 2018.

Net Loss Per Ordinary Share

Net Loss Per Ordinary Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Net Loss Per Ordinary Share	5. NET LOSS PER ORDINARY SHARE The Company applies the two-class method to calculate its basic and diluted net loss per share attributable to ordinary shareholders, as its Series A preferred shares are participating securities. The two-class method is an earnings allocation formula that treats a participating security as having rights to earnings that otherwise would have been available to ordinary shareholders. However, for the periods presented, the two-class method does not impact the net loss per ordinary share as the Company was in a net loss position for each of the periods presented and holders of Series A preferred shares d o not participate in losses. Basic loss per share is computed by dividing net loss attributable to ordinary shareholders by the weighted-average number of ordinary shares used in computing net loss per share attributable to ordinary shareholders. The Company’s potentially dilutive shares, which include outstanding share options to purchase ordinary shares, RSUs and Series A preferred shares, are considered to be ordinary share equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. The following ordinary share equivalents, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share attributable to ordinary shareholders for the periods indicated because including them would have had an anti-dilutive effect: As of March 31, 2018 2017 Options to purchase ordinary shares 4,077,623 3,776,572 RSUs 420,517 191,657 Series A preferred shares 3,901,348 3,901,348

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	6. INCOME TAXES The Company is a Singapore multi-national company subject to taxation in the United States and various other jurisdictions. During the three months ended March 31, 2018 and 2017, the Company recorded an income tax provision of $0.2 million and $1.1 million, respectively. The income tax provision recorded during the three months ended March 31, 2018 was due to provision to return adjustments related to the filing of Wave Japan’s 2017 tax return. The income tax provision recorded during the three months ended March 31, 2017 was primarily the result of U.S. income generated under research and management services arrangements between one of the Company’s subsidiaries, Wave USA, and the Company’s Singapore parent company. During the three months ended March 31, 2018, the Company recorded no income tax benefits for the net operating losses incurred in Singapore, the United States, Japan, the United Kingdom or Ireland, due to its uncertainty of realizing a benefit from those items. During the three months ended March 31, 2017, the Company recorded no income tax benefits for the net operating losses incurred in Singapore, Japan or Ireland, due to its uncertainty of realizing a benefit from those items. The Company’s reserves related to taxes and its accounting for uncertain tax positions are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is more-likely-than-not to be realized following resolution of any potential contingencies present related to the tax benefit.

Related Parties

Related Parties	3 Months Ended
	Mar. 31, 2018
Related Party Transactions [Abstract]
Related Parties	7. RELATED PARTIES The Company had the following related party transactions for the periods presented in the accompanying consolidated financial statements, which have not otherwise been discussed in these notes to the consolidated financial statements: • The Company held cash of $0.1 million in depository accounts with Kagoshima Bank, Ltd., an affiliate of one of the Company’s shareholders, Kagoshima Shinsangyo Sousei Investment Limited Partnership, • Pursuant to the terms of various service agreements with Shin Nippon Biomedical Laboratories Ltd., one of the Company’s shareholders, • In 2012, the Company entered into a consulting agreement for scientific advisory services with Dr. Gregory L. Verdine, one of the Company’s founders and a member of the Company’s board of directors. The consulting agreement does not have a specific term and may be terminated by either party upon 14 days’ prior written notice. Pursuant to the consulting agreement, the Company pays Dr. Verdine approximately $13 thousand per month, plus reimbursement of certain expenses.

Subsequent Event

Subsequent Event	3 Months Ended
	Mar. 31, 2018
Subsequent Events [Abstract]
Subsequent Event	8. SUBSEQUENT EVENTS Takeda Collaboration and Equity Investment In February 2018, Wave USA and Wave UK entered into a global strategic collaboration with Takeda (the “Takeda Collaboration”), pursuant to which Wave USA, Wave UK and Takeda agreed to collaborate on the research, development and commercialization of oligonucleotide therapeutics for disorders of the CNS. The Takeda Collaboration provides Wave with at least $230.0 million in committed cash and Takeda with the option to co-develop and co-commercialize our CNS development programs in HD, ALS and FTD, as well as our discovery-stage program targeting ATXN3 for the treatment of SCA3. In addition, Takeda will have the right to exclusively license multiple preclinical programs for CNS disorders, including Alzheimer’s disease and Parkinson’s disease. In April 2018, the Takeda Collaboration became effective and Takeda paid us $110.0 million as an upfront payment. Takeda also agreed to fund our research and preclinical activities in the amount of $60.0 million during the four-year research term and to reimburse us for any collaboration-budgeted research and preclinical expenses incurred by us that exceed that amount. Simultaneously with our entry into the collaboration and license agreement with Takeda (the “Takeda Collaboration Agreement”), we entered into a share purchase agreement with Takeda pursuant to which we agreed to sell to Takeda 1,096,892 of our ordinary shares at a purchase price of $54.70 per share (the “Takeda Equity Investment”). In April 2018, we closed the Takeda Equity Investment and received aggregate cash proceeds of $60.0 million.

Significant Accounting Polici14

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Unaudited Interim Financial Data	Unaudited Interim Financial Data The accompanying interim consolidated balance sheet as of March 31, 2018, the related interim consolidated statements of operations and comprehensive loss for the three months ended March 31, 2018 and 2017 and cash flows for the three months ended March 31, 2018 and 2017, and the related interim information contained within the notes to the consolidated financial statements have been prepared in accordance with the rules and regulations of the SEC for interim financial information. Accordingly, they do not include all of the information and the notes required by U.S. GAAP for complete financial statements. The financial data and other information disclosed in these notes related to the three months ended March 31, 2018 and 2017 are unaudited. In the opinion of management, the unaudited interim consolidated financial statements reflect all adjustments, consisting of normal and recurring adjustments, necessary for the fair presentation of the Company’s financial position and results of operations for the three months ended March 31, 2018 and 2017. The results of operations for the interim periods are not necessarily indicative of the results to be expected for the year ending December 31, 2018 or any other interim period or future year or period.
Principles of Consolidation	Principles of Consolidation The Company’s consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.
Revenue Recognition	Revenue Recognition Effective January 1, 2018, the Company adopted Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“ASC 606”), using the full retrospective transition method. Under this method, the Company revised its consolidated financial statements for the years ended December 31, 2017 and 2016, and applicable interim periods within those years, as if ASC 606 had been effective for those periods. This standard applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, and financial instruments. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, the entity performs the following five-step analysis: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step analysis to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract, determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. The Company has entered into collaboration agreements for research, development, and commercial services, under which the Company licenses certain rights to its product candidates to third parties. The terms of these arrangements typically include payment to the Company of one or more of the following: non-refundable, upfront license fees; reimbursement of certain costs; customer option exercise fees; development, regulatory and commercial milestone payments; and royalties on net sales of licensed products. Any variable consideration is constrained, and therefore, the cumulative revenue associated with this consideration is not recognized until it is deemed not to be at significant risk of reversal. In determining the appropriate amount of revenue to be recognized as the Company fulfills its obligations under each of its agreements for which the collaboration partner is also a customer, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. As part of the accounting for these arrangements, the Company must use significant judgment to determine: (a) the number of performance obligations based on the determination under step (ii) above; (b) the transaction price under step (iii) above; and (c) the timing of satisfaction of performance obligations as a measure of progress in step (v) above. The Company uses significant judgment to determine whether milestones or other variable consideration, except for royalties, should be included in the transaction price as described further below. Amounts received prior to revenue recognition are recorded as deferred revenue. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current portion of deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. Licenses of intellectual property: In assessing whether a promise or performance obligation is distinct from the other promises, the Company considers factors such as the research, development, manufacturing and commercialization capabilities of the customer and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the customer can benefit from a promise for its intended purpose without the receipt of the remaining promise, whether the value of the promise is dependent on the unsatisfied promise, whether there are other vendors that could provide the remaining promise, and whether it is separately identifiable from the remaining promise. For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Research and development services : If an arrangement is determined to contain a promise or obligation for the company to perform research and development services, the Company must determine whether these services are distinct from other promises in the arrangement. In assessing whether the services are distinct from the other promises, the Company considers the capabilities of the customer to perform these same services. In addition, the Company considers whether the customer can benefit from a promise for its intended purpose without the receipt of the remaining promise, whether the value of the promise is dependent on the unsatisfied promise, whether there are other vendors that could provide the remaining promise, and whether it is separately identifiable from the remaining promise. For research and development services that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Customer options: If an arrangement is determined to contain customer options that allow the customer to acquire additional goods or services, the goods and services underlying the customer options are not considered to be performance obligations at the outset of the arrangement, as they are contingent upon option exercise. The Company evaluates the customer options for material rights, that is, the option to acquire additional goods or services for free or at a discount. If the customer options are determined to represent a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. The Company allocates the transaction price to material rights using the practical alternative approach. The Company uses the practical alternative approach when the goods or services are both (i) similar to the original goods and services in the contract and (ii) provided in accordance with the terms of the original contract. Under this alternative, the Company allocates the total amount of consideration expected to be received from the customer to the total goods or services expected to be provided to the customer. Amounts allocated to a material right are not recognized as revenue until the option is exercised and the performance obligation is satisfied. Milestone payments: At the inception of each arrangement that includes milestone payments, the Company evaluates whether a significant reversal of cumulative revenue provided in conjunction with achieving the milestones is probable, and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant reversal of cumulative revenue would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. For other milestones, the Company evaluates factors such as the scientific, clinical, regulatory, commercial, and other risks that must be overcome to achieve the particular milestone in making this assessment. There is considerable judgment involved in determining whether it is probable that a significant reversal of cumulative revenue would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. Royalties: For arrangements that include sales-based royalties, including milestone payments based on a level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its licensing arrangements. Contract costs : The Company recognizes as an asset the incremental costs of obtaining a contract with a customer if the costs are expected to be recovered. As a practical expedient, the Company recognizes the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that we otherwise would have recognized is one year or less. To date, the Company has not incurred any incremental costs of obtaining a contract with a customer. For additional discussion of accounting for collaboration revenues, see Note 4, “Pfizer Collaboration and Equity Agreements.”
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements The recently issued accounting pronouncements described in the Company’s audited financial statements as of and for the year ended December 31, 2017, and the notes thereto, which are included in the 2017 Annual Report on Form 10-K, have had no material changes during the three months ended March 31, 2018, except as described below. In February 2018, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (“ASU 2018-02”), which allows companies to make a one-time reclassification of the stranded tax effects (as defined by ASU 2018-02) from accumulated other comprehensive income to retained earnings as a result of the tax legislation enacted in December 2017, commonly known as the “Tax Cuts and Jobs Act” (the “Tax Act”), and requires certain disclosures about the stranded tax effects. The new guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company is currently evaluating the potential impact that the adoption of ASU 2018-02 may have on its consolidated financial statements. In March 2018, the FASB issued Accounting Standards Update No. 2018-05, Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 (“ASU 2018-05”). The standard amends Accounting Standards Codification 740, Income Taxes (“ASC 740”), to provide guidance on accounting for the tax effects of the Tax Act pursuant to Staff Accounting Bulletin No. 118. The Company is currently evaluating the new guidance included in ASU 2018-05, but does not expect it to have a material impact on its consolidated financial statements. Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, which amends the guidance for accounting for revenue from contracts with customers. This ASU supersedes the revenue recognition requirements in ASC Topic 605, Revenue Recognition, (“ASC 605”), and creates a new topic, ASC 606, Revenue from Contracts with Customers. In 2015 and 2016, the FASB issued additional ASUs related to ASC 606 that delayed the effective date of the guidance and clarified various aspects of the new revenue guidance, including principal versus agent considerations, identifying performance obligations, and licensing, and they include other improvements and practical expedients. The Company adopted this new standard on January 1, 2018 using the full retrospective transition method. Impact of Adoption As a result of adopting ASC 606 on January 1, 2018, the Company has revised its comparative financial statements for the prior year as if ASC 606 had been effective for that period. As a result, the following financial statement line items for fiscal year 2017 were affected. Condensed Consolidated Balance Sheets As of December 31, 2017 As revised under ASC 606 As originally reported under ASC 605 Effect of change (in thousands) Current portion of deferred revenue $ 1,275 $ 2,705 $ (1,430 ) Deferred revenue, net of current portion 7,241 5,607 1,634 Accumulated deficit (192,716 ) (192,512 ) (204 ) Condensed Consolidated Statements of Operations and Comprehensive Loss Three Months Ended March 31, 2017 As revised under ASC 606 As originally reported under ASC 605 Effect of change (in thousands, except per share data) Revenue $ 383 $ 676 $ (293 ) Loss from operations (20,207 ) (19,914 ) (293 ) Income tax provision (1,110 ) (1,303 ) 193 Net loss (21,096 ) (20,996 ) (100 ) Net loss per share attributable to ordinary shareholders— basic and diluted $ (0.90 ) $ (0.89 ) $ (0.01 ) Condensed Consolidated Statement of Cash Flows Three Months Ended March 31, 2017 As revised under ASC 606 As originally reported under ASC 605 Effect of change (in thousands) Net loss $ (21,096 ) $ (20,996 ) $ (100 ) Adjustments to reconcile net loss to net cash used in operating activities: Deferred income taxes (193 ) — (193 ) Changes in operating assets and liabilities: Deferred revenue (383 ) (676 ) 293 Net cash used in operating activities (17,418 ) (17,418 ) — Cash, cash equivalents and restricted cash, beginning of period 153,894 153,894 — Cash, cash equivalents and restricted cash, end of period 133,088 133,088 — The most significant changes relate to the Company’s revenue recognition pattern for the Pfizer Collaboration Agreement and the accounting for milestone payments. Under ASC 605, the Company was recognizing the revenue allocated to each unit of accounting on a straight‑line basis over the period the Company is expected to complete its obligations. Under ASC 606, the Company is recognizing the revenue allocated to each performance obligation measuring progress using an input method over the period the Company is expected to complete each performance obligation. Under ASC 605, the Company recognized revenue related to milestone payments as the milestone was achieved, using the milestone method. Under ASC 606, the Company performs an assessment of the probability of milestone achievement at each reporting date, and determines whether the cumulative revenue related to the milestone is at risk of significant reversal. For further discussion of the adoption of this standard, see Note 4, “Pfizer Collaboration and Equity Agreements.” In October 2016, the FASB issued Accounting Standards Update No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”). Under the new guidance, companies are required to recognize the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs, even though the pre-tax effects of that transaction are eliminated in consolidation. The amendments are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. These amendments should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings at the beginning of the period adopted. The Company adopted ASU 2016-16 effective January 1, 2018, which resulted in a $0.4 million cumulative-effect adjustment to retained earnings related to the intercompany sale of intellectual property on October 1, 2017. In November 2016, the FASB issued Accounting Standards Update No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (“ASU 2016-18”). ASU 2016-18 requires that an entity explain the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents on the statement of cash flows. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. This ASU is effective for annual and interim periods beginning after December 15, 2017, and is required to be adopted using a retrospective approach, with early adoption permitted. The Company adopted ASU 2016-18 effective January 1, 2018 on a retrospective basis which resulted in a change in presentation of restricted cash within the Company’s unaudited consolidated statements of cash flows.

Significant Accounting Polici15

Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2018
ASC 606 [Member]
Summary of Result of Adopting ASC 606 on Financial Statement	Impact of Adoption As a result of adopting ASC 606 on January 1, 2018, the Company has revised its comparative financial statements for the prior year as if ASC 606 had been effective for that period. As a result, the following financial statement line items for fiscal year 2017 were affected. Condensed Consolidated Balance Sheets As of December 31, 2017 As revised under ASC 606 As originally reported under ASC 605 Effect of change (in thousands) Current portion of deferred revenue $ 1,275 $ 2,705 $ (1,430 ) Deferred revenue, net of current portion 7,241 5,607 1,634 Accumulated deficit (192,716 ) (192,512 ) (204 ) Condensed Consolidated Statements of Operations and Comprehensive Loss Three Months Ended March 31, 2017 As revised under ASC 606 As originally reported under ASC 605 Effect of change (in thousands, except per share data) Revenue $ 383 $ 676 $ (293 ) Loss from operations (20,207 ) (19,914 ) (293 ) Income tax provision (1,110 ) (1,303 ) 193 Net loss (21,096 ) (20,996 ) (100 ) Net loss per share attributable to ordinary shareholders— basic and diluted $ (0.90 ) $ (0.89 ) $ (0.01 ) Condensed Consolidated Statement of Cash Flows Three Months Ended March 31, 2017 As revised under ASC 606 As originally reported under ASC 605 Effect of change (in thousands) Net loss $ (21,096 ) $ (20,996 ) $ (100 ) Adjustments to reconcile net loss to net cash used in operating activities: Deferred income taxes (193 ) — (193 ) Changes in operating assets and liabilities: Deferred revenue (383 ) (676 ) 293 Net cash used in operating activities (17,418 ) (17,418 ) — Cash, cash equivalents and restricted cash, beginning of period 153,894 153,894 — Cash, cash equivalents and restricted cash, end of period 133,088 133,088 —

Net Loss Per Ordinary Share (Ta

Net Loss Per Ordinary Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Anti-Dilutive Shares Excluded from Calculation of Diluted Net Loss Per Ordinary Share	The following ordinary share equivalents, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share attributable to ordinary shareholders for the periods indicated because including them would have had an anti-dilutive effect: As of March 31, 2018 2017 Options to purchase ordinary shares 4,077,623 3,776,572 RSUs 420,517 191,657 Series A preferred shares 3,901,348 3,901,348

The Company - Additional Inform

The Company - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	May 31, 2016	Mar. 31, 2018
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Aggregate net proceeds from private placement, public offering and collaborations		$ 323.2
Net proceeds from private placements		89.3
Research, License and Option Agreement [Member] | Pfizer Inc. [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront amount related to research and development services	$ 10	40
Issuance of ordinary shares, net of offering costs	$ 30	30
Underwriters Over-Allotment Option [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Proceeds from initial public offering, net of offering costs and underwriter commissions		100.4
Follow-On Underwritten Public Offering [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Proceeds from issuance of ordinary shares, net of offering costs		$ 93.5

Significant Accounting Polici18

Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Jan. 01, 2018
Significant Accounting Policies [Line Items]
Revenue recognition perfomance obligation, expected time satisfaction period	12 months
Accounting Standards Update No. 2016-16 [Member]
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment to retained earnings		$ 0.4

Significant Accounting Polici19

Significant Accounting Policies - Summary of Result of Adopting ASC 606 on Financial Statement - Condensed Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Condensed Balance Sheet Statements Captions [Line Items]
Current portion of deferred revenue	$ 1,275	$ 1,275
Deferred revenue, net of current portion	5,819	7,241
Accumulated deficit	$ (228,309)	(192,716)
As Originally Reported Under ASC 605 [Member] | ASC 606 [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Current portion of deferred revenue		2,705
Deferred revenue, net of current portion		5,607
Accumulated deficit		(192,512)
Effect of Change [Member] | ASC 606 [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Current portion of deferred revenue		(1,430)
Deferred revenue, net of current portion		1,634
Accumulated deficit		$ (204)

Significant Accounting Polici20

Significant Accounting Policies - Summary of Result of Adopting ASC 606 on Financial Statement - Condensed Consolidated Statements of Operations and Comprehensive Loss (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Condensed Income Statements Captions [Line Items]
Revenue		$ 383
Loss from operations	$ (35,775)	(20,207)
Income tax provision	(172)	(1,110)
Net loss	$ (35,241)	$ (21,096)
Net loss per share attributable to ordinary shareholders—basic and diluted	$ (1.26)	$ (0.90)
As Originally Reported Under ASC 605 [Member] | ASC 606 [Member]
Condensed Income Statements Captions [Line Items]
Revenue		$ 676
Loss from operations		(19,914)
Income tax provision		(1,303)
Net loss		$ (20,996)
Net loss per share attributable to ordinary shareholders—basic and diluted		$ (0.89)
Effect of Change [Member] | ASC 606 [Member]
Condensed Income Statements Captions [Line Items]
Revenue		$ (293)
Loss from operations		(293)
Income tax provision		193
Net loss		$ (100)
Net loss per share attributable to ordinary shareholders—basic and diluted		$ (0.01)

Significant Accounting Polici21

Significant Accounting Policies Summary of Result of Adopting ASC 606 on Financial Statement - Condensed Consolidated Statement of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Condensed Cash Flow Statements Captions [Line Items]
Net loss	$ (35,241)	$ (21,096)
Adjustments to reconcile net loss to net cash used in operating activities:
Deferred income taxes		(193)
Changes in operating assets and liabilities:
Deferred revenue	(1,422)	(383)
Net cash used in operating activities	(32,426)	(17,418)
Cash, cash equivalents and restricted cash, beginning of period	146,113	153,894
Cash, cash equivalents and restricted cash, end of period	$ 114,103	133,088
As Originally Reported Under ASC 605 [Member] | ASC 606 [Member]
Condensed Cash Flow Statements Captions [Line Items]
Net loss		(20,996)
Changes in operating assets and liabilities:
Deferred revenue		(676)
Net cash used in operating activities		(17,418)
Cash, cash equivalents and restricted cash, beginning of period		153,894
Cash, cash equivalents and restricted cash, end of period		133,088
Effect of Change [Member] | ASC 606 [Member]
Condensed Cash Flow Statements Captions [Line Items]
Net loss		(100)
Adjustments to reconcile net loss to net cash used in operating activities:
Deferred income taxes		(193)
Changes in operating assets and liabilities:
Deferred revenue		$ 293

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018shares
RSUs [Member]
Share-based Compensation Arrangement By Share-based Payment Award [Line Items]
Shares granted to employees	309,247
Options [Member]
Share-based Compensation Arrangement By Share-based Payment Award [Line Items]
Options granted to employees	451,520
2014 Plan [Member]
Share-based Compensation Arrangement By Share-based Payment Award [Line Items]
Ordinary shares available for future grant	975,301
2014 Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement By Share-based Payment Award [Line Items]
Vesting period	1 year
Contractual life of options	5 years
2014 Plan [Member] | Minimum [Member] | RSUs [Member]
Share-based Compensation Arrangement By Share-based Payment Award [Line Items]
Vesting period	1 year
2014 Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement By Share-based Payment Award [Line Items]
Vesting period	4 years
Contractual life of options	10 years
2014 Plan [Member] | Maximum [Member] | RSUs [Member]
Share-based Compensation Arrangement By Share-based Payment Award [Line Items]
Vesting period	4 years

Pfizer Collaboration and Equi23

Pfizer Collaboration and Equity Agreements - Additional Information (Detail)	May 05, 2016	May 31, 2016USD ($)Program$ / sharesshares	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue			$ 1,422,000	$ 383,000
Current portion of deferred revenue			$ 1,275,000		$ 1,275,000
Pfizer Inc. [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of research programs, counterparty nomination | Program		5
Research term, description			Under the Pfizer Collaboration Agreement, the parties agreed to collaborate during a four-year research term. During the research term, the Company is responsible to use its commercially reasonable efforts to advance up to five programs through to the selection of clinical candidates. At that stage, Pfizer may elect to license any of these Pfizer Programs exclusively and obtain exclusive rights to undertake the clinical development of the resulting clinical candidates into products and the potential commercialization of any such products thereafter.
Collaboration agreement, additional period after research program		2 years
Collaboration agreement, data package receiving period		120 days
Up-front consideration received		$ 10,000,000
Revenue recognized			$ 6,400,000
Deferred revenue			7,100,000
Current portion of deferred revenue			$ 1,300,000
Remaining research term			25 months
Research, License and Option Agreement [Member] | Pfizer Inc. [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront amount related to research and development services		10,000,000	$ 40,000,000
Collaboration agreement refundable		$ 0
Shares issued under equity agreement | shares		1,875,000
Equity investment aggregate purchase price		$ 30,000,000	$ 30,000,000
Purchase price per share | $ / shares		$ 16
Collaborative agreement research term		4 years
Collaboration agreement termination period	90 days

Net Loss Per Ordinary Share - A

Net Loss Per Ordinary Share - Anti-Dilutive Shares Excluded from Calculation of Diluted Net Loss Per Ordinary Share (Detail) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from calculation of diluted net loss per share	4,077,623	3,776,572
RSUs [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from calculation of diluted net loss per share	420,517	191,657
Series A Preferred Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from calculation of diluted net loss per share	3,901,348	3,901,348

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Taxes [Line Items]
Income tax benefit (provision)	$ (172,000)	$ (1,110,000)
United States [Member]
Income Taxes [Line Items]
Income tax benefit (provision)	0
United States [Member] | Adjustments Related to Filing of Wave Japan’s 2017 Tax Return [Member]
Income Taxes [Line Items]
Income tax benefit (provision)	(200,000)
United States [Member] | Research and Management Services Arrangements [Member]
Income Taxes [Line Items]
Income tax benefit (provision)		(1,100,000)
Japan [Member]
Income Taxes [Line Items]
Income tax benefit (provision)	0	0
Singapore [Member]
Income Taxes [Line Items]
Income tax benefit (provision)	0	0
Ireland [Member]
Income Taxes [Line Items]
Income tax benefit (provision)	0	0
United Kingdom [Member]
Income Taxes [Line Items]
Income tax benefit (provision)	$ 0	$ 0

Related Parties - Additional In

Related Parties - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Third-Party Investor [Member]
Related Party Transaction [Line Items]
Related party transaction amount			$ 100
Shin Nippon Biomedical Laboratories Ltd. (SNBL) [Member]
Related Party Transaction [Line Items]
Payment for contract research services	$ 800
Shin Nippon Biomedical Laboratories Ltd. (SNBL) [Member] | Maximum [Member]
Related Party Transaction [Line Items]
Payment for contract research services		$ 100
Scientific Advisor [Member] | Consulting Agreement [Member]
Related Party Transaction [Line Items]
Consulting agreement termination notice period	14 days
Consulting service expenses	$ 13

Subsequent Event - Additional I

Subsequent Event - Additional Information (Detail) - Takeda [Member] - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Apr. 30, 2018	Feb. 28, 2018
Collaboration And License Agreement [Member] | Minimum [Member]
Subsequent Event [Line Items]
Collaboration agreement, committed cash		$ 230
Collaboration And License Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Upfront payment under collaboration agreement	$ 110
Collaboration and license agreement month and year	2018-02
Fund receivable for research and preclinical activities	$ 60
Research term under collaboration and license agreement	4 years
Collaboration and Share Purchase Agreements [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Shares issued and sale under equity agreement	1,096,892
Purchase price per share	$ 54.70
Proceeds from issuance of ordinary shares, net of offering costs	$ 60
Equity investment agreement official closure month and year	2018-04