Zymeworks Inc.

QUARTERLY REPORT ON FORM 10-Q

For the Quarter Ended September 30, 2026

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q includes “forward-looking statements” or information within the meaning of applicable securities legislation, including Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). Forward-looking statements include statements that may relate to our plans, objectives, goals, strategies, future events, future revenue or performance, capital expenditures, financing needs and other information that is not historical information. Many of these statements appear, in particular, under the headings “Business,” “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations.” Forward-looking statements can often be identified by the use of terminology such as “subject to,” “believe,” “anticipate,” “plan,” “expect,” “intend,” “estimate,” “project,” “may,” “will,” “should,” “would,” “could,” “can,” the negatives thereof, variations thereon and similar expressions, or by discussions of strategy. In addition, any statements or information that refer to expectations, beliefs, plans, projections, objectives, performance or other characterizations of future events or circumstances, including any underlying assumptions, are forward-looking. In particular, these forward-looking statements include, but are not limited to, statements about:

•the size of our addressable markets and our or our strategic partners’ ability to commercialize product candidates;

•the achievement of advances in and expansion of our therapeutic platforms and antibody engineering expertise;

•the likelihood of our or our strategic partners’ product candidate development and clinical trial progression, initiation or success;

•the receipt of milestone and royalty revenue from existing or potential new partnerships;

•the evolution of our business strategy related to anticipated and potential future milestones and royalty streams and existing and potential new partnerships;

•our ability to compound long-term stockholder value; and

•our and our strategic partners’ ability to predict and manage government regulation.

All forward-looking statements, including, without limitation, those related to our examination of historical operating trends, are based upon our current expectations and various assumptions. Certain assumptions made in preparing the forward-looking statements include:

•our ability to manage the evolution of our business strategy effectively;

•the absence of material adverse changes in our industry or the global economy;

•our ability to understand and predict trends in our industry and markets;

•our ability to enter into and maintain good business relationships with our strategic partners;

•our ability to comply with and navigate current and future regulatory standards, policies and programs, some of which are rapidly changing;

•our ability to protect our intellectual property rights;

•our continued compliance with third-party license terms and the non-infringement of third-party intellectual property rights;

•our ability to realize the anticipated benefits from our acquisition of Theravance Biopharma, Inc. ("Theravance"), including future performance of the YUPELRI and TRELEGY ELLIPTA products;

•our ability to manage and integrate any acquisitions we may pursue, including our acquisition of Theravance;

•our ability to identify, successfully compete for and acquire attractive royalty-generating assets;

•the availability of suitable acquisition or in-licensing opportunities or strategic partners that are consistent with the evolution of our business strategy;

•our continued ability to receive milestones and royalties from current and future collaborations;

•our ability to retain key personnel; and

•our ability to raise sufficient debt, equity, or non-dilutive financing to support our strategy and business objectives.

We believe there is a reasonable basis for our expectations and beliefs, but they are inherently uncertain. We may not realize our expectations, and our beliefs may not prove correct. Actual results could differ materially from those described or implied by such

i forward-looking statements. The following uncertainties and factors, among others (including those referred to in the section titled “Risk Factors”), could affect future performance and cause actual results to differ materially from those matters expressed in or implied by forward-looking statements:

•the potential success of our royalty-driven asset aggregation strategy;

•the potential disruption of our business and dilution of our shareholdings associated with acquisitions, joint ventures and other business development transactions;

•our ability to acquire favorable assets and progress them through preclinical and clinical development;

•our and our strategic partners’ discretion to discontinue or reprioritize the development of any of our product candidates;

•our ability to achieve milestones and receive associated milestone payments and royalties pursuant to the terms of our collaboration agreements, including the Amended Jazz Collaboration Agreement (as defined below);

•our ability to maintain existing and future strategic partnerships;

•our ability to realize the anticipated benefits of our strategic partnerships;

•our ability to secure future strategic partners;

•our ability to satisfy obligations and realize expected benefits under our financing arrangements, which may depend on future royalties and other factors that are subject to uncertainty;

•our ability to face significant competition, including generic and biosimilar products, as well as competition for potential acquisitions and other business development transactions we may pursue;

•our or our strategic partners’ ability to obtain regulatory approval for product candidates without significant delays;

•the predictive value of our or our strategic partners’ current or planned clinical trials;

•delays with respect to the development and commercialization of our or our strategic partners’ product candidates, which may cause increased costs or delay receipt of product revenue;

•our or any of our strategic partners’ ability to enroll subjects in clinical trials and thereby complete trials on a timely basis;

•the design or our execution of clinical trials may not support regulatory approval, including where clinical trials are conducted outside the United States;

•risks and uncertainties related to our acquisition of Theravance, including our ability to successfully realize the anticipated benefits of the acquisition;

•the extent to which our business may be adversely affected by pandemics or other health crises;

•global economic and political conditions, as well as social and political unrest in the locations where our or our strategic partners’ clinical trials are held, and the related impact on our business and the markets generally;

•unanticipated tax consequences in connection with the Redomicile Transactions (as defined below);

•the possibility that the Fast Track and Breakthrough Therapy designations for any of our or our strategic partners’ product candidates may not expedite regulatory review or approval;

•the U.S. Food and Drug Administration’s (the “FDA”) refusal to accept data from trials we or our strategic partners conduct outside the United States;

•disruptions at the FDA and other government agencies caused by funding shortages, global health concerns or changes implemented by the current U.S. Presidential administration;

•changes in regulations and customs, tariffs and trade barriers;

•the potential for our or our strategic partners’ product candidates to have undesirable side effects;

•the likelihood of broad market acceptance of our or our strategic partners’ product candidates;

•the ability to obtain Orphan Drug Designation or exclusivity for some or all of our or our strategic partners’ product candidates;

•our and our strategic partners’ ability to commercialize products outside of the United States;

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•the outcome of reimbursement decisions by third-party payors relating to our or our strategic partners’ products;

•our expectations with respect to the market opportunities for any product that we or our strategic partners develop;

•our and our strategic partners’ ability to pursue product candidates that may be profitable or have a high likelihood of success;

•our ability to use and expand our therapeutic platforms to build a pipeline of product candidates;

•our and our strategic partners’ ability to meet the requirements of ongoing regulatory review;

•the threat of product liability lawsuits against us or any of our strategic partners;

•changes in product candidate manufacturing or formulation that may result in additional costs or delay;

•the potential for non-U.S. governments to impose strict price controls;

•the risk of security breaches and incidents or data loss, which could compromise sensitive business or health information;

•current and future legislation that may increase the difficulty and cost of commercializing our or our strategic partners’ product candidates;

•economic, political, regulatory and other risks associated with international operations;

•our exposure to legal and reputational penalties as a result of any of our current and future relationships with various third parties;

•our and our strategic partners’ ability to comply with export control and import laws and regulations;

•our history of significant losses since inception;

•the potential dilution to our stockholders associated with any future financings;

•restrictions on our ability to seek financing, which may be imposed by future debt;

•unstable market and economic conditions;

•currency fluctuations and changes in currency exchange rates;

•our or a third party’s ability to successfully develop any companion diagnostic tests for our product candidates without significant delays;

•our and our strategic partners’ reliance on third-party manufacturers to produce our product candidate supplies and on other third parties to monitor and transport bulk drug substance and drug product;

•our and our strategic partners’ reliance on third parties to oversee clinical trials of our product candidates and, in some cases, maintain regulatory files for those product candidates;

•risks related to the manufacture of product candidates and difficulties in production;

•our and our strategic partners’ reliance on third parties for various operational and administrative aspects of our business including our reliance on third parties’ cloud-based software platforms;

•our and our strategic partners’ reliance on the performance of independent clinical investigators and contract research organizations (“CROs”);

•our ability to operate without infringing the patents and other proprietary rights of third parties;

•our ability to obtain and enforce patent protection for our or our strategic partners’ product candidates and related technology;

•our patents could be found invalid or unenforceable if challenged;

•our intellectual property rights may not necessarily provide us with competitive advantages;

•our potential involvement in expensive and time-consuming patent lawsuits;

•the risk that the duration of our patents will not adequately protect our competitive position;

•our ability to obtain protection under the Drug Price Competition and Patent Term Restoration Act of 1984 (the “Hatch-Waxman Amendments”) and similar non-U.S. legislation;

•our ability to protect the confidentiality of our proprietary information;

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•our ability to comply with procedural and administrative requirements relating to our patents;

•the risk of claims challenging the inventorship of our patents and other intellectual property;

•our dependency on the abilities of third parties to assert and defend our intellectual property rights for some of our or our strategic partners’ product candidates;

•patent reform legislation and court decisions can diminish the value of patents in general, thereby impairing our ability to protect our or our strategic partners’ products or product candidates;

•our ability to protect our intellectual property rights throughout the world;

•that we and our strategic partners will require FDA approval for any proposed product candidate names and any failure or delay associated with such approval may adversely affect our anticipated milestone or royalty revenues;

•our election to rely on certain reduced reporting and disclosure requirements available to smaller reporting companies may make our common stock less attractive to investors;

•the risk of employee misconduct including noncompliance with regulatory standards and insider trading;

•our and our strategic partners’ ability to market products in a manner that does not violate the law and subject us to civil or criminal penalties;

•potential adverse effects to our business from any non-compliance with laws regulating the protection of the environment and health and human safety;

•our ability to retain key executives and attract and retain qualified personnel;

•our ability to manage the evolution of our business strategy;

•our exposure to potential securities class action litigation; and

•the possibility that our share price and trading volume could decline if securities or industry analysts do not publish research or publish inaccurate or unfavorable research about our business.

Consequently, forward-looking statements should be regarded solely as our current plans, estimates and beliefs. You should not place undue reliance on forward-looking statements. We cannot guarantee future results, events, levels of activity, performance or achievements. We do not undertake and specifically decline any obligation to update, republish or revise forward-looking statements to reflect future events or circumstances or to reflect the occurrences of unanticipated events, except as required by law. Our Risk Factors are not guarantees that no such conditions exist as of the date of this report and should not be interpreted as an affirmative statement that such risks or conditions have not materialized, in whole or in part.

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this Quarterly Report on Form 10-Q, and although we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted a thorough inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and you are cautioned not to unduly rely upon these statements.

We own or have rights to trademarks, service marks or trade names that we use in connection with the operation of our business. In addition, our names, logos and website names and addresses are our service marks or trademarks. Our registered trademarks include Azymetric, Zymeworks, ZymeCAD, EFECT, ZymeLink and ProTECT. The other trademarks, trade names and service marks appearing in this Quarterly Report on Form 10-Q are the property of their respective owners. Solely for convenience, the trademarks, service marks, tradenames and copyrights referred to in this Quarterly Report on Form 10-Q are listed without the ©, ® and TM symbols, but we will assert, to the fullest extent under applicable law, our rights or the rights of the applicable licensors to these trademarks, service marks and tradenames.

We express all amounts in this Quarterly Report on Form 10-Q in U.S. dollars, except where otherwise indicated. References to “$” and “US$” are to U.S. dollars and references to “C$” are to Canadian dollars.

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PART I. FINANCIAL INFORMATION

Zymeworks Inc.

Index to Interim Condensed Consolidated Financial Statements (unaudited)

As of and for the three and nine months ended September 30, 2026