Zymeworks Appoints Leone Patterson as Chief Business and Financial Officer Vancouver, British Columbia (

Zymeworks Appoints Leone Patterson as Chief Business and Financial Officer

Vancouver, British Columbia (July 25, 2024) Zymeworks Inc. (Nasdaq: ZYME), a clinical-stage biotechnology company developing a diverse pipeline

of novel, multifunctional biotherapeutics to improve the standard of care for difficult-to-treat diseases, today announced the appointment of Leone Patterson as

Executive Vice President, and Chief Business and Financial Officer, effective September 1, 2024.

After an extensive search, we are delighted

to have Leone Patterson join us at this exciting time as we plan for our next stage of growth and development at Zymeworks, said Kenneth Galbraith, Chair and CEO of Zymeworks. She brings more than 20 years of public company biotech

experience with a proven track record of guiding strategy, finance, operations, and governance through multiple phases of growth, planning and executing successful financial strategies. Ms. Patterson has the financial leadership qualities to

support Zymeworks as we continue to make progress in achieving our 5 by 5 goal of having five novel antibody-drug conjugates or novel T cell engagers in clinical studies by 2026, and progress product candidates from our ADVANCE R&D

programs into clinical studies by 2027 and beyond.

I am very pleased to be joining Zymeworks as the Company plans for many important

milestones in the months and years ahead. I look forward to working collaboratively with the experienced leadership team in maximizing the value of the rapidly expanding pipeline and addressing many critical areas of unmet medical needs for patients

with difficult-to-treat cancers and other serious diseases, said Ms. Patterson.

Prior to joining Zymeworks, Ms. Patterson served as Chief Financial and Business Officer at Tenaya Therapeutics where she led corporate finance, investor

relations, corporate communications, strategy and business development teams as well as other operational functions. She previously held leadership positions at Adverum Biotechnologies including Chief Financial Officer, President, Chief Executive

Officer and Director. She also has held senior finance positions at Diadexus, Transcept, Exelixis, Novartis, and Chiron. Earlier in her career she worked in the audit practice of KPMG.

Ms. Patterson currently serves on the board of directors of Nkarta, Inc. and Oxford Biomedica, both publicly-held companies. She earned a B.S. in

business administration and accounting from Chapman University and an executive MBA from St. Mary s College. Ms. Patterson is also a Certified Public Accountant (inactive status).

Ms. Patterson s appointment builds on the Company s continued focus on strengthening its leadership in the biopharmaceutical industry and

expanding its pipeline of pharmaceutical candidates with the potential to make a significant difference in the lives of patients around the world with difficult-to-treat

other diseases. She will be responsible for assisting with the development of Zymeworks long-term financial strategy, providing leadership surrounding financing and capital strategies and

supporting strategic business decisions. She will be based in the new Zymeworks location in Redwood City, California.

About Zymeworks Inc.

Zymeworks is a global clinical-stage biotechnology company committed to the discovery, development, and commercialization of novel, multifunctional

biotherapeutics. Zymeworks mission is to make a meaningful difference in the lives of people impacted by difficult-to-treat cancers and other diseases. The

Company s complementary therapeutic platforms and fully integrated drug development engine provide the flexibility and compatibility to precisely engineer and develop highly differentiated antibody-based therapeutic candidates. Zymeworks

engineered and developed zanidatamab, a HER2-targeted bispecific antibody using the Company s proprietary Azymetric technology. Zymeworks has entered into separate agreements with

BeiGene, Ltd. (BeiGene) and Jazz Pharmaceuticals Ireland Limited (Jazz), granting each exclusive rights to develop and commercialize zanidatamab in different territories. Zanidatamab is currently being evaluated in multiple global clinical trials as

a potential best-in-class treatment for patients with HER2-expressing cancers. A Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA)

seeking accelerated approval for zanidatamab as a treatment for previously-treated, unresectable, locally advanced, or metastatic HER2-positive biliary tract cancer (BTC) has been accepted and granted Priority Review. A BLA has also been accepted

for review by the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) in China. If approved, zanidatamab would be the first HER2-targeted treatment specifically approved for BTC in the U.S. and China. Zymeworks is

rapidly advancing a deep pipeline of product candidates based on its experience and capabilities in both antibody-drug conjugates and multispecific antibody therapeutics across multiple novel targets in indications that represent areas of

significant unmet medical need. In addition to Zymeworks wholly owned pipeline, its therapeutic platforms have been further leveraged through strategic partnerships with global biopharmaceutical companies. For information about Zymeworks,

visit www.zymeworks.com and follow @ZymeworksInc on X.

Cautionary Note Regarding Forward-Looking Statements

This press release includes forward-looking statements or information within the meaning of the applicable securities legislation, including

Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements in this press release include, but are not limited to, statements that relate to

Ms. Patterson s anticipated appointment date; Ms. Patterson s expected contributions to Zymeworks strategic goals; potential therapeutic effects and commercial potential of zanidatamab and Zymeworks other product

candidates; Zymeworks clinical development of its product candidates and enrollment in its clinical trials; the ability to advance product candidates into later stages of development; and other information that is not historical information.

When used herein, words such as plan , believe , expect , may , continue , anticipate , potential , will , progress , and similar expressions are

intended to identify forward-looking statements. 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. All forward-looking statements are based

upon Zymeworks current expectations and various assumptions. Zymeworks believes there is a reasonable basis for its expectations and beliefs, but they are inherently uncertain. Zymeworks

may not realize its expectations, and its beliefs may not prove correct. Actual results could differ materially from those described or implied by such forward-looking statements as a result of various factors, including, without limitation:

clinical trials may not demonstrate safety and efficacy of any of Zymeworks or its collaborators product candidates; any of Zymeworks or its partners product candidates may fail in development, may not receive required

regulatory approvals, or may be delayed to a point where they are not commercially viable; regulatory agencies may impose additional requirements or delay the initiation of clinical trials; the impact of new or changing laws and regulations; market

conditions; and the factors described under Risk Factors in Zymeworks quarterly and annual reports filed with the Securities and Exchange Commission (copies of which may be obtained at www.sec.gov and www.sedar.com). Although

Zymeworks believes that such forward-looking statements are reasonable, there can be no assurance they will prove to be correct. Investors should not place undue reliance on forward-looking statements. The above assumptions, risks and uncertainties

are not exhaustive. Forward-looking statements are made as of the date hereof and, except as may be required by law, Zymeworks undertakes no obligation to update, republish, or revise any forward-looking statements to reflect new information, future

events or circumstances, or to reflect the occurrences of unanticipated events.