Zymeworks Inc

REPORT OF INDEPENDENT REGISTERED

PUBLIC ACCOUNTING FIRM

To the Stockholders and Board of Directors

Zymeworks Inc.:

Opinion on the Consolidated Financial Statements

We have audited the accompanying consolidated balance sheets of Zymeworks Inc. and subsidiaries (the Company) as of December 31, 2024 and 2023, the related consolidated statements of (loss) income and comprehensive (loss) income, changes in stockholders’ equity, and cash flows for each of the years in the three‑year period ended December 31, 2024, and the related notes (collectively, the consolidated financial statements). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2024 and 2023, and the results of its operations and its cash flows for each of the years in the three‑year period ended December 31, 2024, in conformity with U.S. generally accepted accounting principles.

Basis for Opinion

These consolidated financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on these consolidated financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the consolidated financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of a critical audit matter does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Revenue recognition from drug supply for ongoing studies from Jazz Pharmaceuticals Ireland Limited (Jazz)

As discussed in Note 11 to the consolidated financial statements, the Company recognized revenue from Jazz related to drug supply for ongoing studies of $19,228 thousand for the year ended December 31, 2024. As discussed in Note 2, amounts receivable by the Company for the provision of drugs to clinical trials on behalf of the customer are recognized in revenue at a point in time when title to drugs has transferred to the customer, which generally occurs upon shipment or delivery, depending on contractual terms.

We identified the sufficiency of audit evidence relating to revenue recognition from drug supply for ongoing studies with Jazz as a critical audit matter. Subjective auditor judgment was required to evaluate the sufficiency of audit evidence obtained related to the Company’s revenue from drug supply for ongoing studies because of the involvement of clinical research support organizations in tracking and fulfilment of the drugs provided across multiple locations.

The following are the primary procedures we performed to address this critical audit matter. We evaluated the design and implementation of internal controls over the Company’s revenue recognition process. We obtained a confirmation from the customer on invoices billed related to goods and services provided for the year ended December 31, 2024 and agreed the quantity of drugs invoiced to the Company’s records. We assessed the recorded revenue by selecting a sample of revenue transactions and comparing the amounts recognized for consistency with relevant underlying documentation. We evaluated the sufficiency of audit evidence obtained over revenue by assessing the results of the procedures performed, including the appropriateness of the nature and extent of such evidence.

/s/KPMG LLP

Chartered Professional Accountants

We have served as the Company’s auditor since 2015.

Vancouver, Canada

March 5, 2025