UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): November 17, 2025

Zymeworks Inc.

(Exact name of registrant as specified in its charter)

Delaware

001-41535

88-3099146

(State or other jurisdiction

of incorporation)

(Commission

File Number)

(IRS Employer

Identification No.)

108 Patriot Drive, Suite A

Middletown, Delaware

19709

(Address of principal executive offices)

(Zip Code)

(302) 274-8744

(Registrant’s telephone number, including area code)

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading
Symbol(s)

Name of each exchange

on which registered

Common Stock, par value $0.00001 per share

ZYME

The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8.01

Other Events.

On November 17, 2025, Zymeworks Inc. (the “Company”) issued a press release announcing positive topline results from the Phase 3 HERIZON-GEA-01 trial evaluating Ziihera^® (zanidatamab-hrii) in combination with chemotherapy, with or without the PD-1 inhibitor Tevimbra^® (tislelizumab), as a first-line treatment for HER2-positive (HER2+) locally advanced or metastatic gastroesophageal adenocarcinoma, including cancers of the stomach, gastroesophageal junction, and esophagus. A copy of this press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Item 9.01

Financial Statements and Exhibits.

(d) Exhibits


Exhibit No.		Description

99.1		Press Release, dated November 17, 2025

104		Cover Page Interactive Data File (embedded as Inline XBRL document).

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

ZYMEWORKS INC.

(Registrant)

Date: November 17, 2025

/s/ Kenneth Galbraith

Name:

Title:

Kenneth Galbraith

Chair, President and Chief Executive Officer

Zymeworks Inc. 8-K