Zymeworks (NASDAQ: ZYME) ends ZW171 early-stage cancer trial

Rhea-AI Filing Summary

Zymeworks Inc. has decided to voluntarily discontinue clinical development of ZW171, a T cell engager targeting gynecological, thoracic, and digestive system cancers. The decision follows completion of the planned dose-escalation cohorts in a Phase 1 trial in patients with ovarian cancer and non-small cell lung cancer, where a maximum tolerated dose was established. After reviewing these results, the company concluded that further dose evaluation in the current trial was unlikely to support a benefit-risk profile consistent with the desired monotherapy target product profile. The decision was announced via press release furnished as an exhibit.

Positive

• None.

Negative

• ZW171 clinical program discontinued, removing an early-stage oncology asset after Phase 1 dose-escalation results did not support the desired monotherapy benefit-risk profile.

Insights

Biotech equity analyst

Zymeworks is stopping development of early-stage cancer drug ZW171 after Phase 1 dose-escalation results.

Zymeworks is voluntarily ending clinical development of ZW171, a T cell engager intended for several solid tumors. This move comes after completing the planned dose-escalation portion of a Phase 1 trial in ovarian cancer and non-small cell lung cancer and defining a maximum tolerated dose. Management determined that continuing dose evaluation in this trial was unlikely to deliver the benefit-risk balance needed for a standalone therapy.

Stopping an early program usually reflects a data-driven pipeline prioritization rather than a broad platform issue, but it does reduce the company’s near-term optionality around this asset. The filing does not provide additional financial or pipeline context, so the impact depends on how central ZW171 was within the overall portfolio, which would be clarified in subsequent company communications.

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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): September 2, 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 7.01 Regulation FD Disclosure.

On September 2, 2025, Zymeworks Inc. (the “Company”) issued a press release announcing the Company’s decision to voluntarily discontinue clinical development of ZW171. A copy of this press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K.

The information provided under this Item 7.01 (including Exhibit 99.1 attached hereto) is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing.

Item 8.01 Other Events.

As announced on September 2, 2025, the Company made the decision to voluntarily discontinue clinical development of ZW171, a T cell engager designed to target gynecological, thoracic, and digestive system cancers. The decision to discontinue clinical development of ZW171 was based on completion of the planned cohorts of the dose escalation portion of the Phase 1 trial of ZW171 in patients with ovarian cancer and non-small cell lung cancer. After completing the planned dose escalation cohorts and establishing a maximum tolerated dose, the Company determined that further dose evaluation in the current trial would be unlikely to support a benefit-risk profile consistent with the desired monotherapy target product profile.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.		Description
99.1		Press Release, dated September 2, 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: September 2, 2025				By:		/s/ Leone Patterson
				Name:		Leone Patterson
				Title:		Executive Vice President, Chief Business Officer and Chief Financial Officer

FAQ

What did Zymeworks Inc. (ZYME) announce regarding ZW171?

Zymeworks Inc. announced that it has made the decision to voluntarily discontinue clinical development of ZW171, as disclosed in a current report and related press release.

What is ZW171 and what cancers was it targeting for ZYME?

ZW171 is described as a T cell engager designed to target gynecological, thoracic, and digestive system cancers, with the Phase 1 trial including patients with ovarian cancer and non-small cell lung cancer.

Why is Zymeworks discontinuing clinical development of ZW171?

After completing the planned dose-escalation cohorts in the Phase 1 trial and establishing a maximum tolerated dose, Zymeworks determined that further dose evaluation in the current trial would be unlikely to support a benefit-risk profile consistent with the desired monotherapy target product profile.

What stage of development had ZW171 reached before ZYME stopped the program?

ZW171 had reached the dose-escalation portion of a Phase 1 clinical trial in patients with ovarian cancer and non-small cell lung cancer before the company decided to discontinue its clinical development.

How did Zymeworks communicate the ZW171 decision to investors?

Zymeworks issued a press release on September 2, 2025, announcing the decision to discontinue ZW171 clinical development, and furnished that release as Exhibit 99.1 to a current report on Form 8-K.

Does the ZW171 update affect other Zymeworks programs?

The disclosure focuses specifically on the decision to discontinue clinical development of ZW171 and does not describe any changes to other Zymeworks programs.