Clinical Trial Results

Zymeworks Inc. (NASDAQ:ZYME) disclosed Phase 1 data for its antibody‑drug conjugate ZW191, which targets folate receptor alpha (FRα), at the European Society for Medical Oncology Gynaecological Cancers Congress 2026. The study enrolled patients with platinum‑resistant ovarian cancer and endometrial cancer. Across all dose levels, the confirmed objective response rate (ORR) was 78.6% in FRα‑positive tumors and 47.4% in FRα‑negative tumors. In the overall platinum‑resistant ovarian cancer cohort, the confirmed ORR was 58.8% across all doses and rose to 65.2% within the 6.4‑9.6 mg/kg dose range. Disease control rates (DCR) reached 100% in FRα‑positive patients and 89.5% in FRα‑negative patients. Among endometrial cancer patients with FRα‑negative tumors, the confirmed ORR was 40% and DCR 80% across all evaluated doses. The median duration of response had not been reached as of the March 9 2026 data cutoff, and median progression‑free survival (PFS) was 7.6 months across both ovarian and endometrial cohorts.

Safety Profile

Treatment‑emergent adverse events (TEAEs) were reported in 98% of participants, with grade 3 or higher events occurring in 55% of patients. The most frequent grade ≥ 3 events were neutropenia (24%), anemia (20%) and thrombocytopenia (12%). Serious adverse events were observed in 35% of the cohort, and 20% of patients discontinued treatment due to adverse events.

Study Design and Enrollment

The company completed enrollment in Part 2a of the study, randomising approximately 60 platinum‑resistant ovarian cancer patients to receive either 6.4 mg/kg or 9.6 mg/kg of ZW191 every three weeks.

Financial Highlights

In the first quarter of 2026, Zymeworks reported total revenue of $2.4 million, a 91.1% decline from the comparable quarter in 2025, reflecting the absence of non‑recurring clinical milestone payments that were present in the prior year. The company noted potential future milestone payments of $440 million linked to its pipeline. Concurrently, Zymeworks announced a new share repurchase programme authorising the buyback of up to $125 million of common stock and terminated its previous buyback programme.

Analyst Coverage

Truist Securities initiated coverage of Zymeworks with a Buy rating and a price target of $28 per share. H.C. Wainwright maintained its Buy rating and set a price target of $46 per share following the release of Phase 3 trial results for a partner’s drug candidate.

Overall Significance

The Phase 1 data demonstrate robust anti‑tumour activity, particularly in FRα‑positive ovarian cancer, while safety findings are consistent with the class of antibody‑drug conjugates. The sharp revenue decline underscores the company’s reliance on milestone‑driven cash flows, but the newly authorised $125 million buyback reflects confidence in balance‑sheet strength. Analyst initiation and continued Buy ratings suggest market optimism despite near‑term revenue weakness.