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 that the first patient has been dosed in the company's first-in-human Phase 1 trial (NCT06555744) to evaluate the safety and tolerability of the investigational therapy ZW191 in the treatment of advanced folate receptor-⍺ (FR⍺)-expressing solid tumors including ovarian, endometrial, and non-small cell lung (NSCLC) cancers.

"Our team is excited to initiate this important clinical trial to assess the safety and tolerability of ZW191, our first antibody-drug conjugate utilizing ZD06519, our novel proprietary payload, in patients with difficult-to-treat cancers," said Jeff Smith, M.D., FRCP, Executive Vice President and Chief Medical Officer at Zymeworks. "This global study represents a significant milestone in our mission to bring innovative and urgently needed therapies to patients in need. This announcement also follows the recent initiation of our Phase 1 trial of ZW171, marking an additional important step forward in advancing the many promising therapies in our wholly-owned pipeline."

FRα is found in ~75% of high-grade serous ovarian carcinomas1 and ~70% of lung adenocarcinomas2. In data presented at the American Association for Cancer Research (AACR) Annual Meeting in 2024, ZW191 was associated with greater anti-tumor activity compared to benchmark in FRα-expressing tumor models and was well-tolerated in cynomolgus monkeys up to 60 mg/kg3.

The Phase 1 trial is a two-part, multi-center, global study that aims to enroll 145 adult patients with advanced FR⍺-expressing cancers. The Company expects to enroll patients at investigator sites in North America, Europe, and the Asia-Pacific region. Part one of the study will evaluate the safety and tolerability of ZW191 and involve dose escalation in patients with advanced ovarian, endometrial, and NSCLC cancers, with secondary endpoints assessing pharmacokinetics and confirmed objective response rate. Part two of the study will further evaluate safety and explore the potential anti-tumor activity of ZW191.