Azenosertib (ZN-c3) (oral inhibitor of WEE1) w/ multiple chemo

May 21, 2026 — Zentalis Pharmaceuticals (Nasdaq: ZNTL) announced it will present Part 1 data from its Phase 1b, open-label MUIR trial (ZN-c3-002; NCT04516447) at the 2026 ASCO Annual Meeting (poster June 1, 2026) evaluating the investigational WEE1 inhibitor azenosertib plus paclitaxel in platinum-resistant ovarian cancer (PROC).

With a December 1, 2025 data cutoff, 46 heavily pre-treated PROC patients (all previously received paclitaxel) received azenosertib across four dose cohorts plus paclitaxel 80 mg/m². Across cohorts, the regimen achieved ORR 39.1% (95% CI 25.1–54.6), CBR 58.7% (42.2–73.0), median DOR 5.6 months (5.6–9.2), and median PFS 7.3 months (3.7–7.5). In the 250 mg QD intermittent 5-days-on/2-days-off cohort (n=12), ORR was 50% (including 1 CR) and median DOR 9.2 months.

Safety was described as manageable; common TRAEs included fatigue (60.9%), anemia (58.7%), nausea (52.2%), and neutropenia (50.0%). Grade ≥3 neutropenia occurred in 30.4% and anemia in 19.6%; one sepsis death was assessed as related to azenosertib. Clinically, results support further evaluation of azenosertib–taxane combinations beyond Cyclin E1 biomarker status.