ZW191 (FRα-targeted ADC) posts 52% unconfirmed ORR in platinum-resistant ovarian/endometrial cancers (Phase 1)

ZW191 is a folate receptor α (FRα)-targeting antibody–drug conjugate (ADC) evaluated in the ongoing first-in-human ZWI-ZW191-101 Phase 1/2 study (NCT06555744); this Part 1 dose-escalation readout (data cut: Dec 1, 2025) treated heavily pretreated recurrent platinum-resistant ovarian cancer (PROC), endometrial cancer (EC), or NSCLC patients regardless of FRα expression with IV ZW191 Q3W across 1.6–11.2mg/kg (n=51; median 3 prior lines). In 48 response-evaluable patients, unconfirmed ORR was 52% overall, with activity reported even in FRα low/negative tumors; across 6.4–9.6mg/kg, unconfirmed ORR was 61% in OC and 57% in EC (time to response 6 weeks), which would be well above typical single-agent non-platinum chemo benchmarks in PROC (ORR ~4%–13%) and above the ~32% confirmed ORR seen with the FRα-high ADC mirvetuximab soravtansine in SORAYA (notably FRα-selected, not “all-comers”). Grade ≥3 TRAEs were mainly hematologic—neutropenia 18%, anemia 10%, thrombocytopenia 6%—with 67% still on treatment at cutoff; confirmed ORR, DOR, and PFS are pending, and 6.4mg/kg and 9.6mg/kg Q3W are moving into Part 2a dose optimization.