Phase 1 study of IMGN853, a folate receptor alpha (FRα)-targeting antibody-drug conjugate (ADC) in patients (Pts) with epithelial ovarian cancer (EOC) and other FRA-positive solid tumors.

5558 Background: IMGN853 (mirvetuximab soravtansine) is a FRα-targeting ADC comprising a FRα-binding antibody and potent maytansinoid, DM4. Methods: This Phase 1 trial is being conducted to determine safety, pharmacokinetics (PK), pharmacodynamics, maximum tolerated dose, recommended phase 2 dose (RP2D) and evidence of activity of IMGN853 in pts with EOC or other FRa-positive solid tumors. As previously reported, the occurrence of ocular adverse events (AEs) was associated with peak drug exposure and pt weight. Dosing by adjusted ideal body weight (AIBW) instead of total body weight (TBW) was implemented to decrease PK variability. Two dosing schedules are being evaluated; (A) once every 3 weeks and (B) Days 1, 8, and 15, every 4 weeks. Results: Fifty nine pts enrolled to dose escalation to date, 44 (30 TBW; 14 AIBW) pts in A, 16 (AIBW) in B. RP2D for A was determined to be 6.0 mg/kg, while dose finding in B continues. Exposure to IMGN853 increased with an increase in dose in a more than dose-proportional...