A total of 18 pts were enrolled in three dose cohorts: gedatolisib 110 mg weekly cofetuzumab pelidotin 1.40 mg/kg every 3 weeks (n=4), 180 mg, 1.40 mg/kg (n=3), and 180 mg, 2.80 mg/kg (n=11). Nausea, anorexia, fatigue, and mucositis were common but rarely reached grade 3 severity. Myelosuppression was uncommon. ORR was 16.67% (3/18). An additional 3 pts had stable disease (of these 2 had stable disease for>18 weeks); CB18 was 27.80%. Median PFS was 2.00 months (95% confidence interval for PFS: 1.20-6.20). Pts with clinical benefit were enriched with genomic alterations in the PI3K and PTK7 pathways.

The most common, treatment-related adverse events for PF-06647020 administered every 3 weeks were nausea, alopecia,fatigue, headache, neutropenia, and vomiting (45%); 25% of patients had grade 3 neutropenia. Two patients experienced doselimiting toxicities (grade 3 headache and fatigue) at the highest every 3 weeks dose evaluated. The recommended phase II dose was 2.80 mg/kg every 3 weeks. The overall safety profile observed with PF-06647020 administered every 2 weeks was similar to that of the every 3 weeks regimen. Systemic exposure for the ADC and total antibody generally increased in a dose-proportional manner. Antitumor activity was observed in treated patients with overall objective response rates of 27.00% in ovarian cancer (n=63), 19% in NSCLC (n=31), and 21% in TNBC (n=29).