A Combination Study of Rucaparib and Atezolizumab in Participants With Advanced Gynecologic Cancers and Triple-Negative Breast Cancer

Atezolizumab 1200 mg (equivalent to an average body weight-based dose of 15 milligrams per kilogram \[mg/kg\]) will be administered by IV infusion once every 3 weeks, corresponding to a 21-day treatment cycle. Participants will receive atezolizumab starting on Cycle 1, Day 1. Participants deriving clinical benefit will be allowed to continue on study treatment until the absence of unacceptable toxicity or compelling evidence of disease progression.

The starting dosage level of rucaparib for Part 1 is 400 mg PO BID during a 21-day treatment cycle. During Part 1, the rucaparib doses were increased up to a maximum of 600 mg PO BID using a standard 3 + 3 dose escalation. RP2D was identified as 600 mg BID. During Part 2 of the study, rucaparib will be dosed at the RP2D determined in Part 1. Participants in Part 1 of the study will receive rucaparib starting on Cycle 1, Day 1. During Part 2, participants will receive rucaparib monotherapy during a 21-day run-in period. After completion of the rucaparib run-in period and the first on-treatment biopsy between Days 15 and 21 of the run-in period, participants will begin Cycle 1, Day 1 of the rucaparib. Participants deriving clinical benefit will be allowed to continue on study treatment until the absence of unacceptable toxicity or compelling evidence of disease progression.