A Study Evaluating the Safety, Pharmacokinetics and Efficacy of Ipatasertib Administered in Combination With Rucaparib in Participants With Advanced Breast, Ovarian Cancer, and Prostate Cancer.

This is a study in participants with advanced breast, ovarian, or prostate cancer to investigate the dose, safety, pharmacokinetics, and preliminary efficacy of ipatasertib in combination with rucaparib. The study consists of two parts: a Dose-Escalation Phase (Part 1) in participants with previously treated advanced breast cancer, ovarian cancer, or prostate cancer and a Dose-Expansion Phase (Part 2) in participants with advanced prostate cancer who have had at least one line of prior therapy with second-generation androgen-receptor (AR)-targeted agents (e.g., abiraterone, enzalutamide, apalutamide).

There are two parts in the study. A Dose-Escalation Phase (Part 1) in participants with previously treated advanced breast cancer, ovarian cancer, or prostate cancer. There will be a 7-day run-in period with ipatasertib alone prior to Cycle 1, Day 1. After the completion of the ipatasertib run-in period, participants will begin Cycle 1, Day 1 of the ipatasertib and rucaparib combination treatment. Each cycle has 28 days. Participants will be split into 4 cohorts: Dose Level 1 group - 300 mg ipatasertib once daily (QD) + 400 mg rucaparib twice daily (BID), Dose Level 2a: 300 mg ipatasertib QD + 600 mg rucaparib BID, Dose Level 2b: 400 mg ipatasertib QD + 400 mg rucaparib BID, Dose Level 3: 400 mg ipatasertib QD + 600 mg rucaparib BID A Dose-Expansion Phase (Part 2) - The recommended dose identified in Part 1 (highest dose level of ipatasertib and rucaparib with an acceptable safety profile and less than one-third of participants experience a dose limiting toxicity) will be evaluated in participants with advanced prostate cancer who have had at least one line of prior therapy with second-generation androgen-receptor (AR)-targeted agents (e.g., abiraterone, enzalutamide, apalutamide). Enrollment in Cohort 3 in dose escalation phase was not opened as one-third of Dose Limiting Toxicity (DLT) evaluable participants receiving the highest dose of rucaparib in Cohort 2a experienced a DLT.