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.

Inclusion Criteria

• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1
• A life expectancy of at least 3 months
• Ability to swallow oral study drug
• Have adequate organ and marrow function as confirmed by the laboratory values listed below, obtained within 28 days prior to the first dose of study treatment:
• Bone marrow function assessments (without transfusion within 28 days prior to receipt of study treatment):
• ANC >= 1500 cells/uL (1.5 x 10^9/L) without granulocyte-colony stimulating factor support
• Platelet count >= 100.0 x 10^9/L
• Hemoglobin >= 9 g/dL (or 5.6 mmol/L)
• Chemistry panel assessments:
• AST and ALT = 3.0 g/dL
• Serum creatinine = 50 mL/min
• Fasting glucose = 6 months following the last dose of the platinum treatment administered) or platinum-resistant disease
• Have a CA-125 level that is > 2 x ULN
• Must have measurable disease by RECIST v1.1
• For patients with breast cancer (Part 1 only): must be human epidermal growth factor receptor 2 negative (HER2-) (estrogen receptor [ER]/progesterone positive or negative):
• ER/progesterone-positive patients must have received and progressed on at least one endocrine therapy (adjuvant or metastatic)
• ER/progesterone-negative/HER2- (triple-negative breast cancer [TNBC]) patients must have received at least one prior line of chemotherapy for metastatic breast cancer
• Must not have received more than two prior lines of chemotherapy for metastatic breast cancer
• Must have measurable disease by RECIST v1.1

For patients with prostate cancer:

• Adenocarcinoma of the prostate without small cell or neuroendocrine features
• Surgical or medical castration with testosterone = 1 week apart, with second result >= 1 ng/mL) or radiographic progression with or without PSA progression
• Must have received at least one prior line of second-generation androgen receptor targeted therapy (e.g., abiraterone, enzalutamide, apalutamide)
• Patients with prostate cancer must have either measurable disease by RECIST v1.1 or bone lesions by bone scan, or both.
• Submission of a formalin-fixed, paraffin-embedded (FFPE) tumor tissue block or a minimum of 12 freshly cut, unstained, serial tumor slides from the most recently collected tumor tissue for central molecular analysis (retrospective NGS testing for HR and PI3K-AKT pathway status and for other protocol-mandated secondary and exploratory assessments). Cytologic or fine needle aspirate samples are not acceptable. Tumor tissue from bone metastases is not acceptable.
• For men and women of child bearing potential: agreement to remain abstinent or use protocol defined contraceptive measures during the treatment period and for at least 28 days after the last dose of ipatasertib,or 6 months after the last dose of rucaparib, whichever occurs later

Exclusion Criteria

• Pregnant or breastfeeding, or intending to become pregnant during the study or within 28 days after the final dose of ipatasertib or 6 months after the final dose of rucaparib
• Prior treatment with a PARP inhibitor, AKT inhibitor, or PI3K inhibitor
• Treatment with investigational therapy within 14 days prior to initiation of study drug
• Symptomatic and/or untreated CNS metastases
• Uncontrolled tumor-related pain
• Non-study-related minor surgical procedures = 10 mg of prednisone per day or an equivalent dose of other anti-inflammatory corticosteroids or immunosuppressants for a chronic disease
• History of another malignancy within 5 years prior to randomization, except for either adequately treated non-melanomatous carcinoma of the skin, adequately treated melanoma in situ, adequately treated non-muscle-invasive urothelial carcinoma of the bladder (Tis, Ta, and low-grade T1 tumors), or other malignancies where the patient has undergone potentially curative therapy with no evidence of disease and are deemed by the treating physician to have a recurrence rate of < 5% at 5 years.
• History of clinically significant cardiova