A Study Evaluating The Safety, Efficacy and Pharmacokinetics Of Ipatasertib In Combination With Atezolizumab And Docetaxel In Metastatic Castration-Resistant Prostate Cancer (mCRPC).

Inclusion Criteria: * Ability to comply with the study protocol. * Adenocarcinoma of the prostate without small-cell or neuroendocrine features. * Metastatic disease that cannot be treated with curative intent. * Surgical or medical castration with testosterone serum level \< 50 ng/dL (1.7 nM). * For participants treated with luteinizing hormone-releasing hormone analogs, initiation therapy \>= 4 weeks prior to the first dose of study treatment and continued therapy throughout study treatment. * Progression of Prostate Cancer. * Receipt of at least one prior line of second generation AR-targeted therapy. * For participants in Part A of study: measurable visceral disease or measurable extrapelvic adenopathy per RECIST v1.1. * For participants in Part B of study: either measurable visceral disease or measurable extrapelvic adenopathy by RECIST v1.1 or bone lesions by bone scan, or both. * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1. * Life expectancy of \>= 3 months. * Ability to swallow oral study drug. * Adequate organ and bone marrow function. * Resolved or stabilized toxicities resulting from previous therapy to Grade 1 (except for alopecia and neuropathy). * For men: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive measures and agreement to refrain from donating sperm. Exclusion Criteria: * Prior treatment with an AKT, PI3K, or mTOR inhibitor. * Prior treatment with radium or other therapeutic radiopha…