Apalutamide, Abiraterone Acetate, and Prednisone in Treating Participants With Metastatic Castration Resistant Prostate Cancer

PRIMARY OBJECTIVE: I. To assess the radiographic progression free survival (PFS) of men with metastatic castration resistant prostate cancer (mCRPC) who are selected for treatment based on positive biomarker signature. SECONDARY OBJECTIVES: I. Safety. II. Composite progression free survival (PFSc) defined by Prostate Cancer Working Group 2 (PCWG2) (radiographic progression, prostate specific antigen \[PSA\] progression, or clinical deterioration). III. Overall survival. IV. Exploratory biomarker analyses. V. Measures of prostate specific antigen (PSA) decline and associations with outcome. VI. Radiologic response by PCWG2 criteria. VII. Measures of circulating tumor cell (CTC) and conversion to undetectable and/or favorable \< 5. OUTLINE: Participants receive abiraterone acetate orally (PO) once daily (QD), apalutamide PO QD, and prednisone PO QD on days 1-28. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity. After completion of study treatment, participants are followed up for up to 16 months.