Abiraterone Acetate and Prednisone With or Without Veliparib in Treating Patients With Metastatic Castration-Resistant Prostate Cancer

PRIMARY OBJECTIVES: I. To evaluate the role of v-ets erythroblastosis virus E26 oncogene (ETS) gene fusion as a predictive biomarker for response to hormone therapy (abiraterone \[abiraterone acetate\]) alone or hormone therapy plus poly adenosine diphosphate-ribose polymerase 1 (PARP-1) targeted therapy (ABT-888 \[veliparib\]) in patients with metastatic castration resistant prostate cancer. II. To evaluate whether the addition of PARP-1 targeted therapy is superior to hormone therapy alone based on ETS gene fusion status. SECONDARY OBJECTIVES: I. Rate of prostate-specific antigen (PSA) declines. II. Objective response rate. III. Progression-free survival. IV. Evaluate the qualitative and quantitative toxicity of abiraterone acetate with and without ABT-888. TERTIARY OBJECTIVES: I. To determine the concordance in fusion status among prostate cancer samples from the primary site, biopsied metastasis, and circulating tumor cells (CTCs). II. To assess if ETS fusion status in the CTCs, at baseline, 12 weeks, and disease progression (or when off study) is associated with response to therapy. III. To evaluate if the number of CTCs, as well as the expression levels of androgen receptor, RAD51 recombinase (RAD51), and gamma-H2A histone family, member X (H2aX) foci in the CTCs at baseline, at 12 weeks, and at disease progression in all patients is associated with response to therapy. IV. To determine the role of phosphatase and tensin homolog (PTEN) loss as a predictive biomarker of response to abiraterone, alone or in combination with ABT-888. V. To determine the role of PARP1 activity as a predictive biomarker of response to abiraterone, alone or in combination with ABT-888. VI. To perform next-generation sequencing for discovery of novel gene fusions in prostate cancers negative for ETS fusions. VII. To perform germline single nucleotide polymorphism (SNP) analysis of genes involved in hormone synthesis, transport, binding, metabolism, and degradation for discovery of novel SNPs predictive of response to abiraterone, alone or in combination with ABT-888. VIII. To determine if ETS fusion ribonucleic acid (RNA) levels in blood are predictive of response to abiraterone, alone or in combination with ABT-888. OUTLINE: Patients are randomized to 1 of 2 treatment arms. ARM I: Patients receive abiraterone acetate orally (PO) once daily (QD) and prednisone PO twice daily (BID) on days 1-28. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. ARM II: Patients receive veliparib PO BID on days 1-28. Patients also receive abiraterone acetate PO QD and prednisone PO BID on day 1 (day 8 of course 1). Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up every 6 months for up to 2 years.