A Study of Olaparib and Durvalumab in Prostate Cancer

Inclusion Criteria: * Willing and able to provide written informed consent and HIPAA authorization for the release of personal health information. A signed informed consent must be obtained before screening procedures are performed. NOTE: HIPAA authorization may be either included in the informed consent or obtained separately. * Males 18 years of age and above * Body weight \> 30kg * History of radical prostatectomy * Histologically confirmed prostate cancer with progressive disease defined as: * Rising PSA (50% or more increase to a level of 0.50 ng/mL or more, based on at least 3 PSA determinations obtained at least 1 week apart). The 50% rise in PSA is across the 3 determinations, and these determinations do not need to be sequential. * PSA doubling time of \</= 9 months as calculated according to the Memorial Sloan Kettering Cancer Center nomogram * No evidence of metastatic disease on conventional imaging (CT/MRI and bone scan). However, subjects with pelvic and/or retroperitoneal nodes \< 2cm in the short axis will be permitted on study, as they are considered not to have definitive metastases. (Note: Metastatic disease on investigational imaging, Prostate Specific Membrane Antigen-targeted (PSMA) PET, PET-choline, or other novel PET tracers who do not have evidence of metastatic disease using conventional imaging (CT/MRI, bone scan) are allowed.) * Molecular evidence of DDR deleterious mutations (somatic or germline), including BRCA1, BRCA2, ATM, CHEK2, FANCA, RAD5…