Avelumab Plus 2nd-generation ADT in African American Subjects With mCRPC

This is a nonrandomized, open-label trial of avelumab in subjects with metastatic castration-resistant prostate cancer (mCRPC) experiencing PSA or radiographic progression while receiving 2nd generation ADT (abiraterone / enzalutamide/ apalutamide or darolutamide). Metastases must be radiographically evident by whole body bone scintigraphy or CT/MRI scan. Thirteen African American subjects will be enrolled into the initial cohort. If at least one positive response (PSA decrease by \>50% and or radiographic per RECIST 1.1) is found, the study will be expanded to accrue a total of 27 patients. The trial will be conducted in accordance with Good Clinical Practices. Subjects enrolled in the study will receive avelumab 10 mg/kg every 2 weeks (Q2W) and continue their previously started 2nd generation ADT (abiraterone or enzalutamide). All subjects will undergo radiographic imaging assessments and PSA assessments to evaluate response to treatment at regular intervals. On study imaging will be assessed every 12 weeks. Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 will be adapted per the consensus guidelines of the Prostate Cancer Clinical Trials Working Group 3 (PCWG3) as described in Appendix A/B to account for the tumor progression patterns seen in bone metastases in prostate cancer. PSA will be obtained every 2 weeks with PSA progression assessed per PCWG3. Adverse events (AEs) will be monitored throughout the trial and graded in severity according to the guidelines outlined in the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version 4.03. Treatment with avelumab will continue until documented confirmed disease progression, unacceptable AEs, intercurrent illness that prevents further administration of treatment, Investigator's decision to withdraw the subject, subject discontinuation from the study, noncompliance with trial treatment or procedure requirements, subject receives 52 administrations of avelumab (approximately 2 years), or administrative reasons requiring the cessation of treatment. After the end of treatment, each subject will be followed for 30 days for AE monitoring (serious AEs will be collected for 90 days after the end of treatment or 30 days after the end of treatment if the subject initiates new anticancer therapy, whichever is earlier). Subjects who discontinue treatment for reasons other than disease progression will remain on study and continue to undergo study-related disease assessments until documented disease progression, initiation of a new non-study prostate cancer treatment, withdrawal of consent, or becoming lost to follow-up. All subjects will enter survival follow up, and will be contacted at their regularly scheduled clinic visit, or by telephone approximately every 6 months, until death or withdrawal of consent or end of study.