Vidutolimod (CMP-001) in Combination With Nivolumab for the Treatment of Metastatic Castration Resistant Prostate Cancer

Primary Objective: I. To evaluate the safety and tolerability of vidutolimod (CMP-001) in combination with nivolumab in patients with metastatic castration resistant prostate cancer. Secondary Objectives: I. To evaluate prostate-specific antigen (PSA) response rate. II.To evaluate PSA undetectable rate. III. To evaluate time to PSA progression according to PCWG3. IV. To evaluate the confirmed objective response rate (ORR) based on Response Evaluation Criteria in Solid Tumors (RECIST) version (v) 1.1. V. To evaluate the 1-year radiographic progression free survival (rPFS) according to PCWG3. VI. To determine the 1-year overall survival (OS). VII. To evaluate the confirmed ORR by immune-related RECIST (irRECIST). Exploratory Objective: I. To evaluate the effect of treatment on the following changes, and others: Ia. Numbers of CD8 T-cells in tumors; Ib. Dendritic cell activation status (CD80, CD86, CD40) in tissue biopsy; Ic. Tumor specific T-cells in the blood (human leukocyte antigen \[HLA\]-DR+/CD38+ with T-cell receptor \[TCR\] sequencing). OUTLINE: Patients receive vidutolimod subcutaneously (SC) on days 1 and 7 of cycle 1, intratumorally (IT) on day 14 of cycle 1 and days 1 and 14 of cycle 2, and then SC on day 1 of subsequent cycles. Patients also receive nivolumab intravenously (IV) over 30 minutes on days 1 and 14 of cycle 2 and on day 1 of subsequent cycles. Cycles of nivolumab repeat every 4 weeks for up to 24 months in the absence of disease progression or unacceptable toxicity. Cycles of vidutolimod repeat every 4 weeks for up to 6 months in the absence of disease progression or unacceptable toxicity. After completion of the study treatment, patients are followed up for 30 days and then every 12 weeks thereafter.