Adenosine Receptor Antagonist Combination Therapy for Metastatic Castrate Resistant Prostate Cancer

General Inclusion Criteria:

1. Male participants; age ≥ 18 years
2. Metastatic castrate-resistant prostate cancer while on anti-androgen treatment with castrate levels of testosterone (≤1.7 nanomoles per liter [nmol/L] or 50 nanograms per deciliter [ng/dL])
3. Measurable or non-measurable disease as per radiographic evaluation
4. Participants with measurable disease may require a fresh tumor biopsy at study entry
5. Eastern Cooperative Oncology Group (ECOG) Performance status of 0 or 1
6. Life expectancy of at least 3 months
7. Adequate hematologic and end-organ function
8. Human immunodeficiency virus (HIV), Hepatitis B, and C test results negative prior to first study treatment

Inclusion Criteria for Participants receiving an enzalutamide-containing treatment

Disease progression after prior treatment with abiraterone

Inclusion Criteria for Participants receiving a docetaxel-containing treatment

Disease progression after prior androgen synthesis inhibitor therapy

Inclusion Criteria for all other Participants

Disease progression after prior androgen synthesis inhibitor treatment and up to 2 prior lines of taxane chemotherapy

General Exclusion Criteria:

1. Prior treatment with immune checkpoint blockade therapy
2. Prior anticancer treatment including approved agents, systemic radiotherapy, or investigational therapy, within 2-4 weeks prior first study treatment
3. Corrected QT interval (QTc) ≥480 msec using Fredericia's QT correction formula (based on an average of triplicate recordings)
4. Prior allogeneic stem cell or solid organ transplantation
5. Prior treatment with drugs that stimulate the immune system within 4 weeks prior to first study treatment
6. Prior treatment with drugs that suppress the immune system within 2 weeks prior to first study treatment
7. Received a live, attenuated vaccine within 4 weeks prior to first study treatment, or may need to receive a vaccine during study treatment
8. Presence of metastases in the brain or cancer spreading into the cerebrospinal fluid - CSF (leptomeningeal disease)
9. Prior pulmonary fibrosis, pneumonia, or pneumonitis
10. Cancer other than prostate within 2 years prior to study entry, except for some cancers with a low risk of spreading like non-melanoma skin
11. Prior treatment with an agent targeting the adenosine pathway
12. No oral or IV antibiotics within 2 weeks prior to first study treatment
13. No severe infection within 4 weeks prior to first study treatment
14. No clinically significant cardiac disease
15. Inability to swallow medications

Exclusion Criteria for Participants receiving an enzalutamide-containing treatment

1. Prior treatment with docetaxel, cabazitaxel, or other taxane chemotherapy (prior docetaxel [up to 6 cycles] for hormone-sensitive prostate cancer is allowed if the last dose was at least 6 months prior to study treatment initiation)
2. Prior treatment with enzalutamide or similar therapy other than abiraterone
3. Active or history of autoimmune disease or immune deficiency
4. History of severe allergic reactions to antibody therapy
5. Concomitant use of a medication prohibited by the protocol (including certain transporter substrates as well as known strong CYP3A4 inducers and CYP3A4 inhibitors) within 4 weeks prior to and throughout study treatment

Exclusion Criteria for Participants receiving a docetaxel-containing treatment

1. Prior treatment with docetaxel, cabazitaxel, or other taxane chemotherapy
2. Active or history of autoimmune disease or immune deficiency
3. History of severe allergic reactions to antibody therapy
4. Concomitant use of a medication prohibited by the protocol (including certain transporter substrates as well as known strong CYP3A4 inducers and CYP3A4 inhibitors) within 4 weeks prior to and throughout study treatment

Exclusion Criteria for all other Participants

1. Prior treatment with docetaxel, cabazitaxel, topoisomerase 1 inhibitors, or other taxane chemotherapy
2. Active or history of autoimmune disease or immune deficiency
3. History of severe allergic reactions to antibody therapy
4. Concomitant use of a medication prohibited by the protocol (including certain transporter substrates as well as known strong CYP3A4 inducers and CYP3A4 inhibitors) within 4 weeks prior to and throughout study treatment