Abstract
BACKGROUND: This phase II nonrandomized study evaluated the efficacy and safety of AZD4635 in combination with durvalumab (Arm A) or durvalumab plus cabazitaxel (Arm B) in patients with metastatic castration-resistant prostate cancer (mCRPC) previously treated with docetaxel and ≥1 novel hormonal agent. PATIENTS AND METHODS: The primary endpoint was radiographic progression-free survival (rPFS) per RECIST v1.1 (soft tissue) or the Prostate Cancer Clinical Trials Working Group 3 (bone). Secondary endpoints included safety, tolerability, overall survival, confirmed prostate-specific antigen (PSA(50)) response, pharmacokinetics, and objective response rate. Enrollment in Arm A was stopped following a sponsor decision unrelated to safety. The study was stopped based on the planned futility analysis due to low PSA(50) response in Arm B. RESULTS: In the final analysis (1 November 2021), 30 patients were treated (Arm A, n = 2; Arm B, n = 28). The median rPFS in Arm B was 5.8 months (95% confidence interval 4.2-not calculable). Median rPFS was 5.8 months versus 4.2 months for patients with high versus low blood-based adenosine signature. The most common treatment-related adverse events in Arm B were nausea (50.0%), diarrhea (46.4%), anemia and neutropenia (both 35.7%), asthenia (32.1%), and vomiting (28.6%). Overall, AZD4635 in combination with durvalumab or AZD4635 in combination with cabazitaxel and durvalumab showed limited efficacy in patients with mCRPC. CONCLUSIONS: Although the safety profile of both combinations was consistent with known safety data of the individual agents, the results of this trial do not support further development of the combinations.