A randomized phase II study of pelareorep and docetaxel or docetaxel alone in men with metastatic castration resistant prostate cancer: CCTG study IND 209.

Background: Pelareorep is an oncolytic virus with activity in many cancers including prostate. It has in vitro synergism with microtubule-targeted agents. We undertook a clinical trial evaluating pelareorep in mCRPC patients receiving docetaxel.

Patients and Methods: In this randomized, open-label phase II study, patients received docetaxel 75mg/m2 on day 1 of a 21-day cycle and prednisone 5mg twice daily, in combination with pelareorep (arm A) or alone (arm B). The primary endpoint was 12 weeks lack of disease progression rate (LPD).

Results: Eighty-five pts were randomized. Median age was 69, ECOG performance status was 0/1/2 in 31%/66%/3% of patients. Bone/regional lymph node/liver metastases were present in 98%/24%/6%. The median prognostic score was slightly higher in Arm A (144 vs. 129 p= 0.005). Adverse events were as expected but more prevalent in arm A. The 12-week LPD rate was 61% and 52.4% in arms A/B (p=0.51). Median survival was 19.1 on Arm A and 21.1 months on Arm B (HR 1.83; 95% CI 0.96 to 3.52; p=0.06). No survival benefit of pelareorep was found.

Conclusion: Pelareorep with docetaxel was tolerable with comparable LPD in both arms but response and survival were inferior and so this combination does not merit further study.