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A randomized phase II study of flutamide with or without PSA-TRICOM in nonmetastatic castration-resistant prostate cancer (CRPC).
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2011
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UrologyOncologyGenitourinary CancerMedian SurvivalMedicineCancer ManagementMetronomic TherapyClinical TrialsPharmacotherapyImmunotherapeuticsCancer TreatmentMedian Gleason ScorePsa RisePharmacologyRadiation OncologyProstatic DiseaseCancer ResearchHealth Sciences
163 Background: PSA-TRICOM is a vector-based, therapeutic cancer vaccine regimen consisting of recombinant poxviruses containing the transgenes for prostate-specific antigen (PSA) and 3 T-cell co-stimulatory molecules (TRICOM). A previous randomized, placebo-controlled phase II study demonstrated an 8.5-month improvement in median survival (25.1 months for PSA-TRICOM group vs. 16.6 months for control group) in men with metastatic CRPC. Methods: This study is currently enrolling patients with non-metastatic CRPC on testosterone suppression therapy who have a rising PSA. Patients are stratified by PSA doubling time and randomized to androgen receptor antagonist alone (flutamide) or flutamide plus PSA-TRICOM. Flutamide is given at the standard dose of 400 mg TID while PSA-TRICOM is given by monthly subcutaneous injections. The primary endpoint of the study is time to treatment failure (TTF) which is defined as biochemical recurrence (PSA rise) or development of metastatic lesions on scans. Results: The first 26 patients enrolled are evaluated in this analysis. For flutamide alone (n = 13), the median age at enrollment was 64.7 years and median Gleason Score was 8. For flutamide + PSA-TRICOM (n = 13), the median age at enrollment was 67.1 years and median Gleason score was 8. Median time to progression is 223 days for Fluatmide + PSA- TRICOM (range 70-638) vs. 85 days for Flutamide alone (56-372). Progression for 11/12 flutamide alone patients and 9/10 fluatmide + PSA-TRICOM patients has been by PSA rise only. Conclusions: Preliminary evidence suggests improvement in time to treatment failure using combination of hormonal therapy with flutamide + PSA-TRICOM vaccine compared to fluatmide alone in patients with non-metastatic CRPC. This trial will continue to accrue a total of 62 patients and also will evaluate immunological responses. No significant financial relationships to disclose.