Immunotherapy With Provenge (APC8015) For Androgen Independent Prostate Cancer: Final Survival Data From A Phase 3 Randomized Placebo-Controlled Trial

Paul F Schellhammer¹, Robert M Hershberg*^2
1Eastern Virginia Medical School, Norfolk, VA;²Dendreon Corporation, Seattle, WA

Introduction:
APC8015 is an investigational immunotherapy product composed of autologous antigen presenting cells (APCs) loaded with PA2024. PA2024 is a recombinant fusion protein comprised of prostatic acid phosphatase (PAP) and a targeting molecule (GM-CSF). A Phase 3 trial was conducted to test efficacy among patients with metastatic androgen independent disease.
Methods:
Patients were randomized (2:1) to receive activated dendritic cells APC8015 (n=82) or non-activated cells (n=45). The primary endpoint was time to objective disease progression. Monitoring was by serial radiologic imaging which was centrally reviewed. Patients were followed for survival for 36 months following randomization.
Results:
All 127 randomized patients are considered in this intent-to-treat (ITT) analysis. Baseline characteristics between arms were similar. The median survival was 25.9 months for patients randomized to APC8015 compared with 21.4 months for the placebo group (P = 0.01 (log-rank); hazard ratio (HR) = 1.7). The final 36-month survival rate of patients treated with APC8015 was 34% compared with 11% in the placebo group (P = 0.0046 (chi-squared)). Treatment was associated with few side effects and no patient withdrew from therapy due to side effects.
Conclusions:
An ITT analysis of survival demonstrated that APC8015 provided a survival advantage of 4.5 months and resulted in a significantly greater percentage of patients alive at 36 months (34% versus 11%). APC8015 was well tolerated. Urologists will need to be familiar with new biologicals entering the treatment arena.

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