The role of sipuleucel-T in therapy for castration-resistant prostate cancer: a critical analysis of the literature

Context: Sipuleucel-T, an autologous antigen-presenting cell vaccine loaded with prostate acid phosphatase conjugated with granulocyte-macrophage colony-stimulating factor (GM-CSF), yielded a survival advantage in men with metastatic castration-resistant prostate cancer (mCRPC).

Objective: Critically analyze the role of sipuleucel-T in therapy for mCRPC.

Evidence acquisition: A systematic review of the literature was performed in June 2011 using Medline and an abstract search of major cancer conferences. The search strategy included the terms sipuleucel-T, APC-8015, castration-resistant, prostate cancer, and immunotherapy.

Evidence synthesis: The era of targeted immunotherapy was initiated with the regulatory approval in 2010 of sipuleucel-T for asymptomatic and minimally symptomatic mCRPC. The median survival was prolonged by 4.1 mo (25.8 vs 21.7 mo; hazard ratio: 0.78; 95% confidence interval, 0.61-0.98; p=0.03), coupled with an improvement in 3-yr survival (31.7% vs 23.0%). Outcomes were characterized by the lack of tumor regression or delay in progression. Further development is proceeding in earlier stages of prostate cancer and in the context of a host of emerging agents.

Conclusions: The addition of sipuleucel-T, an immunotherapeutic agent, to the armamentarium represents a paradigm shift in therapy for mCRPC. The rational combination and proper sequencing of sipuleucel-T with other newly approved agents (abiraterone acetate, cabazitaxel) and emerging agents (MDV3100, TAK-700, ipilimumab) will be important to evaluate.