Main Points Sipuleucel-T appears promising as a vaccine that specifically targets prostate cancer (PCa) with minimal toxicities. The IMmunotherapy

for Prostate AdenoCarcinoma Treatment (IMPACT) double-blind randomized phase III study of 512 men with asymptomatic chemonaïve metastatic castration-resistant prostate cancer (CRPC) reported that the median survival was 25.8 months with sipuleucel-T compared with 21.7 months with placebo, and the 3-year survival also improved significantly Inhibitors,research,lifescience,medical (31.7% vs 23.0%; P = .032). The treatment effect remained consistent after adjustment for docetaxel use following investigational therapy. Formal approval by mid-2010 is expected, which would make this the first vaccine therapy US Food and Drug Administration (FDA)- approved for the treatment of cancer, after a plethora of previous phase III failures of cancer vaccines in Inhibitors,research,lifescience,medical other tumor types. The granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting vaccine GVAX (Cell Genesys, South San Francisco, CA) was a mixture of the PCa cell lines, PC-3 and LNCaP, transduced

with a replication-defective Inhibitors,research,lifescience,medical retrovirus containing cDNA for GM-CSF and then irradiated. Disappointingly, both the VITAL-1 trial that evaluated GVAX or docetaxel/prednisone for asymptomatic metastatic CRPC patients, and the VITAL-2 trial that evaluated GVAX plus docetaxel or docetaxel/prednisone in symptomatic metastatic CRPC patients, did not demonstrate improved outcomes

with GVAX, leading to early termination of both Inhibitors,research,lifescience,medical trials. Poxviruses represent a family of related double-stranded DNA viruses distinguished by their host specificity. A poxvirus (Prostvac)-expressing prostate-specific antigen and a triad of costimulatory molecules (TRICOM) have been studied in a double-blind placebo-controlled randomized phase II trial of 122 patients with chemonaïve Inhibitors,research,lifescience,medical minimally symptomatic metastatic CRPC. This trial demonstrated that Prostvac extended median survival (25.1 vs 16.6 mo; P = .0061) as well as 3-year survival (30% vs 17%). An emerging theme in phase III studies of vaccines (eg, sipuleucel-T and Prostvac) in medroxyprogesterone advanced PCa is one of prolonged survival, without a demonstrable signal of tumor shrinkage or delay in short-term disease progression. The development of vaccine approaches, either alone or in combination with other modalities, that may lead to objective measurable disease responses or delay in short-term disease progression would be a significant advance in the field and may lead to a more rapid and feasible pathway for their clinical development. Optimal patient selection is critical for selleck chemical trials evaluating vaccines and other immunotherapeutic agents for PCa. Preclinical data from animal models should inform the decision to select patients for clinical trials. Footnotes Relevant conflicts of interest: Dr.