Prostvac-VF: a vector-based vaccine targeting PSA in prostate cancer

Prostvac is a prostate cancer vaccine regimen consisting of a recombinant vaccinia vector as a primary vaccination, followed by multiple booster vaccinations employing a recombinant fowlpox vector. Both vectors contain the transgenes for prostate-specific antigen (PSA) and multiple T-cell co-stimulatory molecules (TRICOM). The PSA-TRICOM vaccines infect antigen-presenting cells (APCs) and generate proteins that are expressed on the surface of the APCs in an immune context. The interaction of these APCs with T cells initiates a targeted immune response and T cell-mediated tumor cell destruction. Preliminary clinical trials have indicated negligible toxicity, and Phase 11 trials have suggested a survival benefit after treatment with Prostvac, especially in patients with indolent disease characteristics. Preclinical and clinical data indicate that radiation, hormonal therapy, and chemotherapy may be combined with Prostvac to enhance the vaccine's efficacy. Additional strategies are in development to further enhance the clinical benefits of Prostvac, and a Phase III trial is being planned in metastatic castration-resistant prostate cancer.