Development of PROSTVAC immunotherapy in prostate cancer

PROSTVAC immunotherapy is a heterologous prime-boost regimen of two different recombinant pox-virus vectors; vaccinia as the primary immunotherapy, followed by boosters employing fowlpox, to provoke immune responses against prostate-specific antigen. Both vectors contain transgenes for prostate-specific antigen and a triad of T-cell costimulatory molecules (TRICOM). In a placebo-controlled Phase II trial of men with minimally symptomatic, chemotherapy-naive metastatic castration-resistant prostate cancer, PROSTVAC was well tolerated and associated with a 44% reduction in death. With a novel mechanism of action, and excellent tolerability, PROSTVAC has the potential to dramatically alter the treatment landscape of prostate cancer, not only as a monotherapy, but also in combination with other novel agents, such as immune check point inhibitors and novel androgen receptor blockers. A Phase III trial recently completed accrual.