Personalized peptide vaccine in prostate cancer: capitalizing on existing immunity

As immunotherapy takes the center stage among emerging cancer strategies, recent data in prostate cancer was striking at first glance. Dr. Yoshimura and colleagues enrolled men with castration resistant prostate cancer (CRPC) from two institutions in Japan to either treatment with 1 mg dexamethasone alone or in combination with immunotherapy (1). The immunotherapy strategy in this trial was personalized to the existing anti-tumor humoral responses existing within each patient. Once existing IgG responses were detected and matched to at least one of 24 “warehouse peptides”, the appropriate peptides were administered subcutaneously every 2 weeks until progression, death, or intolerance. Patients could receive up to four peptides matching existing IgG findings in their blood. Progression was determined based on PSA parameters. Patients on the control arm were allowed to cross over.