Immunotherapy for cancer has had two main approaches that have lead to clinical applications. The first is stimulating immune responses to tumor cells with cytokines or cellular immunotherapy and the second is blocking tumor immune evasion and the associated inhibition of T-cell activation with antibodies to the CTLA-4 receptor, PD-1 receptor or PD-L1. We have taken a different approach and have developed therapeutic cancer vaccines that are a combination of tumor antigens (whole cells or proteins) with biological adjuvants (the cytokines IL-2 and GM-CSF). This study is a Phase 1a/1b clinical trial of a PSA/IL-2/GM-CSF vaccine in recurrent prostate cancer in hormone-naïve and hormone-independent patients. Major inclusion criteria include adenocarcinoma of the prostate, rising serum PSA and no measurable disease. Phase 1a examines the rate of dose limiting adverse events (DLAEs) in an initial course of 6 vaccinations (“induction vaccination”). The Phase 1b examines the rate of DLAEs with a continued course of an additional 6 vaccinations (“maintenance vaccine”). All patients will receive intradermal injections of the PSA/IL-2/GM-CSF vaccine at weeks 1, 2, 3, 7, 11, and 15. In an additional 28 patients the six maintenance vaccines will alternate IL-2 and the complete vaccine (PSA/IL-2/GM-CSF) at weeks 23, 27, 31, 35, 39 and 43. To date, twelve of twenty patients in the Phase 1a portion of the trial have received at least one vaccine injection and ten patients have received all 6 vaccines. Seven of the ten patients that have received 3 vaccines had increased responses to PSA in a lymphocyte blastogenesis assay and five of the nine patients had an increase in their response after 6 vaccines. None of the patients vaccinated in the Phase 1a portion have had a DLAE and enrollment continues in the Phase 1a.

Citation Format: Jonathan F. Head, Gregory A. Daniels, Michelle McKinney, Weg Ongkeko, Jessica Wang-Rodriguez, Kyoko Sakamoto, Robert L. Elliott. Phase 1 clinical trial of a therapeutic prostate cancer vaccine containing PSA/IL-2/GM-CSF in PSA defined biochemical recurrent prostate cancer patients. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A048.