Vaccination with survivin and PSMA-derived peptides for controlling biochemical recurrence in prostate cancer: A pilot study

e16042 Background: A significant percentage of patients (pts) progress after first line treatment of prostate cancer (PCa). We present preliminary results of pilot study using a multiple peptide-based anti-tumor vaccine. Methods: A phase I-II trial of vaccination (vax) with HLA-A*0201-restricted peptides from PSMA and Survivin was carried out in 20 pts with b-failure after surgery or radiotherapy (mean pre-vax PSA: 1.83 ng/ml). Vax consisted of two peptides from PSMA (PSMA4–12 and PSMA711–719) and one from Survivin (SVV96–104/97M) given by 4 fortnightly (priming) and 4 monthly administrations (boosting). To selectively eliminate regulatory T cells (Treg) and possibly enhance immunization, peptides were preceded by low dose cyclophosphamide (CTX, 300 mg/mq, i.v.). Antigen (Ag) and tumor-specific T cell responses were extensively monitored in peripheral blood together with CD4+CD25+Foxp3+ Treg frequency. PSA trend was also registered. Results: Vax was well tolerated. Most pts (19/20) showed a significant in...