FOLLOW-UP EVALUATION OF PROSTATE-CANCER PATIENTS INFUSED WITH AUTOLOGOUS DENDRITIC CELLS PULSED WITH PSMA PEPTIDES

BACKGROUND. We recently conducted a phase I clinical trial administeri ng autologous dendritic cells pulsed with prostate-specific membrane a ntigen (PSMA) peptides to advanced prostate cancer patients. Participa nts were divided into 5 groups receiving 4 or 5 infusions of peptides alone (PSM-P1 or -P2; groups 1 and 2, respectively), autologous DC (gr oup 3), or DC pulsed with PSM-P1 or -P2 (groups 4 and 5, respectively) . Seven partial responders were observed. Follow-up evaluation of thes e responders is presented in this report. METHODS. Clinical monitoring for hematological studies and prostate markers was conducted up to 37 0 days from the start of the phase I study. Data collected include: ly mphocyte, hematocrit, alkaline phosphatase, prostate-specific antigen (PSA), free PSA, and PSMA levels. RESULTS. Groups 4 and 5 (patients in fused with DC pulsed with PSM-P1 or -P2) represented 5/7 responders. T he length of response was between 100 days (1 patient) to 200 days or above (6 patients). Four patients still remained responsive at the end of the period of observation. CONCLUSIONS. The responses observed in this phase I clinical trial are significant and of long duration. Most of the responders were in treatment groups infused with DC pulsed wit h PSM-P1 or -P2, suggesting the requirement of both components for eff ective immunotherapy. (C) 1997 Wiley-Liss, Inc.