Higher-dose and less frequent dendritic cell infusions with PSMA peptides in hormone-refractory metastatic prostate cancer patients

BACKGROUND. Infusion of dendritic cells (DCs) pulsed with PSMA peptides was considered possible in hormone-refractory metastatic prostate cancer patie nts both with or without prior treatment with a greater number of DCs and f or lesser infusions than previously administered. METHODS. DCs + PSMA peptides in patients undergoing leukapheresis were admi nistered monthly 1-4 times, at rates greater than 20 million DCs in 17 pati ents not previously treated, and in 11 patients previously treated. RESULTS. Three partial responders and one complete responder were noted in the 17 previously untreated persons. DCs + PSMA peptides averaged 28.5 mill ion cells (range in millions, 21.0-42.3). All responders received 3 or 4 in fusions of greater than 22 million cells (3-4 times). In the previously tre ated group of 11 patients, DCs infused averaged 29.3 million cells (range i n millions, 20-40.5). One new responder (bone scan) was noted. Two prior re sponders continued. Observation times were similar. Toxicity was minimal. CONCLUSIONS. These results suggest that DCs + PSMA peptide infusions can be given with greater numbers of DCs with a lesser number of infusions (1-4 m onthly) with no loss of response rates compared to those noted previously, and without increased side effects. In previously treated patients (both re lapsing and nonrelapsing), adverse effects were not noted, and new response s can be anticipated to be without harmful side effects. However, the follo w-up time, and number of patients in this group, were small. Prostate 43:59 -62, 2000. (C) 2000 Wiley-Liss, Inc.