Dexamethasone did not suppress immune boosting by personalized peptide vaccination for advanced prostate cancer patients

To evaluate the immunological responses of personalized peptide vaccination combined with low-dose glucocorticoids for advanced hormone refractory prostate cancer (HRPC) patients (pts).Eleven pts with advanced HRPC were treated with the vaccination and low-dose glucocorticoids; 6 pts with 10 mg/day of prednisolone (PDL) followed by 1 mg/day of dexamethasone at the time of progression, 1 pt with PDL, and 4 pts with dexamethasone. Peptide-specific cellular and humoral responses were employed to monitor pre- and post- (6th) vaccination samples.The vaccination combined with glucocorticoids was well tolerated with no severe adverse effects. Increments of IgG responses were observed in 1 of 4 or 8 of 10 pts tested who received PDL or dexamethasone, respectively, increment of cytotoxic T lymphocyte activity was observed in 2 of 4 or 5 of 7 pts tested, respectively. Vaccination with PDL or dexamethasone resulted in a decline of PSA (at least 50%) in 1 of 7 or 6 of 10 pts with significantly longer median TTP in the dexamethasone group, respectively.Vaccination combined with dexamethasone could be recommended for further clinical trials from both immunological and clinical points of view.