matrix cohorts, according to the protocol plan. We were able to administer the maximum permitted dose of 10 8 pfu without any serious adverse events by vaccination of the first of 18 patients. These initial 18 patients were followed throughout the one-year period after injection. An additional 14 patients were treated at the MTD dose level, as planned in the protocol and confirmed by a letter to the FDA. The purpose of the additional patients was to have sufficient numbers of patients in the groups to statistically evaluate the anti -PSA immune responses induced by the Ad/PSA vaccine. In summary, 32 patients were treated in the study followed through the one-year period. Two additional patients were enrolled in the study (total number of enrolled patients, 34) but never received the vaccine and were therefore not evaluable. One patient chose to have radiation therapy instead of participating in the trial and the second was diagnosed with a second malignancy (melanoma) shortly after his enrollment in the phase I study. 1.4.1 Phase I study results The median age of the patients was 70.2 years (range, 52 to 89). The vaccine was administered as an aqueous suspension or in a collagen (Gelfoam) matrix to 32 patients. Sixteen (16/32) or 50% of the patients exhibited grade 1 vaccine-related adverse events (AE), 1/32 (3.1%) that exhibited a grade 2 AE, and one patient exhibited a grade 3 AE which was a decrease in neutrophil count. There were no vaccine-related grades 4 or 5 AEs.