Vaccination of high-risk breast cancer patients with mucin-1 (MUC1) keyhole limpet hemocyanin conjugate plus QS-21

Our objective was to determine whether an immune response can be generated against MUC1 peptide and against tumor cell MUC1 after vaccination with MUC 1-keyhole limpet hemocyanin (KLH) conjugate plus QS-21 in breast cancer pat ients. Nine patients with a history of breast cancer but without evidence of disea se were treated with MUC1-KLH conjugate plus QS-21, containing 100 mu g of MUC1 and 100 mu g of QS-21, s.c. vaccinations were administered at weeks 1, 2, 3, 7, and 19, Peripheral blood was drawn at frequent intervals to asses s antibody titers, Skin tests were placed at weeks 1, 3, 9, and 21 to deter mine delayed type hypersensitivity reactions. Common toxicities included a local skin reaction at the site of the vaccine , usually of 4-5 days' duration, and mild flu-like symptoms usually of 1-2 days' duration. High IgM and IgG antibody titers against synthetic MUC1 wer e detected. IgG antibody titers remain elevated from a minimum of 106-137 w eeks after the first vaccination. Binding of IgM antibody to MCF-7 tumor ce lls was observed in seven patients, although there was minimal binding of I gG antibody. Two patients developed significant antibody titers post-highdo se chemotherapy and stem cell reinfusion. There was no evidence of T cell a ctivation. This MUC1-KLH conjugate plus QS-21 was immunogenic and well tolerated in br east cancer patients. Additional trials are ongoing to determine the optima l MUC1 peptide for use in larger clinical trials. Further investigation of vaccine therapy in high-risk breast cancer is warranted.