Phase-I study of synthetic muc1 peptides in breast-cancer.

Exposed peptides in the repeat (VNTR) protein core of human mucin 1 (MUC1) could be a target for immunotherapy, as it is highly immunogenic in mice and a human cytotoxic T lymphocytes to MUC1 recognise the peptide. On this basis 13 patients were immunised with a MUC1 peptide - a 20 amino acids dimer conjugated with diphtheria toroid as carrier. In patients with established breast cancer increasing doses (0.15 mg, 0.25 mg, 0.5 mg, 1.0 mg) were used at 2 week intervals (3 injections). No toxicity was found, other than for DTH reaction to the diphtheria carrier; weak antibody and T cell proliferative responses were seen and weak DTH reaction in proportion of patients. The MUC1 peptide appears to be safe but in the form used was not highly immunogenic.