IMMUNOGENICITY AND ANTITUMOR-ACTIVITY OF A LIPOSOMAL MUC1 PEPTIDE-BASED VACCINE

A human MUC1-transfected mouse mammary adenocarcinoma cell line (GZHI) was used to develop both subcutaneous and intravenous tumor models, A vaccine formulation comprised of a 24 mer (human MUC1) synthetic pept ide encapsulated with monophosphoryl lipid A adjuvant (MPLA) in multil amellar liposomes was tested for immunogenicity and anti-tumor activit y. A low dose of the human MUC1 peptide (5 mu g) administered in lipos omes provided excellent protection of mice in both tumor challenge mod els, The protective antitumor activity mediated by the liposome formul ation correlated with anti-MUC1-specific T-cell proliferation, gamma-i nterferon (IFN-gamma) production and IgG(2a) anti-MUC1 antibodies, sug gesting a type 1 (T-1) T-cell response. In contrast, lack of protectio n in mice immunized with negative control vaccines correlated with IgG (1) anti-MUC1 antibody formation, low or no anti-MUC1 IgG(2a), and low antigen-specific T-cell proliferation, consistent with a type 2 (T-2) T-cell response to the tumor. (C) 1998 Wiley-Liss, Inc.