Melanoma patients immunized with melanoma cell vaccine induce antibody responses to recombinant MAGE-1 antigen

The MAGE-1 gene was recently characterized to encode an immunogenic tumor Ag on several types of human tumors, including melanoma. This Ag is expressed in a wide variety of human tumors and not in normal cells, except testicular tissue, as assessed through specific mRNA analysis. In this study we cloned the MAGE-1 gene exon 3 region from a colon carcinoma cell line and expressed it in Escherichia coli. The recombinant MAGE-1 protein was affinity purified. By using Western blot analysis, IgG and IgM anti-MAGE-1 Abs were detected in the sera of melanoma patients. Fifty-three patients immunized with a melanoma cell vaccine (MCV) were assessed for anti-MAGE-1 IgG responses by using a MAGE-1 Ag-specific ELISA. The MCV consisted of three melanoma cell lines that expressed MAGE-1. Comparisons of anti-MAGE-1 IgG response pre-MCV treatment with 12- to 16-wk post-MCV treatment were made. Fifty-seven percent of the patients immunized with the MCV showed significant enhancement of IgG response to recombinant MAGE-1 protein. Patients who responded had no particular HLA-A or -B allele expression pattern. Melanoma patients immunized with whole cell MCV containing MAGE-1 can enhance anti-MAGE-1 IgG Abs. Recombinant MAGE-1 protein can be used to assess patient response to MAGE-1 and will be investigated as a potential cancer vaccine against a wide variety of human tumors that express MAGE-1.