Immunization of Patients With Tumors Expressing NY-ESO-1 or LAGE Antigen With Complex of NY-ESO-1 Protein and Cholesterol-bearing Hydrophobized Pullulan (CHP)

NY-ESO-1 was isolated by serological analysis of recombinant cDNA expression libraries (SEREX), using tumor mRNA and autologous serum from an esophageal cancer patient. Reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that NY-ESO-1 displayed the typical expression pattern of CT antigens. NY-ESO-1 mRNA was expressed only in testis of normal tissues tested and in various types of cancer, including lung cancer, breast cancer, malignant melanoma and bladder cancer. LAGE-1 was identified by the representational difference analysis and revealed to display 84% amino acid homology with NY-ESO-1. In most cases, expression of LAGE-1 parallels the expression of NY-ESO-1. Since testis is an immune privileged organ where HLA molecules are not expressed, these antigens can be considered tumor-specific.

Because of frequent NY-ESO-1 mRNA expression and high immunogenicity in advanced cancer, NY-ESO-1 is an attractive target molecule for a cancer vaccine. Current therapies against advanced cancer have limited effectiveness. The idea of vaccination with NY-ESO-1 protein in cancer patients with tumors expressing NY-ESO-1 mRNA is based on two findings: 1) the number of CD8+ T cell epitopes identified in NY-ESO-1 molecule are limited to those binding to HLA-A0201, A31, Cw3 and Cw6. These HLA subtypes are carried by a minor Japanese population; 2) CD8+ T cell responses specific to NY-ESO-1 are polyclonal. Protein vaccination may induce immune response more effectively against tumors expressing NY-ESO-1 than peptide immunization.