A phase I study of vaccination with NY‐ESO‐1f peptide mixed with Picibanil OK‐432 and Montanide ISA‐51 in patients with cancers expressing the NY‐ESO‐1 antigen

We conducted a phase I clinical trial of a cancer vaccine using a 20‐mer NY‐ESO‐1f peptide (NY‐ESO‐1 91–110) that includes multiple epitopes recognized by antibodies, and CD4 and CD8 T cells. Ten patients were immunized with 600 μg of NY‐ESO‐1f peptide mixed with 0.2 KE Picibanil OK‐432 and 1.25 ml Montanide ISA‐51. Primary end points of the study were safety and immune response. Subcutaneous injection of the NY‐ESO‐1f peptide vaccine was well tolerated. Vaccine‐related adverse events observed were fever (Grade 1), injection‐site reaction (Grade 1 or 2) and induration (Grade 2). Vaccination with the NY‐ESO‐1f peptide resulted in an increase or induction of NY‐ESO‐1 antibody responses in nine of ten patients. The sera reacted with recombinant NY‐ESO‐1 whole protein as well as the NY‐ESO‐1f peptide. An increase in CD4 and CD8 T cell responses was observed in nine of ten patients. Vaccine‐induced CD4 and CD8 T cells responded to NY‐ESO‐1 91–108 in all patients with various HLA types with a less frequent response to neighboring peptides. The findings indicate that the 20‐mer NY‐ESO‐1f peptide includes multiple epitopes recognized by CD4 and CD8 T cells with distinct specificity. Of ten patients, two with lung cancer and one with esophageal cancer showed stable disease. Our study shows that the NY‐ESO‐1f peptide vaccine was well tolerated and elicited humoral, CD4 and CD8 T cell responses in immunized patients.