Randomized, double-blinded, phase II trial of a WT1 peptide vaccine as adjuvant therapy in patients with malignant pleural mesothelioma (MPM).

TPS139 Background: The transcription factor, WT1, is commonly over-expressed in MPM and immunohistochemical tests for WT1 are used diagnostically. Certain WT1 peptides are processed and presented to the immune system and are thus an attractive target for T cell based immunotherapy. Using computer prediction analysis we designed analog peptides derived from WT1 sequences by substituting amino acids at key HLA-A0201 binding positions. We tested the safety and immunogenicity of a WT1 vaccine comprised of four peptides in patients with thoracic neoplasms expressing WT1 (Krug et al, Cancer Immunol Immunother, 2010). Six out of nine patients tested demonstrated CD4 T-cell proliferation to WT1 specific peptides, and all five HLA-A0201 patients tested mounted a CD8 T-cell response. One patient remains without progression >30 months after the start of the study. The median survival (measured from the date of the first vaccinations) was 13 months. Based on this pilot trial, we proposed a randomized phase II trial i...