Pilot study of WT1 peptide-pulsed dendritic cell vaccination with docetaxel in esophageal cancer

In the present study, the immune response to Wilms tumor gene 1 (WT1) peptide-pulsed dendritic cell (DC) vaccination combined with docetaxel (DCDOC) in advanced esophageal cancer patients who had already received first-line chemotherapy was investigated. Ten HLA-A*2402 patients were treated with docetaxel (50 mg/m²) on day 1 and WT1 peptide-pulsed DC vaccination (1×10⁷ cells) on days 15 and 22 (repeated every 4 weeks for 3 cycles). The delayed-type hypersensitivity skin test, HLA tetramer assay and interferon-γ enzyme-linked immunospot (ELISPOT) assay were used to evaluate the induction of a WT1-specific immune response. Median overall survival was 5 months (range, 1.1-11.6). The clinical effect of DCDOC therapy was not observed and only 1 patient could complete the protocol therapy. Disease progression was observed in 9 patients and 1 patient succumbed to fatality during the second cycle of therapy. As a pilot study, it was not possible to evaluate the safety of WT1 peptide-pulsed DCDOC therapy for esophageal squamous cell cancer. However, a WT1-specific response in 6 patients, as indicated by the ELISPOT or HLA/WT1-tetramer assay, was demonstrated. The results suggested that the positive immune response had significant relevance on the low percentage of CD11b⁺ and CD66b⁺ granulocytic myeloid-derived suppressor cells in CD15⁺ cells. Furthermore, DCDOC elicited a WT1-specific immune response regardless of the myelosuppression associated with docetaxel. The present findings support future studies and further work to assess DCDOC as an adjuvant therapy for esophageal cancer will be performed. The present clinical trial was registered in the University Hospital Medical Information Network (UMIN) Clinical Trials Registry on November 11th, 2011, no. UMIN000006704.