Wilms' tumor 1 peptide-loaded dendritic cell vaccination in patients with relapsed or refractory acute leukemia.

ABSTRACT

INTRODUCTION: The prognosis of patients with relapsed or refractory acute leukemia is poor. In the present pilot study, we treated relapsed or refractory acute leukemia patients with Wilms' tumor 1 (WT1) peptide-loaded dendritic cells (DCs) and examined safety, clinical and immunological responses. METHODS: Eleven eligible patients were enrolled. DCs were administered every 2-3 weeks with OK-432 adjuvant. RESULTS: The treatment was well tolerated. The reduction of leukemia cells or the expression of WT1 mRNA was observed in four patients which was maintained for a significant period of time. All the responding patients manifested immune responses against WT1 which might be related to clinical outcome. Decreases in the absolute number of regulatory T cells were observed following vaccination, indicating that DC vaccinations may contribute to the reversal of immunosuppression. CONCLUSION: These results indicate that DC-based immunotherapy is safe and feasible for patients with acute leukemia.