Feasibility and Immune Response of WT1 Peptide Vaccination in Combination with OK-432 for Paediatric Solid Tumors

Background/aim Wilms' tumor 1 (WT1) peptide-based vaccination has been reported for its potential usefulness in targeting several cancers. The adjuvant drug OK-432 is known to have potent immunomodulation and therapeutic properties when applied in cancer treatment and may, thus, be important to trigger the appropriate immunological response in paediatric patients with a solid tumor that are vaccinated with a WT1 peptide. Patients and methods Paediatric patients with a solid tumor were vaccinated with a WT1 peptide and OK-432 once every 2 weeks, for a total of seven times. Results Of the 24 patients, 18 completed the scheduled vaccinations. Sixteen patients had local skin symptoms and/or fever. In 1 patient, anaphylactic symptoms emerged at the time of the final injection, but these quickly subsided after the treatment. WT1-specific immunological responses were observed in 4 patients (22.2%). WT1 and HLA class I expression were confirmed in 100% and 85% of primary tumors, respectively. Conclusion WT1 peptide vaccine therapy combined with OK-432 appears to be relatively safe for children. However further studies in a larger number of patients are necessary to confirm its safety and efficacy.