Improved immune response and anti-tumor effect of WT1 peptide emulsion adjuvant vaccine for acute myeloid leukemia

Objective To evaluate the stability, safety and immune enhancement and anti-tumor effects of Wilms' tumor gene 1 (WT1) peptide combined with AddaVaxTM emulsion vaccine for acute myeloid leukemia. Methods The stability of WT1 peptide in the adjuvant vaccine was evaluated using MALDI-TOF-MS time-of-flight mass spectrometry. Female C57BL/6 mice were randomly divided into PBS group, WT1 peptide group, and WT1 peptide+AddaVaxTM emulsion adjuvant vaccine group. The immunization was performed at a dose of 50 μg/mouse for antigen and 50 μg/mouse for adjuvant, with intramuscular injection on days 0, 14, and 28. HE staining was used to assess the toxicity of intramuscular vaccination on mouse organ tissues. Cytokine levels were detected by ELISA, and the number of IFN-γ-secreting splenocytes was measured by ELISpot. Flow cytometry was employed to detect the maturation of bone marrow-derived dendritic cells (BMDCs) promoted by the vaccine in vitro and the promotion for lymphocyte activation, and H-2Db WT1 tetramer was utilized to detect the proportion of specific CD8+ T cells. After establishing a mouse leukemia tumor model using the C1498-mWT1 stable cell line, the anti-tumor effects of the vaccine for prevention and treatment were evaluated. Results The WT1 peptide stably existed in the vaccine without causing significant organ tissue changes in mice after intramuscular injection. Compared to the mice immunized with WT1 aqueous solution, the mice after intramuscular injection of the WT1 peptide emulsion adjuvant vaccine showed stronger immune responses of Th1 cells, including IFN-γ and TNF-α, as well as Th17 cells of IL-17A (P