Every week, the patients received alternately a vaccine containing 3 mg of WT1HLA-A*24:02-restricted (HLA class I) peptide and a cocktail vaccine of the HLA class I peptide and one of 0.75, 1.5 or 3 mg of the WT1 HLA class II peptide.
The expanded CTLs were cytotoxic toward WT1<sub>235-243</sub>-peptide-loaded HLA-A*24:02-positive cell lines and exerted a potent antileukemic effect in vivo.
Immune responses (IRs) were evaluated after the 6th and 12th vaccinations by CD4<sup>+</sup> T-cell proliferation, CD8<sup>+</sup> T-cell interferon-γ secretion (enzyme-linked immunospot), or the CD8-relevant WT1 peptide major histocompatibility complex tetramer assay (HLA-A*02 patients only).
In the present study, we developed CAR-T cells consisting of a single chain variable fragment (scFv) specific to the WT1<sub>235-243</sub>/HLA-A*2402 complex.
T cells modified to express WT1-28z specifically targeted and lysed HLA-A*02:01+ WT1+ tumors and enhanced survival of mice engrafted with HLA-A*02:01+, WT1+ leukemia or ovarian tumors.
Immunodominant WT1 epitopes, the native HLA-A2/WT1<sub>126-134</sub> (<b>R</b>MFPNAPYL) (HLA-A2/RMFPNAPYL epitope (WT1A)) and its modified variant <b>Y</b>MFPNAPYL (HLA-A2/YMFPNAPYL epitope (WT1B)), can induce WT1-specific CD8<sup>+</sup> T cells, although WT1B is more stably bound to HLA-A*02:01.
RMFPNAPYL (RMF), a Wilms' tumor gene 1 (WT1)-derived CD8 T-cell epitope presented by HLA-A*02:01, is a validated target for T-cell-based immunotherapy.
In fact, presentation of HLA-A*2402-restricted antigenic peptide of WT1 (CMTWNQMNL) increased in GEM-treated MIAPaCa2 cells relative to untreated cells.
The frequencies of PB WT1 peptide-specific and HLA-A*2402-restricted CD8+ cells (p < 0.005) and WT1 peptide-stimulated interferon-gamma-producing MNCs (p < 0.02) were significantly higher in 5 PNH patients than 8 healthy volunteers (HV).
A CD8(+) CTL clone, designated TAK-1, which lysed autologous cells loaded with a WT1-derived 9-mer peptide consisting of the HLA-A24 (HLA-A*2402)-binding motifs was established by stimulating CD8(+) T lymphocytes from a healthy individual repeatedly with WT1 peptide-pulsed autologous dendritic cells.