Wilms' Tumor 1 Peptide Research Articles

Potential of dendritic cell immunotherapy for relapse after allogeneic hematopoietic stem cell transplantation, shown by WT1 peptide‐ and keyhole limpet hemocyanin‐pulsed, donor‐derived dendritic cell vaccine for acute myeloid leukemia

Induction of leukemia-specific immune responses is a promising treatment for acute myeloid leukemia. A 58-year-old woman received Wilms' tumor 1 (WT1) peptide- and keyhole limpet hemocyanin (KLH)-pulsed, donor-derived dendritic cell (DC) vaccination for AML relapse after allogeneic stem cell transplantation. The vaccination induced immune responses to the naive antigen KLH, whereas definitive immune responses to WT1 were not detected. Leukemia gradually progressed despite of vaccination. This study indicates that DC vaccination can induce an antigen-specific immune response in a patient after allogeneic stem cell transplantation, thus representing a viable strategy to induce antigen-specific immune responses in such patients.

WT1 (Wilms' Tumor 1) Peptide Immunotherapy for Renal Cell Carcinoma

Tumor-specific immunotherapy with a Wilms' tumor 1 (WT1) peptide has been on clinical trial for leukemia, myelodysplastic syndrome, breast and lung cancers and is producing promising results. In this study, we treated three patients with renal cell carcinoma with an anchor modified, HLA-A*2402 binding WT1 peptide which was emulsified in Freund's incomplete adjuvant. In two patients tumor growth was suppressed and clinical response was evaluated as stable disease by the RECIST criteria after 3 months of weekly immunizations. Notably, development of new metastases has stopped in these patients for a prolonged period. No deleterious side effects were observed. Peptide-specific T cells were expanded in PBMCs of the patients and a substantial fraction of them bore the surface phenotype consistent with a CD8+ cytotoxic effector population. Although established tumors did not regress further, considering the component of the vaccine, i.e. peptide alone, the stabilization effect suggested the potential of WT1 peptide to develop into a more effective vaccine. To our knowledge, this is the first report of WT1 immunotherapy for renal cell carcinoma. Hopefully, the results will stimulate more extensive clinical studies.

Immunotherapy for leukemia cells by using cytotoxic T lymphocyte specifically against WT1-derived peptide: an experimental study in vitro

To investigate the effect of targeting immunotherapy for leukemia cells by using cytotoxic T lymphocyte (CTL) specifically against WT (Wilm's tumor) 1-derived peptide. A 9-mer WT1 peptide (CMTWNQMNL) containing HLA-A*0201-binding anchor motifs was synthesized. Dendritic cells (DCs) generated from the peripheral blood mononuclear cells of an HLA-A*0201-positive healthy donor were cultured and divided into 2 groups: experimental group to be loaded with Wilms' tumor 1 (WT1) peptide so as to elicit CTL's specifically for WT1 peptide, restricted by HLA-A*0201, and control group. Six days later rhTNF-alpha was added for 3 days more to promote the maturation of DCs. Before loading of WT1 peptide and 2 days after the addition of rhTNF-alpha direct immunofluorescence labeling method was used with PE or FITC labeled mono-antibodies to detect the expression of the surface antigens: CD83, CD1alpha, CD80, CD86, CD14, and HLA-DR. DCs suspended and attached to wall were collected and then divided into 2 groups: pure T cell group (group D) to be cultured in culture medium without IL-2, and IL-2 + T cell group (Group C) to be cultured in 1640 culture medium with IL-2. Eight days later the T cells of Group C were co-cultured with the DCs of the experimental group (WTI peptide + DC + IL-2 + T cells, Group A) or the DCs of the control group (DC + IL-2 + T cells, Group B). Five days later the killing activity was detected. The CTLs of Groups A, B, and C at logarithmic growth phase were mixed with leukemic cells of the lines: NB4/WT1D, NB4WT1A, NB4 (all HLA-A*0201 +, WT1 +), U937 (HLA-A*0201 +, WTl -), and K562 (HLA-A*0201 -, WTI +), and mononuclear cells of the bone marrow of leukemic patients at different effector cell-target cell of 20:1 and 10:1. MTT method was used to examine the killing rate of CTL to the target cells. (1) The killing rates of Group A cells to NB4/WT1 D, NB4WTA, and NB4, leukemic cells were 60.4% +/- 3.1%, 56.4% +/- 5.7%, and 55.0% +/- 3.7%, all significantly higher than those of the Group B cells (10.9% +/- 1.6%, 11.1% +/- 2.7%, and 11.9% +/- 2.5%), and those of Group C cells (9.1% +/- 1.0%, 9.2% +/- 1.7%, and 9.4% +/- 1.8%) (all P < 0.01). There were no significant differences in the killing rates to U937 and K562 leukemic cells among the 3 groups. (2) When the effect-target ratio was 20: 2, the killing activity of the CTLs of Group A to the HLA-A*0201 +, WT1 + NB4/WT1 D, NB4/WT1A and NB4 leukemic cells was significantly higher than those to the HLA-A*0201 +, WT1 - U937 cells and the HLA-A*0201 -, WT1 + K562 cells (both P < 0.001), however, not significantly different from that to the U937 and K562 cells. (3) There were no significant differences in the killing activity of Group A cells to NB4/WT1D, NB4/WT1A, and NB4 cells (P = 0. 065, P = 0.621). (4) When the effect-target ratio was 10:2, the killing rates of Group A cells to the NB4/ WT1D, NB4/WT1A, and NB4 cells were 45.9% +/- 3.9%, 43.9% +/- 3.7%, and 44.1% +/- 3.2% respectively, all significantly lower than those when the effect-target ratio was 20:1 (all P < 0.01). CTLs specific for WT1 and restricted by HLA-A*0201 exert specific lysis upon leukemia cell lines and primary leukemia cells, but not upon normal hematopoietic cells, which provides a rationale for developing a strategy of WT1 peptide-based adoptive T-cell therapy and vaccination for human leukemia and solid tumors.

Detection of T-Cells Specific for Leukemia-Associated Antigens in Pediatric Patients with Acute Lymphoblastic Leukemia in First Complete Remission.

The ability of allogeneic hematopoietic stem cell transplantation to cure leukemia provides compelling evidence that the human immune system is able to mediate an effective anti-tumor effect and, as such, provides a rationale for the development of immune-mediated therapies for this disease. To design such therapies, it is necessary to identify both suitable target antigens and also the disease stages at which immune mechanisms are effective. One promising candidate antigen is the Wilms' tumor 1 (WT1) protein which is over-expressed, relative to normal hematopoietic progenitors, by most adult and pediatric leukemias. In this study, we investigated whether T-cells specific for a dominant WT1 epitope could be detected in pediatric patients with acute lymphoblastic leukemia (ALL) in complete remission (CR) following treatment with conventional chemotherapy alone. After informed consent, peripheral blood was obtained from 20 HLA-A*0201 positive children with ALL and from 3 HLA-A*0201 positive children with chemotherapy-treated, non-hematologic malignancies. All patients had completed therapy and were in CR. Blood was also obtained from 11 HLA-A*0201 positive healthy volunteers. Interferon-g (IFN-g) production by peripheral blood T-cells specific for the WT1-derived HLA-A*0201 binding peptide RMFPNAPYL was detected using the enzyme-linked immunospot (ELISPOT) assay. A mixture of HLA-A*0201 restricted immunodominant influenza, cytomegalovirus, and Epstein-Barr virus epitopes was used as a positive control. Absence of peptide was used as a negative control. IFN-g production in response to the WT1 peptide antigen was observed in 7/20 (35%) ALL patients, of which 4/7 had spots detected in wells containing 1 x 106 PBMC's and 3/7 had spots detected in wells containing 0.25 x 106 PBMC's. All samples secreted IFN-g in response to the positive control peptide mix. No IFN-g production was detected in the absence of peptide. All ALL patients in whom a WT1 response was detected were 2.5 – 5 years following therapy completion. Of the 13 ALL patients with no WT1 response, 6/13 were less than 2 years and 5/13 greater than 5.5 years following therapy completion. All other clinical and biologic features were evenly distributed between those with and without a WT1 response. No response to WT1 was observed in any of the three patients with non-hematologic malignancies, all of whom were 1.9–5.2 years following therapy completion, or in any of the healthy volunteers. T-cell responses to the WT1 leukemia-associated antigen can develop in pediatric patients with ALL. The generation of this specific T-cell population requires the presence of WT1 protein over-expressing leukemic cells, as indicated by the results from our control groups and in agreement with previous reports. This is the first study to report the development of T-cells specific for leukemia-associated antigens in pediatric patients with ALL treated with conventional chemotherapy alone. The findings suggest that tumor antigen specific T-cells may play a role in the maintenance of CR and that WT1 is an appropriate target for the development of immune-mediated therapies for pediatric ALL.