Identification of mouse helper epitopes for WT1-specific CD4+ T cells

Helper T lymphocytes (HTLs) play a central role in cancer immunity because they can not only help the induction and proliferation of cytotoxic T lymphocytes (CTLs) but also their differentiation into cytotoxic CD4⁺ T cells and directly kill the target cells.This study describes the identification of three novel mouse Th epitope peptides, WT1_35-52, WT1_86-102 and WT1_294-312, derived from WT1 protein, which is the most potent tumor-associated antigen. Compared to immunization with WT1 CTL peptide alone, immunization with the addition of these WT1-specific Th peptides strongly induced WT1-specific CTLs, continued to maintain them, and efficiently rejected the challenge of WT1-expressing tumor cells. Importantly, the majority of WT1-specific CTLs induced by the co-immunization with WT1 CTL and the WT1-specific Th peptides were CD44⁺CD62L^- effector memory CD8⁺ T cells, which played a central role in tumor rejection. Establishment of mouse models suitable for the analysis of the detailed mechanism of these functions of HTLs is very important. These results clearly showed that WT1-specific HTLs perform an essential function in WT1-specific tumor immunity. Therefore, the WT1-specific Th peptides identified here should make a major contribution to elucidation of the mutual roles of WT1-specific CTLs and HTLs in cancer immunity in in vivo mouse models.

Wilms tumor gent 1 (WT1)-specific adoptive immunotherapy in hematologic diseases

As an attractive tumor-associated antigen (TAA), Wilms tumor gene 1 (WT1) is usually overexpressed in malignant hematological diseases. In recent years, WT1-specific adoptive immunotherapy has been the "hot spot" for tumor treatment. The main immunotherapeutic techniques associated with WT1 include WT1-specific cytotoxic T lymphocytes (CTLs), vaccine, and T cell receptor (TCR) gene therapy. WT1-based adoptive immunotherapy exhibited promising anti-tumorous effect with tolerable safety. There are still many limitations needed to be improved including the weak immunogenetics of WT1, immune tolerance, and short persistence of the immune response. In this review, we summarized the progress of productive technologies and the clinical or preclinical investigations of WT1-specific immunotherapy in hematological diseases.

Enhanced immune reaction resulting from co-vaccination of WT1 helper peptide assessed on PET-CT

It has become evident that positron emission tomography/computed tomography (PET-CT) using 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) (FDG PET-CT) can detect anti-tumor immune response induced by various immunotherapies. To evaluate whether FDG PET-CT could detect anti-cancer immune response caused by cancer vaccine therapy, we performed a retrospective analysis of FDG PET-CT imaging of patients who were treated with Wilms Tumor 1 (WT1) vaccine therapy in Osaka University during July 2008 and June 2018. Increased FDG uptakes were detected in WT1-vaccinated skin and their draining lymph nodes during the repeated vaccination. While the FDG uptakes seemed to decrease with time after the cessation of WT1 peptide vaccinations, persistence of FDG uptakes for years in WT1-vaccinated skin were also observed in 2 cases who showed good clinical course. Moreover, the FDG uptakes of patients treated with the combination vaccine of WT1 specific cytotoxic T cell (CTL) and helper peptides were significantly stronger than of those treated with the WT1 CTL peptide alone. Since it is evident that the combination vaccine can induce a more robust anti-tumor immunity than can CTL peptide vaccine alone, the FDG uptakes in WT1-vaccinated skin might reflect the degree of immune response. These results suggest that PET-CT might be a good tool for prediction of anti-tumor immune response induced by WT1 vaccine therapy. Larger scale prospective studies therefore seem to be warranted.

Identification of two distinct populations of WT1-specific cytotoxic T lymphocytes in co-vaccination of WT1 killer and helper peptides

Simultaneous induction of tumor antigen-specific cytotoxic T lymphocytes (CTLs) and helper T lymphocytes (HTLs) is required for an optimal anti-tumor immune response. WT1₃₃₂, a 16-mer WT1-derived helper peptide, induce HTLs in an HLA class II-restricted manner and enhance the induction of WT1-specific CTLs in vitro. However, in vivo immune reaction to WT1₃₃₂ vaccination in tumor-bearing patients remained unclear. Here, a striking difference in WT1-specific T cell responses was shown between WT1 CTL + WT1 helper peptide and WT1 CTL peptide vaccines in patients with recurrent glioma. WT1-specific CTLs were more strongly induced in the patients who were immunized with WT1 CTL + WT1 helper peptide vaccine, compared to those who were immunized with WT1 CTL vaccine alone. Importantly, a clear correlation was demonstrated between WT1-specific CTL and WT1₃₃₂-specific HTL responses. Interestingly, two novel distinct populations of WT1-tetramer^low WT1-TCR^low CD5^low and WT1-tetramer^high WT1-TCR^high CD5^high CTLs were dominantly detected in WT1 CTL + WT1 helper peptide vaccine. Although natural WT1 peptide-reactive CTLs in the latter population were evidently less than those in the former population, the latter population showed natural WT1 peptide-specific proliferation capacity comparable to the former population, suggesting that the latter population highly expressing CD5, a marker of resistance to activation-induced cell death, should strongly expand and persist for a long time in patients. These results demonstrated the advantage of WT1 helper peptide vaccine for the enhancement of WT1-specific CTL induction by WT1 CTL peptide vaccine.

The Antitumor Activity of TCR-Mimic Antibody-Drug Conjugates (TCRm-ADCs) Targeting the Intracellular Wilms Tumor 1 (WT1) Oncoprotein

Wilms tumor 1 (WT1) oncoprotein is an intracellular oncogenic transcription factor which is barely expressed in normal adult tissues but over expressed in a variety of leukemias and solid cancers. WT1-derived HLA-A*02:01 T cell epitope, RMFPNAPYL (RMF), is a validated target for T cell-based immunotherapy. We generated two T cell receptor mimic antibody-drug conjugates (TCRm-ADCs), ESK-MMAE, and Q2L-MMAE, against WT1 RMF/HLA-A*02:01 complex with distinct affinities, which mediate specific antitumor activity. Although ESK-MMAE showed higher tumor growth inhibition ratio in vivo, the efficacy of them was not so promising, which might be due to low expression of peptide/HLA targets. Therefore, we explored a bispecific TCRm-ADC that exerted more potent tumor cytotoxicity compared with TCRm-ADCs. Hence, our findings validate the feasibility of the presenting intracellular peptides as the targets of ADCs, which broadens the antigen selection range of antibody-based drugs and provides new strategies for precision medicine in tumor therapy.

Phase I/II clinical trial of a Wilms' tumor 1-targeted dendritic cell vaccination-based immunotherapy in patients with advanced cancer

Dendritic cell (DC)-based immunotherapies have been created for a broad expanse of cancers, and DC vaccines prepared with Wilms' tumor protein 1 (WT1) peptides have shown great therapeutic efficacy in these diseases. In this paper, we report the results of a phase I/II study of a DC-based vaccination for advanced breast, ovarian, and gastric cancers, and we offer evidence that patients can be effectively vaccinated with autologous DCs pulsed with WT1 peptide. There were ten patients who took part in this clinical study; they were treated biweekly with a WT1 peptide-pulsed DC vaccination, with toxicity and clinical and immunological responses as the principal endpoints. All of the adverse events to DC vaccinations were tolerable under an adjuvant setting. The clinical response was stable disease in seven patients. Karnofsky Performance Scale scores were enhanced, and computed tomography scans revealed tumor shrinkage in three of seven patients. Human leukocyte antigen (HLA)/WT1-tetramer and cytoplasmic IFN-γ assays were used to examine the induction of a WT-1-specific immune response. The immunological responses to DC vaccination were significantly correlated with fewer myeloid-derived suppressor cells (P = 0.045) in the pretreated peripheral blood. These outcomes offered initial clinical evidence that the WT1 peptide-pulsed DC vaccination is a potential treatment for advanced cancer.

Generation of TCR-Expressing Innate Lymphoid-like Helper Cells that Induce Cytotoxic T Cell-Mediated Anti-leukemic Cell Response

CD4⁺ T helper (Th) cell activation is essential for inducing cytotoxic T lymphocyte (CTL) responses against malignancy. We reprogrammed a Th clone specific for chronic myelogenous leukemia (CML)-derived b3a2 peptide to pluripotency and re-differentiated the cells into original TCR-expressing T-lineage cells (iPS-T cells) with gene expression patterns resembling those of group 1 innate lymphoid cells. CD4 gene transduction into iPS-T cells enhanced b3a2 peptide-specific responses via b3a2 peptide-specific TCR. iPS-T cells upregulated CD40 ligand (CD40L) expression in response to interleukin-2 and interleukin-15. In the presence of Wilms tumor 1 (WT1) peptide, antigen-specific dendritic cells (DCs) conditioned by CD4-modified CD40L^high iPS-T cells stimulated WT1-specific CTL priming, which eliminated WT1 peptide-expressing CML cells in vitro and in vivo. Thus, CD4 modification of CD40L^high iPS-T cells generates innate lymphoid helper-like cells inducing bcr-abl-specific TCR signaling that mediates effectiveanti-leukemic CTL responses via DC maturation, showing potential for adjuvant immunotherapy against leukemia.

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iPSC-derived T cells have molecular similarity to group 1 innate lymphoid cells

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iPSC-derived CD40L^high T cell-adjuvants induce leukemia-specific CTLs via DCs

Phase 2 trial of a multivalent WT1 peptide vaccine (galinpepimut-S) in acute myeloid leukemia

A National Cancer Institute consensus study on prioritization of cancer antigens ranked the Wilms tumor 1 (WT1) protein as the top immunotherapy target in cancer. We previously reported a pilot study of a multivalent WT1 peptide vaccine (galinpepimut-S) in acute myeloid leukemia (AML) patients. We have now conducted a phase 2 study investigating this vaccine in adults with AML in first complete remission (CR1). Patients received 6 vaccinations administered over 10 weeks with the potential to receive 6 additional monthly doses if they remained in CR1. Immune responses (IRs) were evaluated after the 6th and 12th vaccinations by CD4+ T-cell proliferation, CD8+ T-cell interferon-γ secretion (enzyme-linked immunospot), or the CD8-relevant WT1 peptide major histocompatibility complex tetramer assay (HLA-A*02 patients only). Twenty-two patients (7 males; median age, 64 years) were treated. Fourteen patients (64%) completed ≥6 vaccinations, and 9 (41%) received all 12 vaccine doses. Fifteen patients (68%) relapsed, and 10 (46%) died. The vaccine was well tolerated, with the most common toxicities being grade 1/2 injection site reactions (46%), fatigue (32%), and skin induration (32%). Median disease-free survival from CR1 was 16.9 months, whereas the overall survival from diagnosis has not yet been reached but is estimated to be ≥67.6 months. Nine of 14 tested patients (64%) had an IR in ≥1 assay (CD4 or CD8). These results indicated that the WT1 vaccine was well tolerated, stimulated a specific IR, and was associated with survival in excess of 5 years in this cohort of patients. This trial was registered at www.clinicaltrials.gov as #NCT01266083.

Development of oral cancer vaccine using recombinant Bifidobacterium displaying Wilms' tumor 1 protein

Several types of vaccine-delivering tumor-associated antigens (TAAs) have been developed in basic and clinical research. Wilms' tumor 1 (WT1), identified as a gene responsible for pediatric renal neoplasm, is one of the most promising TAA for cancer immunotherapy. Peptide and dendritic cell-based WT1 cancer vaccines showed some therapeutic efficacy in clinical and pre-clinical studies but as yet no oral WT1 vaccine can be administrated in a simple and easy way. In the present study, we constructed a novel oral cancer vaccine using a recombinant Bifidobacterium longum displaying WT1 protein. B. longum 420 was orally administered into mice inoculated with WT1-expressing tumor cells for 4 weeks to examine anti-tumor effects. To analyze the WT1-specific cellular immune responses to oral B. longum 420, mice splenocytes were isolated and cytokine production and cytotoxic activities were determined. Oral administrations of B. longum 420 significantly inhibited WT1-expressing tumor growth and prolonged survival in mice. Immunohistochemical study and immunological assays revealed that B. longum 420 substantially induced tumor infiltration of CD4+T and CD8+T cells, systemic WT1-specific cytokine production, and cytotoxic activity mediated by WT1-epitope specific cytotoxic T lymphocytes, with no apparent adverse effects. Our novel oral cancer vaccine safely induced WT1-specific cellular immunity via activation of the gut mucosal immune system and achieved therapeutic efficacy with several practical advantages over existing non-oral vaccines.

Targeting of the WT191-138 fragment to human dendritic cells improves leukemia-specific T-cell responses providing an alternative approach to WT1-based vaccination

Due to its immunogenicity and overexpression concomitant with leukemia progression, Wilms tumor protein 1 (WT1) is of particular interest for immunotherapy of AML relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT). So far, WT1-specific T-cell responses have mainly been induced by vaccination with peptides presented by certain HLA alleles. However, this approach is still not widely applicable in clinical practice due to common limitations of HLA restriction. Dendritic cell (DC) vaccines electroporated with mRNA encoding full-length protein have also been tested for generating WT1-derived peptides for presentation to T-cells. Alternatively, an efficient and broad WT1 peptide presentation could be elicited by triggering receptor-mediated protein endocytosis of DCs. Therefore, we developed antibody fusion proteins consisting of an antibody specific for the DEC205 endocytic receptor on human DCs and various fragments of WT1 as DC-targeting recombinant WT1 vaccines (anti-hDEC205-WT1). Of all anti-hDEC205-WT1 fusion proteins designed for overcoming insufficient expression, anti-hDEC205-WT110-35, anti-hDEC205-WT191-138, anti-hDEC205-WT1223-273, and anti-hDEC205-WT1324-371 were identified in good yields. The anti-hDEC205-WT191-138 was capable of directly inducing ex vivo T-cell responses by co-incubation of the fusion protein-loaded monocyte-derived mature DCs and autologous T-cells of either healthy or HSCT individuals. Furthermore, the DC-targeted WT191-138-induced specific T-cells showed a strong cytotoxic activity by lysing WT1-overexpressing THP-1 leukemia cells in vitro while sparing WT1-negative hematopoietic cells. In conclusion, our approach identifies four WT1 peptide-antibody fusion proteins with sufficient production and introduces an alternative vaccine that could be easily translated into clinical practice to improve WT1-directed antileukemia immune responses after allo-HSCT.

[WT1 peptide cancer vaccine]

Wilms'tumor gene 1(WT1) is a leukemia cell-specific marker, and WT1 protein is pan- tumor-associated antigen (TAA) that was ranked as a top among 75 TAAs. WT1 peptide vaccine has been performing for over 800 patients with 58 kinds of malignancies including leukemia and various types of solid tumors. Clinical results are promising, and adverse effects are limited to skin eruption on the vaccine injection sites. Two types of WT1 peptide vaccines are under clinical studies by pharmaceutical companies for the development of medicine.

[WT1 Class I Peptide/WT1 Class II Peptide Pulsed Dendritic Cell Therapy Efficacy in 60 Patients with a Wide Range of Advanced Cancers]

We assessed the efficacy of WT1 class I peptide and WT1 class II peptide pulsed dendritic cell(DC)therapy for a wide range of advanced cancers. This retrospective study included 60 advanced cancer patients who were vaccinated 5times or more in this clinic between September 2013 and December 2015. The clinical response was examined. This treatment was approved by the ethics panel at this institution. Sixty patients were injected an average of 6.15times with dendritic cells(DCs) (2.6×10 / 7 cells/injection). Overall, 55of 60(92%)patients achieved a clinical benefit per the RECIST v1.1 criteria. The median survival time(MST)from diagnosis was 26.9 months, and the MST from the first admission at this institution was 12.2 months. Complete response(CR)was achieved in 5patients(9.1%), partial response(PR)in 12(22%), and stable disease(SD) in 21(38%), with confirmed progressive disease(PD)in 17(31%). In 11 cases of pancreatic cancer, the response(RR)and disease control rates(DCR)were 27%and 55%,respectively. In 8 cases of colorectal cancer, the rates were 25% and 75%; in 7 cases of lung cancer, the rates were 29% and 43%; in 7 cases of gastric cancer, the rates were 71% and 86%; in 22 other types, the rates were 23% and 74%. These results demonstrated the potential clinical efficacy of DC-based immunotherapy.

Immunotherapy in Acute Leukemias: Implications and Perspectives Using Wt1 Antigen

The WT1 gene encodes a transcription factor involved in regulation of many cellular processes, including proliferation, differentiation, mRNA processing and apoptosis, besides acting as a transcription repressor of growth factors and their receptors' genes. This gene is expressed at high levels in several types of cancers, including acute leukemias. In this regard, many studies have identified WT1 protein as a tumor antigen, considered a target molecule for clinical application in human acute leukemias. Immunotherapy using WT1 antigen has been effective in stimulating immune responses against leukemic cells. Regarding adoptive immunotherapy, the use of dendritic cells (DCs) for the WT1-specific cytotoxic T cells generation proved to be efficient in the development and maintenance of immunologic cells. Therefore, these therapeutic methods, that provided enthusiasm for moving ahead, highlight several opportunities and challenges to be used in clinical practice for managing acute leukemias.

Dendritic cell-based cancer immunotherapy for colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers and a leading cause of cancer-related mortality worldwide. Although systemic therapy is the standard care for patients with recurrent or metastatic CRC, the prognosis is extremely poor. The optimal sequence of therapy remains unknown. Therefore, alternative strategies, such as immunotherapy, are needed for patients with advanced CRC. This review summarizes evidence from dendritic cell-based cancer immunotherapy strategies that are currently in clinical trials. In addition, we discuss the possibility of antitumor immune responses through immunoinhibitory PD-1/PD-L1 pathway blockade in CRC patients.

Prognostic significance of plasma interleukin-6/-8 in pancreatic cancer patients receiving chemoimmunotherapy

AIM: To investigate the association of plasma levels of interleukin (IL)-6 and -8 with Wilms’ tumor 1 (WT1)-specific immune responses and clinical outcomes in patients with pancreatic ductal adenocarcinoma (PDA) treated with dendritic cells (DCs) pulsed with three types of major histocompatibility complex class I and II-restricted WT1 peptides combined with chemotherapy.

METHODS: During the entire treatment period, plasma levels of IL-6 and -8 were analyzed by ELISA. The induction of WT1-specific immune responses was assessed using the WT1 peptide-specific delayed-type hypersensitivity (DTH) test.

RESULTS: Three of 7 patients displayed strong WT1-DTH reactions throughout long-term vaccination with significantly decreased levels of IL-6/-8 after vaccinations compared with the levels prior to treatment. Moreover, overall survival (OS) was significantly longer in PDA patients with low plasma IL-6 levels (< 2 pg/mL) after 5 vaccinations than in patients with high plasma IL-6 levels (≥ 2 pg/mL) (P = 0.025). After disease progression, WT1-DTH reactions decreased severely and were ultimately negative at the terminal stage of cancer. The decreased levels of IL-6/-8 observed throughout long-term vaccination were associated with WT1-specific DTH reactions and long-term OS.

CONCLUSION: Prolonged low levels of plasma IL-6/-8 in PDA patients may be a prognostic marker for the clinical outcomes of chemoimmunotherapy.

Engineering monocyte-derived dendritic cells to secrete interferon-α enhances their ability to promote adaptive and innate anti-tumor immune effector functions

Dendritic cell (DC) vaccination has demonstrated potential in clinical trials as a new effective cancer treatment, but objective and durable clinical responses are confined to a minority of patients. Interferon (IFN)-α, a type-I IFN, can bolster anti-tumor immunity by restoring or increasing the function of DCs, T cells and natural killer (NK) cells. Moreover, type-I IFN signaling on DCs was found to be essential in mice for tumor rejection by the innate and adaptive immune system. Targeted delivery of IFN-α by DCs to immune cells could boost the generation of anti-tumor immunity, while avoiding the side effects frequently associated with systemic administration. Naturally circulating plasmacytoid DCs, major producers of type-I IFN, were already shown capable of inducing tumor antigen-specific T cell responses in cancer patients without severe toxicity, but their limited number complicates their use in cancer vaccination. In the present work, we hypothesized that engineering easily generated human monocyte-derived mature DCs to secrete IFN-α using mRNA electroporation enhances their ability to promote adaptive and innate anti-tumor immunity. Our results show that IFN-α mRNA electroporation of DCs significantly increases the stimulation of tumor antigen-specific cytotoxic T cell as well as anti-tumor NK cell effector functions in vitro through high levels of IFN-α secretion. Altogether, our findings mark IFN-α mRNA-electroporated DCs as potent inducers of both adaptive and innate anti-tumor immunity and pave the way for clinical trial evaluation in cancer patients.

Two distinct effector memory cell populations of WT1 (Wilms' tumor gene 1)-specific cytotoxic T lymphocytes in acute myeloid leukemia patients

Wilms' tumor gene 1 (WT1) protein is a promising tumor-associated antigen for cancer immunotherapy. We have been performing WT1 peptide vaccination with good clinical responses in over 750 patients with leukemia or solid cancers. In this study, we generated single-cell gene-expression profiles of the effector memory (EM) subset of WT1-specific cytotoxic T lymphocytes (CTLs) in peripheral blood of nine acute myeloid leukemia patients treated with WT1 peptide vaccine, in order to discriminate responders (WT1 mRNA levels in peripheral blood decreased to undetectable levels, decreased but stayed at abnormal levels, were stable at undetectable levels, or remained unchanged from the initial abnormal levels more than 6 months after WT1 vaccination) from non-responders (leukemic blast cells and/or WT1 mRNA levels increased relative to the initial state within 6 months of WT1 vaccination) prior to WT1 vaccination. Cluster and principal component analyses performed using 83 genes did not discriminate between responders and non-responders prior to WT1 vaccination. However, these analyses revealed that EM subset of WT1-specific CTLs could be divided into two groups: the "activated" and "quiescent" states; in responders, EM subset of the CTLs shifted to the "quiescent" state, whereas in non-responders, those shifted to the "activated" state following WT1 vaccination. These results demonstrate for the first time the existence of two distinct EM states, each of which was characteristic of responders or non-responders, of WT1-specific CTLs in AML patients, and raises the possibility of using advanced gene-expression profile analysis to clearly discriminate between responders and non-responders prior to WT1 vaccination.

Wilms tumor 1 peptide vaccination combined with temozolomide against newly diagnosed glioblastoma: safety and impact on immunological response

To investigate the safety of combined Wilms tumor 1 peptide vaccination and temozolomide treatment of glioblastoma, a phase I clinical trial was designed. Seven patients with histological diagnosis of glioblastoma underwent concurrent radiotherapy and temozolomide therapy. Patients first received Wilms tumor 1 peptide vaccination 1 week after the end of combined concurrent radio/temozolomide therapy, and administration was continued once per week for 7 weeks. Temozolomide maintenance was started and performed for up to 24 cycles, and the observation period for safety encompassed 6 weeks from the first administration of maintenance temozolomide. All patients showed good tolerability during the observation period. Skin disorders, such as grade 1/2 injection-site reactions, were observed in all seven patients. Although grade 3 lymphocytopenia potentially due to concurrent radio/temozolomide therapy was observed in five patients (71.4 %), no other grade 3/4 hematological or neurological toxicities were observed. No autoimmune reactions were observed. All patients are still alive, and six are on Wilms tumor 1 peptide vaccination without progression, yielding a progression-free survival from histological diagnosis of 5.2-49.1 months. Wilms tumor 1 peptide vaccination was stopped in one patient after 12 injections by the patient's request. The safety profile of the combined Wilms tumor 1 peptide vaccination and temozolomide therapy approach for treating glioblastoma was confirmed.

Wilms tumor 1 (WT1) protein: Diagnostic utility in pediatric tumors

Despite Wilms tumor 1 (WT1) protein was originally considered as a specific immunomarker of Wilms tumor, with the increasing use of immunohistochemistry, there is evidence that other tumors may share WT1 protein expression. This review focuses on the immunohistochemical profile of WT1 protein in the most common malignant tumors of children and adolescents. The variable expression and distribution patterns (nuclear vs cytoplasmic) in the different tumors, dependent on the antibodies used (anti-C or N-terminus WT1 protein), will be emphasized by providing explicative illustrations. Potential diagnostic pitfalls from unexpected WT1 protein expression in some tumors will be discussed in order to avoid diagnostic errors, especially when dealing with small biopsies.

Transduction of a novel HLA-DRB1*04:05-restricted, WT1-specific TCR gene into human CD4+ T cells confers killing activity against human leukemia cells

BACKGROUND/AIM

Wilms' tumor gene 1 (WT1) product is a pan-tumor-associated antigen. We previously identified WT1 protein-derived promiscuous helper peptide, WT1332. Therefore, isolation and characterization of the WT1332-specific T-cell receptors (TCRs) are useful to develop broadly applicable TCR gene-based adoptive immunotherapy.

MATERIALS AND METHODS

A novel HLA-DRB1*04:05-restricted WT1332-specific TCR gene was cloned and transduced into human CD4+ T-cells by using a lentiviral vector.

RESULTS

The WT1332-specific TCR-transduced CD4+ T-cells showed strong proliferation and Th1-cytokine production in an HLA-DRB1*04:05-restricted, WT1332-specific manner. Furthermore, the WT1332-specific TCR-transduced CD4+ T-cells could lyse HLA-DRB1*04:05-positive, WT1-expressing leukemia cells in vitro.

CONCLUSION

The novel TCR gene cloned here should be a promising tool to develop adoptive immunotherapy of WT1332-specific TCR-transduced CD4+ T-cells for the treatment of WT1-expressing cancer, such as leukemia.

A single bout of dynamic exercise enhances the expansion of MAGE-A4 and PRAME-specific cytotoxic T-cells from healthy adults

The ex vivo expansion of tumor-associated-antigen (TAA)- specific cytotoxic T-cells (CTLs) from healthy donors for adoptive transfer to cancer patients is now providing additional treatment options for patients. Many studies have shown that adoptive transfer of expanded CTLs can reduce the risk of relapse in cancer patients following hematopoietic stem cell transplantation (HSCT). However, the procedure can be limited by difficulties in priming and expanding sufficient numbers of TAA-specific-CTLs. Because acute dynamic exercise mobilizes large numbers of T-cells to peripheral blood, we hypothesized that a single bout of exercise would augment the ex vivo expansion of TAA-specific-CTLs.We therefore collected lymphocytes from blood donated by healthy adults at rest and after brief maximal dynamic exercise. TAA-specific CTLs were expanded using autologous monocyte-derived-dendritic cells pulsed with melanoma-associated antigen 4 (MAGE-A4), with preferentially expressed antigen in melanoma (PRAME), and with Wilms' tumor protein (WT-1). Post exercise, 84% of the participants had a greater number of CTLs specific for at least one of the three TAA.Cells expanded from post exercise blood yielded a greater number of MAGE-A4 and PRAME-specific-cells in 70% and 61% of participants, respectively. In the 'exercise-responsive' participants (defined as participants with at least a 10% increase in TAA-specific-CTLs post-exercise), MAGEA4- and PRAME-specific-CTLs increased 3.4-fold and 6.2- fold respectively. Moreover, expanded TAA-specific CTLs retained their antigen-specific cytotoxic activity. No phenotype differences were observed between expanded cells donated at rest and postexercise. We conclude that exercise can enhance the ex vivo expansion of TAA-specific-CTLs from healthy adults without compromising cytotoxic function. Hence, this study has implications for immunotherapy using adoptive T-cell transfer of donor-derived T-cells after allogeneic HSCT.

Prognostic markers for patient outcome following vaccination with multiple MHC Class I/II-restricted WT1 peptide-pulsed dendritic cells plus chemotherapy for pancreatic cancer

BACKGROUND/AIM

Treatment combining dendritic cells (DCs) pulsed with three types of major histocompatibility complex (MHC) class I and II (DC/WT1-I/II)-restricted Wilms' tumor 1 (WT1) peptides with chemotherapy may stabilize disease in pancreatic cancer patients.

MATERIALS AND METHODS

Laboratory data from seven patients with pancreatic cancer who underwent combined DC/WT1-I/II vaccination and chemotherapy were analyzed. The DC phenotypes and plasma cytokine profiles were analyzed via flow cytometry.

RESULTS

The post-treatment neutrophil to lymphocyte (N/L) ratio was a treatment-related prognostic factor for better survival. Moreover, the mean fluorescence intensities (MFIs) of human leukocyte antigen (HLA)-DR and cluster of differentiation (CD)83 on DCs were significantly increased after chemoimmunotherapy. Interestingly, interleukin (IL)-6 level in plasma was significantly increased after chemoimmunotherapy in non-super-responders.

CONCLUSION

An increased N/L ratio, as well as HLA-DR and CD83 MFI levels may be prognostic markers of longer survival in patients with advanced pancreatic cancer who undergo chemoimmunotherapy.

[Adjuvant therapy with WT1 peptide-pulsed dendritic cell therapy in combination with TS-1 for pancreatic cancer with positive peritoneal cytology after curative operation]

A 66-year-old woman was diagnosed with pancreatic tail cancer, and she was referred to our hospital. Abdominal computed tomography(CT)revealed a tumor(2.5 cm in diameter)in the pancreatic tail, with invasion to the spleen and splenic vein. In February 2013, we performed distal pancreatectomy with splenectomy, left adrenal gland resection, and D2 lymph node dissection. Diagnostic peritoneal lavage cytology during surgery was positive; however, we performed curative resection because there were no signs of peritoneal dissemination and distant metastasis. The patient was discharged from the hospital 23 days after the operation, with good postoperative course. Histological diagnosis was pancreatic tail cancer, pT4N0H0P0M(-) fStage IVa. Subsequently, the patient received postoperative adjuvant chemotherapy(TS-1: 100mg/day, 4 courses)combined with Wilms'tumor 1(WT1)peptide-pulsed dendritic cell therapy. No serious adverse events occurred during the postoperative adjuvant therapy. The patient remains alive without recurrence 16 months after the operation.

[Efficacy of WT1 peptide-/MUC-1 peptide-pulsed dendritic cell therapy in 313 patients with a wide range of cancers]

We assessed the efficacy of Wilms' tumor protein-1(WT1)peptide and/or mucin 1(MUC-1)peptide-pulsed dendritic cell(DC)therapy for a wide range of advanced cancers.This retrospective study included 313 patients with advanced cancer who were vaccinated ≥5 times in our clinic between May 2009 and October 2013.T he clinical response was evaluated.This treatment was approved by the ethics panel of our institution.A total of 313 patients were injected an average of 6.0 times with DCs(2.4×10 / 7 cells/injection).Overall, 292 of the 313(93%)patients obtained clinical benefit according to the Response Evaluation Criteria in Solid Tumors(RECIST), version 1.1. The median survival time(MST)from diagnosis and from first being admitted to this institution was 28.4 months and 13.2 months, respectively. Complete response(CR)was achieved in 21 patients(7.2%).Partial response(PR)was achieved in 69 patients(24%).Stable disease(SD)was observed in 107 patients(37%), and progressive disease(PD)was observed in 95 patients(33%).The response rate(RR)and disease control rate(DCR)for each type of cancer were as follows: colorectal cancer(56 patients), 25%and 45%, respectively; lung cancer(39 patients), 31% and 82%, respectively; pancreatic cancer(36 patients), 22% and 64%, respectively; gastric cancer( 34 patients), 32% and 74%; breast cancer(20 patients), 15% and 75%, respectively; ovarian cancer(16 patients), 19% and 50%, respectively; esophageal cancer(15 patients), 20% and 73%, respectively; and others(76 patients), 38% and 67%.These results demonstrated the potential clinical effectiveness of DC-based immunotherapy.

WT1 Peptide-Based Immunotherapy for Patients with Lung Cancer: Report of Two Cases

The Wilms' tumor gene WT1 is overexpressed in various types of solid tumors, including lung and breast cancer and WT1 protein is a tumor antigen for these malignancies. In phase I clinical trials of WT1 peptide-based cancer immunotherapy, two patients with advanced lung cancer were intradermally injected with 0.3 mg of an HLA-A*2402-restricted, 9-mer WT1 peptide emulsified with Montanide ISA51 adjuvant. Consecutive WT1 vaccination at 2-week intervals resulted in a reduction in tumor markers such as chorio-embryonic antigen (CEA) and sialyl Lewis (x) (SLX) and by a transient decrease in tumor size. No adverse effects except for local erythema at the injection sites of WT1 vaccine were observed. These results provided us with the first clinical evidence demonstrating that WT1 peptide-based immunotherapy should be a promising treatment for patients with lung cancer.

Functional human Th17 clones with WT1-specific helper activity

Th17 plays important roles in the pathogenesis of various inflammatory and autoimmune diseases. Although the importance of Th17 in tumor immunity has also been suggested, precise roles of tumor-associated antigen-specific Th17 still remain poorly understood, especially in humans. We previously identified WT1332, a 16-mer helper epitope derived from tumor-associated antigen Wilms' tumor gene 1 (WT1) product, and WT1332-specific Th1 clones were established. In the present study, WT1-specific Th17 clones were established by the stimulation of peripheral blood mononuclear cells with the WT1332 helper peptide under human Th17-polarizing conditions. The WT1-specific Th17 clone exhibited the helper function for proliferation of conventional CD4(+) T cells in the antigenic stimulation-specific manner. This is the first report of establishment of functional Th17 clones with both antigen (WT1332) specificity and antigen-specific helper activity. Th17 clones established here and the method to establish antigen-specific Th17 clones should be a useful tool to further analyze the roles of human Th17 in tumor immunity.

Serial measurement of WT1 expression and decrement ratio until hematopoietic cell transplantation as a marker of residual disease in patients with cytogenetically normal acute myelogenous leukemia

Using real-time quantitative PCR, we monitored Wilms tumor gene 1 (WT1) expression from diagnosis to hematopoietic stem cell transplantation (HSCT) in adult patients with cytogenetically normal acute myelogenous leukemia (CN-AML) and FLT3-ITD and NPM1 mutations. The values at diagnosis were evaluated in 104 patients. Data collected after induction chemotherapy were available for all patients, but only 68 patients were treated with HSCT. Significant WT1 expression cut-offs were determined by receiver operation characteristic curve analysis, and rates of overall survival (OS) and disease-free survival (DFS) were estimated. WT1 decrement ratios (DR) at postinduction chemotherapy and at pre- and post-HSCT compared with the diagnostic level were calculated. Higher WT1 expression at diagnosis, postinduction chemotherapy, and pre-HSCT showed inferior OS (P = .015, <.001, and .002) and DFS (P = .006, <.001, and .003). The cut-offs were determined at the median for diagnostic WT1 expression and at the 25% level from the top for other time points excluding post-HSCT. The WT1 DR ≥ 1-log after induction chemotherapy showed superior OS and DFS (P = .009 and .002) and WT1 DR ≥ 1-log preceding HSCT also showed superior OS and DFS (P = .009 and .003). Results of WT1 DR were consistently applicable in each subgroup with higher (≥ 1.0) and lower (<1.0) WT1 expression at diagnosis and also in NPM1-wild-type/FLT3-ITD-negative CN-AML. The WT1 DR therefore predicted survival outcomes after HSCT more accurately than did the diagnostic WT1 expression. WT1 expression may serve as a reliable marker for residual disease and WT1 DR as a prognostic indicator, particularly in NPM1-wild-type/FLT3-ITD-negative CN-AML. These measures may be applied throughout the course of treatment and even after HSCT.

Recognition of a natural WT1 epitope by a modified WT1 peptide-specific T-cell receptor

Wilms' tumor gene WT1 is highly expressed in leukemia and in various types of solid tumors and exerts an oncogenic function. Thus, WT1 protein is a most promising tumor-associated antigen. We have been successfully performing WT1 vaccination with a 9-mer modified WT1(235) peptide, which has one amino acid substitution (M→Y) at position 2 of 9-mer natural WT1(235) peptide (235-243 a.a.), for close to 700 HLA-A*24:02-positive patients with leukemia or solid tumors. Although vaccination of modified WT1(235) peptide induced natural WT1(235) peptide-recognizing cytotoxic T-lymphocytes (CTLs) and exerted cytotoxic activity towards leukemia and solid tumor cells that expressed the natural WT1(235) peptide (epitope) but not the vaccinated modified WT1(235) peptide (epitope), the molecular basis has remained unclear. In this study, we established a modified WT1(235) peptide-specific CTL clone, we isolated T-cell receptor (TCR) genes from it and transduced the TCR genes into CD8(+) T-cells. The TCR-transduced CD8(+) T-cells produced interferon-γ (IFNγ) and tumor necrosis factor-α (TNFα) in response to stimulation not only with the modified WT1(235) peptide but also with the natural WT1(235) peptide and lysed modified or natural WT1(235) peptide-pulsed target cells and endogenously WT1-expressing leukemia cells in a HLA-A*24:02-restriction manner. These results provided us, for the first time at molecular basis, with a proof-of-concept of modified WT1(235) peptide-based immunotherapy for natural WT1(235) peptide-expressing malignancies.

[WT1-targeting cancer vaccine]

Wilms' tumor gene WT1 encodes a transcription factor and functions as an oncogene. WT1 gene product WT1 protein is a promising par-tumor-associated antigen. WT1 peptide-based immunotherapy has been performing for more than six hundred patients with leukemias and various types of solid tumors. This immunotherapy is safe and has clinical benefit especially for leukemia, glioblastoma multiforme, advanced pancreatic cancer, and ovarian cancer. As a new strategy for cancer treatment, it should be recommended to initiate immunotherapy that had a potential of eradication of cancer stem cells before surgery, chemo- and radio-therapy.

[Prediction of WT1/MUC1 peptide dendritic cell therapy responders by quantification of ex vivo induced mRNA in whole blood]

Cancer immunotherapy has shown much potential, but is not yet beneficial for all patients. Acquired immunity after immunotherapy can be assessed by a variety of methods; however, the methods for the prediction of such responses before treatment are quite limited. To challenge this classic problem, we quantified 17 different leukocyte function-associated mRNAs( IFN-γ,TNFSF1, TNFSF2, TNFSF5, IL-10, TGF β,CTLA4, PD1, FOXP3, GMCSF, VEGF, IL-8, CCL8, CXCL3, and IL-2) in whole blood after ex vivo stimulation with 7 different agents(PHA, HAG, zymosan, IFN-γ,rIL-2, aTCR, and picibanil) to activate various subsets of leukocytes. The mRNAs were quantified by the Hitachi Chemical Research Center, Inc. Irvine, CA. The clinical outcomes for WT1 peptide-and/or MUC1 peptide-pulsed dendritic cell therapy for advanced cancer (n=26) were CR+PR, 4 cases; SD, 9 cases; and PD, 13 cases. The accuracy of prediction was found to be 100% using the formula developed by multivariate discriminant analysis of the values for ex vivo induced mRNAs. Because the volume of blood needed for this test is less than 1.5 mL, and because cell isolation and culture are not necessary, this method will become a model of personalized medicine diagnostics for cancer immunotherapy.

Phase I trial of Wilms' Tumor 1 (WT1) peptide vaccine with GM-CSF or CpG in patients with solid malignancy

BACKGROUND

The aim of this study was to investigate the safety and efficacy of combinatorial use of granulocyte-macrophage colony-stimulating factor (GM-CSF) and CpG oligodeoxynucleotides (CpG-ODN) as immunoenhancement adjuvants in Wilms' Tumor 1 (WT1) vaccine therapy for patients with solid malignancy.

PATIENTS AND METHODS

The patients were placed into treatment groups as follows: WT1 peptide alone, WT1 peptide with GM-CSF (100 μg) and WT1 peptide with CpG-ODN (100 μg). HLA-A *2402 or *0201/*0206-restricted, WT1 peptide emulsified with Montanide ISA51 was injected intradermally every week for eight weeks. Toxicities were evaluated according to the National Cancer Institute Common Terminology Criteria for Adverse Events ver. 3.0. Tumor size, which was measured by computed tomography, was determined every four weeks. The responses were analyzed according to Response Evaluation Criteria in Solid Tumors.

RESULTS

The protocol was well tolerated; only local erythema occurred at the WT1 vaccine injection site. The disease control rate of the groups treated with WT1 peptide alone (n=10), with combinatorial use of GM-CSF (n=8) and with combinatorial use of CpG-ODN (n=10), in the initial two months was 20%, 25% and 60%, respectively.

CONCLUSION

Addition of GM-CSF or CpG-ODN to the WT1 peptide vaccine for patients with solid malignancy was safe and improved the effectiveness of clinical response.

Wilms' tumor protein 1 (WT1) peptide vaccination in AML patients: predominant TCR CDR3β sequence associated with remission in one patient is detectable in other vaccinated patients

BACKGROUND

Clinically effective T-cell responses can be elicited by single peptide vaccination with Wilms' tumor 1 (WT1) epitope 126-134 in patients with acute myeloid leukemia (AML). We recently showed that a predominant T-cell receptor (TCR) β chain was associated with vaccine-induced complete remission in an AML patient (patient 1). In this study, we address the question of whether this predominant clone or the accompanying Vβ11 restriction could be found in other AML patients vaccinated with the same WT1 peptide.

MATERIALS AND METHODS

For assessment of Vβ usage, cytotoxic T lymphocytes (CTLs) from four vaccinated patients were divided into specific and non-specific by epitope-specific enrichment. Vβ families were quantified in both fractions using reverse transcribed quantitative PCR. Vβ11-positive 'complementary determining region 3' (CDR3) sequences were amplified from these samples, from bone marrow samples of 17 other vaccination patients, and from peripheral blood of six healthy controls, cloned and sequenced.

RESULTS

We observed a clear bias towards Vβ11 usage of the WT1-specific CTL populations in all four patients. The predominant CDR3β amino acid (AA) sequence of patient 1 was detected in two other patients. CDR3β loops with closely related AA sequences were only found in patient 1. There were no CDR3β AA sequences with side chains of identical chemical properties detected in any patient.

CONCLUSION

We provide the first data addressing TCR Vβ chain usage in WT1-specific T-cell populations after HLA A*0201-restricted single peptide vaccination. We demonstrate both shared Vβ restriction and the sharing of a TCR β transcript with proven clinical impact in one patient.

Active specific immunotherapy targeting the Wilms' tumor protein 1 (WT1) for patients with hematological malignancies and solid tumors: lessons from early clinical trials

There is a growing body of evidence that Wilms' tumor protein 1 (WT1) is a promising tumor antigen for the development of a novel class of universal cancer vaccines. Recently, in a National Cancer Institute prioritization project, WT1 was ranked first in a list of 75 cancer antigens. In this light, we exhaustively reviewed all published cancer vaccine trials reporting on WT1-targeted active specific immunotherapy in patients with hematological malignancies and solid tumors. In all clinical trials, vaccine-induced immunological responses could be detected. Importantly, objective clinical responses (including stable disease) were observed in 46% and 64% of evaluable vaccinated patients with solid tumors and hematological malignancies, respectively. Immunogenicity of WT1-based cancer vaccines was demonstrated by the detection of a specific immunological response in 35% and 68% of evaluable patients with solid tumors and hematological malignancies, respectively. In order to become part of the armamentarium of the modern oncologist, it will be important to design WT1-based immunotherapies applicable to a large patient population, to standardize vaccination protocols enabling systematic review, and to further optimize the immunostimulatory capacity of the vaccine components. Moreover, improved immunomonitoring tools that reveal clinically relevant T-cell responses will further shape the ideal WT1 immunotherapy strategy. In conclusion, the clinical results obtained so far in WT1-targeted cancer vaccine trials reveal an untapped potential for inducing cancer immunity with minimal side effects and hold promise for a new adjuvant treatment against residual disease and against cancer relapse.

Gemcitabine enhances Wilms' tumor gene WT1 expression and sensitizes human pancreatic cancer cells with WT1-specific T-cell-mediated antitumor immune response

Wilms' tumor gene (WT1), which is expressed in human pancreatic cancer (PC), is a unique tumor antigen recognized by T-cell-mediated antitumor immune response. Gemcitabine (GEM), a standard therapeutic drug for PC, was examined for the regulation of WT1 expression and the sensitizing effect on PC cells with WT1-specific antitumor immune response. Expression of WT1 was examined by quantitative PCR, immunoblot analysis, and confocal microscopy. Antigenic peptide of WT1 presented on HLA class I molecules was detected by mass spectrometry. WT1-specific T-cell receptor gene-transduced human T cells were used as effecter T cells for the analysis of cytotoxic activity. GEM treatment of human MIAPaCa2 PC cells enhanced WT1 mRNA levels, and this increase is associated with nuclear factor kappa B activation. Tumor tissue from GEM-treated MIAPaCa2-bearing SCID mice also showed an increase in WT1 mRNA. Some human PC cell lines other than MIAPaCa2 showed up-regulation of WT1 mRNA levels following GEM treatment. GEM treatment shifted WT1 protein from the nucleus to the cytoplasm, which may promote proteasomal processing of WT1 protein and generation of antigenic peptide. In fact, presentation of HLA-A*2402-restricted antigenic peptide of WT1 (CMTWNQMNL) increased in GEM-treated MIAPaCa2 cells relative to untreated cells. WT1-specific cytotoxic T cells killed MIAPaCa2 cells treated with an optimal dose of GEM more efficiently than untreated MIAPaCa2 cells. GEM enhanced WT1 expression in human PC cells and sensitized PC cells with WT1-specific T-cell-mediated antitumor immune response.

Allogeneic HLA-A*02-restricted WT1-specific T cells from mismatched donors are highly reactive but show off-target promiscuity

T cells recognizing tumor-associated Ags such as Wilms tumor protein (WT1) are thought to exert potent antitumor reactivity. However, no consistent high-avidity T cell responses have been demonstrated in vaccination studies with WT1 as target in cancer immunotherapy. The aim of this study was to investigate the possible role of negative thymic selection on the avidity and specificity of T cells directed against self-antigens. T cell clones directed against the HLA-A*0201-binding WT1(126-134) peptide were generated from both HLA-A*02-positive (self-HLA-restricted) and HLA-A*02-negative [nonself (allogeneic) HLA [allo-HLA]-restricted] individuals by direct ex vivo isolation using tetramers or after in vitro priming and selection. The functional avidity and specificity of these T cell clones was analyzed in-depth. Self-HLA-restricted WT1-specific clones only recognized WT1(126-134) with low avidities. In contrast, allo-HLA-restricted WT1 clones exhibited profound functional reactivity against a multitude of HLA-A*02-positive targets, even in the absence of exogenously loaded WT1 peptide, indicative of Ag-binding promiscuity. To characterize this potential promiscuity, reactivity of the T cell clones against 400 randomly selected HLA-A*0201-binding peptides was investigated. The self-HLA-restricted WT1-specific T cell clones only recognized the WT1 peptide. In contrast, the allo-HLA-restricted WT1-reactive clones recognized besides WT1 various other HLA-A*0201-binding peptides. In conclusion, allogeneic HLA-A*02-restricted WT1-specific T cells isolated from mismatched donors may be more tumor-reactive than their autologous counterparts but can show specific off-target promiscuity of potential clinical importance. As a result of this, administration of WT1-specific T cells generated from HLA-mismatched donors should be performed with appropriate precautions against potential off-target effects.

WT1 peptide vaccine stabilized intractable ovarian cancer patient for one year: a case report

We report on Wilms tumor (WT1) peptide immunotherapy in a patient with intractable ovarian cancer patient over an extended period.

CASE REPORT

Immunotherapy using WT1 peptide has been undergoing clinical trials for gynecological cancer. We used WT1 peptide vaccination to treat a 53-year-old woman suffering from ovarian cancer with peritoneal dissemination. After 2 months, her pleural and cardiac effusion had disappeared, and the sum of the longest diameter of the target lesion (in the pelvic mass) was reduced. There was a weak positive correlation between CA125 and mononuclear phagocyte/lymphocyte ratio (Spearman's ϱ=0.275, p=0.015). Intradermally administered WT1 peptide vaccination in a case of intractable ovarian cancer stabilized the disease over the course of one year. However, the immunotherapeutic mechanism of WT1 peptide and immunological escape mechanism for carcinoma cells remain to be elucidated.

Frequency of myeloid dendritic cells can predict the efficacy of Wilms' tumor 1 peptide vaccination

BACKGROUND

The object of this study was to investigate the clinical predictive capability of peripheral myeloid dendritic cells (DCs) in Wilms' tumor 1 (WT1) vaccine therapy for patients with gynaecological cancer.

PATIENTS AND METHODS

Six patients with WT1/human leukocyte antigen (HLA)-A*2402-positive gynaecological cancer were included in this study. The patients received intradermal injections of a modified 9-mer WT1 peptide every week for 12 weeks. Peripheral blood samples were obtained at 0, 4, 8 and 12 weeks after the initial vaccination. Circulating DCs were detected by flow cytometry.

RESULTS

The frequencies of CD14(+)CD16(+)CD33(+)CD85(+) myeloid DCs were significantly higher in the therapeutically effective group than in therapeutically inert group (p<0.05).

CONCLUSION

These results suggested that myeloid DCs, which should be associated with inducing cytotoxic T-cells, provided additional prognostic information in the use of cancer peptide vaccine.

[Construction of fusion gene vaccine of WT1 multi-epitope fused with stimulating epitope of mycobacterium tuberculosis heat shock protein 70 and its expression and immunogenicity]

This study was purposed to construct a fusion DNA vaccine containing WT1 multi-epitope and stimulating epitope of mycobacterium tuberculosis heat shock protein 70 and to detect its expression and immunogenicity. On the basis of published data, a multi-epitope gene (Multi-WT1) containing three HLA *0201-restricted CTL epitopes: one HLA*2402-restricted CTL epitope, two Th epitopes and one universal Th Pan-DR epitope (PADRE) was constructed. DNA-coding sequence was modified by Computer-Aided Design (CAD) to optimize proteasome-mediated epitope processing through the introduction of different amino acid spacer sequences. The synthetic nucleotide sequence was then inserted into an eukaryotic vector to construct the plasmid pcDNA3.1-WT1.For enhancing CTL activity, HSP70 fragment including stimulatory domain P407-426 was amplified by PCR from mycobacterial HSP70 gene and cloned into pcDNA3.1(+). Then Multi-WT1 was fused to the N-terminal of pcDNA3.1-mHSP70(407-426) to make the multi-epitope fusion gene vaccine pcDNA3.1-WT1-mHSP70(407-426). HEK-293T cells were transfected with this vaccine and the expressed product was identified by RT-PCR. Enzyme-linked immunospot assay (ELISPOT) was used to evaluate the immunological responses elicited by vaccine. The results showed that the most of WT1 epitopes could be correctly cleaved which was confirmed by software Net Chop 3.1 and PAPROCIanalysis. RT-PCR showed correct expression of target gene in HEK293T cells and ELISPOT showed specific T-cell responses. It is concluded that the eukaryotic expression vector PcDNA3.1-WT1-mHSP70(407-426) fusion gene has been successfully constructed and the immunity response is also elicited, which is a good candidate for further research of DNA vaccine.

T-cell immune responses to Wilms tumor 1 protein in myelodysplasia responsive to immunosuppressive therapy

Clinical observations and laboratory evidence link bone marrow failure in myelodysplastic syndrome (MDS) to a T cell-mediated immune process that is responsive to immunosuppressive treatment (IST) in some patients. Previously, we showed that trisomy 8 MDS patients had clonally expanded CD8(+) T-cell populations that recognized aneuploid hematopoietic progenitor cells (HPC). Furthermore, microarray analyses showed that Wilms tumor 1 (WT1) gene was overexpressed by trisomy 8 hematopoietic progenitor (CD34(+)) cells compared with CD34(+) cells from healthy donors. Here, we show that WT1 mRNA expression is up-regulated in the bone marrow mononuclear cells of MDS patients with trisomy 8 relative to healthy controls and non-trisomy 8 MDS; WT1 protein levels were also significantly elevated. In addition, using a combination of physical and functional assays to detect the presence and reactivity of specific T cells, respectively, we demonstrate that IST-responsive MDS patients exhibit significant CD4(+) and CD8(+) T-cell responses directed against WT1. Finally, WT1-specific CD8(+) T cells were present within expanded T-cell receptor Vβ subfamilies and inhibited hematopoiesis when added to autologous patient bone marrow cells in culture. Thus, our results suggest that WT1 is one of the antigens that triggers T cell-mediated myelosuppression in MDS.

[WT1 peptide pulsed dendritic cell therapy with activated T lymphocytes therapy for advanced cancers]

We assessed the efficacy of WT1 peptide pulsed dendritic cell (DC) therapy for various advanced cancers. All patients were vaccinated 5 times for 10 weeks with autologous monocytes derived DC and activated T lymphocytes. We treated a total of 26 patients who had HLA-A2402 or/and HLA-A0201. We evaluated 20 of the 26 patients who finished 5-time vaccination (10 men and 10 women, aged 48-81 years, Mean 64 years) and were diagnosed as follows: 3-pancreas cancer, 2-colorectal, 2-breast, 2-esophageal, 2-lung, 2-uterus, 2-ovarian and 5 others. In Clinical response (RECIST), the result was assessed as CR/PR/SD/PD, 0/7/8/5, respectively. Furthermore, the 7 PRs were resulted from 2-colorectal, and one of each was lung, laryngeal, axis, pancreas and smooth muscle sarcoma cancer. The 4 of 7 PR patients were treated with chemotherapy.

Wilms' tumor protein Wt1 regulates the Interleukin-10 (IL-10) gene

We identified the Wilms' tumor protein, Wt1, as a novel transcriptional activator of the immunosuppressant cytokine interleukin-10 (IL-10). Silencing of Wt1 by RNA interference reduced IL-10 mRNA levels by approximately 90%. IL-10 transcripts were increased more than 15-fold upon forced expression of Wt1. Electrophoretic mobility shift assay and chromatin immunoprecipitation revealed a cis-element that was responsible for activation of the IL-10 promoter by Wt1 in murine macrophages. Mutation of the Wt1 binding motif abrogated stimulation of the IL-10 promoter by tumor necrosis factor-α (TNFα). These results suggest a novel immune regulatory function of Wt1 in controlling IL-10 gene expression.

Immunological response after therapeutic vaccination with WT1 mRNA-loaded dendritic cells in end-stage endometrial carcinoma

BACKGROUND

Wilms' tumour gene 1 (WT1), a highly ranked immunotherapeutic target, is expressed in uterine cancer and therefore WT1 immunotherapy may present an attractive treatment option.

PATIENT AND METHODS

An HLA-A2.1-positive 46-year-old woman with end-stage serous endometrial cancer received 4 weekly injections of WT1-RNA-loaded dendritic cells. Response was measured clinically (CT scan), biochemically (CA125) and immunologically (WT1-specific T cells).

RESULTS

The patient showed WT1 positivity in 10% of tumour cells and diffusely in the intratumoural endothelial cells of the recurrent disease. After 2 injections, CA125 started to decrease and WT1-specific T-cells increased 2.5-fold. The treatment was feasible and there were no treatment-related side-effects. However, the patient, suffering from diffuse disease which became progressive again, died 8 months later.

CONCLUSION

This is the first patient with a WT1-positive endometrial carcinoma, to receive immunotherapy with WT1-RNA-loaded dendritic cells, resulting in a vaccine-specific T cell response.

Induction of complete and molecular remissions in acute myeloid leukemia by Wilms' tumor 1 antigen-targeted dendritic cell vaccination

Active immunization using tumor antigen-loaded dendritic cells holds promise for the adjuvant treatment of cancer to eradicate or control residual disease, but so far, most dendritic cell trials have been performed in end-stage cancer patients with high tumor loads. Here, in a phase I/II trial, we investigated the effect of autologous dendritic cell vaccination in 10 patients with acute myeloid leukemia (AML). The Wilms' tumor 1 protein (WT1), a nearly universal tumor antigen, was chosen as an immunotherapeutic target because of its established role in leukemogenesis and superior immunogenic characteristics. Two patients in partial remission after chemotherapy were brought into complete remission after intradermal administration of full-length WT1 mRNA-electroporated dendritic cells. In these two patients and three other patients who were in complete remission, the AML-associated tumor marker returned to normal after dendritic cell vaccination, compatible with the induction of molecular remission. Clinical responses were correlated with vaccine-associated increases in WT1-specific CD8+ T cell frequencies, as detected by peptide/HLA-A*0201 tetramer staining, and elevated levels of activated natural killer cells postvaccination. Furthermore, vaccinated patients showed increased levels of WT1-specific IFN-gamma-producing CD8+ T cells and features of general immune activation. These data support the further development of vaccination with WT1 mRNA-loaded dendritic cells as a postremission treatment to prevent full relapse in AML patients.

A clear correlation between WT1-specific Th response and clinical response in WT1 CTL epitope vaccination

Clinical studies of WT1-targeted cancer vaccine are being performed. However, WT1-specific Th response in cancer patients remains unclear. Using quantitative real-time RT-PCR, we investigated IFN-gamma and IL-10 mRNA expression from Th cells by stimulation with helper peptide WT1(332). Seventeen patients, of whom 10 had achieved stable disease and the remaining 7 had progressive disease, were weekly vaccinated with WT1 CTL epitope (modified WT1(235)) and examined for WT1(332)-specific Th response. A clear correlation between WT1(332)-specific Th response and clinical response was observed at 4 weeks post-vaccination. In patients who responded, a clear inverse correlation between IL-10-type and IFN-gamma-type WT1(332)-specific Th response was detected at pre- and 4 weeks post-vaccination, and the shift of the Th response from IL-10-type dominancy at early phase to IFN-gamma-type dominancy at late phase was observed. From this study we concluded that occurrence of WT1(332)-specific Th response could predict good clinical response of WT1 CTL epitope vaccination.