Table of Contents
1. What is the WT1 Anti-Cancer Peptide
2. Clinical Evidence Related to WT1
3. Approval Status by International Regulatory Bodies
4. WT1 Injection Process
1. What is the WT1 Anti-Cancer Peptide
Background 1: Alarming Cancer Incidence Rates in China
China has entered a high-incidence phase of cancer. In February 2022, the National
Cancer Center released the latest national cancer statistics, showing:
• 4.064 million new cases
• 2.414 million deaths
• More than 7 people diagnosed with cancer every minute on average.
Background 2: Evolution of Cancer Treatment Methods
• Surgery
• Radiotherapy
• Chemotherapy
• Hormone Therapy
• Targeted Therapy
Tumor Immunotherapy: History and Prospects
1. Bacterial toxin treatment for tumors
2. First human tumor-associated TAA (tumor-associated antigen)
3. Provenge approved by FDA
4. New antigens against cancer: Peptides, mRNA
5. DC cells: Development of mRNA tumor immune prevention by 2030, potentially FDA approved.
The Importance of Synthetic Peptides
• Nearly all cancer cells have genetic alterations (missense, deletions, frameshift,
and gene fusion mutations), leading to tumor neo-epitopes.
• Preparing personalized tumor prevention candidate new antigens.
2. Clinical Evidence Related to WT1
• WT1 is highly expressed in more than twenty types of cancers including both
hematological and solid tumors.
• WT1 peptide can be used for dendritic cell immunotherapy for nearly all cancers.
• Studies and clinical trials show that WT1 peptides are safe and tolerable for almost
all patients with late-stage malignant tumors, achieving significant therapeutic effects.
Examples of Cancer Types Treated:
• Acute Myeloid Leukemia (AML)
• Acute Lymphoblastic Leukemia (ALL)
• Esophageal Cancer
• Chronic Myeloid Leukemia (CML)
• Gastric Cancer
• Pancreatic Cancer
• Gallbladder and Bile Duct Cancer
• Multiple Myeloma
• Colorectal Cancer
• Brain Tumors
• Renal Cancer
• Bladder Cancer
• Gynecological Tumors
• Malignant Melanoma
Clinical Outcomes:
• Complete remission observed in some acute myeloid leukemia patients after WT1 peptide vaccination.
• WT1-specific antibodies induced and maintained in patients.
3. Approval Status by International Regulatory Bodies
• WT1 vaccines (Galinpepimut-S, DSP-7888) are in various clinical stages in the US
and Japan.
• FDA and EU have designated WT1 as an “orphan drug,” granting policy and financial
support for its development.
4. WT1 Injection Process At this time, our Chief Scientist and his team are conducting trials in Hong Kong and China.
Package Description:
• Three injections over six months, with appointments in Hong Kong.
Service Flow and Advantages:
• Comprehensive health assessment in Shenzhen or through provided reports.
• VIP service to Hong Kong with professional medical consultation and follow-ups.
WT1 (Wilms’ Tumor Gene 1): Biology and Cancer Immunotherapy
Haruo Sugiyama*
Osaka University Graduate School of Medicine, Osaka, Japan
*For reprints and all correspondence: Haruo Sugiyama, Osaka University Graduate School of Medicine, Department of Functional Diagnostic Science, Osaka 565-0871, Japan. E-mail: sugiyama@sahs.med.osaka-u.ac.jb
Wilms’ tumor gene WT1 encodes a transcription factor and plays an important role in cell growth and differentiation. The WT1 gene is highly expressed in leukemia and various types of solid tumors, whereas WT1 is a tumor marker convenient for the detection of minimal residual disease of leukemia. The WT1 gene was originally defined as a tumor suppressor gene, but we proposed that it was, on the contrary, an oncogene. Furthermore, the WT1 protein has proven to be a promising tumor-associated antigen, in which many human leukocyte antigen class I- or II-restricted WT1 epitopes have been identified. Clinical trials of WT1-targeted immu- notherapy have confirmed its safety and clinical efficacy. WT1-specific cytotoxic T lymphocytes and WT1 antibodies are spontaneously induced in tumor-bearing patients, probably because of high immunogenicity of the WT1 protein. WT1-specific cytotoxic T lymphocytes make a major contribution to the graft-versus-leukemia effect after allogenic stem cell transplantation. When 75 cancer antigens including WT1 were prioritized according to several criteria such as thera- peutic function and immunogenicity, WT1 was ranked as the top antigen. These findings suggest that a new era of WT1 immunotherapy is imminent.
WILMS’ TUMOR GENE (WT1)
The WT1 gene was isolated as the gene responsible for a childhood renal neoplasm, Wilms’ tumor, which was thought to arise as a result of inactivation of both alleles of the WT1 gene located at chromosome 11p13 (1,2). This gene encodes a zinc finger transcription factor that plays an important role in cell growth and differentiation (3) and its expression is restricted to a limited set of tissues, including the gonad, uterus, kidney and mesothelium, and to progenitor cells in various types of tissues (4–6). WT1 knock-out mice were found to have defects in the urogenital system and died on ED 13.5, probably due to heart failure (7).
HIGH EXPRESSION OF THE WT1 GENE IN LEUKEMIAS AND SOLID TUMORS
The WT1 gene is highly expressed in the majority of acute myeloid leukemias (AML) and acute lymphoid leukemias (ALL) (Fig. 1) (8 – 18). This makes WT1mRNA a tumor marker for leukemic blast cells and one leukemic cell in. 100 000 normal peripheral blood mononuclear cells (PBMCs) can be detected by quantitation of WT1mRNA (WT1 assay) (10). In chronic myelogenous leukemia (CML) (10) and myelodysplastic syndrome (MDS) (19), WT1mRNA expression levels were seen to increase along with disease progression. The WT1 assay is currently con- sidered to be an essential test managing acute leukemia and MDS by means of detection of minimal residual disease (MRD) of leukemia. The WT1 gene is also expressed at high levels in almost all types of solid tumors (20–32), with its expression level serving as a significant prognostic factor.
THE WT1 GENE PERFORMS AN ONCOGENIC RATHER THAN TUMOR SUPPRESSOR ONE FUNCTION
The WT1 gene was originally defined as a tumor suppressor gene (33 – 38), but we proposed, on the basis of the accumu- lating evidence, that the WT1 gene plays an oncogenic func- tion in leukemogenesis and tumorigenesis (39). For example, growth of WT1-expressing leukemic and solid cancer cells.
was inhibited by treatment with WT1 antisense oligomers (40,41) and WT1-specific siRNA (42). Conversely, forced expression of the WT1 gene promoted cell growth (43 – 45) and motility (46), suppressed apoptosis (47) and induced leu- kemia in WT1-transgenic mice (48). WT1mRNA expression levels in human leukemic cells and human normal CD34þ hematopoietic progenitor cells (HPCs) were comparatively determined at single-cell level by using single-cell reverse transcriptase – polymerase chain reaction methods (49). Surprisingly, 1.2% of the CD34þ HPCs expressed WT1mRNA at levels similar to those in leukemic cells. These results indicated that WT1-expressing CD34þ HPCs are the normal counterparts of leukemic cells and that leukemic cells are mainly generated as a result of leukemic transformation of the WT1-expressing CD34þ HPCs. Since it is known that pro- genitor cells of various types of tissues express WT1 (50), we hypothesized that WT1-expressing progenitor cells can differ- entiate into tissue-specific cells by down-regulation of WT1 expression, but that if this down-regulation is impaired, WT1-expressing progenitor cells continue to proliferate and transform as a result of occurrence of secondary, tertiary or further genetic events.
WT1 PROTEIN AS A TUMOR REJECTION ANTIGEN
High expression of the WT1 gene in leukemias and solid tumors indicated that the WT1 protein might be a promising
tumor-associated antigen (TAA). Therefore, the murine WT1 protein-derived, MHC class I-restricted, 9-mer WT1 peptides Db126 (aa 126 – 134), Db227 (aa 227 – 235) and Db 235 (aa 235 – 243) were tested for their ability to induce WT1-specific cytotoxic T lymphocytes (CTLs) in a mouse model (51,52). The immunized mice rejected the challenges with WT1-expressing leukemic cells and survived, but showed no histopathological damage of organs that physio- logically expressed WT1. Gaiger et al. (53) reported that immunization with the murine MHC class I-binding WT1 peptides p136 – 144, p235 – 243 and p117 – 139 induced WT1-specific CTLs in mice and lysed WT1-expressing tumor cells, while no evidence of autoimmune toxicity was observed. Finally, Gao et al. (54) showed that CML CD34þ cells exposed to WT1-specific CTLs failed to develop leuke- mia in the recipient severe combined immunodeficiency mice, but CTL treatment did not inhibit engraftment of normal CD34þ HPCs. These findings indicated that the WT1 protein could well be an attractive tumor rejection antigen.
CLINICAL STUDY OF WT1-TARGETED CANCER IMMUNOTHERAPY
PHASE I CLINICAL STUDY
A Phase I clinical study of cancer immunotherapy targeting WT1 protein was initiated in 2001. Patients with AML, MDS, lung or breast cancer were intradermally injected with an HLA-A*2402-restricted natural (CMTWNQMNL) or modified (-Y——-) 9-mer WT1 peptide emulsified with Montanide ISA51 adjuvant at 0.3, 1.0 or 3.0 mg/body at 2-week intervals, after which toxicity and clinical and immunological responses were assessed (Table 1) (72 – 74). The WT1 vaccination was administered to 26 patients. In patients with breast or lung cancer or AML with adequate normal hematopoiesis, toxicity was detected only as local
erythema at the WT1 vaccine injection sites (72), whereas severe leukocytopenia occurred as the result of only a single dose of 0.3 mg of modified WT1 peptide in both MDS patients (Fig. 3) (73). This severe leukocytopenia was thought to have resulted from an attack by WT1-specific CTLs against WT1-expressing transformed HPCs, from which almost all leukocytes were derived. As expected, de novo AML in complete remission with sufficient normal hematopoiesis remaining, no leukocytopenia occurred because normal HPCs were not attacked by WT1-specific CTLs. Both breast cancer patients and three of eight lung cancer patients who were WT1-vaccinated showed clinical effects such as regression of tumor masses and a decrease in tumor markers. These early clinical studies confirmed both the safety and clinical effectiveness of WT1 peptide immunotherapy for patients with adequate normal hemato- poiesis and indicated the advisability of reducing the dose of WT1 peptide vaccine for patients with stem cell leukemia such as MDS and CML. In these patients, the majority of the hematopoietic cells were derived from WT1-expressing transformed HPCs and normal hematopoiesis was very poor (Fig. 4). Mailander et al. (75) vaccinated HLA-A*-0201- positive AML patients with 30% blasts in BM with WT1 peptide (aa 126 – 134) at a dose of 0.2 mg admixed with 1.0 mg of keyhole limpet hemocyanin, and injected granulo- cyte macrophage colony-stimulating factor at the same sites as those of the WT1 vaccine. Ten weeks after the vaccination, BM analysis showed that blasts accounted for less than 5% of cells and complete hematological remission was confirmed 16 weeks after the WT1 vaccination.
