Adoptive cell therapy for malignant mesothelioma and other mesothelin expressing

Division Of Basic Sciences - Nci

Investigators

Linked publications, trials & patents

Abstract

The overall goal of our program is to develop effective therapies for patients with solid tumors. This includes therapies directed to the tumor antigen mesothelin, that is overexpressed in many solid tumors. Our work is also focused on early cancer detection in patients who have germline mutation in the BAP1 gene that predisposes them to many different types of cancer. 1. Exploiting mesothelin for treatment of mesothelioma and other solid tumors Our current studies are focused on developing adoptive cell therapies directed against the tumor differentiation antigen mesothelin, which is expressed on normal mesothelial cells lining the pleura, pericardium, and peritoneum, but is highly expressed in several human tumors especially mesothelioma, ovarian cancer, lung cancer and pancreatic adenocarcinomas. This differential expression of mesothelin makes it an attractive candidate for tumor specific therapy. The majority of the anti-mesothelin antibodies in clinical development of immunotherapies including CAR-T cell therapies, target the immunogenic membrane-distal region of mesothelin which is prone to shedding and may act as a sink, thereby reducing the cell-killing activity. This domain is also the binding site for other proteins such as MUC1 that may compete with CAR T cell binding. We have developed anti-mesothelin CAR-T cell using anti body that targets an epitope close to the surface of tumor cells. My collaborator, Dr. Mitchell Ho, has identified a high affinity rabbit monoclonal antibody (YP218) specific for region III, which is located at the C-terminal end of mesothelin close to the tumor cell surface. We have tested the cytotoxicity of the hYP218 CAR-T construct on several mesothelin expressing cell lines and anti-tumor effect in animal models. The pre-clinical studies have shown increased tumor killing and efficacy in several pre-clinical tumor models such as ovarian and pancreatic cancer and in mesothelioma PDX models. We have further studied the efficacy of hYP218 CAR T cells in colorectal and gastric carcinoma pre-clinical models so that we can translate it to clinical trials of these malignancies. Alongside, we have been working on further improving the efficacy of CAR-T cell therapy by increasing persistence and tumor infiltration and reducing T cell exhaustion. We have shown that CAR T cells derived from naïve or stem cell memory T cells (TNhYP218 CAR T cells), have better persistence than bulk T cells in pre-clinical models. We have received FDA approval for the Phase 1 study of TNhYP218 CAR T cell therapy and have started recruiting subjects at NIH CC (ClinicalTrials.gov: NCT06885697). Additionally, we are studying the role of tumor microenvironment in CAR-T cell efficacy and persistence. Most studies done so far have been done in immunocompromised hosts that do not reflect the exact clinical set up. We have developed immunocompetent mice tumor models to accomplish these goals. Heterogeneity in tumor mesothelin expression and its shedding into the blood can hinder adoptive cell therapy. To overcome this, in collaboration with Eureka Therapeutics, we have developed antibody-T cell receptor (Ab-TCR) T cells targeting mesothelin intracellular peptides presented by MHC molecules. Ab-TCR consists of the antibody-derived Fab fragment fused to the gamma delta TCR , enabling TCR signaling upon target antigen recognition. Its activity is not limited by heterogenous tumor mesothelin expression or shed mesothelin in the blood and tumor. Moreover in vitro it has shown limited cytokine release. Immunopeptidomics was used to identify MSLN peptides presented by MHC molecules using mesothelioma and pancreatic cancer PDX tumors, and established cancer cell lines. The HLA class I binding peptides were purified and top antibody candidates against these peptides were selected using phage library screening. Based on sensitivity and binding affinity, two clones ET1508 targeting MSLN (539-547) VLPLTVAEV and ET2001 targeting MSLN (397-407) ALLEVNKGHEM were selected for Ab-TCR design. The lead candidate with increased in-vivo and in-vitro cell killing ability and increased persistence was selected for clinical development. The 1508-AbTCR T cell is now under clinical development. 2. Long term follow-up and early cancer detection in individuals with pathogenic germline BAP1 mutation. Our recent study of familial mesothelioma showed that 12% of unselected mesothelioma patients have pathogenic germline mutations in DNA repair genes, with BAP1 (BRCA1-associated protein) being most common. Since patients and their family members harboring germline BAP1 mutations are susceptible to other cancers such as cutaneous melanoma, uveal melanoma, meningioma, kidney, bladder, and breast cancer, early detection of these cancers could improve their outcome. We have therefore initiated a long-term prospective trial of cancer screening in these patients and their asymptomatic family members harboring pathogenic BAP1 mutations for early detection of different cancers to which they are predisposed. This protocol will provide definitive answers about incidence of different cancers in these families and whether early cancer detection will improve their outcomes. We are characterizing the natural and clinical history of malignant mesothelioma patients and their family members who have germline mutations in BAP1 gene. In addition, this protocol aims to provide ongoing surveillance for patients at increased risk for many common cancers. Genetic testing for DNA repair mutations is performed using a CLIA certified gene panel. If patients who have a diagnosis of mesothelioma are positive for a BAP1 pathogenic variant, they are eligible to enroll in the surveillance protocol (Cohort 1). In addition, family members (1st and 2nd degree relatives) of those patients that test positive for the familial pathogenic BAP1 variant are eligible for genetic testing. Any family members that test positive are also eligible to enroll in the surveillance protocol (cohort 2). Any individual who has a pathogenic variant in the BAP1 gene (unaffected by mesothelioma) is also eligible to participate in the study (Cohort 2). Since 2019, we have enrolled a total of 288 participants. During yearly screening, patients with new malignancies have been identified.