Mesothelin antigen density influences anti-mesothelin chimeric antigen receptor T cell cytotoxicity

Gerard J Chu; Charles G Bailey; Rajini Nagarajah; Oliver Liang; Cynthia Metierre; Sharon M Sagnella; Laura Castelletti; Dannel Yeo; Stephen Adelstein; John E J Rasko

doi:10.1016/j.jcyt.2024.01.011

Mesothelin antigen density influences anti-mesothelin chimeric antigen receptor T cell cytotoxicity

Cytotherapy. 2024 Apr;26(4):325-333. doi: 10.1016/j.jcyt.2024.01.011. Epub 2024 Feb 13.

Authors

Affiliations

¹ Gene and Stem Cell Therapy Program Centenary Institute, Camperdown, NSW, Australia; Department of Clinical Immunology and Allergy, Royal Prince Alfred Hospital, Camperdown, NSW, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia. Electronic address: gerard.chu@health.nsw.gov.au.
² Gene and Stem Cell Therapy Program Centenary Institute, Camperdown, NSW, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia; Cancer and Gene Regulation Laboratory Centenary Institute, Camperdown, NSW, Australia. Electronic address: c.bailey@centenary.org.au.
³ Gene and Stem Cell Therapy Program Centenary Institute, Camperdown, NSW, Australia. Electronic address: r.nagarajah@centenary.org.au.
⁴ Gene and Stem Cell Therapy Program Centenary Institute, Camperdown, NSW, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia; Cell & Molecular Therapies, Royal Prince Alfred Hospital, Camperdown, NSW, Australia; Li Ka Shing Cell & Gene Therapy Program, University of Sydney, Camperdown, NSW, Australia. Electronic address: olia9830@uni.sydney.edu.au.
⁵ Gene and Stem Cell Therapy Program Centenary Institute, Camperdown, NSW, Australia. Electronic address: c.metierre@centenary.org.au.
⁶ Cell & Molecular Therapies, Royal Prince Alfred Hospital, Camperdown, NSW, Australia. Electronic address: sharon.sagnella@health.nsw.gov.au.
⁷ Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia; Cell & Molecular Therapies, Royal Prince Alfred Hospital, Camperdown, NSW, Australia; Li Ka Shing Cell & Gene Therapy Program, University of Sydney, Camperdown, NSW, Australia. Electronic address: laura.castelletti@health.nsw.gov.au.
⁸ Gene and Stem Cell Therapy Program Centenary Institute, Camperdown, NSW, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia; Cell & Molecular Therapies, Royal Prince Alfred Hospital, Camperdown, NSW, Australia; Li Ka Shing Cell & Gene Therapy Program, University of Sydney, Camperdown, NSW, Australia. Electronic address: dannel.yeo@sydney.edu.au.
⁹ Department of Clinical Immunology and Allergy, Royal Prince Alfred Hospital, Camperdown, NSW, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia. Electronic address: stephen.adelstein@sydney.edu.au.
¹⁰ Gene and Stem Cell Therapy Program Centenary Institute, Camperdown, NSW, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia; Cell & Molecular Therapies, Royal Prince Alfred Hospital, Camperdown, NSW, Australia; Li Ka Shing Cell & Gene Therapy Program, University of Sydney, Camperdown, NSW, Australia. Electronic address: j.rasko@centenary.org.au.

PMID: 38349311
DOI: 10.1016/j.jcyt.2024.01.011

Abstract

Background aims: Several anti-mesothelin (MSLN) chimeric antigen receptor (CAR) T cells are in phase 1/2 clinical trials to treat solid-organ malignancies. The effect of MSLN antigen density on MSLN CAR cytotoxicity against tumor cells has not been examined previously, nor are there data regarding the effect of agents that increase MSLN antigen density on anti-MSLN CAR T cell efficacy.

Methods: MSLN antigen density was measured on a panel of pancreatic cancer and mesothelioma cell lines by flow cytometry. In parallel, the cytotoxicity and specificity of two anti-MSLN CAR T cells (m912 and SS1) were compared against these cell lines using a real-time impedance-based assay. The effect of two MSLN 'sheddase' inhibitors (lanabecestat and TMI-1) that increase MSLN surface expression was also tested in combination with CAR T cells.

Results: SS1 CAR T cells were more cytotoxic compared with m912 CAR T cells against cell lines that expressed fewer than ∼170 000 MSLN molecules/cell. A comparison of the m912 and amatuximab (humanized SS1) antibodies identified that amatuximab could detect and bind to lower levels of MSLN on pancreatic cancer and mesothelioma cell lines, suggesting that superior antibody/scFv affinity was the reason for the SS1 CAR's superior cytotoxicity. The cytotoxicity of m912 CAR T cells was improved in the presence of sheddase inhibitors, which increased MSLN antigen density.

Conclusions: These data highlight the value of assessing CAR constructs against a panel of cells expressing varying degrees of target tumor antigen as occurs in human tumors. Furthermore, the problem of low antigen density may be overcome by concomitant administration of drugs that inhibit enzymatic shedding of MSLN.

Keywords: CAR; antigen density; chimeric antigen receptor T cells; mesothelin; mesothelioma; pancreatic cancer.

MeSH terms

Cell Line, Tumor
Humans
Immunotherapy, Adoptive
Mesothelin
Mesothelioma* / pathology
Mesothelioma* / therapy
Pancreatic Neoplasms* / therapy
Receptors, Chimeric Antigen* / metabolism
T-Lymphocytes / metabolism

Substances

Mesothelin
Receptors, Chimeric Antigen