Developing a membrane-proximal CD33-targeting CAR T cell

• Published in: Journal for immunotherapy of cancer Vol. 12; no. 5; p. e009013
• Main Authors: Freeman, Ruby, Shahid, Sanam, Khan, Abdul G, Mathew, Serena C, Souness, Sydney, Burns, Erin R, Um, Jasmine S, Tanaka, Kento, Cai, Winson, Yoo, Sarah, Dunbar, Andrew, Park, Young, McAvoy, Devin, Hosszu, Kinga K, Levine, Ross L, Boelens, Jaap Jan, Lorenz, Ivo C, Brentjens, Renier J, Daniyan, Anthony F
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group Ltd 20.05.2024; BMJ Publishing Group LTD; BMJ Publishing Group
• Series: Original research
• Subjects: Adoptive cell therapy - ACT; Amino acids; Animals; Antibodies; Antigens; Blood; Cell Line, Tumor; Chimeric antigen receptor - CAR; Flow cytometry; Humans; Immune Cell Therapies and Immune Cell Engineering; Immunoglobulins; Immunotherapy; Immunotherapy, Adoptive - methods; Leukemia; Leukemia, Myeloid, Acute - immunology; Leukemia, Myeloid, Acute - therapy; Lymphocytes; Mice; Penicillin; Proteins; Receptors, Chimeric Antigen - immunology; Receptors, Chimeric Antigen - metabolism; Sialic Acid Binding Ig-like Lectin 3 - immunology; Sialic Acid Binding Ig-like Lectin 3 - metabolism; Stem cell transplantation; T cell; T-Lymphocytes - immunology; Xenograft Model Antitumor Assays; New York; Atlanta Georgia; United States > US; Adoptive cell therapy - ACT; Immunotherapy; Leukemia; T cell; Chimeric antigen receptor - CAR
• ISSN: 2051-1426; 2051-1426
• DOI: 10.1136/jitc-2024-009013

BackgroundCD33 is a tractable target in acute myeloid leukemia (AML) for chimeric antigen receptor (CAR) T cell therapy, but clinical success is lacking.MethodsWe developed 3P14HLh28Z, a novel CD33-directed CD28/CD3Z-based CAR T cell derived from a high-affinity binder obtained through membrane-proximal fragment immunization in humanized mice.ResultsWe found that immunization exclusively with the membrane-proximal domain of CD33 is necessary for identification of membrane-proximal binders in humanized mice. Compared with clinically validated lintuzumab-based CAR T cells targeting distal CD33 epitopes, 3P14HLh28Z showed enhanced in vitro functionality as well as superior tumor control and increased overall survival in both low antigen density and clinically relevant patient-derived xenograft models. Increased activation and enhanced polyfunctionality led to enhanced efficacy.ConclusionsShowing for the first time that a membrane-proximal CAR is superior to a membrane-distal one in the setting of CD33 targeting, our results demonstrate the rationale for targeting membrane-proximal epitopes with high-affinity binders. We also demonstrate the importance of optimizing CAR T cells for functionality in settings of both low antigen density and clinically relevant patient-derived models.