Discovery and preclinical development of a therapeutically active nanobody-based chimeric antigen receptor targeting human CD22

• Published in: Molecular Therapy: Oncology Vol. 32; no. 1; p. 200775
• Main Authors: McComb, Scott, Arbabi-Ghahroudi, Mehdi, Hay, Kevin A., Keller, Brian A., Faulkes, Sharlene, Rutherford, Michael, Nguyen, Tina, Shepherd, Alex, Wu, Cunle, Marcil, Anne, Aubry, Annie, Hussack, Greg, Pinto, Devanand M., Ryan, Shannon, Raphael, Shalini, van Faassen, Henk, Zafer, Ahmed, Zhu, Qin, Maclean, Susanne, Chattopadhyay, Anindita, Gurnani, Komal, Gilbert, Rénald, Gadoury, Christine, Iqbal, Umar, Fatehi, Dorothy, Jezierski, Anna, Huang, Jez, Pon, Robert A., Sigrist, Mhairi, Holt, Robert A., Nelson, Brad H., Atkins, Harold, Kekre, Natasha, Yung, Eric, Webb, John, Nielsen, Julie S., Weeratna, Risini D.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 21.03.2024; Cell Press; American Society of Gene & Cell Therapy; Elsevier
• Subjects: CAR optimization; CAR-T; CD22; cell therapy; chimeric antigen receptors; hematological malignancy; leukemia and lymphoma; MT: Regular Issue; nanobody; Original; preclinical development; single-domain antibody; leukemia and lymphoma; CAR-T; cell therapy; chimeric antigen receptors; MT: Regular Issue; nanobody; hematological malignancy; CD22; single-domain antibody; preclinical development; CAR optimization
• ISSN: 2950-3299; 2950-3299
• DOI: 10.1016/j.omton.2024.200775

Chimeric antigen receptor (CAR) T cell therapies targeting B cell-restricted antigens CD19, CD20, or CD22 can produce potent clinical responses for some B cell malignancies, but relapse remains common. Camelid single-domain antibodies (sdAbs or nanobodies) are smaller, simpler, and easier to recombine than single-chain variable fragments (scFvs) used in most CARs, but fewer sdAb-CARs have been reported. Thus, we sought to identify a therapeutically active sdAb-CAR targeting human CD22. Immunization of an adult Llama glama with CD22 protein, sdAb-cDNA library construction, and phage panning yielded >20 sdAbs with diverse epitope and binding properties. Expressing CD22-sdAb-CAR in Jurkat cells drove varying CD22-specific reactivity not correlated with antibody affinity. Changing CD28- to CD8-transmembrane design increased CAR persistence and expression in vitro. CD22-sdAb-CAR candidates showed similar CD22-dependent CAR-T expansion in vitro, although only membrane-proximal epitope targeting CD22-sdAb-CARs activated direct cytolytic killing and extended survival in a lymphoma xenograft model. Based on enhanced survival in blinded xenograft studies, a lead CD22sdCAR-T was selected, achieving comparable complete responses to a benchmark short linker m971-scFv CAR-T in high-dose experiments. Finally, immunohistochemistry and flow cytometry confirm tissue and cellular-level specificity of the lead CD22-sdAb. This presents a complete report on preclinical development of a novel CD22sdCAR therapeutic. [Display omitted] McComb and colleagues report on their work to develop a camelid-nanobody-based chimeric antigen receptor-T cell therapy targeting human CD22 antigen. A membrane-proximal domain targeting CD22 nanobody CAR incorporating a CD8-transmembrane domain was selected as lead based on superior in vitro cytotoxicity, specificity, persistence, and in vivo activity.