SRRM2 is a target for the immunotherapy of AML with rationally designed CAR-T cells

Abstract

Abstract Background: Acute myeloid leukemia (AML) is a highly aggressive hematological malignancy that necessitates innovative treatment strategies to improve patient outcomes. The chimeric antigen receptor T cell immunotherapy (CAR-T) has emerged as a groundbreaking approach in immunotherapy; however, the lack of an optimal target antigen remains a significant impediment for CAR-T in its application to AML treatment. The nuclear speckle marker, serine/arginine repetitive matrix 2 (SRRM2), encompasses multiple disordered domains and its dysfunction is implicated in various human diseases. Methods: We tested the expression of SRRM2 antigen on peripheral blood cells and bone marrow cells AML patients. The clinical data of patients collected for studying the correlation between SRRM2 expression and clinical parameters. Then, a chimeric antigen receptor (CAR) containing a SRRM2-specific single-chain variable fragment, in combination with CD28, 4-1BB costimulatory domains, and CD3-ζ signaling domain was developed. LDH release assay was used to evaluate the in vitro cytotoxicity of the SRRM2 CAR-T cells. An AML mouse model of SKM-1 was established to evaluate the in vivo anti-leukemic activity of the SRRM2 CAR-T cells Results: In this study, we have observed the presence of SRRM2 expression on the cellular membrane. The membrane-expressed SRRM2 is elevated in AML patients and AML cell lines, particularly in individuals and cell lines harboring fms-like tyrosine kinase 3 (FLT3) gene mutations, making it an optimal target for CAR-T therapy. Then we designed and constructed a CAR, which targets SRRM2, involved the incorporation of SRRM2-specific single-chain variable fragments (ScFv), CD28 and 4-1BB costimulatory domains, as well as CD3-ζ signaling domains. The functionality of SRRM2 CAR-T cells was further investigated, revealing their specific cytotoxicity against SRRM2+ AML cell lines and enhanced potency against FLT3-mutant cells. In vivo SRRM2 CAR-T therapy of AML mice demonstrated the remarkable safety and efficacy profile. Conclusion: These results support that SRRM2 CAR-T represents a promising immunotherapy for the treatment of AML.