Work

CD22 CAR linker, hinge, and transmembrane domains affect ligand-dependent protein interactions and in-human performance

Year: 2026

Type: article

Abstract: ABSTRACT CD19-directed chimeric antigen receptor (CAR) therapy has led to robust remission rates in B cell Acute Lymphoblastic Leukemia (ALL), but CD19-negative relapses necessitate targeting alternative antigens. We initiated a phase 1 clinical trial of a CAR targeting CD22 (CAR22v1), but no appreciable in vivo expansion or antileukemic efficacy was observed (NCT03244306). A second construct, CAR22v2, was developed with alternate hinge, transmembrane, and scFv linker domains. The CAR22v2 phase 1 portion of the trial (NCT04571138) demonstrated enhanced in vivo expansion and improved antileukemic activity. We ran a series of extended assays to identify differences that might have predicted the different in-human response, which led to identification of minor differences, but nothing predictive of the clinical CAR22v1 failure. However, analysis of protein interaction networks revealed widespread differences in signaling complex assembly, with CAR22v1 and CAR22v2, exhibiting substantially different resting-state interaction profiles. Together, these data show that clinically meaningful differences in CAR function are accompanied by broad changes in signaling network organization.

Source: Blood Immunology & Cellular Therapy

DOI: 10.1016/j.bict.2026.100079