A phase 1 dose escalation study of a novel coupled CAR T cell therapy, GCC19CART, for patients with metastatic colorectal cancerBackground: GCC19CART, the first clinical candidate from the CoupledCAR solid tumor platform, is designed to overcome the limitations of conventional CAR T-cells in solid tumor malignancies by pairing solid tumor CAR T-cells with CD19-targeting CAR T-cells to amplify the proliferation and activation of the solid tumor CAR T component. GCC19CART targets guanylate cyclase-C (GCC), which is reported to be expressed in the metastatic lesions of 70%-80% of subjects with colorectal cancers and largely restricted to the intestinal tract. A Phase 1 investigator-initiated clinical trial conducted in China showed preliminary efficacy with an overall response rate (ORR) at dose level 1 (1x106 CAR T-cells/kg) of 15.4% ORR (2/13) and 50% ORR (4/8) in dose level 2 (2x106 CAR T-cells/kg). Common side effects included cytokine release syndrome (CRS) and diarrhea/colitis. Im
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