Comprehensive Biomarker Strategy to Monitor GNTI-122, an Engineered Regulatory T Cell Therapy in Clinical Development to Treat Type 1 Diabetes 2252996

Abstract Introduction Engineered regulatory T cell (EngTreg) therapy offers a novel approach to restore immune tolerance in type 1 diabetes (T1D). To support POLARIS, GentiBio’s first-in-human trial of GNTI-122, we developed a biomarker program to monitor drug kinetics, pharmacodynamics, and immunogenicity. Methods Kinetics of GNTI-122 will be quantified by droplet digital PCR (ddPCR) detecting engineered transgenes. An 18-color flow cytometry panel is designed to detect GNTI-122, its Treg profile, and impact on immune subsets. Mechanism of action of GNTI-122 will be assessed by reduction in β cell-specific effector T cell (Teffs) responses using two complementary assays: an Activation-Induced Marker (AIM) assay and a FluoroSpot assay. Immunogenicity will be evaluated by a cell-based anti-drug antibody (ADA) assay targeting the TCR of GNTI-122. Results Biomarker assays demonstrated robust sensitivity, specificity and precision. Validated assays show the ability to detect GNTI-122 at a level of sensitivity < 0.1% of total WBCs. AIM and FluoroSpot assays reproducibly detected β cell-specific Teffs. Our cell-based anti-TCR ADA assay detected anti-TCR antibodies at a sensitivity < 850 ng/ml. Conclusion This comprehensive biomarker strategy provides a rigorous translational framework to monitor cellular kinetics, pharmacodynamics, and immunogenicity, to elucidate biological mechanisms of GNTI-122 for GentiBio’s POLARIS Phase 1 safety trial of GNTI-122 in recently diagnosed T1D. Funding Source T1D Fund Topic Categories Immune Mechanisms of Human Disease (HUM)