SAR444245, a non‐alpha IL2, rescues chronic antigen and CAR‐driven T‐cell dysfunction

T cell dysfunction from chronic antigen stimulation limits the efficacy of T cell therapies. SAR444245 is a PEGylated, non-alpha IL2; PEG is attached to a novel amino acid such that it prevents binding to the alpha subunit of the IL-2 receptor, avoiding drug toxicities and expansion of regulatory T-cells, yet retains binding to the beta-gamma receptors that expand tumor-killing T cells. T-cell assays: CD8 T cells isolated from healthy donors were repetitively stimulated with antigen over 12 days to establish exhausted CD8 T cells. They were then exposed to SAR444245 for 7 days. Proliferation and co-inhibitory marker expression were measured as well as cytokine production by Luminex. CART cell assays: CD19 CAR T cells were generated from relapsed LBCL patient PBMCs obtained at the time of leukapheresis. Short term CAR T cell cytotoxicity was assessed by co-culture with 2 LBCL cell lines in the presence or absence of SAR444245 over 48 hours. Chronic CART stimulation was modelled in vitro by repeat addition of target tumor cells to CAR T cells every 48 hours over 8 days in the presence or absence of SAR444245. Live T cell and lymphoma cell counts as well as T-cell immunophenotyping were obtained at baseline and days 4 and 8. In vivo: Luciferase expressing Raji cells were injected into NSG mice. Tumor burden was monitored via BLI. Mice were either treated with anti-CD19/22 CAR T cells alone or in combination with SAR444245 (weekly treatment for 3 doses). Blood samples were obtained from mice on days 11 and 18 days post-CART infusion to immunophenotyping. Seven days following exposure to SAR444245, exhausted CD8 T cells demonstrated enhanced IFNγ and TNFα secretion, decreased co-inhibitory expression, and increased proliferation compared to cells not exposed to SAR444245. CD8 T cells exposed to SAR444245 on the day of initial activation, followed by repetitive antigen exposure, proliferated and maintained IFNγ similar to acutely stimulated CD8 T cells. Cytokine analysis of treated CD8 T cells demonstrated robust expression of cytokines and effector molecules, and increased polyfunctionality. In short term assays, SAR444245 induced T cell expansion without significant increase in cytotoxicity. However, in long-term assays mimicking chronic CAR stimulation and exhaustion, addition of SAR444245 to CAR T-cells resulted in enhanced CART-cell proliferation through day 8, and enhanced control of tumor cells. In an in vivo Raji model, the combination of SAR444245 with CD19/CD22 CART cells demonstrated enhanced CART expansion and sustained anti-tumor efficacy compared to CAR T cells alone. SAR444245 treatment of exhausted CD8 or CAR T cells restored functionality and alleviated T cell dysfunction. These data suggest that SAR444245 rescue of T cell exhaustion through maintenance of T cell proliferative capacity, cytotoxicity, and polyfunctionality and provide rationale for future clinical study of SAR444245. Encore Abstract - previously submitted to EHA 2023 The research was funded by: Sanofi Keywords: Aggressive B-cell non-Hodgkin lymphoma, Cellular therapies, Immunotherapy Conflicts of interests pertinent to the abstract. A. Choi Employment or leadership position: Sanofi R. Carrio Employment or leadership position: Sanofi N. Pate Employment or leadership position: Sanofi K. Malley Employment or leadership position: Sanofi D. Bangari Employment or leadership position: Sanofi J. Gavigan Employment or leadership position: Sanofi C. Shi Employment or leadership position: Sanofi B. Liu Employment or leadership position: Sanofi T. Byers Employment or leadership position: Sanofi I. Sassoon Employment or leadership position: Sanofi M. Cucchetti Employment or leadership position: Sanofi R. Wang Employment or leadership position: Sanofi M. Agarwal Employment or leadership position: Sanofi G. Abbadessa Employment or leadership position: Sanofi E. Meibalan Employment or leadership position: Sanofi L. Powers Employment or leadership position: Sanofi J. Cao Employment or leadership position: Sanofi X. Ying Employment or leadership position: Sanofi K. Balko Employment or leadership position: Sanofi Q. Yu Employment or leadership position: Sanofi J. Jiao Employment or leadership position: Sanofi V. Cortez-Retamozo Employment or leadership position: Sanofi S. Sidhu Employment or leadership position: Sanofi D. Shaffer Employment or leadership position: Sanofi X. Li Employment or leadership position: Sanofi M. R Green Research funding: Sanofi