Abstract 4012: SOT302: Dual expression of exogenous glutamine oxaloacetate transaminase (GOT2) and TP53-induced glycolysis and apoptosis regulator (TIGAR) enhance CAR T cell activity in preclinical solid tumor models
Authors: Kuiper Emily , Bhaduri Samyabrata , Garafola Daniel , Sharma Kshitij , Coccia Jennifer , Whiteman Kathleen , Jensen-Smith Amy 
Published: March 2024

Background: Despite success in hematological malignancies, CAR T therapy has had limited efficacy against solid tumors. The suppressive tumor microenvironment limits CAR T activity through various mechanisms including competition for available nutrients and chronic stimulation resulting in reduced effector functions or T cell exhaustion. CAR T cells with enhanced metabolic fitness or more durable memory phenotype could potentially improve the clinical outcome in solid tumors. GOT2 plays an important role in mitochondrial function and maintenance of redox homeostasis. We have previously demonstrated enhancement of CAR T cells overexpressing GOT2. TIGAR is an enzyme known to promote antioxidative activites and reduce reactive oxygen species and has a role in protecting against apoptosis. Here we tested SOT302 CAR T cells expressing both GOT2 and TIGAR in preclinical solid tumor models.

Results: Expression of GOT2 and TIGAR transgenes were confirmed by qRT-PCR and western blot. Activity of GOT2 and TIGAR were confirmed by measuring aminotransferase activity (AST) and glutathione production, respectively. Compared to control CAR T cells, SOT302 is enriched for CD8+ Tscm cells and has a higher percentage functional, non-senescent (CD28+CD57-) cells. SOT302 has similar cytokine expression and cytotoxicity in standard co-culture assays compared to controls. SOT302 cells were chronically stimulated with plate-bound antigen every 3-4 days for 4 rounds. SOT302 had greater expansion of cells and were less exhausted and had better cytolytic capacity compared to controls. SOT302 cells were then evaluated in tumor xenograft mouse models. Consistent with our previous findings, CAR T cells expressing the single GOT2 transgene were more efficacious compared to CAR T cells alone. Expression of the single TIGAR transgene had no apparent benefit over CAR alone, however SOT302 cells expressing both GOT2 and TIGAR had superior anti-tumor activity compared to CAR alone and CAR+GOT2. No overt toxicity or significant body weight loss was observed. Ex vivo analyses to measure peripheral expansion, tumor infiltration and exhaustion were also performed. Preliminary findings indicate that SOT302 has better peripheral expansion compared to CAR alone and similar expansion compared to CAR+GOT2 controls. SOT302 cells had better tumor infiltration compared to both the CAR alone and CAR+GOT2 cells. Tumor infiltrating SOT302 cells also exhibited lower levels of exhaustion compared to CAR alone or CAR+GOT2 controls.

Summary: SOT302 cells express exogenous GOT2 and TIGAR transgenes and have superior anti-tumor activity in preclinical solid tumor models. These data suggest that SOT302 may be a promising candidate for patients with solid tumor cancers.

Citation Format: Emily Kuiper, Samyabrata Bhaduri, Daniel Garafola, Kshitij Sharma, Jennifer Coccia, Kathleen Whiteman, Amy Jensen-Smith. SOT302: Dual expression of exogenous glutamine oxaloacetate transaminase (GOT2) and TP53-induced glycolysis and apoptosis regulator (TIGAR) enhance CAR T cell activity in preclinical solid tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4012.