BOXR1030, an anti-GPC3 CAR with exogenous GOT2 expression, shows enhanced T cell metabolism and improved antitumor activity

PurposeThe solid tumor microenvironment (TME) drives T cell dysfunction and inhibits the effectiveness of immunotherapies such as chimeric antigen receptor-based T cell (CAR T) cells. Early data has shown that modulation of T cell metabolism can improve intratumoral T cell function in preclinical models. Experimental DesignWe evaluated GPC3 expression in human normal and tumor tissue specimens. We developed and evaluated BOXR1030, a novel CAR T therapeutic co-expressing glypican-3 (GPC3)-targeted CAR and exogenous glutamic-oxaloacetic transaminase 2 (GOT2) in terms of CAR T cell function both in vitro and in vivo. ResultsExpression of tumor antigen GPC3 was observed by immunohistochemical staining in tumor biopsies from hepatocellular carcinoma, liposarcoma, squamous lung cancer, and Merkel cell carcinoma patients. Compared to control GPC3 CAR alone, BOXR1030 (GPC3-targeted CAR T cell that co-expressed GOT2) demonstrated superior in vivo efficacy in aggressive solid tumor xenograft models, and showed favorable attributes in vitro including an enhanced cytokine production profile, a less-differentiated T cell phenotype with lower expression of stress and exhaustion markers, an enhanced metabolic profile and increased proliferation in TME-like conditions. ConclusionsTogether, these results demonstrated that co-expression of GOT2 can substantially improve the overall antitumor activity of CAR T cells by inducing broad changes in cellular function and phenotype. These data show that BOXR1030 is an attractive approach to targeting select solid tumors. To this end, BOXR1030 will be explored in the clinic to assess safety, dose-finding, and preliminary efficacy (NCT05120271). Statement of Translational RelevanceChimeric antigen receptor-based T cell (CAR T) therapeutics have revolutionized the field of oncology. Despite early successes targeting hematological malignancies, substantial challenges limit application of CAR T therapy in solid tumors, in part due to the suppressive tumor microenvironment which drives T cell exhaustion and metabolic dysfunction. Glutamic-oxaloacetic transaminase 2 (GOT2) is a mitochondrial enzyme in glutamine metabolism and contributes to cellular redox balance. Glypican-3 (GPC3) is an oncofetal tumor antigen with restricted expression on normal tissues and high prevalence in several solid tumors. We describe BOXR1030, a novel CAR T therapeutic co-expressing GPC3-targeted CAR and exogenous GOT2. Compared to T cells expressing CAR alone, BOXR1030 T cells demonstrated superior in vivo efficacy and have favorable attributes including enhanced cytokine production, a less-differentiated phenotype with lower expression of exhaustion markers, and an enhanced metabolic profile. These data support BOXR1030 as a potential treatment to explore in select solid tumor indications.