Metabolic engineering against the arginine microenvironment enhances CAR-T cell proliferation and therapeutic activity

Abstract

Haematological and solid cancers catabolise the semi-essential amino acid arginine to drive cell proliferation. However, the resulting low arginine microenvironment also impairs chimeric antigen receptor T cells (CAR-T) cell proliferation, limiting their efficacy in clinical trials against haematological and solid malignancies. T cells are susceptible to the low arginine microenvironment due to the low expression of the arginine re-synthesis enzymes argininosuccinate synthase (ASS) and ornithine transcarbamylase (OTC). We demonstrate T cells can be re-engineered to express functional ASS or OTC enzymes, in concert with different chimeric antigen receptors. Enzyme modifications increase CAR-T cell proliferation, with no loss of CAR cytotoxicity or increased exhaustion. In vivo, enzyme-modified CAR-T cells lead to enhanced clearance of leukaemia or solid tumour burden, providing the first metabolic modification to enhance CAR-T cell therapies.

CAR T Cell Therapy for Solid Tumors: Bright Future or Dark Reality?

“…These include ex vivo loading of tumor-specific T cells with arginine, 228 or the genetic modification of CAR T cells with enzymes that are critical for arginine re-synthesis, including argininosuccinate synthase or ornithine transcarbamylase. 253 Investigators have also focused on manipulating glutamine metabolism in the TME, and recent studies have highlighted that glutamine antagonists and transient inhibition of glutaminase increase T cell effector function. 254,255 To protect CAR T cells from ROS, investigators have genetically modified T cells to secrete catalase.…”

Manipulating the Metabolism to Improve the Efficacy of CAR T-Cell Immunotherapy

“…Thus, CAR T-cells could be pre-incubated with specific metabolites such as L-arginine before their adoptive transfer to the patient. Another strategy, recently highlighted by the work of Fulthan et al [ 92 ], demonstrates that CAR T-cells are susceptible to low arginine level because of the low expression of the resynthesis enzymes, ornithine transcarbamylase and argininosuccinate synthase. Co-expressing these enzymes in a 4-1BB second-generation CAR showed a metabolic rewiring toward arginine and proline, as well as pyrimidine and purine metabolisms.…”

“…Co-expressing these enzymes in a 4-1BB second-generation CAR showed a metabolic rewiring toward arginine and proline, as well as pyrimidine and purine metabolisms. As a result, the proliferation of the modified CAR T-cells is enhanced in vitro and the antitumor efficacy is significantly improved for different in vivo pre-clinical tumor models [ 92 ].…”

The Great War of Today: Modifications of CAR-T Cells to Effectively Combat Malignancies

“…Decreased concentrations of arginine in serum and locally within the TME was reported in diverse types of malignancies and was shown to inhibit the expansion of both non-modified T cells and CAR-T cells [ 198 , 199 , 200 ]. The insertion of argininosuccinate synthase (ASS) and ornithine transcarbamylase (OTC) enzymes, responsible for arginine synthesis, increased CAR-T cell proliferation capacity, leading to enhanced anticancer efficacy against both haematological and solid tumours [ 201 ]. Indoleamine 2,3 dioxygenase (IDO), expressed by tumour and myeloid cells within the TME, is responsible for tryptophan conversion into metabolites that inhibit T cells.…”