Beta-Hydroxybutyrate Content in Diet: A Potential Avenue for CAR T-Cell Efficacy Enhancement

According to a team of researchers, the β-hydroxybutyrate (BHB) content of diet, especially within a ketogenic diet, can amplify efficacy of chimeric antigen receptor (CAR) T-cell therapy. The team presented supporting findings at the 66^th American Society of Hematology Annual Meeting & Exposition in San Diego, California.

“The key mechanism involves the enhancement of the citric acid cycle and histone modifications during CAR T cell activation,” explained lead author Shan Liu, PhD, of the University of Pennsylvania, Philadelphia.

The team implanted diffuse large B-cell lymphoma (DLBCL) tumors into immunocompetent mice. The mice were then divided for feeding with either a nutrient content-matched control diet or one of five test diets: ketogenic diet or a diet with high cholesterol, fat, fiber, or protein content. All mice were infused with anti-CD19 CAR T cells and the researchers observed that the ketogenic diet group had more favorable overall survival and tumor control than the other diet groups, as well as markedly higher BHB levels.

Next, the team xenografted DLBCL tumors to immunodeficient NOD-SCID gamma chain-deficient mice and administered daily oral BHB gavage. They found that mice who received a suboptimal dose of anti-CD19 CAR T cells plus oral BHB had superior tumor control. They also found that the addition of BHB to xenografted mice’s drinking water increased the control of anti-mesothelin CAR T cells in pancreatic cancer tumors and of anti-CD19 CAR T cells in B cell acute lymphoblastic leukemia.

Further test results from the team underscore the role of BHB in CAR T cell function enhancement on carbon-13 isotope labeling. Antigen-activated CAR T cells also demonstrated a citric-acid-cycle-integration preference for BHB over standard glucose. Moreover, an assay for transposase-accessible chromatin with sequencing found that BHB treatment exposed key memory and effector genes in the CAR T cells.

Finally, the researchers performed retrospective mass spectrometry analysis of serum from 17 patients with LBCL from the NCT02030834 trial who had been infused with anti-CD19 CAR T cells and found a positive correlation between BHB serum concentration and cell expansion (P =.0164).

In addition, within the leukapheresis anti-CD19 products from two patients, they measured that cell proliferation absolute cell counts during ex vivo manufacturing approximately quadrupled after BHB was added to the cell culture media.

“The results of this study will be translated into a first-in-human clinical trial of BHB-supplementation during CART19 treatment for relapsed or refractory B cell lymphoma,” Dr. Liu mentioned.

Reference

Liu S, Guruprasad P, Han K, et al. Ketogenic diet enhances CAR T cell antitumor function via β-hydroxybutyrate. Abstract #4. Presented at the 66th American Society of Hematology Annual Meeting and Exposition; December 7-10, 2024; San Diego, California.