Mitigating T-Cell Mitochondrial Dysfunction in CLL to Augment CAR T-Cell Therapy: Evaluation in an Immunocompetent Model.

Abstract

An unmet clinical need in chronic lymphocytic leukemia (CLL) is emerging due to the rapidly expanding group of patients with double refractory (BTK- and Bcl2-inhibitor) disease. So far, autologous T-cell-based therapies, including chimeric antigen receptor (CAR) T-cells, have limited success in CLL, which has been attributed to an acquired CLL-mediated T-cell dysfunction and subset-skewing towards effector cells at the expense of memory formation. T-cell responses rely on dynamic metabolic processes, particularly mitochondrial fitness. While mitochondrial disruptions have been observed in solid tumor-infiltrating lymphocytes, their impact on T-cell immunity in lymphoproliferative disorders is unknown. Recent findings indicate that mitochondrial mass in CAR T-cells correlates with CLL clinical outcomes. This prompted an investigation into the mitochondrial fitness in CLL T-cells. Integrated metabolic and functional analyses revealed impaired, depolarized mitochondria across all T-cell subsets in untreated CLL patients, leading to further ex vivo and in vivo mouse studies on the underlying signaling alterations. Multi-omics profiling of transcriptome and epigenome revealed significant alterations in mitochondrial signaling, diminished AMP-activated protein kinase (AMPK) and autophagy activity, and upregulated glycolysis coupled with hyperactivation in the Akt kinase. Inhibition of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway during CLL T-cell culture induced metabolic reprogramming, enhancing mitochondrial activity, PPAR-gamma coactivator1α (PGC1α) expression, and memory differentiation. Underscoring clinical relevance, supplementation with the PI3kδ inhibitor idelalisib during CAR T-cell manufacturing improved persistence and long-term leukemia-free remissions in an immunocompetent murine model. Our study suggests that modulating the abnormal CLL T-cell metabolism can enhance the efficacy of autologous T-cell therapies.