Metabolic reprogramming via an engineered PGC-1α improves human chimeric antigen receptor T-cell therapy against solid tumors

BackgroundCellular immunotherapies for cancer represent a means by which a patient's immune system can be augmented with high numbers of tumor-specific T cells. Chimeric antigen receptor (CAR) therapy involves genetic engineering to 'redirect' peripheral T cells to tumor targets, showing remarkable potency in blood cancers. However, due to several resistance mechanisms, CAR-T cell therapies remain ineffective in solid tumors. We and others have shown the tumor microenvironment harbors a distinct metabolic landscape that produces a barrier to immune cell function. Further, altered differentiation of T cells within tumors induces defects in mitochondrial biogenesis, resulting in severe cell-intrinsic metabolic deficiencies. While we and others have shown murine T cell receptor (TCR)-transgenic cells can be improved through enhanced mitochondrial biogenesis, we sought to determine whether human CAR-T cells could be enabled through a metabolic reprogramming approach.Materials and methodsAnti-EGFR CAR-T cells were infused in NSG mice which bore A549 tumors. The tumor infiltrating lymphocytes were analyzed for exhaustion and metabolic deficiencies. Lentiviruses carrying PPAR-gamma coactivator 1 alpha (PGC-1 alpha), PGC-1 alpha(S571A) and NT-PGC-1 alpha constructs were used to co-transduce T cells with anti-EGFR CAR lentiviruses. We performed metabolic analysis via flow cytometry and Seahorse analysis in vitro as well as RNA sequencing. Finally, we treated therapeutically A549-carrying NSG mice with either PGC-1 alpha or NT-PGC-1 alpha anti-EGFR CAR-T cells. We also analyzed the differences in the tumor-infiltrating CAR-T cells when PGC-1 alpha is co-expressed.ResultsHere, in this study, we show that an inhibition resistant, engineered version of PGC-1 alpha, can metabolically reprogram human CAR-T cells. Transcriptomic profiling of PGC-1 alpha-transduced CAR-T cells showed this approach effectively induced mitochondrial biogenesis, but also upregulated programs associated with effector functions. Treatment of immunodeficient animals bearing human solid tumors with these cells resulted in substantially improved in vivo efficacy. In contrast, a truncated version of PGC-1 alpha, NT-PGC-1 alpha, did not improve the in vivo outcomes.ConclusionsOur data further support a role for metabolic reprogramming in immunomodulatory treatments and highlight the utility of genes like PGC-1 alpha as attractive candidates to include in cargo along with chimeric receptors or TCRs for cell therapy of solid tumors.

Automated summary

This study demonstrates that an engineered version of the inhibitory transcription factor PGC-1 alpha can metabolically reprogram human CAR-T cells, resulting in improved in vivo efficacy for the treatment of solid tumors. In contrast, a truncated version of PGC-1 alpha, NT-PGC-1 alpha, did not improve the in vivo outcomes.