MicroRNA-mediated metabolic reprogramming of chimeric antigen receptor T cells

Advances made in chimeric antigen receptor (CAR) T cell therapy have revolutionized the treatment and management of certain cancers. Currently, B cell malignancies have been among the few cancers to which CAR T cells have shown persistent and resilient anti-tumor responses. A growing body of evidence suggests that the persistence of CAR T cells within patients following infusion is linked to the mitochondrial fitness of the CAR T cell, which could affect clinical outcomes. Analysis of CAR T cells from patients undergoing successful treatment has shown an increase in mitochondrial mass and fusion events, and a reduction in aerobic metabolism, highlighting the importance of mitochondria in CAR T cell function. Consequently, there has been recent interest and investment in approaches that focus on mitochondrial programming. In this regard, miRNAs are promising agents in mitochondrial reprogramming for several reasons: (1) natural and artificial miRNAs are non-immunogenic, (2) one miRNA can simultaneously modulate the expression of multiple genes within a pathway, (3) the small size of a sequence required for producing mature miRNA is ideal for use in viral vectors and (4) different precursor miRNAs (pre-miRNAs) hairpins can be incorporated into a polycistronic miRNA cluster to create a miRNA cocktail. In this perspective, we describe the latest genetic engineering strategies that can be used to achieve the optimal expression of candidate miRNAs alongside a CAR construct. In addition, we include an in silico analysis of rational candidate miRNAs that could promote the mitochondrial fitness of CAR T cells.