Abstract
Introduction:
Adoptive cellular therapy with tumor-infiltrating lymphocytes (TIL) has demonstrated promising clinical benefits in several solid tumors, but the efficacy of this therapy might be compromised by the "prone-to-exhaustion" phenotype of TIL and poor persistence in vivo. This calls for a robust expansion process to produce a large number of cells for clinical usage while at the same time maintaining favorable anti-tumor function and memory phenotype. Previous studies showed that the PI3K-AKT signaling pathway plays a key role in the regulation of T cell activation, differentiation and memory formation.
Method:
We modulated the PI3K-AKT pathway in TIL isolated from cervical and ovarian cancer by application of AKT or PI3K inhibitors or CRISPR knockout of AKT1 and/or AKT2, and characterized their effects on TIL phenotype and effector function. Mechanistic study was further performed with RNA-seq analysis of AKT1/2 KO TIL in comparison to control TIL.
Result:
The inhibition of either PI3K or AKT led to an increase in the population of effector CD8+ T cells with upregulation of activation markers, elevated CD39- CD69- memory T cells, and significantly enhanced cytotoxicity when cocultured with tumor cell lines and patient-derived tumor samples. Moreover, dual knockout of AKT1 and AKT2 largely phenocopies the functional impact of AKT or PI3K inhibition on TIL. This result was further validated by RNA-seq analysis indicating that AKT1/2 ablation primarily regulates T cell differentiation and function-related programs.
Conclusion:
Modulation of PI3K-AKT signaling represents a promising strategy to enhance TIL stemness and cytotoxicity and improve the clinical outcome of current TIL-based therapy to treat solid tumors.