A multi-kinase inhibitor screen identifies inhibitors preserving stem-cell-like chimeric antigen receptor T cells.

Chimeric antigen receptor T cells (CAR T cells) with T stem (T) cell-like phenotypic characteristics promote sustained antitumor effects. We performed an unbiased and automated high-throughput screen of a kinase-focused compound set to identify kinase inhibitors (KIs) that preserve human T cell-like CAR T cells. We identified three KIs, UNC10225387B, UNC10225263A and UNC10112761A, that combined in vitro increased the frequency of CD45RACCR7TCF1 T cell-like CAR T cells from both healthy donors and patients with cancer. KI-treated CAR T cells showed enhanced antitumor effects both in vitro and in vivo in mouse tumor models. The KI cocktail maintains T cell-like phenotype preferentially in CAR T cells originating from naive T cells and causes transcriptomic changes without arresting T cell activation or modulating the chromatin organization. Specific kinases, ITK, ADCK3, MAP3K4 and CDK13, targeted by the KI cocktail in a dose-dependent manner are directly associated with the preservation of T cell-like CAR T cells. Knockdown of these kinases individually or in combination enriches for T cell-like CAR T cells, but only CAR T cells generated in the presence of the KI cocktail show robust expansion and differentiation on stimulation with tumor cells. Overall, transient pharmacological inhibition of strategically targeted kinases maintains stem-like features in CAR T cells and improves their antitumor activity.