Enhanced STAT5a activation opposes Tox and rewires exhausted CD8 T cells towards a hybrid durable effector-like state during chronic stimulation [ATAC-Seq]

Here, we discovered a reciprocal antagonism between Stat5a and Tox in TEX cells. Stat5a antagonized the Tox-mediated exhaustion program to achieve a durable and protective hybrid effector/NK-like differentiation state in settings that typically drive exhaustion. Stat5 also drove TEX progenitors to differentiate into the effector-like TEXint subset, a key developmental step for PD-1 blockade responsiveness. Therapeutic enhancement of Stat5 activity in TEX cells using an orthogonal IL-2/IL2Rb pair system fostered TEXint cell accumulation and synergized with PD-L1 blockade. Finally, targeted delivery of Stat5-signals in TEX progenitors achieved partial epigenetic rewiring of these cells towards the effector/memory lineage and revived polyfunctionality. Together, these data highlight therapeutic opportunities of targeting Stat5 to antagonize the Tox-dependent epigenetic programming of TEX and provoke a hybrid program that exploits effector biology and durability for optimal therapeutic potential Three or more replicates from each sample were used for genomic DNA extraction and ATACseq assay was used to compare and analyse the open chromatin data to study the role of STAT5a in Tim3 postive CD8 subset cells