Dual inhibition of JAK3 and PD-L1 boosts immune response in triple negative breast cancer

Recent studies have shown that Janus Kinase inhibitors can enhance the tumor therapeutic effect of immune checkpoint inhibitors. However, it remains to be studied whether TYK2 selective inhibitors can enhance the therapeutic effect of small molecule PD-L1 inhibitors in triple-negative breast cancer (TNBC). We verified the efficacy of the combination of the selective TYK2 inhibitor Deucravacitinib and the small molecule inhibitor of PD-L1, INCB086550, in two TNBC animal models: a syngeneic mouse model (4T1 with humanized PD-L1) and a peripheral blood mononuclear cell (PBMC)-humanized model (MDA-MB-231). Following that, we explored the regulation of immune cell activity in tumors by the combined treatment using flow cytometry. Finally, we validated the expression of genes related to the regulated immune cells through reverse transcription-PCR. Both animal models demonstrated that the addition of a TYK2 inhibitor to a PD-L1 inhibitor significantly enhanced the antitumor capabilities of mice with good safety profiles. The combined therapy significantly elevated the counts of T, B, and natural killer cells while concurrently diminishing myeloid-derived suppressor cells in the syngeneic model. Similarly, in the PBMC-humanized model, this therapy markedly augmented progenitor-like and proliferative precursor-like CD8 T cells, while effectively diminishing exhausted and terminally differentiated CD8 T cell populations. This enhanced antitumor effect is associated with the modulation of antitumor immune-related gene expression by the combined therapy. The combination of TYK2 inhibitors and immune checkpoint inhibitors is a potentially effective strategy for treating TNBC.