Hsu, L.-Y.; Rosenbaum, J. T.; Lindner, S.; Allanore, Y.; Cauvet, A.; Pawar, R. D.; Li, D.; Van Den Brink, M.; Miller, R. A.

Interleukin-2-inducible T cell kinase (or ITK) is a tyrosine kinase predominantly expressed by T lymphocytes. It plays a major role in T cell activation, differentiation, and receptor signaling. Studies in mouse models have established that the absence or inhibition of ITK reduces the secretion of Th2 and Th17 cytokines, while favoring the production of Th1 cytokines and the differentiation of T cells to regulatory T cells (T regs). We recently characterized the activity of soquelitinib (SQL), a selective, covalent inhibitor of ITK in vitro using mouse or human T cells and in vivo in murine models of cancer. We hypothesized that selective pharmacologic blockade of ITK could attenuate a variety of T cell-mediated inflammatory diseases including murine models that resemble asthma, pulmonary fibrosis, systemic sclerosis, psoriasis, and acute graft versus host disease. In each model, SQL demonstrated substantial ability to ameliorate the disease process along with effects on cytokines and/or T cell subsets consistent with the reported function of ITK. Our studies demonstrate that selective inhibition of ITK by SQL is potentially a novel therapeutic approach for several forms of T cell-mediated, inflammatory diseases.