JAK1 and graft versus host disease: Indeed, drugs as itacitinib, a highly selective JAK1 inhibitor, initially developed for the treatment of different malignancies, has been and is currently being tested in different clinical trials for GVHD, as well as bariticinib, which blocks JAK1 and 2—another very promising JAK inhibitor, considering the data obtained in a preclinical murine model [25].