Whether the use of TKIs in GVHD results in improved GVL or lower relapse rates has not been elucidated, but could be anticipated given that tyrosine kinases, including Syk, Btk, and Itk, are key molecular targets in both, hematologic malignancies (32) and in alloreactive T-and B cells in GVHD (77). The gene discussed is BTK; the disease is graft versus host disease.