BTK and B-cell chronic lymphocytic leukemia: Hence, we analyzed changes in MDSC and T-cell subsets in CLL patients receiving this therapy, keeping in mind that the drug’s major target, BTK, is expressed by B cells and other cells (including MDSCs) [42–47], and that ibrutinib can inhibit other kinases in the TEC (e.g., ITK) and epidermal derived growth factor receptor families [48].