CD37 and B-cell chronic lymphocytic leukemia: As reduction of circulating B cells and other blood cells expressing CD37 (e.g. T cells) underpins the mechanism of action of BI 826826 in both CLL and NHL, differences in clearance rate probably reflect the differences in the expression profile of CD37 in the two diseases, with higher expression in blood, spleen and bone marrow of patients with CLL compared to NHL.