BTK and B-cell chronic lymphocytic leukemia: A transient increase in malignant cells in the circulation in patients with chronic lymphocytic leukemia (CLL) was observed after treatment with Bruton's tyrosine kinase (BTK) inhibitor ibrutinib or phosphoinositide 3‐kinase (PI3K) inhibitor idelalisib 24, 25, similar to the lymphocytosis in dasatinib‐treated patients.