Most patients with chronic lymphocytic leukemia (CLL) relapse after first‐line chemoimmunotherapy and treatment with ibrutinib, an inhibitor of Bruton's tyrosine kinase (BTK), has improved prognosis of relapsed/refractory (R/R) patients in trials [1, 2] and real‐world reports. Here, BTK is linked to B-cell chronic lymphocytic leukemia.