BTK and B-cell chronic lymphocytic leukemia: Novel immunotherapeutics with B-cell receptor signaling inhibitors used against Bruton tyrosine kinase (BTK), such as ibrutinib, acalabrutinib, and zanubrutinib, are rapidly being included in the clinical paradigm of patients with either untreated or relapsed/refractory CLL and SLL [15,16,17,18].