BTK inhibitor ibrutinib is cytotoxic to myeloma and potently enhances bortezomib and lenalidomide activities through NF-κB

► Bruton's tyrosine kinase inhibitors (such as ibrutinib) can be used in chemotherapy. ► BTK inhibitors are currently used in chronic lymphocytic leukaemia (CLL). ► Shown for the first time here, BTK inhibitors enhance multiple myeloma chemotherapies. ► BTK inhibitors act in MM cells via NF-κB inhibitory signalling pathways. ► BTK inhibitors would be useful clinically to treat multiple myeloma.