Richardson PG, et al. - Ibrutinib is a first-in-class, once-daily, oral covalent inhibitor of Bruton tyrosine kinase, which is overexpressed in the myeloma stem cell population. In this current study, various doses of ibrutinib ± low-dose dexamethasone were exanubed in patients who received ≥2 prior lines of therapy, including an immunomodulatory agent. Ibrutinib showed favourable safety and tolerability profile with encouraging efficacy.