Ibrutinib-induced polyneuropathy: A case report.

Introduction: Ibrutinib is an oral irreversible inhibitor of Bruton's tyrosine kinase signaling. It is a well-tolerated agent with some side-effects, the most common of which are atrial fibrillation, diarrhea, upper respiratory tract infection, fatigue, nausea, rash and cytopenias. Most of these toxicities are mild, although some have a severe clinical course.

Case Report: The case is here reported of a chronic lymphocytic leukemia patient with ibrutinib-induced polyneuropathy. A 63-year-old male patient with chronic lymphocytic leukemia was given ibrutinib as a third line treatment regimen. After the 10th month of therapy he had progressive complaints of numbness and tingling in his legs. The patient was diagnosed as grade 3 sensorineural polyneuropathy with electromyography. Considering that ibrutinib treatment may cause neuropathy, the ibrutinib was discontinued, after which the neuropathic complaints improved. However, the neck and axillary lymph nodes were enlarged and treatment had to be re-started therefore ibrutinib was started at a low dose and gradually increased. The patient is currently in the 14th month of treatment and still using ibrutinib without any severe side-effects.

Discussion: To the best of our knowledge, polyneuropathy as a unique side-effect of ibrutinib has not been previously reported. In addition to the well-known side effects of ibrutinib treatment, it should be kept in mind that polyneuropathy may also develop.