Reversible Posterior Leukoencephalopathy Syndrome due to Carfilzomib

Carfilzomib is a proteasome inhibitor used in the treatment of relapsed and refractory plasma cell myeloma. We present here a case of Reversible Posterior Leukoencephalopathy Syndrome (RPLS) attributable to Carfilzomib, an adverse side effect that was not reported in studies prior to the approval of this drug for routine clinical use. The patient was a 67 year- old male with relapsed myeloma who received ten total doses of carfilzomib as part of CCyd, 8 of which were at a dose of 36 mg/m2. He subsequently developed a severe headache with neurological deficits that progressed to a profoundly depressed mental status and seizures. His radiologic findings, clinical course and subsequent recovery supported a diagnosis of RPLS. This follows the first reported case in early 2014 associated with carfilzomib, and follows several reported instances with the use of the earlier approved proteasome inhibitor bortezomib. Our observations may serve as a reference point for future examination of the dose-related toxicities of carfilzomib, both alone and in combination with other therapeutic agents in various therapy regimens. We believe this is an important consideration that should be brought to the attention of all physicians and researchers that use this drug.