Parkinsonian Patients Requiring Proteasome Inhibitors for Multiple Myeloma: Exceptional Circumstances Call for Extra Caution

Feedback on the management of patients with both Parkinson’s disease (PD) and multiple myeloma (MM) is not common in the literature, and we would like to report an original possible adverse event (AE) of MM chemotherapy: an increased PD severity induced by ixazomib. The patient, a 68-year-old man with PD (Hoehn and Yahr (HY) stage 3) was effectively and stably treated for 14 years with dopaminergic therapy (levodopa equiva25 lent daily dose (LEDD) 1275 mg). His symptomatic MM was first treated by lenalidomide (25 mg) with dexamethasone (Rd protocol) for 19 months. Then, a second-line therapy combined the proteasome inhibitor (PI) ixazomib (4 mg) with lenalidomide (20 mg) and dexamethasone (IRd protocol, 4-week cycle) due to MM progression