MM-368: Foot Drop in Patients Treated with Bortezomib- A Case Series and Review of the Literature

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Context Bortezomib-induced peripheral neuropathy (BIPN) has a profound impact on quality of life, which is an important issue considering the growing number of survivors in multiple myeloma (MM) and light-chain amyloidosis. BIPN is typically symmetric, distal, “stocking and glove” distribution and predominantly consists of sensory rather than motor symptoms. Motor neuropathy induced by bortezomib is uncommon and has been addressed specifically only in case reports and case series. No data has been published on foot drop in the context of bortezomib treatment. Objective Define the characteristics of foot drop associated with bortezomib treatment. Methods We identified the hospital records of 6 patients treated with bortezomib for MM or amyloidosis that developed foot drop, temporally related to bortezomib treatment. Results Six patients, 5 of whom are males, with a median age of 65 years (range 46–74), experienced foot drop. Patients were treated between 2010 and 2020. Three patients had MM, and 3 had AL amyloidosis. In four patients, the involved light chain was lambda, and in two, it was kappa. Two patients received the bortezomib intravenously, and 4 received it subcutaneously. Two patients received bortezomib at a twice-weekly schedule. Two patients did not have “classical” bortezomib peripheral neuropathy prior to the development of the foot drop. Two patients developed the foot drop in the first cycle, and 1 developed it 1 month after treatment discontinuation. One patient developed a foot drop that resolved after bortezomib was discontinued and recured when bortezomib was resumed. One patient had bilateral foot drop. Four patients reported complete resolution 1 year after treatment discontinuation, whereas two patients had gradual improvement but not complete resolution of their foot drop. Conclusions Clinicians need to be aware of the risk for “non-classical” rare neuropathies associated with bortezomib and should monitor for these toxicities and promptly discontinue bortezomib to prevent irreversible nerve damage. Other possible reasons for foot drop, such as compressions due to tumor infiltration or weight loss, should be considered.