A Case of Acute Motor and Sensory Axonal Neuropathy Secondary to SGN-LIV1A Therapy.

Antibody-drug conjugate therapy is rarely associated with neurologic immune-related phenomena. In this case report, we present a patient on treatment with SGN-LIV1A antibody-drug conjugate for breast cancer who developed progressive asymmetric quadriparesis, more severe in the bilateral upper extremities. Acute motor and sensory axonal neuropathy (AMSAN), a sub-variant of Guillain-Barré syndrome, was diagnosed via electro-diagnostic studies. Serological studies were significant for vitamin B1, B2 and B6 deficiencies, and cerebrospinal fluid studies were significant for albuminocytologic dissociation. The patient was treated with intravenous immunoglobulin (IVIg), B complex supplementation, and aggressive physical therapy. There was recovery of muscle strength in all extremities over the course of three months. Our case explores the biologic response to treatment of experimental immunotherapy-induced AMSAN with intravenous immunoglobulin.