GPRC5D Bispecific antibody talquetamab-induced dizziness-ataxia syndrome, clinical presentation and management- a case series

This is the authors' abstract. We don't add key points for this paper.

Talquetamab is the first FDA approved drug targeting G-protein-coupled receptor class 5 member D (GPRC5D) receptor with a high efficacy and durability of responses in heavily pretreated multiple myeloma (MM). Common side effects include Cytokine Release syndrome (CRS), Immune Effector Cell Associated Neurotoxicity Syndrome (ICANS), oral, skin and gastrointestinal toxicities are well documented. A lesser-known side effect of GPRC5D is a cerebellar toxicity which is independent of ICANS. This was first described with MCARH109 GPRC5D CART where 2 patients (3%) developed a Grade 3 cerebellar disorder [ 1 ]. As an extension of this syndrome dizziness can be the first presenting symptom of this neurological disorder. In a subsequent report of Arlo-cel (GPRC5D CART) notable symptoms include dizziness 9%, ataxia 7%, dysarthria 4%, cerebellar toxicity, paresthesia, gait disturbance, and nystagmus were present in 1% [ 2 ]. In the prescribing information of talquetamab with European Medical Agency [ https://www.ema.europa.eu/en/documents/product-information/talvey-epar-product-information_en.pdf ] based on MONUMENTAL-1 trial dizziness was present in 12% of patients and 8% had grade 3 dizziness. Herein, we report a case series documenting the clinical course of this dizziness-ataxia syndrome following talquetamab use.