Itraconazole and Lacosamide Combination Therapy Rescues CGG Repeat Expansion Induced Neurotoxicity in Fragile X-Associated Tremor/Ataxia Syndrome.

Carriers of the fragile X messenger ribonucleoprotein 1 (FMR1) gene have an elevated risk of developing Fragile X-associated tremor/ataxia syndrome (FXTAS), a progressive late-onset neurodegenerative disorder. Expansion of CGG trinucleotide repeats within the 5' untranslated region leads to RNA-mediated toxicity and promotes the aggregation of toxic FMR1polyglycine (FMR1polyG), driving neuronal dysfunction and degeneration. Yet, effective therapies that alter disease progression remain lacking. In this study, we evaluated a drug repurposing strategy to modulate FXTAS pathogenesis by targeting CGG repeat RNA structures using Itraconazole (ITZ), a clinically approved antifungal, in combination with Lacosamide (LCM), an established antiepileptic drug. The ITZ+LCM combination significantly reduced FMR1polyG aggregation and attenuated oxidative stress and cell death in an in vivoDrosophila model of FXTAS. Notably, this combination also improved locomotor performance and extended the lifespan of model flies, with a fourfold reduction in the effective ITZ dose. These findings were further validated at the cellular level using (CGG)99 transfected HEK293T and COS-7 cells, wherein the ITZ+LCM treatment suppressed FMR1polyG aggregation and corrected CGG repeat splicing defects. Biophysical studies revealed the selective interaction of the drug combination with CGG-expanded RNA. These findings identify the ITZ+LCM combination as a promising, clinically translatable therapeutic strategy against FXTAS to counter RNA-mediated neurotoxicity.