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Chemistry: Generation 2+ 

ION260, also known as BIIB132, is an investigational antisense medicine targeting ataxin-3 (ATXN3) messenger ribonucleic acid (mRNA). ION260 is designed to reduce the production of ATXN3 protein. Patients with a trinucleotide repeat expansion in the ATXN3 gene develop Spinocerebellar Ataxia Type 3 (SCA3).  Preclinical studies have shown that lowering of ATXN3 protein is associated with decreased progression of SCA3-like disease1.

About Spinocerebellar Ataxia Type 3

Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease, is a rare, inherited form of ataxia.  SCA3 is the most common dominant ataxia, and though prevalence estimates have not been systematically collected, there is likely between 20,000-40,000 patients in major markets2. Signs and symptoms typically begin in mid-adulthood, though can arise throughout life. SCA3 is characterized by progressive movement dysfunction. People with this condition initially experience problems with gait, coordination, and balance (ataxia). Other symptoms of SCA3 include speech difficulties (dysarthria), uncontrolled muscle tensing (dystonia), muscle stiffness (spasticity), involuntary eye movements (nystagmus) and tremors.   Symptoms progress in SCA3 patients to require wheelchair assistance, and SCA3 is ultimately fatal with patients usually surviving 10 to 20 years after symptom onset.