Repurposing With Purpose: Treatment of Bachmann-Bupp Syndrome With Eflornithine and Implications for Other Polyaminopathies.

Rare diseases impact approximately 1 in 10 people worldwide, and yet, less than 5% of all rare diseases currently have an approved treatment option available. This is due to many challenges unique to rare diseases, including small, diverse patient populations, the cost of drug development that is not proportionate to the number of patients who could potentially benefit from treatment, and difficulty with clinical trial design to validate new therapeutics. As a result, drug repurposing has become an increasingly promising option for finding treatment options for rare diseases. First described in 2018, Bachmann-Bupp Syndrome (BABS) is a rare neurodevelopmental disorder that is caused by gain-of-function variants in the ornithine decarboxylase (ODC1) gene and is characterized by developmental delay, hypotonia, and alopecia. Through collaboration and the use of a unique drug repurposing strategy, the first patient identified with BABS was treated with the repurposed drug eflornithine, also known as α-difluoromethylornithine (DFMO), in just 16 months. Currently, five additional patients with BABS are being treated with DFMO. This model of drug repurposing of an FDA-approved drug for use in another indication can serve as an example of what is possible in the scope of other rare diseases, specifically in other polyaminopathies.