VO659 Earns Orphan Drug Designation

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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The U.S. Food and Drug Administration (FDA) has granted orphan drug designation to Vico Therapeutics’ VO659, an investigational antisense oligonucleotide gene-silencing therapy for Huntington’s disease.

“We are delighted that FDA has granted this orphan-drug designation,” Rupert Sandbrink, MD, PhD, chief medical officer of VICO, said in a press release. “This is affirmation of the potential of our AON [antisense oligonucleotide] approach.”

Huntington’s disease is caused by mutations in the huntingtin (HTT) gene, which expand the gene by introducing long segments of repeating CAG nucleotides. The expanded HTT gene provides the body’s cells with instructions to make a mutant huntingtin protein with an abnormally long tail made of multiple glutamine amino acids (one of the many protein building blocks). The mutant protein is toxic and leads to the symptoms associated with Huntington’s disease.

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Antisense oligonucleotides such as VO659 are artificially created nucleotides that bind to the HTT messenger RNA and prevent it from being translated into a protein. A messenger RNA is a molecule that serves as a template for cells to make the corresponding protein. In this way, the gene is “silenced” and the abnormally long huntingtin proteins are no longer produced.

According to the company, VO659 has the potential to slow or halt progression of Huntington’s disease as well as other diseases caused by mutant proteins with glutamine expansions.

“Huntington’s disease, like many types of SCA, belongs to the group of polyglutamine disorders which are rare genetic and progressive brain diseases,” Sandbrinck said. “Patients affected by Huntington’s disease experience motor disturbances, personality changes and dementia, leading to increasing disability, loss of independence and reduced survival. Only very limited, symptomatic treatment options are currently available for patients with this devastating disease,” he said. “Our investigational RNA modulating therapy is intended to be a disease-modifying treatment for polyglutamine disorders, designed to lower the mutant polyglutamine protein levels that cause these neurodegenerative diseases.”

VO659 previously received orphan drug designation for the treatment of spinocerebellar ataxia (SCA) by the FDA, and for the treatment of Huntington’s disease and SCA from the European Commission, based on positive reviews from the European Medicines Agency.