Cambridge, Massachusetts-based Oak Hill Bio, a clinical-stage rare disease company focused on repurposing deprioritized pharma assets, has closed a USD 32.5 million Series A financing round. Monies raised will primarily be used to advance its lead antisense oligonucleotide therapy, rugonersen, into a Phase III clinical study in Angelman syndrome.
The round was co-led by Balyasny Asset Management, venBio, and Janus Henderson Investors, with participation from KCap Biotechnology Fund. Oak Hill Bio said a pivotal Phase III study for the molecule will be initiated in mid-2026.
Rugonersen — originally developed by Roche before being acquired by Oak Hill Bio — is designed to address the root cause of Angelman syndrome by targeting the UBE3A antisense transcript (UBE3A-ATS) in neurons. By binding and triggering degradation of this transcript, the therapy aims to unsilence the paternal copy of the UBE3A gene, potentially restoring neuronal function in affected patients. Angelman syndrome, a severe neurodevelopmental disorder caused by loss of maternal UBE3A expression, affects an estimated 30,000 diagnosed patients across the US and EU5, with no approved disease-modifying treatments currently available.
Phase I trial results published in Nature Medicine documented the drug's tolerability and early efficacy signals in children with Angelman syndrome, while preclinical findings published in Nucleic Acids Research described durable effects in non-human primates.