Mecasermin Rinfabate

‍ Series A financing co-led by Balyasny Asset Management, venBio, and Janus Henderson Investors Rugonersen, a potentially best-in-class antisense oligonucleotide (ASO) therapy for Angelman syndrome, is expected to enter a Phase 3 clinical study in mid-2026 Doug Fambrough, Rich Gaster, and Sandeep Kulkarni join board of directors Cambridge (United States), June 1, 2026 - Oak Hill Bio, a clinical-stage rare disease therapeutics company, today announced the closing of a $32.5M Series A financing. The round was co-led by Balyasny Asset Management, venBio, and Janus Henderson Investors with participation from KCap Biotechnology Fund. Proceeds from the financing will be used to advance rugonersen, an investigational ASO therapy for the treatment of Angelman syndrome, into a pivotal Phase 3 clinical study. Angelman syndrome is a devastating neurodevelopmental disorder affecting approximately 30,000 diagnosed patients in the U.S. and EU5 with no approved treatments. Rugonersen was originally developed by Roche as a highly potent and specific therapy to restore UBE3A production in neurons. Several former members of the rugonersen program have joined Oak Hill Bio to lead development. “We are thrilled to welcome these exceptional investors and company-builders to our team. We really appreciate that they’ve recognized the strong science and data behind rugonersen and the tremendous need for a disease-modifying therapy in the Angelman syndrome community,” said Josh Distler, Chief Executive Officer of Oak Hill Bio. “With the financing and additions to our board, we are well-positioned to advance rugonersen into a Phase 3 study in the middle of 2026.” In connection with the financing, Oak Hill Bio made new appointments to the Board of Directors: Doug Fambrough: Dr. Fambrough is founder and portfolio manager of the KCap Biotechnology Fund and brings deep experience in RNA therapeutics, company creation, drug development, and business development. He was Founder, President, and Chief Executive Officer of Dicerna Pharmaceuticals, a pioneer in RNA interference-based medicines that was acquired by Novo Nordisk in 2021. Rich Gaster: Dr. Gaster is a Managing Partner at venBio, where he brings experience as a physician, entrepreneur, and life sciences investor. He has played a key role in launching and investing in more than a dozen venBio portfolio companies, including Akero Therapeutics, Harmony Biosciences, Ventyx Biosciences, Pharvaris, 35Pharma, Alumis, and others. Sandeep Kulkarni: Dr. Kulkarni brings more than two decades of experience across biotechnology, investment, entrepreneurship, and medicine. He is Co-Founder, Chief Executive Officer, and Director of Zura Bio, and previously served as Co-Founder and Chief Executive Officer of Tourmaline Bio, which was acquired by Novartis in a transaction completed in October 2025. “We are proud to support Oak Hill Bio in its mission to address a critical need in Angelman syndrome,” said Doug Fambrough, a member of the Board of Directors. “We were particularly impressed by rugonersen’s promising preclinical and Phase 1 data, which underscore rugonersen’s differentiation and potency. We believe rugonersen possesses best-in-class, disease-modifying potential and clearly demonstrates Oak Hill Bio’s ability to identify and acquire assets with significant therapeutic and commercial prospects.” ‍ About Oak Hill Bio Oak Hill Bio is a clinical-stage biotechnology company focused on acquiring and developing outstanding rare disease drugs that have been deprioritized by big pharma. The company's lead program is rugonersen (OHB-724), an investigational oligonucleotide entering Phase 3 that has best-in-class potential as a treatment for Angelman syndrome, a devastating neurodevelopmental disorder with no approved disease-modifying therapies. Oak Hill Bio is the trading name for OHB Pediatrics Ltd. It was formed in 2024 as a subsidiary of Oak Hill Bio Holdings (formerly known as Oak Hill Bio Ltd). Oak Hill Bio Holdings is developing OHB-607, a replacement therapy designed to prevent complications of prematurity in extremely preterm infants which is currently in a phase 2b study. For more information about Oak Hill Bio Holdings, please visit  www.oakhillbioholdings.com. ‍ About Angelman Syndrome Angelman syndrome (AS) is a serious rare genetic neurodevelopmental disorder which causes severe mental and physical impairment and affects approximately 15,000 patients in each of the US and the EU5, with an estimated incidence of 1 in 12,000 to 20,000 live births. AS is characterized by global developmental delay, intellectual disability, epilepsy (90% of cases before age 3 years) with an atypical underlying electroencephalogram (EEG), ataxia, tremor, hyperactivity, limited speech, and sleep dysregulation. Symptoms often emerge during infancy and persist throughout life. Deletions and mutations in the maternal ubiquitin protein ligase E3A (UBE3A) allele cause Angelman syndrome, due to epigenetic silencing of the paternal UBE3A allele by a long non-coding antisense RNA (UBE3A-ATS) in neurons. UBE3A is required for normal brain development and function. Failure to express ubiquitin E3A ligase in central nervous system (CNS) neurons leads to a build-up of damaged or unwanted proteins, that if left unchecked, can paralyze normal neuronal maturation, function, and synaptic pruning. ‍ About Rugonersen Rugonersen, an antisense oligonucleotide (ASO) designed to address the underlying disease biology of Angelman syndrome (AS) by specifically and potently binding the UBE3A-ATS transcript. Rugonersen binding triggers degradation of the UBE3A-ATS transcript in the CNS and therefore the unsilencing of the UBE3A paternal allele. Rugonersen allows neuronal expression of the paternal wild-type copy of the UBE3A gene, potentially restoring normal neuronal function and development in AS patients. Rugonersen’s clinical and preclinical data are detailed in the following publications: https://www.nature.com/articles/s41591-025-03784-7; Hipp, J.F., Bacino, C.A., Bird, L.M. et al. The UBE3A-ATS antisense oligonucleotide rugonersen in children with Angelman syndrome: a phase 1 trial. Nat Med (2025). https://doi.org/10.1038/s41591-025-03784-7; Jagasia et al., Angelman syndrome patient-derived neuron screen leads to clinical ASO rugonersen targeting UBE3A-ATS with long-lasting effect in monkeys, Nucleic Acids Research (2025). https://doi.org/10.1093/nar/gkaf851 ‍ Contacts Josh Distler, Chief Executive Officer josh.distler@oakhillbio.com Media media@oakhillbio.com ‍