Rugonersen

Brain cells normally use only the mother's copy of the UBE3A gene, because a long RNA strand called the UBE3A antisense transcript keeps the father's copy switched off. In Angelman syndrome the mother's copy is missing or does not work, so brain cells make too little UBE3A protein ^{[9] [7]}. Rugonersen is a short, chemically modified strand of genetic material designed to lower that antisense transcript so the father's copy can make UBE3A ^[8].

Oak Hill says rugonersen and Ultragenyx's apazunersen are distinct molecules, with different sequences, chemistry and targets within the antisense transcript, and that this does not mean rugonersen will work ^[3].

BEACON (NCT07605429) is a randomized, double-blind Phase 3 trial, meaning neither families nor doctors know who gets the drug, in up to 165 people aged 1 to 50, comparing rugonersen with a sham procedure that mimics the injection without giving the drug.

It enrolls people whose Angelman syndrome comes from a missing piece of the mother's chromosome 15 that includes UBE3A or from a change in the mother's UBE3A gene; people with paternal uniparental disomy, where both copies of chromosome 15 came from the father, or an imprinting defect, where the mother's copy is present but switched off, are excluded.

It also excludes anyone who has been in a cell therapy, gene therapy, gene editing or antisense medicine trial, people who used blood thinners or antiplatelet medicines, which stop blood from clotting, in the 2 weeks before screening, and children weighing 7.5kg or less. Its main measure is the change in thinking skills or the ability to communicate on the Bayley-4, a standard test of child development, at week 56.

ClinicalTrials.gov lists 7 US sites as recruiting: Cedars-Sinai, Rady Children's in San Diego, Children's Hospital Colorado, Nicklaus Children's in Miami, Rush University, UNC Chapel Hill and Vanderbilt ^[10]. Oak Hill expects first results in early 2029, and everyone who finishes 56 weeks can join a 2-year extension ^[1].

In Roche's open-label Phase 1 TANGELO study (NCT04428281), published in Nature Medicine in 2025, everyone knew they were getting the drug. A brain wave measure linked to Angelman syndrome moved partway toward normal, more at higher doses, and children's gains on most development measures, 4 of 5 Bayley areas and all 5 Vineland areas, were above what records of untreated children with Angelman predict, with no link to dose.

The study had no placebo group, and the authors wrote that the efficacy signals must be interpreted with caution ^[7]. The authors wrote that dosing every 12 weeks, the BEACON schedule, is expected to give a stronger lasting effect on the brain wave measure than the schedules tested and may bring greater clinical improvement ^[7]. Oak Hill runs an expanded access program (NCT07136454) that continues rugonersen only for children who took part in the TANGELO extension ^[11].

In Roche's Phase 1 TANGELO study, 61 children aged 1 to 12 received 450 spinal injections in all, some of them in the study for up to 4 years. No child left the study because of side effects, although 28 children left after Roche stopped development and did not return.

The most common side effects were fever in 52 of 61 children (85%), usually a few days after a dose and lasting 2 to 5 days, more often and for longer at higher doses, and severe in 12 (20%); vomiting (67%); worse unsteadiness or balance problems (41%), most often more of the unsteadiness children already had; seizures (31%); and raised spinal fluid pressure and headache (26% each).

Serious side effects occurred in 21 children (34%), and investigators judged them related to the drug in 8 (13%), including seizures, epilepsy, vomiting, fever, headache after the spinal tap, irritability and raised spinal fluid pressure. One child had a fever above 40°C after a 180mg dose that investigators counted as dose-limiting; it led to a hospital stay and had resolved by discharge 13 days after the dose ^[7].

Of 13 children without epilepsy at the start, 9 developed it during the study, which the authors said matched what records of untreated children with Angelman predict ^[7]. Oak Hill has not reported a clinical hold.

Roche developed rugonersen and ran the TANGELO study from 2020. On June 20, 2023 Roche said it would stop its own clinical development and seek an outside partner, and it set an end date for the study; in April 2024 it said children could keep receiving rugonersen in an open-label extension ^[7]. Oak Hill Bio announced an exclusive global license from Roche on April 15, 2025 ^[4]; it is the trading name of OHB Pediatrics, the BEACON sponsor ^{[1] [10]}.

After Ultragenyx reported on September 2, 2026 that its Angelman antisense drug apazunersen missed its main goal in the Phase 3 Aspire study ^[2], Oak Hill wrote to the Angelman community on September 9 that it does not believe that result predicts rugonersen's, and that it cannot know in advance how any trial will turn out ^[3]. In July 2026 Oak Hill agreed to combine with Research Alliance Corporation III to become a public company, a deal expected to close by the end of 2026 ^{[5] [6]}. Oak Hill and Roche have not announced any FDA designations.