Oak Hill Bio Goes Public via RA Capital SPAC: $175M for Angelman Syndrome ASO Therapy

Oak Hill Bio, a clinical-stage rare disease company, announced a business combination with Research Alliance Corporation III (RACC), a SPAC sponsored by RA Capital Management, on July 27. The deal is expected to provide approximately $175 million in gross proceeds: $75 million from RACC’s trust account, fully backstopped by RA Capital, plus $100 million in committed private financing. The combined entity will trade on Nasdaq under the ticker OAKH, with deal close expected by end of 2026.

Oak Hill Bio’s lead asset is rugonersen, an antisense oligonucleotide (ASO) therapy advancing toward Phase 3 for Angelman syndrome. The drug was originally developed by Roche as RO7248828 and tested in the Phase 1 TANGELO trial. Oak Hill Bio licensed global rights from Roche, and the Phase 1 data was published in Nature Medicine, showing evidence of improvement in brain activity and developmental ability in children with the disorder.

Angelman syndrome is a rare neurogenetic disorder caused by loss of function in the UBE3A gene on chromosome 15. It is characterized by severe intellectual disability, impaired communication, motor impairment, and debilitating seizures. There are no FDA-approved treatments for Angelman syndrome.

Rugonersen is not the only ASO targeting Angelman. Ionis Pharmaceuticals (IONS) has ION582, which received FDA Breakthrough Therapy designation and is in the Phase 3 REVEAL study with enrollment on track to complete in 2026. Ultragenyx (RARE) has GTX-102 (apazunersen), also an ASO, which received Breakthrough Therapy designation and has fully enrolled its Phase 3 Aspire study with approximately 129 participants ages 4 to 17. Results are expected in the second half of 2026. MavriX Bio has FDA clearance for a first-in-human gene therapy trial.

Oak Hill Bio enters this competitive field as the third ASO in development, behind Ionis and Ultragenyx in trial enrollment. But rugonersen’s Phase 1 TANGELO data and its designation as a potential best-in-class treatment by Oak Hill Bio suggest the company sees differentiation in the molecule. The $175 million raise gives Oak Hill runway to initiate its Phase 3 program, though the company will likely need additional capital to complete a registrational trial.

The SPAC route to public markets is notable in a biotech IPO market that has been gradually reopening. Scribe Therapeutics priced a $128.7 million IPO earlier in 2026, backed by Lilly and Sanofi. Oak Hill Bio’s $175 million raise via RA Capital’s SPAC exceeds that, and RA Capital’s dual role as both SPAC sponsor and trust backstopper signals strong institutional conviction in the asset. The SPAC structure provides deal certainty that a traditional IPO cannot guarantee in a still-selective market.

The risk is clear: Oak Hill Bio is entering a crowded Angelman pipeline where two competitors are already in Phase 3 with fully enrolled trials. Ultragenyx expects Aspire data in H2 2026, and Ionis is on track to complete REVEAL enrollment this year. If either competitor reports positive Phase 3 data first, rugonersen’s market opportunity could narrow significantly before Oak Hill’s program reaches the same stage. RA Capital’s backing is a strong signal, but the company’s value hinges on Phase 3 execution in a race where it starts behind.

What to watch next: the SPAC deal close expected by end of 2026, when OAKH begins trading. The more immediate catalyst is whether Ultragenyx’s GTX-102 Aspire data lands in H2 2026, which would set the competitive bar for all Angelman programs.