RA Capital led a $175 million investment behind Oak Hill Bio, a startup developing an Angelman syndrome drug that Roche shelved and aiming to compete with late-stage programs from Ultragenyx and Ionis. The company is seeking a restart pathway for an experimental therapy that already has clinical comparators advancing in parallel. The competitive landscape is tight: Ultragenyx and Ionis are both running Phase 3 trials for similar approaches, with Ultragenyx expected to report results this year. Oak Hill’s thesis is that it can differentiate on molecule quality or development strategy while absorbing the risk of clinical and regulatory uncertainty. For the rare-disease sector, large-scale funding for a post-shelving asset signals continued investor appetite for probability-weighted “second lives” of clinically validated biology, particularly when multiple Phase 3 efforts are already under way. The next inflection point will be whether Oak Hill can generate data strong enough to justify differentiation against programs that are closer to readouts.