Sweden‑based Immedica secured accelerated approval from the FDA for a therapy addressing persistently elevated plasma arginine in ARG1‑D, a rare urea‑cycle disorder. The FDA’s action revives a once‑rejected program and establishes the first approved treatment targeting the primary metabolic driver of arginase deficiency. The approval follows submission materials and regulatory engagement that convinced FDA reviewers the drug meets criteria for accelerated approval in a small patient population. For rare‑disease developers, the decision highlights the potential to secure regulatory paths for targeted metabolic interventions when clinical endpoints and natural history support benefit.