The FDA granted accelerated approval to Immedica Pharma’s pegzilarginase (Loargys) for treating arginase 1 deficiency (ARG1‑D) in patients aged two and older, reversing an earlier regulatory refusal and delivering the first approved therapy for this ultra‑rare urea cycle disorder. The accelerated approval follows additional data and regulatory engagement that addressed prior agency concerns. Immedica’s Loargys replaces a previously unmet standard of care for a condition affecting roughly 250 U.S. residents, promising to reduce plasma arginine and mitigate neurologic sequelae. The decision restores a program that had faced a prior refusal to file and highlights the FDA’s willingness to reconsider earlier verdicts when companies supply supplemental evidence or new analyses. The approval will affect treatment access for a very small patient population and underscores how regulators and sponsors can resolve earlier review deficiencies to bring enzyme replacement and substrate‑lowering therapies to market under accelerated pathways.