FDA

FDA grants accelerated approval to Loargys for arginase I deficiency

February 26, 2026

Brand name: Loargys

Generic name: pegzilarginase-nbln

Manufacturer: Immedica Pharma

Approval date: February 23, 2026

FDA has granted accelerated approval of Loargys (pegzilarginase-nbln), an arginine specific enzyme indicated for the treatment of hyperargininemia in adult and pediatric patients ≥2 years of age with arginase 1 deficiency (ARG1-D), in conjunction with dietary protein restriction.

According to a manufacturer press release, this indication is approved under accelerated approval based on reduction of plasma arginine. Continued approval may be contingent upon verification and description of clinical benefit in a confirmatory trial.

Pegzilarginase is a novel, recombinant, human arginase-1 enzyme that’s been shown to rapidly and sustainably lower levels of the amino acid arginine and its toxic metabolites in plasma.

Efficacy

Approval was based on data from the randomized, double-blind, placebo-controlled phase 3 PEACE trial (NCT03921541) in which 32 patients were randomized 2:1 to receive IV Loargys (n=21) or placebo (n=11) once weekly for 24 weeks.

Loargys-treated patients received an initial dosage of 0.1 mg/kg and were titrated within a range of 0.05 mg to 0.2 mg/kg, as clinically indicated. A total of 31 patients completed the double-blind period; one patient in the LOARGYS arm discontinued for personal reasons. The primary endpoint was the change from baseline in plasma arginine at week 24.

Loargys-treated patients had a significant mean reduction in plasma arginine levels from baseline to week 24. Additionally, 90% of Loargys-treated patients achieved target plasma arginine levels (<200 μM) and normalized levels, compared with 0% of placebo-treated patients.

All 31 patients (n=20 Loargys and n=11 placebo) who completed the double-blind period entered the 150-day extension period and received open-label treatment of Loargys.

During the extension period, patients who switched from placebo to Loargys achieved similar reductions in mean plasma arginine levels as those who’d received Loargys from the start of the study.

Safety

The most common adverse reactions (>10%) include vomiting, pyrexia, infusion-associated reactions. and constipation.

Sources:

US FDA has granted accelerated approval of Loargys® (pegzilarginase-nbln) for the treatment of hyperargininemia in patients 2 years and older with arginase 1 deficiency (ARG1-D). [News release]. 2026. https://www.immedica.com/en/press/us-fda-has-granted-accelerated-approval-loargysr-pegzilarginase-nbln-treatment

Loargys (pegzilarginase-nbln) [package insert]. Immedica. https://www.immedicaus.com/sites/default/files/pr/highlights-of-prescribing-information-loargys.pdf Revised February 2026. Accessed February 24, 2025.