FDA

Loargys

Approved 23 Feb 2026InjectionInjectable

Indications

LOARGYS is indicated for the treatment of hyperargininemia in adult and pediatric patients 2 years of age and older with Arginase 1 Deficiency (ARG1-D), in conjunction with dietary protein restriction. This indication is approved under accelerated approval based on reduction of plasma arginine [see Clinical Studies ( 14 )] . Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.

LOARGYS is an arginine specific enzyme indicated for the treatment of hyperargininemia in adult and pediatric patients 2 years of age and older with Arginase 1 Deficiency (ARG1-D), in conjunction with dietary protein restriction. ( 1 ) This indication is approved under accelerated approval based on reduction of plasma arginine. ( 14 ) Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.

( 1 )

Contraindications

None. None. ( 4 )

Warnings and precautions

Hypersensitivity : If a severe hypersensitivity reaction occurs, discontinue LOARGYS and immediately initiate appropriate medical treatment, including epinephrine. ( 5.1 )

5.1Hypersensitivity Reactions Including Anaphylaxis

Life-threatening hypersensitivity reactions, including anaphylaxis, have occurred in patients treated with enzyme replacement therapies (ERTs) including LOARGYS. Hypersensitivity reactions that were mild to moderate in severity occurred in 13% (6/48) of LOARGYS-treated patients in clinical trials [see Adverse Reactions ( 6 )] . Hypersensitivity reactions have included facial swelling, rash, flushing and dyspnea. The reactions generally occurred with the first few doses, but may also occur later in treatment.

LOARGYS-treated patients who developed anti-drug antibodies (ADA) generally had a greater incidence of hypersensitivity reactions compared to those who did not develop ADA [see Adverse Reactions ( 6.1 )] . Anaphylaxis has occurred during the early course of ERT and after extended duration of ERT. Administration of LOARGYS should be supervised by a healthcare provider knowledgeable in the management of hypersensitivity reactions including anaphylaxis.

Consider pre‑medication with an antihistamine. Corticosteroids can be considered in patients who have previously developed a hypersensitivity reaction. Initiate LOARGYS in a healthcare setting with appropriate medical monitoring and support measures, including access to cardiopulmonary resuscitation equipment.

At a glance

Brand name: Loargys
Active substance: pegzilarginase-nbln
Route: Injection
Dosage form: Injectable
Applicant: Immedica Pharma AB
Status: Prescription
FDA approval: 23 Feb 2026
Application: BLA761211-001

Indications

( 1 )

Warnings and precautions

Hypersensitivity : If a severe hypersensitivity reaction occurs, discontinue LOARGYS and immediately initiate appropriate medical treatment, including epinephrine. ( 5.1 )

5.1Hypersensitivity Reactions Including Anaphylaxis

Pregnancy and breastfeeding

8.1Pregnancy Risk Summary

There are no available data on LOARGYS use in pregnant females to evaluate for a drug-associated risk of major birth defects, miscarriage or other adverse maternal or fetal outcomes. In animal reproduction studies, intravenous administration of pegzilarginase-nbln to pregnant rats and rabbits during organogenesis resulted in maternal toxicity with associated increased incidence of fetal growth deficiencies (see Data ) .

The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Animal Data In an embryofetal development study in pregnant rats with normal circulating arginine levels, intravenous pegzilarginase-nbln was administered throughout organogenesis at 0.1, 0.3, and 1 mg/kg/dose on gestation days 6, 11, and 16.

Maternal toxicity was observed as reduced body weight, reduced body weight gain, reduced food consumption and reduced mean gravid uterine weights at 1 mg/kg/dose (8-fold the human exposure, based on AUC at the maximum recommended human dose (MRHD), with associated decreases in fetal body weights and increased fetal developmental malformations and variations at this dose. In an embryofetal development study in pregnant rabbits with normal circulating arginine levels, intravenous pegzilarginase-nbln was administered throughout organogenesis at 0.06, 0.1, and 0.3 mg/kg/dose on gestation days 6, 13, and 20.

Maternal toxicity was observed as decreased maternal body weights, food consumption and mean gravid uterine weights at 0.3 mg/kg/dose (3-fold the human exposure, based on AUC at the MRHD), with associated decreases in fetal body weights and increased developmental malformations and variations at this dose. In a pre- and postnatal development study in pregnant rats with normal circulating arginine levels, intravenous pegzilarginase-nbln was administered at 0.1, 0.3 and 1 mg/kg/dose once weekly from gestation day 6 to lactation day 20.

Maternal toxicity included reduced body weight and food consumption during gestation and lactation with associated reduced pup body weight at 1 mg/kg/dose (8-fold the human exposure based on AUC at the MRHD). Male pups exposed to 1 mg/kg/dose through gestation and lactation also had impaired learning and memory in the passive avoidance test.

Adverse reactions

The following adverse reactions are described below and elsewhere in the labeling:

Hypersensitivity Reactions [see Warnings and Precautions ( 5.1 )] . Most common adverse reactions (>10%) are vomiting, pyrexia, infusion associated reactions and constipation. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Immedica at toll-free phone 1-844-627-4687 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

6.1Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The safety of LOARGYS was evaluated in a randomized, double-blind, placebo-controlled trial in pediatric and adult patients with ARG1-D (Trial 1). Additional safety information was derived from Trial 2, a Phase 1 open-label trial that evaluated 16 patients between the ages of 5 to 31 years to assess safety, PK and PD of LOARGYS, and Trial 3, an open-label extension including 14 patients from Trial 2.

Adverse Reactions from Trial 1 (Double-Blind Period) A total of 21 patients between the ages of 2 and 28 years of age, at enrollment, received intravenous LOARGYS dosages up to 0.2 mg/kg once weekly and 11 patients received placebo for 24 weeks [see Clinical Studies ( 14 )] . Table 1 summarizes the adverse reactions reported in ≥ 2 LOARGYS-treated patients and at a higher incidence in LOARGYS-treated patients compared to placebo-treated patients in Trial 1.

Table 1: Common Adverse Reactions a in Pediatric and Adult Patients with ARG1-D in Trial 1 a Common adverse reactions were those that occurred in ≥ 2 LOARGYS-treated patients and at a higher incidence in LOARGYS-treated patients compared to placebo-treated patients. b Infusion-associated reactions are defined as reactions occurring within 4 hours after the infusion and included pruritus, arm swelling, and abdominal pain in LOARGYS-treated patients. c Includes reactions that were classified as hypersensitivity during the trial and reactions that were assessed as hypersensitivity based on symptoms and temporal relationship with drug.

Adverse Reaction LOARGYS N = 21 n (%) Placebo N = 11 n (%) Vomiting 7 (33) 3 (27) Pyrexia 4 (19) 1 (9) Infusion Associated Reaction b 3 (14) 1 (9) Constipation 3 (14) 1 (9) Dizziness 2 (10) 0 Fall 2 (10) 0 Hypersensitivity c 2 (10) 0 Nasopharyngitis 2 (10) 0 Rhinorrhoea 2 (10) 0 Alanine aminotransferase increased 2 (10) 0 Aspartate aminotransferase increased 2 (10) 0 Description of Selected Adverse Reactions Hypersensitivity Reactions : Hypersensitivity reactions with symptoms including facial swelling, rash, flushing and dyspnea were reported in 13% (6/48) of LOARGYS-treated patients during clinical trials [see Warnings and Precautions ( 5.1 )] .

Injection Site Reactions : Injection site reactions were reported in 14% (6/44) of patients after subcutaneous LOARGYS administration during the open-label extension periods in Trial 1 and Trial 3. Signs and symptoms included pain, erythema, swelling, irritation, and rash at the injection site. Immunogenicity: Anti-Drug Antibody-Associated Adverse Reactions Across Trials 1, 2, and 3, in patients with ARG1-D, the incidence of hypersensitivity reactions was 42% (5/12) in LOARGYS-treated patients who developed anti-drug antibodies (ADA) (i.e., anti-pegzilarginase-nbln antibodies and/or anti-PEG antibodies) and 3% (1/36) in those who were ADA-negative [see Clinical Pharmacology ( 12.6 )] .

Loargys

Indications

Contraindications

Warnings and precautions

5.1Hypersensitivity Reactions Including Anaphylaxis

At a glance

Two medicines in one question?

Loargys

Indications

Contraindications

Warnings and precautions

5.1Hypersensitivity Reactions Including Anaphylaxis

At a glance

Two medicines in one question?

Pregnancy and breastfeeding

8.1Pregnancy Risk Summary

Adverse reactions

6.1Clinical Trials Experience

Composition

Official product information