U.S. 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)
PR Newswire
STOCKHOLM and CHICAGO, Feb. 23, 2026
- LOARGYS is the first and only therapy proven to lower arginine in patients 2 years of age and older living with ARG1-D
- ARG1-D is an ultra-rare, debilitating, and progressive metabolic disease resulting in persistent elevation of plasma arginine, also known as hyperargininemia
- FDA accelerated approval of LOARGYS is based on positive results from the Phase 3 PEACE trial where LOARGYS significantly reduced plasma arginine from baseline compared to placebo at 24 weeks
STOCKHOLM and CHICAGO, Feb. 23, 2026 /PRNewswire/ -- Immedica Pharma today announced that the U.S. Food and Drug Administration (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 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. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.
"Today's FDA accelerated approval of LOARGYS is an important milestone for Immedica and for patients and families affected by Arginase 1 Deficiency in the U.S.," said Anders Edvell, CEO of Immedica. "This outcome is the result of collaborative efforts across the entire ARG1-D community including patients, advocacy groups, researchers, and clinicians. We are proud to be able to deliver a treatment option for patients and families who have long awaited progress."
ARG1-D affects an estimated 250 people living in the U.S. and current standard of care relies primarily on symptom management, including dietary protein restriction, arginine-free amino acid supplementation and nitrogen scavenging agents if necessary.
"Until now, the care of patients with Arginase 1 Deficiency has been limited to symptomatic management and strict dietary control. The accelerated approval of LOARGYS offers a fundamentally new approach that addresses the enzyme deficiency itself. Since persistently elevated arginine and its metabolites have been reported to be the proximal or direct driver of disease progression, this is a major advancement in metabolic medicine" said Dr. Stephen Cederbaum, Professor Emeritus of Human and Medical Genetics at UCLA.
LOARGYS is the first and only treatment to address persistently elevated levels of plasma arginine, the primary driver of ARG1-D.
Christine Zahn, founder and director of Arginase 1 Deficiency Foundation added, "Today marks a pivotal moment for the ARG1-D community and the physicians who support us. While the journey to this day was neither short nor simple, LOARGYS offers real hope for a better future and exemplifies what is possible when progress driven by empathy, collaboration, and relentless advocacy to address patients in need."
To support access to treatment, Immedica is launching There for Rare, a patient support program providing nonmedical education to help eligible individuals prescribed LOARGYS navigate each stage of the treatment journey, including financial assistance options.
LOARGYS is estimated to be available in the U.S. in April 2026.
For more information about LOARGYS, visit www.loargys.com.
About ARG1-D
ARG1-D is an ultra-rare and serious inherited metabolic disorder. The principal defect in ARG1-D leads to accumulation of plasma arginine (hyperargininemia,) and its toxic metabolites. Patients are often diagnosed in late infancy or early childhood, and the symptoms include spasticity, seizures, developmental delay, intellectual disability, and early mortality. ARG1-D is one of the eight urea cycle disorder (UCD) subtypes. It shares some overlapping features with other UCDs, including impaired nitrogen excretion. However, in ARG1-D, hyperammonemia is generally less severe.
About Loargys® (pegzilarginase-nbln)
LOARGYS is a novel, recombinant, human arginase-1 enzyme that has been shown to rapidly and sustainably lower levels of the amino acid arginine and its toxic metabolites in plasma, making it the first and only therapy proven to lower plasma arginine. LOARGYS is approved 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. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.
IMPORTANT SAFETY INFORMATION
WARNING: HYPERSENSITIVITY REACTIONS INCLUDING ANAPHYLAXIS
See full prescribing information for complete boxed warning
Initiate LOARGYS in a healthcare setting with appropriate medical monitoring and support measures, including access to cardiopulmonary resuscitation equipment. If a severe hypersensitivity reaction (e.g., anaphylaxis) occurs, discontinue LOARGYS, and immediately initiate appropriate medical treatment, including use of epinephrine.
WARNINGS AND PRECAUTIONS
Hypersensitivity Reactions Including Anaphylaxis: Life-threatening hypersensitivity reactions, including anaphylaxis, have occurred in patients treated with enzyme replacement therapies, including LOARGYS. Hypersensitivity reactions that were mild to moderate in severity occurred in 13% (6/48) of LOARGYS-treated subjects in clinical trials.
Hypersensitivity reactions have included facial swelling, rash, flushing and dyspnea. The reactions generally occurred with the first few doses but may occur later in treatment.
Administration of LOARGYS should be supervised by a healthcare provider knowledgeable in the management of hypersensitivity reactions including anaphylaxis in a healthcare setting with appropriate medical monitoring and support measures. Premedication with an antihistamine and/or corticosteroid should be considered in patients who previously have developed a hypersensitivity reaction. If a severe hypersensitivity reaction (e.g., anaphylaxis) occurs, discontinue LOARGYS and immediately initiate appropriate medical treatment, including use of epinephrine. Consider the risks and benefits of re-administering LOARGYS in patients who have experienced a severe hypersensitivity reaction. Caution should be exercised upon rechallenge. Inform patients of the symptoms of life-threatening hypersensitivity reactions and to seek immediate medical attention should symptoms occur. If a mild or moderate reaction occurs, consider treatment with antihistamines and/or corticosteroids.
ADVERSE REACTIONS
The most common adverse reactions are vomiting, pyrexia, infusion associated reactions and constipation.
USE IN SPECIFIC POPULATIONS
Pregnancy: 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.
Lactation: There is no data on the presence of LOARGYS in either human or animal milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for LOARGYS and any potential adverse effects on the breast-fed infant from LOARGYS or from the underlying maternal condition.
Pediatric: The safety and effectiveness of LOARGYS have been established for the reduction of plasma arginine in pediatric patients 2 years and older with ARG-1 D, in conjunction with dietary protein restriction. The safety and effectiveness of LOARGYS have not been established for the reduction of plasma arginine in pediatric patients aged less than 2 years with ARG-1 D.
Geriatric: Clinical studies of LOARGYS did not include subjects 65 years of age and older to determine whether they respond differently from younger adult subjects.
INDICATION
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.
This indication is approved under accelerated approval based on reduction of plasma arginine. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.
Please see full Prescribing Information for LOARGYS.
About Immedica Pharma US Inc.
Immedica Pharma US Inc. is an affiliate of Immedica Pharma AB, a pharmaceutical company, headquartered in Stockholm, Sweden. Immedica is focused on the commercialization of medicines for rare diseases and specialty care products. Immedica's capabilities cover marketing and sales, compliance, pharmacovigilance, quality assurance, regulatory, medical affairs and market access, as well as a global distribution network serving patients in more than 50 countries. Immedica is fully dedicated to helping those living with diseases which have a large unmet medical need. Immedica's therapeutic areas are within RARE metabolic, RARE hematology & oncology, RARE neurology, RARE endocrinology, and specialty care. Immedica was founded in 2018 and employs today around 180 people across Europe, the Middle East, and the United States. Immedica is backed by the investment firms KKR and Impilo.
For more information visit www.ImmedicaUS.com.
Immedica contact:
Linda Holmström
VP, Head of HR & Communication
linda.holmstrom@immedica.com
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