ABO-101 Gene Editing Therapy for Primary Hyperoxaluria Type 1 Granted Orphan Drug Designation by European Commission
Key Insights
The European Commission has granted Orphan Drug Designation to ABO-101, an investigational gene editing therapy for primary hyperoxaluria type 1 (search) developed by Chiesi Group (search) and Arbor Biotechnologies (search).
ABO-101 is a one-time liver-directed CRISPR-based therapy targeting the HAO1 (search) gene to permanently reduce hepatic oxalate production, addressing the root cause of PH1.
The therapy is currently being evaluated in the global Phase 1/2 redePHine clinical study, with program updates to be presented at the 15th International Hyperoxaluria Workshop on June 26, 2026.
Chiesi Group (search) and Arbor Biotechnologies (search) announced on June 25, 2026, that the European Commission (EC) has granted Orphan Drug Designation (ODD) to ABO-101, an investigational gene editing therapy for the treatment of primary hyperoxaluria (PH). ABO-101 is being developed specifically for primary hyperoxaluria type 1 (search) (PH1), the most common and severe form of PH, which can lead to recurrent kidney stones, kidney failure, and systemic complications. The designation marks a significant inflection point in the companies' global strategic collaboration, established in 2025, to develop and commercialize novel gene editing therapies for rare diseases.
"Receiving Orphan Drug Designation from the EC is an important recognition of the unmet need that exists for people living with PH1 and the promise of what gene editing approaches may offer," said Mitch Goldman, MD, PhD, SVP Research & Development, Chiesi Global Rare Diseases. "Beyond that recognition, the designation provides meaningful support throughout the development lifecycle, which allows us to continue advancing this research with the resources and commitment the community deserves."
Orphan Drug Designation and Regulatory Context
ODD in the European Union is granted to medicines intended for the diagnosis, prevention, or treatment of rare conditions affecting fewer than five in 10,000 people. The designation provides meaningful support throughout the development lifecycle, including protocol assistance, fee reductions, and market exclusivity upon approval.
In addition to the EC's designation, ABO-101 received both ODD and Rare Pediatric Disease Designation (RPDD) from the U.S. Food and Drug Administration (FDA) in 2025. In the United States, the FDA grants ODD to drugs and biologics intended for rare diseases affecting fewer than 200,000 people, while RPDD is granted to therapies intended to treat or prevent serious or life-threatening rare diseases that primarily affect children from birth to 18 years of age.
"This designation underscores the growing potential of gene editing therapies to evolve the treatment landscape for rare genetic diseases," said Devyn Smith, Ph.D., Chief Executive Officer of Arbor Biotechnologies (search). "As we continue advancing the ABO-101 clinical trial program alongside Chiesi, we remain focused on advancing innovative genetic medicines for people living with rare diseases and delivering on our commitment to address significant unmet medical needs."
Disease Background: Primary Hyperoxaluria Type 1 (search)
Primary hyperoxaluria type 1 (search) is an ultra-rare lifelong genetic disease caused by a mutation in the AGXT (search) gene. This mutation leads to an enzyme deficiency in the liver, resulting in overproduction of oxalate and eventual buildup of oxalate crystals in the kidney and other organ systems. As the disease progresses, patients can experience recurring kidney stones, kidney damage, and eventually end-stage kidney disease (ESKD) and systemic oxalosis. Patients may ultimately require intensive interventions such as dialysis and/or transplantation.
ABO-101: Mechanism and Design
ABO-101 is an investigational gene editing therapy designed as a one-time liver-directed intervention that potentially results in a permanent loss of function of the HAO1 (search) gene in the liver, thereby reducing PH1-associated oxalate production. The therapy consists of a lipid nanoparticle (LNP), licensed from Acuitas Therapeutics, encapsulating messenger RNA that expresses a novel Type V CRISPR Cas12i2 nuclease and an optimized guide RNA specifically targeting the human HAO1 gene.
ABO-101 has not been approved for any use by the FDA or any other regulatory agency, including the European Medicines Agency (EMA) and the UK's Medicines and Healthcare products Regulatory Agency (MHRA).
The redePHine Phase 1/2 Clinical Study
ABO-101 is currently being evaluated in the global redePHine Phase 1/2 clinical study (NCT06839235), an open-label, multi-center dose escalation study designed to evaluate safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy of a single dose of ABO-101 in participants with PH1.
The trial consists of two study periods. During the first study period, Part A will treat adult participants with a single ascending dose to identify a recommended dose, while Part B will treat pediatric participants with the recommended dose. Following the first study period, participants will enter Study Period 2, a long-term monitoring program to comply with local and national requirements.
Program updates will be presented at the upcoming 15th International Hyperoxaluria Workshop on June 26, 2026, in Prague, where John Lieske, M.D., Principal Investigator of the redePHine study, will deliver an overview titled "redePHine: Advancing Gene Editing for Primary Hyperoxaluria Type 1 (search)."