BioMarin secures global rights to HM15421/GC1134A in a $475 million deal, advancing a long-acting enzyme replacement candidate for Fabry disease.
Written By: Siddhi Bhadekar, M. Pharm (QA)
Reviewed By: Pharmacally Editorial Team
BioMarin announced on October 29, 2026, an exclusive worldwide licensing agreement, excluding South Korea, with GC Biopharma and Hanmi Pharm for HM15421/GC1134A, an investigational long-acting enzyme replacement therapy (ERT) for Fabry disease.
The candidate is a recombinant human alpha-galactosidase A (α-Gal A) enzyme currently being evaluated in a Phase 1/2 clinical trial (NCT06858397). BioMarin believes the therapy could become the first subcutaneous ERT for Fabry disease, although its clinical performance remains to be established.
Phase 1/2 Trial Evaluates Safety, Pharmacokinetics and Efficacy
The first-in-human Phase 1/2 study is an open-label, dose-ranging proof-of-concept trial evaluating HM15421/GC1134A in adults with Fabry disease. The study has an estimated enrollment of 18 participants and evaluates three sequential dose cohorts: low, middle and high. Participants receive the investigational enzyme subcutaneously.
The primary assessment focuses on the incidence and characteristics of adverse events. Secondary assessments include pharmacokinetic parameters, such as maximum serum concentration and terminal elimination half-life, alongside pharmacodynamic measures involving plasma and urine globotriaosylceramide (Gb3) and lyso-Gb3 levels, and changes in estimated glomerular filtration rate (eGFR).
The study began in May 2025, with completion estimated for August 2028. Eligibility criteria include symptomatic, documented Fabry disease, no Fabry-specific treatment during the preceding six months, negative anti-drug antibody testing at screening, eGFR of at least 60 mL/min/1.73 m² and plasma lyso-Gb3 above 1.5 times the upper limit of normal. The renal-function threshold limits the initial study population’s representation of patients with advanced kidney impairment.
$475 Million Agreement Expands BioMarin’s Fabry Disease Portfolio
Under the agreement, BioMarin will pay $70 million upfront, while GC Biopharma and Hanmi Pharm are jointly eligible to receive up to an additional $405 million in development and commercial milestone payments, along with tiered royalties on net sales. The combined upfront and milestone consideration could reach $475 million, excluding royalties.
Following completion of the ongoing Phase 1/2 study, BioMarin will assume sole responsibility for subsequent clinical development, manufacturing and commercialization outside South Korea. GC Biopharma and Hanmi will retain commercialization rights within South Korea.
BioMarin CEO Alexander Hardy described the agreement as building on the company’s acquisition of Amicus Therapeutics earlier in 2026. The candidate could expand BioMarin’s reach beyond patients with GLA mutations amenable to GALAFOLD (migalastat), the oral Fabry disease treatment added through the Amicus acquisition.
Long-Acting Enzyme Design Supports Subcutaneous Development
HM15421/GC1134A is designed to extend enzyme half-life and improve stability relative to currently available ERTs, supporting subcutaneous administration. Existing Fabry ERTs are administered intravenously, making a subcutaneous formulation a potential change in treatment delivery and patient convenience.
BioMarin also reported differentiated preclinical efficacy across renal function, vascular health and peripheral nervous system outcomes. However, the company has not disclosed quantitative preclinical results in its licensing announcement. These findings therefore remain preclinical observations rather than evidence of clinical benefit.
The candidate received U.S. Food and Drug Administration (FDA) Orphan Drug Designation in 2024, according to BioMarin. This designation provides incentives for developing treatments for rare diseases, including qualifying clinical-trial tax credits, user-fee exemptions and potential seven-year market exclusivity following approval. It does not establish safety or efficacy.
Fabry Disease and the Unmet Treatment Need
Fabry disease is an X-linked lysosomal storage disorder caused by inherited changes in the GLA gene, resulting in deficient α-Gal A activity. The resulting accumulation of globotriaosylceramide (GL-3) within lysosomes contributes to disease manifestations, including pain, progressive kidney damage and increased cardiovascular risk, including heart attack and stroke.
Treatment options include intravenous ERT and migalastat for patients with amenable GLA variants. An enzyme-based treatment with subcutaneous administration could potentially broaden treatment choices beyond the population eligible for migalastat.
Clinical Interpretation
The agreement expands BioMarin’s Fabry disease portfolio with a long-acting enzyme replacement candidate that could offer greater administration convenience through subcutaneous delivery. The Phase 1/2 study will provide initial insights into its safety, tolerability, pharmacokinetics and effects on disease-related biomarkers. Further development will determine whether these properties translate into meaningful clinical benefits and establish its potential role alongside existing Fabry disease treatments.
References
BioMarin Pharmaceutical Inc. BioMarin Enters into Exclusive Worldwide License Agreement with GC Biopharma and Hanmi Pharm for Investigational Next-Generation Enzyme Replacement Therapy, Adding a Second Potential Treatment for Fabry Disease. Press release. October 29, 2026.
A proof-of Concept Study to Assess Safety and Tolerability of HM15421/GC1134A in Patients with Fabry Disease, ClinicalTrials.gov ID NCT06858397
About the Writer
Siddhi Rajendra Bhadekar (Linkedin) is an M.Pharm professional with expertise in medical and scientific writing, literature review, publication writing, and evidence synthesis, supported by four peer-reviewed publications.
She brings working knowledge of ICH-GCP, MedDRA, pharmacovigilance, ADR/AE reporting, clinical data management, and regulatory documentation.
With experience across pharmaceutical R&D, Quality Control, and Quality Assurance, she combines scientific research skills with strong attention to accuracy and detail.
Her background in manuscript development, publication planning, and scientific communication enables her to translate complex healthcare information into clear, reliable content.