BioMarin pays $70m upfront for GC Biopharma and Hanmi's subcutaneous Fabry enzyme therapy

BioMarin Pharmaceutical said on 29 October 2026 that it has signed an exclusive worldwide licence with GC Biopharma and Hanmi Pharm for HM15421/GC1134A, an investigational long-acting enzyme replacement therapy for Fabry disease¹. BioMarin will pay $70 million upfront, and the two Korean companies are jointly eligible for up to $405 million more on development and commercial milestones, plus tiered royalties on net sales¹.

The asset and the terms

HM15421/GC1134A is a recombinant human alpha-galactosidase A enzyme, the enzyme that people with Fabry disease lack¹. It is engineered for a longer half-life and better stability than current enzyme replacement therapies so that it can be given under the skin, and BioMarin says it could become the first subcutaneous enzyme replacement therapy for the disease¹. The candidate is in a Phase 1/2 trial and received FDA orphan drug designation in 2024¹. In preclinical work it showed differentiated effects on kidney function, vascular health and peripheral nerve outcomes, according to BioMarin¹.

The split of work is clear. Once the current Phase 1/2 study ends, BioMarin takes sole responsibility for later clinical development, manufacturing and commercialisation everywhere except Korea, where GC and Hanmi keep commercial rights¹.

Alexander Hardy, BioMarin's chief executive, said: "This agreement reflects our growing commitment to the Fabry community, building on the acquisition of Amicus earlier this year"¹. He said the candidate could reach Fabry patients beyond those whose mutations make them suitable for treatment with Galafold¹.

What it means for the market

The deal shows BioMarin building a Fabry franchise through external assets rather than relying on internal research alone. Hardy described the portfolio as growing through both internal research and external programmes, and the licence follows the Amicus acquisition earlier in 2026¹. For investors, the structure keeps most of the value contingent: the $70 million upfront is small next to the $405 million tied to milestones¹.

For Korean drug developers, the agreement is another example of a clinical-stage asset licensed to a larger Western company while home-market rights are retained¹. For competitors in Fabry, the threat is in the delivery route. A subcutaneous option would differ from the enzyme replacement therapies now on the market, which BioMarin positions as the point of difference¹.

BioMarin has not disclosed the size of the Phase 1/2 trial, the timing of its readout, or how the milestone payments are split between development and sales¹.

Caveats

All of the information comes from BioMarin's own announcement, and the claims of differentiated efficacy rest on preclinical studies¹. The candidate has not yet reported clinical efficacy data, and the press release flags the usual risks around trial results, adverse events and decisions by the FDA, the European Medicines Agency and other regulators¹. BioMarin is due to host its third quarter 2026 results call on 2 November 2026¹.