BioMarin’s stock inched up yesterday on news that it has gained access to a potential new Pompe disease drug by snapping up private biotech ZyStor Therapeutics in a deal worth up to $115 million.

The Novato, California-based biopharmaceutical group is shelling out an initial $22 million for the group, which focuses on the development of enzyme replacement therapies for lysosomal storage disorders, but could pay up to an additional $93 million if certain development, regulatory and commercial milestones are achieved.

ZyStor’s most advanced asset is ZC-701, a novel fusion of insulin-like growth factor 2 and alpha glucosidase (IGF2-GAA), which is in development for Pompe disease. The US Food and Drug Administration has already accepted an Investigational New Drug filing for the drug, which will be tested in the clinic in the first quarter of next year.

In vitro studies have been promising, showing that ZC-701 has more than ten times higher affinity for the mannose-6-phosphate receptor compared to Genzyme’s Myozyme (alglucosidase alfa), enabling delivery of higher levels of enzyme to the lysosomes of muscle cells of Pompe patients. This is thought to be an important factor, as many experts believe an enzyme with better uptake into muscle cells would increase the efficiency of treatment, BioMarin noted.

According to Jean-Jacques Bienaime, chief executive of BioMarin, ZC-701 is a “superior product” that, relative to its own internal candidate for Pompe, BMN-103, “has a faster clinical development timeline, lower development costs, significantly lower cost of goods and lower capital investment”, making it a very attractive addition to its pipeline.

And given that early indications (from mouse models) are that ZC-701 is more effective than commercially available replacement enzymes for Pompe disease, the company will certainly be hoping for a substantial slice of the market, which is estimated to be worth more than $1.0 billion.