Carlsbad drugmaker Ionis Pharmaceuticals Inc. has earned a $50 million check from its global partner Biogen. That’s because a drug developed in Ionis’ labs just got the green light to sell in the European Union.

The drug, called Spinraza, is for the treatment of spinal muscular atrophy in infants. The rare disease drug could potentially be a $2 billion franchise, according to industry analysts.

Other than the new $50 million milestone payment from Biogen, Ionis is also eligible to get tiered royalties on global sales of Spinraza.

Biogen licensed the global rights to develop, manufacture and commercialize Spinraza back in August 2016, and is now responsible for all regulatory, development and commercialization costs related to the drug.

To date, the local company has already earned $375 million from Biogen in payments related to Spinraza.