When BioMarin first got into the gene therapy field in 2013, no one at the company knew how to make viral vectors, the engineered viruses needed to ferry repair genes into cells. So it contracted out the manufacturing of its experimental hemophilia therapy for its Phase I and Phase II studies. But as the company was preparing for its late-stage trial, it decided it needed its own manufacturing facility.
BioMarin believes it will eventually be able to pump up production from the current 170 patients a year in its Phase III trial to 3,000. But whether it and other companies can manufacture enough of the vectors as new gene therapies hit the market for increasingly common diseases is a crucial question for the drug industry.