BioMarin’s Gene Therapy for Hemophilia A Approved by United States FDA

The U.S. Food and Drug Administration on Thursday approved BioMarin Pharmaceutical’s (BMRN.O) gene therapy for severe hemophilia A, the company said, giving patients with the inherited bleeding disorder an alternative to regular injections of missing blood proteins.

It priced the one-time therapy, Roctavian, at $2.9 million. Pivotal trial results showed that Roctavian reduced bleeding events, but its durability is not known, and the company said it would include a warranty to health insurers.

BioMarin said most study participants continued to respond to the gene therapy through year three and beyond, and it would continue to monitor them for 15 years.

Gene therapies use a deactivated virus to deliver the needed genes and the immune system would recognize and eliminate a second dose of the therapy.

The company said it would offer all U.S. health insurers a “warranty”, under which it would reimburse the wholesale cost if a patient does not respond. The company said the reimbursement would be “pro-rated” for patients that stopped responding in the first four years after treatment.

Roctavian is the first gene replacement therapy for the most common form of hemophilia, enabling patients a way to forego or reduce the need for lifetime treatment with factor proteins needed to help blood clot or with monthly doses of a newer antibody drug.

Shares of the California-based company closed 3.6% lower on Thursday.

The approval was pretty widely expected and now there is debate on how the uptake will pan out, said Joel Beatty, senior research analyst at Robert W Baird.

Roctavian, which is manufactured at the company’s facility in Novato, California, works by delivering a functional copy of the missing gene that would help hemophilia A patients make a blood-clotting protein known as factor VIII.

“Roctavian’s launch will probably be a little slow at first, because there are already some effective treatment options on the market. But longer-term, one-time dosing will likely end up being attractive to a lot of patients,” Beatty added.

BioMarin’s therapy will compete for market share with Roche’s (ROG.S) Hemlibra, an antibody drug which mimics the function of the blood clotting protein missing in hemophilia A patients.

Roctavian was approved for hemophilia A in the European Union last year, and is sold under the same brand name.

In April, BioMarin cut its annual sales forecast range for Roctavian to $50 million to $100 million, from $100 million to $200 million.

The company said on Thursday it expects about 2,500 of around 6,500 adults living with severe hemophilia A in the United States to be eligible to receive Roctavian with this initial approval.

There are about 16,000 patients in the United States with hemophilia A in which they are missing the factor VIII clotting protein.,protein%20known%20as%20factor%20VIII