This photo provided by Genentech, Inc. shows a package of the drug Hemlibra. On Thursday, Nov. 16, 2017, the Food and Drug Administration approved Hemlibra, the first new treatment in nearly two decades to prevent internal bleeding in certain patients with hemophilia, an inherited blood-clotting disorder. (Genentech, Inc. via AP)

U.S. regulators have approved the first new treatment in nearly two decades to prevent internal bleeding in certain patients with hemophilia, an inherited blood-clotting disorder.

The Food and Drug Administration on Thursday approved Hemlibra (hem-LEE'-bruh), a weekly injection for A patients who have developed resistance to standard medicines.

Genentech, the drug's developer, says the list price will be about $482,000 for the first year and slightly less after that.

Genentech, a subsidiary of Swiss drugmaker Roche, says that's half the cost of the only other option for patients with this resistance. That treatment requires an IV drip several times a week.

Hemophilia mostly affects males.