FDA approves first drug for rare disease that causes low phosphate blood levels, bone softening

The US Food and Drug Administration has approved Crysvita (burosumab-twza) injection to treat patients age two and older with tumor-induced osteomalacia (TIO), a rare disease that is characterized by the development of tumors that cause weakened and softened bones.

The FDA granted approval of Crysvita to Ultragenyx Pharmaceutical (Nasdaq: RARE), a specialist in rare and ultra-rare diseases that agreed terms with Japan-based Kyowa Kirin (TYO: 4151) in 2013 for a collaboration to develop and license the therapy. Analysts expect that Crysvita could generate sales of up to a billion dollars at peak, with more than half of the revenue going to its originator, Kyowa Kirin. Ultragenyx shares closed up1.4% at $72.48 on the news yesterday

“As the first FDA-approved therapy to treat this debilitating disease, today’s action is an important step in finding treatment options for patients living with TIO whose tumor cannot be found or removed,” commented Dr Theresa Kehoe, acting director of the FDA’ Division of General Endocrinology.