Erik Harris, Executive Vice President and Chief Commercial Officer at Ultragenyx Pharmaceutical Inc. discusses the recent approval of burosumab-twza (Crysvita) for treatment of tumor-induced osteomalacia (TIO).

TIO is a rare disease caused by typically benign, slow-growing tumors that produce excess levels of FGF23, a protein that regulates phosphate reabsorption. TIO patients may experience hypophosphatemia, osteomalacia, muscle weakness, fatigue, bone pain, and bone fractures. Of the 500 to 1,000 TIO patients in the United States, approximately half are considered inoperable. Previously the only treatment available to those who were inoperable was oral phosphate and/or vitamin D replacement, the efficacy of which was limited. 

As Mr. Harris explains, burosumab-twza was first approved in 2018 for the treatment of x-linked hypophosphatemia. Earlier this summer, it was also approved for the treatment of TIO as well. This approval was based on data from two single-arm Phase 2 studies: one 144-week study in 14 adult patients conducted by Ultragenyx in the United States and one 88-week study in 13 adult patients conducted by Kyowa Kirin in Japan and South Korea. In both studies, burosumab-twza was associated with increased phosphate levels which led to improvements in osteomalacia and healing of previous bone lesions.

To learn more about TIO and receive CME credit, click here.



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