FDA Approves First Therapy for Tumour-Induced Osteomalacia

June 20, 2020

The US Food and Drug Administration (FDA) approved burosumab-twza (Crysvita) injection to treat patients aged 2 years and older with tumour-induced osteomalacia (TIO).

“Treatment for TIO focuses on identifying and removing the tumour that causes the disease; however, when that is not possible, [burosumab-twza] can help increase the levels of phosphate in the blood,” said Theresa E. Kehoe, MD, FDA’s Center for Drug Evaluation and Research, Rockville, Maryland. “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.”

The safety and efficacy of burosumab-twza were evaluated in 2 studies that together enrolled 27 adults with TIO. In both studies, patients received burosumab-twza every 4 weeks. For the first study, half of patients achieved normal phosphate levels through week 24 and maintained normal or near normal phosphate levels through week 144. In the second study, 69% of participants achieved normal phosphate levels through week 24 and maintained normal or near normal phosphate levels through week 88. The results of bone scans for patients in the first study also suggested healing of the bone lesions related to osteomalacia.

Hypersensitivity reactions such as rash and hives have been reported in patients who took burosumab-twza. If serious hypersensitivity reactions occur, patients should stop treatment and talk with their healthcare provider about further medical treatment. Higher than normal levels of phosphorus may be associated with an increased risk of nephrocalcinosis.

The most common adverse events were tooth abscess, muscle spasms, dizziness, constipation, injection site reaction, rash, and headaches.

Patients taking oral phosphate or active vitamin D, those who have serum phosphate levels within or above the normal range for their age, and patients with severe kidney impairment or end-stage renal disease should not take burosumab-twza.

Reference: https://www.fda.gov/news-events/press-announcements/fda-approves-first-t...

SOURCE: US Food and Drug Administration