FDA Approves First Therapy for Tumor-Induced Osteomalacia
The U.S.
Food and Drug Administration approved Crysvita (burosumab-twza) injection to treat
patients age two and older with tumor-induced osteomalacia (TIO).
The Food and Drug Administration granted
approval of Crysvita to Ultragenyx Pharmaceutical Inc.
It is a rare disease that is characterized by
the development of tumors that cause weakened and softened bones. The tumors
associated with TIO release a peptide hormone-like substance known as
fibroblast growth factor 23 (FGF23) that lowers phosphate levels.
Treatment
for TIO focuses on identifying and removing the tumor that causes the disease.
However, when that is not possible, Crysvita can help increase the levels of
phosphate in the blood," said Theresa E. Kehoe, M.D., acting director of
the Division of General Endocrinology in the FDA's Center for Drug Evaluation
and Research. "As the first Food and Drug Administration-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."
FGF23 regulates levels of phosphate, an electrolyte that plays important roles in bone maintenance, energy production by cells and nerve function. When there is not enough phosphate in the body, bones begin to soften and weaken, causing osteomalacia (marked softening of bones).
FGF23 regulates levels of phosphate, an electrolyte that plays important roles in bone maintenance, energy production by cells and nerve function. When there is not enough phosphate in the body, bones begin to soften and weaken, causing osteomalacia (marked softening of bones).
The safety
and efficacy of Crysvita were evaluated in two studies that together enrolled
27 adults with TIO. In both studies, patients received Crysvita every four
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 (softening of the
bones).
Hypersensitivity reactions such as rash and hives have been reported in patients who took Crysvita. If serious hypersensitivity reactions occur, patients should stop taking Crysvita and talk with their health care provider about further medical treatment. Additionally, higher than normal levels of phosphorus may be associated with an increased risk of nephrocalcinosis (a disorder that occurs when too much calcium is deposited in the kidneys).
Hypersensitivity reactions such as rash and hives have been reported in patients who took Crysvita. If serious hypersensitivity reactions occur, patients should stop taking Crysvita and talk with their health care provider about further medical treatment. Additionally, higher than normal levels of phosphorus may be associated with an increased risk of nephrocalcinosis (a disorder that occurs when too much calcium is deposited in the kidneys).
The most
common side effects reported in adults with TIO taking Crysvita were tooth
abscess (nfection), 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 Crysvita.
Crysvita is
also Food and Drug Administration -approved to treat
adults and children six
months and older with X-linked
hypophosphatemia, which causes low levels of
phosphate in the
blood and leads to impaired bone growth and development in
children and teenagers.