JKU Study: New Drug Revolutionizes Treating Rare Bone Disease

A recent JKU study is taking a closer look at how to better treat phosphate diabetes, a rare hereditary disease.

Prof. Högler, Photo credit: KUK
Prof. Högler, Photo credit: KUK

Approximately 1 in 20,000 suffers from phosphate diabetes. Those afflicted suffer from rickets, soft bones, and leg deformities. According to a recent study conducted by the Johannes Kepler University of Linz, a new, recently approved drug is revolutionizing how the disease is being treated. The study has been published in the renowned medical journal "The Lancet".

Fibroblast Growth Factor 23 is a hormone that was originally discovered by researchers at the Indiana School of Medicine (USA). Those suffering from phosphate diabetes have excessively high concentrations of this hormone. Burosumab is a new drug that can block this particular hormone. Recently been approved by the European Medicines Agency, Burosumab is being used to treat X-chromosomal hypophosphatemia (phosphate diabetes). Whether or not this approach is more effective than conventional treatments over the past 60 years had been was unclear.

Extensive Study
Prof. Dr. Wolfgang Högler, JKU Faculty of Medicine and head of the Department of Pediatrics and Adolescent Medicine at the Kepler University Hospital, explained: "In addition to rickets, this defect also resulted in stunted growth, deformed legs, tooth abscesses, and bone pain." Together with a team of researchers, Prof. Högler spent a number of years studying 61 children ranging in age between 1 and 12 years old from 16 international centers. The children were randomly assigned to two treatment groups and received either Burosumab or conventional treatment (consisting of an oral intake of phosphate and activated vitamin D several times a day). Radiologists evaluated the x-ray images and determined an improvement of rickets. The experts did not know which treatment group the images came from.

Success in Less Than a Year
The children received 64 weeks of treatment. Even after just 40 weeks of treatment, researchers observed that 72% of the children receiving Burosumab injections were substantially cured of rickets. On the other hand, only 6% of the children receiving conventional treatment showed any improvement. Burosumab also improves leg deformities, stunted growth, distance covered in a 6-minute walking test, and blood tests showed phosphate and active vitamin D.

Dr. Högler added, "This is the first study that directly compares Burosumab to conventional treatment. We now know the magnitude of Burosumab’s advantages compared to conventional treatment. This information is essential for physicians when deciding how to best treat their XLH patients."

Plans for Additional Studies
The findings have now been published in the renowned medical journal "The Lancet". Next, the research group plans to study longer-term effects of Burosumab as well as how treatment in childhood affects height and health as an adult. Prof. Högler remarked, "Above all, we want to know whether or not this treatment can also reduce the need to perform operations on deformed legs."