In the past, Crysvita was approved for subcutaneous administration by a physician for patients with X-linked hypophosphatemia (XLH). This injection could be both invasive and time-consuming. However, according to the Pharma Times, the European Union (EU) recently approved a self-administered Crysvita option.
According to Kyowa Kirin, Crysvita is:
a recombinant fully human monoclonal IgG1 antibody against the phosphaturic hormone fibroblast growth factor 23 (FGF23). By blocking excess FGF23 in patients, Crysvita® is intended to increase phosphate reabsorption in the kidney and increase the production of vitamin D, which enhances intestinal absorption of phosphate and calcium in patients with X linked hypophosphatemia.
With this new approval, patients or caregivers may now be able to self-administer treatment. Although the first dose would be administered by a physician, and the first self-administered dose under the watch of a physician, patients may later be able to dose themselves at home. Ultimately, this improves patient care by offering an easier, yet still effective, manner of treatment.
Crysvita is designed for pediatric patients (ages 1-17) with XLH, as well as adults.
X-Linked Hypophosphatemia (XLH)
PHEX gene mutations on the X chromosome cause X-linked hypophosphatemia (XLH), an inherited disorder characterized by abnormally low phosphate levels in the blood. Overall, PHEX mutations can increase fibroblast growth factor 23 (FGF23) levels. Normally, FGF23 acts as a growth hormone and regulates phosphate reabsorption in the kidneys. However, PHEX mutations and high FGF23 concentrations cause phosphate wasting and soft, weakened bones (rickets). Although XLH is often inherited, the condition is caused by spontaneous gene mutations in up to 30% of diagnoses. In many cases, XLH is diagnosed in childhood. Symptoms of XLH, which vary in severity, include:
- Bowed or bent legs
- Joint, bone, muscle, or tooth pain
- Premature fusion of skull bones (craniosynostosis)
- Frequent or easy bone fractures
- “Waddling” gait
- Short stature
- Dental abcesses
- Easily dislocated joints
- Tendon and ligament calcification
- Rachitic rosary
- Hip bone abnormalities
- Hearing loss
- Spinal stenosis
- Limited mobility