Since the use of the drug by XLH patients wasn't officially studied prior to the drug's approval, it's considered an "off-label" use, which raises a number of issues. First, insurance companies can be reluctant to pay for off-label use. Second, not all doctors treating XLH patients even know that it's an off-label use. Third, and most important, scientists don't even know for sure that it's effective on our form of parathyroidism, what an optimal dose is, or whether it might also help reduce our phosphorus wasting.
Dr. Rachel Gafni, at the National Institutes of Health, has been studying the use of Cinacalcet specifically in XLH patients. Until recently, the study was only open to patients living within a fairly small radius of D.C. The study has been expanded recently to include patients from all over the U.S., with travel expenses to be reimbursed according to NIH guidelines.
Information provided by the principal investigator, with contact information:
- NIH Research Study: Open-label Dose-titration Study of the Tolerability and Efficacy of Cinacalcet to Treat Fibroblast Growth Factor 23 (FGF23)-mediated Hypophosphatemia
- Principal Investigator: Dr. Rachel Gafni, MD
- Sponsoring Institute: Craniofacial and Skeletal Diseases Branch, NIDCR, National Institutes of Health
- The purpose of this study is to see how treatment with a drug called cinacalcet affects people with low blood phosphorus (hypophosphatemia) caused by hypophosphatemic rickets or tumor-induced osteomalacia. Studies have suggested that cinacalcet may decrease phosphorus loss by the kidneys in these disorders. If the cinacalcet works, the blood level of phosphorus may be higher. This could result in patients needing less phosphorus medication. It may also help the bones become stronger.
- This study will help us figure out the best dose of cinacalcet and how many times a day it should be taken. Individuals who qualify for the study will take cinacalcet in addition to vitamin D and phosphorus. Many of the study visits will be at the NIH Clinical Center in Bethesda, Maryland. Some of the blood and urine tests may be done at a facility that is closer to the patient’s home. There will be up to 3 inpatient visits and a number of outpatient clinic and lab visits.
- Once cinacalcet therapy is started, there will be 3 - 5 visits with a physician every 3 weeks over a 4- to 7-month period. During the NIH visits, participants will undergo several assessments, which may include a dental evaluation, blood tests, urine tests, x-rays, and questionnaires. Patients will be paid for participation in this study and will be reimbursed for travel expenses, according to NIH policy. You may be eligible if you are between 18 and 70 years of age and have been diagnosed with low blood phosphorus. For more information, please contact the NIH Patient Recruitment and Public Liaison hotline at 1-800-411-1222 or firstname.lastname@example.org.
The XLH Network, Inc. does not endorse or critique specific clinical trials, and does not counsel individual patients either for or against participation in any specific clinical trial. Prospective volunteers should always carefully review the clinical trial's informed consent documentation and protocol, and discuss the pros and cons of their participation with trusted advisers, including their health care providers and family members. The NIH website (clinicaltrials.gov) offers some good questions to consider while deciding whether to enroll in a clinical trial.