Polyostotic Fibrous Dysplasia Clinical Trial
Official title:
A Randomized, Placebo-Controlled Trial of Alendronate in the Treatment of Polyostotic Fibrous Dysplasia and the McCune-Albright Syndrome
This study will evaluate the effectiveness of alendronate in treating the bone abnormality in
polyostotic fibrous dysplasia and McCune-Albright syndrome. In these diseases, areas of
normal bone are replaced with a fibrous growth similar to a scar. The weakened bone causes
pain and increases patients' risk of bone fractures and bone deformities. Alendronate belongs
to a class of drugs called "bisphosphonates," which are approved by the Food and Drug
Administration to treat bone weakening, deformity and pain in other medical conditions. It is
thought that bisphosphonates might work by slowing the activity of osteoclasts-cells that
break down bone.
Patients 12 years of age and older with polyostotic fibrous dysplasia or McCune-Albright
syndrome may be eligible for this 3-year study. Candidates must also be enrolled in NIDCR's
protocol 98-D-0145 (Screening and Natural History of Patients with Polyostotic Fibrous
Dysplasia and McCune-Albright Syndrome).
Participants will be randomly assigned to one of two treatment groups: they will take one
capsule a day of either alendronate or placebo (a look-alike capsule that has no active
ingredient). They will take the capsules for 6 months, stop for 6 months, then take them for
another 6 months and then go off them for 6 months. They will then remain off the drug or
placebo for an additional 12 months and complete the study with a final follow-up visit at 36
months. While taking alendronate or placebo, patients will also take calcium and vitamin D to
prevent secondary hyperparathyroidism-a side effect of alendronate in which the bone does not
release enough calcium.
Patients will come to NIH for a physical examination and blood and urine tests every 6 months
and for monitoring of their bone disease, vision, hearing, pain levels, functional
evaluation, and photographs every 12 months. Many of the monitoring procedures, including
imaging studies and biopsies, are performed for the screening protocol (98-D-0145) and will
not be duplicated for this study. During the study periods when patients are taking
alendronate or placebo, they will have blood samples drawn by their local physician once
every 3 months and sent to NIH to check for secondary hyperparathyroidism.
If at the end of the study alendronate is found to be effective, patients who were in the
placebo treatment group will be offered alendronate for a 24-month period.
Polyostotic fibrous dysplasia (PFD) is a sporadic disorder which affects multiple sites in
the skeleton. The bone at these sites is rapidly resorbed and replaced by abnormal fibrous
tissue and mechanically abnormal bone. PFD may occur alone or as part of the McCune-Albright
Syndrome (MAS), a syndrome originally defined by the triad of PFD, cafe-au-lait pigmentation
of the skin, and precocious puberty. The bony lesions are frequently disfiguring and painful,
and depending on the location of the lesion, they can cause significant morbidity. Lesions in
weight-bearing bones can lead to disabling fractures, while lesions in the skull can lead to
compression of vital structures such as cranial nerves.
Currently there are no clearly-defined systemic therapies for this bone disease. Small,
uncontrolled trials using the second generation bisphosphonate, pamidronate, suggest that
bisphosphonates may be effective. This study is a phase 2, controlled, double blinded trial
of the third generation oral bisphosphonate, alendronate for the treatment of fibrous
dysplasia. We propose to show that treatment with alendronate will improve bone quality,
decrease bone pain, decrease fractures, and, if the patient is referred to the companion bone
grafting protocol, will allow for the regeneration of better quality bone.
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