The case was reported in the journal Therapeutics and Clinical Risk Management, in an article titled “Efficacy of Denosumab Therapy for a 21-Year-Old Woman with Prader-Willi Syndrome, Osteoporosis and History of Fractures: a Case Report.”
Probably as a result of growth and sex hormone deficiencies, hypotonia (low muscle tone), and physical inactivity, many people with PWS develop osteoporosis (low bone mineral density, BMD), a condition that increases the risk of fractures.
Replacement therapy with growth hormone (GH) and sex hormones can help improve BMD in young PWS patients. However, GH may be ineffective in adult PWS patients, and some individuals may continue having low BMD despite receiving hormonal therapy.
Biphosphonates (such as alendronate, ibandronate, risedronate, and zoledronic acid) are commonly used for the treatment of osteoporosis. However, the use of these medications in adolescents and young adults remains controversial and, as with hormonal replacement, some patients do not respond to the treatment.
The case report describes the story of a 21-year-old woman with PWS, very low BMD, and a history of fractures, despite being treated with growth hormone between ages 7-14, and with estrogen from age 15.
The patient was treated with three subcutaneous (under-the-skin) injections of denosumab every six months (at 0, 6, and 12 months). Denosumab is a human monoclonal antibody approved for the treatment of osteoporosis that works by inhibiting the formation of osteoclasts — cells that break down bone tissue.
To assess denosumab’s effectiveness, BMD and bone turnover markers were measured before and after 4, 8, and 13 months of treatment. BMD was assessed in the hip region through a specialized form of X-ray technology called dual-energy X-ray absorptiometry. Bone turnover markers allow the assessment of bone formation and resorption.
After 13 months of denosumab treatment, the patient’s BMD increased by 4.5%, and bone turnover markers notably improved. No fractures or adverse effects occurred.
“To our knowledge, this study is the first of its kind describing the successful use of osteoporotic treatment denosumab for a patient with PWS and a history of fractures,” the researchers said.
Although the team acknowledged that this is a single case report, they suggested that “denosumab could represent an effective treatment option for osteoporosis in PWS patients.”