Successful management of denosumab discontinuation in a patient with primary pediatric osteoporosis

Treatment of a 13.5-year-old boy with severe primary osteoporosis and multiple vertebral deformities with denosumab (Dmab) 60 mg subcutaneously every 3 months for 30 months, resulted in significant clinical, radiologic and densitometric improvement. During the second year of treatment, 2 episodes of transient hypercalcemia, probably due to the effect of growth spurt on bone remodeling were resolved quickly without any additional therapy except for the discontinuation of calcium supplements. When transition to the adult Dmab treatment schedule (60 mg/6 months) was attempted, severe hypercalcemia occurred 4 months after the last denosumab injection that was resolved quickly with a new Dmab injection. At the completion of 3 years of treatment, transition to oral alendronate 70 mg/weekly could not prevent a new episode of hypercalcemia that required a new Dmab injection concurrently with continuation of alendronate treatment to normalize. In the following months, serum calcium concentrations remained normal with only alendronate treatment that was stopped after 1.5 years, followed by a period of about 2 years with no additional osteoporosis treatment. In this unique case of primary pediatric osteoporosis observed closely in adolescence with and without Dmab treatment for more than 7 years, concurrent administration of alendronate and denosumab, followed by alendronate monotherapy for another year prevented further hypercalcemic episodes and allowed discontinuation of all treatments while maintaining the acquired BMD gains without any regression of the regained normal shape of vertebral deformities.