Women with osteoporosis who received a single infusion of zoledronate after discontinuing denosumab (Prolia) maintained bone mineral density at both the lumbar spine and the total hip, based on data from 120 individuals.
Although denosumab is often prescribed for postmenopausal osteoporosis, its effects disappear when treatment ends, wrote Judith Everts-Graber, MD, of OsteoRheuma Bern (Switzerland), and colleagues. In addition, recent reports of increased fractures in osteoporotic women after denosumab discontinuation highlight the need for subsequent therapy, but no protocol has been established.
In a study published in the Journal of Bone and Mineral Research, the investigators reviewed data from women aged older than 48 years with postmenopausal osteoporosis who were treated with denosumab between Aug. 1, 2010, and March 31, 2019. The women received four or more injections of 60 mg denosumab administered at 6-month intervals, followed by a single infusion of 5 mg zoledronate 6 months after the final denosumab injection. Patients were evaluated using dual-energy x-ray absorptiometry and vertebral fracture assessment every 2 years after starting denosumab; the average duration of treatment was 3 years.
At an average of 2.5 years after discontinuing denosumab, women who received zoledronate retained 66% of bone mineral density (BMD) gains at the lumbar spine, 49% at the total hip, and 57% at the femoral neck. In addition, three patients developed symptomatic single vertebral fractures and four patients developed peripheral fractures between 1 and 3 years after their last denosumab injections, but none of these patients sustained multiple fractures.
All bone loss occurred within 18 months of denosumab discontinuation, and no significant differences appeared between patients with gains in BMD greater than or less than 9%.
The study findings were limited by several factors, including the retrospective design and the lack of a control group, the researchers noted. However, they collected data from 11 of 28 patients who did not follow the treatment recommendations and did not receive zoledronate after discontinuing denosumab. “As expected, BMD of the lumbar spine and total hip decreased to baseline,” they wrote. In addition, 2 of the 11 patients experienced multiple vertebral fractures.
A single 5-mg infusion of zoledronate “may be a promising step in identifying sequential long-term treatment strategies for osteoporosis,” the researchers concluded. “Nevertheless, each patient requires an individualized surveillance and treatment plan after denosumab discontinuation, including BMD assessment, evaluation of bone turnover markers and consideration of individual clinical risk factors, in particular prevalent fragility fractures.”
The study was funded by OsteoRheuma Bern. The researchers reported having no financial conflicts.
SOURCE: Everts-Graber J et al. J Bone Miner Res. 2020 Jan 28. doi: 10.1002/jbmr.3962.