Marc Wein, M.D., Ph.D
Romosozumab is a novel osteoporosis treatment agent that stimulates bone formation and inhibits bone resorption. Due to concerns for adverse cardiovascular effects, this medication is generally reserved for patients with severe osteoporosis despite multiple previous treatments. However, the influence of previous osteoporosis pharmacotherapy on romosozumab’s skeletal efficacy remains poorly studied, especially in real world clinical scenarios. In a prospective non-randomized study of 130 patients treated with romosozumab in Japan, the effects of romosozumab treatment on bone turnover markers and bone mineral density (BMD) was assessed based on previous treatment with either no osteoporosis medication, bisphosphonates, denosumab, or teriparatide. In general, treatment-naïve individuals experienced superior spine BMD and bone turnover marker gains versus patients who had previously received osteoporosis pharmacotherapy. Notably, prior treatment with the potent anti-resorptive agent denosumab was associated with suboptimal spine BMD response to romosozumab. These results highlight the potential impact of previous anti-resorptive treatment on romosozumab efficacy and indicate that careful consideration of treatment sequence is warranted when deciding amongst the multiple osteoporosis agents that are currently available.
Denosumab is a potent anti-resorptive osteoporosis agent that works by neutralizing RANKL, the key cytokine that drives osteoclast differentiation. While effective at suppressing bone resorption, increasing BMD, and preventing fragility fractures when administered every 6 months, rapid discontinuation of denosumab has been associated with an increased risk of vertebral compression fractures. In routine clinical practice, denosumab injection delays are common. However, risks of vertebral fractures associated with such injection delays remain unknown. In this study of a UK population-based cohort of 2,594 patients , a large electronic database was used to assess the relationship between denosumab dosing intervals (defined as ‘on time’, ‘short delay’, and ‘long delay’) and fractures in the 6 month window after the recommended treatment date. Compared with ‘on time’ denosumab treatment, individuals who received delayed denosumab injections showed an increased risk of interval vertebral fractures. Notably, the delay time was associated with fracture risk. This powerful study design further underscores the importance of timely (every 6 months) denosumab injections. Given current health care delivery challenges associated with the COVID-19 pandemic, these results should be considered when selecting initial osteoporosis treatment agents and in management of patients currently receiving denosumab.
Abaloparatide, a synthetic analog of parathyroid hormone related peptide (PTHrP) is a bone anabolic osteoporosis treatment agent. In the ACTIVE study, abaloparatide increased bone mineral density and reduced fracture risk compared to both placebo and teriparatide. Although abaloparatide is generally well-tolerated, non-serious adverse events have been reported such as dizziness and palpitations. PTHrP can act in a paracrine manner to cause vasodilation. Therefore, in this post hoc drug safety study , the effects of abaloparatide on blood pressure, pulse, and cardiovascular adverse events were assessed in detail in subjects from the ACTIVE study (one hour post treatment) plus an additional group of 55 subjects for more detailed hemodynamic assessment. Compared to placebo injection, both abaloparatide and teriparatide treatment caused mild and transient increases in pulse and decreases in systolic blood pressure. These mild hemodynamic changes were not associated with an increased risk of adverse cardiovascular events. In general, these data are reassuring and support the cardiac safety of PTH analogs for osteoporosis. However, the transient hemodynamic changes observed should be considered for patients with cardiovascular comorbidities or baseline problems with orthostasis.