Romosozumab as a First-Line Therapy

The Pharmaceutical Benefits Scheme (PBS) listing for romosozumab has been expanded to the treatment of severe established osteoporosis as a first-line therapy.

Romosozumab is a monoclonal antibody that inhibits sclerostin, an osteocyte-derived protein that can suppress bone formation. Remosozumab therapy increases bone formation as well as reducing bone resorption. This dual action results in increased bone mass and improved bone structure and strength.

The ARCH study found that 12 months of romosozumab treatment followed by alendronate was superior to alendronate alone in reducing fracture risk in postmenopausal women at high risk. The BRIDGE study demonstrated efficacy in men, with romosozumab associated with increased bone mineral density (BMD) at the hip and spine compared to placebo.

The usual dose of romosozumab is 210mg subcutaneously once a month for 12 doses. Patients should begin antiresorptive therapy (e.g., bisphosphonate or denosumab) once the romosozumab course is complete to preserve bone mass. Hypocalcaemia is an uncommon adverse event but may be more likely in patients with severe renal impairment. Adequate intake of calcium and vitamin D is important. Some studies suggest that romosozumab is associated with an increased risk of major cardiovascular adverse events. While additional real-world data is required, a recent meta-analysis did not find a significant increase in risk compared to placebo. Previous myocardial infarction or stroke are listed as contraindications in the product information.