Denosumab boosted bone mineral density (BMD) over 12 months to a greater extent than did alendronate in a randomized, 12-month study. The investigator-initiated research compared BMD at the lumbar spine and elsewhere among people with systemic lupus erythematosus (SLE) and other autoimmune conditions. Long-term glucocorticoid therapy places some people in this group at higher risk for adverse effects of bone density loss.
Dr. Gregg Silverman
“Glucocorticoids remain the mainstay of treatment of rheumatic diseases, but [they are] a major risk factor for osteoporosis and fracture,” study author Chi Chiu Mok, MD, said in an interview.
Compared with baseline, adults randomly assigned to denosumab had a 3.5% increase in lumbar spine BMD at 12 months, compared with 2.5% among those taking alendronate, a significant difference. Dr. Mok, a consultant and honorary associate professor in the department of medicine and nuclear medicine at Tuen Mun Hospital in Hong Kong, presented the study results at the virtual annual meeting of the American College of Rheumatology.
“Given the knowledge that denosumab is more effective than alendronate in raising spinal BMD in chronic users of GCs without increasing adverse events, this drug may be considered as an alternative first-line therapy in higher-risk patients and in those who are contraindicated for the oral bisphosphonates,” he said.
Cost considerations
Denosumab is a human monoclonal antibody administered as a subcutaneous injection, available under the brand names Prolia and Xgeva. Alendronate is an oral agent available as both generic and brand name formulations.
“Yes, denosumab is more expensive, more costly than oral alendronate, but our study shows efficacy is better for steroid users,” Dr. Mok said in answer to a question about cost disparity between the two agents during his presentation at the meeting. “For patients who are contraindicated or have low compliance for bisphosphonate, or are high-risk patients, I recommend first-line use of denosumab.”
Researchers previously studied these agents, including a smaller study by Dr. Mok and colleagues that showed a BMD benefit after switching people on an oral bisphosphonate to denosumab. However, he said, “There is a paucity of data regarding comparative efficacy of denosumab and the bisphosphonates in long-term steroid users.”
To explore any differences in a larger patient population, the investigators randomly assigned adults with SLE and other autoimmune conditions to the two treatments: denosumab 60 mg subcutaneoulsy every 6 months or oral alendronate 70 mg/week. All patients also received 3,000 mg calcium and 1,000 IU vitamin D3 (cholecalciferol) each day.
After three discontinuations in denosumab cohort and four in the alendronate group, the researchers evaluated 69 people taking denosumab and 70 others taking alendronate. The discontinuations were caused by noncompliance, Dr. Mok said, not by adverse events.
Adverse events were reported, but the rate did not differ significantly between groups. Dr. Mok highlighted some notable differences, including more minor infections and arthralgias reported in the denosumab cohort. Chest discomfort was reported in one denosumab recipient versus no patients in the alendronate group. Dyspepsia/upper GI symptoms and dizziness/vertigo occurred more often in the alendronate group.
Women were 96% of the study population, and mean age was 50 years. A majority, 81%, had underlying SLE. Other diagnoses included rheumatoid arthritis, myositis, antineutrophil cytoplasmic antibody–associated vasculitis, and polymyalgia rheumatica. The mean dose of prednisolone at study entry was 5.1 mg/day.