Repair of Bone Erosion in Rheumatoid Arthritis by Denosumab: A High-Resolution Peripheral Quantitative Computed Tomography Study

Objective: To compare the bone healing effects of denosumab and alendronate in female rheumatoid arthritis (RA) patients by high-resolution peripheral quantitative computed tomography. Methods: This is a post hoc analysis of a randomized controlled trial. Forty patients were randomized in a 1:1 ratio to receive either subcutaneous denosumab (60 mg) once or oral alendronate (70 mg) weekly for 6 months. The size of individual bone erosions and the presence and extent of erosion-associated sclerosis (marginal osteosclerosis) were measured in the second metacarpal head of the nondominant hand at baseline, 3 months, and 6 months. Results: Forty-two erosions were identified at baseline. After 6 months, the width, depth, and volume of erosion significantly decreased in the denosumab group (−0.23 mm, −0.16 mm, −0.91 mm³, respectively; all P < 0.01), whereas these parameters significantly increased in the alendronate group (0.19 mm, 0.32 mm, and 1.38 mm³, respectively; all P < 0.01; between-group differences, P < 0.01 for all). Quantitative analysis showed that the bone mineral density of the erosion margin significantly increased only after treatment by denosumab (19.75 mg/cm³; P < 0.05 for denosumab, and −5.44 mg/cm³; P = 0.51 for alendronate; P < 0.05 for between-group differences). Conclusion: Inhibition of receptor activator of NF-κB ligand by denosumab can induce partial repair of erosions in patients with RA, while erosions continued to progress in patients treated with alendronate. Combining denosumab with disease-modifying antirheumatic drugs may be considered for RA patients with progressive bone erosions.