Efficacy of 4-year denosumab treatment alone or in combination with teriparatide in Japanese postmenopausal osteoporotic women

Purpose: This extended randomized prospective study aimed to compare the 4-year clinical outcomes of denosumab treatment alone or in combination with teriparatide in treatment-naïve postmenopausal Japanese patients with osteoporosis. Methods: Between July 2013 and December 2016, 30 eligible women from our previous study were enrolled. After newly adding 17 randomly assigned patients, 47 patients were classified into the denosumab alone group (denosumab group, n = 22) or denosumab plus teriparatide group (combination group, n = 25). Serum bone-specific alkaline phosphatase (BAP), serum tartrate-resistant acid phosphatase (TRACP)-5b, urinary cross-linked N-terminal telopeptide of type I collagen (NTX), and bone mineral density (BMD) of the lumbar 1-4 vertebrae (L-BMD) and bilateral total hips (H-BMD) were determined at the first visit and at regular time points up to 48 months of treatment to determine percentage changes. Results: BAP was significantly decreased from baseline in both groups from 24 to 48 months, with significant differences at all time points between the groups. TRACP-5b and urinary NTX were comparably decreased at every time point in both groups versus pretreatment levels. L-BMD was significantly more increased by combination therapy over denosumab alone at 24 and 30 months (21.1% increase vs. 14.2% increase at 48 months). There were no significant differences in H-BMD between the groups, although levels tended to be higher in the combination group throughout the study period (9.7% increase vs. 6.8% increase at 48 months). Conclusion: Long-term denosumab and teriparatide combination therapy represents an effective treatment option for primary osteoporosis patients with low L-BMD.