Impact of standard versus cyclic teriparatide and denosumab treatment on trabecular bone score: a post-hoc analysis of a randomized clinical trial.

UNLABELLED: The osteoanabolic effects of teriparatide are maximal in the first 6 months of treatment. This secondary analysis of a randomized clinical trial investigated whether cyclic teriparatide would improve Trabecular Bone Score (TBS) more than standard dosing over 36 months. Results showed similar improvements in TBS with both teriparatide regimens.

INTRODUCTION

The effects of teriparatide (TPTD) are maximal in the first 6 months when bone formation exceeds resorption to the greatest degree. Cyclic use of TPTD was proposed to try to broaden this anabolic window. Prior results from this study showed that 6-month cycles of TPTD and denosumab did not improve BMD compared to standard dosing with TPTD followed by denosumab. The goal of this study was to determine if there was any difference in trabecular bone score improvement (TBS) with cyclic vs standard therapy.

METHODS

70 postmenopausal women with osteoporosis were randomized to TPTD for 18 months followed by denosumab for 18 months (standard; n = 32) or three cycles of 6 months TPTD, each followed by denosumab (cyclic; n = 32). DXA measurements of the lumbar spine (LS) were performed every 6 months and TBS calculated at baseline, 18 and 36 months on the 50 participants who completed the 36-month final study visit. This paper is a post-hoc analysis of a prior clinical trial looking at BMD change at 36 months for cyclic vs. standard dosing.

RESULTS

At baseline, TBS was similar between the 2 groups with mean level 1.24 ± 0.05, considered partially degraded. In the standard group, TBS increased by 1.1% at 18 months (p = 0.11 vs baseline) and 1.6% at 36 months (p < 0.11 vs baseline). In the cyclic group, TBS increased by 2.4% and 2.6% at 18 and 36 months from baseline, respectively (both p < 0.05 vs. baseline). However, there were no group differences in TBS increments at either 18 or 36 months. At 36 months, 17 total participants had improvement in their TBS category from either degraded to partially degraded or partially degraded to normal, or degraded to normal with 4 deteriorations to a lower category. There was no difference between groups in the TBS category change.

CONCLUSION

TBS improved similarly with cyclic and standard treatment regimens of TPTD and denosumab over 36 months, however possible differences may have been masked by inadequate study power.