# Impact of romosozumab treatment for 24 months after switching from denosumab: three case reports

## TL;DR

This study examines bone density changes in three osteoporosis patients who switched from denosumab to romosozumab for 24 months.

## Contribution

The study is the first to report on 24-month romosozumab treatment outcomes in patients previously treated with denosumab.

## Key findings

- Bone mineral density (BMD) showed variable improvements after 24 months of romosozumab in patients previously treated with denosumab.
- Bone turnover markers like P1NP and CTX peaked early and then declined in some patients but increased in others.
- Results suggest that romosozumab may have mixed effects on BMD and bone turnover in patients with prior denosumab exposure.

## Abstract

Prior denosumab use in osteoporosis patients diminishes the BMD gains from a subsequent 12-mo romosozumab regimen. However, few studies have explored BMD gains after 24 mo of romosozumab therapy. BMD at the LS-BMD, FN-BMD, and TH-BMD and P1NP and C-terminal telopeptide of type I collagen (CTX) levels were measured after 24 mo of romosozumab therapy in 3 osteoporosis cases with prior denosumab use. The changes in cases 1-3 at 12 and 24 mo, respectively, were as follows: LS-BMD (−2.9% and 7.4%, 0.9% and 7.9%, 7.2% and 7.9%), FN-BMD (3.2% and 7.1%, −1.2% and 2.0%, 2.7% and 2.1%), and TH-BMD (−1.2% and 6.7%, −4.9% and −0.3%, −0.3% and 3.2%). The P1NP and CTX levels in case 1 (18.80 ng/mL, 0.042 ng/mL) peaked at 6 mo (185.00 ng/mL, 1.280 ng/mL) and then decreased at 24 mo by 60.8% and 65.3%, respectively. The P1NP and CTX levels in case 2 (17.10 ng/mL, 0.059 ng/mL) peaked at 12 mo (132.00 ng/mL, 1.190 ng/mL) and then decreased at 24 mo by 65.3% and 24.3%, respectively. In case 3, the P1NP and CTX levels (56.10 ng/mL, 0.490 ng/mL) increased at 24 mo by 233.3% and 375.5%, respectively. This is the first report of a 24-mo romosozumab regimen in a small group of osteoporosis patients with prior denosumab use having varied effects on BMD and bone turnover. Nonetheless, larger controlled studies are needed to confirm these findings.