# Effectiveness of romosozumab following prior raloxifene treatment in primary osteoporosis: An observational study

## TL;DR

This study found that romosozumab is effective and safe for treating osteoporosis in women who previously took raloxifene.

## Contribution

The study provides new evidence on the effectiveness of romosozumab after prior raloxifene treatment in osteoporosis.

## Key findings

- Romosozumab increased bone mineral density in both treatment-naïve and raloxifene-treated groups.
- No new fractures occurred in either group during the 12-month study period.
- Prior raloxifene treatment did not significantly affect bone turnover markers or BMD changes with romosozumab.

## Abstract

Romosozumab is an anti-sclerostin antibody that increases bone formation and decreases bone resorption. It has been available for patients at high risk of osteoporotic fractures in Japan since 2019. The aim of this study was to clarify the clinical effectiveness and safety of romosozumab following previous treatment with raloxifene. The study had an observational pre–post design and included 62 women with primary osteoporosis. Romosozumab 210 mg was administered subcutaneously every 4 weeks for 12 months in patients who had been previously treated with raloxifene (raloxifene group, n = 12) and in those who were treatment-naïve (treatment-naïve group, n = 50). The incidence of new fractures, safety, and changes in bone mineral density (BMD) and bone turnover markers (BTMs) were recorded. No new fractures occurred in either group. Ten patients (16.1%) in the treatment-naïve group discontinued romosozumab for the following reasons: non-serious adverse events (n = 2, 3.2%), a change to another hospital (n = 1, 1.6%), self-discontinuation (n = 5, 8.1%), and financial constraints (n = 2, 3.2%). The percent changes in spine BMD and total hip BMD at 12 months were respectively +13.5% and + 4.9% in the treatment-naïve group and + 16.0% and + 3.4%, respectively, in the raloxifene group. We did not detect significant differences in the changes in BTMs according to whether there was previous treatment with raloxifene. Prior raloxifene treatment may be well tolerated and may not affect increases in BMD, changes in BTMs, and fracture prevention in romosozumab therapy.

•BMD gains may not be attenuated in romosozumab therapy following prior raloxifene.•BTMs may not change according to whether there was prior raloxifene treatment.•Romosozumab following raloxifene may be safe in primary osteoporosis.•The new fracture rate may be very low in romosozumab therapy after raloxifene.

BMD gains may not be attenuated in romosozumab therapy following prior raloxifene.

BTMs may not change according to whether there was prior raloxifene treatment.

Romosozumab following raloxifene may be safe in primary osteoporosis.

The new fracture rate may be very low in romosozumab therapy after raloxifene.