Two-year results of a randomised trial comparing 4- versus 12-weekly bone-targeted agent use in patients with bone metastases from breast or castration-resistant prostate cancer.

Abstract

BACKGROUND:

We present the 2-year results of a randomised trial comparing 4- versus 12-weekly bone-targeting agents (BTAs) in patients with bone metastases from breast or castration-resistant prostate cancer (CRPC).

PATIENTS AND METHODS:

Patients with bone metastases from breast or CRPC, who were going to start or were already receiving BTAs, were randomised to 4- or 12-weekly BTA treatment for 2 years. The endpoints were: symptomatic skeletal events (SSE) rates, time to SSEs, toxicity and cost-effectiveness.

RESULTS:

Of 263 patients (160 breast cancer, 103 CRPC), 133 (50.6%) and 130 (49.4%) were randomised to the 4- and 12-weekly groups, respectively. BTAs included denosumab (56.3%), zoledronate (24.0%) and pamidronate (19.8%). After 2 years, the cumulative incidence rate (95% CI) of SSEs was 32.7% (24.6% to 41.1%) and 28.1% (20.3% to 36.4%) for the 4- and 12-weekly intervention groups respectively. The hazard ratio for time to first SSE was 0.96 (95% CI = 0.63 to 1.47). However, in a post hoc analysis, those patients who had an on-study SSE, there was a small non-statistical increased risk of subsequent SSEs among patients on the 12-weekly dosing arm (HR = 1.14; 95% CI - 0.90-1.44). BTA-related toxicity rates were similar between study arms. A cost-utility analysis showed that 12-weekly BTA is cost-effective from a public payer's perspective.

CONCLUSION:

These results in addition to those previously reported for de-escalating zoledronate, would support that de-escalation of commonly used BTAs is a reasonable and economically valid treatment option. While not statistically significant, the increase in subsequent SSEs in the 12-weekly arm requires further exploration.

• Authors: Mark Clemons, Michelle Liu, Carol Stober, Gregory Pond, Mashari Jemaan Alzahrani, Michael Ong, Scott Ernst, Christopher Booth, Mihaela Mates, Anil Abraham Joy, Olexiy Aseyev, Phillip Blanchette, Lisa Vandermeer, Megan Tu, Kednapa Thavorn, Dean Fergusson, REaCT investigators
• Journal: Journal of bone oncology (J Bone Oncol) Vol. 30 Pg. 100388 (Oct 2021) ISSN: 2212-1366 [Print] Netherlands
• PMID: 34567960 (Publication Type: Journal Article)
• Copyright: © 2021 Published by Elsevier GmbH.