(021) Bone Modifying Agent Duration in Skeletal Related Events Prevention

Poster Abstract: BACKGROUND Cancer patients with bone metastases are at increased risk for skeletal related events (SREs), especially those with breast cancer, multiple myeloma, or prostate cancer. Skeletal related events are commonly defined as at least one of the following: pathologic fracture (excluding trauma), radiation therapy to bone, surgery to bone, or spinal cord compression. These events are correlated with worse clinical outcomes and a decrease in quality of life for patients. There are two agents that are typically utilized to prevent skeletal related events: denosumab and zoledronic acid. However, the duration of use for these agents has been limited to five years and two years for denosumab and zoledronic acid, respectively, and there is limited data regarding the benefit of extended therapy.

OBJECTIVE The purpose of this retrospective chart review is to determine if the duration of treatment with either denosumab or zoledronic acid is correlated with the incidence of skeletal related events.

METHODS This study was completed as a single-center, retrospective chart review completed at an academic medical center and its affiliated clinics. Patients aged 18 years or older diagnosed with either: metastatic breast cancer with at osseous metastases, metastatic castrate-resistant prostate cancer with osseous involvement, or multiple myeloma with osseous lesions, and had received at least one dose of denosumab or zoledronic acid were included in the study. Patients were stratified based on their malignancy type and which agent they received. The primary outcome was the incidence of skeletal related events. Secondary outcomes include the incidence of hypocalcemia, renal dysfunction, and osteonecrosis of the jaw.

RESULTS Results will be presented with poster at HOPA 2024 Annual Conference.

DISCUSSION/CONCLUSION Discussion and Conclusion will be presented with poster at HOPA 2024 Annual Conference.

References (must also be included in final poster): Fizazi K, Carducci M, Smith M, et al. Denosumab versus zoledronic acid for treatment of bone metastases in men with castration-resistant prostate cancer: a randomised, double-blind study. Lancet 2011; 377:813. ​

Himelstein AL, Foster JC, Khatcheressian JL, et al. Effect of Longer-Interval vs Standard Dosing of Zoledronic Acid on Skeletal Events in Patients With Bone Metastases: A Randomized Clinical Trial. JAMA 2017; 317:48. ​

Stopeck AT, Lipton A, Body JJ, et al. Denosumab compared with zoledronic acid for the treatment of bone metastases in patients with advanced breast cancer: a randomized, double-blind study. J Clin Oncol 2010; 28:5132. ​

Tu MM, Clemons M, Stober C, et al. Cost-Effectiveness Analysis of 12-Versus 4-Weekly Administration of Bone-Targeted Agents in Patients with Bone Metastases from Breast and Castration-Resistant Prostate Cancer. Curr Oncol 2021; 28:1847.