A randomized trial of denosumab (AMG 162) versus intravenous (IV) bisphosphonates (BP) in cancer patients (pts) with bone metastases (BM) on established IV BP and evidence of elevated bone resorption

Abstract

8562 Background: Pts on established (≥ 8 weeks) IV BP who have elevated bone resorption markers, especially urinary N-telopeptide (uNTx), are at increased risk for skeletal related events (Coleman, J Clin Oncol 2005). Denosumab, a fully human monoclonal antibody, inhibits osteoclastic bone resorption by binding and neutralizing RANK ligand, a key mediator of osteoclast differentiation and function. Denosumab efficacy and safety were evaluated in a phase 2, randomized, open label, active-controlled study in advanced cancer pts with BM and elevated levels of uNTX despite established IV BP therapy. We report preliminary results from an interim analysis of 49 pts at week 13. Methods: Eligible pts (≥18 yrs old with solid tumor [except lung] or multiple myeloma [MM]; confirmed BM; screening uNTx > 50 nM BCE/mM creatinine [Cr]; on IV BP for ≥ 8 weeks before randomization) are stratified by baseline uNTx (50–100, >100) and tumor type. Pts are randomized to 1 of 3 arms: IV BP every 4 weeks (Q4W) or 180 mg denosumab given subcutaneously Q4W or Q12W. The primary endpoint is the proportion (%) of pts with uNTx < 50 nM BCE/mM Cr at week 13. Enrollment is ongoing (planned N = 135). Results: The mean (range) age of all pts in the analysis (33 denosumab; 16 BP) was 62.5 (39, 81) yrs; 96% had > 2 BM. The median time on prior IV BP (mostly zoledronic acid) was 5.1 months. Tumors included prostate (n = 24), breast (n = 20), other/MM (n = 5). The % of pts with uNTx < 50 nM BCE/mM Cr at week 13 was greater with denosumab (pooled arms) than IV BP: 76% (95% CI: 60.3, 91.2) vs 38% (95% CI: 18.5, 61.4; P = .015 Cochran-Mantel-Haenzel), respectively. No treatment-related serious adverse events (SAEs) were reported. Commonly reported AEs in the denosumab arms included nausea, peripheral edema, anemia, bone pain, and constipation. At data cutoff, 10 deaths (6/33 denosumab, 4/16 BP) had occurred on-study. Conclusions: These interim data suggest that denosumab normalizes uNTx more frequently than IV BP in pts with elevated uNTx despite 8 weeks of IV BP, across all tumor types. The AE profile of denosumab appeared similar to that of cancer pts undergoing treatment. [Table: see text]