Efficacy, Safety, and Population Pharmacokinetics of MW032 Compared With Denosumab for Solid Tumor–Related Bone Metastases: A Randomized, Double-Blind, Phase 3 Equivalence Trial

IMPORTANCE: The bioequivalence of denosumab biosimilar has yet to be studied in a 53-week, multicenter, large-scale, and head-to-head trial. A clinically effective biosimilar may help increase access to denosumab in patients with solid tumor–related bone metastases. OBJECTIVES: To establish the biosimilarity of MW032 to denosumab in patients with solid tumor–related bone metastases based on a large-scale head-to-head study. DESIGN, SETTING, AND PARTICIPANTS: In this 53-week, randomized, double-blind, phase 3 equivalence trial, patients with solid tumors with bone metastasis were recruited from 46 clinical sites in China. Overall, 856 patients were screened and 708 eligible patients were randomly allocated to receive either MW032 or denosumab. INTERVENTIONS: Patients were randomly assigned (1:1) to receive MW032 or reference denosumab subcutaneously every 4 weeks until week 49. MAIN OUTCOMES AND MEASURES: The primary end point was percentage change from baseline to week 13 of natural logarithmic transformed urinary N-telopeptide/creatinine ratio (uNTx/uCr). RESULTS: Among the 701 evaluable patients (350 in the MW032 group and 351 in the denosumab group), the mean (range) age was 56.1 (22.0-86.0) years and 460 patients were women (65.6%). The mean change of uNTx/uCr from baseline to week 13 was −72.0% (95% CI, −73.5% to −70.4%) in the MW032 group and −72.7% (95% CI, −74.2% to −71.2%) in the denosumab group. These percent changes corresponded to mean logarithmic ratios of −1.27 and −1.30, or a difference of 0.02. The 90% CI for the difference (−0.04 to 0.09) was within the equivalence margin (−0.13 to 0.13); the mean changes of uNTx/uCr and bone-specific alkaline phosphatase (s-BALP) at each time point were also similar during 53 weeks. The differences of uNTx/uCr change were 0.015 (95% CI, −0.06 to 0.09), −0.02 (95% CI, −0.09 to 0.06), −0.05 (95% CI, −0.13 to 0.03) and 0.001 (95% CI, −0.10 to 0.10) at weeks 5, 25, 37, and 53, respectively. The differences of s-BALP change were −0.006 (95% CI, 0.06 to 0.05), 0.00 (95% CI, −0.07 to 0.07), −0.085 (95% CI, −0.18 to 0.01), −0.09 (95% CI, −0.20 to 0.02), and −0.13 (95% CI, −0.27 to 0.004) at weeks 5, 13, 25, 37 and 53, respectively. No significant differences were observed in the incidence of skeletal-related events (−1.4%; 95% CI, −5.8% to 3.0%) or time to first on-study skeletal-related events (unadjusted HR, 0.86; P = .53; multiplicity adjusted HR, 0.87; P = .55) in the 2 groups. CONCLUSIONS AND RELEVANCE: MW032 and denosumab were biosimilar in efficacy, population pharmacokinetics, and safety profile. Availability of denosumab biosimilars may broaden the access to denosumab and reduce the drug burden for patients with advanced tumors. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04812509