Phase 2 placebo-controlled, single-blind trial to evaluate the impact of oral ibandronate on bone mineral density in osteopenic breast cancer patients receiving adjuvant aromatase inhibitors: 5-year results of the single-centre BONADIUV trial

Aim We present the final results of the BONADIUV trial, a single-blind, randomised, placebo-controlled phase 2 study to evaluate the impact of ibandronate treatment on bone mineral density (BMD) in osteopenic women taking aromatase inhibitors (AI). Patients and methods Between 2011 and 2014, 171 osteopenic patients were randomised in a 1:1 ratio to receive either placebo or oral monthly ibandronate (150 mg). Treatment duration was 2 years, with 6-month evaluation. Primary end-point was the 2-year lumbar spine (LS) and total hip (TH) T-score mean differences as measure of BMD variation. Secondary analyses of survival outcomes have been performed at a 5-year median follow-up. ClinicalTrials.gov identifier NCT02616744. Results Median age of study population was 60.2 years (range 44–75). At the database cut-off time, the median follow-up was 63.3 months (range 2.7–87.3). No difference in terms of T-score was shown at baseline between arms both for TH (P = 0.61) and LS (P = 0.96). At 2-year follow up, the mean change was statistically significant in favour of ibandronate arm both at TH (P = 0.0002) and LS (P < 0.0001). No significant difference in terms of adverse events was observed between arms. At a median follow-up of 63.3 months (range 2.7–87.3), the overall survival (OS) rate was 97.5% in the placebo group and 93.0% in the ibandronate arm (P = 0.19). The invasive disease-free survival (iDFS) rates did not differ between groups (P = 0.42). Conclusions Ibandronate compared to placebo improved BMD change in osteopenic women treated with adjuvant AI. Five-year survival analyses showed no difference between arms in terms of OS and iDFS rates.