A phase II trial evaluating the palliative benefit of second-line oral ibandronate in breast cancer patients with either a skeletal related event (SRE) or progressive bone metastases (BM) despite standard bisphosphonate (BP) therapy

Background Despite bisphosphonate treatment, most patients with metastatic breast cancer will have either progressive bone metastases or skeletal related events (SREs). We evaluated the impact of second-line ibandronate on pain control and markers of bone turnover in these patients. Methods Patients with either an SRE or bony progression while on clodronate or intravenous (IV) pamidronate were switched to oral ibandronate 50 mg daily for 12 weeks. Pain scores and urinary N-telopeptide were evaluated weekly for 4 weeks and at weeks 8 and 12. There was no change in systemic anti-cancer treatment in the month before or after commencing study treatment. Palliative response was defined as a >= two-unit reduction in the worst pain score. Patient preferences between IV and oral bisphosphonate therapy were assessed. Results Thirty women completed the study. By week 12, patients experienced a significant improvement in pain control (OR = 0.41; P = 0.028) with 12 of 26 (46.2%) evaluable patients achieving a palliative response. Of the 23 patients who had received first-line IV pamidronate, 20 of 23 (87.0%) preferred oral therapy. Conclusion Patients with either progressive bone metastases or SREs while on clodronate or pamidronate may experience significant pain palliation with a switch to a more potent bisphosphonate. If confirmed by randomized trials, clinicians can start moving away from the paradigm whereby patients remain on a single bisphosphonate regimen throughout the course of their disease.