The safety and efficacy of the concurrent use of radiopharmaceutical strontium-89 (Sr-89) chloride with zoledronic acid in standard anticancer therapy for breast cancer patients with painful multifocal bone metastases.

Our aim in this study was to examine the safety and efficacy of the concurrent use of the radiopharmaceutical strontium-89 (Sr-89) chloride with zoledronic acid in standard anticancer therapy for breast cancer patients with painful multifocal bone metastases. The study comprised 33 breast cancer patients with painful multifocal bone metastases detected by bone scintigraphy, computed tomography, or magnetic resonance imaging. All patients were treated with Sr-89 and zoledronic acid concurrently between October 2007 and September 2012 as part of a standard therapeutic regimen comprising chemotherapy, endocrine therapy, molecular targeting therapy, and targeted radiotherapy. Sr-89 was administered intravenously at 2 MBq/kg to a maximum of 141 MBq per person. Safety was evaluated according to myelotoxicity as measured by the Common Terminology Criteria for Adverse Events (v3.0). To assess treatment efficacy, we monitored changes in analgesic drug dosages. Furthermore, bremsstrahlung imaging after the administration of Sr-89 was utilized to examine the relationship between the accumulation of Sr-89 in metastatic sites and treatment efficacy. Based on the results, a total of 25 out of 33 patients (76%) reported bone pain relief, indicating a high efficacy of Sr-89 combined with zoledronic acid. In responsive cases, a strong uptake of Sr-89 was observed on bremsstrahlung imaging at the same sites indicated by 99mTc bone scintigraphy. Moreover, severe white blood cell decreased (> grade 3) was observed in only 1 patient (3%), and severe platelet count degreased (> grade 3) was observed in 2 patients (6%), adverse events were tolerable. In conclusion, the use of Sr-89 with zoledronic acid in breast cancer patients with painful bone metastases was safe and effective when administered concurrently with other standard therapies. In the future, the treatment with Sr-89 at the early stage should be considered, and a large-scale clinical study should be conducted. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C216. Citation Format: Kimito Yamada, Hiroshi Kaise, Seiichirou Komatsu, Fuyou Kimura, Mayuko Matsumura, Yukiko Nakamura, Mari Hosonaga, Takahiko Kawate, Kana Miyahara, Yuko Kawai, Ai Ueda, Saeko Teraoka, Mana Yoshimura, Norio Kohno. The safety and efficacy of the concurrent use of radiopharmaceutical strontium-89 (Sr-89) chloride with zoledronic acid in standard anticancer therapy for breast cancer patients with painful multifocal bone metastases. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C216.