Abstract 2984: Normalization of tumor vasculature by anti-angiogenesis therapy in metastatic tumor: A clinical study to determine the timing and effect

Abstract

Abstract Background: Clinically, combination of anti-angiogenic agents with chemotherapeutic agents demonstrated better antitumor efficacy. Instead of merely effect on vasculature regression, careful use of anti-angiogenic therapy may cause the grossly abnormal structure and function of tumor blood vessels to return to a more normal state. Treatment with anti-angiogenic agents can primarily improve chemotherapy efficacy by normalizing tumor vasculature, decrease the intra-tumor interstitial pressure, thereby leading to a more effective drug delivery. We planned to investigate the timing and effect of tumor vascular normalization in human after the administration of anti-angiogenic agent. It may help determine the appropriate timing of administration of chemotherapeutic agents after anti-angiogenic treatment. Materials and methods: This study enrolled the last 8 consecutive patients who participated in a phase II trial for treatment of refractory brain metastases from breast cancer (Eur J Can 49:2s, 2013 suppl; abstr 1878). The protocol treatment consists of bevacizumab 15mg/kg on day 1, chemotherapy of etoposide and cisplatin on day 2 (24 hours after administration of bevacizumab), in 21-day cycles. These 8 patients specifically received four dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) examinations. DCE-MRI was performed before treatment, 1 hour after the end of bevacizumab infusion (i.e., 2.5 hours after starting bevacizumab infusion), 24 hours and 21 days after bevacizumab infusion. This study was registered with ClinicalTrials.gov, identifier NCT01281696, and was approved by the ethical review board. Results: Clinically, all the 8 patients achieved partial remission at central nervous system. All of the 4 DCE-MRI parameters decreased after bevacizumab infusion. Compared to baseline values, the mean reductions at 1 hour and 24 hours were -12.8% and -24.7% for Peak, -46.6% and -65.8% for Slope, -27.9% and -55.5% for iAUC60, -46.6% and -63.9% for Ktrans, respectively (all P values <0.05). The differences between 1 hour and 24 hours reached statistical significance (all P values <0.05) for all the parameters. However, the differences in the mean percentage change between 24 hours and 21 days did not reach significance in any of the four parameters Conclusion: Normalization of tumor vasculature induced by bevacizumab was clearly demonstrated in brain metastases in human at 1 hour after completion of bevacizumab infusion, but significantly became more obvious at 24 hours after bevacizumab administration. Citation Format: Yen-Shen Lu, Bang-Bin Chen, Ching-Hung Lin, Wei-Wu Chen, Pei-Fang Wu, Ann-Lii Cheng, Tiffany Ting-Fang Shih. Normalization of tumor vasculature by anti-angiogenesis therapy in metastatic tumor: A clinical study to determine the timing and effect. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2984. doi:10.1158/1538-7445.AM2014-2984