Abstract 4074: Permeability changes and effect of chemotherapy in brain adjacent to tumor in an experimental model of brain metastases of breast cancer

Abstract

Abstract Background: Brain metastases vasculature is compromised and more permeable than that of vasculature in normal brain. Unfortunately, little is known about vascular permeability changes in brain adjacent to tumor (BAT). It is critical to understand the potential changes as chemotherapy penetration and accumulation brain tumors positively correlate with breakdown of the brain vasculature. Herein, we evaluate quantitatively measure permeability, drug accumulation and cytotoxicity in normal brain that is adjacent (<500 microns) to a tumor. Methods: The subclone population of brain seeking metastatic breast cancer cells (MDA-MB-231Br) were injected into the left ventricle of female NuNu mice. Mice were given a chemotherapeutic regimen of vinorelbine (10mg/kg), erubilin (1.5mg/kg) or docetaxel (10mg/kg). Progression occurred until neurological compromise was noted, at which time animals were injected with texas red 625 Da(TR) and texas red dextran 3kDa (TRD). Dye concentrations (measuring passive permeability changes) were determined in lesions and the BAT using quantitative fluorescent microscopy. Chemotherapeutic induced cytotoxicity was observed by staining for activated astrocytes and DNA damage in neurons, glia and endothelia. Results: We observed permeability of TR is highly heterogeneous both within and between the tumors (normal brain Kin TR: 1.2 x10-5)with 2-40-fold increase in permeability over normal brain region. TR concentrations in BAT (100µm from tumor edge) is consistently 40% of the tumor but significantly higher than that of normal brain and TR permeability in BAT increased 1-2.5-fold over normal brain. The permeability of TRD in tumor increased 2.7- 8.4-fold over normal brain, whereas in BAT, the permeability increased 1-1.6-fold over normal brain. We also observed animals treated with chemotherapy showed activated astrocytes in BAT, along with some cellular death. In vehicle treated animals there were little activated astrocytes and little cell death in the BAT. Conclusions: Our data suggests that the tracer and drugs accumulate in regions around tumors in the brain which result in neurotoxic changes. Citation Format: Afroz Shareef Mohammad, Chris E. Adkins, Neal Shah, Rawaa Aljammal, Jessica Griffith, Paul R. Lockman. Permeability changes and effect of chemotherapy in brain adjacent to tumor in an experimental model of brain metastases of breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4074. doi:10.1158/1538-7445.AM2017-4074