In Vivo Simvastatin and Brain Radiation in a Model of HER2+ Inflammatory Breast Cancer Brain Metastasis

Abstract

PurposeInhibiting HMG-CoA reductase with simvastatin prevents breast cancer metastases in preclinical models and radiosensitizes monolayer and stem-like IBC cell lines in vitro. Given the extensive use of simvastatin worldwide and its expected penetration into the brain, we examined whether regulating cholesterol with simvastatin affected IBC3 HER2+ brain metastases. Methods and MaterialsBreast cancer cell lines KPL4 and MDA-IBC3 were examined in vitro for DNA repair after radiation with or without statin treatment. Brain metastasis endpoints were examined in the MDA-IBC3 brain metastasis model after ex vivo exposure to lipoproteins and after tail vein injections with and without whole-brain radiotherapy (WBR) and oral statin exposure. ResultsEx vivo preculture of MDA-IBC3 cells with very low-density lipoprotein (vLDL) enhanced the growth of colonized lesions in the brain in vivo compared with control or high-density lipoprotein (HDL), and concurrent oral simvastatin/ WBR reduced the incidence of micrometastatic lesions evaluated 10 days after WBR. However, statin, with or without WBR, did not reduce the incidence, burden, or number of macrometastatic brain lesions evaluated 5 weeks after WBR. ConclusionsAlthough a role for cholesterol biosynthesis is demonstrated in DNA repair and response to whole brain radiation in this model, durable in vivo efficacy of concurrent whole brain irradiation and oral statin was not demonstrated.