BTC1.07 Brain metastases: immune characterization and the impact over prognosis

Abstract

BACKGROUND: Brain metastases (BrMets) are one of the most frequent and devastating neurological complications related to systemic cancer, thus representing a significant cause of morbidity and mortality. They are the commonest intracranial tumours, surpassing primary brain tumours. Most brain metastases originate from lung cancer (36-64%), breast cancer (15-25%) and melanoma (5-20%), and account for 67%-80% of all cancers. Few studies of human CNS metastases are available because only a small percentage of affected patients undergo surgery. The activation of immune cells by targeting check point inhibitors showed promising results e several primary tumors but the use in brain metastases special type of metastization considering the brain nich and its particular sanctuary characteristics is to be better underst and MATERIAL AND METHODS: In vivo studies: we used a retrospective cohort of 30 patients diagnosed with breast cancer and brain metastases, who underwent excision of BCBM in Hospital de Santa Maria - CHLN and adjuvant treatment as clinical indicated. The cohort includes complete demographic, clinicopathologic, and clinical outcome data extracted from medical records to explore the classical survival endpoints. The expression of estrogen receptor alpha (ERα), progesterone receptor (PR) and HER2 was determined by immunohistochemistry (IHC) in the metastatic tissue and with the primary tumours. The expression of CD4+, CD8+(TIL'sTumour Inflitrating Lymphocites), PD-L1, glial ibrillary acid protein (GFAP) was also be performed by IHC in the brain metastases. 2. In vitro experiments: The breast cancer brain tropic cell line (MDA-MB-231 BR Her 2+ and Her2-) was cultured to determine the expression of ERα, PR, HER2, PD-1, PD-L1 and by RT-qPCR. RESULTS: In our Cohort, reflecting the expected prevalence of breast cancer subtypes prevalence, Nor the PDL 1 nor GFAP or Til's status were biomarkers of prognosis although the in vitro studies for brain tropic cells point to distinct significant expressions according to tropism/subtype. CONCLUSION: Breast cancer doesn't seem to assume an immunogenic behavior when brain metastases are well-established though the process to tropism may assume a step where immunogenecity cross talk between cells and stroma may be different considering brain nich.