PP117 Factors associated with improved survival and BDNF-TrkB expression using multiplex immunohistochemistry in breast cancer brain metastasis

Brain metastasis (BM) in breast cancer is a devastating condition, yet little known about features unique to the brain environment. When develops ER-positive cancer, endocrine therapy can still work as main treatment. Several pieces of research have concluded on estrogen effect and activity toward BM. The purpose this study was find prognostic factors treatment strategies that could extend brain-specific survival. We examined BDNF-induced TrkB pathway activation analyze estrogen-related effects environment metastatic tumor cells. A retrospective 115 patients from Jan 2006 Dec 2018 at Seoul St Mary’s hospital with BM done. compared PFS, OS by characters Twenty-two samples were further analyzed. Multiple immunohistochemistry BDNF, TrkB, phospho-AKT staining performed. median age diagnosis 51. TNBC, HER2-positive, luminal A, B subtypes 19.6, 21.4, 13.9, 43.5 percent, respectively. Seventeen percent had leptomeningeal involvement. Eighty-seven treated radiation and/or surgery. Endocrine independently related prolonged (HR for PFS OS, 0.22 0.19; 95% confidence interval, 0.08-0.58 0.08-0.46; P=0.002 P<0.001). Localized associated better OS. Leptomeningeal involve (11 vs 2 months, P=0.013), multiple lesions (20 10 5 P=0.002) shorter In pathological analysis 22 patients, BDNF expression tended be higher (P=0.051), similar (P=0.153). Tumoral BDNF-TrkB-phosphoAKT coexpression (Spearman rho 0.514, P=0.014) ERa (Rho 0.544, P=0.009) showed positive correlations. contrast, HER2 negative correlation -0.534, P=0.010). Stromal low. status (57.8 27.1%, P=0.009). survival affected application local treatments nature tumors. For BCBM, beneficial control. saw possibility depletion inhibition endocrine-dependent BDNF/TrkB would achieve anti-tumor activity. Further investigation mechanism warranted.