Galectin-1 (Gal-1) expression as a prognostic factor in patients with newly diagnosed glioblastoma (GB) treated with Stupp regimen (GLIOCAT study).

e13526 Background: Gal-1 is a β-galactoside binding protein that plays an important role in cancer, promoting cell invasion, proliferation, migration, angiogenesis and evasion of the immune response. Gal-1 is involved in glioma progression and is related to tumor grade and poor clinical outcome. Gal-1 has been implicated in resistance to chemotherapy and as a potential mediator of resistance to anti-VEGF therapy. The aim of our study was to evaluate the prognostic significance of Gal-1 in a homogenous cohort of GB patients and to analyze its potential predictive value of response to bevacizumab at recurrence. Methods: A substudy of GLIOCAT, a multicenter study of newly diagnosed GB patients treated with standard Stupp regimen (previously reported). GLIOCAT enrolled 432 patients between 2005-2014. Tissue was available from 243 cases, from which a tissue microarray (TMA) was constructed. Gal-1 expression in tissue from initial surgery was analyzed by immunohistochemistry. Results were evaluated by three reviewers and quantified by H-score. Expression levels were correlated with clinical outcome, known GB prognostic factors and response to bevacizumab. Results: We defined a cut off for Gal-1 H-Score of >60 (cytoplasm) and >25 (nucleus). HighcytoplasmicGal-1 expression significantly correlated with worse OS and with a trend for shorter PFS. In the multivariate analysis KPS, age, MGMT methylation status and, extent of resection but not Gal-1 expression were independent prognostic factors for survival. Of 92 patients who received bevacizumab at recurrence, only 54 were included in the TMA, and only 1 had low Gal-1 expression. We couldn’t find any relationship with OS or PFS in this population. Conclusions: Gal-1 expression may represent a prognostic factor for GB patients treated with standard therapy. [Table: see text]