3089 Clinicopathologic and Prognostic Significance of LGR5, a Cancer Stem cell Marker in Peritoneal Metastasis of a Colorectal Origin

OBJECTIVES/SPECIFIC AIMS: Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) is expressed on Wnt/β-catenin-dependent adult stem cell populations of the colon. Cancer stem cells are hypothesized to be the driving force behind tumor progression and metastasis, making them attractive therapeutic targets. Our aim was to analyze the clinicopathologic and prognostic significance of LGR5 expression in a cohort of colorectal cancer patients with peritoneal metastasis. METHODS/STUDY POPULATION: A total of 49 Formalin-fixed paraffin-embedded (FFPE) tissue blocks of primary or metastatic tumors and their respective normal tissues were collected from the tissue bank for time period 2009-2015. LGR5 expression was assessed at the protein level through immunohistochemical (IHC) staining of tissue microarray (TMA) constructs consisting of pairs of tumor and normal colon tissue. The correlation between LGR5 expression and clinicopathologic parameters and prognosis was assessed by statistical analysis. RESULTS/ANTICIPATED RESULTS: Of the 49 patient sample, 30(61.22%) were female vs. 19 (38.78%) males. Age range at initial diagnosis ranged from 31.7 years to 84.4 years, with a median age of 61.29 years. Duration of follow-up ranged from 1 – 9 years with a median of 5 years.LGR5 expression was higher in colorectal cancer than in normal mucosa. In univariate survival analysis overexpression of LGR5 was significantly associated with improved survival (p=0.002).Of significance, LGR5 positivity was an independent prognostic marker for better prognosis in a multivariate survival analysis adjusting for prognostic variables age, stage, gender, tumor histology and grade (HR 2.67. 95% CI 1.01-7.00, P = 0.046). DISCUSSION/SIGNIFICANCE OF IMPACT: LGR5 was significantly over expressed in colorectal cancer compared to normal tissues. LGR5 was noted to be an independent prognostic variable for an improved survival outcome in colorectal cancer patients with peritoneal metastasis, making LGR5 a potential therapeutic target in colorectal cancer patients with peritoneal metastasis.