Abstract 1911: High MET and CA9 expressions define a subgroup of hepatocellular carcinoma (HCC) patients with poor prognosis candidates for MET inhibition strategy

Abstract

Abstract Background: In HCC, hypoxia and MET can promote tumor progression and induce resistance to radiation, chemo or targeted therapies. The aim of this study was to correlate MET and hypoxia marker carbonic anhydrase 9 (CA9) expression levels by immunohistochemistry with clinicopathological characteristics and disease-free survival (DFS) in patients with HCC. Material and methods: One-hundred HCC resection specimens were evaluated by immunohistochemistry for MET (clone sp44, Ventana) and CA9 (rabbit polyclonal) expression. For automated evaluation, we elaborated our own macro using ImageJ software, and compared it with H- and MetMab validated scores. METhigh and CA9high expression were defined as moderate to strong staining. Staining results were correlated with clinicopathological characteristics. Univariate analyses were performed using Fisher's exact or chi square tests, and multivariate analyses using Cox regression model. Median DFS (mDFS) were calculated by Kaplan-Meier method. MET amplification was assessed by FISH (zytovision probe) and centromere 7 (CEN7) used as an internal control. Amplification was defined as a mean ratio of MET/CEN7> 4, counting 100 nuclei. Results: Tumors were BCLC A1 (92%), uninodular (53%), moderately differentiated (63%), with pathological vascular invasion (71%), and had low AFP expression (82%). METhigh expression was observed in 53% of tumors being higher in patients with viral hepatitis-associated HCC (p = 0.02) and in patients with AFP>400UI/L (p = 0.03). CA9high expression was observed in 41% of tumors and was correlated with viral hepatitis (p = 0.002), pathological vascular invasion (p = 0.007), and poor differentiation (p = 0.007). MET and CA9 expression levels significantly correlated with each other (p = 0.008). mDFS was shorter in METhigh (12.9 vs >80 months in METlow patients; p = 0.018) and CA9high (10.2 vs 34.4 months in CA9low patients; p = 0.02) populations. Combination of MET and CA9 status discriminated 3 prognostic groups. In the METhigh/CA9high group mDFS was 10.7 months, whereas mDFS was not reached in the METlow/CA9low group (p = 0.003). Using H- and MetMab scores, mDFS of the METhigh group were 12.9 months and 12.4 months respectively, and not reached in the METlow group. The METhigh/CA9low and METlow/CA9high groups were defined as intermediate risk populations (mDFS = 19 months). In multivariate analysis, tumor < 5cm (p = 0.025), uninodular morphology (p = 0.004), and CA9-low levels (p = 0.007) were independently associated with prolonged DFS. METhigh expression level was associated with shorter DFS when CA9 was excluded from the model (p = 0.024). No amplification was detected in METhigh HCC samples. Conclusion: MET expression is a useful prognostic marker in HCC. Patients with HCC overexpressing MET and CA9 represent a subgroup with poor prognosis that might benefit from MET inhibition therapy. Citation Format: Annemilai Tijeras-Raballand, Cindy Neuzillet, Miguel Albuquerque, Nathalie Colnot, Friedhelm Bladt, Manfred Klevesath, Christian Ihling, Hongxia Zheng, Maryse Baia, Christiane Copie-Bergman, Eric Raymond, Armand de Gramont, Valérie Paradis, Sandrine Faivre. High MET and CA9 expressions define a subgroup of hepatocellular carcinoma (HCC) patients with poor prognosis candidates for MET inhibition strategy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1911. doi:10.1158/1538-7445.AM2015-1911