An Interim Report Of CALGB 150607: Expression And Mutational Status Of c-MET, HGF, EGFR, KRAS, p53, c-CBL, And E-cadherin In Resected Lung Adenocarcinoma Specimens

Abstract

PURPOSE/OBJECTIVE(S): c-Met is a tyrosine kinase receptor for hepatocyte growth factor/scatter factor plays a critical role in cancer growth, invasion, and metastasis. The main objective of this study is to evaluate the correla¬tion between c-MET mutation and expression with stage and overall survival in a large group of adenocarcinoma (AC) patients. The secondary aims are to determine the correlation between overall survival and the analysis of: 1) EGFR mutation & expression, 2) TP53 mutation & expression, 3)epithelial-to-mesenchymal transition, 4) KRAS mutation, and 5) CBL mutation, and to evaluate gene amplification of c-MET in AC patients and the sera levels of circulating c-Met and HGF. MATERIALS/METHODS: We evaluated 80 adenocarcinoma patients. Standard PCR and sequencing techniques for mutational analysis of MET, EGFR exons 18-21, TP53 exons 4-10, KRAS exon 2, and CBL exons 2-16. ELISA was used to quantify soluble c-Met and HGF in pre- and post-operative sera. c-MET, phosphorylated (pMET Y1003 and Y1230/34/35), p53, HGF, EGFR, and E-cadherin expression were evaluated by IHC. Staining inten¬sity was scored on four-point scale: 0, negative; 1+, weak; 2+, moderate; 3+, strong. The extent of staining was scored similarly: 0, negative; 1+, 1-10%; 2+, 11-50%; 3+, > 50%. The product of the intensity and extent of staining yielded final scores between 0 and 9. RESULTS: In 9 patients, six non-synonymous (NS) mutations were detected in MET (SEMA domain: E168D, M362T, N375S, and Q318K; JM domain: T992I and R970C). In EGFR, the NS mutation L858R was detected in two patients. We detected 11 NS mutations in TP53 (exon 4: E68*; exon 5: V157F, R175H, I162F, H193Y, Y163D; exon 8: R273L, R273C, V274L, A276F, and G266*). Five NS mutations were detected in exon 2 of KRAS (G12C, G12V, G12D, G12S and G13V). For both c-MET and HGF, there are 65 pairs pre- and post-operative sera with no missing values. There was a significant (p=0.008) increase of soluble c-MET in post- (1750 ng/ml ± 60.2) compared to pre-operative (1584 ng/ml ± 59.2) serum samples. HGF levels were significantly increased (p=0.028) in post- (1006 pg/ml ± 70.6) com¬pared to pre-operative samples (847 pg/ml ± 56.0). The mean expressions as determined by IHC: c-MET 3.9 (±0.3); pY1230/34/35 MET 2.3 (±0.3); pY1003MET 4.8 (±0.3); HGF 4.4 (±0.3); EGFR 4.3 (±0.4); TP53 3.8 (±0.3); and E-cadherin 5.4 (±0.4) CONCLUSION: Unique MET mutations were detected in key functional domains; the SEMA domain and the JM domain. Post-operative patient sera levels were increased dramatically both in HGF and soluble MET. MET, pMET (Y1003), EGFR, E-Cadherin, HGF and P53 were highly expressed. The expression and mutation data will be correlated with clinical outcomes to identify the prognostic role of c-Met.