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Biomarker Analyses from a Placebo-Controlled Phase II Study Evaluating Erlotinib ± Onartuzumab in Advanced Non–Small Cell Lung Cancer: MET Expression Levels Are Predictive of Patient Benefit

Koeppen, H., Yu, W., Zha, J., Pandita, A., Penuel, E., Rangell, L., Raja, R., Mohan, S., Patel, R., Desai, R., Fu, L., Do, A., Parab, V., Xia, X., Januario, T., Louie, S.G., Filvaroff, E., Shames, D.S., Wistuba, I., Lipkind, M., Huang, J., Lazarov, M., Ramakrishnan, V., Amler, L., Phan, S.C., Patel, P., Peterson, A., Yauch, R.L.

Purpose
In a recent phase II study of onartuzumab (MetMAb), patients whose non–small cell lung cancer (NSCLC) tissue scored as positive for MET protein by immunohistochemistry (IHC) experienced a significant benefit with onartuzumab plus erlotinib (O+E) versus erlotinib. We describe development and validation of a standardized MET IHC assay and, retrospectively, evaluate multiple biomarkers as predictors of patient benefit.

Experimental Design
Biomarkers related to MET and/or EGF receptor (EGFR) signaling were measured by IHC, FISH, quantitative reverse transcription PCR, mutation detection techniques, and ELISA.

Results
A positive correlation between IHC, Western blotting, and MET mRNA expression was observed in NSCLC cell lines/tissues. An IHC scoring system of MET expression taking proportional and intensity-based thresholds into consideration was applied in an analysis of the phase II study and resulted in the best differentiation of outcomes. Further analyses revealed a nonsignificant overall survival (OS) improvement with O+E in patients with high MET copy number (mean ≥5 copies/cell by FISH); however, benefit was maintained in “MET IHC-positive”/MET FISH-negative patients (HR, 0.37; P = 0.01). MET, EGFR, amphiregulin, epiregulin, or HGF mRNA expression did not predict a significant benefit with onartuzumab; a nonsignificant OS improvement was observed in patients with high tumor MET mRNA levels (HR, 0.59; P = 0.23). Patients with low baseline plasma hepatocyte growth factor (HGF) exhibited an HR for OS of 0.519 (P = 0.09) in favor of onartuzumab treatment.

Conclusions
MET IHC remains the most robust predictor of OS and progression-free survival benefit from O+E relative to all examined exploratory markers.

Citation

Koeppen, H., Yu, W., Zha, J., Pandita, A., Penuel, E., Rangell, L., Raja, R., Mohan, S., Patel, R., Desai, R., Fu, L., Do, A., Parab, V., Xia, X., Januario, T., Louie, S.G., Filvaroff, E., Shames, D.S., Wistuba, I., Lipkind, M., Huang, J., Lazarov, M., Ramakrishnan, V., Amler, L., Phan, S.C., Patel, P., Peterson, A., Yauch, R.L. "Biomarker Analyses from a Placebo-Controlled Phase II Study Evaluating Erlotinib ± Onartuzumab in Advanced Non–Small Cell Lung Cancer: MET Expression Levels Are Predictive of Patient Benefit" Clinical Cancer Research (2014): 4,488–98