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MO12 - Prognostic and Predictive Biomarkers III (ID 96)
- Event: WCLC 2013
- Type: Mini Oral Abstract Session
- Track: Medical Oncology
- Presentations: 1
MO12.04 - Biomarker Analysis of NCIC Clinical Trials Group IND.196, a Phase I study of erlotinib plus foretinib in advanced pretreated non-small cell lung cancer patients (ID 3148)
10:30 - 12:00 | Author(s): T. Zhang
Upregulation of MET and more recently AXL have been described as potential mechanisms of resistance to EGFR tyrosine kinase inhibitors in NSCLC. We explored the impact of baseline MET and AXL tumour expression and circulating hepatocyte growth factor levels, (HGF), in advanced NSCLC patients receiving erlotinib plus foretinib, an oral multi-targeted kinase inhibitor of MET, RON, AXL, TIE-2 and VEGFR.
Advanced NSCLC patients that previously received one or two lines of chemotherapy were treated in IND.196, a phase I dose-finding trial with an initial two-week run-in of single agent erlotinib (100-150 mg daily). If erlotinib was well tolerated, foretinib was then added (30-45 mg daily). Submission of tumour samples (archival or fresh) was mandatory, and circulating HGF levels were determined at baseline and on treatment. Tumour samples were genotyped using Sequenom MassARRAY analysis. MET and AXL expression were determined by immunohistochemistry. For AXL, the human Axl affinity purified polyclonal goat IgG antibody (R&D systems, AF154, Minneapolis MN) was scored manually. For MET, the anti-total MET (SP-44) rabbit monoclonal antibody (Ventana Medical Systems, Tucson AZ) was scored using the Benchmark XT autostainer. Staining intensity (0-3+) and percent cells stained were used to calculate the H-score; H-scores >100 were deemed positive for AXL, and >200 positive for MET.
Of 31 patients enrolled, 28 were evaluable for response to combination therapy, with a recommended phase II dose of erlotinib 150 mg daily for a 2-week run-in and then foretinib 30 mg daily added. The overall response rate in the intent to treat population (RECIST 1.1) was 16.1% (95% CI 5.5-33.7%), with partial responses (PR) seen in 5/31 patients and a median response duration of 17.9 months (range 3.6-17.9). Stable disease was seen in 42% (13/31), with a median duration of 4.8 months (95% CI 2.4-15.4). Tumour samples were submitted for 25 patients; 15 had sufficient tissue for genotyping, 17 for assessment of MET, and 16 for AXL expression. 2/5 responding patients had confirmed EGFR mutations, (1 wildtype, 2 unknown). Another 5 had KRAS mutations, one with >20% reduction in tumour size but SD by RECIST. Of 17 patients with MET IHC results, 71% (12/17) were positive. PR was seen in 3/12 patients with MET-positive tumours, (2 with EGFR mutations, 1 wildtype). No response was seen in those with MET-negative tumours. Of 16 samples with AXL IHC results, 9 were positive (56%). PR was seen in 2/9 with AXL-positive tumours and 2/6 with AXL-negative tumours. AXL expression was not seen in samples with EGFR mutations, but 3/5 KRAS mutant samples were AXL positive. Assessment of circulating HGF levels will be presented at the 2013 WCLC meeting.
Baseline MET expression, uncontrolled for EGFR status, may be associated with response to combination erlotinib/foretinib. No correlation between baseline AXL expression and response was seen although the sample size is small. Further study is needed to control for the impact of EGFR mutation status on response, and to assess whether combination erlotinib/foretinib can overcome resistance to EGFR TKI therapy mediated by MET and AXL.
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