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G. Sica
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MINI 13 - Genetic Alterations and Testing (ID 120)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:Y. Koh, R.K. Thomas
- Coordinates: 9/08/2015, 10:45 - 12:15, 205+207
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MINI13.03 - Characterization of MET Gene and MET Protein Expression in Lung Cancer (ID 2155)
10:45 - 12:15 | Author(s): G. Sica
- Abstract
- Presentation
Background:
Activation of the MET signaling pathway can propel the growth of cancer cells in non-small cell lung cancer (NSCLC). Increased MET gene by amplification and/or polysomy can cause MET protein overexpression; less common causes include mutations, translocations, and alternative RNA splicing. Clinical trials using MET as a biomarker for selection of lung cancer patients who might most benefit from targeted therapy have experienced variable outcomes. We aimed to characterize the relationship between MET protein overexpression and MET amplification or mean copy number alterations in patients with NSCLC.
Methods:
The Lung Cancer Mutation Consortium (LCMC) is performing an ongoing study of biomarkers with patients with NSCLC from 16 cancer center sites across the United States. For this analysis, 403 cases had complete data for MET protein expression by immunohistochemistry (IHC, monoclonal antibody SP44, Ventana) and MET gene amplification by fluorescence in-situ hybridization (FISH, MET/CEP7 ratio). Pathologists evaluated MET expression using the H-score, a semi-quantitative assessment of the percentage of tumor cells with no, faint, moderate, and/or strong staining, ranging from 0-300. Spearman's correlation was used to analyze the correlation between MET protein expression (H-scores) and FISH results (MET/CEP7 ratio (N=403) and MET copy number (N=341). Protein overexpression using 5 different cut-offs was compared with amplification defined as MET/CEP7 ≥ 2.2 and high mean copy number defined as ≥ 5 MET gene copies per cell using the Fisher’s exact test. Cox Proportional Hazards models were built to examine the associations of these different definitions of positivity with prognosis, adjusting for stage of disease.
Results:
MET protein expression was significantly correlated with MET copy numbers (r=0.17, p=0.0025), but not MET/CEP7 ratio (r=-0.013, p=0.80). No significant association was observed between protein overexpression using a commonly used definition for MET positivity (“at least moderate staining in ≥ 50% tumor cells”) and MET amplification (p=0.47) or high mean copy number (p=0.09). A definition for MET protein overexpression as “≥ 30% tumor cells with strong staining” was significantly associated with both MET amplification (p=0.03) and high mean copy number (p=0.007), but a definition of “≥ 10% tumor cells with strong staining” was not significantly associated with either. Definitions of protein overexpression based on high H-scores (≥200 or ≥250) were associated with high MET mean copy numbers (p=0.03 and 0.0008, respectively), but not amplification (p=0.46 and 0.12, respectively). All 5 definitions of MET protein overexpression demonstrated a significant association with worse prognosis by survival analyses (p-values ranged from 0.001 to 0.03). High MET copy number (p=0.045) was associated with worse prognosis, but MET amplification was not (p=0.07).
Conclusion:
Evaluation of NSCLC specimens from LCMC sites confirms that MET protein expression is correlated with high MET copy number and protein overexpression is associated with worse prognosis. Definitions of MET protein overexpression as “an H-score ≥250” and “≥30% tumor cells with strong staining” were significantly associated with high mean MET copy number. It may be worth reevaluating the performance of MET as a biomarker by different definitions of positivity to predict response to MET-targeted therapies.
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MINI 25 - Trials, Radiation and Other (ID 142)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Thymoma, Mesothelioma and Other Thoracic Malignancies
- Presentations: 1
- Moderators:J.M. Clavero, R. Hassan
- Coordinates: 9/08/2015, 16:45 - 18:15, 702+704+706
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MINI25.14 - Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia (DIPNECH): Descriptive Analysis and Overall Survival (ID 3153)
16:45 - 18:15 | Author(s): G. Sica
- Abstract
- Presentation
Background:
Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare disorder characterized by proliferation of neuroendocrine cells in the bronchial wall and considered to be pre-invasive lesion for lung carcinoid tumors [1]. There is increasing rate of diagnosis of this condition due to widespread availability and use of cross sectional imaging. DIPNECH is reported as an incidental finding in approximately 5.4% of patients undergoing resection for lung neoplasms [2]. The optimal management of this condition is currently not well-established. The limited data regarding the clinicopathologic characteristics and long term outcome for patients with DIPNECH provided a strong rationale for this study.
Methods:
We employed medical records to obtain demographic, clinical characteristics and survival for patients diagnosed with DIPNECH at our institution between January 1990 to December 2014. A review of archival diagnostic material was conducted by expert pulmonary pathologists to confirm the original diagnosis. Differences in clinical characteristics and survival was assessed between patient groups defined by race, gender, age, smoking status, body habitus and treatment received. Survival was computed using the Kaplan–Meier method while univariate and multivariate models were employed to assess for significant association between patient survival and variables of interest.
Results:
A total of 27 patients were included in this analysis. The majority of patients were females (89%) and predominantly of Caucasian (66.7%) or Black (14.8%) race. The median age at diagnoses was 63 years (range: 20-77) and 61.5% of patients were non-smoker. Approximately 52% underwent surgical resection. The median overall survival (OS) was 151 months (95%CI: 39-165) while 1-year and 5-year survival rates were 95.2% and 73.2% respectively. Nineteen patients (71%) remain alive at the time of this analysis. Male patients (HR: 4.58, 95%CI: 0.76-27.67, p=0.098) and smokers (HR: 23.79; 95%CI: 0.98-579.54; p<0.052) appeared to have an inferior survival. No statistically significant difference in survival was recorded in patient subgroups defined by age, race, surgical intervention or body weight.
Conclusion:
DIPNECH is a rare condition with increasing rate of diagnosis. The overall prognosis is good in comparison to other lung neoplasms but up to a quarter of the patients do not survive beyond five years post diagnosis. Male gender and associated use of tobacco products may be associated with poor outcome. References: 1. Chassagnon, G., et al., DIPNECH: when to suggest this diagnosis on CT. Clin Radiol, 2015. 70(3): p. 317-25. 2. Ruffini, E., et al., The significance of associated pre-invasive lesions in patients resected for primary lung neoplasms. Eur J Cardiothorac Surg, 2004. 26(1): p. 165-72.
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ORAL 37 - Novel Targets (ID 146)
- Event: WCLC 2015
- Type: Oral Session
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:S.S. Ramalingam, E. Thunnissen
- Coordinates: 9/09/2015, 16:45 - 18:15, Mile High Ballroom 4a-4f
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ORAL37.07 - Lung Cancer Mutation Consortium Pathologist Panel Evaluation of MET Protein (ID 2129)
16:45 - 18:15 | Author(s): G. Sica
- Abstract
- Presentation
Background:
MET is a receptor tyrosine kinase with frequently activated signaling in lung cancers. Multiple studies indicate that MET overexpression correlates with poor clinical prognosis. Tumors with MET amplification and overexpression may respond better to MET inhibitors than tumors with low expression. The prevalence of MET overexpression in lung cancer cohorts has varied from 20%-80%, as has the proportion of patient’s testing positive for prospective clinical trials with entry based on MET overexpression. The Lung Cancer Mutation Consortium (LCMC) Pathologist Panel endeavored to standardize evaluation of MET protein expression with “Round Robin” conferences.
Methods:
508 FFPE non-small cell lung cancer specimens were stained by immunohistochemistry for MET protein expression (SP44 antibody, Ventana). Seven pathologists from LCMC sites with specialized training in MET scoring evaluated 78 Aperio-scanned images of MET-stained slides in two successive rounds of 39 different cases per round. The percentage of tumor cells with membranous and/or cytoplasmic staining at different intensities were evaluated with H-scores ranging from 0 to 300. Overall group and individual pathologist’s scores were compared with intraclass correlation coefficients (ICCs). Between rounds, a “Round Robin” teleconference was conducted to review discordant cases and improve consistency of scoring. Steps to improve scoring included: review of a Roche MET training document, sharing pictures of cases with concordant scores (Figure 1), and provision of H&E images for the second round to facilitate identification of tumor areas. Figure 1
Results:
The overall average MET H-score for the 78 cases was 165.3 (H-score range: 42.5-279.7). The average H-score was <125 for 14 specimens, 125-175 for 35 specimens, and >175 for 29 specimens. The overall group ICC comparing the consistency of H-scores from all 7 pathologists improved from 0.50 (95% confidence interval: 0.37-0.64, “fair” correlation) for the first scoring round to 0.74 (95% confidence interval: 0.64-0.83, “good” correlation) for the second round. A comparison of the individual pathologist’s ICCs demonstrated improved individual scoring consistency for all seven pathologists between rounds with an average of 0.64 (“moderate” correlation, range 0.43-0.76) for the first round and 0.82 (“almost perfect” correlation, range 0.75-0.93) for the second round.
Conclusion:
Development of standardized, reproducible strategies for evaluation of complex biomarkers, such as MET, are critical to clinical trial design. The consistency of scoring for MET protein expression and other biomarkers may be improved by continuous training and communication between pathologists with easy access to H&E images and other visual aids.
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