MET increased gene copy number and primary resistance to gefitinib therapy in non-small-cell lung cancer patients.

BACKGROUND: MET amplification has been detected in approximately 20% of non-small-cell lung cancer patients (NSCLC) with epidermal growth factor receptor (EGFR) mutations progressing after an initial response to tyrosine kinase inhibitor (TKI) therapy. PATIENTS AND METHODS: We analyzed MET gene copy number using FISH in two related NSCLC cell lines, one sensitive (HCC827) and one resistant (HCC827 GR6) to gefitinib therapy and in two different NSCLC patient populations: 24 never smokers or EGFR FISH-positive patients treated with gefitinib (ONCOBELL cohort) and 182 surgically resected NSCLC not exposed to anti-EGFR agents. RESULTS: HCC827 GR6-resistant cell line displayed MET amplification, with a mean MET copy number >12, while sensitive HCC827 cell line had a mean MET copy number of 4. In the ONCOBELL cohort, no patient had gene amplification and MET gene copy number was not associated with outcome to gefitinib therapy. Among the surgically resected patients, MET was amplified in 12 cases (7.3%) and only four (2.4%) had a higher MET copy number than the resistant HCC827 GR6 cell line. CONCLUSIONS: MET gene amplification is a rare event in patients with advanced NSCLC. The development of anti-MET therapeutic strategies should be focused on patients with acquired EGFR-TKI resistance.

Evidence for cell fusion is absent in vascular lesions associated with pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a fatal disease associated with severe remodeling of the large and small pulmonary arteries. Increased accumulation of inflammatory cells and apoptosis-resistant cells are contributing factors. Proliferative apoptosis-resistant cells expressing CD133 are increased in the circulation of PAH patients. Circulating cells can contribute to tissue repair via cell fusion and heterokaryon formation. We therefore hypothesized that in the presence of increased leukocytes and CD133-positive (CD133(pos)) cells in PAH lung tissue, cell fusion and resulting genomic instability could account for abnormal cell proliferation and the genesis of vascular lesions. We performed analyses of CD45/CD133 localization, cell fusion, and proliferation during late-stage PAH in human lung tissue from control subjects and subjects with idiopathic (IPAH) and familial (FPAH) PAH. Localization, proliferation, and quantitation of cell populations in individual patients were performed by immunolocalization. The occurrence of cellular fusion in vascular lesions was analyzed in lung tissue by fluorescence in situ hybridization. We found the accumulation of CD45(pos) leukocytic cells in the tissue parenchyma and perivascular regions in PAH patients and less frequently observed myeloid cells (CD45/CD11b). CD133(pos) cells were detected in occlusive lesions and perivascular areas in those with PAH and were more numerous in those with IPAH lesions than in FPAH lesions. Cells coexpressing CD133 and smooth muscle alpha-actin were occasionally observed in occlusive lesions and perivascular areas. Proliferating cells were more prominent in IPAH lesions and colocalized with CD45 or CD133. We found no evidence of increased ploidy to suggest cell fusion. Taken together, these data suggest that abnormal lesion formation in PAH occurs in the absence of cell fusion.

Primary resistance to cetuximab therapy in EGFR FISH-positive colorectal cancer patients.

The impact of KRAS mutations on cetuximab sensitivity in epidermal growth factor receptor fluorescence in situ hybridisation-positive (EGFR FISH+) metastatic colorectal cancer patients (mCRC) has not been previously investigated. In the present study, we analysed KRAS, BRAF, PI3KCA, MET, and IGF1R in 85 mCRC treated with cetuximab-based therapy in whom EGFR status was known. KRAS mutations (52.5%) negatively affected response only in EGFR FISH+ patients. EGFR FISH+/KRAS mutated had a significantly lower response rate (P=0.04) than EGFR FISH+/KRAS wild type patients. Four EGFR FISH+ patients with KRAS mutations responded to cetuximab therapy. BRAF was mutated in 5.0% of patients and none responded to the therapy. PI3KCA mutations (17.7%) were not associated to cetuximab sensitivity. Patients overexpressing IGF1R (74.3%) had significantly longer survival than patients with low IGF1R expression (P=0.006), with no difference in response rate. IGF1R gene amplification was not detected, and only two (2.6%) patients, both responders, had MET gene amplification. In conclusion, KRAS mutations are associated with cetuximab failure in EGFR FISH+ mCRC, even if it does not preclude response. The rarity of MET and IGF1R gene amplification suggests a marginal role in primary resistance. The potential prognostic implication of IGF1R expression merits further evaluation.

Multimodal retinal image registration for optic disk segmentation.

OBJECTIVES: The analysis of the optic disk morphology with the means of the scanning laser tomography is an important step for glaucoma diagnosis. A method we developed for optic disk segmentation in images of the scanning laser tomograph is limited by noise, non-uniform illumination and presence of blood vessels. Inspired by recent medical research, we wanted to develop a tool for improving optic disk segmentation by registration of images of the scanning laser tomograph and color fundus photographs and by applying a method we developed for optic disk segmentation in color fundus photographs. METHODS: The segmentation of the optic disk for glaucoma diagnosis in images of the scanning laser tomograph is based on morphological operations, detection of anatomical structures and active contours and has been described in a previous paper. The segmentation of the optic disk in the fundus photographs is based on nonlinear filtering, Canny edge detector and a modified Hough transform. The registration is based on mutual information using simulated annealing for finding maxima. RESULTS: The registration was successful 86.8% of the time when tested on 174 images. Results of the registration have shown a very low displacement error of a maximum of about 5 pixels. The correctness of the registration was manually evaluated by measuring distances between the real vessel borders and those from the registered image. CONCLUSIONS: We have developed a method for the registration of images of the scanning laser tomograph and fundus photographs. Our first experiments showed that the optic disk segmentation could be improved by fused information from both image modalities.