The evaluation of E-Cadherin and vimentin as biomarkers of clinical outcomes among patients with non-small cell lung cancer treated with erlotinib as second- or third-line therapy.

E-Cadherin and vimentin protein expression was assessed in late stage non-small cell lung cancer tumors from the placebo controlled clinical trial, NCIC-CTG BR.21, to determine if these markers had the potential to predict outcome of erlotinib therapy. E-Cadherin and vimentin protein expression levels were assessed in tumors from 95 patients, who were representative of the overall population, using semi-quantitative immunohistochemistry. The percentage of tumor cells with grades 0, 1, 2, or 3 membrane staining of E-cadherin and cytoplasmic staining of vimentin was measured. Three scoring methods and multiple cut-offs were explored to determine if these markers were able to divide patients into groups with different overall survival (OS). A cut-off point for E-cadherin of ≥40% tumor cells with staining of +2 and +3 and a cut-off for vimentin of ≥10% of tumors cell with any staining provided the optimal stratification. The OS hazard ratio (HR) for E-cadherin(+) versus E-cadherin(-) in the erlotinib-treated patients was 0.68 (0.35-1.33) compared with 1.48 (0.69-3.15) in the placebo patients and the OS (HR) for erlotinib versus placebo was 0.47 (0.26-0.88) in E-cadherin(+) patients compared with 1.12 (0.52-2.44) in the E-cadherin(-) patients. The OS (HR) for vimentin(+) versus vimentin(-) in the erlotinib-treated patients was 0.65 (0.31-1.38) compared to 2.32 (1.09-4.94) in the placebo-treated patients and the OS (HR) for erlotinib versus placebo was 0.26 (0.11-0.63) in vimentin(+) compared to 0.99 (0.55-1.76) in the vimentin(-) patients. Similar trends were observed for progression-free survival and response rate. E-Cadherin and vimentin are biomarkers worthy of additional study as predictive markers of outcome of erlotinib therapy.

Inducible expression of TGFß, snail and Zeb1 recapitulates EMT in vitro and in vivo in a NSCLC model.

The progression of cancer from non-metastatic to metastatic is the critical transition in the course of the disease. The epithelial to mesenchymal transition (EMT) is a mechanism by which tumor cells acquire characteristics that improve metastatic efficiency. Targeting EMT processes in patients is therefore a potential strategy to block the transition to metastatic cancer and improve patient outcome. To develop models of EMT applicable to in vitro and in vivo settings, we engineered NCI-H358 non-small cell lung carcinoma cells to inducibly express three well-established drivers of EMT: activated transforming growth factor ß (aTGFß), Snail or Zeb1. We characterized the morphological, molecular and phenotypic changes induced by each of the drivers and compared the different end-states of EMT between the models. Both in vitro and in vivo, induction of the transgenes Snail and Zeb1 resulted in downregulation of epithelial markers and upregulation of mesenchymal markers, and reduced the ability of the cells to proliferate. Induced autocrine expression of aTGFß caused marker and phenotypic changes consistent with EMT, a modest effect on growth rate, and a shift to a more invasive phenotype. In vivo, this manifested as tumor cell infiltration of the surrounding mouse stromal tissue. Overall, Snail and Zeb1 were sufficient to induce EMT in the cells, but aTGFß induced a more complex EMT, in which changes in extracellular matrix remodeling components were pronounced.

Loss of homotypic cell adhesion by epithelial-mesenchymal transition or mutation limits sensitivity to epidermal growth factor receptor inhibition.

Overexpression and enhanced activation of the epidermal growth factor receptor (EGFR) is frequently observed in human carcinomas. Inhibitors of EGFR signaling have shown clinical utility; however, understanding response at the molecular level is important to define patient subsets most likely to benefit, as well as to support the rational design of drug combinations. Pancreatic and colorectal tumor cell lines insensitive to EGFR inhibition were those that had lost or mutated the epithelial junction constituents E-cadherin and gamma-catenin, had lost homotypic adhesion, and often gained proteins associated with an epithelial to mesenchymal-like transition, such as vimentin, zeb1, or snail. In matched pairs of colorectal tumor cells, the epithelial lines showed an average 7-fold greater sensitivity than mesenchymal-like lines. In human pancreatic and colorectal tumor tissues, gain of mesenchymal characteristics and loss of epithelial characteristics correlated with advancing tumor stage. These data indicate an especially sensitive patient subset as well as a rationale for the combination of EGFR antagonists with agents that affect the epithelial to mesenchymal-like transition process as a mechanism to enhance sensitivity for more advanced mesenchymal-like tumors.

OSI-930: a novel selective inhibitor of Kit and kinase insert domain receptor tyrosine kinases with antitumor activity in mouse xenograft models.

OSI-930 is a novel inhibitor of the receptor tyrosine kinases Kit and kinase insert domain receptor (KDR), which is currently being evaluated in clinical studies. OSI-930 selectively inhibits Kit and KDR with similar potency in intact cells and also inhibits these targets in vivo following oral dosing. We have investigated the relationships between the potency observed in cell-based assays in vitro, the plasma exposure levels achieved following oral dosing, the time course of target inhibition in vivo, and antitumor activity of OSI-930 in tumor xenograft models. In the mutant Kit-expressing HMC-1 xenograft model, prolonged inhibition of Kit was achieved at oral doses between 10 and 50 mg/kg and this dose range was associated with antitumor activity. Similarly, prolonged inhibition of wild-type Kit in the NCI-H526 xenograft model was observed at oral doses of 100 to 200 mg/kg, which was the dose level associated with significant antitumor activity in this model as well as in the majority of other xenograft models tested. The data suggest that antitumor activity of OSI-930 in mouse xenograft models is observed at dose levels that maintain a significant level of inhibition of the molecular targets of OSI-930 for a prolonged period. Furthermore, pharmacokinetic evaluation of the plasma exposure levels of OSI-930 at these effective dose levels provides an estimate of the target plasma concentrations that may be required to achieve prolonged inhibition of Kit and KDR in humans and which would therefore be expected to yield a therapeutic benefit in future clinical evaluations of OSI-930.