Molecular mechanisms and modulation of key pathways underlying the synergistic interaction of sorafenib with erlotinib in non-small-cell-lung cancer (NSCLC) cells.

Combination of drugs with different targets is a logical approach to overcome multilevel cross-stimulation among key pathways in NSCLC progression such as EGFR, K-Ras and VEGFR. The sorafenib-erlotinib combination showed clinical activity and acceptable safety. Therefore, we evaluated mechanisms underlying sorafenib-erlotinib interaction in seven NSCLC cell lines selected for their heterogeneous pattern of EGFR and Raf-kinase-inhibitor protein (RKIP) expression, and EGFR/K-Ras mutations. Pharmacologic interaction was studied using MTT/SRB assays and the combination index (CI) method, while effects on EGFR, Erk1/2 and Akt phosphorylation, cell cycle and apoptosis were studied with western-blot, ELISA, and flow cytometry. Intracellular drug concentrations were measured with LC-MS/MS, whereas kinase activity profiles were generated on tyrosine kinase peptide substrate arrays. Synergism was detected in all cell lines, with CIs < 0.6 in K-Ras mutated A549, SW1573 and H460, as well as in H1975 (EGFR-T790M) cells. Sorafenib slowed cell cycle progression and induced apoptosis, which was significantly increased in the combination. Moreover, sorafenib reduced Akt/ERK phosphorylation in erlotinib-resistant cells, associated with significant RKIP up-regulation. No direct drug interaction was detected by LC-MS/MS measurement, while lysates from A549 and H1975 cells exposed to erlotinib+sorafenib showed a significant inhibition in the phosphorylation of 16 overlapping peptides, including sites from RAF, VEGFR2, PDGFR, CDK2 and SRC, suggesting new markers to identify NSCLC patients who are likely to respond to this treatment. In conclusion, several mechanisms, including apoptosis-induction, modulation of expression/phosphorylation of RKIP and crucial kinases contribute to erlotinib-sorafenib synergistic interaction and should be evaluated in future trials for the rational development of this combination in NSCLC.

VeriStrat(®) has prognostic value in advanced stage NSCLC patients treated with erlotinib and sorafenib.

BACKGROUND: The serum proteomic test VeriStrat has been shown to be able to classify advanced non-small cell lung cancer (NSCLC) patients for overall survival (OS) after treatment with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). In this study, VeriStrat was evaluated as a pre-treatment stratification tool in patients with advanced stage NSCLC for treatment with the combination of erlotinib and sorafenib, considering both OS and progression-free survival (PFS) as end points. METHODS: Serum samples from 50 patients treated within the context of a phase II trial of first-line erlotinib and sorafenib were analysed with VeriStrat, a fully locked mass spectrometry-based test that identifies patients likely to have good or poor outcome on EGFR therapy based on eight distinct features in mass spectra. Analysis was performed fully blinded to all clinical data, and then the outcome data were analysed with respect to the obtained serum classifications. RESULTS: VeriStrat classified pre-treatment samples into two groups, VeriStrat Good and VeriStrat Poor, which were significantly different in OS (hazard ratio (HR) 0.30, log-rank P=0.009) and in PFS (HR 0.40, log-rank P=0.035). CONCLUSION: VeriStrat has shown its potential for stratification of unselected, advanced stage NSCLC patients treated in first line with a combination of erlotinib and sorafenib.

Simple and selective method for the determination of various tyrosine kinase inhibitors used in the clinical setting by liquid chromatography tandem mass spectrometry.

A fast, sensitive, universal and accurate method for the determination of four different tyrosine kinase inhibitors from biological material was developed using LC-MS/MS techniques. Utilizing a simple protein precipitation with acetonitrile a 20 microl sample volume of biological matrixes can be extracted at 4 degrees C with minimal effort. After centrifugation the sample extract is introduced directly onto the LC-MS/MS system without further clean-up and assayed across a linear range of 1-4000 ng/ml. Chromatography was performed using a Dionex Ultimate 3000 with a Phenomenex prodigy ODS3 (2.0 mm x 100 mm, 3 microm) column and eluted at 200 microl/min with a tertiary mobile phase consisting of 20mM ammonium acetate:acetonitrile:methanol (2.5:6.7:8.3%). Injection volume varied from 0.1 microl to 1 microl depending on the concentration of the drug observed. Samples were observed to be stable for a maximum of 48 h after extraction when kept at 4 degrees C. Detection was performed using a turbo-spray ionization source and mass spectrometric positive multi-reaction-monitoring-mode (+MRM) for Gefitinib (447.1 m/z; 127.9 m/z), Erlotinib (393.9 m/z; 278.2 m/z), Sunitinib (399.1 m/z; 283.1 m/z) and Sorafenib (465.0 m/z; 251.9 m/z) at an ion voltage of +3500 V. The accuracy, precision and limit-of-quantification (LOQ) from cell culture medium were as follows: Gefitinib: 100.2+/-3.8%, 11.2 nM; Erlotinib: 101.6+/-3.7%, 12.7 nM; Sunitinib: 100.8+/-4.3%, 12.6 nM; Sorafenib: 93.9+/-3.0%, 10.8 nM, respectively. This was reproducible for plasma, whole blood, and serum. The method was observed to be linear between the LOQ and 4000 ng/ml for each analyte. Effectiveness of the method is illustrated with the analysis of samples from a cellular accumulation investigation and from determination of steady state concentrations in clinically treated patients.

CD133+ circulating haematopoietic progenitor cells predict for response to sorafenib plus erlotinib in non-small cell lung cancer patients.

BACKGROUND: Blood-based biomarkers may be particularly useful for patient selection and prediction of treatment response for angiogenesis inhibitors. Circulating endothelial cells (CECs) and haematopoietic progenitor cells (HPCs) might have a role in tumour angiogenesis and in tumour growth. Measurement of CECs and HPCs in the blood of patients could be a simple, non-invasive way to monitor or predict responses to treatment. METHODS: (VEGFR2(+)) CECs(,) (CD133(+)) HPCs, plasma vascular endothelial growth factor (VEGF) and erythropoietin were measured in blood from 25 non-small cell lung cancer (NSCLC) patients before and during treatment with sorafenib plus erlotinib (SO/ER). In order to assess the drug specificity of changes in CECs and HPCs, 18 patients treated with bevacizumab plus erlotinib (BV/ER) and 10 patients with erlotinib (ER) monotherapy were studied. Response was measured in all patient groups by Response Evaluation Criteria in Solid Tumors (RECIST). RESULTS: At day 7, SO/ER-treated patients showed a three-fold increase in CECs (P<0.0001) comparable to BV/ER-treated patients (P<0.01), and the CECs did not change with erlotinib treatment (P=0.8). At day 7, CD133(+)/HPCs decreased with SO/ER treatment (P<0.0001). HPC numbers did not change with either BV/ER or erlotinib. In SO/ER-treated patients pre-treatment CD133(+)/HPCs were significantly lower in responders (P=0.01) and pre-treatment CD133(+)/HPC numbers lower than the median correlated with a longer time-to-progression (TTP) (P=0.037). CONCLUSION: Pre-treatment CD133(+)/HPCs are a promising candidate biomarker to further explore for use in selecting NSCLC patients who might benefit from SO/ER treatment.

[New therapies for the treatment of advanced non-small cell lung cancer: inhibitors of the epidermal growth factor receptor and angiogenesis]. / Nieuwe middelen voor de behandeling van gemetastaseerd niet-kleincellig longcarcinoom: remmers van de epidermale groeifactorreceptor en van de angiogenese.

The recently developed 'targeted' therapies, epidermal growth factor receptor (EGFR) inhibitors and angiogenesis inhibitors, target specific tumour characteristics. EGFR inhibitors, such as gefitinib and erlotinib, can lead to remission, particularly in non-small cell lung cancer (NSCLC) with specific EGFR mutations. These mutations occur more frequently in Asians, women, non-smokers and those with adenocarcinomas. Other mutations in EGFR and K-ras genes lead to resistance. EGFR inhibitors offered no benefit to untreated patients with advanced NSCLC. In previously treated patients, however, erlotinib increased survival by 2 months. Optimal patient selection criteria for EGFR inhibitor therapy is still under investigation. The angiogenesis inhibitor bevacizumab is an antibody that targets vascular endothelial growth factor receptor. The addition of bevacizumab to chemotherapy increased median survival by 2 months when given as first-line therapy for advanced NSCLC. The combination of EGFR and angiogenesis inhibitors is a rational anticancer treatment and is being studied. These new therapies are expected to help improve and individualize the treatment of advanced NSCLC.