High-expression EGFR/cell membrane chromatography-online-high-performance liquid chromatography/mass spectrometry: rapid screening of EGFR antagonists from Semen Strychni

RATIONALE

Traditional methods for screening active compounds from complex system such as traditional Chinese medicines are relatively cumbersome and time-consuming. In order to improve this situation, we established an online analytical method for screening, separation and identification EGFR antagonists from traditional Chinese medicines, which is described in this study.

METHODS

Cells with high EGFR expression levels were used to prepare the cell membrane stationary phase for the EGFR cell membrane chromatography model with the purpose of screening active compounds. Separation of the retention fractions was achieved by the high-performance liquid chromatography, and identification was conducted via electrospray ionization quadrupole mass spectrometry. The inhibitory effects of active compounds on EGFR cell growth were also demonstrated in vitro.

RESULTS

The screening results showed that vauquline and strychnine from Semen Strychni could be active components acting on EGFR similarly to gefitinib as a control drug. Results from biological trials showed that vauquline and strychnine inhibited cell proliferation of HEK293/EGFR cells, and inhibited Erk phosphorylation, and can effectively reduce expression of downstream signaling molecules.

CONCLUSIONS

This EGFR cell membrane chromatography-online-high-performance liquid chromatography/tandem mass spectrometry method can be applied for rapid screening, separation and identification of EGFR antagonists from traditional Chinese medicines and should be useful for drug discovery with natural medicinal herbs.

Genotype-driven therapies for non-small cell lung cancer: focus on EGFR, KRAS and ALK gene abnormalities

Non-small cell lung cancers (NSCLCs) are heterogeneous cancers. In 2004, the identification of epidermal growth factor receptor (EGFR) somatic mutations provided the first glimpse of a clinically relevant NSCLC oncogene. Approximately 70% of NSCLCs with EGFR mutations (exon 19 deletions or the exon 21 L858R) attain responses to EGFR tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib, with improved response rate (RR), progression-free survival (PFS) and in some reports overall survival (OS) when compared with EGFR wildtype (WT) cases. Three randomized trials of gefitinib versus chemotherapy (IPASS, WJTOG3405, NEJ002) in stage IV NSCLC have consistently demonstrated better RR and PFS (hazard ratios of 0.48 [IPASS], 0.49 [WJTOG3405] and 0.30 [NEJ002]) for EGFR-mutated NSCLCs treated with gefitinib. Novel irreversible EGFR TKIs (afatinib, XL647, PF00299804) show similar activity in EGFR-mutated patients. A translocation involving the anaplastic lymphoma kinase (ALK) gene with EML4, identified in 2007, is the most recent oncogene found in NSCLC. Crizotinib (PF02341066), an ALK TKI, has shown impressive activity against ALK translocated NSCLC in an expanded cohort of a phase I trial (NCT00585195). Over 80 patients have been treated and the RR is ∼60% with the 6-month PFS rate exceeding 70%. A registration phase III trial of crizotinib versus second-line chemotherapy (pemetrexed/docetaxel) is underway (PROFILE 1007, NCT00932893). KRAS, EGFR mutations and ALK translocations are mutually exclusive and few EGFR WT NSCLCs respond to EGFR TKIs. The promising results of EGFR and ALK TKIs in molecular subgroups of NSCLCs herald a new age of drug and clinical trial development for patients with NSCLC.

EGFR mutant lung cancer

Thoracic oncologists traditionally have made treatment decisions based upon tumor histology, distinguishing non-small cell lung cancer (NSCLC) from small cell lung cancer (SCLC). However, recent data has revealed that at least one histological subtype of NSCLC, lung adenocarcinoma comprises multiple molecularly distinct diseases. Lung adenocarcinoma subsets now can be defined by specific 'driver' mutations in genes encoding components of the EGFR signaling pathway. Importantly, these mutations have implications regarding targeted therapy. Here, we focus on EGFR mutant NSCLC-a prime example of a clinically relevant molecular subset of lung cancer, with defined mechanisms of drug sensitivity, primary drug resistance, and acquired resistance to EGFR tyrosine kinase inhibitors. Efforts are now being made to overcome mechanisms of acquired resistance. These findings illustrate how knowledge about the genetic drivers of tumors can lead to rational targeted therapy for individual patients.

Advances in target therapy for lung cancer

Recent progress in molecular biology has shown that cancer cells acquire common phenotypes such as self-sufficiency of growth signals, resistance to anti-proliferative and apoptotic signals through the accumulation of genetic and epigenetic changes. Recently developed anticancer drugs target these molecular mechanisms and good results have been reported for various cancer types. In lung cancer, tyrosine kinase inhibitors specific for the epidermal growth factor receptor such as gefitinib and erlotinib have changed clinical practice dramatically. About half of the Japanese patients with lung cancers harbor an activating mutation of the epidermal growth factor receptor gene and they are very sensitive to epidermal growth factor receptor tyrosine kinase inhibitors. Progression-free survival of such patients is approximately 10 months when treated with gefitinib, whereas the survival for those treated with platinum doublet therapy is approximately 6 months. Target therapies against echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase fusion protein or a mutated ERBB2 (v-ERB-B avian erythroblastic leukemia viral oncogene homologue 2) present in approximately 5% and approximately 3% of the Japanese patients with adenocarcinomas, respectively, are currently under development. Addition of an anti-epidermal growth factor receptor antibody, cetuximab, or anti-vascular endothelial growth factor antibody, bevacizumab, to platinum doublet therapy significantly but modestly prolonged the survival in recent clinical trials. However, clinical development of small molecule multi-kinase inhibitors including those targeting vascular endothelial growth factor receptors, such as vandetanib, sunitinib and sorafenib, has not been very successful. Through these collaborations among clinicians, basic researchers and pharmaceutical companies, it should be possible to individualize lung cancer treatment to turn this fatal disease into a chronic disorder and, eventually, to cure it.

Shortcomings of current therapies for non-small-cell lung cancer: unmet medical needs

Non-small-cell lung cancer (NSCLC) is a major global health problem and is the leading cause of cancer death worldwide. Current treatment involves nonspecific, nonselective cytotoxic chemotherapy, which results in only a modest increase in survival and causes significant toxicity to the patient. Targeted agents are initially effective in certain small subpopulations of patients, but eventually nearly all patients become resistant to further treatment. The limitations in efficacy and safety associated with available treatments for NSCLC underscore the need for novel agents with improved efficacy and safety profiles. This review discusses the limitations of currently recommended therapies for patients with advanced NSCLC and discusses new agents in clinical development for this disease.

Epidermal growth factor receptor inhibitors and antiangiogenic agents for the treatment of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is a major global health problem and represents the leading cause of cancer-related deaths worldwide. The majority of patients with NSCLC are diagnosed with advanced-stage disease, and the prognosis for such patients is poor. The currently approved cytotoxic chemotherapy is associated with substantial limitations in both efficacy and safety. The availability of agents targeted against the epidermal growth factor receptor (EGFR), as well as the antiangiogenic agent bevacizumab, have provided some clinical benefit. Nonetheless, the efficacy of these agents is also inadequate, and resistance has emerged as a clinical problem. Numerous novel targeted therapies are now in clinical development and may have potential for overcoming the limitations associated with currently available agents. In this article we review clinical data for molecular-targeted therapies in NSCLC, with emphasis on EGFR inhibitors and antiangiogenic agents.