Inhibition of the T790M gatekeeper mutant of the epidermal growth factor receptor by EXEL-7647

Optimization of the 4-anilinoquin(az)oline scaffold as epidermal growth factor receptor (EGFR) inhibitors for chordoma utilizing a toxicology profiling assay platform

The 4-anilinoquin(az)oline is a well-known kinase inhibitor scaffold incorporated in clinical inhibitors including gefitinib, erlotinib, afatinib, and lapatinib, all of which have previously demonstrated activity against chordoma cell lines in vitro. We screened a focused array of compounds based on the 4-anilinoquin(az)oline scaffold against both U-CH1 and the epidermal growth factor receptor (EGFR) inhibitor resistant U-CH2. To prioritize the hit compounds for further development, we screened the compound set in a multiparameter cell health toxicity assay. The de-risked compounds were then screened against a wider panel of patient derived cell lines and demonstrated low micromolar efficacy in cells. We also investigated the properties that gave rise to the toxophore markers, including the structural and electronic features, while optimizing for EGFR in-cell target engagement. These de-risked leads present a potential new therapeutic avenue for treatment of chordomas and new chemical tools and probe compound 45 (UNC-CA359) to interrogate EGFR mediated disease phenotypes.

Yang-Yin-Jie-Du decoction overcomes gefitinib resistance in non-small cell lung cancer via down-regulation of the PI3K/Akt signalling pathway

CONTEXT

Yang-Yin-Jie-Du Decoction (YYJDD) was used to improve gefitinib efficacy in our clinical practice, but its mechanism remains unclear.

OBJECTIVE

This study explored if YYJDD could reverse gefitinib resistance.

MATERIALS AND METHODS

H1975 cells were exposed to control, 10 μM gefitinib, 3.2 mg/mL YYJDD or combination treatment. Cell viability was detected by MTT during 0-96 h. Apoptosis and the PI3K/Akt proteins were tested by flow cytometry and western-blot at 24 h. LY294002 was applied to further determine the role of the PI3K/Akt. 23 BALB/c nude xenograft mice received normal saline (n = 5), 80 mg/kg gefitinib (n = 6), 2.35 g/kg lyophilised powder of YYJDD (n = 6) or combination treatment (n = 6) by gavage for 4 weeks and submitted to TUNEL, immunohistochemistry, and western-blot.

RESULTS

In vitro, gefitinib (IC₅₀: 20.68 ± 2.06 μM) and YYJDD (IC₅₀: 6.6 ± 0.21 mg/mL) acted in a moderate synergistic way. Combination treatment inhibited cell viability from 100% to 25.66%. Compared to gefitinb (33.23 ± 3.99%), cell apoptosis was increased with combination treatment (54.11 ± 7.32%), accompanied by down-regulation of the PI3K/Akt. LY294002 further inhibited cell viability, increased apoptosis, and down-regulated p-Akt/Akt. In vivo, the tumour sizes in the combination group (1165.13 ± 157.79 mm³) were smaller than gefitinib alone (1630.66 ± 208.30 mm³). The positive rate of TUNEL staining was increased by combination treatment (22.33 ± 2.75%) versus gefitinib (7.37 ± 0.87%), while the PI3K/Akt was down-regulated.

DISCUSSION AND CONCLUSION

YYJDD has potential to overcome gefitinib resistance. Future investigations should be focussed on its specific targets.

In Vivo Efficacy of Tesevatinib in EGFR-Amplified Patient-Derived Xenograft Glioblastoma Models May Be Limited by Tissue Binding and Compensatory Signaling

Tesevatinib is a potent oral brain penetrant EGFR inhibitor currently being evaluated for glioblastoma therapy. Tesevatinib distribution was assessed in wild-type (WT) and Mdr1a/b^(-/-)Bcrp^(-/-) triple knockout (TKO) FVB mice after dosing orally or via osmotic minipump; drug-tissue binding was assessed by rapid equilibrium dialysis. Two hours after tesevatinib dosing, brain concentrations in WT and TKO mice were 0.72 and 10.03 μg/g, respectively. Brain-to-plasma ratios (Kp) were 0.53 and 5.73, respectively. With intraperitoneal infusion, brain concentrations were 1.46 and 30.6 μg/g (Kp 1.16 and 25.10), respectively. The brain-to-plasma unbound drug concentration ratios were substantially lower (WT mice, 0.03-0.08; TKO mice, 0.40-1.75). Unbound drug concentrations in brains of WT mice were 0.78 to 1.59 ng/g. In vitro cytotoxicity and EGFR pathway signaling were evaluated using EGFR-amplified patient-derived glioblastoma xenograft models (GBM12, GBM6). In vivo pharmacodynamics and efficacy were assessed using athymic nude mice bearing either intracranial or flank tumors treated by oral gavage. Tesevatinib potently reduced cell viability [IC₅₀ GBM12 = 11 nmol/L (5.5 ng/mL), GBM6 = 102 nmol/L] and suppressed EGFR signaling in vitro However, tesevatinib efficacy compared with vehicle in intracranial (GBM12, median survival: 23 vs. 18 days, P = 0.003) and flank models (GBM12, median time to outcome: 41 vs. 33 days, P = 0.007; GBM6, 44 vs. 33 days, P = 0.007) was modest and associated with partial inhibition of EGFR signaling. Overall, tesevatinib efficacy in EGFR-amplified PDX GBM models is robust in vitro but relatively modest in vivo, despite a high brain-to-plasma ratio. This discrepancy may be explained by drug-tissue binding and compensatory signaling.

Secondary Resistant Mutations to Small Molecule Inhibitors in Cancer Cells

Secondary resistant mutations in cancer cells arise in response to certain small molecule inhibitors. These mutations inevitably cause recurrence and often progression to a more aggressive form. Resistant mutations may manifest in various forms. For example, some mutations decrease or abrogate the affinity of the drug for the protein. Others restore the function of the enzyme even in the presence of the inhibitor. In some cases, resistance is acquired through activation of a parallel pathway which bypasses the function of the drug targeted pathway. The Catalogue of Somatic Mutations in Cancer (COSMIC) produced a compendium of resistant mutations to small molecule inhibitors reported in the literature. Here, we build on these data and provide a comprehensive review of resistant mutations in cancers. We also discuss mechanistic parallels of resistance.

Combined inhibition of MEK and PI3K pathways overcomes acquired resistance to EGFR-TKIs in non-small cell lung cancer

Compensatory activation of the signal transduction pathways is one of the major obstacles for the targeted therapy of non-small cell lung cancer (NSCLC). Herein, we present the therapeutic strategy of combined targeted therapy against the MEK and phosphoinositide-3 kinase (PI3K) pathways for acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in NSCLC. We investigated the efficacy of combined trametinib plus taselisib therapy using experimentally established EGFR-TKI-resistant NSCLC cell lines. The results showed that the feedback loop between MEK/ERK and PI3K/AKT pathways had developed in several resistant cell lines, which caused the resistance to single-agent treatment with either inhibitor alone. Meanwhile, the combined therapy successfully regulated the compensatory activation of the key intracellular signals and synergistically inhibited the cell growth of those cells in vitro and in vivo. The resistance mechanisms for which the dual kinase inhibitor therapy proved effective included (MET) mesenchymal-epithelial transition factor amplification, induction of epithelial-to-mesenchymal transition (EMT) and EGFR T790M mutation. In further analysis, the combination therapy induced the phosphorylation of p38 MAPK signaling, leading to the activation of apoptosis cascade. Additionally, long-term treatment with the combination therapy induced the conversion from EMT to mesenchymal-to-epithelial transition in the resistant cell line harboring EMT features, restoring the sensitivity to EGFR-TKI. In conclusion, our results indicate that the combined therapy using MEK and PI3K inhibitors is a potent therapeutic strategy for NSCLC with the acquired resistance to EGFR-TKIs.

EphB4: A promising target for upper aerodigestive malignancies

The erythropoietin-producing hepatocellular carcinoma (Eph) receptors are the largest family of receptor tyrosine kinases (RTKs) that include two major subclasses, EphA and EphB. They form an important cell communication system with critical and diverse roles in a variety of biological processes during embryonic development. However, dysregulation of the Eph/ephrin interactions is implicated in cancer contributing to tumour growth, metastasis, and angiogenesis. Here, we focus on EphB4 and review recent developments in elucidating its role in upper aerodigestive malignancies to include lung cancer, head and neck cancer, and mesothelioma. In particular, we summarize information regarding EphB4 structure/function and role in disease pathobiology. We also review the data supporting EphB4 as a potential pharmacological and immunotherapy target and finally, progress in the development of new therapeutic strategies including small molecule inhibitors of its activity is discussed. The emerging picture suggests that EphB4 is a valuable and attractive therapeutic target for upper aerodigestive malignancies.

Targeting receptor tyrosine kinase EphB4 in cancer therapy

Eph receptors and their Eph receptor-interacting (ephrin) ligands together form an important cell communication system with diverse roles. Experimental evidence demonstrated Eph receptor bidirectional signaling with both tumor-suppressing and tumor-promoting activities in cancer cells. The tyrosine kinase EphB4, a member of the Eph receptor family, has been associated with tumor angiogenesis, growth and metastasis, thus making it a valuable and attractive target for drug design for therapeutic applications. In the past decade, many studies have focused on elucidating the structure and function of EphB4 in complex with its ligand ephrinB2 for their role in carcinogenesis. Meanwhile, an array of compounds targeting EphB4 have been studied and several selective inhibitors have been tested in clinical studies. This review discusses the structure and function of the EphB4 receptor, analyzes its potential as a target for anticancer therapy, and summarizes the information about inhibitors of EphB4 kinase activity. Conclusively, EphB4 is a challenging but promising therapeutic target in cancer.

Tesevatinib ameliorates progression of polycystic kidney disease in rodent models of autosomal recessive polycystic kidney disease

AIM

To investigate the therapeutic potential of tesevatinib (TSV), a unique multi-kinase inhibitor currently in Phase II clinical trials for autosomal dominant polycystic kidney disease (ADPKD), in well-defined rodent models of autosomal recessive polycystic kidney disease (ARPKD).

METHODS

We administered TSV in daily doses of 7.5 and 15 mg/kg per day by I.P. to the well characterized bpk model of polycystic kidney disease starting at postnatal day (PN) 4 through PN21 to assess efficacy and toxicity in neonatal mice during postnatal development and still undergoing renal maturation. We administered TSV by oral gavage in the same doses to the orthologous PCK model (from PN30 to PN90) to assess efficacy and toxicity in animals where developmental processes are complete. The following parameters were assessed: Body weight, total kidney weight; kidney weight to body weight ratios; and morphometric determination of a cystic index and a measure of hepatic disease. Renal function was assessed by: Serum BUN; creatinine; and a 12 h urinary concentrating ability. Validation of reported targets including the level of angiogenesis and inhibition of angiogenesis (active VEGFR2/KDR) was assessed by Western analysis.

RESULTS

This study demonstrates that: (1) in vivo pharmacological inhibition of multiple kinase cascades with TSV reduced phosphorylation of key mediators of cystogenesis: EGFR, ErbB2, c-Src and KDR; and (2) this reduction of kinase activity resulted in significant reduction of renal and biliary disease in both bpk and PCK models of ARPKD. The amelioration of disease by TSV was not associated with any apparent toxicity.

CONCLUSION

The data supports the hypothesis that this multi-kinase inhibitor TSV may provide an effective clinical therapy for human ARPKD.

Targeting Neovasculature with Multitargeted Antiangiogenesis Tyrosine Kinase Inhibitors in Non-small Cell Lung Cancer

Chemotherapy has reached a plateau in the efforts for survival improvement in non-small cell lung cancer (NSCLC). The growing knowledge of NSCLC molecular pathobiology has led to the development of new treatments that target specific tumor functions. Angiogenesis is a tumor function leading to the formation of new tumor vessels that are crucial for its survival. Although vascular endothelial growth factor (VEGF) plays a primary role in angiogenesis, the inhibition of the VEGF pathway with VEGF-receptor (VEGFR) tyrosine kinase inhibitors (TKIs) is associated with a modest survival benefit due to the development of resistance by the tumor that has been mainly attributed to the up-regulation of other stimulators of angiogenesis. Thus, the use of multitargeted antiangiogenesis TKIs (MATKIs) for simultaneous inhibition of multiple angiogenic pathways has been proposed. This review summarizes data about novel treatment strategies incorporating the inhibition of angiogenesis with MATKIs in NSCLC. The data from all relevant studies shows that MATKIs do not offer additional survival benefit to currently available chemotherapeutic options in unselected NSCLC patients. However, the diversity in disease response to MATKI-containing regimens implies that specific patient subgroups may benefit from or be harmed by these agents. In this context, most studies agree that the VEGFR-targeting MATKIs are harmful in squamous NSCLC while specific MATKIs (i.e., motesanib, vandetanib and nintedanib) are associated with improved progression free survival in non-squamous NSCLC. However, overall survival benefit was found only in adenocarcinoma and Asian non-squamous NSCLC patients with the use of nintedanib and motesanib, respectively.

Emerging Therapies for Childhood Polycystic Kidney Disease

Cystic kidney diseases comprise a varied collection of hereditary disorders, where renal cysts comprise a major element of their pleiotropic phenotype. In pediatric patients, the term polycystic kidney disease (PKD) commonly refers to two specific hereditary diseases, autosomal recessive polycystic kidney disease (ARPKD) and autosomal dominant polycystic kidney disease (ADPKD). Remarkable progress has been made in understanding the complex molecular and cellular mechanisms of renal cyst formation in ARPKD and ADPKD. One of the most important discoveries is that both the genes and proteins products of ARPKD and ADPKD interact in a complex network of genetic and functional interactions. These interactions and the shared phenotypic abnormalities of ARPKD and ADPKD, the "cystic phenotypes" suggest that many of the therapies developed and tested for ADPKD may be effective in ARPKD as well. Successful therapeutic interventions for childhood PKD will, therefore, be guided by knowledge of these molecular interactions, as well as a number of clinical parameters, such as the stage of the disease and the rate of disease progression.

Construction of a novel cell-based assay for the evaluation of anti-EGFR drug efficacy against EGFR mutation

Epidermal growth factor receptor (EGFR) overexpression and EGFR-mediated signaling pathway dysregulation have been observed in tumors from patients with various cancers, especially non-small cell lung cancer. Thus, several anti-EGFR drugs have been developed for cancer therapy. For patients with known EGFR activating mutations (EGFR exon 19 in-frame deletions and exon 21 L858R substitution), treatment with an EGFR tyrosine kinase inhibitor (EGFR TKI; gefitinib, erlotinib or afatinib) represents standard first-line therapy. However, the clinical efficacy of these TKIs is ultimately limited by the development of acquired drug resistance such as by mutation of the gatekeeper T790 residue (T790M). To overcome this acquired drug resistance and develop novel anti-EGFR drugs, a cell-based assay system for EGFR TKI resistance mutant-selective inhibitors is required. We constructed a novel cell-based assay for the evaluation of EGFR TKI efficacy against EGFR mutation. To this end, we established non-tumorigenic immortalized breast epithelial cells that proliferate dependent on EGF (MCF 10A cells), which stably overexpress mutant EGFR. We found that the cells expressing EGFR containing the T790M mutation showed higher resistance against gefitinib, erlotinib and afatinib compared with cells expressing wild-type EGFR. In contrast, L858R mutant-expressing cells exhibited higher TKI sensitivity. The effect of T790M-selective inhibitors (osimertinib and rociletinib) on T790M mutant-expressing cells was significantly higher than gefitinib and erlotinib. Finally, when compared with commercially available isogenic MCF 10A cell lines carrying introduced mutations in EGFR, our EGFR mutant-overexpressing cells exhibited obviously higher responsiveness to EGFR TKIs depending on the underlying mutations because of the higher levels of EGFR phosphorylation in the EGFR mutant-overexpressing cells than in the isogenic cell lines. In conclusion, we successfully developed a novel cell-based assay for evaluating the efficacy of anti-EGFR drugs against EGFR mutation.

Clinical Implementation of Novel Targeted Therapeutics in Advanced Breast Cancer

The majority of advanced breast cancers have genetic alterations that are potentially targetable with drugs. Through initiatives such as The Cancer Genome Atlas (TCGA) and the International Cancer Genome Consortium (ICGC), data can be mined to provide context for next-generation sequencing (NGS) results in the landscape of advanced breast cancer. Therapies for targets other than estrogen receptor alpha (ER) and HER2, such as cyclin-dependent kinases CDK4 and CDK6, were recently approved based on efficacy in patient subpopulations, but no predictive biomarkers have been found, leaving clinicians to continue a trial-and-error approach with each patient. Next-generation sequencing identifies potentially actionable alterations in genes thought to be drivers in the cancerous process including phosphatidylinositol 3-kinase (PI3K), AKT, fibroblast growth factor receptors (FGFRs), and mutant HER2. Epigenetically directed and immunologic therapies have also shown promise for the treatment of breast cancer via histone deacetylases (HDAC) 1 and 3, programmed T cell death 1 (PD-1), and programmed T cell death ligand 1 (PD-L1). Identifying biomarkers to predict primary resistance in breast cancer will ultimately affect clinical decisions regarding adjuvant therapy in the first-line setting. However, the bulk of medical decision-making is currently made in the secondary resistance setting. Herein, we review the clinical potential of PI3K, AKT, FGFRs, mutant HER2, HDAC1/3, PD-1, and PD-L1 as therapeutic targets in breast cancer, focusing on the rationale for therapeutic development and the status of clinical testing. J. Cell. Biochem. 117: 2454-2463, 2016. © 2016 Wiley Periodicals, Inc.

Multi-OMIC profiling of survival and metabolic signaling networks in cells subjected to photodynamic therapy

Photodynamic therapy (PDT) is an established palliative treatment for perihilar cholangiocarcinoma that is clinically promising. However, tumors tend to regrow after PDT, which may result from the PDT-induced activation of survival pathways in sublethally afflicted tumor cells. In this study, tumor-comprising cells (i.e., vascular endothelial cells, macrophages, perihilar cholangiocarcinoma cells, and EGFR-overexpressing epidermoid cancer cells) were treated with the photosensitizer zinc phthalocyanine that was encapsulated in cationic liposomes (ZPCLs). The post-PDT survival pathways and metabolism were studied following sublethal (LC₅₀) and supralethal (LC₉₀) PDT. Sublethal PDT induced survival signaling in perihilar cholangiocarcinoma (SK-ChA-1) cells via mainly HIF-1-, NF-кB-, AP-1-, and heat shock factor (HSF)-mediated pathways. In contrast, supralethal PDT damage was associated with a dampened survival response. PDT-subjected SK-ChA-1 cells downregulated proteins associated with EGFR signaling, particularly at LC₉₀. PDT also affected various components of glycolysis and the tricarboxylic acid cycle as well as metabolites involved in redox signaling. In conclusion, sublethal PDT activates multiple pathways in tumor-associated cell types that transcriptionally regulate cell survival, proliferation, energy metabolism, detoxification, inflammation/angiogenesis, and metastasis. Accordingly, tumor cells sublethally afflicted by PDT are a major therapeutic culprit. Our multi-omic analysis further unveiled multiple druggable targets for pharmacological co-intervention.

Transtinib, a potent tyrosine kinase inhibitor inhibits L858R/T790M mutant NSCLC cell lines and xenografts

Non-small cell lung cancer (NSCLC) patients with activating epidermal growth factor receptor (EGFR) mutations initially respond well to the EGFR tyrosine kinase inhibitors (TKIs) erlotinib and gefitinib. However, clinical efficacy is limited by the development of resistance. In most cases, this resistance is in the form of the T790M mutation. Here, we report the design, synthesis and biochemical evaluation of a novel series of irreversible EGFR tyrosine kinase inhibitors (EGFR-TKIs) that are derived from the anilinoquinazoline scaffold. Guided by molecular modeling, this series of analogs was evolved to target a cysteine residue in the ATP binding site via covalent bond formation and to achieve high levels of anti-tumor activity in cell cultures and in xenografts. The most promising compound 13c ((E) –N - (4 - (4 - (3-fluorobenzyloxy) -3- chlorophenylamino) -7-ethoxyquinazolin-6-yl) -3- ((S) -pyrrolidin-2-yl)acrylamide, which we named Transtinib) displayed strong anti-proliferative activity against the H1975 and A431 cell lines with IC₅₀ values of 34 nM and 62 nM, respectively. In xenograft models, Transtinib significantly decreases tumor size for a prolonged period of time. These results suggest that Transtinib is a potential cancer therapeutic drug lead for the inhibition of mutant EGFR to overcome the development of resistance.

JAK2 inhibition sensitizes resistant EGFR-mutant lung adenocarcinoma to tyrosine kinase inhibitors

Lung adenocarcinomas with mutant epidermal growth factor receptor (EGFR) respond to EGFR-targeted tyrosine kinase inhibitors (TKIs), but resistance invariably occurs. We found that the Janus kinase (JAK)/signal transduction and activator of transcription 3 (STAT3) signaling pathway was aberrantly increased in TKI-resistant EGFR-mutant non-small cell lung cancer (NSCLC) cells. JAK2 inhibition restored sensitivity to the EGFR inhibitor erlotinib in TKI-resistant cell lines and xenograft models of EGFR-mutant TKI-resistant lung cancer. JAK2 inhibition uncoupled EGFR from its negative regulator, suppressor of cytokine signaling 5 (SOCS5), consequently increasing EGFR abundance and restoring the tumor cells' dependence on EGFR signaling. Furthermore, JAK2 inhibition led to heterodimerization of mutant and wild-type EGFR subunits, the activity of which was then blocked by TKIs. Our results reveal a mechanism whereby JAK2 inhibition overcomes acquired resistance to EGFR inhibitors and support the use of combination therapy with JAK and EGFR inhibitors for the treatment of EGFR-dependent NSCLC.

Three stories on Eph kinase inhibitors: From in silico discovery to in vivo validation

Several selective and potent EphB4 inhibitors have been discovered, optimized and biophysically characterized by our groups over the past years. On the outset of these discoveries high throughput docking techniques were applied. Herein, we review the optimization campaigns started from three of these hits (Xan-A1, Pyr-A1 and Qui-A1) with emphasis on their in depth in vitro and in vivo characterization, together with previously unpublished angiogenesis and fluorescence based assays.

Mechanisms of lapatinib resistance in HER2-driven breast cancer. Cancer Treat Rev. 2015;41:877-883. [PMID: 26276735 DOI: 10.1016/j.ctrv.2015.08.001]

Targeted therapies have been approved for various malignancies but the acquisition of resistance remains a substantial challenge in the clinical management of advanced cancers. Twenty-five per cent of breast cancers overexpress ErbB2/HER2, which confers a more aggressive phenotype and is associated with a poor prognosis. HER2-targeting therapies (trastuzumab, pertuzumab, TDM1 and lapatinib) are available, but a significant fraction of HER2-positive breast cancers eventually relapse or progress. This suggests that acquired or intrinsic resistance enables escape from HER2 inhibition. This review focuses on mechanisms of intrinsic/acquired resistance to lapatinib identified in preclinical and clinical studies. A better understanding of these mechanisms could lead to novel predictive markers of lapatinib response and to novel therapeutic strategies for breast cancer patients.

The small GTPase ADP-Ribosylation Factor 1 mediates the sensitivity of triple negative breast cancer cells to EGFR tyrosine kinase inhibitors

The clinical use of EGFR-targeted therapy, in triple negative breast cancer patients, has been limited by the development of resistance to these drugs. Although activated signaling molecules contribute to this process, the molecular mechanisms remain relatively unknown. We have previously reported that the small GTPase ADP-Ribosylation Factor 1 (ARF1) is highly expressed in invasive breast cancer cells and acts as a molecular switch to activate EGF-mediated responses. In this study, we aimed at defining whether the high expression of ARF1 limits sensitivity of these tumor cells to EGFR inhibitors, such as gefitinib. Here, we show that the knock down of ARF1 expression or activity decreased the dose and latency time required by tyrosine kinase inhibitors to induce cell death. This may be explained by the observation that the depletion of ARF1 suppressed gefitinib-mediated activation of key mediators of survival such as ERK1/2, AKT and Src, while enhancing cascades leading to apoptosis such as the p38MAPK and JNK pathways, modifying the Bax/Bcl2 ratio and cytochrome c release. In addition, inhibiting ARF1 expression and activation also results in an increase in gefitinib-mediated EGFR internalization and degradation further limiting the ability of this receptor to promote its effects. Interestingly, we observed that gefitinib treatment resulted in the enhanced activation of ARF1 by promoting its recruitment to the receptor AXL, an important mediator of EGFR inhibition suggesting that ARF1 may promote its pro-survival effects by coupling to alternative mitogenic receptors in conditions where the EGFR is inhibited. Together our results uncover a new role for ARF1 in mediating the sensitivity to EGFR inhibition and thus suggest that limiting the activation of this GTPase could improve the therapeutic efficacy of EGFR inhibitors.

Treating acquired resistance to EGFR-tyrosine kinase inhibitors:still a work in progress

While most patients with metastatic non-small cell lung cancer (NSCLC) containing sensitizing mutations in the epidermal growth factor receptor (EGFR) gene will achieve an objective response to EGFR tyrosine kinase inhibitors (TKIs) such as erlotinib or gefitinib, patients inevitably develop resistance to these agents. One of the strategies being tested to overcome acquired resistance to EGFR TKIs is the use of irreversible EGFR inhibitors such as afatinib. In the randomized phase 2b/3 LUX-Lung 1 trial in advanced NSCLC patients who progressed after at least 12 weeks of benefit from EGFR TKIs, afatinib failed to improve overall survival compared to placebo. Although the liberal entry criteria likely allowed the inclusion of some patients without true acquired resistance, the failure of this study calls into question the viability of irreversible EGFR inhibitors in this patient population.

Therapeutic advances in the treatment of polycystic kidney disease

The spectrum of polycystic kidney disease (PKD) comprises a family of inherited syndromes defined by renal cyst formation and growth, progressive renal function loss and variable extrarenal manifestations. The most common form, autosomal-dominant PKD is caused by mutations in one of two genes, PKD1 or PKD2. Recent developments in genomic and proteomic medicine have resulted in the discovery of novel genes implicated in the wide variety of less frequent, recessive PKD syndromes. Cysts are the disease, and overall cystic burden, measured by MRI as total kidney volume, is being established as the best available biomarker of disease progression. Current state-of-the-art therapy is aimed at quality treatment for chronic renal insufficiency and cyst-related complications. Recent therapeutic studies have focused on mechanisms reducing intracellular cyclic AMP levels, blocking the renin-angiotensin-aldosterone system and inhibiting the mTOR-signaling pathway. PKD therapies with vasopressin antagonists and somatostatin analogues result in the reduction of intracellular cAMP levels and have shown limited clinical success, but side effects are prominent. Similarly, mTOR pathway inhibition has not shown significant therapeutic benefits. While the HALT-PKD study will answer questions by the end of 2014 about the utility of renin-angiotensin-aldosterone system blockade and aggressive blood pressure control, the next generation of PKD therapy studies targeting proliferative mechanisms of cyst expansion are already under way. Advances in research on the molecular mechanisms of cystogenesis will help design novel targeted PKD therapies in the future.

Characterization of the activity of the PI3K/mTOR inhibitor XL765 (SAR245409) in tumor models with diverse genetic alterations affecting the PI3K pathway

Activation of the PI3K (phosphoinositide 3-kinase) pathway is a frequent occurrence in human tumors and is thought to promote growth, survival, and resistance to diverse therapies. Here, we report pharmacologic characterization of the pyridopyrimidinone derivative XL765 (SAR245409), a potent and highly selective pan inhibitor of class I PI3Ks (α, β, γ, and δ) with activity against mTOR. Broad kinase selectivity profiling of >130 protein kinases revealed that XL765 is highly selective for class I PI3Ks and mTOR over other kinases. In cellular assays, XL765 inhibits the formation of PIP(3) in the membrane, and inhibits phosphorylation of AKT, p70S6K, and S6 phosphorylation in multiple tumor cell lines with different genetic alterations affecting the PI3K pathway. In a panel of tumor cell lines, XL765 inhibits proliferation with a wide range of potencies, with evidence of an impact of genotype on sensitivity. In mouse xenograft models, oral administration of XL765 results in dose-dependent inhibition of phosphorylation of AKT, p70S6K, and S6 with a duration of action of approximately 24 hours. Repeat dose administration of XL765 results in significant tumor growth inhibition in multiple human xenograft models in nude mice that is associated with antiproliferative, antiangiogenic, and proapoptotic effects.

Second generation tyrosine kinase inhibitors for the treatment of metastatic non-small-cell lung cancer

Backgruond

Since their first description, activating epidermal growth factor receptor (EGFR) mutations identify a distinct clinical entity of patients with non-small-cell lung cancer (NSCLC).

Findings

New targeted therapies for molecularly selected NSCLC are changing the natural history of the disease, with results superior to standard chemotherapy as demonstrated in large phase III studies with first generation EGFR tyrosine kinase inhibitors (TKIs) erlotinib and gefitinib. However, after an initial response, all patients inevitably progress and several mechanisms including a secondary mutation in exon 20 of the EGFR gene (T790M) or MET or HER2 amplifications are responsible for acquired resistance (AR). In clinical practice few options are available for patients with AR, and several new agents or strategies are currently under investigation, including second generation TKIs.

Conclusions

Aim of the present review is to present available data on new EGFR-TKIs and to discuss how these agents could overcome AR to erlotinib or gefitinib.

Targeted therapies in development for non-small cell lung cancer

The iterative discovery in various malignancies during the past decades that a number of aberrant tumorigenic processes and signal transduction pathways are mediated by "druggable" protein kinases has led to a revolutionary change in drug development. In non-small cell lung cancer (NSCLC), the ErbB family of receptors (e.g., EGFR [epidermal growth factor receptor], HER2 [human epidermal growth factor receptor 2]), RAS (rat sarcoma gene), BRAF (v-raf murine sarcoma viral oncogene homolog B1), MAPK (mitogen-activated protein kinase) c-MET (c-mesenchymal-epithelial transition), FGFR (fibroblast growth factor receptor), DDR2 (discoidin domain receptor 2), PIK3CA (phosphatidylinositol-4,5-bisphosphate3-kinase, catalytic subunit alpha)), PTEN (phosphatase and tensin homolog), AKT (protein kinase B), ALK (anaplastic lym phoma kinase), RET (rearranged during transfection), ROS1 (reactive oxygen species 1) and EPH (erythropoietin-producing hepatoma) are key targets of various agents currently in clinical development. These oncogenic targets exert their selective growth advantage through various intercommunicating pathways, such as through RAS/RAF/MEK, phosphoinositide 3-kinase/AKT/mammalian target of rapamycin and SRC-signal transduction and transcription signaling. The recent clinical studies, EGFR tyrosine kinase inhibitors and crizotinib were considered as strongly effective targeted therapies in metastatic NSCLC. Currently, five molecular targeted agents were approved for treatment of advanced NSCLC: Gefitinib, erlotinib and afatinib for positive EGFR mutation, crizotinib for positive echinoderm microtubule-associated protein-like 4 (EML4)-ALK translocation and bevacizumab. Moreover, oncogenic mutant proteins are subject to regulation by protein trafficking pathways, specifically through the heat shock protein 90 system. Drug combinations affecting various nodes in these signaling and intracellular processes are predicted and demonstrated to be synergistic and advantageous in overcoming treatment resistance compared with monotherapy approaches. Understanding the role of the tumor microenvironment in the development and maintenance of the malignant phenotype provided additional therapeutic approaches as well. More recently, improved knowledge on tumor immunology has set the stage for promising immunotherapies in NSCLC. This review will focus on the rationale for the development of targeted therapies in NSCLC and the various strategies employed in preventing or overcoming the inevitable occurrence of treatment resistance.

Estrogen receptor-positive breast cancer molecular signatures and therapeutic potentials (Review)

In this review, the advances in the study of breast cancer molecular classifications and the molecular signatures of the luminal subtypes A and B of breast cancer were summarized. Effective clinical outcomes depend mainly on successful preclinical diagnosis and therapeutic decisions. Over the last few years, the ever-expanding investigations focusing on breast cancer diagnosis and the clinical trials have provided accumulating information on the molecular characteristics of breast cancer. Specifically, among the estrogen receptor (ER)-positive types of breast cancer, the luminal subtype A breast cancer has been shown to exhibit good clinical outcomes with endocrine therapy, whereas the luminal subtype B breast cancer represents the more complicated type, diagnostically as well as therapeutically. Furthermore, even in luminal subtype A breast cancer, the resistance to treatment has become the major limitation for endocrine-based therapy. Accumulating molecular data and further clinical trials may enable more accurate diagnostic and therapeutic decisions. The molecular signatures have emerged as a powerful tool for future diagnosis and therapeutic decisions, although currently available data are limited.

Nonsmall cell lung cancer therapy: insight into multitargeted small-molecule growth factor receptor inhibitors

To date, lung cancer is the leading cause of cancer-related death worldwide, among which nonsmall cell lung cancer (NSCLC) comprises about 85%. Taking into account the side effects of surgery, radiation, platinum-based doublet chemotherapy, and the growth self-sufficiency characteristic of cancer cells, drugs have been discovered toward growth factor receptor (GFR) to treat NSCLC. As expected, these drugs provide a greater benefit. To increase the efficacy of such growth factor receptor tyrosine kinase inhibitors (RTKIs), coinhibition of GFR signaling pathways and combination of inhibitors along with radiation or chemotherapy have drew intense insight. Although clinical trials about single-agent RTKIs or their combination strategies suggest their increase potency against cancer, they are not beyond adverse effects, and sometimes the effects are more deadly than chemotherapy. Nevertheless the hope for RTKIs may be proved true by further researches and digging deep into cancer therapeutics.

[Advanced research on T790M mutation in non-small cell lung cancer]

携带表皮生长因子受体（epidermal growth factor receptor, EGFR）基因活性突变的非小细胞肺癌（non-small cell lung cancer, NSCLC）晚期患者使用EGFR-受体酪氨酸激酶抑制剂（tyrosine kinase inhibitor, TKI）治疗后具有较好的临床获益，但大部分患者在使用该药治疗10个月后出现耐药现象。研究发现EGFR基因20号外显子T790M基因突变是导致EGFR-TKI耐药的最主要因素，但其作用机制至今未明。目前的研究结果显示T790M基因突变是一个独立的、好的预后因素，但其能否作为EGFR-TKI的疗效预测因子仍存在争议。近年来，针对NSCLC肿瘤中T790M基因突变的检测技术不断更新，针对T790M耐药的新的治疗策略也不断涌现。本文就NSCLC中T790M基因突变的耐药机制、临床意义、检测方法及应对策略等方面的最新研究进展进行综述。

The design, synthesis, and biological evaluation of potent receptor tyrosine kinase inhibitors

Variously substituted indolin-2-ones were synthesized and evaluated for activity against KDR, Flt-1, FGFR-1 and PDGFR. Extension at the 5-position of the oxindole ring with ethyl piperidine (compound 7i) proved to be the most beneficial for attaining both biochemical and cellular potencies. Further optimization of 7i to balance biochemical and cellular potencies with favorable ADME/ PK properties led to the identification of 8h, a compound with a clean CYP profile, acceptable pharmacokinetic and toxicity profiles, and robust efficacy in multiple xenograft tumor models.

EGFR-mutant lung adenocarcinomas treated first-line with the novel EGFR inhibitor, XL647, can subsequently retain moderate sensitivity to erlotinib

INTRODUCTION

EGFR-mutant lung cancers are sensitive to EGFR tyrosine kinase inhibitors (TKIs). Unfortunately, they develop resistance, often due to acquisition of a second-site mutation (T790M). Current EGFR TKIs select for T790M in preclinical models of acquired resistance. We explored whether all EGFR TKIs similarly select for the T790M mutation using data from early clinical trials and established in vitro models of acquired resistance.

METHODS

We analyzed the clinical characteristics of eight patients with metastatic EGFR-mutant lung adenocarcinoma who were treated first-line with XL647 and then progressed. XL647 is an ATP-competitive inhibitor of EGFR, HER2, KDR, and EPHB4. Additional molecular preclinical studies were performed to characterize resistance.

RESULTS

Four patients displayed confirmed partial responses (PRs), three patients had unconfirmed PRs, and one patient displayed stable disease. Only one of five patients' tumor samples available for analysis after disease progression harbored the T790M mutation. Eight patients subsequently received erlotinib, with (n = 3) or without (n = 5) chemotherapy. Three of five patients treated with single-agent erlotinib derived additional benefit, staying on drug up to 9 months. EGFR-mutant PC-9 cells with acquired resistance to XL647 did not harbor the T790M mutation, displayed a distinct mRNA profile from PC-9 cells with T790M-mediated resistance, and were moderately sensitive to erlotinib in growth inhibition assays. Crystal structure analyses of XL647/EGFR T790M did not reveal a different binding mode from that of erlotinib.

CONCLUSIONS

The findings of this exploratory study suggest that different EGFR TKIs may select for distinct mechanisms of resistance. These results raise the possibility that different EGFR TKIs could be sequentially used to improve outcomes in patients with EGFR-mutant lung cancer. Further work investigating this hypothesis is warranted.

XL647--a multitargeted tyrosine kinase inhibitor: results of a phase II study in subjects with non-small cell lung cancer who have progressed after responding to treatment with either gefitinib or erlotinib. J Thorac Oncol. 2012;7:219-226. [PMID: 22011666 DOI: 10.1097/jto.0b013e31822eebf9]

INTRODUCTION

Although patients with non-small cell lung cancer (NSCLC) whose tumors harbor epidermal growth factor receptor (EGFR) activating mutations commonly experience significant regressions when treated with erlotinib or gefitinib, they uniformly develop resistance to these agents. The secondary EGFR T790M mutation is found in 50% of patients with acquired resistance. Herein, we studied XL647, an oral small molecule inhibitor of multiple receptor tyrosine kinases, including EGFR, VEGFR2, HER2, and EphB4, in NSCLC patients known or suspected of having tumors harboring T790M.

METHODS

Eligible patients included those with relapsed or recurrent advanced NSCLC who progressed after ≥12 weeks of stable disease or response to erlotinib or gefitinib and/or those patients with a documented EGFR T790M. XL647 300 mg was administered once daily. The primary end point was objective response rate. Pretreatment plasma samples were collected for mutation testing of circulating tumor DNA.

RESULTS

Forty-one patients were enrolled; 33 were evaluable for efficacy. One partial response was observed (response rate 3% and 90% confidence interval, 0% to 14%). Of patients whose tumors harbored T790M, 67% (8/12) had progression of disease as best response compared with 14% (3/21) of those without this mutation. Plasma samples from 40 patients were available for mutation testing, 14 (35%) of which were found to have EGFR mutations.

CONCLUSIONS

The 3% response rate observed did not meet the prespecified threshold to recommend further study of XL647 in patients who develop acquired resistance to erlotinib or gefitinib. Patients with T790M had a significantly worse progression-free survival.

In situ kinase profiling reveals functionally relevant properties of native kinases

Protein kinases are intensely studied mediators of cellular signaling, yet important questions remain regarding their regulation and in vivo properties. Here, we use a probe-based chemoprotemics platform to profile several well studied kinase inhibitors against >200 kinases in native cell proteomes and reveal biological targets for some of these inhibitors. Several striking differences were identified between native and recombinant kinase inhibitory profiles, in particular, for the Raf kinases. The native kinase binding profiles presented here closely mirror the cellular activity of these inhibitors, even when the inhibition profiles differ dramatically from recombinant assay results. Additionally, Raf activation events could be detected on live cell treatment with inhibitors. These studies highlight the complexities of protein kinase behavior in the cellular context and demonstrate that profiling with only recombinant/purified enzymes can be misleading.

A microRNA gene expression signature predicts response to erlotinib in epithelial cancer cell lines and targets EMT. Br J Cancer. 2012;106:148-156. [PMID: 22045191 PMCID: PMC3251842 DOI: 10.1038/bjc.2011.465]

Background:

Treatment with epidermal growth factor receptor (EGFR) inhibitors can result in clinical response in non-small-cell lung cancer (NSCLC) and pancreatic ductal adenocarcinoma (PDAC) for some unselected patients. EGFR and KRAS mutation status, amplification of EGFR, or gene expression predictors of response can forecast sensitivity to EGFR inhibition.

Methods:

Using an NSCLC cell line model system, we identified and characterised microRNA (miRNA) gene expression that predicts response to EGFR inhibition.

Results:

Expression of 13 miRNA genes predicts response to EGFR inhibition in cancer cell lines and tumours, and discriminates primary from metastatic tumours. Signature genes target proteins that are enriched for epithelial-to-mesenchymal transition (EMT) genes. Epithelial-to-mesenchymal transition predicts EGFR inhibitor resistance and metastatic behaviour. The EMT transcription factor, ZEB1, shows altered expression in erlotinib-sensitive NSCLC and PDAC, where many signature miRNA genes are upregulated. Ectopic expression of mir-200c alters expression of EMT proteins, sensitivity to erlotinib, and migration in lung cells. Treatment with TGFβ1 changes expression of signature miRNA and EMT proteins and modulates migration in lung cells.

Conclusion:

From these data, we hypothesise that the tumour microenvironment elicits TGFβ1 and stimulates a miRNA gene expression program that induces resistance to anti-EGFR therapy and drives lung tumour cells to EMT, invasion, and metastasis.

Targeting Eph receptors with peptides and small molecules: progress and challenges

The Eph receptors are a large family of receptor tyrosine kinases. Their kinase activity and downstream signaling ability are stimulated by the binding of cell surface-associated ligands, the ephrins. The ensuing signals are bidirectional because the ephrins can also transduce signals (known as reverse signals) following their interaction with Eph receptors. The ephrin-binding pocket in the extracellular N-terminal domain of the Eph receptors and the ATP-binding pocket in the intracellular kinase domain represent potential binding sites for peptides and small molecules. Indeed, a number of peptides and chemical compounds that target Eph receptors and inhibit ephrin binding or kinase activity have been identified. These molecules show promise as probes to study Eph receptor/ephrin biology, as lead compounds for drug development, and as targeting agents to deliver drugs or imaging agents to tumors. Current challenges are to find (1) small molecules that inhibit Eph receptor-ephrin interactions with high binding affinity and good lead-like properties and (2) selective kinase inhibitors that preferentially target the Eph receptor family or subsets of Eph receptors. Strategies that could also be explored include targeting additional Eph receptor interfaces and the ephrin ligands.

Computational modeling of allosteric communication reveals organizing principles of mutation-induced signaling in ABL and EGFR kinases

The emerging structural information about allosteric kinase complexes and the growing number of allosteric inhibitors call for a systematic strategy to delineate and classify mechanisms of allosteric regulation and long-range communication that control kinase activity. In this work, we have investigated mechanistic aspects of long-range communications in ABL and EGFR kinases based on the results of multiscale simulations of regulatory complexes and computational modeling of signal propagation in proteins. These approaches have been systematically employed to elucidate organizing molecular principles of allosteric signaling in the ABL and EGFR multi-domain regulatory complexes and analyze allosteric signatures of the gate-keeper cancer mutations. We have presented evidence that mechanisms of allosteric activation may have universally evolved in the ABL and EGFR regulatory complexes as a product of a functional cross-talk between the organizing αF-helix and conformationally adaptive αI-helix and αC-helix. These structural elements form a dynamic network of efficiently communicated clusters that may control the long-range interdomain coupling and allosteric activation. The results of this study have unveiled a unifying effect of the gate-keeper cancer mutations as catalysts of kinase activation, leading to the enhanced long-range communication among allosterically coupled segments and stabilization of the active kinase form. The results of this study can reconcile recent experimental studies of allosteric inhibition and long-range cooperativity between binding sites in protein kinases. The presented study offers a novel molecular insight into mechanistic aspects of allosteric kinase signaling and provides a quantitative picture of activation mechanisms in protein kinases at the atomic level.

Despite recent progress in computational and experimental studies of dynamic regulation in protein kinases, a mechanistic understanding of long-range communication and mechanisms of mutation-induced signaling controlling kinase activity remains largely qualitative. In this study, we have performed a systematic modeling and analysis of allosteric activation in ABL and EGFR kinases at the increasing level of complexity - from catalytic domain to multi-domain regulatory complexes. The results of this study have revealed organizing structural and mechanistic principles of allosteric signaling in protein kinases. Although activation mechanisms in ABL and EGFR kinases have evolved through acquisition of structurally different regulatory complexes, we have found that long-range interdomain communication between common functional segments (αF-helix and αC-helix) may be important for allosteric activation. The results of study have revealed molecular signatures of activating cancer mutations and have shed the light on general mechanistic aspects of mutation-induced signaling in protein kinases. An advanced understanding and further characterization of molecular signatures of kinase mutations may aid in a better rationalization of mutational effects on clinical outcomes and facilitate molecular-based therapeutic strategies to combat kinase mutation-dependent tumorigenesis.

Phase I study of irinotecan and gefitinib in patients with gefitinib treatment failure for non-small cell lung cancer

Background:

Currently, no effective treatments exist for non-small cell lung cancer (NSCLC) after failure of gefitinib therapy. Pre-clinical studies have demonstrated that gefitinib-resistant NSCLC cells are more sensitive to irinotecan than parental cells, and that combined administration of irinotecan and gefitinib has a synergistic additive effect. We conducted a phase I study to evaluate the combination of irinotecan and gefitinib as a therapeutic option for NSCLC patients with progressive disease (PD) after initial gefitinib treatment.

Methods:

Eligibility criteria included histologically confirmed NSCLC, age range of 20–74 years, refractory to or relapsed after gefitinib treatment, one or more previous chemotherapy regimens, Eastern Cooperative Oncology Group performance status 0–2, adequate organ function, and informed consent. Patients were treated with irinotecan on days 1 and 15, and treated daily with gefitinib from day 2 every 4 weeks. The treatment was continued until disease progression. The gefitinib dose was fixed at 250 mg. Irinotecan dosing started at 50 mg m⁻² and was escalated in patients by 25 mg m⁻² increments up to a maximum dose of 150 mg m⁻².

Results:

Twenty-seven patients were enrolled: male/female=14/13; median age=60 (45–75); histology, adenocarcinoma/non-adenocarcinoma=25/2; performance status 0–1/2=19/8; previous response to gefitinib, partial response/stable disease/PD=21/2/4. Dose-limiting toxicities were observed in 2 patients at level 3. Maximum tolerated dose was not determined, and the full dose of irinotecan could be combined with the full dose of gefitinib. The disease control rate (DCR) and response rate (RR) were 69.2 and 26.9%, respectively. For 12 patients at level 5 (the recommended phase II dose), the DCR and RR were 75.0% and 41.7%, respectively. The median treatment cycles were 4; median time to treatment failure, 57 days (95% confidence interval (CI), 32–82 days); median overall survival, 244 days (95% CI, 185–303 days); and 1-year survival rate, 32.6%.

Conclusion:

The combination of irinotecan and gefitinib was well tolerated and potentially beneficial for NSCLC patients failing initial gefitinib monotherapy.

Targeted therapies for advanced non-small-cell lung cancer: current status and future implications

Lung cancer remains the leading cause of malignancy-related mortality worldwide, with over one million cases diagnosed yearly. Non-small-cell lung cancer (NSCLC) accounts for >80% of all lung cancers. Because lung cancer is typically diagnosed at an advanced stage, chemotherapy (CT) is the mainstay of management. Conventional treatment of NSCLC has apparently reached a plateau of effectiveness in improving survival of patients, and treatment outcomes must still be considered disappointing. Hence, considerable efforts have been made in order to identify novel targeted agents that interfere with other dysregulated pathways in advanced NSCLC patients. In order to further improve the results of targeted therapy, we should not forget that lung cancer is a heterogeneous disease with multiple mutations, and it is unlikely that any single signaling pathway drives the oncogenic behaviour of all tumours. The relative failure of some targeted therapies may be a result of multilevel cross-stimulation among the targets of the new biological agents along several pathways of signal transduction that lead to neoplastic events. Thus, blocking only one of these pathways allows others to act as salvage or escape mechanisms for cancer cells. We summarize the most promising research approaches to the treatment of NSCLC, with particular attention to drugs with multiple targets or combining targeted therapies.

Vascular endothelial growth factor receptor tyrosine kinase inhibitors in non-small-cell lung cancer

Angiogenesis is essential for cancer growth and progression. Vascular endothelial growth factor (VEGF) plays a crucial role in angiogenesis. The addition of bevacizumab, an antibody to vascular endothelial growth factor (VEGF), to paclitaxel and carboplatin improves survival compared with chemotherapy alone in patients with previously untreated metastatic nonsquamous non-small-cell lung cancer (NSCLC). Vascular endothelial growth factor receptor tyrosine kinase inhibitors (VEGFR TKIs) are a new class of drugs that target the TK domain of the VEGF receptors. To evaluate the role of this class of agents in the treatment of NSCLC, some phase II and phase III studies using these agents alone or in combination with other agents have been completed. This review summarizes the currently available data on VEGFR TKIs in the treatment of 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.

Targeting epidermal growth factor receptor in the treatment of non-small-cell lung cancer

IMPORTANCE OF THE FIELD

The management of non-small-cell lung cancer (NSCLC) has undergone a paradigm shift in the last decade, with the survival advantage demonstrated by the incorporation of anti-epidermal growth factor receptor (EGFR) agents to the standard treatment of advanced/metastatic NSCLC.

AREAS COVERED IN THIS REVIEW

We review the existing data regarding the distinct anti-EGFR agents in the NSCLC treatment and the potential role of the investigated biomarkers in the clinical outcome.

WHAT THE READER WILL GAIN

Tyrosine kinase inhibitors have been used in first-line, second-line and more settings with extremely good results in a subgroup of patients. Cetuximab remains the only anti-EGFR monoclonal antibody to show survival benefit when combined with a cytotoxic agent in the front-line setting. Anti-EGFR treatment is associated with a dramatic clinical benefit in a subgroup of patients, emphasizing the importance of customizing treatment. Several biomarkers have been investigated for their predictive or prognostic value. Validation of identification of biomarkers remains a focus of intense research that may ultimately guide therapeutic decision making, as none of these is considered ideal to discriminate responding from non-responding patients. However, the current evidence of the EGFR mutation analysis from a recent randomised trial suggests that EGFR mutation analysis is quite a good predictive marker for responsiveness to anti-EGFR TKIs. Moreover, the identification of surrogate markers to indicate optimal activity of the anti-EGFR agent is also needed. This review article provides data from large clinical trials using anti-EGFR agents and correlates these results with the tested biomarkers.

TAKE HOME MESSAGE

EGFR inhibition has shown very encouraging results and has improved the outcome of the NSCLC treatment. However, a plateau of significant clinical benefit seems to have been reached and we believe that the time to move away from the traditional treatment approach to more individualizing therapies has come.

Rational, biologically based treatment of EGFR-mutant non-small-cell lung cancer

Epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancer (NSCLC) was first recognized in 2004 as a distinct, clinically relevant molecular subset of lung cancer. The disease has been the subject of intensive research at both the basic scientific and clinical levels, becoming a paradigm for how to understand and treat oncogene-driven carcinomas. Although patients with EGFR-mutant tumours have increased sensitivity to tyrosine kinase inhibitors (TKIs), primary and acquired resistance to these agents remains a major clinical problem. This Review summarizes recent developments aimed at treating and ultimately curing the disease.

Targeting lymphatic vessel functions through tyrosine kinases

The lymphatic vascular system is actively involved in tissue fluid homeostasis, immune surveillance and fatty acid transport. Pathological conditions can arise from injury to the lymphatics, or they can be recruited in the context of cancer to facilitate metastasis. Protein tyrosine kinases are central players in signal transduction networks and regulation of cell behavior. In the lymphatic endothelium, tyrosine kinases are involved in processes such as the maintenance of existing lymphatic vessels, growth and maturation of new vessels and modulation of their identity and function. As such, they are attractive targets for both existing inhibitors and the development of new inhibitors which affect lymphangiogenesis in pathological states such as cancer. RNAi screening provides an opportunity to identify the functional role of tyrosine kinases in the lymphatics. This review will discuss the role of tyrosine kinases in lymphatic biology and the potential use of inhibitors for anti-lymphangiogenic therapy.

Targeted therapy for nonsmall cell lung cancer: focusing on angiogenesis, the epidermal growth factor receptor and multikinase inhibitors

Chemotherapy used to be the only available option to fight advanced nonsmall cell lung cancer. Platinum-based medication combined with taxanes, vinca alkaloids, and antimetabolites improved patient survival rates. Unfortunately, neoplasmatic diseases remain a global killer because chemotherapy benefits have reached a plateau and most patients are diagnosed at the metastatic stage. The urgent need for therapeutic agents, along with advances in the knowledge of the molecular events of oncogenesis, has resulted in the development of medication that specifically targets processes and pathways critical for tumor growth, such as angiogenesis and the epidermal growth factor receptor. Initially, inhibiting these pathways managed to prolong patient survival, although not to the extent desired. Moreover, targeted therapy combined with conventional cytotoxic agents has shown no superiority to chemotherapy alone in terms of patient survival. Hence, numerous multidynamic agents have appeared in the hope that they might help fight nonsmall cell lung cancer. However, no group of patients who will hopefully gain maximum benefit from such interventions has been clearly identified yet. This paper presents current evidence with regard to such novel agents and angiogenesis and epidermal growth factor inhibitors.