Tyrosine kinase inhibitors in cancers: Treatment optimization - Part I

A multitude of TKI has been developed and approved targeting various oncogenetic alterations. While these have provided improvements in efficacy compared with conventional chemotherapies, resistance to targeted therapies occurs. Mutations in the kinase domain result in the inability of TKI to inactivate the protein kinase. Also, gene amplification, increased protein expression and downstream activation or bypassing of signalling pathways are commonly reported mechanisms of resistance. Improved understanding of mechanisms involved in TKI resistance has resulted in the development of new generations of targeted agents. In a race against time, the search for new, more potent and efficient drugs, and/or combinations of drugs, remains necessary as new resistance mechanisms to the latest generation of TKI emerge. This review examines the various generations of TKI approved to date and their common mechanisms of resistance, focusing on TKI targeting BCR-ABL, epidermal growth factor receptor, anaplastic lymphoma kinase and BRAF/MEK tyrosine kinases.

A Phase 1 study of gefitinib combined with durvalumab in EGFR TKI-naive patients with EGFR mutation-positive locally advanced/metastatic non-small-cell lung cancer

BACKGROUND

EGFR tyrosine kinase inhibitors (TKIs) induce cytolysis and release of tumour proteins, which can stimulate antigen-specific T cells. The safety and efficacy of durvalumab and gefitinib in combination for TKI-naive patients with advanced EGFRm NSCLC was evaluated.

METHODS

This Phase 1 open-label, multicentre trial (NCT02088112) was conducted in 56 patients with NSCLC. Dose expansion permitted TKI-naive patients, primarily with activating L858R or Ex19del EGFRm. Arms 1 + 1a received concurrent therapy; Arm 2 received 4 weeks of gefitinib induction followed by concurrent therapy.

RESULTS

From dose escalation, the recommended dose of durvalumab was 10 mg/kg Q2W with 250 mg QD gefitinib. Pharmacokinetics were as expected, consistent with inhibition of soluble PD-L1 and no treatment-emergent immunogenicity. In dose expansion, 35% of patients had elevated liver enzymes leading to drug discontinuation. In Arms 1 + 1a, objective response rate was 63.3% (95% CI: 43.9-80.1), median progression-free survival (PFS) was 10.1 months (95% CI: 5.5-15.2) and median response duration was 9.2 months (95% CI: 3.7-14.0).

CONCLUSIONS

Durvalumab and gefitinib in combination had higher toxicity than either agent alone. No significant increase in PFS was detected compared with historical controls. Therefore, concurrent PD-L1 inhibitors with gefitinib should be generally avoided in TKI-naive patients with EGFRm NSCLC.

Future directions and management of liquid biopsy in non-small cell lung cancer

Lung cancer represents the world’s most common cause of cancer death. In recent years, we moved from a generic therapeutic strategy to a personalized approach, based on the molecular characterization of the tumor. In this view, liquid biopsy is becoming an important tool for assessing the progress or onset of lung disease. Liquid biopsy is a non-invasive procedure able to isolate circulating tumor cells, tumor educated platelets, exosomes and free circulating tumor DNA from body fluids. The characterization of these liquid biomarkers can help to choose the therapeutic strategy for each different case. In this review, the authors will analyze the main aspects of lung cancer and the applications currently in use focusing on the benefits associated with this approach for predicting the prognosis and monitoring the clinical conditions of lung cancer disease.

Recent updates on the resistance mechanisms to epidermal growth factor receptor tyrosine kinase inhibitors and resistance reversion strategies in lung cancer

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have led to a substantial improvement in the prognosis of lung cancer patients by explicitly targeting the activating mutations within the EGFR. Initially, patients harboring tumors with EGFR mutations show progression-free survival and improvement in the response rates toward all-generation EGFR-TKIs; however, these agents fail to deliver the intended results in the long-term due to drug resistance. Therefore, it is necessary to recognize specific cardinal mechanisms that regulate the resistance phenomenon. Understanding the intricate mechanisms underlying EGFR-TKIs resistance in lung cancer could provide cognizance for more advanced targeted therapeutics. The present review features insights into current updates on the discrete mechanisms, including secondary or tertiary mutations, parallel and downstream signaling pathways, acquiring an epithelial-to-mesenchymal transition (EMT) signature, microRNAs (miRNAs), and epigenetic alterations, which lead to intrinsic and acquired resistance against EGFR-TKIs in lung cancer. In addition, this paper also reviews current possible strategies to overcome this issue using combination treatment of recently developed MET inhibitors, allosteric inhibitors or immunotherapies, transformation of EMT, targeting miRNAs, and epigenetic alterations in intrinsic and acquired EGFR-TKIs resistant lung cancer. In conclusion, multiple factors are responsible for intrinsic and acquired resistance to EGFR-TKIs and understanding of the detailed molecular mechanisms, and recent advancements in pharmacological studies are needed to develop new strategies to overcome intrinsic and acquired EGFR-TKIs resistance in lung cancer.

Mechanisms of acquired resistance to first- and second-generation EGFR tyrosine kinase inhibitors

Patients with non-small-cell lung cancer (NSCLC) whose tumours harbour activating mutations within the epidermal growth factor receptor (EGFR) frequently derive significant clinical and radiographic benefits from treatment with EGFR tyrosine kinase inhibitors (TKIs). As such, prospective identification of EGFR mutations is now the standard of care worldwide. However, acquired therapeutic resistance to these agents invariably develops. Over the past 10 years, great strides have been made in defining the molecular mechanisms of EGFR TKI resistance in an effort to design rational strategies to overcome this acquired drug resistance. Approximately 60% of patients with acquired resistance to the EGFR TKIs (erlotinib, gefitinib, and afatinib) develop a new mutation within the drug target. This mutation-T790M-has been shown to alter drug binding and enzymatic activity of the mutant EGF receptor. Less common mechanisms of acquired resistance include MET amplification, ERBB2 amplification, transformation to small-cell lung cancer, and others. Here, we present a condensed overview of the literature on EGFR-mutant NSCLC, paying particular attention to mechanisms of drug resistance, recent clinical trial results, and novel strategies for identifying and confronting drug resistance, while also striving to identify gaps in current knowledge. These advances are rapidly altering the treatment landscape for EGFR-mutant NSCLC, expanding the armamentarium of available therapies to maximize patient benefit.

Multi-disciplinary proactive follow-up algorithm for patients with advanced NSCLC receiving afatinib

PURPOSE

Afatinib is a standard first-line therapy for advanced EGFR-positive NSCLC. We implemented a pharmacist-led proactive follow-up algorithm to identify and manage early afatinib-related adverse events (AEs).

METHODS

We conducted a retrospective chart review of all patients treated with afatinib after implementation of the algorithm at the Sunnybrook Odette Cancer Centre (Toronto, ON, Canada) from April 1, 2015 to July 31, 2016. Our in-house algorithm involved consultations in person and proactive pharmacist-led callbacks on days 5, 10, and 17. All AEs were graded and documented in real time and management based on toxicity grade was standardized. This study evaluated the impact of our algorithm on real-world AEs.

RESULTS AND DISCUSSION

Thirty-three patients were identified and reviewed. Median follow-up was 248 days. All patients experienced at least one drug-related AE; 18.2% were grade 3/4. The most common AEs were diarrhea 87.9%, rash 81.8%, stomatitis 57.6%, and paronychia 45.5%. Median dose of afatinib was 40 mg daily; 51.5% of patients had ≥ 1 dose reduction and 6.3% discontinued afatinib due to AEs. Proactive calls by the pharmacist identified 36.5% of all drug-related AEs, 33.3% of grade 3/4 AEs, 58.1% of first drug-related AEs and identified two patients that were non-compliant. Only 3.2% of AEs were identified by an emergency room/urgent clinic visit.

CONCLUSIONS

This proactive multi-disciplinary AE management algorithm resulted in a low rate of urgent assessments and discontinuation due to toxicity while maintaining afatinib at ideal dose, thus providing a useful tool for centers prescribing afatinib.

The prevalence of EGFR mutation in patients with non-small cell lung cancer: a systematic review and meta-analysis

OBJECTIVES

Estimate the epidermal growth factor receptor (EGFR) mutation prevalence in all non-small cell lung cancer (NSCLC) patients and patient subgroups.

RESULTS

A total of 456 studies were included, reporting 30,466 patients with EGFR mutation among 115,815 NSCLC patients. The overall pooled prevalence for EGFR mutations was 32.3% (95% CI 30.9% to 33.7%), ranging from 38.4% (95% CI: 36.5% to 40.3%) in China to 14.1% (95% CI: 12.7% to 15.5%) in Europe. The pooled prevalence of EGFR mutation was higher in females (females vs. males: 43.7% vs. 24.0%; OR: 2.7, 95% CI: 2.5 to 2.9), non-smokers (non-smokers vs. past or current smokers: 49.3% vs. 21.5%; OR: 3.7, 95% CI: 3.4 to 4.0), and patients with adenocarcinoma (adenocarcinoma vs. non-adenocarcinoma: 38.0% vs. 11.7%; OR: 4.1, 95% CI: 3.6 to 4.8).

MATERIALS AND METHODS

PubMed, EMBASE, and the Cochrane Library were searched to June 2013. Eligible studies reported EGFR mutation prevalence and the association with at least one of the following factors: gender, smoking status and histology. Random-effects models were used to pool EGFR mutation prevalence data.

CONCLUSION

This study provides the exact prevalence of EGFR mutations in different countries and NSCLC patient subgroups.

Theoretical method for evaluation of therapeutic effects and adverse effects of epidermal growth factor receptor tyrosine kinase inhibitors in clinical treatment

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are used for non-small cell lung cancer patients with an EGFR gene mutation. However, skin disorders are known as adverse events. In the present study, we investigated whether EGFR-TK occupancy is useful as an index for assessing clinical efficacy and adverse events for the proper use and development of EGFR-TKIs. Average binding occupancies (Φ _ss) of EGFR-TKIs, gefitinib and erlotinib, for the EGFR-TK of cancer or skin cells were calculated. The relationships of Φ _ss with response rate (RR) or frequency of rash were analyzed using the ternary complex model. Then, the relationships between the dose of EGFR-TKIs and RR or frequency of rash were examined. Gefitinib showed a greater difference for Φ _ss value for both wild-type and mutant EGFR as compared to erlotinib at usual dose. The RR increased in a nonlinear manner rapidly rising when Φ _ss exceeded 95%. It was thought that a very high Φ _ss value might be needed to obtain the therapeutic effect of EGFR-TKIs. Meanwhile, the frequency of rash increased in a linear manner along with elevation of Φ _ss. It was shown that the K _d ratio (K _d for mutant/K _d for wild type) was less than 0.001, when the high RR and low frequency of rash were obtained simultaneously. The results showed that the therapeutic effects and skin disorder can be assessed by using Φ _ss. Furthermore, it is likely that a proper choice of drug and dose can be made by using Φ _ss in EGFR-TKI therapy.

EML4-ALK Fusion Detected by RT-PCR Confers Similar Response to Crizotinib as Detected by FISH in Patients with Advanced Non-Small-Cell Lung Cancer

INTRODUCTION

Reverse transcriptase polymerase chain reaction (RT-PCR) assay has been proved to have high sensitivity and specificity to detect anaplastic lymphoma kinase (ALK) rearrangements. The aim of this study was to investigate the response to crizotinib in patients of advanced non-small-cell lung cancer (NSCLC) with ALK rearrangements detected by RT-PCR.

METHODS

Only patients with advanced NSCLC who had their ALK rearrangement status detected by RT-PCR were included in this analysis. The utility of RT-PCR and fluorescence in situ hybridization (FISH) assay were compared in patients who were treated with crizotinib based on their positive ALK rearrangements.

RESULTS

One thousand ten patients were included in this study. Among them, 104 patients were ALK RT-PCR positive and 53 of them received crizotinib treatment. Among 255 tumors simultaneously analyzed by FISH and RT-PCR, the latter successfully detected all the 25 tumors with arrangements, including two cases that were missed by FISH. The overall response rate and median progression-free survival of the 53 patients with ALK rearrangements who received crizotinib treatment were 60.4% (95% confidence interval [CI], 47.2-73.6) and 8.4 months (95% CI, 6.75-10.05), respectively, which were similar to the 21 patients detected by FISH with overall response rate of 57.1% (95% CI, 33.3-76.2; p = 0.799) and median progression-free survival of 7.4 months (95% CI, 4.43-10.38; p = 0.833) after crizotinib treatment. Interestingly, there were two patients responded to crizotinib had their ALK rearrangement detected by RT-PCR but not FISH.

CONCLUSIONS

RT-PCR should be considered as an alternative/supplemental approach to detect ALK fusion oncogene in NSCLC patients who might benefit from crizotinib treatment.

Effect of hydrothorax EGFR gene mutation and EGFR-TKI targeted therapy on advanced non-small cell lung cancer patients

Lung cancer is a malignancy with the highest incidence of morbidity and mortality worldwide. The lack of effective detection methods leads to the ineffectiveness of convetional therapy. The aim of the current study was to analyze the hydrothorax epidermal growth factor receptor (EGFR) mutation in patients with advanced non-small lung cancer (NSCLC) and malignant pleural effusion. A new method for clinical treatment was developed through a comparison of the difference of EGFR tyrosine kinase inhibitor (EGFR-TKI)-targeted therapy. Between January 2013 and January 2015, 68 cases diagnosed with advanced non-small lung cancer and malignant pleural effusion, were enrolled in the study. Previous first-line chemotherapeutic treatment schemes had been unsuccessful. EGFR 19 and EGFR 21 sites were detected for all the patients. Platinum-based drugs were provided for patients with wild-type EGFR. These patients served as the control group and underwent four cycles of treatments, with each cycle lasting 3 weeks. TKI medicine Gefitinib (Iressa™) was administered to patients with mutant EGFR tid, po, for a duration of 4-8 months. These patients served as the experimental group. There were 41 cases of EGFR mutations, of which 13 cases had EGFR 19 site mutations, 16 cases EGFR 21 site mutations, and the remaining 12 cases had 2 site mutations. EGFR mutations were not significant for gender, age, tumor type, stage and diameter (P>0.05). The results showed that the six-month survival rate, progression-free survival time (PFS), objective response rate (RP) and disease control rate (DCR) in the experimental group were higher than those in the control group. The drug side-effects in the experimental group indicated no statistical differences compared to the control group (P>0.05). The incidence of EGFR mutation was higher in patients with advanced non-small lung cancer and malignant pleural effusion. Targeted therapy improved the survival rate and was deemed to be a safe and effective method for patients with EGFR mutations.

Feasibility of cytological specimens for ALK fusion detection in patients with advanced NSCLC using the method of RT-PCR

OBJECTIVES

Histological tissues are preferred for anaplastic lymphoma kinase (ALK) fusion detection in non-small cell lung cancer (NSCLC). The aim of this study was to evaluate the feasibility of cytological sample as an alternative specimen for ALK fusion testing in patients with advanced NSCLC.

MATERIALS AND METHODS

Advanced NSCLC patients with cytological specimens or tumor tissue who had their ALK fusion status detected by the method of reverse transcriptase polymerase chain reaction (RT-PCR) in Shanghai Pulmonary Hospital, Tongji University were included into this study. The efficacy was evaluated in those with ALK fusion positive and received the therapy of crizotinib.

RESULTS

1274 patients were included in this study. Among them, 108 patients were ALK RT-PCR positive and 69 of them received crizotinib treatment. Among 1002 patients with cytological specimens, the average concentration of RNA extracted from cytological specimens was 60.99 ng/μl (95% confidence interval [CI], 55.56-66.60) and the incidence rate of ALK fusion was 8.3% (83/1002), which were similar to 63.16 ng/μl (95% CI, 51.88-76.34) (p=0.727) and 9.2% (25/272, p=0.624) in 272 patients with tumor tissue. Also, there were no statistically significant differences regarding to the objective response rate (ORR) (62.0% vs. 42.1%, p=0.177) and the median progression free survival (mPFS) [8.6 months (95% CI 7.30-9.84) vs. 7.0 months (95% CI 4.54-9.47), p=0.736] in patients of cytological group and tissue group after the treatment of crizotinib.

CONCLUSION

Cytological specimens showed a high feasibility to detect ALK fusion status, which could be regarded as alternative samples for ALK fusion detection by the method of RT-PCR in patients with advanced NSCLC.

Subsequent treatment choices for patients with acquired resistance to EGFR-TKIs in non-small cell lung cancer: restore after a drug holiday or switch to another EGFR-TKI?

The outcomes of first-generation EGFR-TKIs (Gefitnib and Erlotinib) have shown great advantages over traditional treatment strategies in patients with non-small cell lung cancer (NSCLC), but unfortunately we have to face the situation that most patients still fail to respond in the long term despite initially good control. Up to now, the mechanism of acquired resistance to EGFR-TKIs has not been fully clarified. Herein, we sought to compile the available clinical reports in the hope to better understanding the subsequent treatment choices, particularly on whether restoring after a drug holiday or switching to another EGFR-TKI is the better option after failure of one kind of EGFR-TKI.

Clinical management patterns and treatment outcomes in patients with non-small cell lung cancer (NSCLC) across Europe: EPICLIN-Lung study

BACKGROUND

Throughout Europe, physicians face similar challenges in non-small cell lung cancer (NSCLC) management, but comprehensive international information on usual clinical practice is lacking so the burden of NSCLC is not fully understood.

METHODS

This multinational, multicentre, non-interventional study (NCT00831909) was conducted in eight European countries. Patients with confirmed NSCLC were consecutively enrolled from January to March 2009 and followed for 12 months or until death. Information was collected on patient and disease characteristics, diagnosis and treatment patterns, and clinical outcomes. Spontaneously reported adverse events (AEs) were also recorded.

RESULTS

Data were available for 3508 patients. Most patients (77.5%) were male, median (range) age was 65.0 years (21.6-90.7), the majority of patients had a World Health Organization performance status of ≤1 (74.7%), and 10.8% were never smokers. The most prevalent histologies were adenocarcinoma (43.8%) and squamous-cell carcinoma (29.4%). Most patients presented with advanced disease (11.6% with stage IIIA, 18.7% with stage IIIB, 48.6% with stage IV). In stage IV disease, median progression-free survival and overall survival (months) by first-line treatment cluster were platinum regimens: 6.5, 10.8; non-platinum regimens: 4.3, 8.5; regimens with bevacizumab 8.7, 12.9; investigational regimens: 5.6, 10.8; best supportive care: 5.4, 6.6. The most frequently reported severe (Common Terminology Criteria for Adverse Events v3.0>2) AEs were blood/bone marrow (16.0%) and pulmonary/upper respiratory (7.8%). Key limitations of this study related to its non-interventional nature and wide regional focus; for example, achieving a representative sample of the overall NSCLC population, variation in recruitment between countries, and data based on information from medical records derived from routine visits.

CONCLUSIONS

The Epidemiological Study to Describe NSCLC Clinical Management Pattern in Europe-Lung (EPICLIN-Lung) study provides new insights into the descriptive patterns and clinical management strategies for NSCLC across Europe, and how they affect patient outcomes.

EGFR exon-level biomarkers of the response to bevacizumab/erlotinib in non-small cell lung cancer

Activating epidermal growth factor receptor (EGFR) mutations are recognized biomarkers for patients with metastatic non-small cell lung cancer (NSCLC) treated with EGFR tyrosine kinase inhibitors (TKIs). EGFR TKIs can also have activity against NSCLC without EGFR mutations, requiring the identification of additional relevant biomarkers. Previous studies on tumor EGFR protein levels and EGFR gene copy number revealed inconsistent results. The aim of the study was to identify novel biomarkers of the response to TKIs in NSCLC by investigating whole genome expression at the exon-level. We used exon arrays and clinical samples from a previous trial (SAKK19/05) to investigate the expression variations at the exon-level of 3 genes potentially playing a key role in modulating treatment response: EGFR, V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) and vascular endothelial growth factor (VEGFA). We identified the expression of EGFR exon 18 as a new predictive marker for patients with untreated metastatic NSCLC treated with bevacizumab and erlotinib in the first line setting. The overexpression of EGFR exon 18 in tumor was significantly associated with tumor shrinkage, independently of EGFR mutation status. A similar significant association could be found in blood samples. In conclusion, exonic EGFR expression particularly in exon 18 was found to be a relevant predictive biomarker for response to bevacizumab and erlotinib. Based on these results, we propose a new model of EGFR testing in tumor and blood.

Synergistic effect of afatinib with su11274 in non-small cell lung cancer cells resistant to gefitinib or erlotinib

Epidermal growth factor receptor (EGFR) and c-MET receptors are expressed on many non-small cell lung cancer (NSCLC) cells. Current single agent therapeutic targeting of a mutant EGFR has a high efficacy in the clinic, but is not curative. Here, we investigated the combination of targeting EGFR and c-MET pathways in NSCLC cells resistant to receptor tyrosine kinase inhibitors (TKIs), using RNA interference and inhibition by TKIs. Different NSCLC cell lines with various genomic characteristics (H358, H1650 and H1975) were transfected with EGFR-specific-siRNA, T790M-specific-siRNA, c-MET siRNA or the combination. Subsequently EGFR TKIs (gefitinib, erlotinib or afatinib) or monoclonal antibody cetuximab were combined respectively with the c-MET-specific TKI su11274 in NSCLC cell lines. The cell proliferation, viability, caspase-3/7 activity and apoptotic morphology were monitored by spectrophotometry, fluorimetry and fluorescence microscopy. The combined effect of EGFR TKIs, or cetuximab and su11274, was evaluated using a combination index. The results showed that the cell lines that were relatively resistant to EGFR TKIs, especially the H1975 cell line containing the resistance T790M mutation, were found to be more sensitive to EGFR-specific-siRNA. The combination of EGFR siRNA plus c-MET siRNA enhanced cell growth inhibition, apoptosis induction and inhibition of downstream signaling in EGFR TKI resistant H358, H1650 and H1975 cells, despite the absence of activity of the c-MET siRNA alone. EGFR TKIs or cetuximab plus su11274 were also consistently superior to either agent alone. The strongest biological effect was observed when afatinib, an irreversible pan-HER blocker was combined with su11274, which achieved a synergistic effect in the T790M mutant H1975 cells. In a conclusion, our findings offer preclinical proof of principle for combined inhibition as a promising treatment strategy for NSCLC, especially for patients in whom current EGFR-targeted treatments fail due to the presence of the T790M-EGFR-mutation or high c-MET expression.

Targeted therapy for lung cancer

Lung cancer is considered the number one killer among all cancers. Recent observations have altered the treatment paradigm for non-small-cell lung cancer (NSCLC). The discovery of activating mutations in the epidermal growth factor receptor and anaplastic lymphoma kinase positivity has made personalized treatment for NSCLC more feasible. Both erlotinib and crizotinib have been shown to be effective and safe for subgroup populations, and now personalized treatment for nonsquamous NSCLC has progressed even further. New tyrosine kinase inhibitors are being tested, resistant mutations are being studied, and new detection systems are being incorporated; all these developments will make the detection and treatment of the deadliest cancer more affordable, practical, and effective. The National Comprehensive Cancer Network has already incorporated these new developments into their guidelines for advanced nonsquamous NSCLC.

Analysis of driver mutations in female non-smoker Asian patients with pulmonary adenocarcinoma

Previous studies have revealed that EGFR mutation and/or EML4-ALK gene fusion rate was higher in the non-smoker Asian females with pulmonary adenocarcinoma. The aim of this study is to determine the distribution of known oncogenic driver mutations in the female non-smoker Asian patients with pulmonary adenocarcinoma. 104 consecutively resected lung adenocarcinomas from 396 non-smoker females (less than 100 cigarettes in a lifetime) at a single institution (Tongji University, Shanghai, China) were analyzed for mutations in EGFR, EML4-ALK, KRAS, HER2, BRAF, and PIK3CA. 73 (70.2 %) tumors harbored EGFR mutations; among these, 28 were deletions in exon 19, 44 were L858R missense changes, and eight were T790M mutations. 10 (9.6 %) harbored EML4-ALK fusions, two harbored KRAS mutations, two harbored BRAF mutations, and two harbored PI3K mutations. A majority of the mutations were mutually exclusive, except two with EGFR mutation and BRAF mutation, one with EML4-ALK fusions and PI3K mutation. Thus, 82.7 % (86 of 104; 95 % CI, 75.4-90.0 %) of lung adenocarcinomas from non-smoker females were found to harbor the well-known oncogenic mutations in five genes. Lung cancer in non-smoking Asian females is a distinct entity, with majority of this subgroup being developed by the oncogenic mutations. The prospective mutation examination in this population will be helpful for devising a targeted therapy for a majority of the patients.

The roles of epidermal growth factor receptor (EGFR) inhibitors in the management of lung cancer

Targeting epidermal growth factor receptor (EGFR) is an important treatment option for non-small cell lung cancer (NSCLC). These targeted therapies have been studied extensively in NSCLC in first line and subsequent lines, including maintenance in empiric fashion or in patients with tumors harboring the EGFR mutations. In this manuscript, we will review in details the evolutions of these targeted therapy in the management of NSCLC.

Phase I/II trial of a biweekly combination of S-1 plus docetaxel in patients with previously treated non-small cell lung cancer (KRSG-0601)

Background:

Combination of S-1, an oral fluorouracil derivative, plus docetaxel against non-small cell lung cancer (NSCLC) showed promising efficacy but clinically problematic emesis. A phase I/II study utilising a new schedule for this combination was conducted.

Methods:

A biweekly regimen of docetaxel on day 1 with oral S-1 on days 1–7 was administered to previously treated NSCLC patients. Doses of docetaxel/S-1 were escalated to 30/80, 35/80, and 40/80 mg m⁻², respectively, and its efficacy was investigated at the recommended dose below maximum tolerated dose (MTD).

Results:

In phase I study employing 13 patients, dose-limiting toxicities were febrile neutropenia and treatment delay, with the respective MTDs for docetaxel 40 mg m⁻²/S-1 80 mg m⁻². In the phase II study, 34 patients were treated with docetaxel 35 mg m⁻²/S-1 80 mg m⁻² for a median cycle of 6. The response and disease control rates were 34.3% (95% confidence interval (CI), 18.6–50.0%) and 62.9% (95% CI, 46.8–72.9%), respectively. Median progression-free survival was 150.5 days. Haematologic grade 4 toxicities were observed in neutropenia (11.8%) and thrombocytopenia (2.9%). Regarding non-haematologic toxicities, including emesis, there were no grade 3/4 side effects.

Conclusion:

Combination of 1-week administration of S-1 with biweekly docetaxel is safe and active for NSCLC.

Targeting the Met pathway in lung cancer

Dysregulation of Met signaling has been implicated in the initiation, progression and metastasis of human cancers, and therefore represents an attractive target for anticancer drug development. Met is overexpressed in non-small-cell lung cancer and its lack of staining in normal lung tissue makes it an attractive target. To date, erlotinib and gefitinib have established themselves as first-line therapy for non-small-cell lung cancer patients whose tumors harbor an EGF receptor gene mutation, and hence, it is crucial that we identify mechanisms of resistance that could be targeted by novel agents, while keeping an acceptable toxicity profile at the same time; something very important when we develop these new drugs. Inhibitors of the Met pathway represent a therapeutic alternative in this setting. In this review, we discuss the early clinical studies reported using two Met inhibitors, a monoclonal antibody (MetMAb) and a small molecule tyrosine kinase inhibitor (MGCD265).

Management of non-small cell lung cancer with oligometastasis

Patients with oligometastatic Non-Small Cell Lung Cancer (NSCLC) present a potential opportunity for curative therapy; however, the challenge remains the definitive treatment of their localized disease and ablation of their limited overt metastatic sites of disease. In selecting patients with oligometastatic NSCLC for definitive therapy, proper staging through radiographic studies, including PET and brain MRI, and the pathologic staging of the mediastinal lymph nodes and potential sites of metastatic disease, are critical. With that in mind, the available literature suggests that in highly selected patients with solitary metastases to the brain, adrenals and other organs, long term survival may be achieved with combined definitive therapy of both the primary lung tumor and the solitary metastatic site.

Routine EGFR and KRAS Mutation analysis using COLD-PCR in non-small cell lung cancer

Aims:  Epidermal growth factor receptor (EGFR) antagonists are particularly active in non-small cell lung cancer (NSCLC) patients with tumours bearing mutations in the EFGR gene. EGFR mutation prevalence is very low in squamous histology. Response rates using these drugs in patients with KRAS mutations are low, so available KRAS mutation information may aid treatment selection in the second-line setting. Since 2009, patients presenting to this hospital with non-squamous histology have been routinely screened for mutations in both the EGFR and KRAS genes, with results used to inform treatment. We present an analysis of 215 consecutive patients for whom EGFR mutation analysis was informative. Methodology:  EGFR and KRAS mutations were identified using a COLD-PCR technique confirmed with sequencing, which makes no prior assumption about location of specific mutations. Results were correlated with clinical and demographic data from hospital records, where available. Results:  The prevalence of patients with EGFR mutations was 14% and for KRAS mutations it was 27%. Despite the conventional understanding that EGFR and KRAS mutations are mutually exclusive, we identified two dual mutations. Of 29 patients identified with mutated EGFR, there were 3/8/8/10 mutations in exons 18/19/20/21 respectively. Exon 20 mutations were identified in a proportion exceeding many other series because of the unbiased mutation analysis used, and clinical benefit was seen in some of these. Of 23 different EGFR mutations identified, 11 have not previously been described in the literature. Conclusions:  The high prevalence of EGFR, KRAS or both mutations (40%) in this non-squamous population tested in clinical practice supports a policy of routine screening for these mutations in NSCLC.

Cancer treatment according to BRCA1 and BRCA2 mutations

Identification of germline mutations associated with significant cancer susceptibility has the potential to change all aspects of an individual's care, from screening to cancer treatment. For example, women with germline mutations in BRCA1 and BRCA2 have markedly elevated risks of breast and ovarian cancer and the identification of these germline mutations has led to specific screening and prevention strategies. More recently, advances in the understanding of the biological function of BRCA1 and BRCA2 have led to clinical trials testing targeted therapies in this population, particularly poly(ADP-ribose) polymerase (PARP) inhibitors. Unfortunately, the development of PARP inhibitors has not been as rapid as anticipated and has been more challenging than expected. Somatic mutations identified in many cancer types have allowed the development of therapeutics that target these mutated genes, and many of these agents obtained rapid regulatory approval and are currently in widespread clinical practice. Diagnostic testing has a central role in targeted cancer therapeutics for both somatic and germline mutations. Although the era of molecular medicine and targeted therapies has led to significant changes in the practice of oncology, new challenges continue to arise.

Pharmacogenetics and pharmacogenomics: role of mutational analysis in anti-cancer targeted therapy

The goal of cancer pharmacogenomics is to obtain benefit from personalized approaches of cancer treatment and prevention. Recent advances in genomic research have shed light on the crucial role of genetic variants, mainly involving genes encoding drug-metabolizing enzymes, drug transporters and targets, in driving different treatment responses among individuals, in terms of therapeutic efficacy and safety. Although a considerable amount of new targeted agents have been designed based on a finely understanding of molecular alterations in cancer, a wide gap between pharmacogenomic knowledge and clinical application still persists. This review focuses on the relevance of mutational analyses in predicting individual response to antitumor therapy, in order to improve the translational impact of genetic information on clinical practice.

Combining chemotherapy with epidermal growth factor receptor inhibition in advanced non-small cell lung cancer

Treatment of advanced stage lung cancer is changing rapidly. With the new found knowledge on molecular targets such as the epidermal growth factor receptor (EGFR), effective therapy is now available in a selected population with the target mutation. Single-agent epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) is a standard first-line therapy for patients with activating-EGFR mutation such as base-pair deletion in exon 19 or point mutation at exon 21. At the same time, this class of drugs may be combined with chemotherapy. Studies on the concurrent combination of chemotherapy and EGFR-TKI confirmed a lack of efficacy. A phase II study on sequential intercalated combination has demonstrated an improvement in progression-free survival (PFS), but this needs to be validated by the ongoing phase III study. The third approach is to combine EGFR-TKI as maintenance therapy after tumour response or stable disease to cytotoxic chemotherapy. Two phase III studies have shown improvement in PFS, but the use of biomarkers for the selection of maintenance therapy remains debatable. Cetuximab is a monoclonal antibody against EGFR and its combination with chemotherapy was shown to improve overall survival in an unselected population. A new biomarker using the H-score will help to select patients for this combination.

[Targeted agents in the treatment of lung cancer]

Lung cancer is in France, the leading cause of cancer death. Despite the dramatic advances that have allowed in a few years to go, for metastatic cancer, from a median survival without specific treatment of 4.5 months and now almost always more than one year, survival remains disappointing and further improvements are needed. Progress in the accumulated knowledge of the inner workings of normal and tumoral cells have paved the way for the development of targeted therapeutics called biological or simply targeted therapies. Two biological processes are already the target of marketed drugs, this is the way the receptor of epidermal growth factor (EGFR) and the path of neo-angiogenesis. It is almost assumed that, in the very near future, the inhibition of EML4-ALK will also be the subject of new drugs. In the medium term, it is conceivable that the molecular dissection of the tumors actually lead to the prescription of treatments tailored to mutations and other abnormalities that direct the growth of cancers.

[Protein tyrosine kinase inhibitors in cancer therapy]

The tyrosine kinase inhibitors (TKI) are small molecules of low molecular weight that inhibit tyrosine kinases, enzymes responsible for the activation of signal transduction cascades. Currently, a number of TKI received approval in various cancers, while others are in clinical development process: TKI are specifically clinically active when they target a tyrosine kinase (TK) with constitutional activity subsequent to a mutation, being then a master-gene driving transformation and tumour progression. Already, this drug-family provides a major therapeutic weapon against cancer.

The biology and clinical features of non-small cell lung cancers with EML4-ALK translocation

The anaplastic lymphoma kinase (ALK) acts as a dominant oncogenic driver following chromosomal rearrangements in certain cancers including non-small cell lung cancer (NSCLC). NSCLC with ALK translocation occurs in a specific subset of patients and results in unique clinical features. Crizotinib is a small molecule inhibitor of ALK kinase that has recently been approved by the FDA for the treatment of patients with ALK-positive NSCLC. Treatment with crizotinib results in clinical benefit rate of 85%-90% and a median progression-free survival of 9-10 months for this molecular subset of patients. Ongoing studies will define the impact of crizotinib on overall survival and provide insights into the resistance mechanisms and potential activation of alternate pathways. Heat shock protein 90 inhibitors also appear promising in the treatment of ALK-positive NSCLC patients, based on early results. This article reviews the characteristics, treatment, and ongoing research in patients with ALK-positive NSCLC.

Recent advances in lung cancer: summary of presentations from the 47 th annual meeting of the American Society of Clinical Oncology (ASCO) 2011

In the last several years, we have made slow but steady progress in developing new treatment strategies for patients with lung cancer. The use of molecularly targeted therapy has made a significant impact on the outcomes of patients with lung cancer. Further research is ongoing to identify more effective ways to target lung cancer. In the recently concluded 47 th annual meeting of the American Society of Clinical Oncology, there were several presentations on novel targeted therapies for lung cancer, in addition to the effective and optimal use of existing cytotoxic and targeted therapies for lung cancer. For this review, we have selected presentations that primarily have an impact on clinical practice, and some presentations regarding emerging therapeutic agents.

Erlotinib appears to produce prolonged remission of insulin-requiring type 2 diabetes associated with metabolic syndrome and chronic kidney disease

Patients with metabolic syndrome are at higher risk for type 2 diabetes and for chronic kidney disease. Metformin is the oral medication of choice for the treatment of type 2 diabetes in the absence of chronic kidney disease. There is a need for another oral glucose lowering agent for use in metabolic syndrome with type 2 diabetes and chronic kidney disease. We submit the first report of erlotinib, a once-daily oral medication for the treatment of non-small-cell lung cancer associated with specific genetic mutations, appearing to eliminate the need for insulin in insulin-requiring type 2 diabetes associated with metabolic syndrome and chronic kidney disease. The mechanism by which erlotinib, a tyrosine kinase inhibitor of the epidermal growth factor receptor may improve glycaemic control is unknown. Potential possibilities are explored.

Clinical outcomes in non-small cell lung cancers harboring different exon 19 deletions in EGFR

PURPOSE

Several deletions in exon 19 of epidermal growth factor receptor (EGFR) gene have been reported in non-small cell lung cancer (NSCLC). It is unknown if deletions occurring at different amino acid positions or of different sizes are associated with different clinical outcome to EGFR tyrosine kinase inhibitors (TKI).

EXPERIMENTAL DESIGN

This study enrolled NSCLC patients with deletions in EGFR exon 19. Patients who had received EGFR TKIs for advanced NSCLC were further evaluated for response rate (RR), progression-free survival (PFS), and overall survival (OS).

RESULTS

In 308 patients with deletions in EGFR exon 19, 298 had deletions encompassing the entire amino acid string from L747 through E749 (LRE deletions). EGFR TKIs were used in 204 patients with advanced NSCLC. Patients with non-LRE deletions had the least RR, compared with those with deletions from E746 or L747 (42.9%, 68.2%, and 79.6%, respectively; P = 0.022). Patients with non-LRE deletions had relatively short median PFS, though not significantly different from those with deletions from E746 or L747 (5.9, 9.8, and 10.5 months, respectively; P = 0.665). The OS was not different among patients with deletions occurring at different amino acid positions (P = 0.776). Deletions in exon 19 of different sizes were not associated with different RR, PFS, or OS.

CONCLUSIONS

Non-LRE deletions in exon 19 were associated with worse response to EGFR TKIs, compared with LRE deletions. Therefore, the expected clinical outcome under EGFR TKIs depends on not only the existence but also the types of deletions in exon 19.

Molecular therapeutic advances in personalized therapy of melanoma and non-small cell lung cancer

The incorporation of individualized molecular therapeutics into routine clinical practice for both non-small cell lung cancer (NSCLC) and melanoma are amongst the most significant advances of the last decades in medical oncology. In NSCLC activating somatic mutations in exons encoding the tyrosine kinase domain of the Epidermal Growth Factor Receptor (EGFR) gene have been found to be predictive of a response to treatment with tyrosine kinase inhibitors (TKI), erlotinib or gefitinib. More recently the EML4-ALK fusion gene which occurs in 3–5% of NSCLC has been found to predict sensitivity to crizotinib an inhibitor of the anaplastic lymphoma kinase (ALK) receptor tyrosine kinase. Similarly in melanoma, 50% of cases have BRAF mutations in exon 15 mostly V600E and these cases are sensitive to the BRAF inhibitors vemurafenib or dabrafenib. In a Phase III study of advanced melanoma cases with this mutation vemurafenib improved survival from 64% to 84% at 6 months, when compared with dacarbazine. In both NSCLC and melanoma clinical benefit is not obtained in patients without these genomic changes, and moreover in the case of vemurafenib the therapy may theoretically induce proliferation of cases of melanoma without BRAF mutations. An emerging clinical challenge is that of acquired resistance after initial responses to targeted therapeutics. Resistance to the TKI’s in NSCLC is most frequently due to acquisition of secondary mutations within the tyrosine kinase of the EGFR or alternatively activation of alternative tyrosine kinases such as C-MET. Mechanisms of drug resistance in melanoma to vemurafenib do not involve mutations in BRAF itself but are associated with a variety of molecular changes including RAF1 or COT gene over expression, activating mutations in RAS or increased activation of the receptor tyrosine kinase PDGFRβ. Importantly these data support introducing re-biopsy of tumors at progression to continue to personalize the choice of therapy throughout the patient’s disease course.

Mutation status of epidermal growth factor receptor and clinical features of patients with combined small cell lung cancer who received surgical treatment

The mutation status of epidermal growth factor receptor (EGFR) is correlated with the response of tumors to EGFR tyrosine kinase inhibitors in non-small cell lung cancer (NSCLC), suggesting its usefulness as a biomarker in NSCLC. The incidence of EGFR mutation in NSCLC is higher in China than in the United States and European countries. There have been some case reports concerning cases of gefitinib-responsive small cell lung cancer (SCLC) with EGFR mutations. However, few large studies concerning the mutation status of SCLC patients have been performed. We detected EGFR mutations in exons 19 and 21 of 40 SCLC patients, three of whom had combined SCLC, from the Zhejiang Cancer Hospital using xTAG technology. Only two patients with combined SCLC had an EGFR mutation in exon 19. To determine the EGFR mutation status and clinical features of combined SCLC, we retrospectively analyzed the clinical features of seven patients with combined SCLC who had undergone surgical treatment in Zhejiang Cancer Hospital between 2007 and 2010. EGFR mutations in exons 19 and 21 were detected using the pyrosequencing assay. Of the seven patients with combined SCLCs, 71.4% were male, 71.4% were heavy smokers, most were over 60 years old and 71.4% of the cases were combined adenocarcinoma. Chemotherapy treatment and tumor stage were correlated with survival time. Of the seven cases, one had a mutation in exon 19 of EGFR in both the conventional SCLC and SCLC combined adenocarcinoma components. Combined SCLC commonly occurs in patients who are heavy smokers, male and over 60 years old, and most of the combined type cases are adenocarcinoma. The treatment of combined SCLC may be applied to cases of conventional SCLC. EGFR mutations may therefore occur in combined SCLCs, especially in SCLC combined adenocarcinoma in China.

18F-FDG PET as a surrogate biomarker in non-small cell lung cancer treated with erlotinib: newly identified lesions are more informative than standardized uptake value

This study assesses the predictive value of (18)F-FDG PET for overall survival in lung cancer patients treated with a targeted drug.

METHODS

(18)F-FDG PET was performed in 125 second- or third-line non-small cell lung cancer (NSCLC) patients with a baseline Eastern Cooperative Oncology Group performance status less than 3 before treatment with erlotinib (150 mg daily) and 2 wk into treatment. The predictive value of (18)F-FDG PET, clinical parameters, and epithelial growth factor receptor (EGFR) mutation status for survival duration was evaluated by fitting accelerated failure time models.

RESULTS

New lesions on PET at 2 wk, EGFR mutation status, performance status, and baseline tumor burden were independent and significant predictors of overall survival. Reduction of maximum standardized uptake value by at least 35% was predictive of survival only when EGFR mutation status was not accounted for.

CONCLUSION

(18)F-FDG PET in second- or third-line NSCLC patients at 2 wk after starting treatment with erlotinib carries information about overall survival. Parametric survival modeling enables a quantitative assessment of the predictive value of (18)F-FDG PET in the context of clinical and laboratory information. New-lesion status by (18)F-FDG PET at 2 wk is a potential surrogate biomarker for survival in NSCLC.

First-SIGNAL: first-line single-agent iressa versus gemcitabine and cisplatin trial in never-smokers with adenocarcinoma of the lung

PURPOSE

Gefitinib has shown high response rate and improved progression-free survival (PFS) in never-smokers with lung adenocarcinoma (NSLAs). We compared efficacy of gefitinib with gemcitabine and cisplatin (GP) chemotherapy in this group of patients as first-line therapy.

PATIENTS AND METHODS

In this randomized phase III trial, a total of 313 Korean never-smokers with stage IIIB or IV lung adenocarcinoma, Eastern Cooperative Oncology Group performance status 0 to 2, and adequate organ function were randomly assigned to receive either gefitinib (250 mg daily) or GP chemotherapy (gemcitabine 1,250 mg/m(2) on days 1 and 8; cisplatin 80 mg/m(2) on day 1 every 3 weeks, for up to nine courses). The primary objective was to demonstrate better overall survival (OS) for gefitinib compared with GP in chemotherapy-naive NSLAs.

RESULTS

Three hundred nine patients were analyzed per protocol (gefitinib arm, n = 159; GP arm, n = 150). Gefitinib did not show better OS compared with GP (hazard ratio [HR], 0.932; 95% CI, 0.716 to 1.213; P = .604; median OS, 22.3 v 22.9 months, respectively). The 1-year PFS rates were 16.7% with gefitinib and 2.8% with GP (HR, 1.198; 95% CI, 0.944 to 1.520). Response rates were 55% with gefitinib and 46% with GP (P = .101). Myelosuppression, renal insufficiency, and fatigue were more common in the GP arm, but skin toxicities and liver dysfunction were more common in the gefitinib arm. Two patients (1.3%) in the gefitinib arm developed interstitial lung disease and died.

CONCLUSION

Gefitinib failed to demonstrate superior OS compared with GP as first-line therapy for NSLAs.

Clinical trials and biomarker research on lung cancer in China

INTRODUCTION

Over the past 10 years, there have been significant advances in clinical trials and translation research on lung cancer in China. These advances have changed the clinical practice of lung cancer treatment. Translation research has clarified many molecular mechanisms of lung cancer development, growth and metastasis. Based on these results, a few cancer-driving molecular targets were identified. Many new compounds that directly or indirectly target these driver genes have been developed and tested.

AREAS COVERED

Studies from the literature and ongoing work from the author's group were reviewed. This was with the aim of outlining the current state of a clinical trial cooperative group for lung cancer and highlighting some important clinical trials and biomarker research that have changed lung cancer clinical practice in China.

EXPERT OPINION

For biomarker-driven clinical research, it is important to identify subgroups of patients who are most likely to benefit from given targeted therapies. In this setting, the rapid identification and translation of validated biomarkers will be integral to the treatment of lung cancer. It is also important to utilize results from high-quality clinical research groups to enrich patients lives and to perform these challenging clinical trials.

Drug development to overcome resistance to EGFR inhibitors in lung and colorectal cancer

Epidermal growth factor receptor (EGFR) is a validated target in different human malignancies. EGFR tyrosine kinase inhibitors (TKIs) are known to contribute considerably to the extension of progression-free survival in EGFR-mutant non-small cell lung cancer and monoclonal antibodies (mAbs) targeting EGFR have also improved the efficacy outcomes in KRAS wild-type colorectal cancer. Nevertheless, a significant percentage of lung and colorectal cancer patients do not respond to anti-EGFR agents and secondary resistance after initial benefit is a challenging reality faced by clinicians. Extensive preclinical work on the potential mechanisms of resistance to EGFR inhibitors in different disease settings has guided the development of second-generation irreversible EGFR TKIs, more efficient anti-EGFR mAbs, and combination strategies with agents targeting other receptors and downstream effectors. In order to elucidate the role of the multiple therapeutic strategies under investigation to overcome EGFR inhibitors-resistance, rational drug development based on stringent preclinical data, biomarker validation and proper selection of patients in the ongoing clinical trials are of paramount importance. Preliminary results of clinical trials evaluating these approaches will be discussed in this manuscript, with emphasis on TKIs in lung cancer and mAbs in advanced colorectal cancer.

Epidermal growth factor receptor-tyrosine kinase inhibitor therapy is effective as first-line treatment of advanced non-small-cell lung cancer with mutated EGFR: A meta-analysis from six phase III randomized controlled trials

Gefiinib and erlotinib are two similar small molecules of selective and reversible epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs), which have been approved for second-line or third-line indication in previously treated advanced Non-small-cell lung cancer (NSCLC) patients. The results of comparing the EGFR-TKI with standard platinum-based doublet chemotherapy as the first-line treatment in advanced NSCLC patients with activated EGFR mutation were still controversial. A meta-analysis was performed to derive a more precise estimation of these regimens. Finally, six eligible trials involved 1,021 patients were identified. The patients receiving EGFR-TKI as front-line therapy had a significantly longer progression-free survival (PFS) than patients treated with chemotherapy [median PFS was 9.5 versus 5.9 months; hazard ratio (HR)=0.37; 95% confidence intervals (CI)=0.27-0.52; p<0.001]. The overall response rate (ORR) of EGFR-TKI was 66.60%, whereas the ORR of chemotherapy regimen was 30.62%, which was also a statistically significant favor for EGFR-TKI [relative risk (RR)=5.68; 95% CI=3.17-10.18; p<0.001]. The overall survival (OS) was numerically longer in the patients received EGFR-TKI than patients treated by chemotherapy, although the difference did not reach a statistical significance (median OS was 30.5 vs. 23.6 months; HR=0.94; 95% CI=0.77-1.15; p=0.57). Comparing with first-line chemotherapy, treatment of EGFR-TKI achieved a statistical significantly longer PFS, higher ORR and numerically longer OS in the advanced NSCLC patients harboring activated EGFR mutations, thus, it should be the first choice in the previously untreated NSCLC patients with activated EGFR mutation.

Second-generation irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs): a better mousetrap? A review of the clinical evidence

The discovery of activating epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) in 2004 heralded the era of molecular targeted therapy in NSCLC. First-generation small molecule, reversible tyrosine kinase inhibitors (TKIs) of EGFR, gefitinib and erlotinib, had been approved for second- or third-line treatment of NSCLC prior to the knowledge of these mutations. However, resistance to gefitinib and erlotinib invariably develops after prolonged clinical use. Two second-generation irreversible EGFR TKIs, afatinib (BIBW 2992) and dacomitinib (PF-00299804), that can potentially overcome the majority of these resistances are in late stage clinical development. Here I will review the clinical data of EGFR TKIs and discuss the appropriate future role of afatinib and dacomitinib in NSCLC: whether as replacement of erlotinib or gefitinib or only after erlotinib or gefitinib failure and whether different subgroups would benefit from different approaches.