IJC International Journal of Cancer

Transcription

1 IJC International Journal of Cancer Combination of chemotherapy and gefitinib as first-line treatment for patients with advanced lung adenocarcinoma and sensitive EGFR mutations: A randomized controlled trial Baohui Han 1, Bo Jin 1, Tianqing Chu 1, Yanjie Niu 1, Yu Dong 1, Jianlin Xu 1, Aiqing Gu 1, Hua Zhong 1, Huimin Wang 1, Xueyan Zhang 1, Chunlei Shi 1, Yanwei Zhang 1, Wei Zhang 1, Yuqing Lou 1, Lei Zhu 2 and Jun Pei 1 1 Department of Pulmonary, Shanghai Chest Hospital, Shanghai Jiaotong University, Shanghai, China 2 Department of Pathology, Shanghai Chest Hospital, Shanghai Jiaotong University, Shanghai, China To explore the optimal treatment strategy for patients who harbor sensitive EGFR mutations, a head-to-head study was performed to compare chemotherapy and gefitinib in combination or with either agent alone as first-line therapy, in terms of efficacy and safety. A total of 121 untreated patients with advanced lung adenocarcinoma who harbored sensitive EGFR mutations were randomly assigned to receive gefitinib combined with pemetrexed and carboplatin, pemetrexed plus carboplatin or gefitinib alone. The progression-free survival (PFS) of patients in the combination group (17.5 months, 95% CI, ) was longer than that of patients in the chemotherapy group (5.7 months, 95% CI, ) or gefitinib (11.9 months, 95% CI, ) group. The (hazard ratios) HRs of PFS for the combination group vs. chemotherapy and gefitinib groups were 0.16 (95% CI, , p < 0.001) and 0.48 (95% CI, , p ), respectively. The overall response rate (ORR) in the combination therapy group, chemotherapy group and the gefitinib group was 82.5%, 32.5% and 65.9%, respectively. The combinational strategy resulted in longer overall survival (OS) than chemotherapy (HR , p ) or gefitinib (HR , p ) alone. Our finding suggested that treatment with pemetrexed plus carboplatin combined with gefitinib could provide better survival benefits for patients with lung adenocarcinoma harboring sensitive EGFR mutations. Introduction Lung cancer is the leading cause of cancer-related death worldwide. 1,2 Due to the absence of symptoms in early stages, the lack of efficient lung cancer screening and misdiagnosis, most lung cancer cases are diagnosed in advanced stages, leading to only a minority of patients undergoing surgery. 3 Platinum-based chemotherapy has been found to provide a survival benefit for patients with advanced lung cancer. However, more than half of the patients cannot survive to 1 year, as most tumors quickly acquire resistance to chemotherapeutic drugs. 4,5 In the past decade, the recognition of a subgroup of patients with NSCLC harboring mutations of the EGFR that exhibit a favorable response to tyrosine kinase inhibitors (TKIs) has established EGFR TKIs as standard first-line Key words: chemotherapy, gefitinib, first-line, lung adenocarcinoma, sensitive EGFR mutations Additional Supporting Information may be found in the online version of this article. Grant sponsor: Key Projects of the Biomedicine Department, Science and Technology Commission of Shanghai Municipality; Grant number: DOI: /ijc History: Received 14 Jan 2017; Accepted 17 May 2017; Online 30 May 2017 Correspondence to: Baohui Han, Huaihai West Road No. 241, Shanghai, China, xkyyhan@gmail.com; Tel: therapy for patients with activating EGFR mutations However, most of those EGFR-mutant NSCLC patients develop acquired EGFR TKI resistance after months of first-line TKI treatment. Preclinical results demonstrated that the combination of chemotherapy and EGFR TKIs might have a synergistic effect on NSCLC cell growth in vitro. 13,14 Several reports manifested that EGFR TKIs such as erlotinib, and more recently osimertinib can have an important function as an ATP-binding cassette transporter inhibitors. 15 Examining the expression of ABCB1 (P-glycoprotein) and ABCG2 (breast cancer resistant protein, BCRP) could serve to predict the synergism of EGFR TKIs with chemotherapeutic agents by reversing multidrug resistance (MDR) Therefore, there is convincing evidence that EGFR TKIs can inhibit the MDR efflux of several chemotherapeutic agents. JMIT directly compared pemetrexed plus gefitinib to gefitinib alone for EGFR mutated NSCLC, the results demonstrated an improved progression-free survival (PFS) in pemetrexed plus gefitinib cohort. But they did not provide overall survival (OS) results. 20 Recently, the results in a single arm study from Japan showed that for untreated EGFR mutated NSCLC patients receiving combination of chemotherapy and EGFR TKI, the median PFS and OS were 18 months and 32 months, respectively. 21 However, they did not test whether the combinational strategy provide better survival benefits than single EGFR TKI agent, since the current standard of care for EGFR mutated lung adenocarcinoma patients were

2 1250 Combination of chemotherapy and gefitinib for lung adenocarcinoma What s new? Pairing platinum-based chemotherapy with the EGFR inhibitor gefitinib boosts survival time in lung cancer patients, new results show. Lung cancer remains one of the deadliest cancers worldwide, and though chemotherapy helps, the cancers quickly become resistant and many patients die within 1 year. In our study, the authors arranged a head-to-head comparison of gefitinib, chemotherapy and a combination of both in 121 patients. All patients had untreated advanced lung carcinoma with EGFR mutation. Patients receiving gefitinib combined with chemotherapy averaged 18 months progression-free survival (PFS), compared to 6 months for chemotherapy alone and 12 months with only gefitinib. EGFR TKI alone, followed by chemotherapy under progression (second line and beyond). At the time of study design of our study, the guideline in china suggested first-line TKI therapy or first-line chemotherapy followed by second-line TKI therapy for sensitive EGFR mutated lung adenocarcinoma. So, we designed our study to directly compare different strategy (chemotherapy and gefitinib in combination, chemotherapy or gefitinib) in terms of efficacy and safety as first-line therapy in this population. Patients and Methods Study design and patients Our study was a three-arm randomized open-label phase II study comparing pemetrexed plus carboplatin and gefitinib to either pemetrexed plus carboplatin or gefitinib alone as first-line therapy for lung adenocarcinoma patients harboring sensitive EGFR mutations. The study was approved by the Institutional Review Board of the Shanghai Chest Hospital and was conducted in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines. All patients provided written informed consent before any study-related procedure. Patients were eligible for our study if they were 18 years of age or older, had a histologic or cytologic diagnosis of locally advanced or metastatic adenocarcinoma (Stage IIIB or IV) with a confirmed activating mutation of EGFR (an exon 19 deletion or an exon 21 L858R point mutation). The staging was performed according to the 7th edition of the TNM classification. The highly sensitive method termed Amplification Refractory Mutation System (ARMS) was used to detect mutations in the EGFR gene according to the manufacturer s protocol of the DxS EGFR mutation test kit (DxS). 22 Patients required at least one measurable lesion meeting Response Evaluation Criteria in Solid Tumors (RECIST) guidelines and an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 1. Patients were excluded from the study if they had received systemic anticancer therapy for advanced disease; had symptomatic or untreated brain metastases or had unstable systemic disease, including active infection, uncontrolled hypertension, unstable angina or c registered with ClinicalTrials.gov, number NCT Randomization Patients were allocated in a 1:1:1 ratio using minimization software. Randomization was stratified by EGFR mutation status. Throughout the study, clinicians and study participants were not masked to the identity of the study treatment. Treatment protocol Patients with advanced lung adenocarcinoma who harbored sensitive EGFR mutations were randomly assigned to three groups. The combination therapy group received pemetrexed (500 mg/m(2) on Day 1) plus carboplatin (AUC 5 on Day 1) combined with gefitinib (250 mg/day on Days 5 21) and repeated every four weeks for up to six cycles and then continued to receive pemetrexed combined with gefitinib every four weeks. The chemotherapy group received the same chemotherapy regimen as the combination group every four weeks for up to six cycles and then continued to receive pemetrexed alone every four weeks. The gefitinib group received gefitinib alone. All therapies were continued until progression, unacceptable toxicity or death. Tumor response was assessed by use of CT with RECIST every 4 weeks until treatment cessation or disease progression. Outcomes measure The primary end point was PFS. Secondary end points included OS, overall response rate (ORR) and the adverseevent profile. PFS was defined as the time from the date of randomization to the first date of disease progression or death from any cause. For patients not known to have died as of the data cut-off date and who did not have objective progressive disease, PFS was censored at the date of the last objective progression-free disease assessment. OS was measured from the date of randomization to the date of death. For each patient who was not known to have died as of the data inclusion cut-off date for a particular analysis, OS was censored for that analysis at the date of last prior contact. Toxicity was graded according to National Cancer Institute Common Terminology Criteria for adverse events, version 40. Analyses were performed on an intention-to-treat (ITT) basis. Statistical analysis The leading parameter for sample size calculation was PFS. The sample size was set at 120 patients in total using a logrank-test power analysis, on the basis of several assumptions: a median PFS of 18 months with chemotherapy combined with EGFR TKI, 9 months for EGFR TKI alone, 6 months for chemotherapy on the basis of data from results shown in

3 Han et al Table 1. Patient demographics and baseline disease characteristics No. of patients (%) Characteristic AC 1 G(N540) AC (N 5 40) G (N 5 41) p Age, years <65 27 (57.5) 31 (72.5) 27 (43.9) (42.5) 9 (27.5) 14 (56.1) Gender Male 15 (37.5) 17 (42.5) 18 (43.9) Female 25 (62.5) 23 (57.5) 23 (56.1) Smoking status Smoker 13 (32.5) 11 (27.5) 14 (34.1) Never smoker 27 (67.5) 29 (72.5) 27 (65.9) ECOG PS 0 8 (20.0) 10 (25.0) 9 (22.0) (80.0) 30 (75.0) 32 (78.0) EGFR mutation type 19del 21 (52.5) 20 (50.0) 21 (51.2) L858R 19 (47.5) 20 (50.0) 20 (47.8) Stage IIIB 8 (20.0) 7 (17.5) 5 (12.2) IV 32 (80.0) 33 (82.5) 36 (87.8) Second-line therapy No [first-line going on] 14 (35.0) [6 (15.0)] 2 (5.0) [2 (5.0)] 10 (24.4) [1 (2.4)] Yes 26 (65.0) 38 (95.0) 31 (75.6) Target therapy 0 (0.0) 35 (87.5) 3 (7.3) Chemotherapy 26 (65.0) 3 (7.5) 28 (68.3) Cycle of first-line chemotherapy 6 30 (75.0) 17 (42.5) <6 10 (25.0) 23 (57.5) Abbreviations: A, pemetrexed; C, carboplatin; G, gefitinib. Comparisons of categorical variables were performed using v 2 test. previous reports; 7,21 and 80% power to detect a hazard ratio (HR) of 0.50 with an overall a level of 5%. Clinical parameters and adverse events among three arms were analyzed using the v 2 test. Survival results were summarized as median values and two-sided 95% confidence intervals (CIs) and were analyzed using Kaplan Meier s technique, whereas the log-rank test was used for comparisons among subgroups. Multivariable adjusted hazard ratios (HRs) for allcause mortality by patient and treatment pattern were estimated using Cox regression. HRs were calculated along with their corresponding 95% CIs as measurements of association. SPSS software, version 22 (SPSS, Inc., Chicago, IL), was used for all statistical analyses. Results Between April 3, 2011 and December 2, 2015, 121 patients were randomly assigned to receive chemotherapy plus gefitinib (N 5 40), chemotherapy (N 5 40) or gefitinib (N 5 41). The demographics were balanced between the treatment arms (Table 1). At the time of analysis of our study, 34, 38 and 40 patients discontinued the first-line combination, chemotherapy and gefitinib groups, respectively, due to disease progression, protocol violation (Fig. 1); 20, 27 and 29 patients in combination and chemotherapy, and gefitinib groups have OS events. Efficacy The PFS for patients in the combination, chemotherapy and gefitinib groups was 17.5 (95% CI, ), 11.9 (95% CI, ) and 5.7 months (95% CI, ), respectively. The HRs of PFS for the combination group vs. chemotherapy and gefitinib groups were 0.16 (95% CI, , p < 0.001) and 0.48 (95% CI, , p ), respectively (Fig. 2). The HR of PFS for the gefitinib group vs. chemotherapy group was 0.35 (95% CI, , p < 0.001). Subgroup analyses showed a statistically significant improvement in PFS in the combination arm vs. the gefitinib arm in the following

4 1252 Combination of chemotherapy and gefitinib for lung adenocarcinoma Figure 1. Flow diagram of patients studied alone (Supplementary Fig. S1). In multivariate analysis, EGFR mutation status and ECOG scores were prognostic factors for PFS (Supplementary Table S1). ORR was 82.5% in the combination therapy group, 32.5% in the chemotherapy group and 65.9% in the gefitinib group. Figure 3 shows the best percent change from baseline in terms of size of target lesion for patients with measurable disease. The OS for patients in the combination, chemotherapy and gefitinib groups were 32.6 (95% CI, ), 24.3 (95% CI, ) and 25.8 months (95% CI, ), respectively. The HRs of OS for the combination group vs. chemotherapy and gefitinib groups were 0.46 (95% CI, , p ) and 0.36 (95% CI, , p ), respectively (Fig. 4). The HR of OS for the gefitinib group vs. chemotherapy group was 1.03 (95% CI, , p ). Figure 2. Kaplan Meier plots of PFS comparing patients receiving different treatment strategies. [Color figure can be viewed at wileyonlinelibrary.com] subgroup: age <65, female, never smoker, PS 5 1, stage IV and patients with exon 21 L858R point mutation. All of the clinical subgroups derived better PFS benefits from combination of chemotherapy and gefitinib therapy compared to chemotherapy Safety The most common grade 3 4 adverse events were neutropenia (4 patients [10.0%] in the combinational group, 5 patients [12.5%] in the chemotherapy group and 0 patient [0.0%] in the gefitinib group); fatigue (3 patients [7.5%] in the combinational group, 2 patients [5.0%] in the chemotherapy group and 0 patient [0.0%] in the gefitinib group); liver dysfunction (4 patients [10.0%] in the combinational group, 0 patient

5 Han et al Figure 3. Waterfall plot of the best percent change in target lesions from baseline for 121 patients based on investigator assessment. [Color figure can be viewed at wileyonlinelibrary.com] Figure 4. Kaplan Meier plots of OS comparing patients receiving different treatment strategies. [Color figure can be viewed at wileyonlinelibrary.com] [0.0%] in the chemotherapy group and 1 patient [2.5%] in the gefitinib group) and skin allergy (4 patients [10.0%] in the combinational group, 4 patients [10.0%] in the chemotherapy group and 0 patient [0.0%] in the gefitinib group). There were no grade 5 adverse events (Table 2). Discussion Our study examined the efficacy and safety of gefitinib combined with carboplatin and pemetrexed for first-line treatment of advanced NSCLC with sensitive EGFR mutations. The study met its primary end point (PFS) at the last day of follow-up (October 1, 2016). The PFS results for the three treatment arms are clearly divided by the performed test. The PFS of the combination group was significantly longer than those in the gefitinib and chemotherapy groups. It is stated for the first time that gefitinib plus chemotherapy improves median survival compared to gefitinib alone. The median OS for the combination was 32.6 months, which is similar to that reported in the FASTACT-2 study, intercalating chemotherapy with erlotinib. 23 Somatic mutations of EGFR have been associated with sensitivity to EGFR-TKIs in patients with advanced NSCLC. However, most of those EGFR mutated NSCLC patients develop acquired EGFR TKI resistance after months of first-line TKI treatment. It was reported that simultaneous treatment with gefitinib and pemetrexed prevented the appearance of gefitinib resistance mediated by the T790M mutation or epithelial-to-mesenchymal transition (EMT) in PC9 and HCC827 cells, respectively. 24 Sequential use of chemotherapy followed by gefitinib enhances the antitumor effect in NSCLC cell lines poorly responsive to reversible EGFR TKIs. 25 In the past decade, several clinical trials have evaluated the efficacy of EGFR TKIs combined with chemotherapy by directly comparing EGFR TKI plus chemotherapy to chemotherapy alone However, in contrast with the results in the present trial, most of those studies failed to present superior survival benefits from the combination strategy compared to those from

6 1254 Combination of chemotherapy and gefitinib for lung adenocarcinoma Table 2. Treatment-related adverse events AC 1 G(N540) AC (N 5 40) G (N 5 41) p All (%) Grade 3 4 (%) All (%) Grade 3 4 (%) All (%) Grade 3 4 (%) Grade 3 4 Liver dysfunction 21 (52.5) 4 (10.0) 11 (27.5) 0 (0.0) 15 (36.6) 1 (2.4) Neutropenia 17 (42.5) 4 (10.0) 14 (35.0) 5 (12.5) 3 (7.3) 0 (0.0) Astriction 19 (47.5) 0 (0.0) 23 (57.5) 0 (0.0) 5 (12.2) 0 (0.0) 1.0 Fatigue 9 (22.5) 3 (7.5) 11 (27.5) 2 (5.0) 7 (17.1) 0 (0.0) Anemia 17 (42.5) 0 (0.0) 16 (40.0) 0 (0.0) 11 (26.8) 0 (0.0) 1.0 Nausea 20 (50.0) 0 (0.0) 16 (40.0) 0 (0.0) 6 (14.6) 0 (0.0) 1.0 Diarrhea 19 (46.3) 0 (0.0) 8 (20.0) 0 (0.0) 17 (41.5) 0 (0.0) 1.0 Skin rash 24 (60.0) 4 (10.0) 3 (7.5) 0 (0.0) 22 (53.7) 4 (9.8) Anorexia 16 (40.0) 0 (0.0) 16 (40.0) 0 (0.0) 8 (19.5) 0 (0.0) 1.0 Thrombocytopenia 10 (25.0) 0 (0.0) 10 (25.0) 0 (0.0) 2 (4.9) 0 (0.0) 1.0 Leucopenia 8 (20.0) 0 (0.0) 10 (25.0) 0 (0.0) 3 (7.3) 0 (0.0) 1.0 Abbreviations: A, pemetrexed; C, carboplatin; G, gefitinib. Comparisons of grade 3 4 adverse events among three arms were performed using v 2 test. None of the p-value is small than chemotherapy alone. 26,27,32,33 There are several factors that can explain these failures. The most important reasons are that the patients included in the earlier studies were Caucasian and that EGFR mutations were unselected. 34 EGFR TKIs cannot provide benefits for EGFR wild type patients, and only approximately 15% of Caucasians carry EGFR mutations. Three subsequent Asian studies demonstrated that the combination of chemotherapy and EGFR TKI improved survival compared to chemotherapy alone. 23,30,31 Among those three studies, subgroup analysis of FASTACT2 showed that for the EGFR-mutated population, the combination strategy (erlotinib plus gemcitabine and platinum) could provide superior PFS (HR ) and OS (HR ) to that of chemotherapy alone. In our study, first-line gefitinib therapy could provide a significantly longer PFS than first-line chemotherapy in EGFR mutated lung adenocarcinoma. Similar results were reported in several trials. 7,11 For this population, the current standard therapy is EGFR TKI alone, followed by chemotherapy under progression (second line and beyond). In this setting, the most important question is whether the combination strategy is better than EGFR TKI alone. The results of our study indicate that gefitinib combined with carboplatin and pemetrexed as first-line therapy provides better survival benefits than gefitinib alone. Similar results were also achieved in a previous study in which gefitinib plus pemetrexed provided greater PFS than gefitinib alone (15.8 months vs months, HR ) as first-line therapy for EGFR-mutated NSCLC. 20 The results in another prospective single arm clinical trial achieved a median PFS of 18.0 months for EGFR-mutated patients using pemetrexed plus gefitinib. 21 According to a previous study, the combination of EGFR TKIs and cisplatin is also an effective treatment against EGFR TKI-resistant cancer. 35 Similarly, in our unpublished study, we used to evaluate the anti-tumor effect of additional pemetrexed or carboplatin to gefitinib in vitro (PC-9), and the results demonstrated that these drugs have a synergistic effect (Supplementary Fig. S2). In addition, FASTACT2 used to evaluate erlotinib plus gemcitabine and platinum therapy in NSCLC patients showed that the combination of platinum-based chemotherapy and TKI exhibited favorable tolerability and promising efficacy. 23 In our study, we added carboplatin to pemetrexed as a chemotherapeutic agent. To avoid high incidences of adverse events, gefitinib was administered from Day 5 to Day 21. The median PFS for the combination group in the current trial was 17.5 months. Another single arm study that added additional cisplatin and docetaxel to gefitinib as first-line treatment in patients harboring an EGFR activating mutation achieved a median PFS of 19.2 months. 36 Previously, a multicenter study compared the efficacy of the combination of pemetrexed and erlotinib with either agent alone as second-line treatment in never-smokers with non-squamous NSCLC. Subgroup analysis showed that among the 24 EGFR mutated patients, the combination strategy improved OS compared to erlotinib or pemetrexed alone. 30 However, the PFS was not significantly different between the combination group and single erlotinib therapy group. Similarly, Hirsch et al. comparederlotinib alone to erlotinib with paclitaxel and carboplatin as first-line therapy for advanced NSCLC. Subgroup analysis showed that six patients with acting EGFR mutations did not have an improved 6-month PFS rate or PFS from the combination therapy compared to the nine patients who received erlotinib alone. 37 The failure to demonstrate superior efficacy for the combination strategy in the EGFR mutated subgroup in those two studies could be explained by the small sample sizes. In our study, 65.0% patients in the combination arm, 95.0% patients in the chemotherapy arm, 75.6% patients in gefitinib arm received second-line therapies. So, we deemed that the OS advantage in combination arm was attributable to a treatment effect of firstline therapy but not to post-study treatments.

7 Han et al In our study, to avoid hematological and gastrointestinal toxicities, pemetrexed and carboplatin were administered every 4 weeks and gefitinib was administered on Days The median PFS of 17.5 months was similar to that noted previously with 3 weekly pemetrexed, and gefitinib on Days This intercalated combination strategy caused a minimal increase in toxicities compared to chemotherapy or gefitinib alone. The common grade 3 4 treatment-related adverse events in combination arm were liver dysfunction, neutropenia, fatigue and skin rash. The incidences of grade 3 4 treatment-related neutropenia were similar between the combination (10.0%) and chemotherapy arms (12.5%). None of the patients in gefitinib arm had grade 3 4 neutropenia, suggesting neutropenia is more likely associated with chemotherapy use. Combinational strategy resulted a modest increase in liver dysfunction than gefitinib arm, which is consistent with the results in JMIT study. In conclusion, our study demonstrated that pemetrexed plus carboplatin combined with gefitinib provided longer PFS, OS compared with either agent alone in patients with sensitive EGFR-mutant lung adenocarcinoma. The toxicity profiles show good tolerance by patients. This combinational strategy may yield new choices for the treatment of sensitive EGFRmutant NSCLC. This trial was a monocenter study, and the results should be interpreted considering this limitation. These results need to be confirmed through a multicenter study. Disclosure Baohui Han has consulted for AstraZeneca, Roche Pharmaceutical Company. He also received payment for speaking from AstraZeneca Pharmaceutical Company and Lily Pharmaceutical Company. All remaining authors have declared no conflicts of interest. Acknowledgements The authors would like to acknowledge support from the Department of Pathology of Shanghai Chest Hospital. We also thank the patients and their families for their contributions to our study. References 1. Torre LA, Bray F, Siegel RL, et al. Global cancer statistics, CA Cancer J Clin 2015;65: Chen W, Zheng R, Zeng H, et al. Annual report on status of cancer in China, Chin J Cancer Res 2015;27: Seigneurin A, Field JK, Gachet A, et al. A systematic review of the characteristics associated with recall rates, detection rates and positive predictive values of computed tomography screening for lung cancer. Ann Oncol 2014;25: Zhang W, Lei P, Dong X, et al. The new concepts on overcoming drug resistance in lung cancer. Drug Des Dev Ther 2014;8: Hellmann MD, Li BT, Chaft JE, et al. Chemotherapy remains an essential element of personalized care for persons with lung cancers. Ann Oncol 2016;27: Lynch TJ, Bell DW, Sordella R, et al. Activating mutations in the epidermal growth factor receptor underlying responsiveness of non-small cell lung cancer to gefitinib. N Engl J Med 2014;350: Mok TS, Wu YL, Thongprasert S, et al. Gefitinib or carboplatin-paclitaxel in pulmonary adenocarcinoma. N Engl J Med 2009;361: Maemondo M, Inoue A, Kobayashi K, et al. Gefitinib or chemotherapy for non-small-cell lung cancer with mutated EGFR. N Engl J Med 2010; 362: Mitsudomi T, Morita S, Yatabe Y, et al. Gefitinib versus cisplatin plus docetaxel in patients with non-small-cell lung cancer harbouring mutations of the epidermal growth factor receptor (WJTOG 3405): an open label, randomised phase 3 trial. Lancet Oncol 2010;11: Gao G, Ren S, Li A, et al. Epidermal growth factor receptor-tyrosine kinase inhibitor therapy is effective as first-line treatment of advanced nonsmall-cell lung cancer with mutated EGFR: a meta-analysis from six phase III randomized controlled trials. Int J Cancer 2012;131: Rosell R, Carcereny E, Gervais R, et al. Erlotinib versus standard chemotherapy as first-line treatment for European patients with advanced EGFR mutation-positive non-small-cell lung cancer (EURTAC): a multicentre, open-label, randomised phase 3 trial. Lancet Oncol 2012;13: Kim ES, Hirsh V, Mok T, et al. Gefitinib versus docetaxel in previously treated non-small cell lung cancer (INTEREST): a randomised phase iii trial. Lancet 2008;372: Okabe T, Okamoto I, Tsukioka S, et al. Synergistic antitumor effect of S-1 and the epidermal growth factor receptor inhibitor gefitinib in nonsmall cell lung cancer cell lines: role of gefitinibinduced down-regulation of thymidylate synthase. Mol Cancer Ther 2008;7: Chen CY, Chang YL, Shih JY, et al. Thymidylate synthase and dihydrofolate reductase expression in non-small cell lung carcinoma: the association with treatment efficacy of pemetrexed. Lung Cancer 2011;74: Hsiao SH, Lu YJ, Li YQ, et al. Osimertinib (AZD9291) attenuates the function of multidrug resistance-linked ATP-binding cassette transporter ABCB1 in vitro. Mol Pharm 2016;13: Mi YJ, Liang YJ, Huang HB, et al. Apatinib (YN968D1) reverses multidrug resistance by inhibiting the efflux function of multiple ATPbinding cassette transporters. Cancer Res 2010;70: Dai CL, Tiwari AK, Wu CP, et al. Lapatinib (Tykerb, GW572016) reverses multidrug resistance in cancer cells by inhibiting the activity of ATP-binding cassette subfamily B member 1 and G member 2. Cancer Res 2008;68: Yang CH, Huang CJ, Yang CS, et al. Gefitinib reverses chemotherapy resistance in gefitinibinsensitive multidrug resistant cancer cells expressing ATP-binding cassette family protein. Cancer Res 2005;65: Cortes-Dericks L, Carboni GL, Schmid RA, et al. Putative cancer stem cells in malignant pleural mesothelioma show resistance to cisplatin and pemetrexed. Int J Oncol 2010;37: Cheng Y, Murakami H, Yang PC, et al. Randomized phase II trial of gefitinib with and without pemetrexed as first-line therapy in patients with advanced nonsquamous non-small-cell lung cancer with activating epidermal growth factor receptor mutations. J Clin Oncol 2016;34: Yoshimura N, Kudoh S, Mitsuoka S, et al. Phase II study of a combination regimen of gefitinib and pemetrexed as first-line treatment in patients with advanced non-small cell lung cancer harboring a sensitive EGFR mutation. Lung Cancer 2015;90: Zhang Q, Zhu L, Zhang J. Epidermal growth factor receptor gene mutation status in pure squamous-cell lung cancer in Chinese patients. BMC Cancer 2015;15: Wu YL, Lee JS, Thongprasert S, et al. Intercalated combination of chemotherapy and erlotinib for patients with advanced stage non-small-cell lung cancer (FASTACT-2): a randomised, doubleblind trial. Lancet Oncol 2013;14: La Monica S, Madeddu D, Tiseo M, et al. Combination of gefitinib and pemetrexed prevents the acquisition of TKI resistance in NSCLC cell lines carrying EGFR-activating mutation. J Thorac Oncol 2016;11: Dal Bello MG, Alama A, Barletta G, et al. Sequential use of vinorelbine followed by gefitinib enhances the antitumor effect in NSCLC cell lines poorly responsive to reversible EGFR tyrosine kinase inhibitors. Int J Cancer 2015; 137: Michael M, White SC, Abdi E, et al. Multicenter randomized, open-label phase II trial of sequential erlotinib and gemcitabine compared with gemcitabine monotherapy as first-line therapy in elderly or ECOG PS two patients with advanced NSCLC. Asia Pac J Clin Oncol 2015;11: Dittrich C, Papai-Szekely Z, Vinolas N, et al. A randomised phase II study of pemetrexed versus pemetrexed1erlotinib as second-line treatment for locally advanced or metastatic non-squamous non-small cell lung cancer. Eur J Cancer 2014;50: Auliac JB, Chouaid C, Greiller L, et al. Randomized open-label non-comparative multicenter

8 1256 Combination of chemotherapy and gefitinib for lung adenocarcinoma phase II trial of sequential erlotinib and docetaxel versus docetaxel alone in patients with nonsmall-cell lung cancer after failure of first-line chemotherapy: GFPC study. Lung Cancer 2014;85: Stinchcombe TE, Roder J, Peterman AH, et al. A retrospective analysis of VeriStrat status on outcome of a randomized phase II trial of first-line therapy with gemcitabine, erlotinib, or the combination in elderly patients (age 70 years or older) with stage IIIB/IV non-small-cell lung cancer. J Thorac Oncol 2013;8: Lee DH, Lee JS, Kim SW, et al. Three-arm randomised controlled phase 2 study comparing pemetrexed and erlotinib to either pemetrexed or erlotinib alone as second-line treatment for never-smokers with nonsquamous non-small cell lung cancer. Eur J Cancer 2013;49: Mok TS, Wu YL, Yu CJ, et al. Randomized, placebo-controlled, phase II study of sequential erlotinib and chemotherapy as first-line treatment for advanced non-small-cell lung cancer. J Clin Oncol 2009;27: Gatzemeier U, Pluzanska A, Szczesna A, et al. Phase III study of erlotinib in combination with cisplatin and gemcitabine in advanced nonsmall-cell lung cancer: the Tarceva Lung Cancer Investigation Trial. JClinOncol2007;25: Herbst RS, Prager D, Hermann R, et al. TRIB- UTE: a phase III trial of erlotinib hydrochloride (OSI-774) combined with carboplatin and paclitaxel chemotherapy in advanced non-small-cell lung cancer. J Clin Oncol 2005;23: Ahn MJ, Lee J, Park YH, et al. Korean ethnicity as compared with white ethnicity is an independent favorable prognostic factor for overall survival in non-small cell lung cancer before and after the oral epidermal growth factor receptor tyrosine kinase inhibitor era. J Thorac Oncol 2010;5: Lee JG, Wu R. Combination erlotinib-cisplatin and Atg3-mediated autophagy in erlotinib resistant lung cancer. PLoS One 2012;7:e Shintaro K, Yuichiro O, Hidehito H, et al. Phase II study of gefitinib and inserted cisplatin plus docetaxel as a first-line treatment for advanced non-small cell lung cancer harboring an epidermal growth factor receptor activating mutation. J Clin Oncol 2013;31:abstr Hirsch FR, Kabbinavar F, Eisen T, et al. A randomized, phase II, biomarker-selected study comparing erlotinib to erlotinib intercalated with chemotherapy in first-line therapy for advanced non-small-cell lung cancer. J Clin Oncol 2011;10: