Epidermal growth factor receptor mutation analysis in cytological specimens and responsiveness to gefitinib in advanced non-small cell lung cancer patients

Background： Epidermal growth factor receptor（EGFR） mutation is the key predictor of EGFR tyrosine kinase inhibitors（TKIs） efficacy in non-small cell lung cancer（NSCLC）. We conducted this study to verify the feasibility of EGFR mutation analysis in cytological specimens and investigate the responsiveness to gefitinib treatment in patients carrying EGFR mutations.Methods： A total of 210 cytological specimens were collected for EGFR mutation detection by both direct sequencing and amplification refractory mutation system（ARMS）. We analyzed EGFR mutation status by both methods and evaluated the responsiveness to gefitinib treatment in patients harboring EGFR mutations by overall response rate（ORR）, disease control rate（DCR） and progression free survival（PFS）.Results： Of all patients, EGFR mutation rate was 28.6%（60/210） by direct sequencing and 45.2%（95/210） by ARMS（P〈0.001） respectively. Among the EGFR wild type patients tested by direct sequencing, 26.7% of them were positive by ARMS. For the 72 EGFR mutation positive patients treated with gefitinib, the ORR, DCR and median PFS were 69.4%, 90.2% and 9.3 months respectively. The patients whose EGFR mutation status was negative by direct sequencing but positive by ARMS had lower ORR（48.0% vs. 80.9%, P=0.004） and shorter median PFS（7.4 vs. 10.5 months, P=0.009） as compared with that of EGFR mutation positive patients by both detection methods. Conclusions： Our study verified the feasibility of EGFR analysis in cytological specimens in advanced NSCLC. ARMS is more sensitive than direct sequencing in EGFR mutation detection. EGFR Mutation status tested on cytological samples is applicable for predicting the response to gefitinib. Abundance of EGFR mutations might have an influence on TKIs efficacy.

Relationship between epidermal growth factor receptor gene mutation and copy number in Chinese patients with non-small cell lung cancer

Epidermal growth factor receptor(EGFR) gene mutation and copy number are useful predictive markers that guide the selection of non-small cell lung cancer(NSCLC) patients for EGFR-targeting therapy.This study aimed to investigate the correlation between EGFR gene mutation and copy number and clinicopathologic characteristics of Chinese patients with NSCLC.NSCLC specimens collected from 205 patients between November 2009 and January 2011 were selected to detect EGFR gene mutations with real-time polymerase chain reaction(RT-PCR) and to detect EGFR gene copy number with fluorescence in situ hybridization(FISH).EGFR mutations primarily occurred in females,non-smokers,and patients with adenocarinomas(all P < 0.001).Tissues from 128(62%) patients were FISH-positive for EGFR,including 37(18%) with gene amplification and 91(44%) with high polysomy.EGFR gene mutation was correlated with FISH-positive status(R = 0.340,P < 0.001).Multivariate analysis showed that not smoking(OR = 5.910,95% CI = 2.363-14.779,P < 0.001) and having adenocarcinoma(OR = 0.122,95% CI = 0.026-0.581,P = 0.008) were favorable factors for EGFR gene mutation.These results show a high frequency of EGFR FISH positivity in NSCLC tissues from Chinese patients and a significant relevance between EGFR gene mutations and FISH-positive status.Among the FISH-positive samples,EGFR gene mutation occurred more frequently in samples with gene amplification compared to those with high polysomy,suggesting that EGFR mutation and gene amplification should be used as clinical decision parameters to predict response to EGFR-targeting therapy.

Dramatic response to immunotherapy in an epidermal growth factor receptor-mutant non-small cell lung cancer: A case report

BACKGROUND The advent of immune checkpoint inhibitors(ICIs)has revolutionized the management of several types of solid cancers,including lung cancer,by boosting the body's natural tumor killing response.However,it is undeniable that only a small proportion of non-small cell lung cancer(NSCLC)patients with epidermal growth factor receptor(EGFR)mutations can achieve long-term responses and benefit from immunotherapy.CASE SUMMARY Herein,we report the case of a 48-year-old man diagnosed with stage IV lung adenocarcinoma with an EGFR L858R mutation who was administered pembrolizumab monotherapy followed by pemetrexed and achieved a 10-month progression-free survival interval.In this case report,we show that ICIs were effective for our patient with EGFR-mutated NSCLC and discuss the characteristics of patients who can benefit from immunotherapy.CONCLUSION We suggest that patients with EGFR-mutated NSCLC with high PD-L1 expression(defined as≥25%),the L858R mutation,smoking history,or pemetrexed pretreatment may benefit from immunotherapy.

Epidermal growth factor receptor tyrosine kinase inhibitors for non-small cell lung cancer

First-generation epidermal growth factor receptor tyrosine kinase inhibitors(EGFR-TKIs), including gefitinib and erlotinib, have proven to be highly effective agents for advanced non-small cell lung cancer(NSCLC) in patients harboring an activating EGFR mutation such as the exon 19 deletion mutation and L858 R. Although those reversible small molecular targeted agents provide a significant response and survival benefit, all responders eventually acquire resistance. Secondgeneration EGFR-targeting agents, such as irreversible EGFR/HER2 tyrosine kinase inhibitors and pan-HER TKIs, may improve survival further and be useful for patients who acquired resistance to first-generation EGFR-TKIs. This review discusses novel therapeutic strategies for EGFR-mutated advanced NSCLC using first- and second-generation EGFR-TKIs.

Low Correspondence of EGFR Mutations in Tumor Tissue And Paired Serum of Non-Small-Cell Lung Cancer Patients

Objective： Epidermal growth factor receptor （EGFR） mutations are strong determinants of tumor response to EGFR tyrosine kinase inhibitors in non-small-cell lung cancer （NSCLC） patients. The aim of this study was to evaluate the correspondence between EGFR mutations in non-small-cell lung cancer tissues and in circulating DNA. Methods： The research was conducted in 50 non-small-cell lung cancer patients who had undergone curative surgery, and in whom both serum and neoplastic tissues were available. Meanwhile sera of 33 cases of advanced NSCLC patients were also analyzed. DNA were extracted from each sample. Mutations of EGFR in exonl8-21 were examined by PCR amplification method and direct sequencing. Results： EGFR mutations were detected in 15 （30%） of 50 neoplastic tissue samples, 6 cases were in-frame deletion del E746-A750 in exonl9, 9 cases were substitution in exon 21 （all were L858R except one was L861Q）, but no mutated DNA resulted in paired serum circulating DNA samples of 50 resectable patients. As the 33 advanced NSCLC patients, EGFR mutations were detected in only 2 serum circulating DNA samples, all were L858R mutation in exon 21. Conclusion： These data indicated that it was difficult to identify EGFR mutations in circulating DNA of NSCLC patients. The use of EGFR mutation in serum as a clinical method for decision making of TKI therapy is unsatisfactory.

Efficacy of EGFR Tyrosine Kinase Inhibitors in Non-small Cell Lung Cancer Patients Harboring Different Types of EGFR Mutations:A Retrospective Analysis

With the development of molecular pathology, many types of epidermal growth factor receptor（EGFR） mutations have been identified. The efficacy of EGFR tyrosine kinase inhibitors（EGFR-TKIs） in non-small cell lung cancer（NSCLC） patients with different types of EGFR mutations, especially in patients with single rare mutations or complex mutations（co-occurrence of two or more different mutations）, has not been fully understood. This study aimed to examine the efficacy of EGFR-TKIs in NSCLC patients with different types of EGFR mutations. Clinical data of 809 NSCLC patients who harbored different types of EGFR mutations and treated from January 2012 to October 2016 at Renmin Hospital and Zhongnan Hospital, Wuhan, were retrospectively reviewed. The clinical characteristics of these patients and the efficacy of EGFR-TKIs were analyzed. Among these patients, 377 patients had only the EGFR del-19 mutation, 362 patients the EGFR L858R mutation in exon 21, 33 patients single rare mutations and 37 patients complex mutations. Among these 809 patients, 239 patients were treated with EGFR-TKIs. In all the 239 patients, the disease control rate（DCR） was 93.7% with two patients（0.2%） achieving complete response（CR）, the median progression free survival（PFS） was 13.0 months（95% confidence interval [CI], 11.6–14.4 months）, and the median overall survival（OS） was 55.0 months（95% CI, 26.3–83.7 months）. Subgroup analysis revealed that the DCR in patients harboring single rare or complex mutations of EGFR was significantly lower than in those with del-19 or L858 R mutation（P〈0.001）. Patients with classic mutations（del-19 and/or L858 R mutations） demonstrated longer PFS（P〈0.001） and OS（P=0.017） than those with uncommon mutations（single rare and/or complex mutations）. Furthermore, the patients with single rare mutations had shorter median OS than in those with other mutations. Multivariate Cox regression analysis identified that the type of EGFR mutations was an independent risk factor for PFS（hazard ratio [HR]=0.308, 95% CI, 0.191–0.494, P〈0.001） and OS（HR=0.221, 95% CI, 0.101–0.480, P〈0.001）. The results suggest that the single rare or complex EGFR mutations confer inferior efficacy of EGFR-TKIs treatment to the classic mutations. The prognosis of the single rare EGFR mutations is depressing. EGFR-TKIs may be not a good choice for NSCLC patients with single rare mutations of EGFR. Further studies in these patients with uncommon mutations（especially for the patients with single rare mutations） are needed to determine a better precision treatment.

Identification of EGFR kinase domain mutations among lung cancer patients in China:implication for targeted cancer therapy

Lung cancer is one of the leading causes of death with one of the lowest survival rates. However, a subset of lung cancer patients who are of Asian origin and carry somatic mutations in epidermal growth factor receptor or EGFR have responded remarkable well to two tyrosine kinase inhibitors, gefitinib and erlotinib. While EGFR mutation profiles have been reported from Japan, South Korea, and Taiwan, there is no such report from mainland of China where the largest pool of patients reside. In this report, we identified ten somatic mutations from a total of 41 lung cancer patients in China. Among them, seven mutations were found in 17 adenocarcinomas. In contrast to previous reports, eight of these mutations are deletions in exon 19 and two of these deletions are homozygous. These results suggest that a large portion of Chinese adenocarcinoma patients could benefit from gefitinib or erlotinib. This unique mutation profile provides a rationale to develop the next generation of EGFR inhibitors more suitable for the Chinese population.

Management of tyrosine kinase inhibitor resistance in lung cancer with EGFR mutation

The identification of driver mutations and drugs that inhibit their activity has been a major therapeutic advance for patients with advanced lung adenocarcinoma. Unfortunately, the success of these drugs is limited by the universal development of resistance. Treatment failure can result from inadequate drug exposure or selection of resistant malignant clones. Clinically distinct mechanisms of disease progression have been identified and can inform treatment decisions. Investigations into the biochemical mechanisms of tyrosine kinase inhibitor resistance may provide additional therapeutic targets by which the efficacy of targeted therapy can be improved.

The relationship between tyrosine kinase inhibitor therapy and overall survival in patients with non-small cell lung cancer carrying EGFR mutations

For patients with epidermal growth factor receptor (EGFR) mutation-positive lung cancer, the relationship between the dose or duration of treatment with tyrosine kinase inhibitor (TKI) and overall survival remains unclear. Here, we analyzed clinical data of 39 patients who were diagnosed with EGFR mutation-positive non-small cell lung cancer and treated with TKI, but subsequently died. Several parameters were measured in this study: overall survival; first, second, and overall TKI therapy durations; first TKI intensity (actual dose/normal dose); and TKI rate (overall TKI therapy duration/overall survival). The response rate to TKI therapy was 50% , and the median survival was 553 days. After TKI therapy failed, 38.5% patients were re-challenged with TKI. We observed a moderate relationship [r = 0.534, 95% confidential interval (CI) = 0.263 to 0.727, P < 0.001] between overall TKI therapy duration and overall survival. However, we found no relationship between overall survival and first TKI intensity (r = 0.073, 95% CI = -0.380 to 0.247, P = 0.657) or TKI rate (r = 0.0345, 95% CI = -0.284 to 0.346, P = 0.835). Nonsmall cell lung cancer patients with mutation-positive tumors remained on TKI therapy for, on average, 33% of the overall survival time. These findings suggest that patients with EGFR mutation-positive tumors should not stick to using TKIs.

Is EGFR gene mutation testing necessary in smokers with non-small cell lung cancer?

Objective Previous studies have proven that cumulative smoking dose predicts the prevalence of epidermal growth factor receptor(EGFR) mutations. The aim of this study was to investigate the relationship between smoking-related factors and EGFR mutation status. Methods Samples were collected from 195 smokers with non-small cell lung cancer(NSCLC) who underwent surgical resection and the presence of EGFR mutations(exons 19 and 21) were determined by real-time polymerase chain reaction(RT-PCR).Results EGFR gene mutations were present in 33(16.9%) patients who were smokers; the patients were divided into three groups according to the smoking index(SI). The incidence of EGFR mutations decreased from 38.9% in mild smokers to 8.1% in severe smokers(P = 0.001). Compared to daily smoking dose(P = 0.547), initial smoking age(P = 0.085) and duration of smoking history had a larger effect on EGFR mutation status(P = 0.002).Conclusion Although there is a decrease in the incidence of mutations with increasing SI, there were still around 17% of smokers with NSCLC that harbored EGFR mutations, so it is necessary to test for EGFR mutation status in smokers with NSCLC.

Predictive factors associated with gefitinib response in patients with advanced non-small-cell lung cancer(NSCLC)

Purpose： A number of different clinical characteristics have been reported to singly correlate with therapeutic activity of epidermal growth factor receptor （EGFR） tyrosine kinase inhibitors （TKIs） in advanced non-small-cell lung cancer （NSCLC）. This study aimed to identify predictive factors associated with prognostic benefits of gefitinib. Patients and methods： EGFR gene typing in 33 advanced NSCLC patients received gefitinib （250 mg/day） were analyzed with mutant-enriched PCR assay. Gefitinib response was evaluated with potential predictive factors retrospectively. Results： The overall objective response rate （ORR） and median progression-flee survival （PFS） in the 33 patients treated by gefitinib were 45.5% and 3.0 （2.0-4.0） months. The ORR and median PFS in EGFR gene mutation patients were significantly higher/longer than those in EGFR gene wild-type patients （P〈0.01）. Similarly, the ORR and median PFS in non-smoker patients were significantly higher/longer than those in smoker patients （P〈0.05, P〈0.01, respectively）. However, no difference for ORR and median PFS occurred between male and female patients. Logistic multivariate analysis showed that only EGFR mutated gene was significantly associated with the ORR （P〈0.01）. Both EGFR mutated gene and non-smoker were the major factors that contributed to PFS （P〈0.05）. Conclusions： EGFR mutated gene and non-smoker status are potential predictors for gefitinib response in NSCLC patients.

Icotinib, an EGFR-TKI, for the treatment of brain metastases in non-small cell lung cancer:a retrospective study

Objective Treatment of brain metastases from non-small cell lung cancer(NSCLC) is a challenge because of the poor prognosis. Icotinib is a new type of oral epidermal growth factor receptor(EGFR) tyrosine kinase inhibitor(TKI) used in the treatment of advanced NSCLC. The aim of this study was to evaluate the efficacy of icotinib in NSCLC patients with brain metastasis.Methods This study reviewed records of 51 NSCLC patients with brain metastases who took icotinib 125 mg, 3 times a day. Response rate, progression free survival, and overall survival were analyzed. SPSS software version 17.0 was used for univariate analysis, and Cox regression analysis to analyze factors affecting survival. Results Thirty-six cases had partial response, 6 cases had stable disease, and 10 cases had progressive disease. In 31 cases, EGFR gene mutation test were performed. EGFR was mutated in 26 cases and was with wild-type in 5 cases. In patients with EGFR mutations, 23 patients responded to icotinib [the disease control rate(DCR) was 88.5%], significantly higher than in patients with wild-type EGFR(1 patient, DCR 20%)(P = 0.005). The overall median progression-free survival(PFS) was 7.6 months. PFS was longer in the patients with EGFR mutations than in those with wild type EGFR(7.8 months vs 1.2 months, P = 0.03). The overall median overall survival(OS) time was 10.7 months. OS was longer in patients with EGFR mutations than in those with wild type EGFR(15.1 months vs 6.7 months, P = 0.003). The main side effects of the treatment were skin rash and diarrhea; no stage 3 or 4 toxic effects occurred. Univariate analysis demonstrated that OS was related to sex, Eastern Cooperative Oncology Group performance status(ECOG PS), smoking history, and EGFR mutation. Multivariate analysis showed that OS was independently related to sex, ECOG PS, and EGFR mutations.Conclusion Icotinib has a favorable effect on NSCLC patients with brain metastases harboring EGFR mutations. Icotinib can be a new choice of treatment for brain metastases in patients with NSCLC harboring EGFR mutations.

Pharmacogenomics of EGFR-targeted therapies in non-small cell lung cancer:EGFR and beyond

Commonly observed aberrations in epidermal growth factor receptor(EGFR) signaling have led to the development of EGFR-targeted therapies for various cancers,including non-small cell lung cancer(NSCLC).EGFR mutations and overexpression have further been shown to modulate sensitivity to these EGFR-targeted therapies in NSCLC and several other types of cancers.However,it is clear that mutations and/or genetic variations in EGFR alone cannot explain all of the variability in the responses of patients with NSCLC to EGFR-targeted therapies.For instance,in addition to EGFR genotype,genetic variations in other members of the signaling pathway downstream of EGFR or variations in parallel receptor tyrosine kinase(RTK) pathways are now recognized to have a significant impact on the efficacy of certain EGFR-targeted therapies.In this review,we highlight the mutations and genetic variations in such genes downstream of EGFR and in parallel RTK pathways.Specifically,the directional effects of these pharmacogenetic factors are discussed with a focus on two commonly prescribed EGFR inhibitors:cetuximab and erlotinib.The results of this comprehensive review can be used to optimize the treatment of NSCLC with EGFR inhibitors.Furthermore,they may provide the rationale for the design of subsequent combination therapies that involve the inhibition of EGFR.

Comparison of three methods for detecting epidermal growth factor receptor mutations in plasma DNA samples of Chinese patients with advanced non-small cell lung cancer

Background Epidermal growth factor receptor （EGFR） mutations can predict tumor response to tyrosine kinase inhibitors （TKIs）. Detecting EGFR mutations in plasma DNA samples in patients with advanced non-small cell lung cancer is challenging and promising. We compared three methods for detecting plasma EGFR mutations, including direct DNA sequencing, denaturing high-performance liquid chromatography （DHPLC） and Scorpions Amplification Refractory Mutation System （Scorpions ARMS）.Methods Plasma DNA samples from 73 patients with stage ⅢB to Ⅳ adenocarcinoma were analyzed for EGFR mutations in exons 19 （deletion mutation） and 21（L858R mutation） using direct DNA sequencing, DHPLC and Scorpions ARMS. Sensitivities of the three methods were compared and the relationship between EGFR mutations and patients＇survival was analyzed.Results In 73 patients, we detected EGFR mutations in 5 samples （6.9%） by direct DNA sequencing, in 22 samples （30.1%） by DHPLC, and in 28 samples （38.4%） by Scorpions ARMS. EGFR mutations were found in 13 samples in exon 19 and in 9 samples in exon 21 by DHPLC, while we found mutations in 15 samples in exon 19 and in 13 samples in exon 21 by Scorpions ARMS. Among the 73 patients, there was 90.4% concordance between DHPLC and Scorpions ARMS （66/73, K=0.79, P=0.07）. Of the 73 patients, 46 patients were treated with gefitinib, including 18 patients with mutations and 28 patients without mutations as determined by Scorpions ARMS. The 18 patients with mutations had a significantly longer progression-free survival （PFS） time （median PFS was 21.0 months） than the 28 patients without mutations （median PFS was 7.0 months） （P=0.022）.Conclusions Among the three methods for detecting EGFR mutations in plasma DNA samples of patients with advanced lung adenocarcinoma, direct gene sequencing had the lowest sensitivity, while Scorpion ARMS showed the highest mutation detecting capability. DHPLC is slightly less sensitive than Scorpion ARMS. EGFR mutations in exons 19（deletion mutation） and 21 （L858R mutation） predict a longer PFS.

EGFR inhibitors sensitize non-small cell lung cancer cells to TRAIL-induced apoptosis

Apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand(TRAIL) can be regulated by the epidermal growth factor(EGF) signaling pathway.In this study,recombinant adenoviral vectors that encode TRAIL gene from the hTERT/RGD promoter(AdTRAIL) was combined with drugs including gefitinib,elotinib,and cetuximab that inhibit EGFR and the EGF signaling pathway in non-small cell lung cancer(NSCLC) cell lines to investigate their antitumor activity.In vitro,compared to single reagent,AdTRAIL combined with EGFR inhibitors reduced proliferation and enhanced apoptosis in H460,A549,and SW1573 cell lines.Western blot results suggested that these effects were relative to up-regulation of pro-apoptosis protein BAX and down-regulation of p-AKT.In vivo,AdTRAIL combined with cetuximab resulted in a significant growth reduction in H460 xenografts without damage to the main organs of nude mice.Histological examination and TUNEL analyses of xenografts showed that cetuximab enhanced cell apoptosis induced by AdTRAIL.These results indicate that EGFR inhibitors enhanced AdTRAIL anti-tumor activity in NSCLC cell lines and that inhibiting the AKT pathway played an important role in this enhancement.

Effect of EGFR-TKI retreatment following chemotherapy for advanced non-small cell lung cancer patients who underwent EGFR-TKI

Objective:Non-small cell lung cancer(NSCLC)patients with epidermal growth factor receptor(EGFR)-activating mutations have higher response rate and more prolonged survival following treatment with single-agent EGFR tyrosine kinase inhibitor(EGFR-TKI)compared with patients with wild-type EGFR.However,all patients treated with reversible inhibitors develop acquired resistance over time.The mechanisms of resistance are complicated.The lack of established therapeutic options for patients after a failed EGFR-TKI treatment poses a great challenge to physicians in managing this group of lung cancer patients.This study evaluates the influence of EGFR-TKI retreatment following chemotherapy after failure of initial EGFR-TKI within at least 6 months on NSCLC patients.Methods:The data of 27 patients who experienced treatment failure from their initial use of EGFR-TKI within at least6 months were analyzed.After chemotherapy,the patients were retreated with EGFR-TKI(gefitinib 250 mg qd or erlotinib150 mg qd),and the tumor progression was observed.The patients were assessed for adverse events and response to therapy.Targeted tumor lesions were assessed with CT scan.Results:Of the 27 patients who received EGFR-TKI retreatment,1(3.7%)patient was observed in complete response(CR),8(29.6%)patients in partial response(PR),14(51.9%)patients in stable disease(SD),and 4(14.8%)patients in progressive disease(PD).The disease control rate(DCR)was 85.2%(95%CI:62%-94%).The median progression-free survival(m PFS)was 6 months(95%CI:1-29).Of the 13 patients who received the same EGFR-TKI,1 patient in CR,3 patients in PR,8 patients in SD,and 2 patients in PD were observed.The DCR was 84.6%,and the m PFS was 5 months.Of the 14 patients who received another EGFR-TKI,no patient in CR,6 patients in PR,6 patients in SD,and 2 patients in PD were observed.The DCR was 85.7%,and the m PFS was 9.5 months.Significant difference was found between the two groups in PFS but not in response rate or DCR.Conclusion:Retreatment of EGFR-TKIs can be considered an option after failure of chemotherapy for patients who were previously controlled by EGFR-TKI treatment.

Advances in the management of acquired resistance to EGFR-TKI in non-small cell lung cancer

Drugs that specifically target the tyrosine kinase domain of epidermal growth factor receptor(EGFR), such as erlotinib or gefitinib, have exhibited striking efficacy in non-small cell lung cancer(NSCLC) patients harboring activating EGFR mutations. However, acquired resistance inevitably develops and remains a serious barrier for the successful management of patients with this disease. Multiple mechanisms are reportedly involved in the process of acquired resistance, which provide new insights into the management of EGFRtyrosine kinase inhibitor(EGFR-TKI) resistance. Here, we provide an overview of the emerging treatment approaches for patients with EGFR-TKI resistance.

FDG-PET for predicting efficacy of EGFR-tyrosine kinase inhibitors in lung cancer

Non-small cell lung cancer(NSCLC) is the major cause of cancer-related deaths worldwide. Recent advances in molecular biology have resulted in the clinical use of several molecularly targeted drugs, which usually exhibit cytostatic antitumor activity, to improve the survival of NSCLC patients. The epidermal growth factor receptortyrosine kinase inhibitors(EGFR-TKIs) gefitinib and erlotinib have been approved for the treatment of NSCLC, and several phase Ⅲ trials have demonstrated that sensitizing EGFR mutations are biomarkers for predicting a favorable clinical outcome of NSCLC patients treated with the EGFR-TKIs. The Response Evaluation Criteria in Solid Tumors is generally used to assess the therapeutic response to antitumor drugs based on the morphological changes in tumor size as evaluated by computed tomography or magnetic resonance imaging. However, such assessment may not always reflect the treatment efficacy of cytostatic drugs, such as EGFR-TKIs. In this regard, functional imaging methods, including 18F-fluorodeoxyglucose measured by positron emission tomography(FDG-PET), are potentially beneficial. An increasing body of evidence indicates the usefulness of FDG-PETto predict treatment efficacy for NSCLC patients treated with EGFR-TKIs. In this review, we summarize the current understanding of the potential role of FDG-PET in the clinical use of EGFR-TKIs for NSCLC.

Relationship between molecular changes in epidermal growth factor receptor(EGFR)and anaplastic lymphoma kinase(ALK)mutations in lung adenocarcinoma

Objective This study aimed to analyze the relationship between the mutations in epidermal growth factor receptor(EGFR)and anaplastic lymphoma kinase(ALK)and their impact on the prognosis and treatment of lung adenocarcinoma.Methods A total of 158 cases of lung adenocarcinoma reported between January 2007 and January 2014 were retrospectively analyzed.These tumors were resected using radical pneumonectomy and underwent pathology-based diagnosis at our institution(Inner Mongolia People’s Hospital,Hohhot,China).The tissue sections were evaluated using the updated World Health Organization classification of lung adenocarcinomas(2015 version),with each histological component recorded in 5%increments.The histological subtypes were classified,and any surviving cases were followed up.The reverse transcription-polymerase chain reaction(RT-PCR)and direct DNA sequencing were used to evaluate mutations in exons 18,19,20,and 21 in the EGFR gene,and the echinoderm microtubule-associated protein-like 4 gene-ALK variant(EML4-ALK)fusions were detected using sequencing.Results Our cohort included 25 patients with pre-invasive adenocarcinoma,13 patients with lepidic,66 patients with acinar,13 patients with papillary,and 25 patients with solid infiltrative adenocarcinoma with the remaining cases presenting with a variety of pathological subtypes.The prognosis of each histological subtype was different with the 5-year disease-free survival and 5-year overall survival(OS)of pre-invasion adenocarcinoma at 100%;the 5-year OS of lepidic,acinar,and papillary adenocarcinoma patients was only 84.6%,72.7%,and 76.9%,respectively.The 5-year OS of solid and mucinous adenocarcinomas were 32.0%and 36.4%,respectively.EGFR mutation was detected in 69 cases with a mutation rate of 43.7%and majority of these mutations were found in exons 19(50.6%)and 21(37.9%),with women and non-smokers shown to experience a higher mutation rate(P<0.05).However,histological subtype analysis showed that EGFR mutations were primarily found in adenocarcinomas.Most of these mutations were found in lepidic(53.8%)or acinar adenocarcinomas(50.0%),whereas these mutations were rare in both solid(28.0%)and mucinous adenocarcinoma(27.2%).The fusion mutation rate in the EML4-ALK gene was 5.69%,and was most common in young,nonsmoking patients(P<0.05).Conclusion The prognosis of patients in each lung adenocarcinoma subtype is different,and these outcomes are likely related to mutations in the EGFR and EML4-ALK genes.EGFR mutation rates are higher in lepidic and acinar adenocarcinomas,whereas EML4-ALK gene fusion mutations are more common in solid and mucinous adenocarcinoma.EGFR mutations are more common in female and non-smoking patients,whereas EML4-ALK fusions are more common in young,non-smoking patients.