Differential sensitivities to tyrosine kinase inhibitors in NSCLC harboring EGFR mutation and ALK translocation

Epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) translocations in non-small cell lung cancer (NSCLC) are mutually exclusive. However, several exceptional cases harboring both genetic alterations have been reported. In this study, a total of 444 patients with lung adenocarcinoma were examined for their EGFR and ALK status at Seoul National University Hospital between July 2008 and September 2011. EGFR mutations and ALK translocations were detected in 228 (51.4%) and 34 (7.7%) patients, respectively. Four patients (0.9%) had both genetic alterations and three underwent curative surgery. One patient who received both EGFR tyrosine kinase and ALK inhibitors, separately showed an objective response to the ALK inhibitor alone. Considering our and previous studies, patients harboring both EGFR mutation and ALK translocation showed differential sensitivities to both targeted therapies, suggesting a variable dependence on EGFR and ALK oncogenes.     

The use of first-generation tyrosine kinase inhibitors in patients with NSCLC and somatic EGFR mutations

Initial studies with the first-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors gefitinib and erlotinib in patients with non-small cell lung cancer (NSCLC) showed that, although most did not have an objective radiographic response, a minority of patients had dramatic and durable clinical and radiographic responses. The discovery of EGFR mutations in tumours from patients with NSCLC and the association of these mutations with clinical response to gefitinib and erlotinib provided an opportunity to tailor treatment to the mutation profile of the tumour. A number of retrospective reviews and prospective trials have established that gefitinib or erlotinib therapy leads to radiographic responses in approximately 75-80% of patients with NSCLC with EGFR mutations. Although a variety of mutations in EGFR have been identified, the two most common somatic activating EGFR mutations are the LREA deletions in exon 19 and the L858R substitution in exon 21. Together, these mutations make up 85-90% of EGFR mutations. At least two retrospective reviews have indicated a difference in the outcome of patients with different EGFR mutations: after treatment with gefitinib or erlotinib, patients with exon 19 deletions have an increased survival compared with those patients whose tumours have an L858R substitution. These findings remain to be confirmed in prospective studies. Improved understanding of the association of EGFR mutations with clinical outcome may improve the ability of physicians to match treatment to mutation status for patients with NSCLC.     

Disappearance of an activated EGFR mutation after treatment with EGFR tyrosine kinase inhibitors

A 34-year-old Japanese woman presented with left supraclavicular lymph node swelling. Computed tomography scans revealed a mass on the left lower lobe, pulmonary nodules, and pleural effusion. A lymph node biopsy revealed large-cell carcinoma with an epidermal growth factor receptor (EGFR) deletion mutation, L747-T751 in exon 19. Although malignant pleural effusions carried the same EGFR mutation, progressive pleural effusions after treatment with chemotherapy, gefitinib, and erlotinib did not show any EGFR mutation. A cell line established from the pleural effusion 3 days before the patient expired also did not harbor the EGFR mutation. Histological sections of the lymph node of the patient were similar to those of the xenograft tumor of the cell line. There may be genetic heterogeneity in EGFR mutant tumors.     

Prediction of effectiveness of EGFR tyrosine kinase inhibitors for the patients with by EGFR mutations

EGFR-TKI has been synthesized as a potential target for cancer therapy because EGFR is overexpressed and associated with poor prognosis of lung cancer. It was reported that EGFR mutations were more sensitive to EGFRTKI than those without the mutations among lung cancer patients. A subgroup of patients of Asian origin, female sex, adenocarcinoma, and no history of smoking were significantly associated with a high rate of EGFR mutations. These patients with EGFR mutations were not only favorable responders but also had a longer survival than without. In this article, we discuss the EGFR-TKI predictive factors by EGFR mutations.     

Clinical implications of T790M mutation in patients with acquired resistance to EGFR tyrosine kinase inhibitors

Objectives

Although T790M mutation is considered to be the major mechanism of acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in patients with non-small cell lung cancer (NSCLC), its clinical implication remains undetermined.

Methods

Post-progression tumor specimens were prospectively collected for T790M mutation analysis in NSCLC patients with acquired resistance to initial EGFR TKIs. Clinical features were compared between patients with and without T790M.

Results

Out of 70 cases, 36 (51%) were identified to have T790M mutation in the rebiopsy specimen. There was no difference in the pattern of disease progression, progression-free survival for initial TKIs (12.8 and 11.3 months), post-progression survival (14.7 and 14.1 months), or overall survival (43.5 and 36.8 months) in patients with and without T790M. In total, 34 patients received afatinib after post-progression biopsy as a subsequent treatment, and the response rate was 18%. The median progression-free survival for afatinib was 3.7 months for the entire group, and 3.2 and 4.6 months for the groups with and without T790M, respectively (P = 0.33).

Conclusions

The identification of T790M as acquired resistance mechanism was clinically feasible. Although T790M had no prognostic or predictive role in the present study, further research is necessary to identify patients with T790M-mutant tumors who might benefit from newly developed T790M-specific TKIs.     

Clinical studies with non-iressa EGFR tyrosine kinase inhibitors

During the last five years there has been interest in developing non-cytotoxic, targeted cancer treatments. This phenomenon has occurred as a result of increased information regarding factors which regulate tumor proliferation, survival, angiogenesis, invasiveness, and metastatic potential. In non-small cell lung cancer many investigators have focused their attention on the epidermal growth factor receptor (EGFR) because this membrane protein, which has an extracellular ligand binding domain, as well as, tyrosine kinase activity on the intracellular portion of the molecule, is expressed in a relatively high proportion of non-small cell lung cancers. Gefitinib which was the first EGFR specific tyrosine kinase inhibitor to be extensively tested in non-small cell lung cancer has shown single agent activity in non-small cell lung cancer. Subsequently, erlotinib, another EGFR specific tyrosine inhibitor, has also demonstrated single agent activity in non-small cell lung cancer. Phase III trials of erlotinib alone or in combination with chemotherapy have been completed, and data are being analyzed. Several dual inhibitors of erb B1 and erb B2 (PKI 166, GW 572016, EKB 569) have been or are being tested in phase I trials. In addition, CI 1033, a pan-erb inhibitor, is also being tested in phase I studies. Diarrhea and rash have been the predominant side effects of these agents. Life threatening toxicity has been rare. Although the erb tyrosine kinase inhibitors are attrative agents to use in treating non-small cell lung cancer because of their relatively benign toxicity profile, more data are needed to define the role of these agents in non-small cell lung cancer.     

EGFR mutation heterogeneity and the mixed response to EGFR tyrosine kinase inhibitors of lung adenocarcinomas

Background.

Non-small cell lung cancer patients with epidermal growth factor receptor (EGFR) mutations have mixed responses to tyrosine kinase inhibitors (TKIs). Intertumor heterogeneity in EGFR mutations is one potential explanation for this phenomenon.

Methods.

We performed direct sequencing to identify EGFR mutations in 180 pairs of lung adenocarcinoma samples (from 3,071 patients). The high-resolution melting method was used in discordant cases to confirm EGFR mutation status. Matching samples were divided into four groups: primary lesions detected at different times, primary tumors with matched metastatic lymph nodes, multiple pulmonary nodules, and primary tumors with matched distant metastases. Multivariate analyses were performed to evaluate correlations between heterogeneity and patient characteristics.

Results.

In the study population, the discordance rate was 13.9% (25 of 180). The multiple pulmonary nodules group had the highest discordance rate of 24.4% (10 of 41; odds ratio for heterogeneity in primary lesions detected at different times, 6.37; 95% confidence interval, 1.71–23.72; p = .006). Discordance rates in the metachronous and synchronous settings were 15.7% (22 of 140) and 7.5% (three of 40), respectively. In the 34 patients who developed EGFR TKI resistance, 10 (29.4%) cases exhibited heterogeneity and five (14.7%) patients exhibited a mixed response to the drug. Three (8.8%) of the patients with a mixed response also exhibited discordant EGFR mutations.

Conclusions.

The overall discordance rate of EGFR mutation heterogeneity in Asian patients with pulmonary adenocarcinoma is relatively low, but the rate in patients with multiple pulmonary nodules is significantly higher. This observation may explain the mixed tumor response to EGFR TKIs.     

MET gene amplification or EGFR mutation activate MET in lung cancers untreated with EGFR tyrosine kinase inhibitors

We analyzed MET protein and copy number in NSCLC with or without EGFR mutations untreated with EGFR tyrosine kinase inhibitors (TKIs). MET copy number was examined in 28 NSCLC and 4 human bronchial epithelial cell lines (HBEC) and 100 primary tumors using quantitative real‐time PCR. Positive results were confirmed by array comparative genomic hybridization and fluorescence in‐situ hybridization. Total and phospho‐MET protein expression was determined in 24 NSCLC and 2 HBEC cell lines using Western blot. EGFR mutations were examined for exon 19 deletions, T790M, and L858R. Knockdown of EGFR with siRNA was performed to examine the relation between EGFR and MET activation. High‐level MET amplification was observed in 3 of 28 NSCLC cell lines and in 2 of 100 primary lung tumors that had not been treated with EGFR‐TKIs. MET protein was highly expressed and phosphorylated in all the 3 cell lines with high MET amplification. In contrast, 6 NSCLC cell lines showed phospho‐MET among 21 NSCLC cell lines without MET amplification (p = 0.042). Furthermore, those 6 cell lines harboring phospho‐MET expression without MET amplification were all EGFR mutant (p = 0.0039). siRNA‐mediated knockdown of EGFR abolished phospho‐MET expression in examined 3 EGFR mutant cell lines of which MET gene copy number was not amplified. By contrast, phospho‐MET expression in 2 cell lines with amplified MET gene was not down‐regulated by knockdown of EGFR. Our results indicated that MET amplification was present in untreated NSCLC and EGFR mutation or MET amplification activated MET protein in NSCLC. © 2008 Wiley‐Liss, Inc.     

EGFR tyrosine kinase inhibitors for the treatment of NSCLC in East Asia: present and future

Treatment with one of the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) gefitinib or erlotinib has become an additional option for patients with non-small cell lung cancer (NSCLC). Further investigation clearly demonstrated that a subset of patients show a better response to these agents than the overall patient population: individuals with adenocarcinoma histology, females, never-smokers and those of East Asian origin. The ISEL and BR21 studies showed that East Asian patients had significantly longer survival compared with the total study population after EGFR-TKI treatment. The increased response to EGFR-TKIs observed in East Asian patients can likely be attributed to the higher prevalence of activating EGFR mutations found in these individuals. Data from several studies in Japan, Korea, Taiwan and China support this, showing a high occurrence of activating mutations. Furthermore, in prospective studies of gefitinib in these populations, sensitive activating mutations (deletions in exon 19 or L858R) are associated with high overall response and disease control rates. Within East Asian patients, predictors of response to gefitinib include female sex, adenocarcinoma histology, no smoking history and receiving gefitinib first-line, although there may be an interaction between these factors. All patients eventually develop acquired resistance to the currently available EGFR TKIs. In addition, the presence of EGFR mutations is a useful tool to determine NSCLC patients' prognosis; some studies suggested that this may apply if patients are receiving first-line chemotherapy, not only if they are receiving EGFR-TKIs.     

Setting the benchmark for tailoring treatment with EGFR tyrosine kinase inhibitors

Overexpression and mutational activation of the epidermal growth factor receptor (EGFR) is involved in tumor development and progression in non-small-cell lung cancer (NSCLC). Somatic mutations in the EGFR kinase domain confer high sensitivity to tyrosine kinase inhibitors (TKIs). The two most frequent mutations are the exon 19 deletion and the exon 21 L858R. Distinct EGFR mutations differ in their effect on response and survival to TKIs. We have examined EGFR mutations in more than 1800 stage IV NSCLCs for erlotinib customization as both first- and second-line treatment. EGFR mutations cluster in never-smokers, women and adenocarcinomas, as has been described in multiple retrospective studies. The overall frequency of EGFR mutations in our study was 15% and the response in first- and second-line treatment was 84%. Overall, progression-free survival was 13 months and median survival has not been reached. However, patients with exon 19 deletions showed a significantly longer progression-free survival than those harboring L858R mutations. Despite abundant molecular evidence on the role of EGFR mutations, there is still no general agreement as to their predictive value. To clarify this important issue, the Spanish Lung Cancer Group has opened a Phase III trial comparing erlotinib with chemotherapy in stage IV NSCLC patients with EGFR mutations. This study is open to other European institutions.     

Outcome of advanced NSCLC patients harboring sensitizing EGFR mutations randomized to EGFR tyrosine kinase inhibitors or chemotherapy as first-line treatment: a meta-analysis

BackgroundEpidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) are effective as first-line treatment of advanced non-small-cell lung cancer patients with EGFR mutations (EGFR-M+).Patients and methodsWe conducted a literature-based meta-analysis to quantify the magnitude of benefit with upfront EGFR TKI in EGFR-M+ patients. Meta-regression and sensitivity analyses were also carried out to identify additional predictors of outcome and to assess the influence of trial design.ResultsFive trials (805 patients) were identified (three trials prospectively enrolling EGFR-M+ patients and two retrospective analyses of EGFR-M+ patients). TKI significantly increased progression-free survival (PFS) [hazard ratio (HR) 0.45, 95% confidence interval (CI) 0.36–0.58, P < 0.0001] and overall response rate (ORR) (HR 2.08, 95% CI 1.75–2.46, P < 0.0001)] over chemotherapy, while significantly decreasing neutropenia. No significant difference was observed in overall survival. The rate of exon-19 mutations, female gender, and nonsmoking status were identified as additional predictors of outcome at meta-regression analysis. A significant interaction with trial design was found for both PFS (P = 0.028) and ORR (P = 0.008), suggesting a larger advantage for patients treated within prospective trials.ConclusionsIn EGFR-M+ patients, first-line TKI increase both PFS and ORR by ∼25%, while significantly decreasing toxicity. The role of additional predictive factors and the influence of trial design on the magnitude of the observed benefit warrant further investigation.     

Beyond the TRIBUTE trial: integrating HER1/EGFR tyrosine kinase inhibitors with chemotherapy in advanced NSCLC

Evaluation of: Herbst RS, Prager D, Hermann R et al.: TRIBUTE: 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. 23, 5892-5899 (2005). Patients diagnosed with advanced non-small cell lung cancer have limited therapeutic options. A large, randomized, controlled trial of the human epidermal growth factor receptor tyrosine-kinase inhibitor, erlotinib (Tarceva), plus standard first-line chemotherapy did not meet its primary end point of improved survival in the overall population, but did reveal a striking survival benefit in a subset of patients who had never smoked. There are a number of possible explanations for the lack of overall benefit, including the use of an unselected patient population, the need for alternatives to concurrent administration, and a postulated pathophysiological interaction between erlotinib and chemotherapy. Ongoing studies investigating alternative schedules and sequences of administration with chemotherapy will help clinicians to determine how agents such as erlotinib can best be combined with standard cytotoxic agents.     

Efficacy of EGFR tyrosine kinase inhibitors in patients with EGFR-mutated non-small-cell lung cancer: a meta-analysis of 13 randomized trials

Advanced non-small-cell lung cancer (NSCLC) harboring activating mutations of epidermal growth factor receptor (EGFR) are particularly sensitive to tyrosine kinase inhibitors (TKIs), namely erlotinib and gefitinib. The purpose of this meta-analysis was to evaluate the benefit of EGFR TKIs in EGFR-mutated NSCLCs. Eligible studies included published randomized controlled trials in which erlotinib or gefitinib (alone or with chemotherapy) were compared with standard therapy in 1260 patients with EGFR-mutated NSCLCs who were included in 13 trials. The mutational status was obtained through a retrospective or prospective analysis. Relative risk (RR) was calculated for response rate, and hazard ratios (HRs) were calculated for progression-free and overall survival. EGFR TKIs increase the chance of obtaining an objective response almost 2-fold when compared with chemotherapy (RR, 2.06; 2p < .00001). The response rate was 70% vs. 33.2% in first-line trials. In 3 second-line trials, response rates were 47.4% vs. 28.5%, with a benefit similar to first-line trials (RR, 1.79; 2p = .04). EGFR TKIs reduced the hazard of progression by 70% in all trials (HR, 0.30; 2p < .00001) and by 65% in first-line trials only (HR, 0.35; 2p < .00001). Overall, however, they do not improve survival (HR, 0.96; 2p = .71). NSCLCs harboring EGFR mutations derive greater benefit from erlotinib or gefitinib than from chemotherapy. All patients affected by NSCLC with an EGFR-positive mutation test result must be offered the opportunity to be treated with an EGFR TKI upfront or during the natural course of the disease if not previously exposed.     

Strategies for overcoming resistance to EGFR family tyrosine kinase inhibitors

The first-generation epidermal growth factor receptor tyrosine kinase inhibitors erlotinib and gefitinib have been incorporated into treatment paradigms for patients with advanced non-small cell lung cancer. These agents are particularly effective in a subset of patients whose tumors harbor activating epidermal growth factor receptor mutations. However, most patients do not respond to these tyrosine kinase inhibitors, and those who do will eventually acquire resistance that typically results from a secondary epidermal growth factor receptor mutation (e.g., T790M), mesenchymal-epithelial transition factor amplification, or activation of other signaling pathways. For patients whose tumors have wild-type epidermal growth factor receptor, there are several known mechanisms of initial resistance (e.g., Kirsten rat sarcoma viral oncogene homolog mutations) but these do not account for all cases, suggesting that unknown mechanisms also contribute. To potentially overcome the issue of resistance, next-generation tyrosine kinase inhibitors are being developed, which irreversibly block multiple epidermal growth factor receptor family members (e.g., afatinib [BIBW 2992] and PF-00299804) and/or vascular endothelial growth factor receptor pathways (e.g., BMS-690514 and XL647). In addition, drugs that block parallel signaling pathways or signaling molecules downstream of the epidermal growth factor receptor, such as the insulin-like growth factor-1 receptor and the mammalian target of rapamycin, are undergoing clinical evaluation. As drug resistance appears to be pleomorphic, combinations of drugs or drugs with multiple targets may be more effective in circumventing resistance.     

Role of cMET expression in non-small-cell lung cancer patients treated with EGFR tyrosine kinase inhibitors

BackgroundApproximately 10% of unselected non-small-cell lung cancer (NSCLC) patients responded to the epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) treatment. However, resistance mechanisms are not well understood. We evaluated several potential biological markers of intrinsic EGFR-TKIs-resistance in NSCLC.Materials and methodspAKT, pERK, cSRC, E-cadherin, cMET[pY1003], cMET[pY1230/1234/1235], and cMET[pY1349] immunohistochemistry, cMET FISH analysis, and EGFR-, KRAS-, and cMET mutation analysis were carried out on tumor samples from 51 gefitinib-treated NSCLC patients. Biological parameters and survival end points were compared by univariate and multivariate analyses. cMET expression was also investigated in two additional series of patients. The in vitro antiproliferative activity of gefitinib alone or in combination with hepatocyte growth factor and the cMET antibody DN-30 was assessed in NSCLC cells.ResultsEGFR19 deletion and pAKT expression were significantly associated with response (P < 0.0001) and longer time to progression (TTP) (P = 0.007), respectively. Strong cMET[pY1003] membrane immunoreactivity was expressed in 6% of 149 tumors analyzed and was significantly associated with progressive disease (P = 0.019) and shorter TTP (P = 0.041). In vitro, the DN-30 combination synergistically (CI < 1) enhanced gefitinib-induced growth inhibition in all cMET[pY1003]-expressing cell lines studied.ConclusionsActivated cMET[pY1003] appears to be a marker of primary gefitinib resistance in NSCLC patients. cMET may be a target in treatment of NSCLC.     

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.     

HER2 kinase domain mutation results in constitutive phosphorylation and activation of HER2 and EGFR and resistance to EGFR tyrosine kinase inhibitors

HER2/Neu gene mutations have been identified in lung cancer. Expression of a HER2 mutant containing a G776(YVMA) insertion in exon 20 was more potent than wild-type HER2 in associating with and activating signal transducers, phosphorylating EGFR, and inducing survival, invasiveness, and tumorigenicity. HER2(YVMA) transphosphorylated kinase-dead EGFR(K721R) and EGFR(WT) in the presence of EGFR tyrosine kinase inhibitors (TKIs). Knockdown of mutant HER2 in H1781 lung cancer cells increased apoptosis and restored sensitivity to EGFR TKIs. The HER2 inhibitors lapatinib, trastuzumab, and CI-1033 inhibited growth of H1781 cells and cells expressing exogenous HER2(YVMA). These data suggest that (1) HER2(YVMA) activates cellular substrates more potently than HER2(WT); and (2) cancer cells expressing this mutation remain sensitive to HER2-targeted therapies but insensitive to EGFR TKIs.     

Long-term clinical benefit from salvage EGFR tyrosine kinase inhibitors in advanced non-small-cell lung cancer patients with EGFR wild-type tumors

Background

Erlotinib has been approved for the management of NSCLC patients after failure of the first or subsequent line of chemotherapy. Although the efficacy of erlotinib is clearly associated with the presence of EGFR mutations, there is a subset of patients with EGFR wild-type (EGFRwt) tumors who impressively respond.

Patients and methods

Patients with EGFRwt NSCLC who received salvage (≥2nd line) treatment with erlotinib for a prolonged period (>6 months), were sought from the database of the Hellenic Oncology Research Group. We retrospectively analyzed the clinical, pathological and molecular characteristics of the patients with available tumor material.

Results

Forty-four patients that received erlotinib for >6 months (median 10.1 months) were enrolled in the study. The majority of them were male, never-smokers with adenocarcinoma histology and a good performance status. KRAS and PIK3CA mutations were detected in 21% (9/42 tested) and 13% (4/30 tested) of the patients, respectively. The ALK-EML4 translocation was found in 10% (2/20 tested); there was no patient with HER2 or BRAF mutated tumor. Twelve (54.5%) tumor specimens were considered positive for EGFR-overexpression. Eleven patients experienced a partial response (objective response rate 25%; 95% CI 12–38%) and the remaining 33 had stable disease. The median progression-free survival and overall survival were 10.1 (95% CI 8.6–11.6 months) and 24.1 (95% CI 11.2–37 months), respectively.

Conclusions

Treatment with erlotinib significantly improves the clinical outcome in a subset of NSCLC patients with EGFRwt tumors. Further molecular analysis of such tumor specimens could provide a more comprehensive characterization of this particular group of patients. Nevertheless, the presence of other mutations should not prevent the treating physician from using erlotinib at later lines of salvage therapy for NSCLC patients.

     

EGFR突变晚期非小细胞肺癌免疫治疗的研究进展

肺癌是全球癌症相关死亡的主要原因。表皮生长因子受体是亚洲肺腺癌患者最常见的突变类型。酪氨酸激酶抑制剂是表皮生长因子受体突变非小细胞肺癌一线首选治疗,但获得性耐药限制了其长期疗效,对于耐药后治疗仍没有有效选择方案。目前,免疫治疗延长了部分患者的生存时间,但在表皮生长因子受体突变非小细胞肺癌中反应较差,介导其疗效不佳的原因仍尚不明确。多种生物标志物的联合评价更能准确预测其免疫治疗疗效并筛选潜在获益人群。联合抗血管生成及新型靶点药物治疗具有免疫增敏作用。本文就表皮生长因子受体突变晚期非小细胞肺癌免疫治疗研究现状、免疫治疗潜在获益人群及免疫联合治疗新策略进行综述。