Comprehensive investigation of oncogenic driver mutations in Chinese non-small cell lung cancer patients

Purpose

To determine the frequency of driver mutations in Chinese non-small cell lung cancer (NSCLC) patients.

Methods

Comprehensive mutational analysis was performed in 1356 lung adenocarcinoma, 503 squamous cell carcinoma, 57 adenosquamous lung carcinoma, 19 large cell carcinoma and 8 sarcomatoid carcinoma. The effect of EGFR tyrosine kinase inhibitors (TKIs) on EGFR-mutated lung adenocarcinoma patients after disease recurrence was investigated.

Results

Mutations in EGFR kinase domain, HER2 kinase domain, KRAS, BRAF, ALK, ROS1 and RET were mutually exclusive. In lung adenocarcinoma cases “pan-negative” for the seven above-mentioned driver mutations, we also detected two oncogenic EGFR extracellular domain mutations (A289D and R324L), two HER2 extracellular and transmembrane domain mutations (S310Y and V659E), one ARAF S214C mutation and two CD74-NRG1 fusions. Six (1.2%) FGFR3 activating mutations were identified in lung squamous cell carcinoma (five S249C and one R248C). There were three (15.8%) EGFR mutations and four (21.1%) KRAS mutations in large cell carcinoma. Three (37.5%) KRAS mutations were detected in sarcomatoid carcinoma. In EGFR-mutated lung adenocarcinoma patients who experienced disease recurrence, treatment with EGFR TKIs was an independent predictor of better overall survival (HR = 0.299, 95% CI: 0.172–0.519, P < 0.001).

Conclusion

We determined the frequency of driver mutations in a large series of Chinese NSCLC patients. EGFR TKIs might improve the survival outcomes of EGFR-mutated lung adenocarcinoma patients who experienced disease recurrence.     

PTEN and PIK3CA gene copy numbers and poor outcomes in non-small cell lung cancer patients with gefitinib therapy

Background:

Preclinical studies in non-small cell lung cancer (NSCLC) suggest the interaction of PTEN and PI3K affects sensitivity to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). We investigated outcomes in relation to PTEN, PIK3CA and EGFR gene copy number, and chromosome 7 (CEN7) polysomy in NSCLC patients treated with gefitinib.

Methods:

Fluorescent in situ hybridisation analyses of PTEN, PIK3CA, EGFR and CEN7 were performed on tumour specimens from patients treated on the expanded access gefitinib trial. Progression-free survival (PFS) and overall survival (OS) were correlated with outcomes in all patients and EGFR wild-type patients.

Results:

Progression-free survival (hazard ratio=2.54, P<0.001) and OS (hazard ratio=4.04, P<0.001) were significantly shorter in patients whose tumours had all of the following molecular patterns: CEN7 <4 copies per cell, PTEN loss (<2 copies in at least 20% of cells), and PIK3CA gain (>2 copies in at least 40% of cells) both in all and EGFR wild-type only patients.

Conclusion:

The combination of low CEN7 copy number, PTEN loss, and PI3KCA gain may be useful for identifying NSCLC patients unlikely to benefit from treatment with EGFR (TKIs), specifically in wild-type EGFR cases.     

Phase II Study of Afatinib as Third‐Line Treatment for Patients in Korea With Stage IIIB/IV Non‐Small Cell Lung Cancer Harboring Wild‐Type EGFR

Background.

This phase II single-arm trial evaluated afatinib, an irreversible inhibitor of the ErbB receptor family as third-line treatment of Korean patients with advanced non-small cell lung cancer (NSCLC) and tumors with wild-type EGFR. Currently, no standard therapy exists for these patients.

Methods.

Eligible patients had stage IIIB/IV wild-type EGFR lung adenocarcinoma and had failed to benefit from two previous lines of chemotherapy but had not received anti-EGFR treatment. Patients received oral afatinib at 40 mg per day until disease progression or occurrence of intolerable adverse events (AEs). The primary endpoint was confirmed objective tumor response (OR) rate (confirmed complete response [CR] or partial response [PR]). Secondary endpoints included disease control rate (DCR; OR or stable disease for ≥6 weeks), progression-free survival (PFS), and safety.

Results.

Forty-two patients received afatinib treatment, and 38 of those were included in efficacy analyses. No confirmed CRs or PRs were reported. DCR was 24% (9 of 38 patients), with a median disease control duration of 19.3 weeks. Median PFS was 4.1 weeks (95% confidence interval: 3.9–8.0). Frequently reported AEs (mainly grades 1 and 2) were rash/acne (88%), diarrhea (62%), and stomatitis (57%).

Conclusion.

Heavily pretreated patients with wild-type EGFR NSCLC treated with afatinib monotherapy did not experience an objective response and only 24% had disease stabilization lasting more than 6 weeks. AEs were manageable and consistent with the expected safety profile.     

Assessment of epidermal growth factor receptor and K-ras mutation status in cytological stained smears of non-small cell lung cancer patients: correlation with clinical outcomes

Objective.

Epidermal growth factor receptor (EGFR) and K-ras mutations guide treatment selection in non-small cell lung cancer (NSCLC) patients. Although mutation status is routinely assessed in biopsies, cytological specimens are frequently the only samples available. We determined EGFR and K-ras mutations in cytological samples.

Methods.

DNA was extracted from 150 consecutive samples, including 120 Papanicolau smears (80%), 10 cell blocks (7%), nine fresh samples (6%), six ThinPrep® tests (4%), and five body cavity fluids (3.3%). Papanicolau smears were analyzed when they had >50% malignant cells. Polymerase chain reaction and direct sequencing of exons 18–21 of EGFR and exon 2 of K-ras were performed. EGFR mutations were simultaneously determined in biopsies and cytological samples from 20 patients. Activity of EGFR tyrosine kinase inhibitors (TKIs) was assessed.

Results.

The cytological diagnosis was adenocarcinoma in 110 samples (73%) and nonadenocarcinoma in 40 (27%) samples. EGFR mutations were identified in 26 samples (17%) and K-ras mutations were identified in 18 (12%) samples. EGFR and K-ras mutations were mutually exclusive. In EGFR-mutated cases, DNA was obtained from stained smears in 24 cases (92%), pleural fluid in one case (4%), and cell block in one case (4%). The response rate to EGFR TKIs in patients harboring mutations was 75%. The mutation status was identical in patients who had both biopsies and cytological samples analyzed.

Conclusion.

Assessment of EGFR and K-ras mutations in cytological samples is feasible and comparable with biopsy results, making individualized treatment selection possible for NSCLC patients from whom tumor biopsies are not available.     

Low EGFR/MET ratio is associated with resistance to EGFR inhibitors in non-small cell lung cancer

Purpose

Although activating mutations in the epidermal growth factor receptor (EGFR) gene are predictive markers for response to EGFR inhibitors, 30–40% of EGFR-mutant non-small cell lung cancer (NSCLC) patients are de novo non-responders. Hence, we sought to explore additional biomarkers of response.

Methods

We conducted a prospective pilot study to characterize the expression and/or activation of key receptor tyrosine kinases (RTKs) in stage IIIB-IV NSCLC tumors. A total of 37 patients were enrolled and 34 underwent EGFR inhibitor treatment.

Results

As expected, patients bearing activating EGFR mutations showed increased progression free survival (PFS) compared to patients with wild-type EGFR status (9.3 vs 1.4 months, p = 0.0629). Analysis of baseline tumor RTK profiles revealed that, regardless of EGFR mutation status, higher levels of EGFR relative to MET correlated with longer PFS. At multiple EGFR/MET ratio cut-offs, including 1, 2 and 3, median PFS according to below vs. above cut-offs were 0.4 vs. 6.1 (p = 0.0001), 0.5 vs. 9.3 (p = 0.0006) and 1.0 vs. 11.2 months (p = 0.0008), respectively.

Conclusion

The EGFR/MET ratio measured in tumors at baseline may help identify NSCLC patients most likely to benefit from prolonged PFS when treated with EGFR inhibitors.     

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.     

EGFR and K-Ras mutations in women with lung adenocarcinoma: implications for treatment strategy definition

Background

We aimed at investigating the outcomes of female patients with stage IIIB-IV adenocarcinoma of the lung according to EGFR and K-Ras mutational status.

Methods

One hundred and three consecutive female patients genotyped at a single Italian Institution were analyzed. Patients were planned to receive first-line platinum-based chemotherapy (CT) and a salvage treatment with anti-EGFR tyrosine-kinase inhibitors (TKIs) was proposed irrespective of tumor mutational status. EGFR (exons 18–21) and K-Ras (exon 2, codons 12–13) mutations were evaluated by real-time PCR and pyrosequencing. The association of mutational status with clinical variables and treatment benefit was investigated by chi-square test and log-rank test.

Results

EGFR and K-Ras mutations were found in 31 (30%) and 13 (15%) cases, respectively. Sixty-six patients received platinum CT: no correlation was observed between EGFR or K-Ras mutational status and response rate (RR) (p > 0.05). However, patients treated with first-line CT harboring EGFR activating mutations experienced a significantly reduced progression-free survival (PFS) in comparison with wild-type ones (4.4 vs. 6.4 months, respectively; HR 0.597, 95% CI 0.287-0.975; p = 0.048). Thirty-nine patients received salvage treatment with erlotinib: EGFR activating mutations were significantly correlated with RR (60% vs. 12.5%; p = 0.004) and PFS (11.4 vs. 4.5 months; HR 0.491, 95% CI 0.216-0.936; p = 0.044). Responses to erlotinib were not reported among women with K-Ras mutant tumors, while 50% of those with wild-type K-Ras achieved an objective remission (p = 0.296). Median PFS (3.5 vs. 8.8 months; HR 0.284, 95% CI 0.015-0.510; p = 0.010) and OS (3.9 vs. 19.8 months; HR 0.158, 95% CI 0.001-0.075; p < 0.001) were significantly shorter among K-Ras mutant patients treated with TKI.

Conclusions

In our population of Caucasian women with advanced lung adenocarcinoma we observed that the presence of EGFR activating mutations correlates with a significant reduction in the benefit from first-line platinum-based CT, emphasizing the importance of an upfront use of anti-EGFR TKIs in this patient subset. K-Ras mutations seem to correlate with a detrimental effect from anti-EGFR TKI, but this finding deserves further investigation.     

Receptor Tyrosine Kinase Fusions and BRAF Kinase Fusions are Rare but Actionable Resistance Mechanisms to EGFR Tyrosine Kinase Inhibitors

Introduction

We analyzed a large set of EGFR-mutated (EGFR+) NSCLC to identify and characterize cases with co-occurring kinase fusions as potential resistance mechanisms to EGFR tyrosine kinase inhibitors (TKIs).

EGFR gene copy number assessment from areas with highest EGFR expression predicts response to anti-EGFR therapy in colorectal cancer

Background:

Only 40–70% of metastatic colorectal cancers (mCRCs) with wild-type (WT) KRAS oncogene respond to anti-epidermal growth factor receptor (anti-EGFR) antibody treatment. EGFR amplification has been suggested as an additional marker to predict the response. However, improved methods for bringing the EGFR analysis into routine laboratory are needed.

Methods:

The material consisted of 80 patients with mCRC, 54 of them receiving anti-EGFR therapy. EGFR gene copy number (GCN) was analysed by automated silver in situ hybridisation (SISH). Immunohistochemical EGFR protein analysis was used to guide SISH assessment.

Results:

Clinical benefit was seen in 73% of high (⩾4.0) EGFR GCN patients, in comparison with 59% of KRAS WT patients. Only 20% of low EGFR GCN patients responded to therapy. A high EGFR GCN number associated with longer progression-free survival (P<0.0001) and overall survival (P=0.004). Together with KRAS analysis, EGFR GCN identified the responsive patients to anti-EGFR therapy more accurately than either test alone. The clinical benefit rate of KRAS WT/high EGFR GCN tumours was 82%.

Conclusion:

Our results show that automated EGFR SISH, in combination with KRAS mutation analysis, can be a useful and easily applicable technique in routine diagnostic practise for selecting patients for anti-EGFR therapy.     

Epidermal growth factor receptor tyrosine kinase inhibitors as initial therapy for non-small cell lung cancer: Focus on epidermal growth factor receptor mutation testing and mutation-positive patients

Activation of the epidermal growth factor receptor (EGFR) pathway has been implicated in tumorigenesis in non-small cell lung cancer (NSCLC), the most common type of lung cancer. As a result, EGFR has become a key focus for the development of personalized therapy, with several molecular biomarkers having been investigated as potential predictors of response with EGFR tyrosine kinase inhibitors (TKIs) in NSCLC (e.g., EGFR expression, EGFR gene copy gain, and EGFR mutations). Of these, activating mutations in EGFR have thus far given the most consistent results based on the available evidence from preclinical studies and clinical trials. In an attempt to identify patients who are most likely to benefit from treatment with EGFR TKIs, EGFR mutation testing is being increasingly utilized in clinical practice. Currently in the United States, no EGFR TKI or accompanying mutational test is approved for the identification and first-line treatment of patients with advanced NSCLC. However, the first-generation EGFR TKIs, erlotinib and gefitinib, as well as investigational ErbB family TKIs and EGFR mutation testing methods are being evaluated in this setting. This review will discuss EGFR mutation testing as a biomarker of response to EGFR TKIs and the evolution of EGFR mutational analysis in NSCLC. Completed and ongoing clinical trials evaluating currently available or investigational EGFR TKIs as first-line therapy in molecularly and clinically selected patients with NSCLC, with a focus on trials in patients whose tumors have EGFR mutations, will also be reviewed.     

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.     

Revisiting Clinical Trials Using EGFR Inhibitor-Based Regimens in Patients with Advanced Non-Small Cell Lung Cancer: A Retrospective Analysis of an MD Anderson Cancer Center Phase I Population

Purpose

Single-agent EGFR inhibitor therapy is effective mainly in patients with lung cancer and EGFR mutations. Treating patients who develop resistance, or who are insensitive from the outset, often because of resistant mutations, other aberrations or the lack of an EGFR mutation, probably requires rational combinations. We therefore investigated the outcome of EGFR inhibitor-based combination regimens in patients with heavily-pretreated non-small cell lung cancer (NSCLC) referred to a Phase I Clinic.

Methods

We reviewed the electronic records of patients with NSCLC treated with an EGFR inhibitor-based combination regimen: erlotinib and cetuximab; erlotinib, cetuximab and bevacizumab; erlotinib and dasatinib; erlotinib and bortezomib; or cetuximab and sirolimus.

Results

EGFR mutations were detected in 16% of patients (21/131). EGFR inhibitor-based combination regimens were administered to 15 patients with EGFR-mutant NSCLC and 24 with EGFR wild-type disease. Stable disease (SD) ≥6 months/partial remission (PR) was attained in 20% of EGFR-mutant patients (3/15; two with sensitive mutations and secondary resistance to prior erlotinib, and one with a resistant mutation), as well as 26% of evaluable patients (5/19) with wild-type disease. One of three evaluable patients with squamous cell histology achieved SD for 26.5 months (EGFR wild-type, TP53-mutant, regimen=erlotinib, cetuximab and bevacizumab).

Conclusions

Eight of 34 evaluable patients (24%) with advanced, refractory NSCLC evaluable for response achieved SD ≥6 months/PR (PR=3; SD ≥6 months=5) on EGFR inhibitor-based combination regimens (erlotinib, cetuximab; erlotinib, cetuximab and bevacizumab; and, erlotinib, bortezomib), including patients with secondary resistance to single-agent EGFR inhibitors, resistant mutations, wild-type disease, and, squamous histology.     

Detection of EGFR mutations in circulating free DNA by PNA-mediated PCR clamping

Background

Epidermal growth factor receptor (EGFR)-activating mutations are major determinants in predicting the tumor response to EGFR tyrosine kinase inhibitors in non-small cell lung cancer (NSCLC). Noninvasive test for the detection of EGFR mutations is required, especially in NSCLC patients from whom tissue is not available. In this study, we assessed the feasibility of detection of EGFR mutations in free DNA circulating in plasma.

Methods

Plasma samples of 60 patients with partial response to gefitinib were analyzed to detect EGFR-activating mutations in exons 19 and 21. Forty (66.7%) of patients had tumor EGFR mutation results. EGFR mutations in plasma were detected using the peptide nucleic acid (PNA)-mediated polymerase chain reaction (PCR) clamping method. All clinical data and plasma samples were obtained from 11 centers of the Korean Molecular Lung Cancer Group (KMLCG).

Results

Of the 60 patients, 39 were female and the median age was 62.5 years. Forty-three patients never smoked, 53 had adenocarcinomas, and seven had other histologic types. EGFR-activating mutation was detected in plasma of 10 cases (exon 19 deletion in seven and exon 21 L858R point mutation in three). It could not be found in plasma after treatment for 2 months. When only patients with confirmed EGFR mutation in tumor were analyzed, 17% (6 of 35) of them showed positive plasma EGFR mutation and the mutation type was completely matched with that in tumor. There was no statistically significant difference in clinical parameters between patients with EGFR mutations in plasma and those without EGFR mutations.

Conclusions

The detection rate of EGFR mutations from plasma was not so high despite highly sensitive EGFR mutation test suggesting that more advances in detection methods and further exploration of characteristics of circulating free DNA are required.     

Experience With Afatinib in Patients With Non‐Small Cell Lung Cancer Progressing After Clinical Benefit From Gefitinib and Erlotinib

Background.

Afatinib, an irreversible ErbB family blocker, demonstrated superiority to chemotherapy as first-line treatment in patients with EGFR-mutated non-small cell lung cancer (NSCLC). Afatinib is also active in patients progressing on EGFR tyrosine kinase inhibitors (EGFR-TKIs). We report the results of a large cohort of NSCLC patients receiving afatinib within a compassionate-use program (CUP).

Patients and Methods.

Patients with advanced NSCLC progressing after one line or more of chemotherapy and one line or more of EGFR-TKI treatment with either an EGFR mutation or documented clinical benefit were enrolled. Data collection was not monitored or verified by central review. The intention of this CUP was to provide controlled preregistration access to afatinib for patients with life-threatening diseases and no other treatment option.

Results.

From May 2010 to October 2013, 573 patients (65% female; median age: 64 years [range: 28–89 years]) were enrolled, with strong participation of community oncologists. Comorbidities were allowed, including second malignancies in 11% of patients. EGFR mutation status was available in 391 patients (72%), and 83% tested mutation positive. Median time to treatment failure (TTF) of 541 patients treated with afatinib was 3.7 months (range: 0.0 to >29.0 months). Median TTF was 4.0 and 2.7 months in patients with adenocarcinomas and squamous cell carcinomas, respectively, and 4.6 months in patients with EGFR-mutated NSCLC. Adverse events were generally manageable.

Conclusion.

Afatinib was able to be given in a real-world setting to heavily pretreated patients with EGFR-mutated or EGFR-TKI-sensitive NSCLC. Acknowledging the constraints of data collection in a CUP, afatinib appears to be safe and to confer some clinical benefit in this population.     

Afatinib in Non‐Small Cell Lung Cancer Harboring Uncommon EGFR Mutations Pretreated With Reversible EGFR Inhibitors

Background.

Afatinib, an irreversible ErbB family blocker, is approved for treatment of patients with previously untreated non-small cell lung cancer (NSCLC) harboring activating epidermal growth factor receptor (EGFR) mutations. Efficacy of afatinib in EGFR tyrosine kinase inhibitor-naïve (TKI-naïve) patients with uncommon EGFR mutations (other than exon 19 deletions or exon 21 point mutations) has been reported; however, efficacy in TKI-pretreated patients with uncommon EGFR mutations is unknown.

Materials and Methods.

In the afatinib compassionate use program (CUP), patients with advanced or metastatic, histologically confirmed NSCLC progressing after at least one line of chemotherapy and one line of EGFR-TKI treatment were enrolled. Demographic data, mutation type, response rates, time to treatment failure (TTF), and safety in patients harboring uncommon EGFR mutations were reported.

Results.

In 60 patients (63% female, median age 63 years [range: 30–84 years]), a total of 66 uncommon EGFR mutations including 30 T790M mutations were reported (18.4% and 11%, respectively, of known EGFR mutations within the CUP). Most patients (67%) received afatinib as third- or fourth-line treatment. Median TTF was 3.8 months (range: 0.2 to >24.6 months; p = .244) in patients with uncommon mutations compared with 5.1 months (range: 0.1 to >21.1 months) in patients with common mutations (n = 165). Pronounced activity was observed with E709X mutations (TTF >12 months). No new safety signals were detected.

Conclusion.

Afatinib is clinically active and well tolerated in many TKI-pretreated NSCLC patients harboring uncommon EGFR mutations. Compared with results reported in TKI-naïve patients, activity was also indicated in patients with T790M and exon 20 insertion mutations.

Implications for Practice:

This analysis consists of a large database of non-small cell lung cancer patients with uncommon EGFR mutations who were previously treated with reversible EGFR tyrosine kinase inhibitors. Although indirectly assessed, the results indicate that patients with uncommon EGFR mutations can derive benefit from treatment with the irreversible ErbB family blocker afatinib, even in some cases of tumors harboring resistance-mediating exon 20 mutations. In this study, adverse events were modest and consistent with previous reports on afatinib.     

Continuation of epidermal growth factor receptor tyrosine kinase inhibitor treatment prolongs disease control in non-small-cell lung cancers with acquired resistance to EGFR tyrosine kinase inhibitors

Objectives

Patients with non-small-cell lung cancer (NSCLC) develop acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) after tumor regression. No approved targeted therapies are currently available after initial EGFR TKI treatment. This study investigated the efficacy of continuing EGFR TKI therapy with local treatments for patients with NSCLC and local progression or minimal/slow progression on TKI therapy.

Materials and Methods

Fifty-five patients with NSCLC treated with EGFR TKIs and developed acquired resistance to the drug were included. Initial response to target therapy, median progression free survival (PFS1), progression pattern, and first progression site were assessed. Median progression free survival to physician assessment progression (PFS2) and difference between PFS1 and PFS2 (PFS difference) were also recorded.

Results and Conclusion

PFS1 was 11.2 months, PFS2 was 20.3 months, and PFS difference was 8.3 months. Nineteen patients (34.5%) who manifested progression received local therapy, and 16 (28.6%) underwent rebiopsy after progression with six positive EGFR T790M mutations detected. Cox proportional hazards regression model showed that only the first line of treatment was significantly correlated with PFS difference. NSCLC patients with acquired resistance to EGFR TKIs could benefit from the same TKI therapy through months to years of disease control.     

Antitumor activity of selective MEK1/2 inhibitor AZD6244 in combination with PI3K/mTOR inhibitor BEZ235 in gefitinib-resistant NSCLC xenograft models

Purpose

Although the EGF receptor tyrosine kinase inhibitors (EGFR-TKI) gefitinib have shown dramatic effects against EGFR mutant lung cancer, patients become resistant by various mechanisms, including gatekeeper EGFR-T790M mutation, MET amplification, and KRAS mutation, thereafter relapsing. AZD6244 is a potent, selective, and orally available MEK1/2 inhibitor. In this study, we evaluated the therapeutic efficacy of AZD6244 alone or with BEZ235, an orally available potent inhibitor of phosphatidylinositol 3–kinase (PI3K) and mammalian target of rapamycin (mTOR), in gefitinib-resistant non-small cell lung carcinoma (NSCLC) models.

Experimental design

NCI-H1975 with EGFR-T790M mutation, NCI-H1993 with MET amplification and NCI-H460 with KRAS/PIK3CA mutation human NSCLC cells were subcutaneous injected into the athymic nude mice respectively. Mice were randomly assigned to treatment with AZD6244, BEZ235, AZD6244 plus BEZ235, or control for 3 weeks, then all mice were sacrificed and tumor tissues were subjected to western blot analyses and immunohistochemical staining.

Results

AZD6244 could inhibit the tumor growth of NCI-H1993, but slightly inhibit the tumor growth of NCI-1975 and NCI-H460. Combining AZD6244 with BEZ235 markedly enhanced their antitumor effects and without any marked adverse events. Western blot analysis and immunohistochemical staining revealed that AZD6244 alone reduced ERK1/2 phosphorylation, angiogenesis, and tumor cell proliferation. Moreover, MEK1/2 inhibition resulted in decreased AKT phosphorylation in NCI-H1993 tumor model. BEZ235 also inhibited AKT phosphorylation as well as their downstream molecules in all three tumor models. The antiangiogenic effects were substantially enhanced when the agents were combined, which may due to the reduced expression of matrix metallopeptidase-9 in tumor tissues (MMP-9).

Conclusions

In this study, we evaluated therapy directed against MEK and PI3K/mTOR in distinct gefitinib-resistant NSCLC xenograft models. Combining AZD6244 with BEZ235 enhanced their antitumor and antiangiogenic effects. We concluded that the combination of a selective MEK inhibitor and a PI3K/mTOR inhibitor was effective in suppressing the growth of gefitinib-resistant tumors caused by EGFR T790M mutation, MET amplification, and KRAS/PIK3CA mutation. This new therapeutic strategy may be a practical approach in the treatment of these patients.     

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.     

Afatinib and Cetuximab in Four Patients With EGFR Exon 20 Insertion–Positive Advanced NSCLC

Introduction

EGFR exon 20 insertions comprise 4% to 9% of EGFR mutated NSCLC. Despite being an oncogenic driver, they are associated with primary resistance to EGFR tyrosine kinase inhibitors (TKIs). We hypothesized that dual EGFR blockade with afatinib, an irreversible EGFR TKI, and cetuximab, a monoclonal antibody against EGFR, could induce tumor responses.