Prediction for response duration to epidermal growth factor receptor-tyrosine kinase inhibitors in EGFR mutated never smoker lung adenocarcinoma

A Functional Genomics Review of Non-Small-Cell Lung Cancer in Never Smokers

There is currently a dearth of information regarding lung cancer in never smokers (LCINS). Additionally, there is a difference in somatic mutations, tumour mutational burden, and chromosomal aberrations between smokers and never smokers (NS), insinuating a different disease entity in LCINS. A better understanding of actionable driver alterations prevalent in LCINS and the genomic landscape will contribute to identifying new molecular targets of relevance for NS that will drastically improve outcomes. Differences in treatment outcomes between NS and smokers, as well as sexes, with NSCLC suggest unique tumour characteristics. Epidermal growth factor receptor (EGFR) tyrosine kinase mutations and echinoderm microtubule-associated protein-like 4 anaplastic lymphoma kinase (EML4-ALK) gene rearrangements are more common in NS and have been associated with chemotherapy resistance. Moreover, NS are less likely to benefit from immune mediators including PD-L1. Unravelling the genomic and epigenomic underpinnings of LCINS will aid in the development of not only novel targeted therapies but also more refined approaches. This review encompasses driver genes and pathways involved in the pathogenesis of LCINS and a deeper exploration of the genomic landscape and tumour microenvironment. We highlight the dire need to define the genetic and environmental aspects entailing the development of lung cancer in NS.

The Role of Proteomics and Phosphoproteomics in the Discovery of Therapeutic Targets and Biomarkers in Acquired EGFR-TKI-Resistant Non-Small Cell Lung Cancer

The discovery of potent EGFR-tyrosine kinase inhibitors (EGFR-TKIs) has revolutionized the treatment of EGFR-mutated lung cancer. Despite the fact that EGFR-TKIs have yielded several significant benefits for lung cancer patients, the emergence of resistance to EGFR-TKIs has been a substantial impediment to improving treatment outcomes. Understanding the molecular mechanisms underlying resistance is crucial for the development of new treatments and biomarkers for disease progression. Together with the advancement in proteome and phosphoproteome analysis, a diverse set of key signaling pathways have been successfully identified that provide insight for the discovery of possible therapeutically targeted proteins. In this review, we highlight the proteome and phosphoproteomic analyses of non-small cell lung cancer (NSCLC) as well as the proteome analysis of biofluid specimens that associate with acquired resistance in response to different generations of EGFR-TKI. Furthermore, we present an overview of the targeted proteins and potential drugs that have been tested in clinical studies and discuss the challenges of implementing this discovery in future NSCLC treatment.

A subset of VEGFR-TKIs activates AMPK in LKB1-mutant lung cancer

The mutation of tumor suppressor gene liver kinase B1 (LKB1) has a prevalence of about 20% in non-small cell lung cancer (NSCLC). LKB1-mutant lung cancer is characterized by enhanced aggressiveness and immune escape and is associated with poor prognosis. Therefore, it is urgent to develop effective therapeutic methods for LKB1-mutant NSCLC. Recently, apatinib, a VEGFR-TKI, was found to significantly improve the outcome of LKB1-mutant NSCLC, but the mechanism is not completely clear. In this study, AMP-activated protein kinase (AMPK), the crucial downstream kinase of LKB1 was excavated as the potential target of apatinib. Biochemical experiments verified that apatinib is a direct AMPK activator. Moreover, clinically available VEGFR-TKIs were found to regulate AMPK differently: Apatinib and anlotinib can directly activate AMPK, while axitinib and sunitinib can directly inhibit AMPK. Activation of AMPK by apatinib leads to the phosphorylation of acetyl-CoA carboxylase (ACC) and inhibition of de novo fatty acid synthesis (FAsyn), which is upregulated in LKB1-null cancers. Moreover, the killing effect of apatinib was obviously enhanced under delipidated condition, and the combination of exogenous FA restriction with apatinib treatment can be a promising method for treating LKB1-mutant NSCLC. This study discovered AMPK as an important off-target of apatinib and elucidated different effects of this cluster of VEGFR-TKIs on AMPK. This finding can be the basis for the accurate and combined application of these drugs in clinic and highlights that the subset of VEGFR-TKIs including apatinib and anlotinib are potentially valuable in the treatment of LKB1-mutant NSCLC.

Case Report: PTEN Mutation Induced by anti-PD-1 Therapy in Stage IV Lung Adenocarcinoma

Lung cancer is the most common solid tumor in the worldwide. Targeted therapy and immunotherapy are important treatment options in advanced non-small cell lung cancer (NSCLC). The association of PTEN mutation and tumor immunotherapy is less established for patients with NSCLC. We present the case of an Asian woman diagnosed with stage IV lung adenocarcinoma harboring an ERBB2 mutation. She received Nivolumab treatment when her disease progresses after previous chemotherapy and Afatinib treatment. However, the patient did not response to Nivolumab. PTEN mutation was detected by next-generation sequencing (NGS) after treatment with Nivolumab. PTEN, a secondary mutation, may be served as a biomarker of resistance to anti-PD-1 immunotherapy in lung adenocarcinoma. The relationship between PTEN mutation and immunotherapy is complex and needs further study.

Multigene Panel Sequencing Reveals Cancer-Specific and Common Somatic Mutations in Colorectal Cancer Patients: An Egyptian Experience

This study aims at identifying common pathogenic somatic mutations at different stages of colorectal carcinogenesis in Egyptian patients. Our cohort included colonoscopic biopsies collected from 120 patients: 20 biopsies from patients with inflammatory bowel disease, 38 from colonic polyp patients, and 62 from patients with colorectal cancer. On top of this, the cohort included 20 biopsies from patients with non-specific mild to moderated colitis. Targeted DNA sequencing using a customized gene panel of 96 colorectal related genes running on the Ion Torrent NGS technology was used to process the samples. Our results revealed that 69% of all cases harbored at least one somatic mutation. Fifty-seven genes were found to carry 232 somatic non-synonymous variants. The most frequently pathogenic somatic mutations were localized in TP53, APC, KRAS, and PIK3CA. In total, 16 somatic mutations were detected in the CRC group and in either the IBD or CP group. In addition, our data showed that 51% of total somatic variants were CRC-specific variants. The average number of CRC-specific variants per sample is 2.4. The top genes carrying CRC-specific mutations are APC, TP53, PIK3CA, FBXW7, ATM, and SMAD4. It seems obvious that TP53 and APC genes were the most affected genes with somatic mutations in all groups. Of interest, 85% and 28% of the APC and TP53 deleterious somatic mutations were located in Exon 14 and Exon 3, respectively. Besides, 37% and 28% of the total somatic mutations identified in APC and TP53 were CRC-specific variants, respectively. Moreover, we identified that, in 29 somatic mutations in 21 genes, their association with CRC patients was unprecedented. Ten detected variants were likely to be novel: six in PIK3CA and four variants in FBXW7. The detected P53, Wnt/βcatenin, Angiogenesis, EGFR, TGF-β and Interleukin signaling pathways were the most altered pathways in 22%, 16%, 12%, 10%, 9% and 9% of the CRC patients, respectively. These results would contribute to a better understanding of the colorectal cancer and in introducing personalized therapies for Egyptian CRC patients.

EGFR and HER2 exon 20 insertions in solid tumours: from biology to treatment

Protein tyrosine kinases of the human epidermal growth factor receptor family, including EGFR and HER2, have emerged as important therapeutic targets in non-small-cell lung, breast and gastroesophageal cancers, and are of relevance for the treatment of various other malignancies (particularly colorectal cancer). Classic activating EGFR exon 19 deletions and exon 21 mutations, and HER2 amplification and/or overexpression, are predictive of response to matched molecularly targeted therapies, translating into favourable objective response rates and survival outcomes. By comparison, cancers with insertion mutations in exon 20 of either EGFR or HER2 are considerably less sensitive to the currently available tyrosine kinase inhibitors and antibodies targeting these receptors. These exon 20 insertions are structurally distinct from other EGFR and HER2 mutations, providing an explanation for this lack of sensitivity. In this Review, we first discuss the prevalence and pan-cancer distribution of EGFR and HER2 exon 20 insertions, their biology and detection, and associated responses to current molecularly targeted therapies and immunotherapies. We then focus on novel approaches that are being developed to more effectively target tumours driven by these non-classic EGFR and HER2 alterations.

An Observational Study to Assess the Molecular Epidemiology and Direct Medical Costs of Epidermal Growth Factor Receptor (EGFR) Mutations in Patients with Advanced EGFR Mutation-Positive Non-Small Cell Lung Cancer Treated with Afatinib in Real-World Clinical Settings in Greece

Purpose

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are the preferred first-line option for patients with advanced, EGFR-mutant non-small cell lung cancer (NSCLC). Afatinib, a second-generation irreversible EGFR-TKI, has been extensively used in Greece in this setting; however, real-world data regarding molecular epidemiology and financial implications of afatinib use are lacking.

Materials and Methods

This was an observational, non-interventional, multicenter, retrospective cohort study, based on real-world data collected from the medical charts/records of patients treated with afatinib between 15/03/2015 and 25/06/2020 and were recorded on a web-based data capture system. Cox models were used to assess the prognostic significance of clinicopathological parameters with respect to clinical outcomes of interest. Cost analysis was conducted from a public third-payer perspective, and only direct medical costs reimbursed by the payer were considered.

Results

A total of 59 patients were treated with afatinib for their EGFR mutation-positive advanced NSCLC; the median age was 61 years (range: 37-91). Performance status was zero in 61%, and brain metastases were present in 13.6%. Forty-four patients (74.6%) had a deletion in exon 19 only, while nine (15.3%) had a mutation in exon 21, 8 of them in L858R and one in L861Q. At a median follow-up of 41.8 months (95% CI 35.9-51.4), the median PFS was 14.3 months (95% CI 12.2-16.4), and the median OS was 29 months (95% CI 25.6-33.4). Corresponding values for patients with deletion 19 only were 14.3 months (95% CI 11.5-18.5) and 28.1 months (95% CI 21.1-32.6), respectively. The mean expenditure for the treatment of each patient equals €25,333.68; with €21,865.06 being attributed to drug acquisition costs, €3325.35 to monitoring costs and €143.27 to adverse event treatment-related costs.

Conclusion

Long-term data in the real-world setting in Greece confirm activity, tolerability and cost-effectiveness of afatinib as first-line treatment of patients with advanced EGFR-mutant NSCLC.

Clinical Trial Registration

Clinicaltrials.gov NCT04640870.

A Real-World, Observational, Prospective Study to Assess the Molecular Epidemiology of Epidermal Growth Factor Receptor (EGFR) Mutations upon Progression on or after First-Line Therapy with a First- or Second-Generation EGFR Tyrosine Kinase Inhibitor in EGFR Mutation-Positive Locally Advanced or Metastatic Non-Small Cell Lung Cancer: The 'LUNGFUL' Study

Simple Summary

Non-small cell lung cancer (NSCLC) accounts for approximately 85% of lung cancer cases, with few patients carrying driver mutations in the gene encoding for epidermal growth factor receptor (EGFR). Advances in translational research have established EGFR tyrosine kinase inhibitors (TKIs) as the standard first-line therapy for NSCLC patients with activating EGFR mutations. The aim of our observational study was to assess the frequency of T790M acquired resistance and predictors of its presence, in patients with EGFR-mutated locally advanced or metastatic NSCLC who have progressed in the first-line EGFR-TKI treatment setting with first- or second-generation TKIs and have undergone molecular testing in tissue and/or plasma biopsy. The study highlights the challenges of performing tissue re-biopsy in routine care settings, which can lead to patients considered non-eligible for certain therapies from which they can benefit, and merits further actions from the healthcare community, in order to establish re-biopsy as a standard procedure.

Abstract

Background: Real-world data on the molecular epidemiology of EGFR resistance mutations at or after progression with first- or second-generation EGFR-TKIs in patients with advanced NSCLC are lacking. Methods: This ongoing observational study was carried out by 23 hospital-based physicians in Greece. The decision to perform cobas^®EGFR Mutation Test v2 in tissue and/or plasma at disease progression was made before enrollment. For patients with negative/inconclusive T790M plasma-based results, tissue re-biopsy could be performed. Results: Ninety-six (96) eligible patients were consecutively enrolled (median age: 67.8 years) between July-2017 and September-2019. Of the patients, 98% were tested upon progression using plasma and 2% using tissue/cytology biopsy. The T790M mutation was detected in 16.0% of liquid biopsies. Tissue re-biopsy was performed in 22.8% of patients with a T790M-negative plasma result. In total, the T790M positivity rate was 21.9%, not differing between patients on first- or second-generation EGFR-TKI. Higher (≥2) ECOG performance status and longer (≥10 months) time to disease progression following EGFR-TKI treatment initiation were associated with T790M positivity. Conclusions: Results from plasma/tissue-cytology samples in a real-world setting, yielded a T790M positivity rate lower than previous reports. Fewer than one in four patients with negative plasma-based testing underwent tissue re-biopsy, indicating the challenges in routine care settings.

PI3K-AKT-mTOR pathway alterations in advanced NSCLC patients after progression on EGFR-TKI and clinical response to EGFR-TKI plus everolimus combination therapy

Background

Several mechanisms including abnormal activation of PI3K-AKT-mTOR pathway have been proved to generate acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC). In this study, we investigated the genomic characteristics of PI3K pathway activated in NSCLC patients after progression on EGFR-TKIs and whether both targeting EGFR and PI3K pathway could overcome resistance.

Methods

A total of 605 NSCLC cases with a history of EGFR TKI treatment were reviewed, in which 324 patients harboring EGFR mutations were confirmed progression on at least one EGFR TKI and finally enrolled. Tumor tissues or blood samples were collected at the onset of TKI progression for next generation sequencing (NGS). Six EGFR mutant patients with co-occurring mutations in PI3K pathway were retrospectively collected to assess the effect of EGFR TKI plus everolimus, a mTOR inhibitor.

Results

Forty-nine (14.9%) patients resistant to EGFR TKIs have at least one genetic variation in PI3K pathway. PIK3CA, PTEN and AKT1 variations were detected in 31 (9.5%), 18 (5.5%) and 3 (0.9%) of patients, respectively. No significant differences were observed in distribution of PI3K pathway alterations among patients with different EGFR mutations (EGFR exon19 deletion mutations/EGFR L858R/uncommon EGFR mutations) and among patients resistant to different EGFR TKIs. For patients treated with everolimus and EGFR-TKI, five (5/6, 83.3%) achieved stable disease (SD) and one (1/6, 16.7%) didn’t receive disease control. The median progression-free survival (PFS) was 2.1 months (95% confidence interval, 1.35–4.3 months, range, 0.9–4.4 months). The most common adverse events were dental ulcer (6/6), rash (1/6).

Conclusions

Our study revealed that PI3K pathway was activated in at least 14.9% in EGFR-TKI resistant patients. EGFR-TKIs plus everolimus showed limited antitumor activity in EGFR mutant NSCLC patients with PI3K pathway aberrations.

Resistance to Both Chemotherapy and EGFR-TKI in Small Cell Lung Cancer With EGFR 19-Del Mutation: A Case Report

Epidermal growth factor receptor (EGFR) mutations are common in non-small cell lung cancers, but rare in small cell lung cancers (SCLCs). In previous reports, some SCLC patients with EGFR mutations could benefit from EGFR tyrosine kinase inhibitors (TKIs). In this study, we reported a case in which an SCLC patient with EGFR exon 19 deletion (19-Del) mutation did not benefit from EGFR-TKIs. Interestingly, the standard treatment strategies for SCLC also failed to control tumor progression. Moreover, we screened 43 SCLC patients in China and found that the frequency of EGFR mutations in Chinese SCLC patients was about 4.65% by next-generation sequencing (NGS). Collectively, this case illustrated a rare subtype of SCLCs which harbored EGFR mutations and was intrinsically resistant to standard treatments and EGFR-TKIs. We also tried to explore the mechanisms underlying drug resistance. The literature concerning SCLCs with EGFR mutations is reviewed.

Mutation Profile of Resected EGFR-Mutated Lung Adenocarcinoma by Next-Generation Sequencing

BACKGROUND

The efficacy of adjuvant targeted therapy for operable lung cancer is still under debate. Comprehensive genetic profiling is needed for detecting co-mutations in resected epidermal growth factor receptor (EGFR)-mutated lung adenocarcinoma (ADC), which may interfere the efficacy of adjuvant tyrosine kinase inhibitor (TKI) treatment.

MATERIALS AND METHODS

Mutation profiling of 416 cancer-relevant genes was conducted for 139 resected stage I-IIIa lung ADCs with EGFR mutations using targeted next-generation sequencing. Co-mutation profiles were systematically analyzed.

RESULTS

Rare EGFR alterations other than exon 19 deletion and L858R, such as L861Q (∼3%) and G719A (∼2%), were identified at low frequencies. Approximately 10% of patients had mutations in EGFR exon 20 that could confer resistance to first-generation TKIs. Ninety-one percent of patients harbored at least one co-mutation in addition to the major EGFR mutation. TP53 was the top mutated gene and was found more frequently mutated at later stage. Markedly, NF1 mutations were found only in stage II-III ADCs. Conversely, RB1 mutations were more frequent in stage I ADCs, whereas APC mutations were observed exclusively in this group. Thirty-four percent of patients with EGFR TKI-sensitizing mutations had genetic alterations involving EGFR downstream effectors or bypass pathways that could affect the response to EGFR TKIs, such as PIK3CA, BRCA1, and NOTCH1.

CONCLUSION

Operable lung ADCs with EGFR TKI-sensitizing mutations are associated with a high proportion of co-mutations. Mutation profiling of these resected tumors could facilitate in determining the applicability and efficacy of adjuvant EGFR TKI therapeutic strategy.

IMPLICATIONS FOR PRACTICE

The efficacy of adjuvant epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) therapy for lung cancer harboring EGFR mutation after surgical resection is still under debate. Next-generation sequencing of 416 cancer-relevant genes in 139 resected lung cancers revealed the co-mutational landscape with background EGFR mutation. Notably, the study identified potential EGFR TKI-resistant mutations in 34.71% of patients with a drug-sensitizing EGFR mutation and who were naive in terms of targeted therapy. A comprehensive mutation profiling of these resected tumors could facilitate in determining the applicability and efficacy of adjuvant EGFR TKI therapeutic strategy for these patients.

CT texture analysis as predictive factor in metastatic lung adenocarcinoma treated with tyrosine kinase inhibitors (TKIs)

PURPOSE

To assess the predictive and prognostic value of pre-treatment CT texture features in lung adenocarcinoma treated with tyrosine kinase inhibitors (TKI).

MATERIALS AND METHODS

Texture analysis was performed using commercially available software (TexRAD Ltd, Cambridge, UK) on pre-treatment contrast-enhanced CT studies from 50 patients with metastatic lung adenocarcinoma treated by TKI. Texture features were quantified on a 5-mm-thick central slice of the primary tumor and were correlated with progression-free and overall survival (PFS and OS) using an internally cross-validated machine learning approach then validated on a bootstrapped sample.

RESULTS

Median PFS and OS were 10.5 and 20.7 months, respectively. A noninvasive signature based on five texture parameters predicted 6-month progression with Area Under the Curve (AUC) of 0.8 (95% CI) and 1-year progression with AUC of 0.76. A high-risk group had hazard ratios for progression of 4.63 and 5.78 when divided by median and best cut-off points, respectively. Texture signature did not correlate with OS. Available clinical variables did not correlate with PFS or with OS.

CONCLUSION

Texture features seem to be associated with PFS in lung adenocarcinoma treated with TKI.

Chromosome 7 Multiplication in EGFR-positive Lung Carcinomas Based on Tissue Microarray Analysis

BACKGROUND/AIM

Epidermal growth factor receptor (EGFR) over-activation is observed in significant proportions of non-small cell lung carcinomas (NSCLC). Our aim was to investigate the role of chromosome 7 multiplication with regard to its influence in EGFR expression, combined or not with gene amplification.

MATERIALS AND METHODS

Using tissue microarray technology, fifty (n=50) primary NSCLCs were cored and re-embedded into the final recipient block. Immunohistochemistry (IHC) and also chromogenic in situ hybridization (CISH) were performed.

RESULTS

EGFR expression at any level was detected in 40/50 (80%) cores. Over-expression was observed in 23/40 (57.5%) cases. Gene amplification was identified in 11/50 (22%) cases whereas chromosome 7 polysomy in 8/50 (16%) cases. Pure chromosome 7 multiplication alone led to low or moderate levels of expression. Overall EGFR expression was correlated with gene (p=0.001) and interestingly with chromosome 7 centromere numerical imbalances (p=0.004).

CONCLUSION

EGFR expression is associated not only with amplification, but also with chromosome 7 centromere multiple copies. Chromosome 7 multiplication -due to centromere region amplification or true polysomy- is critical for applying monoclonal antibody targeted therapeutic strategies excluding the pure non-amplified cases.

Molecular Screening of Small Biopsy Samples Using Next-Generation Sequencing in Korean Patients with Advanced Non-small Cell Lung Cancer: Korean Lung Cancer Consortium (KLCC-13-01)

Background

Non-small cell lung cancer (NSCLC) is a common type of cancer with poor prognosis. As individual cancers exhibit unique mutation patterns, identifying and characterizing gene mutations in NSCLC might help predict patient outcomes and guide treatment. The aim of this study was to evaluate the clinical adequacy of molecular testing using next-generation sequencing (NGS) for small biopsy samples and characterize the mutational landscape of Korean patients with advanced NSCLC.

Methods

DNA was extracted from small biopsy samples of 162 patients with advanced NSCLC. Targeted NGS of genomic alterations was conducted using Ion AmpliSeq Cancer Hotspot Panel v2.

Results

The median age of patients was 64 years (range, 32 to 83 years) and the majority had stage IV NSCLC at the time of cancer diagnosis (90%). Among the 162 patients, 161 patients (99.4%) had novel or hotspot mutations (range, 1 to 21 mutated genes). Mutations were found in 41 genes. Three of the most frequently mutated genes were TP53 (151, 93.2%), KDR (104, 64.2%), and epidermal growth factor receptor (EGFR; 69, 42.6%). We also observed coexistence of EGFR and other oncogene (such as KRAS, PIC3CA, PTEN, and STK11) mutations. Given that 69.6% (48/69) of EGFR mutant patients were treated with EGFR tyrosine kinase inhibitors, EGFR mutant status had higher prognostic ability in this study.

Conclusions

These results suggest that targeted NGS using small biopsy samples is feasible and allows for the detection of both common and rare mutations in NSCLC.

Quantification of mutant alleles in circulating tumor DNA can predict survival in lung cancer

Purpose

We aimed to investigate the feasibility of droplet digital PCR (ddPCR) for the quantitative and dynamic detection of EGFR mutations and next generation sequencing (NGS) for screening EGFR-tyrosine kinase inhibitors (EGFR-TKIs) resistance-relevant mutations in circulating tumor DNA (ctDNA) from advanced lung adenocarcinoma (ADC) patients.

Results

Detection limit of EGFR mutation in ctDNA by ddPCR was 0.04%. Taking the EGFR mutation in tumor tissue as the golden standard, the concordance of EGFR mutations detected in ctDNA was 74% (54/73). Patients with EGFR mutation in ctDNA (n = 54) superior progression-free survival (PFS, median, 12.6 vs. 6.7 months, P < 0.001) and overall survival (OS, median, 35.6 vs. 23.8 months, P = 0.028) compared to those with EGFR wild type in ctDNA (n = 19). Patients with high EGFR-mutated abundance in ctDNA (> 5.15%) showed better PFS compared to those with low EGFR mutated abundance (≤ 5.15%) (PFS, median, 15.4 vs. 11.1 months, P = 0.021). NGS results showed that 66.6% (8/12) total mutational copy number were elevated and 76.5% (26/34) mutual mutation frequency increased after disease progression.

Methods

Seventy-three advanced ADC patients with tumor tissues carrying EGFR mutations and their matched pre- and post-EGFR-TKIs plasma samples were enrolled in this study. Absolute quantities of plasma EGFR mutant and wild-type alleles were measured by ddPCR. Multi-genes testing was performed using NGS in 12 patients.

Conclusions

Dynamic and quantitative analysis of EGFR mutation in ctDNA could guide personalized therapy for advanced ADC. NGS shows good performance in multiple genes testing especially novel and uncommon genes.

Clinical Characteristics and Survival Outcomes for Non-Small-Cell Lung Cancer Patients with Epidermal Growth Factor Receptor Double Mutations

Multiple randomized clinical trials have demonstrated that epidermal growth factor receptor (EGFR) exon 19 deletion (19Del) and exon 21 L858R mutation (L858R) are highly correlated with sensitivity to epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) treatment in non-small-cell lung cancer (NSCLC). A mutation in exon 20 (T790M) is reportedly associated with resistance to EGFR-TKIs. However, few studies have focused on patients harboring double mutations in these 3 mutation sites. In this retrospective study, forty-five patients (45/2546, 1.7%) harbored double mutations of 19Del, L858R, and T790M. Twenty-four patients with EGFR double mutations received EGFR-TKI therapy. Clinical characteristics of these patients, including the response to EGFR-TKIs and progression-free survival outcome for EGFR-TKI treatment (PFS-TKI), were analyzed. Patients with EGFR double mutations were more likely to be nonsmokers, have an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0-1, have adenocarcinoma, and be at stage III-IV. The ORR, DCR, and median PFS-TKI in patients harboring EGFR double mutations were lower than in patients with a single EGFR-activating mutation. The differences in ORR and DCR were statistically insignificant between the 3 groups. Patients with double mutations of 19Del and T790M had longer PFS-TKIs than patients in the other 2 groups.

Targeted sequencing identifies genetic alterations that confer primary resistance to EGFR tyrosine kinase inhibitor (Korean Lung Cancer Consortium)

Background

Non-small-cell lung cancer (NSCLC) patients with activating epidermal growth factor receptor (EGFR) mutations may exhibit primary resistance to EGFR tyrosine kinase inhibitor (TKI). We aimed to examine genomic alterations associated with de novo resistance to gefitinib in a prospective study of NSCLC patients.

Methods

One-hundred and fifty two patients with activating EGFR mutations were included in this study and 136 patients' tumor sample were available for targeted sequencing of genomic alterations in 22 genes using the Colon and Lung Cancer panel (Ampliseq, Life Technologies).

Results

All 132 patients with EGFR mutation were treated with gefitinib for their treatment of advanced NSCLC. Twenty patients showed primary resistance to EGFR TKI, and were classified as non-responders. A total of 543 somatic single-nucleotide variants (498 missense, 13 nonsense) and 32 frameshift insertions/deletions, with a median of 3 mutations per sample. TP53 was most commonly mutated (47%) and mutations in SMAD4 was also common (19%), as well as DDR2 (16%), PIK3CA (15%), STK11 (14%), and BRAF (7%). Genomic mutations in the PI3K/Akt/mTOR pathway were commonly found in non-responders (45%) compared to responders (27%), and they had significantly shorter progression-free survival and overall survival compared to patients without mutations (2.1 vs. 12.8 months, P=0.04, 15.7 vs. not reached, P<0.001). FGFR 1-3 alterations, KRAS mutations and TP53 mutations were more commonly detected in non-responders compared to responders.

Conclusion

Genomic mutations in the PI3K/Akt/mTOR pathway were commonly identified in non-responders and may confer resistance to EGFR TKI. Screening lung adenocarcinoma patients with clinical cancer gene test may aid in selecting out those who show primary resistance to EGFR TKI (NCT01697163).

Erlotinib Salvage Therapy in Pulmonary Adenocarcinoma Patients With Disease Progression After Previous EGFR-TKI Treatment

BACKGROUND

Erlotinib is an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) with promising efficacy in treating pulmonary adenocarcinoma. Treatment choices are few when patients with pulmonary adenocarcinoma have failed both EGFR-TKI and chemotherapy. The purpose of this study was to demonstrate the efficacy of erlotinib as salvage treatment for these nonresponsive patients.

METHODS

We retrospectively reviewed the chart records of our stage IV pulmonary adenocarcinoma patients who were diagnosed and treated between July 2004 and June 2013. Clinical data, including type of response to treatment, time to disease progression, duration between the end of first-line EGFR-TKI treatment and starting erlotinib treatment, and overall survival time, were collected.

RESULTS

A total of 98 patients were enrolled, and all had been treated with EGFR-TKI, either as a first-line therapy or following platinum-based chemotherapy; of them, 60 patients had a response to initial EGFR-TKI treatment. All received erlotinib as salvage treatment after their disease had progressed following EGFR-TKI treatment. Ninety-three (93.3%) patients had also received previous platinum-based chemotherapy. The median progression-free survival with erlotinib as salvage treatment for patients with and without a response to front-line EGFR-TKI was 4.9 and 3.4 months (P=0.869), respectively. The progression-free survival with erlotinib treatment in the sensitizing EGFR mutation group was 4.3 months, and in the EGFR wild-type group it was 2.6 months (P=0.22).

CONCLUSIONS

In pulmonary adenocarcinoma patients who had been heavily treated, erlotinib could still be a choice, regardless of the EGFR mutation status, or whether the patients had responded to previous EGFR-TKI treatment.

The Molecular Pathology of Lung Cancer

Advances in lung cancer genomics have revolutionized the diagnosis and treatment of this heterogeneous and clinically significant group of tumors. This article provides a broad overview of the most clinically relevant oncogenic alterations in common and rare lung tumors, with an emphasis on the pathologic correlates of the major oncogenic drivers, including EGFR, KRAS, ALK, and MET. Illustrations emphasize the morphologic diversity of lung adenocarcinoma, including genotype-phenotype correlations of genomic evolution in tumorigenesis. Molecular diagnostic approaches, including PCR-based testing, massively parallel sequencing, fluorescence in situ hybridization, and immunohistochemistry are reviewed.

Detection of activating and acquired resistant mutation in plasma from EGFR-mutated NSCLC patients by peptide nucleic acid (PNA) clamping-assisted fluorescence melting curve analysis

This study was designed to prospectively examine whether peptide nucleic acid clamping-assisted fluorescence melting curve analysis (PANAMutyper™) is feasible for the detection of activating and acquired resistant epidermal growth factor receptor (EGFR) mutation in plasma. Patients with non-small cell lung cancer harboring activating EGFR mutations who were scheduled to undergo EGFR-tyrosine kinase inhibitors (EGFR-TKIs) were enrolled between September 2011 and March 2015. A total of 102 patients with EGFR-mutated lung cancer were enrolled, 53 had available plasma samples at disease progression, and 28 underwent serial plasma sampling during EGFR-TKI treatment. EGFR-TKI-sensitizing and T790M mutations were detected in the plasma of 68.6% (70/102) at baseline and 30.2% (16/53) at disease progression, respectively. The concordance rates for matched tissue and plasma samples were 80.4% and 90.2% for E19del and L858R mutations at baseline and 56.3% for T790M mutation at disease progression. The sustained presence of plasma EGFR mutations four weeks after EGFR-TKI predicted a poor objective response rate (30.0% vs. 87.5%, P = 0.025), as well as worse progression-free survival (hazard ratio [HR], 4.381) and overall survival (HR, 5.475). Longitudinal analysis could detect T790M mutations earlier than disease progression based on imaging study (median time from appearance of T790M in plasma samples to progression at imaging scan, 103 days). In conclusion, PANAMutyper™ is reliable for detecting activating and acquired resistant EGFR mutation in plasma, and predicts responses to EGFR-TKI via longitudinal monitoring of EGFR mutation during treatment.

The impact of heterogeneity in phosphoinositide 3-kinase pathway in human cancer and possible therapeutic treatments

Phosphatidylinositol 3-kinase catalytic subunit alpha (PIK3CA) plays a crucial role in the initiation and progress of cancerous tumors through the overexpression of the PI3K pathway promoting uncontrollable levels of cell proliferation. In addition only Class I PI3K has been discovered to be involved in human cancer due to its unique ability to produce phosphoinositide 3,4,5 trisphosphate (PIP3), which has been discovered to play a crucial role in human oncogenesis. The role of PIK3CA is lucubrated in breast cancer and gastric cancer, but is not well characterized in lung diseases. In this review, we summarized the common biology and mutations in PIK3CA with its related signaling pathways. Furthermore, we elucidated the PIK3CA heterogeneity in different domains, between various cancers and in different lung cancers. We also take a look at current inhibitors such as KP-372-1 (KP-1), KP-372-2 (KP-2), GSK690693, etc. in order to highlight potential treatment of PIK3CA mutations in human cancer and what directions future research should focus on.

EGFR mutations in non-small cell lung cancer: an audit from West China Hospital

OBJECTIVES

To discover the incidence and characteristics of EGFR mutations in non-small cell lung cancer (NSCLC) in a single, large cohort as a part of routine diagnostic investigations.

METHODS

We reviewed EGFR mutations investigated by Amplification Refractory Mutation System (ARMS) PCR (covering 29 known mutations) using DNA samples from FFPE tissue or cell clot specimens in a total of 3894 cases of NSCLC analysed between 2012-2014.

RESULTS

EGFR mutations are preferentially associated with adenocarcinomaand adenosquamous histology, particularly those well to moderately differentiated, and were significantly more common in female than male patients irrespective of histological subtypes. Exon 19 deletion (45.7%) and exon 21 L858R (45.6%) accounted for the vast majority of the EGFR mutations detected, with the remaining mutations being infrequent (<2%). Compound mutations were seen in 51 (3%) of the mutant cases, the combination of these compound mutations could be classified into three subgroups according to the potential impact of individual mutations on EGFR TKI therapy. Accordingly, 7 cases had both sensitive mutations, 4 cases harboured one sensitive and one less responsive /uncertain mutation, 19 cases contained one sensitive and one resistant change, and a further 21 cases had two less responsive /uncertain mutations.

CONCLUSION

Our data represents the largest EGFR mutation survey based on routine clinical diagnostic laboratory data from a single institution, it confirms the incidence and characteristics of EGFR mutations in NSCLC seen in Asian patients, and also unravels the combinatorial nature of rare compound EGFR mutations.

EGFR gene deregulation mechanisms in lung adenocarcinoma: A molecular review

For the last two decades, evolution in molecular biology has expanded our knowledge in decoding a broad spectrum of genomic imbalances that progressively lead normal cells to a neoplastic state and finally to complete malignant transformation. Concerning oncogenes and signaling transduction pathways mediated by them, identification of specific gene alterations remains a critical process for handling patients by applying targeted therapeutic regimens. The epidermal growth factor receptor (EGFR) signaling pathway plays a crucial role in regulating cell proliferation, differentiation and apoptosis in normal cells. EGFR mutations and amplification represent the gene's main deregulation mechanisms in cancers of different histo-genetic origin. Furthermore, intra-cancer molecular heterogeneity due to clonal rise and expansion mainly explains the variable resistance to novel anti-EGFR monoclonal antibody (mAb), and also tyrosine kinase inhibitors (TKIs). According to recently published 2015 WHO new classification, lung cancer is the leading cause of death related to cancer and its incidence is still on the increase worldwide. The majority of patients suffering from lung cancer are diagnosed with epithelial tumors (adenocarcinoma predominantly and squamous cell carcinoma represent ∼85% of all pathologically defined lung cancer cases). In those patients, EGFR-activating somatic mutations in exons 18/19/20/21 modify patients' sensitivity (i.e. exon 21 L858R, exon 19 LREA deletion) or resistance (ie exon 20 T790M and/or insertion) to TKI mediated targeted therapeutic strategies. Additionally, the role of specific micro-RNAs that affect EGFR regulation is under investigation. In the current review, we focused on EGFR gene/protein structural and functional aspects and the corresponding alterations that occur mainly in lung adenocarcinoma to critically modify its molecular landscape.

A sensitive and practical method to detect the T790M mutation in the epidermal growth factor receptor

The current study aimed to develop a method to rapidly, sensitively and practically screen for the epidermal growth factor receptor (EGFR) T790M mutation. This method combines an allele-specific competitive blocker (ACB) with a TaqMan quantitative polymerase chain reaction (PCR) amplification refractory mutation system (ARMS) in a one-step reaction. Using a mimic of a human genomic DNA panel containing serially diluted mutant alleles, the performance efficacy of this method was assessed. Using this method, the EGFR T790M mutation was detected in tyrosine kinase inhibitor (TKI)-naïve samples obtained from 27 non-small cell lung cancer (NSCLC) patients with EGFR-activating mutations. The association between de novo T790M mutations and the clinical benefit of EGFR-TKI treatment was also analysed. The sensitivity of this method was as low as 0.01%. In the samples from the 27 NSCLC patients, this method identified 6 mutant patients (22.2%), which was higher than the detection rate with scorpion ARMS (0.0%). No clinical variables were associated with the occurrence of a de novo T790M mutation. The median progression-free survival time in the TKI-naïve patients with a T790M mutation was shorter that that of patients without the mutation, but the difference was not significant (3.2 vs. 19.5 months, respectively; P=0.256). The median overall survival time in the groups with or without T790M mutation also did not significantly differ (10 vs. 20 months, respectively; P=0.689). Overall, the ACB-ARMS PCR method could be useful for detecting the EGFR T790M mutation in clinical samples that contain only a small number of mutant alleles. The clinical significance of a de novo T790M mutation should be further investigated.

Chronic Obstructive Pulmonary Disease-Related Non-Small-Cell Lung Cancer Exhibits a Low Prevalence of EGFR and ALK Driver Mutations

Lung cancer and chronic obstructive pulmonary disease (COPD) are two major lung diseases. Epidermal growth factor receptor (EGFR) mutations, v-Ki-ras2 Kirsten rat sarcoma (KRAS) mutations and anaplastic lymphoma kinase (ALK) gene rearrangements represent driver mutations that are frequently assessed on initial evaluation of non-small-cell lung cancer (NSCLC). The present study focused on the expression of driver mutations in NSCLC patients presenting with COPD and further evaluated the association between NSCLC and COPD. Data from 501 consecutive patients with histologically proven recurrent or metastatic NSCLC were analyzed retrospectively. The patients underwent spirometry and genotyping of EGFR, ALK, and KRAS in tissue samples. Patient characteristics and expression of driver mutations were compared between the COPD and non-COPD groups. Among 350 patients with spirometric results, 106 (30.3%) were diagnosed with COPD, 108 (30.9%) had EGFR mutations, 31 (8.9%) had KRAS mutations, and 34 (9.7%) showed ALK rearrangements. COPD was independently associated with lower prevalences of EGFR mutations (95% confidence interval [CI], 0.254-0.931, p = 0.029) and ALK rearrangements (95% CI, 0.065-0.600, p = 0.004). The proportions of EGFR mutations and ALK rearrangements decreased as the severity of airflow obstruction increased (p = 0.001). In never smokers, the prevalence of EGFR mutations was significantly lower in the COPD group than in the non-COPD group (12.7% vs. 49.0%, p = 0.002). COPD-related NSCLC patients exhibited low prevalences of EGFR mutations and ALK rearrangements compared with the non-COPD group. Further studies are required regarding the molecular mechanisms underlying lung cancer associated with COPD.

Construction and analysis of three networks of genes and microRNAs in adenocarcinoma

Adenocarcinoma is one of the most serious diseases that threaten human health. Numerous studies have investigated adenocarcinoma and have obtained a considerable amount of data regarding genes and microRNA (miRNA) in adenocarcinoma. However, studies have only focused on one or a small number of genes and miRNAs, and the data is stored in a scattered form, making it challenging to summarize and assess the associations between the genes and miRNAs. In the present study, three networks of genes and miRNAs in adenocarcinoma were focused on. This enabled the construction of networks of elements involved in adenocarcinoma and the analysis of these networks, rather than only discussing one gene. Transcription factors (TFs), miRNAs, and target and host genes of miRNAs in adenocarcinoma, and the regulatory associations between these elements were identified in the present study. These elements and associations were then used to construct three networks, which consisted of the differentially-expressed, associated and global networks. The similarities and differences between the three networks were compared and analyzed. In total, 3 notable TFs, consisting of TP53, phosphatase and tensin homolog and SMAD4, were identified in adenocarcinoma. These TFs were able to regulate the differentially-expressed genes and the majority of the differentially-expressed miRNAs. Certain important regulatory associations were also found in adenocarcinoma, in addition to self-regulating associations between TFs and miRNAs. The upstream and downstream elements of the differentially-expressed genes and miRNAs were recorded, which revealed the regulatory associations between genes and miRNAs. The present study clearly revealed components of the pathogenesis of adenocarcinoma and the regulatory associations between the elements in adenocarcinoma. The present study may aid the investigation of gene therapy in adenocarcinoma and provides a theoretical basis for studies of gene therapy methods as a treatment for adenocarcinoma.

Predictive value of K-ras and PIK3CA in non-small cell lung cancer patients treated with EGFR-TKIs: a systemic review and meta-analysis

Objective

A meta-analysis was performed to augment the insufficient data on the impact of mutative EGFR downstream phosphatidylinositol-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways on the clinical efficiency of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) treatment of non-small cell lung cancer (NSCLC) patients.

Methods

Network databases were explored in April, 2015. Papers that investigated the clinical outcomes of NSCLC patients treated with EGFR-TKIs according to the status of K-ras and/or PIK3CA gene mutation were included. A quantitative meta-analysis was conducted using standard statistical methods. Odds ratios (ORs) for objective response rate (ORR) and hazard ratios (HRs) for progression-free survival (PFS) and overall survival (OS) were calculated.

Results

Mutation in K-ras significantly predicted poor ORR [OR =0.22; 95% confidence interval (CI), 0.13-0.35], shorter PFS (HR =1.56; 95% CI, 1.27-1.92), and shorter OS (HR =1.59; 95% CI, 1.33-1.91) in NSCLC patients treated with EGFR-TKIs. Mutant PIK3CA significantly predicted shorter OS (HR =1.83; 95% CI, 1.05-3.20), showed poor ORR (OR =0.70; 95% CI, 0.22-2.18), and shorter PFS (HR =1.79; 95% CI, 0.91-3.53) in NSCLC patients treated with EGFR-TKIs.

Conclusion

K-ras mutation adversely affected the clinical response and survival of NSCLC patients treated with EGFR-TKIs. PIK3CA mutation showed similar trends. In addition to EGFR, adding K-ras and PIK3CA as routine gene biomarkers in clinical genetic analysis is valuable to optimize the effectiveness of EGFR-TKI regimens and identify optimal patients who will benefit from EGFR-TKI treatment.

Comparison of uncommon EGFR exon 21 L858R compound mutations with single mutation

Non-small-cell lung cancer with epidermal growth factor receptor (EGFR) mutation is sensitive to EGFR tyrosine kinase inhibitors (TKIs). But little is known about the response to EGFR TKIs and the prognostic role of compound mutations. This study compared the uncommon EGFR exon 21 L858R compound mutations with single mutation to characterize EGFR compound mutations and investigated their response to EGFR TKI treatment. We retrospectively screened 799 non-small-cell lung cancer patients from August 1, 2009 to June 1, 2012 by EGFR mutation testing. EGFR mutations were detected in 443 patients, with 22 (4.97%) compound mutations. Subsequently, six patients with EGFR exon 21 L858R compound mutations and 18 paired patients with single L858R mutation were well characterized. Finally, we also analyzed the EGFR TKI treatment response and patients’ outcomes of compound or single L858R mutations. There was no differential treatment effect on the disease control rate and objective response rate between the L858R compound mutations and single mutation groups. No significant difference in overall survival or progression-free survival of these two groups was found by log-rank test. In conclusion, we demonstrated that no significant difference was detected in the response to EGFR TKIs and patients’ outcomes in the compound and single mutation groups.

Multiple resistant factors in lung cancer with primary resistance to EGFR-TK inhibitors confer poor survival

OBJECTIVES

EGFR activating mutations have been recognized as the most important predictor of response to EGFR-tyrosine kinase inhibitors (EGFR-TKIs). However, 20-30% of patients harboring EGFR activating mutations show a poor response requiring investigation for underlying mechanisms.

MATERIALS AND METHODS

Characteristics of 541 patients with lung cancer harboring EGFR activating mutations were analyzed to determine contributing factors that could differentiate responders and non-responders. In addition, previously suggested moleculo-pathologic factors of resistance such as IκB, IGF1R, PTEN, MET, AXL and BIM were evaluated in patients exhibiting primary resistance who had sufficient biopsied tissues available for analyses.

RESULTS

Responders to EGFR-TKIs had a higher incidence of deletion mutations and more frequent presence of EGFR amplifications than non-responders. The median OS was 21 months (95% CI 26.1-30.4) in responders compared to 8 months (95% CI 8.7-15.8) in non-responders (p<0.001). In analyses of patients with primary resistance, we found that 27.3% (6/22) of them exhibited decreased expression of IκB, and 9.1% (2/22) of patients showed increased expression of IGF1R. Loss of PTEN was noted in 54.5%, and BIM polymorphism was found in 19% of patients. No patients had MET amplification, while expression of AXL was detected in 5 patients. Two patients had simultaneous T790M EGFR or PIK3CA mutation alongside EGFR activating mutation. Most of patients exhibited multiple abnormalities of these factors. The overall survival was worse in the group with multiple resistant factors.

CONCLUSION

Our study suggests that mechanisms of primary resistance may be more complex than those underlying acquired resistance, with several factors concomitantly contributing to primary resistance.

Correlation of EGFR expression, gene copy number and clinicopathological status in NSCLC

BACKGROUND

Epidermal Growth Factor Receptor (EGFR) targeting therapies are currently of great relevance for the treatment of lung cancer. For this reason, in addition to mutational analysis immunohistochemistry (IHC) of EGFR in lung cancer has been discussed for the decision making of according therapeutic strategies. The aim of this study was to obtain standardization of EGFR-expression methods for the selection of patients who might benefit of EGFR targeting therapies.

METHODS

As a starting point of a broad investigation, aimed at elucidating the expression of EGFR on different biological levels, four EGFR specific antibodies were analyzed concerning potential differences in expression levels by Immunohistochemistry (IHC) and correlated with fluorescence in situ hybridization (FISH) analysis and clinicopathological data. 206 tumor tissues were analyzed in a tissue microarray format employing immunohistochemistry with four different antibodies including Dako PharmDx kit (clone 2-18C9), clone 31G7, clone 2.1E1 and clone SP84 using three different scoring methods. Protein expression was compared to FISH utilizing two different probes.

RESULTS

EGFR protein expression determined by IHC with Dako PharmDx kit, clone 31G7 and clone 2.1E1 (p ≤ 0.05) correlated significantly with both FISH probes independently of the three scoring methods; best correlation is shown for 31G7 using the scoring method that defined EGFR positivity when ≥ 10% of the tumor cells show membranous staining of moderate and severe intensity (p=0.001).

CONCLUSION

Overall, our data show differences in EGFR expression determined by IHC, due to the applied antibody. Highest concordance with FISH is shown for antibody clone 31G7, evaluated with score B (p=0.001). On this account, this antibody clone might by utilized for standard evaluation of EGFR expression by IHC.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_165.

Efficacy analysis of tyrosine kinase inhibitors on rare non-small cell lung cancer patients harboring complex EGFR mutations

The efficacy of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI) in patients with non-small cell lung cancer (NSCLC) is related to EGFR mutations. Although the p.L858R point mutation in exon 21 and the in-frame deletion mutation in exon 19 are well known, efficacy of EGFR-TKI in patients with more than one EGFR mutation is not well understood. 799 NSCLC patients were screened for EGFR mutations. Of the 799 patients, 443 (55.4%) had mutations, out of which 22 (2.75%) had multiple complex mutations. Most multiple mutations (20/22) harbored common mutations such as the p.L858R point mutation in exon 21 and the in-frame deletion mutation in exon 19. 11 out of 22 patients who had multiple EGFR mutations underwent TKI therapy and primary end-points of progression free and overall survival were determined. Our analysis revealed that cases with multiple mutations had similar end-point outcomes as single mutation to TKI therapy. Report of these cases will be helpful in decision making for treatment of NSCLC patients harboring multiple EGFR mutations.

EGFR CA repeat polymorphism predict clinical outcome in EGFR mutation positive NSCLC patients treated with erlotinib

OBJECTIVES

Somatic mutations in the epidermal growth factor receptor (EGFR) are predictors of efficacy for treatment with the EGFR tyrosine kinase inhibitor erlotinib in non-small cell lung cancer (NSCLC). A CA repeat polymorphism in intron 1 of the EGFR gene influences the transcription of the EGFR gene. This study evaluates the association between the CA repeat polymorphism and outcome in NSCLC patients treated with erlotinib.

MATERIALS AND METHODS

Number of CA repeats in the EGFR gene was evaluated with PCR-fragment length analysis by capillary electrophoresis in 432 advanced NSCLC patients treated with erlotinib irrespective of EGFR mutation status. Patients were dichotomized into harboring short allele (CA≤16 in any allele) or long alleles (CA>16 in both alleles). Number of repeats was correlated with clinical characteristic and outcome. A subgroup analysis was performed based on the somatic EGFR mutation status.

RESULTS

In EGFR mutation positive patients (N=62) we demonstrate a significantly higher median progression free survival (HR=0.39 (0.22-0.70); p=0.002) and overall survival (HR=0.43 (0.23-0.78); p=0.006) in patients also harboring a short CA repeat length vs. a long (median follow-up time of 52.2 months). The result remained highly significant in a multivariate Cox proportional hazards model. This correlation was not seen in EGFR mutation negative patients.

CONCLUSION

Our study demonstrate that in EGFR mutation positive NSCLC patients treated with erlotinib a low number of CA repeats in intron 1 of the EGFR gene is a predictor for both longer progression free survival and overall survival.