Characterization of common and rare mutations in EGFR and associated clinicopathological features in a large population of Chinese patients with lung cancer

Spectrum of EGFR aberrations and potential clinical implications: insights from integrative pan-cancer analysis

Background

Human epidermal growth factor receptor (EGFR) is an oncogenic gene and one of top targets of precision therapy in lung cancer with EGFR mutations. Although there are many reports for some individual cancers, comprehensive profiling of EGFR mutations, overexpression, amplification, DNA methylation, and their clinical associations across many different cancers simultaneously was not available. This study aimed to fill the gap and provide insights to the alteration spectrum of EGFR and its therapeutic and prognostic implications.

Methods

The Cancer Genome Atlas (TCGA) datasets for 32 cancer types involving 11,314 patients were analyzed for alterations (mutations and amplification/deletion), abnormal expression and DNA methylation in EGFR gene. Mutation frequency, genomic location distribution, functional impact, and clinical targeted therapy implication were compared among different cancer types, and their associations with patient survival were analyzed.

Results

EGFR alteration frequency, mutation sites across functional domains, amplification, overexpression, and DNA methylation patterns differed greatly among different cancer types. The overall mutation frequency in all cancers combined was relatively low. Targetable mutations, mainly in lung cancer, were primarily found in the Pkinase_Tyr domain. Glioblastoma multiforme had the highest rate of alterations, but it was dominated by gene amplification and most mutations were in the Furin‐like domain where targeted therapy was less effective. Low‐grade glioma often had gene amplification and increased EGFR expression which was associated with poor outcome. Colon and pancreatic adenocarcinoma had very few EGFR mutations; however, high EGFR expression was significantly associated with short patient survival. Squamous cell carcinoma regardless of their sites (the head and neck, lung, or esophagus) exhibited similar characteristics with an alteration frequency of about 5.0%, was dominated by gene amplification, and had increased EGFR expression generally associated with short patient survival. DNA methylation was highly associated with EGFR expression and patient outcomes in some cancers.

Conclusions

EGFR aberration type, frequency, distribution in functional domains, and expression vary from cancer to cancer. While mutations in the Pkinase_Tyr domain are more important for treatment selection, increased expression from amplification or deregulation affects more tumor types and leads to worse outcome, which calls for new treatment strategies for these EGFR‐driven tumors.

Correlation between pre-treatment serum carcinoembryonic antigen levels and genotypes in a large population of Chinese people with advanced lung adenocarcinoma

BACKGROUND

A positive correlation between serum carcinoembryonic antigen (CEA) levels and epidermal growth factor receptor (EGFR) mutations has been reported in lung adenocarcinoma patients.

AIM

To investigate retrospectively whether serum CEA levels are also associated with genotypes in a large population of advanced lung adenocarcinoma.

METHODS

A large cohort of 701 patients with advanced lung adenocarcinoma was studied retrospectively.

RESULTS

EGFR mutations were found in 47.5% (333/701) of advanced lung adenocarcinoma patients, being identified at high frequencies in never-smokers, females, and in patients with abnormal pre-treatment serum CEA levels (53.1% vs 37.5%, P < 0.001). In contrast, anaplastic lymphoma kinase gene rearrangements were found in 7.8% (55/701) of patients, being identified at high frequencies in younger patients, and in patients with normal CEA levels (11.5% vs 5.8%, P = 0.012). Serum CEA levels were divided into four groups: <5, 5-19, 20-99 and ≥100 ng/mL. The rate of EGFR mutations significantly increased as the serum CEA levels increased (37.5%, 49.5%, 53.9% and 57.7%, respectively, P < 0.001). Anaplastic lymphoma kinase gene rearrangements showed the opposite result (11.5%, 7.1%, 5.7% and 4.1%, respectively, P = 0.044). A multivariate analysis revealed that higher pre-treatment serum CEA levels were independently associated with EGFR mutations (95% CI: 1.291-2.487, P < 0.001), but normal serum CEA levels were independently associated with anaplastic lymphoma kinase gene rearrangements (95% CI: 0.275-0.842, P = 0.010).

CONCLUSION

Our study demonstrated that a significant association exists between the serum CEA levels and genotypes in patients with advanced lung adenocarcinoma.

[A Review of EGFR-TKIs Therapy of Non-small Cell Lung Cancer with Uncommon EGFR Mutations]

肺癌是目前最常见的癌症，也是导致癌症死亡的首要原因。非小细胞肺癌（non-small cell lung cancer, NSCLC）占85%以上，且高达50%的亚洲NSCLC患者携带表皮生长因子受体（epidermal growth factor receptor, EGFR）基因突变。研究证明，伴有EGFR突变的NSCLC患者接受表皮生长因子受体-酪氨酸激酶抑制剂（epidermal growth factor receptor-tyrosine kinase inhibitors, EGFR-TKIs）治疗能获得更好的生存结果。然而，因为EGFR罕见突变相对治疗效果较差，会对研究结果带来负面影响，所以大部分研究EGFR-TKIs疗效的临床试验都不包含罕见突变患者，另外EGFR罕见突变本身就少见，就导致临床试验中这部分患者数量较少。由于EGFR罕见突变样本量少且具有高度异质性，EGFR-TKIs对EGFR罕见突变患者的疗效仍然不清楚。本文就EGFR罕见突变与EGFR-TKIs的疗效关系进行综述，为携带EGFR罕见突变的NSCLC患者合理选择治疗方式提供指导和建议。

Heterogeneous Responses to Epidermal Growth Factor Receptor (EGFR) Tyrosine Kinase Inhibitors (TKIs) in Patients with Uncommon EGFR Mutations: New Insights and Future Perspectives in this Complex Clinical Scenario

Uncommon Epidermal Growth Factor Receptor (EGFR) mutations represent a distinct and highly heterogeneous subgroup of Non-Small Cell Lung Cancers (NSCLCs), that accounts for approximately 10% of all EGFR-mutated patients. The incidence of uncommon EGFR mutations is growing, due to the wider adoption of next-generation sequencing (NGS) for diagnostic purposes, which enables the identification of rare variants, usually missed with available commercial kits that only detect a limited number of EGFR mutations. However, the sensitivity of uncommon mutations to first- and second-generation EGFR Tyrosine Kinase Inhibitors (TKIs) is widely heterogeneous and less well known, compared with classic mutations (i.e., exon 19 deletions and exon 21 L858R point mutation), since most of the pivotal studies with EGFR TKIs in the first line, with few exceptions, excluded patients with rare and/or complex variants. Recently, the third generation EGFR TKI osimertinib further revolutionized the therapeutic algorithm of EGFR-mutated NSCLC, but its role in patients harboring EGFR mutations besides exon 19 deletions and/or L858R is largely unknown. Therefore, a better knowledge of the sensitivity of uncommon mutations to currently available EGFR TKIs is critical to guiding treatment decisions in clinical practice. The aim of this paper is to provide a comprehensive overview of the treatment of NSCLC patients harboring uncommon EGFR mutations with currently approved therapies and to discuss the emerging therapeutic opportunities in this peculiar subgroup of patients, including chemo-immunotherapy combinations, next-generation EGFR TKIs, and novel targeted agents.

Different subtypes of EGFR exon19 mutation can affect prognosis of patients with non-small cell lung adenocarcinoma

Aims

In this study, we determined whether different subtypes of epidermal growth factor receptor (EGFR) exon19 mutation are associated with the therapeutic effect of EGFR-tyrosine kinase inhibitors (TKIs) on advanced non-small cell lung adenocarcinoma.

Methods

A total of 122 patients with stage III or IV non-small cell lung adenocarcinoma were retrospectively reviewed. Clinical characteristics of these patients, including progression-free survival (PFS) outcome for EGFR-TKI treatment, were analyzed.

Results

According to the mutation pattern, we classified the in-frame deletions detected on EGFR Exon19 into three different types: codon deletion (CD), with a deletion of one or more original codons; codon substitution and skipping (CSS), with a deletion of one or two nucleotides but the residues could be translated into a new amino acid without changing following amino acid sequence; CD or CSS plus single nucleotide variant (SNV) (CD/CSS+SNV), exclude CD or CSS, there’s another SNV nearby the deletion region. The clinical characteristics of three groups were analyzed and as a result, no significant difference was found. By comparing the average number of missing bases and amino acids of the three mutation subtypes, it could be discovered that the number of missing bases and amino acids of the three mutation subtypes is diverse, and group CSS> group CD> group CD/CSS+SNV. Finally, survival analysis was performed between three groups of patients. The median PFS of group CD, group CSS and group CD/CSS+SNV was 11 months, 9 months and 14 months respectively. There was a distinct difference in the PFS between group CSS and group CD/CSS+SNV (P = 0.035<0.05), and the PFS of group CD/CSS+SNV was longer.

Conclusions

Different mutation subtypes of EGFR exon19 can predict the therapeutic effect of EGFR-TKIs on advanced non-small cell lung adenocarcinoma.