Potential genetic modifiers for somatic EGFR mutation in lung cancer: a meta-analysis and literature review

Lung cancer in patients who have never smoked - an emerging disease

Lung cancer is the most common cause of cancer-related deaths globally. Although smoking-related lung cancers continue to account for the majority of diagnoses, smoking rates have been decreasing for several decades. Lung cancer in individuals who have never smoked (LCINS) is estimated to be the fifth most common cause of cancer-related deaths worldwide in 2023, preferentially occurring in women and Asian populations. As smoking rates continue to decline, understanding the aetiology and features of this disease, which necessitate unique diagnostic and treatment paradigms, will be imperative. New data have provided important insights into the molecular and genomic characteristics of LCINS, which are distinct from those of smoking-associated lung cancers and directly affect treatment decisions and outcomes. Herein, we review the emerging data regarding the aetiology and features of LCINS, particularly the genetic and environmental underpinnings of this disease as well as their implications for treatment. In addition, we outline the unique diagnostic and therapeutic paradigms of LCINS and discuss future directions in identifying individuals at high risk of this disease for potential screening efforts.

Cerebrospinal fluid ctDNA testing shows an advantage over plasma ctDNA testing in advanced non-small cell lung cancer patients with brain metastases

Background

Brain metastases (BM), including brain parenchyma metastases (BPM) and leptomeningeal metastases (LM), are devastating metastatic complications in advanced cancer patients. Next-generation sequencing (NGS) is emerging as a new promising tool for profiling cancer mutation, which could facilitate the diagnosis of cancer. This retrospective study aimed to investigate the molecular genetic characteristics of non-small cell lung cancer (NSCLC) patients with BPM and LM using NGS.

Methods

Cerebrospinal fluid (CSF) samples and paired plasma samples were collected from 37 patients of NSCLC-BM. We profiled genetic mutation characteristics using NGS from NSCLC-BM by comparing CSF circulating tumour DNA (ctDNA) with plasma ctDNA and primary tumour tissues.

Results

Among the 37 patients with NSCLC-BM, 28 patients had LM with or without BPM, while 9 patients only had BPM. Driver and drug-resistant mutations in primary tumours with LM included: EGFR L858R (10, 35.7%), EGFR 19del (6, 21.4%), EGFR L858R+MET (1, 3.6%), EGFR L858R+S768I (1, 3.6%), ALK (2, 7.1%), ROS1 (1, 3.6%), negative (5, 17.9%), and unknown (2, 7.1%). In patients with NSCLC-LM, the detection rate and abundance of ctDNA in the CSF were significantly higher than those in paired plasma. The main driver mutations of NSCLC-LM remained highly consistent with those of the primary tumours, along with other unique mutations. Circulating tumour DNA was negative in the CSF samples of BPM patients. Patients with BMP had a higher ratio of EGFR 19del than L858R mutation (55.6% vs 11.1.%), whereas NSCLC patients with LM had a higher ratio of EGFR L858R than 19del mutation (50.0% vs 25.0%). Most patients with positive plasma ctDNA results were male (p = 0.058) and in an unstable state (p = 0.003).

Conclusion

Our study indicated that the CSF ctDNA detected by NGS may reflect the molecular characteristics and heterogeneity of NSCLC-LM. Timely screening of patients with NSCLC for CSF ctDNA, especially for patients with positive plasma ctDNA, may facilitate the early detection of LM. Furthermore, patients with the EGFR 19del may have a higher risk of developing BPM.

Higher TP53 somatic mutation prevalence from liquid biopsy analysis in ever smoker non-small-cell lung cancer patients

OBJECTIVE

Cigarette smoking is a primary risk factor, linked to 80% of LC deaths. TP53, a key gene, is implicated in various cancers, with TP53 alterations in 36.7% of cancers. This research aims to investigate TP53 mutations detected in NSCLC patients by liquid biopsy and explore the relationship between these mutations and smoking history.

MATERIAL AND METHOD

The study enrolled a total of 340 patients diagnosed with non-small cell lung cancer (NSCLC). For sequencing, the Illumina NextSeq 500 system was utilized. The oncogenicity of the variants was assessed according to the ClinGen/CGC/VICC SOP and the variants were categorized into four tiers according to AMP/ASCO/CAP.

RESULTS

The most common mutations were in TP53 (48.7%), followed by EGFR, PIK3CA, and PTEN. Missense mutations were frequent, with TP53 and EGFR having higher rates in ever-smokers. No indels or complex mutations were found in ever-smokers. Patient age ranged from 20 to 86 years. Tier I-II variants were more common in ever-smokers, while Tier III variants were prevalent in never-smokers. TP53 mutations were more frequent in ever-smokers, showing a strong association with smoking. Domain distribution showed differences in PIK3CA. Transversion/transition ratios varied by gene and smoking status.

DISCUSSION

The presence of TP53 mutations is strongly associated with both cigarette smoking and elevated Tv/Ti ratios. The tier status of TP53, EGFR, and PTEN variants does not show a specific domain distribution, but interesting associations are observed between the tier status and domain distribution in PIK3CA variants. Therefore, further comprehensive investigations are needed to explore this entity, as well as the underlying factors contributing to the increased Tv/Ti rates in the TP53 gene. Such research will provide deeper insights into the genetic alterations associated with smoking and tumor heterogeneity, ultimately aiding in the development of targeted therapies.

Rate of Pathogenic Germline Variants in Patients With Lung Cancer

PURPOSE

Germline genetic testing (GGT) is now recommended for all patients diagnosed with ovarian or pancreatic cancer and for a large proportion of patients based solely on a diagnosis of colorectal or breast cancer. However, GGT is not yet recommended for all patients diagnosed with lung cancer (LC), primarily because of a lack of evidence that supports a significant frequency of identifying pathogenic germline variants (PGVs) in these patients. This study characterizes GGT results in a cohort of patients with LC.

METHODS

We reviewed deidentified data for 7,788 patients with GGT (2015-2022). PGV frequencies were compared to a control cohort of unaffected individuals. GGT results were stratified by genomic ancestry, history of cancer, and PGV clinical actionability per current guidelines.

RESULTS

Of all patients with LC, 14.9% (1,161/7,788) had PGVs. The rate was similar when restricted to patients with no cancer family history (FH) or personal history (PH) of other cancers (14.3%). PGVs were significantly enriched in BRCA2, ATM, CHEK2, BRCA1, and mismatch repair genes compared with controls. Patients of European (EUR) genomic ancestry had the highest PGV rate (18%) and variants of uncertain significance were significantly higher in patients of non-EUR genomic ancestry. Of the PGVs identified, 61.3% were in DNA damage repair (DDR) genes and 95% were clinically actionable.

CONCLUSION

This retrospective study shows a LC diagnosis identifies patients with a significant likelihood of having a cancer-predisposing PGV across genomic ancestries. Enrichment of PGVs in DDR genes suggests that these PGVs may contribute to LC cancer predisposition. The frequency of PGVs among patients with LC did not differ significantly according to FH or PH of other cancers.

Two germline mutations can serve as genetic susceptibility screening makers for a lung adenocarcinoma family

OBJECTIVES

Lung cancer is the most common form of cancer and the leading cause of cancer death. For familial lung cancer, identification of causing genetic factors is essential for prevention and control of non-lung cancer in carriers.

MATERIALS AND METHODS

We studied two generations of a family with suspected inherited lung cancer susceptibility. Four individuals in this family had lung adenocarcinoma. To identify the gene(s) that cause the lung cancer in this pedigree, we extracted DNA from the peripheral blood of four cancer individuals and blood from three cancer-free family members as the control and performed whole-genome sequencing. Our filtering strategy includes, assessment of allele frequency, functional affection on amino acids, mutation accumulation, phased blocks and evolution analysis towards the alterations.

RESULTS

We identified two possible mutations, including PLEKHM2 (D134N) and MCC (R448Q) in all affected family members but did not found in the control group. Then, we performed a genetic susceptibility screening for 10 non-lung cancer relatives and found two individuals with PLEKHM2 (D134N) mutation, two with MCC (R448Q) mutation and one carrying both mutations. 3 carriers performed LDCT scan and 2 of them carried MCC (R448Q) also had ground-glass opacity (GGO) lesion in their lung.

CONCLUSION

Our data suggested that WGS together with our filtering strategy was successful in identifying PLEKHM2 (D134N) and MCC (R448Q) as the possible driver mutations in this family. Genetic susceptibility screening of non-lung cancer carriers will be a useful approach to prevent and control lung cancer in families with high-risk for the disease.

Targeting the EGFR signaling pathway in cancer therapy: What's new in 2023?

INTRODUCTION

Epidermal growth factor receptor (EGFR) is frequently amplified, overexpressed, and mutated in multiple cancers. In normal cell physiology, EGFR signaling controls cellular differentiation, proliferation, growth, and survival. During tumorigenesis, mutations in EGFR lead to increased kinase activity supporting survival, uncontrolled proliferation, and migratory functions of cancer cells. Molecular agents targeting the EGFR pathway have been discovered, and their efficacy has been demonstrated in clinical trials. To date, 14 EGFR-targeted agents have been approved for cancer treatments.

AREAS COVERED

This review describes the newly identified pathways in EGFR signaling, the evolution of novel EGFR-acquired and innate resistance mechanisms, mutations, and adverse side effects of EGFR signaling inhibitors. Subsequently, the latest EGFR/panEGFR inhibitors in preclinical and clinical studies have been summarized. Finally, the consequences of combining immune checkpoint inhibitors and EGFR inhibitors have also been discussed.

EXPERT OPINION

As new mutations are threatened against EGFR-tyrosine kinase inhibitors (TKIs), we suggest the development of new compounds targeting specific mutations without inducing new mutations. We discuss potential future research on developing EGFR-TKIs specific for exact allosteric sites to overcome acquired resistance and reduce adverse events. The rising trend of EGFR inhibitors in the pharma market and their economic impact on real-world clinical practice are discussed.

Organoid drug screening report for a non-small cell lung cancer patient with EGFR gene mutation negativity: A case report and review of the literature

Patients with non-small cell lung cancer (NSCLC) who carry epidermal growth factor receptor (EGFR) mutations can benefit significantly from EGFR tyrosine kinase inhibitors (EGFR TKIs). However, it is unclear whether patients without EGFR mutations cannot benefit from these drugs. Patient-derived tumor organoids (PDOs) are reliable in vitro tumor models that can be used in drug screening. In this paper, we report an Asian female NSCLC patient without EGFR mutation. Her tumor biopsy specimen was used to establish PDOs. The treatment effect was significantly improved by anti-tumor therapy guided by organoid drug screening.

An efficient five-lncRNA signature for lung adenocarcinoma prognosis, with AL606489.1 showing sexual dimorphism

Background: Lung adenocarcinoma (LUAD) is a sex-biased and easily metastatic malignant disease. A signature based on 5 long non-coding RNAs (lncRNAs) has been established to promote the overall survival (OS) prediction effect on LUAD.

Methods: The RNA expression profiles of LUAD patients were obtained from The Cancer Genome Atlas. OS-associated lncRNAs were identified based on the differential expression analysis between LUAD and normal samples followed by survival analysis, univariate and multivariate Cox proportional hazards regression analyses. OS-associated lncRNA with sex dimorphism was determined based on the analysis of expression between males and females. Functional enrichment analysis of the Gene Ontology (GO) terms and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways was performed to explore the possible mechanisms of 5-lncRNA signatures.

Results: A 5-lncRNA signature (composed of AC068228.1, SATB2-AS1, LINC01843, AC026355.1, and AL606489.1) was found to be effective in predicting high-risk LUAD patients as well as applicable to female and male subgroups and <65-year and ≥65-year age subgroups. The forecasted effect of the 5-lncRNA signature was more efficient and stable than the TNM stage and other clinical risk factors (such as sex and age). Functional enrichment analysis revealed that the mRNA co-expressed with these five OS-related lncRNAs was associated with RNA regulation within the nucleus. AL606489.1 demonstrated a sexual dimorphism that may be associated with microtubule activity.

Conclusion: Our 5-lncRNA signature could efficaciously predict the OS of LUAD patients. AL606489.1 demonstrated gender dimorphism, which provides a new direction for mechanistic studies on sexual dimorphism.

Germline Testing of Patients With Non-small Cell Lung Cancers Demonstrating Incidentally Uncovered BRCA2 Apparent Pathogenic Germline Variants

Tumor next generation sequencing (NGS) is used to interrogate nearly every non-small cell lung cancer (NSCLC) for the purpose of identifying actionable genetic alterations. Occasionally, tumor NGS also uncovers "incidental" apparent pathogenic germline variants (PGVs), with BRCA2 being among the most common of those. If germline testing confirms a BRCA2 PGV in a patient with NSCLC, therapies targeting that BRCA2 PGV might be considered, if the patient has exhausted standard NSCLC therapeutic options. Surveillance and preventive therapies for BRCA2-related cancers would be recommended or considered for that patient, as well as for family members found to carry that same BRCA2 PGV. Here, I offer my perspective related to the evidence supporting and against germline testing in patients with NSCLCs that show incidental BRCA2 apparent PGVs. I use an example to underscore how important it is to explain to patients, before tumor NGS, the possibility of uncovering an incidental PGV. I also review the myriad uncertainties related to identifying a BRCA2 PGV, when the sole indication for germline testing was the uncovering of the incidental BRCA2 apparent PGV.

Synchronous driver gene alterations (EGFR L858R, T790M, and ROS1) rearrangements in a patient with early-stage lung adenocarcinoma

Concurrent EGFR mutation and ROS1 rearrangement is a rare event in early-stage non-small-cell lung cancer. In addition, a co-occurring de novo EGFR T790M mutation in such a case is extremely rare. We encountered a 72-year-old woman who developed 3 early-stage lung lesions synchronously, one each harboring EGFR L858R, ROS1 rearrangement, and EGFR L858R and de novo T790M. These three nodules were pathologically time-matched lepidic predominant adenocarcinoma with small invasive lesions, which may reflect the concept of field cancerization with driver mutations.

Factors associated with time to EGFR TKI treatment in patients with non-squamous metastatic non-small-cell lung cancer

Aim: Assess factors associated with EGFR TKI initiation among patients with metastatic non-small-cell lung cancer (mNSCLC). Patients & methods: Medicare Part D patients diagnosed with non-squamous mNSCLC and starting an EGFR TKI within 1 year of diagnosis were selected from the Surveillance, Epidemiology and End Results (SEER)-Medicare database. Associations between patient characteristics and time from diagnosis to treatment initiation (time to treatment [TTT]) were analyzed. Results: Among the sample (n = 890), the patients who were younger, Black or from rural communities had significantly longer TTT. Patients who did not receive surgery, who were Asian and those with brain metastases had significantly shorter TTT. Conclusion: Patient demographics and clinical characteristics may affect timeliness of EGFR TKI treatment for mNSCLC. Future research should examine potential barriers to treatment.

The interaction effects of FEN1 rs174538 polymorphism and polycyclic aromatic hydrocarbon exposure on damage in exon 19 and 21 of EGFR gene in coke oven workers

Polycyclic aromatic hydrocarbon (PAH) exposure and genetic susceptibility were conductive to genotoxic effects including gene damage, which can increase mutational probability. We aimed to explore the dose-effect associations of PAH exposure with damage of exons of epidermal growth factor receptor (EGFR) and breast cancer susceptibility gene 1 (BRCA1), as well as their associations whether modified by Flap endonuclease 1 (FEN1) genotype. Two hundred eighty-eight coke oven male workers were recruited, and we detected the concentration of 1-hydroxypyrene (1-OH-pyr) as PAH exposure biomarker in urine and examined base modification in exons of EGFR and BRCA1 respectively, and genotyped FEN1 rs174538 polymorphism in plasma. We found that the damage indexes of exon 19 and 21 of EGFR (EGFR-19 and EGFR-21) were both significantly associated with increased urinary 1-OH-pyr (both P_trend < 0.001). The levels of urinary 1-OH-pyr were both significantly associated with increased EGFR-19 and EGFR-21 in both smokers and nonsmokers (both P < 0.001). Additionally, we observed that the urinary 1-OH-pyr concentrations were linearly associated with both EGFR-19 and EGFR-21 only in rs174538 GA+AA genotype carriers (both P < 0.001). Moreover, FEN1rs rs174538 showed modifying effects on the associations of urinary 1-OH-pyr with EGFR-19 and EGFR-21 (both P_interaction < 0.05). Our findings revealed the linear dose-effect association between exon damage of EGFR and PAH exposure and highlight differences in genetic contributions to exon damage and have the potential to identify at-risk subpopulations who are susceptible to adverse health effects induced by PAH exposure.

EGFR Inhibitors Plus Bevacizumab are Superior Than EGFR Inhibitors Alone as First-Line Setting in Advanced NSCLC With EGFR Mutations and BIM Deletion Polymorphisms (BIM-CLICaP)

PURPOSE

BIM activation is essential for epidermal growth factor receptor ( EGFR)-tyrosine kinase inhibitor (TKI)–triggered apoptosis in EGFR-mutant non–small-cell lung cancer (NSCLC). A deletion in the intron two of the BIM gene results in generation of alternatively spliced isoforms that impairs their apoptotic response to TKIs, conferring the NSCLC cells intrinsic resistance to these medications. Patients with both alterations have poor clinical evolution. The current study aimed to investigate the clinical efficacy and tolerability of EGFR-TKIs plus bevacizumab (Bev) versus EGFR-TKIs alone as first-line treatment in advanced NSCLC patients with EGFR mutations and BIM deletions ( BIMdel).

MATERIALS AND METHODS

A retrospective analysis was conducted. BIMdel was detected using polymerase chain reaction analysis and direct sequencing of DNA. BIM protein expression was investigated by immunohistochemistry, and BIM mRNA levels by reverse transcriptase-polymerase chain reaction. Clinical characteristics, overall survival, progression-free survival (PFS), overall response rate (ORR), and treatment-related adverse events were compared between both groups.

RESULTS

Thirty-three patients were included; 15 received EGFR-TKIs, and 18 received EGFR-TKIs plus Bev. The median age was 63 years, with a majority of recruited female patients. All included individuals had an Eastern Cooperative Oncology Group performance score of 2 or less. The addition of Bev resulted in a significantly higher ORR (94.4% v 40%, P > .001). Median PFS was longer with the use of the combination therapy (11.12 v 7.87 months; P = .001). Median overall survival tended to be longer in the EGFR-TKIs plus Bev (30.9 v 25.4 months; P = .06) but failed to reach statistical significance. Response in terms of both partial and complete as well as overall favorably affected PFS.

CONCLUSION

EGFR-TKIs plus Bev conferred a significantly higher ORR and PFS in advanced NSCLC patients with EGFR mutation and BIMdel. Further prospective studies are needed to validate these findings.

Transcatheter arterial chemoembolization improves clinical efficacy and life quality of patients with lung cancer and reduces adverse reactions

OBJECTIVE

To determine the clinical efficacy and safety of transcatheter arterial chemoembolization (TACE) for patients with lung cancer (LC).

METHODS

A total of 513 inpatients with LC admitted to our hospital from January 2012 to January 2020 were analyzed retrospectively. Based on different treatment methods, they were assigned into a control group (CG; n=249) for traditional bronchial artery infusion (BAI) and an experimental group (EG; n=264) for TACE, with shared chemotherapy drugs and treatment courses. The two groups were compared with respect to clinical efficacy, pre- and post-treatment pulmonary function, adverse reactions, as well as negative emotions and quality of life (QoL) scores.

RESULTS

The curative effect in EG was far superior to CG (P<0.05). In comparison with CG, the pulmonary function in EG was better and the incidence of adverse reactions was lower after treatment (P<0.05). The negative emotions and the QoL were improved in both groups, with more distinct improvement in EG compared with CG (P<0.05).

CONCLUSIONS

With higher safety and efficacy, TACE can improve the clinical efficacy and QoL of patients with LC while relieving bad mood and reducing adverse reactions.

Germline ERBB3 mutation in familial non-small cell lung carcinoma: Expanding ErbB's role in oncogenesis

Lung cancer is the commonest cause of cancer deaths worldwide. Although strongly associated with smoking, predisposition to lung cancer is also heritable, with multiple common risk variants identified. Rarely, dominantly inherited non-small-cell lung cancer (NSCLC) has been reported due to somatic mutations in EGFR/ErbB1 and ERBB2. Germline exome sequencing was performed in a multi-generation family with autosomal dominant NSCLC, including an affected child. Tumour samples were also sequenced. Full-length wild-type (wtErbB3) and mutant ERBB3 (mutErbB3) constructs were transfected into HeLa cells. Protein expression, stability, and subcellular localization were assessed, and cellular proliferation, pAkt/Akt and pERK levels determined. A novel germline variant in ERBB3 (c.1946 T > G: p.Iso649Arg), coding for receptor tyrosine-protein kinase erbB-3 (ErbB3), was identified, with appropriate segregation. There was no loss-of-heterozygosity in tumour samples. Both wtErbB3 and mutErbB3 were stably expressed. MutErbB3-transfected cells demonstrated an increased ratio of the 80 kDa form (which enhances proliferation) compared with the full-length (180 kDa) form. MutErbB3 and wtErbB3 had similar punctate cytoplasmic localization pre- and post-epidermal growth factor stimulation; however, epidermal growth factor receptor (EGFR) levels decreased faster post-stimulation in mutErbB3-transfected cells, suggesting more rapid processing of the mutErbB3/EGFR heterodimer. Cellular proliferation was increased in mutErbB3-transfected cells compared with wtErbB3 transfection. MutErbB3-transfected cells also showed decreased pAkt/tAkt ratios and increased pERK/tERK 30 min post-stimulation compared with wtErbB3 transfection, demonstrating altered signalling pathway activation. Cumulatively, these results support this mutation as tumorogenic. This is the first reported family with a germline ERBB3 mutation causing heritable NSCLC, furthering understanding of the ErbB family pathway in oncogenesis.

The Impact of Variant Allele Frequency in EGFR Mutated NSCLC Patients on Targeted Therapy

EGFR mutations represent the most common currently targetable oncogenic driver in non-small cell lung cancer. There has been tremendous progress in targeting this alteration over the course of the last decade, and third generation tyrosine kinase inhibitors offer previously unseen survival rates among these patients. Nonetheless, a better understanding is still needed, as roughly a third of patients do not respond to targeted therapy and there is an important heterogeneity among responders. Allelic frequency, or the variant EGFR allele frequency, corresponds to the fraction of sequencing reads harboring the mutation. The allelic fraction is influenced by the proportion of tumor cells in the sample, the presence of copy number alterations but also, most importantly, by the proportion of cells within the tumor that carry the mutation. Mutations that occur early in tumor evolution, often called clonal or truncal, have a higher allelic frequency than late, subclonal mutations, and are more often drivers of cancer evolution and attractive therapeutic targets. Most, but not all, EGFR mutations are clonal. Although an exact estimate of clonal proportion is hard to derive computationally, the allelic frequency is readily available to clinicians and could be a useful surrogate. We hypothesized that tumors with low allelic frequency of the EGFR mutation will respond less favorably to targeted treatment.

Germline EGFR variants are over-represented in adolescents and young adults (AYA) with adrenocortical carcinoma

Adrenocortical Carcinoma (ACC) is a rare endocrine tumor with poor overall prognosis and 1.5-fold overrepresentation in females. In children, ACC is associated with inherited cancer syndromes with 50-80% of childhood-ACC associated with TP53 germline variants. ACC in adolescents and young adults (AYA) is rarely due to germline TP53, IGF2, PRKAR1A and MEN1 variants. We analyzed exome sequencing data from 21 children (<15y), 32 AYA (15-39y), and 60 adults (>39y) with ACC, and retained all pathogenic, likely pathogenic, and highly prioritized variants of uncertain significance. We engineered a stable lentiviral-mutant ACC cell line, harboring an EGFR variant (p.Asp1080Asn) from a 21-year-old female without germline-TP53-variant and with aggressive ACC. We found that 4.8% of the children (P = 0.004) and 6.2% of AYA (P < 0.0001), all-female participants, harbored germline EGFR variants, compared to only 0.3% of the control group. Expanding our analysis to the RTK-RAS-MAPK pathway, we found that the RTK genes have the highest number of highly prioritized germline variants in these individuals amongst all three arms of this pathway. We showed EGFR mutant cells migrate faster and are characterized by a stem-like phenotype compared to wild type cells. While EGFR inhibitors did not affect the stemness of mutant cells, Sunitinib, a multireceptor tyrosine kinase inhibitor, significantly reduced their stem-like behavior. Our data suggest that EGFR could be a novel underlying germline predisposition factor for ACC, especially in the Childhood-AYA (C-AYA) population. Further clinical validation can improve precision oncology management of this disease, which is known to have limited therapeutic options.

Spectrum of uncommon and compound epidermal growth factor receptor mutations in non-small-cell lung carcinomas with treatment response and outcome analysis: A study from India

INTRODUCTION

Mutations in the tyrosine kinase domain of the epidermal growth factor receptor gene (EGFR) are key driver alterations in lung adenocarcinomas (ADCAs). Exon 19 deletions (exon19del) and exon 21 L858R (L858R) mutations account for 70-90 % of all such alterations and predict sensitivity to EGFR tyrosine kinase inhibitors (TKIs). However, the predictive value of uncommon and compound EGFR mutations for TKIs has not been clearly established.

OBJECTIVE

To assess the spectrum of EGFR mutations in non-small-cell lung carcinoma (NSCLC), and to compare the treatment responses and outcomes among single common, single uncommon, and compound mutations.

METHOD

The study was of combined retrospective (January 2010-December 2015) and prospective (January 2016-February 2020) design spanning 10 years. Tumor samples from TKI-naive NSCLC patients were tested for EGFR mutations by a qPCR-based method. Objective response rates (ORRs) and survival outcomes were analyzed.

RESULT

In total, 1227 tumor samples were tested. EGFR mutations were detected in 391 samples (31.8 %), and included 79.5 % (311/391) single common (exon19del/L858R), 6.6 % (26/391) single uncommon (non-exon19del/L858R), and 13.8 % (54/391) compound mutations. Exon 20 T790M mutations were most prevalent among uncommon/compound mutations (40/391, 10.2 %). Overall, patients with single uncommon/compound mutations responded poorly to both EGFRTKI (47 % ORR) and chemotherapy (43 % ORR), with significantly shorter time to progression (median 7 months) compared to those with exon19del/L858R mutations (median 14.7 months). Patients with baseline T790M mutations (single/compound) were least responsive to EGFR TKIs (11 % ORR) and chemotherapy (27 % ORR) and showed the shortest progression-free survival compared to other uncommon and compound mutations.

CONCLUSION

Approximately one fifth of EGFR-mutant patients harbor uncommon and compound mutations. Unlike those with exon19del/L858R, these patients-particularly those with baseline T790M mutations-show significantly inferior response rates to treatment (EGFR TKI or chemotherapy) and early disease progression.

Association of Carbonic Anhydrase 9 Polymorphism and the Epithelial Growth Factor Receptor Mutations in Lung Adenocarcinoma Patients

Carbonic anhydrase 9 (CA9) plays a vital role in lung cancer progression. The current study explored the effect of CA9 gene polymorphisms and the epidermal growth factor receptor (EGFR) mutations on the clinicopathological characters of lung adenocarcinoma. In this study, three loci of CA9 single nucleotide polymorphism (SNP) (rs2071676 A>G, rs3829078 A>G, and rs1048638 C>A) were genotyped using the TaqMan allelic discrimination method in 193 EGFR wild type individuals and 281 EGFR mutation subjects. After adjusting for age, gender, and cigarette smoking status in logistic regression, all three CA9 SNPs illustrated a non-significant difference for the distribution between the EGFR wild type group and EGFR mutation group. Nevertheless, a significantly lower rate of CA9 SNP rs2071676 AG (adjusted odds ratio (AOR): 0.40, 95% confidence interval (CI): 0.16-0.95, p = 0.039) and AG+GG (AOR: 0.43, 95% CI: 0.18-0.98, p = 0.046) were found in the male population with L858R EGFR mutation compared to men with EGFR wild type. In addition, the CA9 SNP rs2071676 AG+GG genotype were significantly correlated to the lower tumor stage of lung adenocarcinoma in the whole study population (p = 0.044) and EGFR wild type individuals (p = 0.033). For the male population, the presence of CA9 SNP rs2071676 AG+GG genotype was also correlated to a lower tumor stage (p = 0.037) and fewer lymph node invasion (p = 0.003) in those with EGFR wild type. In conclusion, the existence of CA9 SNP rs2071676 is associated with the rate of EGFR L858R mutation in males. Furthermore, the CA9 SNP rs2071676 is correlated to lower tumor stage and lower risk for developing lymph node metastasis in lung adenocarcinoma, mainly in the EGFR wild type.