Differential significance of molecular subtypes which were classified into EGFR exon 19 deletion on the first line afatinib monotherapy

Atypical Droplet Digital Polymerase Chain Reaction Patterns That Indicate Uncommon but Clinically Actionable EGFR Mutations in Lung Cancer

CONTEXT

Droplet digital polymerase chain reaction (ddPCR) is a sensitive method to detect common pathogenic EGFR mutations in non-small cell lung cancer. Although targeted assays have not been specifically designed to detect them, uncommon EGFR mutations have been linked to response to targeted therapy.

OBJECTIVE

To describe atypical ddPCR patterns that correspond to uncommon but clinically actionable EGFR mutations.

DESIGN

A cohort of 1134 consecutive non-small cell lung cancers that underwent targeted next-generation sequencing was reviewed. Uncommon EGFR mutations involving probe binding sites were evaluated by ddPCR.

RESULTS

Two hundred fifty-five of 1134 cancers (22.5%) harbored pathogenic EGFR mutations. One hundred eighty-six of 255 (72.9%) had canonical EGFR exon 19 deletion or exon 21 p.L858R variants designed for detection by ddPCR. An additional 25 of 255 cases (9.8%) had uncommon EGFR mutations within the probe-binding site, including 1 case with concurrent uncommon mutations in both exon 19 and exon 21. These mutations included uncommon EGFR exon 19 deletions (n = 6), EGFR exon 19 substitutions p.L747P (n = 3) and p.L747A (n = 1), dinucleotide substitutions leading to EGFR p.L858R (n = 5), EGFR exon 21 substitutions p.K860I (n = 1) and p.L861Q (n = 9), and EGFR p.[L858R;K860I] (n = 1). Droplet digital polymerase chain reaction generated atypical but reproducible signal for each of these uncommon variants.

CONCLUSIONS

Droplet digital polymerase chain reaction analysis of uncommon pathogenic EGFR variants can yield unique and reproducible results. Recognition of atypical patterns in EGFR ddPCR testing can prompt confirmatory molecular testing and aid appropriate targeted therapy selection for patients with non-small cell lung cancer.

RELAY, Erlotinib Plus Ramucirumab in Untreated, EGFR-Mutated, Metastatic NSCLC: Outcomes by EGFR Exon 19 Deletion Variants

Introduction

EGFR gene mutations are drivers of NSCLC. The RELAY double-blind, placebo (PBO)-controlled phase 3 study revealed superior progression-free survival (PFS) for ramucirumab plus erlotinib (RAM + ERL) versus PBO (PBO + ERL) in patients with untreated advanced NSCLC and an EGFR-activating mutation. This exploratory analysis evaluated potential associations between EGFR exon 19 deletion (ex19del) variants and clinical outcomes.

Methods

Patients (N = 449) were randomized (1:1) to RAM plus ERL or PBO plus ERL. Plasma samples were collected at baseline, on treatment, and at 30-day post-study treatment discontinuation follow-up. Baseline and treatment-emergent gene alterations were investigated by Guardant360 next-generation sequencing. Patients with a valid baseline plasma sample and ex19del were included (RAM + ERL, n = 62; PBO + ERL, n = 72).

Results

The most common ex19del variant was E746_A750del (67.2%); EGFR E746 deletions (E746del) occurred more frequently than L747 deletions (74.6% versus 25.4%, respectively). TP53 mutations were the most frequently co-occurring baseline gene alterations. With treatment arms combined, median PFS was 18.0 months versus 12.5 months for patients with uncommon (non-E746_A750del, n = 44) versus common (E746_A750del, n = 90) ex19del variants (hazard ratio [HR] = 1.657 [95% confidence interval or CI:1.044-2.630]). Median PFS was longer with RAM plus ERL versus PBO plus ERL for patients with the common (15.2 versus 9.9 mo; HR = 0.564 [95% CI: 0.344-0.926]) and E746del (15.4 versus 9.9 mo; HR = 0.587 [95% CI: 0.363-0.951]) variants. Treatment-emergent post-progression EGFR T790M rates were higher in the common versus uncommon and E746del versus L747 deletion subgroups.

Conclusions

RAM plus ERL provides benefit and improves treatment outcomes for patients with metastatic NSCLC with EGFR ex19del variants.

Clinical outcomes of advanced NSCLC patients with different EGFR exon 19 deletion subtypes treated with first-line tyrosine kinase inhibitors: A single-center ambispective cohort study

BACKGROUND

Clinical significance of various subtypes of epidermal growth factor receptor (EGFR) exon 19 deletion (ex19del) mutation in non-small cell lung cancer (NSCLC) remains unclear.

METHODS

We analyzed EGFR ex19del subtypes in NSCLC patients receiving first-line tyrosine kinase inhibitor (TKI) therapy at our center (January 2018-June 2022) and correlated them with median progression-free survival (mPFS) and median overall survival (mOS).

RESULTS

We identified 17 different EGFR ex19del variants in 101 patients. Between the classic (E746_A750del, 64.4%) and nonclassic groups (the rest variants), no significant difference was observed in mPFS (13.5 vs. 19.3 months, p = 0.18) or mOS (44.1 vs. 77.0 months, p = 0.06). mPFS showed no significant difference between ex19del subgroups classified based on the presence of insertion (ex19delins), starting position or length of deletion. However, patients with ex19delins starting at E746 showed longer mPFS than the others (29.7 vs. 12.5 months, p = 0.04), and patients with ex19del of 15 nucleotides had shorter mOS than the others (44.1 vs. 77.0 months, p = 0.03). In multivariate analysis, ex19delins independently predicted a better PFS (HR = 0.311, p = 0.03); however, 15 nucleotide deletion was no longer associated with OS (HR = 0.181, p = 0.11). Secondary T790M mutation incidence was significantly higher in the ex19del subgroup starting at E746 than the others (64.7% vs. 30.8%, p = 0.04).

CONCLUSIONS

Our study revealed potential differences in TKI efficacy, resistance mechanism, and prognosis of various EGFR ex19del subtypes in NSCLC, underscoring the need for precise selection of first-line therapy.

Biosensors for the detection of lung cancer biomarkers: A review on biomarkers, transducing techniques and recent graphene-based implementations

Lung cancer remains the leading cause of cancer-related death. In addition to chest X-rays and computerised tomography, the detection of cancer biomarkers serves as an emerging diagnostic tool for lung cancer. This review explores biomarkers including the rat sarcoma gene, the tumour protein 53 gene, the epidermal growth factor receptor, the neuron-specific enolase, the cytokeratin-19 fragment 21-1 and carcinoembryonic antigen as potential indicators of lung cancer. Biosensors, which utilise various transduction techniques, present a promising solution for the detection of lung cancer biomarkers. Therefore, this review also explores the working principles and recent implementations of transducers in the detection of lung cancer biomarkers. The transducing techniques explored include optical techniques, electrochemical techniques and mass-based techniques for detecting biomarkers and cancer-related volatile organic compounds. Graphene has outstanding properties in terms of charge transfer, surface area, thermal conductivity and optical characteristics, on top of allowing easy incorporation of other nanomaterials. Exploiting the collective merits of both graphene and biosensor is an emerging trend, as evidenced by the growing number of studies on graphene-based biosensors for the detection of lung cancer biomarkers. This work provides a comprehensive review of these studies, including information on modification schemes, nanomaterials, amplification strategies, real sample applications, and sensor performance. The paper concludes with a discussion of the challenges and future outlook of lung cancer biosensors, including scalable graphene synthesis, multi-biomarker detection, portability, miniaturisation, financial support, and commercialisation.

Clinical importance of the range of detectable variants between the Oncomine Dx target test and a conventional single-gene test for EGFR mutation

Although we have experienced some cases with discordant results between the Oncomine Dx target test (ODxTT) and conventional single gene tests for detecting EGFR alterations, the clinical efficacy of EGFR-TKIs in these discordant cases remains little known. We retrospectively reviewed consecutive patients with non-small-cell lung cancer whose FFPE samples were simultaneously submitted for the ODxTT, and a PNA-LNA PCR clamp test. We evaluated the clinical efficacy of EGFR-TKIs in patients with discordant results between the two tests, focusing on the common EGFR mutations. Among 444 successful results, 10 patients had discordant results for common EGFR mutations (9 Ex 19 deletion and 1 Ex 21 L858R mutation), and all of these were detected only by the PNA-LNA PCR clamp test. Among six discordant cases treated with EGFR-TKI, the mutations detected in 3 patients were not included in the list of detectable variants that are reportable by the ODxTT, while the mutations detected in the other 3 patients were included in the list. For all three discordant cases harboring the mutations not reportable by the ODxTT, good clinical responses were demonstrated. However, among the other three discordant cases harboring the mutations reportable by the ODxTT, only one patient had a clinical response with short duration. Among the discordant cases for common EGFR mutations between the ODxTT and the conventional single gene test, there are a certain number of suitable patients responsive to EGFR-TKIs, especially when the cause of the discordant results comes from the difference in the range of detectable variants that are reportable between the tests.

Allele-specific activation, enzyme kinetics, and inhibitor sensitivities of EGFR exon 19 deletion mutations in lung cancer

Epidermal growth factor receptor (EGFR) mutations are detected in approximately 30% of all lung adenocarcinomas, and the most common EGFR mutation occurring in ∼50% of patients is termed “exon 19 deletion” (ex19del). Despite the existence of dozens of different genomic variants comprising what is generically referred to clinically as ex19del, clinicians currently do not distinguish between ex19del variants in considering treatment options, and differences between ex19del variants are largely unstudied in the broader scientific community. Herein, we describe functional differences between distinct EGFR ex19del variants attributable to the structural features of each variant. These findings suggest a possible explanation for observed differences in patient outcomes stratified by ex19del subtype and reinforce the need for allele-specific considerations in clinical treatment decision-making.

Oncogenic mutations within the epidermal growth factor receptor (EGFR) are found in 15 to 30% of all non–small-cell lung carcinomas. The term exon 19 deletion (ex19del) is collectively used to refer to more than 20 distinct genomic alterations within exon 19 that comprise the most common EGFR mutation subtype in lung cancer. Despite this heterogeneity, clinical treatment decisions are made irrespective of which EGFR ex19del variant is present within the tumor, and there is a paucity of information regarding how individual ex19del variants influence protein structure and function. Herein, we identified allele-specific functional differences among ex19del variants attributable to recurring sequence and structure motifs. We built all-atom structural models of 60 ex19del variants identified in patients and combined molecular dynamics simulations with biochemical and biophysical experiments to analyze three ex19del mutations (E746_A750, E746_S752 > V, and L747_A750 > P). We demonstrate that sequence variation in ex19del alters oncogenic cell growth, dimerization propensity, enzyme kinetics, and tyrosine kinase inhibitor (TKI) sensitivity. We show that in contrast to E746_A750 and E746_S752 > V, the L747_A750 > P variant forms highly active ligand-independent dimers. Enzyme kinetic analysis and TKI inhibition experiments suggest that E746_S752 > V and L747_A750 > P display reduced TKI sensitivity due to decreased adenosine 5′-triphosphate K_m. Through these analyses, we propose an expanded framework for interpreting ex19del variants and considerations for therapeutic intervention.

Metabolic complete tumor response in a patient with epidermal growth factor receptor mutant non-small cell lung cancer treated with a reduced dose of afatinib

Tyrosine kinase inhibitors (TKIs) targeting epidermal growth factor receptor (EGFR) are the first-line treatment for EGFR-mutant non-small cell lung cancer. Toxicities related to EGFR-TKIs include skin rash, paronychia, and diarrhea, which in some cases can lead to dose reductions or treatment interruptions. Herein, we report the case of a 51-year-old woman affected by advanced adenocarcinoma harboring an exon 19 deletion in the EGFR gene, who was treated with second-generation EGFR-TKI following a scheduled gradual dose reduction to better manage toxicities. Following prescription labeling, treatment was initiated at a dose of 40 mg daily. After a few months, the dose was reduced to 30 mg daily owing to grade 3 skin toxicity. A metabolic complete tumor response was observed after 1 year of treatment, then therapy was continued at 20 mg daily, enabling disease stabilization. In conclusion, low dose afatinib was effective in an EGFR-mutant non-small cell lung cancer patient who required dose reductions to better manage toxicities.

Chronicles of EGFR Tyrosine Kinase Inhibitors: Targeting EGFR C797S Containing Triple Mutations

Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase widely expressed in many cancers such as non-small cell lung cancer (NSCLC), pancreatic cancer, breast cancer, and head and neck cancer. Mutations such as L858R in exon 21, exon 19 truncation (Del19), exon 20 insertions, and others are responsible for aberrant activation of EGFR in NSCLC. First-generation EGFR tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib have clinical benefits for EGFR-sensitive (L858R and Del19) NSCLC patients. However, after 10-12 months of treatment with these inhibitors, a secondary T790M mutation at the gatekeeper position in the kinase domain of EGFR was identified, which limited the clinical benefits. Second-generation EGFR irreversible inhibitors (afatinib and dacomitinib) were developed to overcome this T790M mutation. However, their lack of selectivity toward wild-type EGFR compromised their clinical benefits due to serious adverse events. Recently developed third-generation irreversible EGFR TKIs (osimertinib and lazertinib) are selective toward driving mutations and the T790M mutation, while sparing wildtype EGFR activity. The latest studies have concluded that their efficacy was also compromised by additional acquired mutations, including C797S, the key residue cysteine that forms covalent bonds with irreversible inhibitors. Because second- and thirdgeneration EGFR TKIs are irreversible inhibitors, they are not effective against C797S containing EGFR triple mutations (Del19/T790M/C797S and L858R/T790M/C797S). Therefore, there is an urgent unmet medical need to develop next-generation EGFR TKIs that selectively inhibit EGFR triple mutations via a non-irreversible mechanism.

Quinoline–hydrazone hybrids as dual mutant EGFR inhibitors with promising metallic nanoparticle loading: rationalized design, synthesis, biological investigation and computational studies

A novel quinoline–hydrazone hybrid induced apoptosis in MCF-7 cells through dual mutant EGFR inhibition with promising metallic nanoparticle loading.

Targeted Next-Generation Sequencing Analysis Predicts the Recurrence in Resected Lung Adenocarcinoma Harboring EGFR Mutations

Targeted NGS, widely applied to identify driver oncogenes in advanced lung adenocarcinoma, may also be applied to resected early stage cancers. We investigated resected EGFR-mutated lung adenocarcinoma mutation profiles to evaluate prognostic impacts. Tissues from 131 patients who had complete resection of stage I-IIIA EGFR-mutated lung adenocarcinoma were analyzed by targeted NGS for 207 cancer-related genes. Recurrence free survival (RFS) was estimated according to genetic alterations using the Kaplan-Meier method and Cox proportional regression analysis. The relapse rate was 25.2% (33/131). Five-year RFS of stages IA, IB, II, and IIIA were 82%, 75%, 35%, and 0%, respectively (p < 0.001). RFS decreased with the number of co-mutations (p = 0.025). Among co-mutations, the CTNNB1 mutation was associated with short RFS in a multivariate analysis (hazard ratio: 5.4, 95% confidence interval: 2.1-14.4; p = 0.001). TP53 mutations were associated with short RFS in stage IB-IIIA (p = 0.01). RFS was shorter with EGFR exon 19 deletion (19-del) than with mutation 21-L858R in stage IB-IIIA tumors (p = 0.008). Among 19-del subtypes, pL747_P753delinS (6/56, 8.9%) had shorter RFS than pE746_A750del (39/56, 69.6%), the most frequent subtype (p = 0.004).

Recent Advances on the Role of EGFR Tyrosine Kinase Inhibitors in the Management of NSCLC With Uncommon, Non Exon 20 Insertions, EGFR Mutations

The first-line treatment of choice for patients with EGFR mutation-positive NSCLC is an EGFR tyrosine kinase inhibitor (TKI), of which five as follows are predominantly available in practice: gefitinib, erlotinib, afatinib, dacomitinib, and osimertinib. Most prospective clinical trial data with these agents are limited to patients with the common activating and sensitizing EGFR mutations as follows: exon 19 deletions and exon 21 L858R point mutations. However, 10% to 20% of patients with NSCLC harbor uncommon EGFR mutations that have variable sensitivity to different EGFR TKIs. Owing to their molecular structures, afatinib, dacomitinib, and osimertinib have broader inhibitory profiles than the first-generation agents, gefitinib and erlotinib. Nevertheless, the paucity of prospective clinical data, the wide heterogeneity of uncommon mutations, and the existence of compound mutations in up to 25% of the cases complicate treatment decisions in this patient subgroup. Here, we collate the latest preclinical and clinical data regarding the activity of different TKIs against major uncommon EGFR mutations including compound mutations, but excluding exon 20 insertions which are generally insensitive to TKIs. On the basis of these data, we offer suggestions regarding treatment strategies for uncommon EGFR mutations. Moving forward, it will be important to include uncommon EGFR mutations in the first-line molecular analysis of all patients with adenocarcinoma of the lung, as this will help optimize patient outcomes according to their precise genotype.

Making NSCLC Crystal Clear: How Kinase Structures Revolutionized Lung Cancer Treatment

The parallel advances of different scientific fields provide a contemporary scenario where collaboration is not a differential, but actually a requirement. In this context, crystallography has had a major contribution on the medical sciences, providing a “face” for targets of diseases that previously were known solely by name or sequence. Worldwide, cancer still leads the number of annual deaths, with 9.6 million associated deaths, with a major contribution from lung cancer and its 1.7 million deaths. Since the relationship between cancer and kinases was unraveled, these proteins have been extensively explored and became associated with drugs that later attained blockbuster status. Crystallographic structures of kinases related to lung cancer and their developed and marketed drugs provided insight on their conformation in the absence or presence of small molecules. Notwithstanding, these structures were also of service once the initially highly successful drugs started to lose their effectiveness in the emergence of mutations. This review focuses on a subclassification of lung cancer, non-small cell lung cancer (NSCLC), and major oncogenic driver mutations in kinases, and how crystallographic structures can be used, not only to provide awareness of the function and inhibition of these mutations, but also how these structures can be used in further computational studies aiming at addressing these novel mutations in the field of personalized medicine.

Fluorometric Detection of Low-Abundance EGFR Exon 19 Deletion Mutation Using Tandem Gene Amplification

Epidermal growth factor receptor (EGFR) mutations are not only genetic markers for diagnosis but also biomarkers of clinical-response against tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC). Among the EGFR mutations, the in-frame deletion mutation in EGFR exon 19 kinase domain (EGFR exon 19-del) is the most frequent mutation, accounting for about 45% of EGFR mutations in NSCLCs. Development of sensitive method for detecting the EGFR mutation is highly required to make a better screening for drug-response in the treatment of NSCLC patients. Here, we developed a fluorometric tandem gene amplification assay for sensitive detection of low-abundance EGFR exon 19-del mutant genomic DNA. The method consists of pre-amplification with PCR, thermal cycling of ligation by Taq ligase, and subsequent rolling circle amplification (RCA). PCR-amplified DNA from genomic DNA samples was used as splint DNA to conjugate both ends of linear padlock DNA, generating circular padlock DNA template for RCA. Long stretches of ssDNA harboring multiple copies of G-quadruplex structure was generated in RCA and detected by thioflavin T (ThT) fluorescence, which is specifically intercalated into the G-quadruplex, emitting strong fluorescence. Sensitivity of tandem gene amplification assay for detection of the EGFR exon 19-del from gDNA was as low as 3.6 pg, and mutant gDNA present in the pooled normal plasma was readily detected as low as 1% fraction. Hence, fluorometric detection of low-abundance EGFR exon 19 deletion mutation using tandem gene amplification may be applicable to clinical diagnosis of NSCLC patients with appropriate TKI treatment.