19del Mutation Research Articles

Advanced lung adenocarcinoma with EGFR 19-del mutation transforms into squamous cell carcinoma after EGFR tyrosine kinase inhibitor treatment

In this editorial we comment on the article by Ji et al . We focus specifically on the EGFR tyrosine kinase inhibitor (EGFR-TKI) treatment and the development of drug resistance to EGFR-TKIs.

Clinical characteristics and prognostic factors of epidermal growth factor receptor-mutated non-small cell lung cancer transformed into small-cell lung cancer after treatment

Objective: To analyze the clinical characteristics and prognostic factors of non-small cell lung cancer (NSCLC) patients with sensitive epidermal growth factor receptor (EGFR) mutations who developed small cell lung cancer (SCLC) transformation after treatment with EGFR tyrosine kinase inhibitors (TKI). Methods: We conducted a retrospective collection of clinical data for 21 patients with advanced EGFR mutant NSCLC who developed SCLC transformation after EGFR-TKI treatment at Beijing Chest Hospital, Capital Medical University from January 2015 to December 2021. The clinical characteristics were summarized and the prognosis analysis was conducted. Patients were followed up until February 2024. The efficacy was evaluated using Solid Tumor Response Evaluation Criteria, and survival curves were plotted using the Kaplan-Meier method, and the log-rank test was used to compare the differences in survival time (OS) between limited stage and extensive stage in transformed SCLC patients. Cox proportional hazards model was used to analyze the influencing factors of survival after SCLC transformation. Results: Among the 21 patients, there were 5 males and 16 females, with an age range of 33-74 years old [(58.9±2.6) years old]. All 21 patients were adenocarcinoma with sensitive EGFR mutations. There were 18 cases (85.7%) with EGFR gene 19del mutation, including 1 case of 19del+anaplastic lymphoma kinase (ALK) mutation, and 3 cases of L858R mutation. Among the transformed SCLC, there were 11 cases of pure SCLC and 10 cases of mixed SCLC (coexisting of adenocarcinoma and small cell carcinoma components). The median time from diagnosis of NSCLC to SCLC transformation was 12.0 months (95%CI: 7.6-16.3 months). Among the 21 cases of SCLC transformation, there were 13 cases with the extensive stage and 8 cases with the limited stage. Among them, 16 patients received systemic chemotherapy based on etoposide, of which 13 cases could be evaluated for efficacy, 11 cases could be calculated for PFS. Five cases had partial remission, 5 cases were stable, 3 cases had disease progression, and 3 cases cloud not be evaluated. The median progression free survival time (PFS) was 4.8 months (95%CI: 2.8-6.8 months). The median survival time (OS) after SCLC transformation in 21 patients was 10.6 months (95%CI: 7.0-14.2 months), with a median OS of 8.8 months (95%CI: 6.3-11.4 months) for patients with the extensive stage and 27.5 months (95%CI: 9.6-34.4 months) for patients with the limited stage, with statistically significant differences (P=0.002). Cox proportional hazards model analysis showed that the limited stage after SCLC transformation was a protective factor for OS (HR=0.32, 95%CI: 0.12-0.73, P=0.010). The median OS of 21 patients from the diagnosis of lung cancer was 24.9 months (95%CI: 13.0-36.7 months). Conclusions: NSCLC patients with SCLC transformation are all adenocarcinomas, and the proportion of EGFR19del mutations is relatively high. After SCLC transformation, the standard chemotherapy regimen for SCLC is generally used for treatment. The OS after SCLC transformation is related to the stage, and the prognosis is better in the limited stage.

FLAIR: A Phase II, Open Label, Randomized Study of Osimertinib Plus Bevacizumab Versus Osimertinib in Recurrent or Metastatic Treatment-Naïve NSCLC Patients Harboring EGFR 21L858R Mutation

IntroductionOsimertinib, the 3rd generation EGFR-TKI, has emerged as standard first-line treatment for patients with advanced EGFR mutated nonsmall cell lung cancer (NSCLC). Patients with exon 21 L858R mutation showed lower efficacy with EGFR-TKIs than those with 19Del mutation, even with osimertinib, it remains an unmet medical need to further improve the efficacy in L858R population. We present the rationale and design for FLAIR (NCT04988607), which will investigate the efficacy and safety of osimertinib plus bevacizumab versus osimertinib monotherapy in treatment-naïve recurrent or metastatic NSCLC patients harboring EGFR exon 21 L858R mutation. Materials and MethodsFLAIR is a prospective, multicenter, randomized, open label study, which is initiated by Chinese Thoracic Oncology Group (CTONG2002). Patients age ≥18 years with primary recurrent or metastatic nonsquamous NSCLC who are treatment-naïve with documented EGFR exon 21 L858R mutation is eligible. Patients will be randomized 1:1 to receive osimertinib 80 mg once daily plus bevacizumab 15mg/kg every 3 weeks or osimertinib monotherapy 80 mg once daily until progression or another discontinuation criterion is met. The primary endpoint is investigator-assessed progression free survival (PFS). Secondary endpoints include: overall survival rate at 24 months, time to treatment failure (TTF), overall response rate (ORR), disease control rate (DCR), duration of response (DoR), central nervous system (CNS) PFS, CNS ORR and safety. ResultsFLAIR has completed the enrollment, and results are expected in the fourth quarter of 2025 (depending on the actual event rate). ConclusionsThis study will offer better perspectives on the efficacy and safety of osimertinib plus bevacizumab combination therapy in treatment-naïve recurrent or metastatic NSCLC patients harboring EGFR exon 21 L858R mutation, providing valuable guidance for clinical practice.

Phase III KEYNOTE-789 Study of Pemetrexed and Platinum With or Without Pembrolizumab for Tyrosine Kinase Inhibitor‒Resistant, EGFR-Mutant, Metastatic Nonsquamous Non-Small Cell Lung Cancer.

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are standard first-line therapy for EGFR-mutant, metastatic non-small cell lung cancer (NSCLC); however, most patients experience disease progression. We report results from the randomized, double-blind, phase III KEYNOTE-789 study of pemetrexed and platinum-based chemotherapy with or without pembrolizumab for TKI-resistant, EGFR-mutant, metastatic nonsquamous NSCLC (ClinicalTrials.gov identifier: NCT03515837). Adults with pathologically confirmed stage IV nonsquamous NSCLC, documented DEL19 or L858R EGFR mutation, and progression after EGFR-TKI treatment were randomly assigned 1:1 to 35 cycles of pembrolizumab 200 mg or placebo once every 3 weeks plus four cycles of pemetrexed and carboplatin or cisplatin once every 3 weeks and then maintenance pemetrexed. Dual primary end points were progression-free survival (PFS) and overall survival (OS). Final PFS testing was completed at the second interim analysis (IA2; data cutoff, December 3, 2021); OS was tested at final analysis (FA; data cutoff, January 17, 2023). Efficacy boundaries were one-sided P = .0117 for PFS and OS. Four hundred ninety-two patients were randomly assigned to pembrolizumab plus chemotherapy (n = 245) or placebo plus chemotherapy (n = 247). At IA2, the median PFS was 5.6 months for pembrolizumab plus chemotherapy versus 5.5 months for placebo plus chemotherapy (hazard ratio [HR], 0.80 [95% CI, 0.65 to 0.97]; P = .0122). At FA, the median OS was 15.9 versus 14.7 months, respectively (HR, 0.84 [95% CI, 0.69 to 1.02]; P = .0362). Grade ≥3 treatment-related adverse events occurred in 43.7% of pembrolizumab plus chemotherapy recipients versus 38.6% of placebo plus chemotherapy recipients. Addition of pembrolizumab to chemotherapy in patients with TKI-resistant, EGFR-mutant, metastatic nonsquamous NSCLC did not significantly prolong PFS or OS versus placebo plus chemotherapy in KEYNOTE-789.

Benefits of osimertinib treat a lung adenocarcinoma patient with germline EGFR T790M, somatic EGFR 19-Del, TP53 and PIK3CA mutations

BackgroundSomatic mutations in the EGFR gene occur in about 50% of non-small cell lung cancers, with the T790M mutation significantly contributing to secondary resistance against EGFR-TKI drugs. However, EGFR T790M germline mutations rarely occur.Case presentationIn this study, we report a case of a lung adenocarcinoma family lineage linked to a germline EGFR T790M mutation. The main subject was diagnosed with stage IV lung adenocarcinoma and experienced a 19-month period without disease progression while treated with Osimertinib. We collected both clinicopathological and familial data from a patient with lung adenocarcinoma. Next-generation sequencing of 40 key genes was performed on the proband’s tumor tissue. To detect EGFR germline mutations, Sanger sequencing was conducted on peripheral blood mononuclear cells from the proband and his two daughters. Mutations such as EGFR T790M, EGFR 19-Del, TP53, and PIK3CA were identified in the proband’s lung cancer tissue. Additionally, germline EGFR T790M mutations were confirmed in the proband and his daughters through sequencing of their peripheral blood samples. CT scans revealed multiple pulmonary nodules in both daughters.ConclusionsThese observations suggest that germline mutations in EGFR T790M could be strongly linked to a familial predisposition to lung cancer.

EHSP90α in front-line therapy in EGFR exon 19 deletion and 21 Leu858Arg mutations in advanced lung adenocarcinoma

PurposeExtracellular heat shock protein 90 AA1(eHSP90α) is intricately linked to tumor progression and prognosis. This study aimed to investigate the difference in the value of eHSP90α in post-treatment response assessment and prognosis prediction between exon 19 deletion(19DEL) and exon 21 Leu858Arg(L858R) mutation types in lung adenocarcinoma(LUAD).MethodsWe analyzed the relationship between the expression of eHSP90α and clinicopathological features in 89 patients with L858R mutation and 196 patients with 19DEL mutation in LUAD. The Kaplan-Meier survival curve was used to determine their respective cut-off values and analyze the relationship between eHSP90α expression and the survival time of the two mutation types. The area under the curve (AUC) was used to evaluate the diagnostic performance of biomarkers. Then, the prognostic model was developed using the univariate-Cox multivariate-Cox and LASSO-multivariate logistic methods.ResultsIn LUAD patients, eHSP90α was positively correlated with carcinoembryonic antigen(CEA), carbohydrate antigen 125(CA125), and carbohydrate antigen 153(CA153). The truncated values of eHSP90α in L858R and 19DEL patients were 44.5 ng/mL and 40.8 ng/mL, respectively. Among L858R patients, eHSP90α had the best diagnostic performance (AUC = 0.765), and higher eHSP90α and T helper cells(Th cells) expression were significantly related to shorter overall survival(OS) and worse treatment response. Also, high eHSP90a expression and short progression-free survival(PFS) were significantly correlated. Among 19DEL patients, CEA had the best diagnostic efficacy (AUC = 0.734), and CEA and Th cells were independent prognostic factors that predicted shorter OS. Furthermore, high CA125 was significantly associated with short PFS and poor curative effect.ConclusionseHSP90α has a better prognostic value in LUAD L858R patients than 19DEL, which provides a new idea for clinical diagnosis and treatment.

The current landscape, advancements, and prospects in the treatment of patients with EGFR exon 20 insertion mutations warrant scientific elucidation.

Epidermal growth factor receptor (EGFR) exon 20 insertion (ex20ins) mutations are the third most prevalent mutation in non-small cell lung cancer (NSCLC), following the 19del and L858R mutations. The unique nature of the EGFR ex20ins mutation poses challenges for the effectiveness of first- and second-generation EGFR tyrosine kinase inhibitors (TKIs). As a result, chemotherapy remains the primary and more effective treatment approach. However, with advancements in time and technology, numerous experimental studies have revealed the potential of novel drugs and therapies to have stronger inhibitory effects on EGFR ex20ins mutations. In this comprehensive review, we provide an overview of the current treatment landscape, recent advancements, and the prospects for patients with advanced NSCLC characterized by EGFR ex20ins mutations.

Exploring the Cause of Survival Disparities in EGFR-Mutated Lung Cancer Subtypes: Unraveling Distinctive Genomic and Phenotypic Features of 19Del and L858R Mutation Subtypes

Exploring the Cause of Survival Disparities in EGFR-Mutated Lung Cancer Subtypes: Unraveling Distinctive Genomic and Phenotypic Features of 19Del and L858R Mutation Subtypes

Real-world clinical outcomes in Chinese patients with EGFR-mutated NSCLC progressed from first-line EGFR-TKI: A prospective multicenter study.

e20547 Background: EGFR-TKIs is standard of care for treatment-naïve EGFR mutated ( EGFRm) advanced NSCLC (aNSCLC). The clinical outcome after 1L EGFR-TKI in clinical practice is not well studied prospectively. Herein, we reported the real-world clinical outcomes in Chinese EGFRm aNSCLC progressed from 1L EGFR-TKI. Methods: This prospective, observational study enrolled 300 Chinese patients (pts) from 16 sites between March, 2020 and August, 2021. At data cut-off date of August 27, 2023. 291 eligible pts were included into the full analysis set (FAS) and 225 pts in FAS received second-line EGFR-TKI or chemotherapy were included into outcome analysis set (OAS). The clinical outcome (PFS and OS, measured from 2nd line treatment) were presented. Results: The median age of 291 pts in FAS was 62 years, 57.0% was females and 29.3% pts with brain metastasis. EGFR mutation included 19del (143 pts, 49.1%), L858R (126 pts, 43.3%) and others (22 pts, 7.6%). 273 (93.8%) and 18 (6.2%) pts progressed from 1L 1G/2G EGFR-TKIs and 3G EGFR-TKIs, respectively. In OAS, overall mPFS and mOS in T790M + patients (90 pts) who received 2L 3G EGFR-TKIs were 14.7 (10.40-18.0) and 32 (25.20-NE) months, respectively. The mPFS and mOS by type of sample and T790M test results were presented in table. 85 pts with T790M- who progressed from 1L 1/2G EGFR-TKIs, including 51, 9 and 25 pts received 3G EGFR-TKIs, prior EGFR-TKIs plus local therapy, and chemotherapy as 2L therapy, respectively. The corresponding mPFS were 7.60 (95% CI, 4.70-10.40), 10.20 (2.30-14.90), and 4.90 (2.50-6.90) months, respectively. The corresponding mOS were 21.20 (12.10-NE), 16.60 (6.00-28.60), and 15.00 (9.40-NE) months, respectively. For T790M- patients with 19del (21 pts) and L858R (26 pts) mutation who received 2L 3G EGFR-TKIs, the mPFS was 21.00 (2.60-NE), and 8.00 (5.00-10.40) months, respectively. mOS was NE (21.00-NE) and 16.60 (8.20-24.60) months, respectively. 12 pts progressed from 1L 3G EGFR-TKIs, 10 and 2 pts received chemotherapy-based regimen and prior EGFR-TKIs plus local therapy as 2L therapy, respectively. The corresponding overall mPFS were 8.40 (95% CI: 1.20-11.80) months. The overall mOS was 14.20 (2.80-NE) months. Conclusions: The real-world treatment pattern and corresponding prognosis of EGFR-mutated NSCLC progressed from first-line EGFR-TKI were diverse, and among them those who received 3G EGFR-TKI at progression showed a better clinical outcome. These results supplemented the clinical evidence for the use of 3G EGFR-TKIs in EGFRm aNSCLC pts who progressed from 1L 1/2G EGFR-TKIs in the real-world setting. Clinical trial information: NCT04207775 . [Table: see text]

Safety and efficacy of osimertinib plus bevacizumab as first-line treatment in EGFR-mutant NSCLC with brain metastases: A dynamic ctDNA-guided study.

e20606 Background: Non-small cell lung cancer (NSCLC) patients with positive driver genes had a higher incidence of brain metastasis. This study evaluates the efficacy and safety of Osimertinib combined with Bevacizumab as first line treatment in EGFR-mutant NSCLC with brain metastases, utilizing liquid biopsy and dynamic molecular detection to guide treatment strategies. This approach is anticipated to bring progression-free survival (PFS) benefits and shows different resistant mechanisms. Methods: We enrolled EGFR-mutant NSCLC patients with brain metastases receiving Osimertinib and Bevacizumab as first-line therapy. Paired plasma and cerebrospinal fluid (CSF) samples were collected at baseline, during stable disease, and at disease progression for Next-Generation Sequencing (NGS) analysis. The study's primary endpoints were central nervous system (CNS) PFS and objective response rate (ORR). Secondary endpoints included overall PFS, ORR, disease control rate (DCR), and safety. We also investigated resistance mechanisms to the combination therapy. Results: A total of 28 patients from Beijing TianTan Hospital (May 2020 - July 2023) were retrospectively enrolled. The average Bevacizumab treatment duration was 8.21 months (range: 1-27 months). CNS PFS was 26.73 months (95% CI, not reached), and overall PFS was 21.93 months (95% CI, 18.84-25.02 months). The CNS PFS for patients with 19del and L858R mutations were not reached and 26.73 months (95% CI, 15.11-38.35 months), respectively (p = 0.25). Patients undergoing intracranial local treatment showed a CNS PFS not reached, compared to 23.33 months (95% CI, 16.21-30.45 months) for those who did not (p = 0.417). The CNS ORR was 88%, ORR was 76%, and DCR was 100%. At the time of data cutoff (Dec 15th, 2023), 1 patient progressed in both lung and CNS metastases, 8 patients only progressed in lung, 8 patients only progressed in CNS metastases .EGFR C797S mutation was detected in 2 plasma sample, Met amplification in 1 tumor tissue, EGFR C719S mutation in 1 paired plasma-tumor tissue and PIK3CA in 2 plasma sample. Increasing abundance in TP53 and CDKN2A were detected in 2 paired plasma-tumor tissue. Adverse events of grade 3 or higher included one case (3.6%) of severe ulcerative colitis leading to Osimertinib discontinuation and two cases (7.1%) of bevacizumab discontinuation due to bleeding events. Conclusions: Osimertinib combined with Bevacizumab as a first-line treatment significantly prolonged CNS PFS in EGFR-mutant NSCLC patients with brain metastases, offering superior control over intracranial lesions compared to Osimertinib monotherapy (15.2 months, FLAURA study). This study underscores the potential of dynamic ctDNA monitoring in guiding effective treatment strategies for this patient population. Further research is warranted to explore the broader clinical implications of these findings.

Elucidating the role of RBM10 in brain metastasis of EGFR19del lung adenocarcinoma.

e20501 Background: The EGFR mutation was detected in 66.3% of Asian patients with lung adenocarcinoma. Among these mutations, EGFR 19del exhibited the highest sensitivity and best response. However, it is worth noting that patients with EGFR 19del have a high cumulative incidence of brain metastases, which contributes significantly to treatment failure. Based on previous WES analysis of primary lung cancer cases and their corresponding brain metastases, RBM10 co-mutation was observed in four out of ten cases with EGFR 19del mutation, leading to decreased expression levels of RBM10. These findings suggest a potential role for RBM10 in modulating the development of brain metastases in patients with EGFR 19del lung cancer. Methods: To investigate the role of RBM10 in brain metastasis, we performed RNA-seq on the PC9 cell line to identify metabolic pathways and genes associated with RBM10 and brain metastasis. Additionally, the brain metastasis model was established by injecting PC9 cells into the left ventricle of nude mice, and the ability of PC9 cells to form brain metastases after knocking down RBM10 was confirmed through two rounds of in vivo screening using the PC9 cell line. Lipidomics analysis further validated that RBM10 affects key metabolite production. Clip-seq and RNA-seq were employed to analyze how RBM10 regulates sphingolipid metabolism. Finally, we identified key targets affecting blood-brain barrier function within the sphingolipid metabolism pathway and verified their ability to inhibit brain metastasis using both in vitro and in vivo models. Results: RNA-seq results demonstrated the regulatory role of RBM10 in the sphingolipid metabolism pathway, specifically in GALC regulation. In vitro and in vivo models revealed an enhanced brain metastasis ability of the PC9shRBM10 group. Lipidomics analysis revealed that the knockdown of RBM10 resulted in a reduction in ceramide and an elevation in SPH. Integrated RNA-seq and Clip-seq analyses demonstrated that the splicing regulation on GALC was attenuated upon RBM10 knockdown, leading to an increase in GALC expression. Furthermore, this perturbation enhanced the downstream sphingosine-1-phosphate signalling axis (SPH-SK1/2-S1P), consequently promoting increased S1P production and elevated blood-brain barrier permeability. Finally, fingolimod, an S1P inhibitor, was employed to validate its efficacy in inhibiting brain metastasis; moreover, a combination therapy comprising osimertinib and fingolimod exhibited superior capacity for suppressing brain metastasis. Conclusions: This study aims to elucidate the regulatory mechanism underlying the impact of RBM10 on sphingolipid metabolism in brain metastasis of EGFR 19del lung adenocarcinoma, to identify novel therapeutic targets for preventing brain metastasis in patients exhibiting EGFR 19del lung adenocarcinoma with low RBM10 expression.

CLINICAL FACTORS PREDECTING T790M MUTATION IN NON-SMALL CELL LUNG CANCER PROGRESSED AFTER FIRST- AND SECOND-GENERATION TKI TREATMENT

Objective: We aimed to identify the T790M mutation rate and clinical factors predicting the occurrence of acquired T790M mutations in advanced non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations after first- and second-generation tyrosine kinase inhibitor (TKI) treatment. Method: The EGFR-mutant NSCLC patients who experienced progression after first- and second-generation TKI treatment and underwent testing for EGFR using plasma samples between January 2021 and April 2023 were enrolled. The T90M mutation rate and related clinical factors were evaluated. We utilized the Chi-square test or Fisher’s exact test for univariate analysis and multivariable logistic binary regression for multivariate analysis. Results: A total of 247 patients were eligible for the study. Patients harbored the exon 19 deletion mutation (Del19), exon 21 L858R point mutation, and uncommon mutations in 63.2%, 34.4%, and 2.4% of cases, respectively. The overall T790M mutation rate was 33.6%. In multivariate analyses, the Del19 mutation versus L858R mutation, duration of first-line TKI exceeding 12 months versus below 12 months, and solitary lesion progression versus multiple lesion progression were identified as favorable prognostic factors for the occurrence of T790M mutation. Conclusion: Patients with EGFR exon 19 deletion, a prolonged treatment duration of first-line EGFR-TKI, and solitary lesion progression pattern are more likely to acquire the T790M mutation, as detected by the PCR method in plasma samples.

Prognostic implications of combining EGFR-TKIs and radiotherapy in Stage IV lung adenocarcinoma with 19-Del or 21-L858R mutations: A real-world study.

To elucidate the potential benefits of combining radiotherapy and epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) for individuals with Stage IV lung adenocarcinoma (LUAD) harboring either exon 19 deletion (19-Del) or exon 21 L858R mutation (21-L858R). In this real-world retrospective study, 177 individuals with Stage IV LUAD who underwent EGFR-TKIs and radiotherapy at Shandong Cancer Hospital from June 2012 to August 2017 were included. The main focus of this real-world study was overall survival (OS). The clinical characteristics of patients with Stage IV LUAD harboring 19-Del were similar to those harboring 21-L858R (p > 0.05). Overall, the patients had a median OS (mOS) of 32.0 months (95% confidence interval [CI]: 28.6-35.5). Subsequently, multivariate analysis indicated that both EGFR mutations and thoracic radiotherapy were independent predictors of OS (p = 0.001 and 0.013). Furthermore, subgroup analysis highlighted a longer OS for the 19-Del group compared to the 21-L858R group, especially when EGFR-TKIs were combined with bone metastasis or thoracic radiotherapy (mOS: 34.7 vs. 25.1 months and 51.0 vs. 29.6 months; p = 0.0056 and 0.0013, respectively). However, no significant differences were found in OS when considering patients who underwent brain metastasis radiotherapy (mOS: 34.7 vs. 25.1 months; p = 0.088). Patients with Stage IV LUAD harboring 19-Del experience a notably prolonged OS following combined therapy with EGFR-TKIs and radiotherapy, while this OS benefit is observed despite the absence of substantial differences in the clinical characteristics between the 19-Del and 21-L858R groups.

Distinguishing EGFR mutation molecular subtypes based on MRI radiomics features of lung adenocarcinoma brain metastases

ObjectiveTo explore the feasibility of identifying epidermal growth factor receptor (EGFR) mutation molecular subtypes in primary lesions based on the radiomics features of lung adenocarcinoma brain metastases using magnetic resonance imaging (MRI). MethodsWe retrospectively analyzed clinical, imaging, and genetic testing data of patients with lung adenocarcinoma with EGFR gene mutations who had brain metastases. Three-dimensional radiomics features were extracted from contrast-enhanced T1-weighted images. The volume of interest was delineated and normalized using Z-score, dimensionality reduction was performed using principal component analysis, feature selection using Relief, and radiomics model construction using adaptive boosting as a classifier. Data were randomly divided into training and testing datasets at an 8:2 ratio. Five-fold cross-validation was conducted in the training set to select the optimal radiomics features and establish a predictive model for distinguishing between exon 19 deletion (19Del) and exon 21 L858R point mutation (21L858R), the two most common EGFR gene mutations. The testing set was used for external validation of the models. Model performance was evaluated using receiver operating characteristic curve and decision curve analyses. ResultsOverall, 86 patients with 228 brain metastases were included. Patient age was identified as an independent predictor for distinguishing between 19Del and 21L858R. The area under the curve (AUC) values of the radiomics model in the training and testing datasets were 0.895 (95% confidence interval [CI]: 0.850−0.939) and 0.759 (95% CI: 0.0.614−0.903), respectively. The AUC for diagnosis of all cases using a combined model of age and radiomics was 0.888 (95% CI: 0.846−0.930), slightly higher than that of the radiomics model alone (0.866, 95% CI: 0.820−0.913), but without statistical significance (p=0.1626). In the decision curve analysis, both models demonstrated clinical net benefits. ConclusionsThe radiomics model based on MRI of lung adenocarcinoma brain metastases could distinguish between EGFR 19Del and 21L858R mutations in the primary lesion.

Abstract 5774: Are 19del and L858R really not the same disease entities

Abstract IntroductionThe similarities and differences between the two subtypes of common epidermal growth factor receptor (EGFR) mutations have been recognized by clinicians, but actual treatment strategies remain unchanged. The L858R mutation can be explained by the pharmacological conformational plasticity of the receptor protein and other co-occurring mutations, which may be subtypes of EGFR mutations or non-EGFR mutations, and differences in downstream signaling pathways. As long as we know that molecular differences lead to biological differences, it is a challenge for all of us that our treatment strategies must changeWe investigated the RWD, conformational structure and RNA expression profile about two types of common mutations in the mEGFR+ NSCLC patients.MethodWe collected the medical information for stage I-IIIA mEGFR+ NSCLC patients and explored the conformational structure by crystalized radiologic technique. And we performed RNA expression assay using multiplex IF and High-through-output Profiling. ResultOverall, the static structures of wild type (WT), L858R, and 19del (ΔL747-E749) EGFR did not show any significant differences. However, the difference in the static structure between WT-19del and L858R-19del was subtly greater than that of WT-L858R. In addition, further analyses demonstrated no significant structural differences in the phosphorylation sites. However, it should be noted that proteins do not exist as static structures in vivo, and they have a dynamic, flexible structure that changes over time, i.e., plasticity of proteins. Therefore, we investigated the X-ray B-factor value, which is an indicator of flexibility, dynamics, and plasticity of proteins. As expected, the loop or disordered regions mainly shows higher B-factor values, which indicates an active structure, highly changeable and dynamic. Together, the three types of the EGFR protein manifest wholly similar B-factor values, while several local regions present appreciably distinct B-factors. Physical properties such as the dynamic structure may affect intermolecular recognition of EGFR proteins and their function Recent biochemical and biophysical evidence suggests that oncogenic mutations have an impact on the conformational dynamics of enzymesConclusionIn conclusion, our results suggest that Patients with 19del and L858R mutations demonstrated a different clinical course. It is necessary to consider the dynamic structural characteristics and functional differences of EGFR membrane proteins. Citation Format: Yunseok Heo, Joo Ri Kim, Yeoun Eun Sung, Seoree Kim, Chan Kwon Jung, Jeong-Oh Kim, Jeong-yeon Shin, Guk Jin Lee, Sang hoon Chun, Seong Hyeon Bu, Young Ho Lee, Jin Hyoung Kang. Are 19del and L858R really not the same disease entities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5774.

Abstract 964: Updated results of a prospective observational multicenter study on resistance mechanisms to osimertinib using circulating tumor DNA analyses in EGFR-mutated non-small cell lung cancer patients (ELUCIDATOR study)

Abstract Background: Although osimertinib (Osi) is the key standard therapy for patients (pts) with advanced non-small cell lung cancer (NSCLC) harboring sensitizing epidermal growth factor receptor (EGFR) mutations, most of cases experience the progressive disease (PD) after initial response to the treatment. Therefore, understanding the Osi resistance mechanisms and identifying the poor responders are essential to develop better treatment strategies. Thus, we conducted a prospective observational multicenter study and analyzed serially collected circulating tumor DNA (ctDNA). Here we report the results from updated analyses focusing on the association between genetic information from ctDNA and clinical outcome. Methods: Patient eligibility criteria were as follows: a definitive diagnosis of non-squamous NSCLC confirmed through biopsy or cytology, EGFR exon 19 deletion (19del) or L858R mutation, Osi planned as first-line treatment, and pts who could provide blood specimens. Paired plasma DNA samples were collected before starting Osi as baseline (BL) and at PD and analyzed to investigate Osi resistance by next-generation sequencing (NGS). Correlations between genetic information obtained from ctDNA and clinical outcome such as progression free survival (PFS) and overall survival (OS) were evaluated. The median follow-up time was 33.1 months. Results: One hundred eighty-eight pts were enrolled between May 2019 and January 2021, and 125 (66%) were female, 96 (51%) were EGFR 19del mutation, and 109 (58%) were never smoker. Among those, 178 pts were included in the analyses, and 111 experienced PD. In consistent with previous reports, median PFS (mPFS) and median OS (mOS) were 19.1 months and 36.0 months, respectively. The efficacy of Osi differed between 19del and L858R in both PFS and OS, with 19del being longer outcome [mPFS, 23.3 months vs. 17.2 months, HR: 1.56 (95%CI: 1.08-2.26), mOS, 40.3 months vs. 30.4 months, HR: 1.54 (95%CI: 0.98-2.45)]. Univariate analysis revealed that the presence of TP53 mutations and MET amplification (amp) at BL was a predictive factor of shorter PFS and OS. Multivariate analysis also revealed that the TP53 mutations at BL was a predictive factor of shorter PFS and OS. Plasma samples from 85 pts were available for ctDNA analysis. New adaptive mutations or amp at PD were detected in genes such as PIK3CA in 3 cases, MET amp in 4, TP53 in 4, BRIMP3 in 2, APC in 1, and BRAF in 2. Secondary EGFR C797S resistance mutation was detected in 1 case. Conclusions: TP53 mutation at BL could be predictive of poor response to Osi. MET amp and PIK3CA mutations were detected as the most common resistance mechanisms, and secondary EGFR resistance mutations were observed less frequently than previous reports. Citation Format: Mitsuo Osuga, Akihiro Tamiya, Daijiro Harada, Yasuyuki Mizumori, Shun-ichi Isa, Yoshihiko Taniguchi, Keiichi Nakamura, Tsutomu Shinohara, Hidetoshi Yanai, Katsumi Nakatomi, Masahide Oki, Masahide Mori, Tomohito Kuwako, Koji Yamazaki, Atsuhisa Tamura, Masahiko Ando, Yasuhiro Koh. Updated results of a prospective observational multicenter study on resistance mechanisms to osimertinib using circulating tumor DNA analyses in EGFR-mutated non-small cell lung cancer patients (ELUCIDATOR study) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 964.

A real-world cohort study of first-line afatinib in patients with EGFR-mutant advanced non-small cell lung cancer in Vietnam

BackgroundThis study aimed to evaluate the efficacy and side effects of first-line afatinib treatment in a real-world setting in Vietnam.MethodsThis retrospective study was conducted across nine hospitals in Vietnam. Advanced epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) patients who received afatinib as first-line therapy between April 2018 and June 2022 were included, and patient medical records were reviewed. Key outcomes were overall response rate (ORR), time-to-treatment failure (TTF), and tolerability.ResultsA total of 343 patients on first-line afatinib were eligible for the study. EGFR exon 19 deletion (Del19) alone was detected in 46.9% of patients, L858R mutation alone in 26.3%, and other uncommon EGFR mutations, including compound mutations, in 26.8%. Patients with brain metastases at baseline were 25.4%. Patients who received 40 mg, 30 mg, and 20 mg as starting doses of afatinib were 58.6%, 39.9%, and 1.5%, respectively. The ORR was 78.1% in the overall population, 82.6% in the Del19 mutation subgroup, 73.3% in the L858R mutation subgroup, and 75.0% in the uncommon mutation subgroup (p > 0.05). The univariate and multivariate analyses indicate that the ORR increased when the starting dose was 40 mg compared to starting doses below 40 mg (83.9% vs. 74.3%, p = 0.034). The median TTF (mTTF) was 16.7 months (CI 95%: 14.8–18.5) in all patients, with a median follow-up time of 26.2 months. The mTTF was longer in patients in the common EGFR mutation subgroup (Del19/L858R) than in those in the uncommon mutation subgroup (17.5 vs. 13.8 months, p = 0.045) and in those without versus with brain metastases at baseline (17.5 vs. 15.1 months, p = 0.049). There were no significant differences in the mTTF between subgroups based on the starting dose of 40 mg and < 40 mg (16.7 vs. 16.9 months, p > 0.05). The most common treatment-related adverse events (any grade/grade ≥ 3) were diarrhea (55.4%/3.5%), rash (51.9%/3.2%), paronychia (35.3%/5.0%), and stomatitis (22.2%/1.2%).ConclusionsAfatinib demonstrated clinical effectiveness and good tolerability in Vietnamese EGFR-mutant NSCLC patients. In our real-world setting, administering a starting dose below 40 mg might result in a reduction in ORR; however, it might not have a significant impact on TTF.

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

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. 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. 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). 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.

Primary versus acquired epidermal growth factor receptor Thr790Met mutant non-small cell lung cancer: clinical features and prognoses.

This study aimed to identify the impact of epidermal growth factor receptor (EGFR) T790M mutations on clinical characteristics and prognosis. Retrospective analyses were conducted on the differences on clinicopathological features and prognosis between primary and acquired T790M mutations. Subgroup analyses were performed for primary T790M coexisting with othermutations. Patients with primary T790M mutations showed a 60.53% (23/38) incidence of concurrent L858R mutations, 18.42% (7/38) for 19del mutations and a 21.05% (8/38) occurrence of brain metastases. Conversely, those with acquired T790M mutations demonstrated respective frequencies of 36.53% (61/167), 58.68% (98/167) and 44.31% (74/167), with all comparisons yielding p < 0.05. The median overall survival differed significantly between the two groups, with a duration of 33months for patients with primary T790M mutations as compared to 48months for those with acquired mutations (p = 0.030). Notably, among patients with L858R co-mutations, when treated with third-generation EGFR-TKIs, those with acquired T790M mutations experienced a significantly prolonged median time to treatment failure compared to those with primary mutations (17months vs. 9months, p = 0.009). Patients with primary T790M have unique molecular features and had worse prognosis compared with acquired T790M. Resistance to third-generation EGFR-TKIs seems to be associated with the presence of EGFR co-mutations.

Silencing of lncRNA LOC105376794 promotes migration, invasion, and Gefitinib resistance of lung adenocarcinoma cells with EGFR 19Del mutation by ATF4/CHOP axis and ERK phosphorylation.

Epidermal growth factor receptor (EGFR) gene exon 19 in-frame deletion (19del) and exon 21 L858R point mutation (21L858R mutation) are prevalent mutations in lung adenocarcinoma. Lung adenocarcinoma patients with 19del presented with a better prognosis than the 21L858R mutation under the same epidermal growth factor receptor tyrosine kinase inhibitor treatment. Our study aimed to uncover the expression of long non-coding RNA LOC105376794 between 19del and 21L858R mutation, and explore the mechanism that regulates cells' biological behavior and gefitinib sensitivity in lung adenocarcinoma cells with 19del. Transcriptome sequencing was conducted to identify differentially expressed lncRNAs between EGFR 19del and 21L858R mutation in serum through the DNBSEQ Platform. Protein-protein interaction network and Kyoto Encyclopedia of Genes and Genomes pathway were conducted to analyze the relationship between lncRNAs and mRNAs through STRING and Dr. TOM. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to measure the expression of lncRNA LOC105376794 in serum and cells. Loss-of-function experiments were used to validate the biological function and gefitinib sensitivity of LOC105376794 in lung adenocarcinoma cells. Protein levels were detected by western blotting. Through transcriptome resequencing and RT-qPCR, we found the expression levels of LOC105376794 in serum were increased in the 19del group compared with the 21L858R mutation group. Inhibition of LOC105376794 promoted proliferation, migration and invasion, and reduced apoptosis of HCC827 and PC-9 cells. The low expression of LOC105376794 reduced gefitinib sensitivity in PC-9 cells. Mechanistically, we found that the knockdown of LOC105376794 suppressed activating transcription factor 4 (ATF4)/C/EBP homologous protein (CHOP) signaling pathway and facilitated the expression of extracellular signal-regulated kinase 1/2 (ERK) phosphorylation. LOC105376794 altered cell biological behavior and gefitinib sensitivity of lung adenocarcinoma cells with 19del through the ATF4/CHOP signaling pathway and the expression of ERK phosphorylation. The results further illustrated the fact that lung adenocarcinoma patients with 19del presented with a more favorable clinical outcome and provided a theoretical basis for treatment strategy for lung adenocarcinoma patients with 19del.