Rare EGFR Mutations Research Articles

Almonertinib and alflutinib show novel inhibition on rare EGFR S768I mutant cells.

EGFR classical mutations respond well to EGFR tyrosine kinase inhibitors. However, it is uncertain whether currently available EGFR-TKIs are effective against rare EGFR mutations and compound mutations. Herein, the effectiveness of almonertinib and alflutinib, the third-generation tyrosine kinase inhibitors developed in China, on rare EGFR S768I mutations and compound mutations is identified. In this study, using CRISPR method, four EGFR S768I mutation cell lines were constructed, and the sensitivity of EGFR to almonertinib and alflutinib was tested, with positive controls being the 1st (gefitinib), 2nd (afatinib), and 3rd (osimertinib) generation drugs. The present results indicate that almonertinib and alflutinib can effectively inhibit cell viability and proliferation in rare EGFR S768I mutations through the ERK or AKT pathways in a time-dependent manner, by blocking the cell cycle and inhibiting apoptosis. These findings suggest that almonertinib and alflutinib may be potential therapeutic options for non-small cell lung cancer patients with the EGFR S768I mutation.

Prognostic and predictive biomarkers with therapeutic targets in nonsmall-cell lung cancer: A 2023 update on current development, evidence, and recommendation.

Since the publication of the original work in 2014, significant progress has been made in the characterization of genomic alterations that drive oncogenic addiction of nonsmall cell lung cancer (NSCLC) and how the immune system can leverage non-oncogenic pathways to modulate therapeutic outcomes. This update evaluates and validates the recent and emerging data for prognostic and predictive biomarkers with therapeutic targets in NSCLC. We performed a literature search from January 2015 to October 2023 using the keywords non-small cell lung cancer, clinical practice guidelines, gene mutations, genomic assay, immune cancer therapy, circulating tumor DNA, predictive and prognostic biomarkers, and targeted therapies. We identified, reviewed, and evaluated relevant clinical trials, meta-analyses, seminal articles, and published clinical practice guidelines in the English language. Regulatory-approved targeted therapies include those somatic gene alterations of EGFR ("classic" mutations, exon 20 insertion, and rare EGFR mutations), ALK, ROS1, BRAF V600, RET, MET, NTRK, HER2, and KRAS G12C. Data for immunotherapy and circulating tumor DNA in next-generation sequencing are considered emerging, whereas the predictive role for PIK3CA gene mutation is insufficient. Advances in sequencing and other genomic technologies have led to identifying novel oncogenic drivers, novel resistance mechanisms, and co-occurring mutations that characterize NSCLC, creating further therapeutic opportunities. The benefits associated with immunotherapy in the perioperative setting hold initial promise, with their long-term results awaiting.

Survival analysis of patients with advanced non-small cell lung cancer receiving EGFR-TKI treatment of Yunnan in southwestern China: a real-world study.

Patients with EGFR mutations who have advanced-stage non-small cell lung cancer (NSCLC) already receive tyrosine kinase inhibitors (TKIs) as the standard first-line therapy. Notably, Yunnan is a regional high incidence area of lung cancer in the highlands with a high rate of rare EGFR mutations. Overall, lung cancer patients in Xuanwei may present a distinct subgroup globally. Recent studies suggested that the NSCLC cohort in Xuanwei harbored a significantly higher uncommon mutation rate. However, little was known about the clinicopathological features and treatment efficacy of EGFR-TKI in Yunnan NSCLC patients. This study aimed to investigate the clinical impact of histologic type on the survival outcomes of patients with stage IIIB and IV NSCLC receiving EGFR-TKI treatment of Yunnan in southwestern China. In this retrospective study, we enrolled advanced NSCLC patients (IIIB-IV) with EGFR mutations who were first diagnosed and treated at Yunnan Cancer hospital from January 2016 to December 2019. Sociodemographics, lifestyle, survival, and clinicopathological characteristics of the patients were collected. The Kaplan-Meier method was used to assess the OS and PFS of patients. An analysis of prognostic factors was conducted using Cox regression. A total of 468 eligible patients were included. The median progression-free survival (PFS) and overall survival(OS) were 11.30(95% CI, 10.12-12.48) months and 30.30(95% CI, 26.24-34.36) months. Based on survival analysis among all the patients,females(HR=0.815;95% CI:0.671-0.989; P=0.017), Xuanwei origin (HR=0.776; 95% CI: 0.609-0.989; P=0.040), sample types(HR=0.780; 95% CI: 0.642-0.947; P=0.012) had a longer PFS. Multivariable analysis showed that only the sample type was an independent factor on median PFS with EGFR-TKI therapy. Patients less than 60 years old (HR=1.433; 95% CI:1.134-1.812, P=0.003)had better OS, but objectives with BMI≥24kg/m2(HR=0.653; 95% CI: 0.500-0.864; P=0.002), females(HR=0.776; 95% CI:0.613-0.982; P=0.035)and patients with tissue sample type (HR=0.760; 95% CI:0.600-.0961; P=0.022) had better OS. Notably, subgroup analysis of our study also found that PFS was significantly better in patients with G719X, L861Q, S768I, G719X+L861Q, and G719X+S768I in Xuanwei than classical mutation ones, including 19-Del and L858R (median 22.7 vs. 12.0 months, HR=0.523, P=0.010), while PFS was inferior in patients with rare mutations of EGFR in non-Xuanwei than the classical mutation ones (median 5.10 vs. 11.10 months, HR=1.760, P=0.015). NSCLC patients in Yunnan displayed a unique EGFR mutation profile, especially a higher prevalence of EGFR uncommon and compound mutations subtype. This study indicates prognostic factors of NSCLC treated with EGFR-TKI in Yunan and Xuanwei. This study will provide new clinical evidence for EGFR-TKI-targeted therapy in patients with rare EGFR mutations in China and worldwide. More researchs were needed for NSCLC EGFR-TKI therapy and medical insurance policy-making in Yunnan, Xuanwei area and uncommon especially.

EGFR assessment using next generation sequencing as a reflex testing on surgically resected non-squamous non-small cell lung carcinoma.

8539 Background: EGFR status assessment is mandatory in early stage (IB-IIIA) non-squamous non-small cell lung carcinoma (NS-NSCLC), but whether NGS methods should be used as reflex testing for this evaluation in daily practice is controversial. However, co-occuring mutations, notably TP53 mutations, may have an impact on tumor behavior and prognosis, and so, on future adjuvant therapeutic strategies. Methods: EGFR mutations were assessed prospectively using NGS (Oncomine Precision Assay genes panel) in 720 NS-NSCLC surgically resected between January 2021 and September 2022 in a single institution (LPCE, Nice, France). PD-L1 expression was evaluated in all tumors. Disease free survival (DFS) analysis was available in 675/720 (94%) patients. Results: EGFR mutations were detected in 83/720 (11.5%) cases. A common non-compound EGFR mutation (L858R or del19) was observed in 62/83 (75%) cases. 12/83 (14%) and 9/83 (11%) tumors had a rare non-compound and compound EGFR mutations, respectively. 40/83 (48%) has a co-occuring mutation, including a TP53 (30/40; 75%) mutation, mainly in exon 5, 7 or 8. EGFR/TP53 mutated tumors were significantly associated with higher PD-L1 expression compared to EGFR mutated tumors. A significant correlation was noted between worse DFS and the detection of a mutation in EGFR exon 18 mutation, as well as the detection of a co-mutation in TP53 exon 7 and in MET exon 14. Conclusions: Genomic alteration should be systematically evaluated using an NGS reflex testing in surgically resected NS-NSCLC, since future adjuvant therapeutic decision making may consider the presence of compound EGFR mutations as well as co-occuring mutations in other genes, especially in TP53.

Afatinib for the Treatment of NSCLC with Uncommon EGFR Mutations: A Narrative Review.

Afatinib, the world's first irreversible ErbB family (containing four different cancer cell epidermal growth factor receptors, including EGFR, HER2, ErbB3, and ErbB4) inhibitor, is a second-generation oral epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI). It can be used as a first-line treatment for locally advanced or metastatic non-small-cell lung cancer (NSCLC) with an EGFR-sensitive mutation or for patients with locally advanced or metastatic squamous lung cancer whose disease progresses during or after platinum-containing chemotherapy. Currently, with the use of third-generation EGFR-TKIs, afatinib is no longer clinically indicated as the first choice for patients with NSCLC who have EGFR-sensitive mutations. However, afatinib showed a considerable inhibitory effect in NSCLC patients with uncommon EGFR mutations (G719X, S768I, and L861Q) according to a combined post hoc analysis of the LUX-Lung2/3/6 trials. With the development of genetic testing technology, the detection rate of uncommon EGFR mutations is increasing. The aim of this paper is to describe in detail the sensitivity of rare EGFR mutations to afatinib and to provide information and a reference for those suffering from advanced NSCLC who have uncommon EGFR mutations.

Efficacy of EGFR-Tyrosine Kinase Inhibitors for advanced non-small cell lung cancer patients harboring rare EGFR mutations of exon 18 E709X.

EGFR-tyrosine kinase inhibitors (TKIs) show efficacy against lung cancer, and afatinib has been used as a standard therapy for patients with non-small cell lung cancer (NSCLC) with EGFR rare mutations such as S768I, G719X, and L861Q. However, the efficacy of EGFR-TKIs against NSCLC with EGFR rare mutations of exon 18 E709X has been less studied. The present study aimed to analyze the efficacy and safety of EGFR-TKIs in NSCLC patients with rare mutations. Our study enrolled 15 NSCLC patients with exon 18 E709X mutation who were admitted to Zhejiang Cancer Hospital. The objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and treatment-related adverse events (TRAEs) were analyzed. The ORR of the entire cohort of patients was 33.3%. The PFS of all patients with exon 18 E709X mutations was 10.9months. The OS was not reached. The PFS of patients with exon 18 E709-T710delinsD and E709A/G/K mutations showed no significant difference (5.3 vs. 13.5months, P = 0.238). A significant difference in OS was observed between patients with exon 18 E709-T710delinsD mutation and those with E709A/G/K mutation (12.2months vs. not reached, P = 0.029). No significant difference in efficacy was observed between second- and third-generation TKIs for NSCLC patients with exon 18 E709X mutations (PFS: 13.5 vs. 10.9months, P = 0.774; OS: 17.1months vs. not reached, P = 0.072). New treatment-related adverse events were not observed. NSCLC patients with exon 18 E709X mutations may benefit from treatment with second- or third-generation EGFR-TKIs.

Validation of a highly sensitive Sanger sequencing in detecting EGFR mutations from circulating tumor DNA in patients with lung cancers

BackgroundThe novel method, named blocker displacement amplification (BDA) Sanger, was applied to detect low variant allele frequency mutations in the circulating tumor DNA (ctDNA). This study aimed to evaluate the performance of the BDA Sanger method for the EGFR mutation detection in the ctDNA from lung cancer patients. MethodsA total of 195 plasma samples of lung cancer patients were included. The EGFR mutation status in the ctDNA was detected by the BDA Sanger and Super-ARMS assays. Next-generation sequencing (NGS) was further used to verify the mutant of EGFR with inconsistencies. ResultsBDA Sanger assay was capable of detecting EGFR mutations with a 0.20% VAF from plasma samples. Among treatment-naive patients with paired tissue and plasma samples, the EGFR positive percent agreement (PPA) was 79% by BDA sanger. EGFR mutation was detected in 34.4% (67/195) ctDNA samples by the Super-ARMS and in 41.0% (80/195) ctDNA samples by the BDA Sanger assay. The overall concordance rate between the BDA Sanger and Super-ARMS assays was 82% (160/195). The BDA Sanger also enabled the detection of rare EGFR mutations, which were not discovered by the Super-ARMS. ConclusionThe results supported the validity and efficiency of the BDA Sanger method for EGFR detection in patients with lung cancer, indicating that BDA Sanger has a great potential for application in detecting mutations in the ctDNA.

EP08.02-065 Response to Systemic Anti-Cancer Therapy in Uncommon EGFR Mutations

Exon 19 deletions, exon 21 L858R and exon 20 insertions represent the most frequent alterations in EGFR mutated non-small cell lung cancer (NSCLC). These alterations now all have approved targeted therapies. In contrast, there is limited data assessing activity of EGFR-directed therapy for uncommon EGFR alterations. We sought to describe clinical outcomes of patients with rare EGFR mutations that received systemic anticancer therapy (SACT) at our institution.

EP11.01-003 Advanced Non Small Cell Lung Cancer With EGFR Exon 20 Insertion Gene Mutation

The EGFR Exon 20 Inserton mutation is belongs to the group of rare EGFR mutations and that is resistant to TKIs generation I-II-III. We conduct research with the following objectives: a. Survey on the rate of EGFR Exon 20 Insertion mutations in patients with advanced NSCLC. b. Survey of subtypes of EGFR mutations Exon 20 Insertion offers applications in clinical practice.

Abstract 4113: Response to amivantamab, a bispecific EGF and MET receptor directed antibody, in a patient with an atypical EGFR mutated (G719X) non-small cell lung cancer (NSCLC) with leptomeningeal disease who progressed on osimertinib

Abstract Amivantamab is a bispecific antibody against EGF and MET receptors, approved for patients with locally advanced or metastatic NSCLC harboring EGFR exon 20 insertion after disease has progressed on or after platinum-based chemotherapy. Existing data is insufficient in establishing its efficacy on other rare EGFR mutated subtypes, central nervous system (CNS), or its resistance to 3rd generation tyrosine kinase inhibitor (TKI), osimertinib. Here, we report a case showing a good response on single agent amivantamab in an atypical EGFR mutation (G719A, exon18 substitution) NSCLC that progressed to CNS involvement on osimertinib. A 67-year-old male presented with stage IVB squamous cell carcinoma of lung with osseous metastases. CT chest, abdomen, and pelvis revealed a speculated 7.7 cm right upper lung lesion with hilar and subcarinal lymphadenopathies. MRI brain and spine showed multiple bone metastases without CNS involvement. Tissue biopsy confirmed poorly differentiated squamous cell carcinoma with PD-L1 IHC 75%. Tissue next generation sequencing (NGS) showed EGFR G719A. He was started on osimertinib. Two months later, he was hospitalized for drug-induced pneumonitis which prompted off osimertnib. CT angiogram chest showed new diffuse pericardial thickening and nodularity, suggestive of progressive disease. Two cycles of chemotherapy were delivered followed by immunotherapy with ipilimumab and nivolumab. In 10 weeks, progression of disease was revealed in MRI brain demonstrating new parenchymal and leptomeningeal metastases. Amivantamab monotherapy was initiated with discontinuation of immunotherapy. The patient tolerated amivantamab without major complications. His performance status remained the same before and after amivantamab. He denied fatigue, anorexia, nausea or vomiting, however, endorsed rash, which was managed with hydrocortisone cream. Repeat scans in 6 weeks showed decreased leptomeningeal enhancement, and reduction in the size of parenchymal lesions, lung mass, and lymphadenopathies. The highest variant allele fraction from circulating tumor DNA NGS assay from Guardant360 was significantly improved on amivantamab from 25.6% (EGFR G719A), at time of diagnosis, to non-detectable. Amivantamab monotherapy has shown an encouraging outcome in a patient with an atypical EGFR mutated (G719X) NSCLC with leptomeningeal disease who progressed on osimertinib. Our case has shown significant response on CNS involvements, which is contrary to known poor blood-brain barrier penetration of amivantamab. This supports current trial evaluating the efficacy of amivantamab for NSCLC with rare EGFR mutations such as G719X, and ones progressed on 3rd Gen TKI treatment. Additional studies evaluating the efficacy of amivantamab on CNS metastasis are warranted. Citation Format: Jinah Kim, Horyun Choi, Yeun Ho Lee, Leeseul Kim, Young Kwang Chae. Response to amivantamab, a bispecific EGF and MET receptor directed antibody, in a patient with an atypical EGFR mutated (G719X) non-small cell lung cancer (NSCLC) with leptomeningeal disease who progressed on osimertinib [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4113.

Abstract 527: A streamlined workflow for liquid biopsy extraction and highplex digital PCR analysis using the Maxwell® RSC system and 6-color Crystal Digital PCR™

Abstract Circulating cell free DNA (cfDNA) extracted from liquid biopsy samples have become established sample types for characterizing oncology targets. Currently, there are several extraction protocols and genomic platforms for researchers to select when interrogating genetic information. The focus of this work was to identify a flexible method for sample extraction that seamlessly integrates into a straightforward and sensitive genetic analysis workflow from plasma samples. Here, we present a workflow combining the Maxwell RSC system for automated cfDNA extraction and Crystal Digital PCR on the naica system for ultrasensitive high-plex detection from liquid biopsy samples of EGFR mutations in non-small cell lung cancer (NSCLC) and PIK3CA mutations and HER2 amplification in breast cancer. By bridging sample extraction with the Maxwell RSC system and high-plex digital PCR with the 6-color naica® system, we detected with high sensitivity and precision 32 common and rare somatic EGFR mutations in exons 18, 19, 20, and 21, representing more than 90% of EGFR mutations described in NSCLC. Furthermore, following the same extraction and sample testing workflow, we simultaneously detected a set of PIK3CA mutations and HER2 amplification from cfDNA samples. This proof-of-concept workflow creates the foundation for further development of streamlined sample-to-answer protocols that will better assist cancer researchers across the biomarker testing landscape. Citation Format: Cécile Jovelet, Myrtille Remy, Mylene Menanteau, Doug White, Douglas Horejsh, Allison Mallory. A streamlined workflow for liquid biopsy extraction and highplex digital PCR analysis using the Maxwell® RSC system and 6-color Crystal Digital PCR™ [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 527.

High Tumor Mutational Burden in Rare and Complex EGFR Mutant Non-Small Cell Lung Cancer

<h3>Purpose/Objective(s)</h3> Classical EGFR mutant lung cancer with exon 19 deletions, exon 21 L858R and de novo exon 20 T790M mutations are associated with good response to tyrosine kinase inhibitors. In contrast, rare and complex mutations have uncertain or poor response to targeted therapy. Recent retrospective analyses have observed a potential benefit of rare and complex EGFR mutations from immunotherapy, in contrast to cancers harboring classical EGFR mutations. We hypothesized that a larger proportion of rare and complex EGFR mutant lung cancers may have molecular differences that would promote immune checkpoint blockade as a putative combination or alternative treatment. <h3>Materials/Methods</h3> Patients (pts) with nonsynonymous EGFR mutant lung cancers from two datasets (The Cancer Genome Atlas, Clinical Proteomic Tumor Analysis Consortium) were identified. Rare EGFR mutations were defined as non-sensitizing somatic mutations occurring within the tyrosine kinase (TK) domain of exons 18 through 21. Complex EGFR mutant cases (i.e., G719X + S768I) were tumors with two mutations within the TK region where at least one mutation was non-sensitizing. Tumor mutational burden (TMB) was calculated as the number of somatic mutations per million bases (human exome was estimated to be 38 Mb). High-TMB was denoted as a TMB over 10. Gene expression of PD-L1 was evaluated by RNA-sequencing as well as bioinformatic assessment of tumor purity, immune infiltration and stroma contribution within the tumor microenvironment using the ESTIMATE (Estimation of STromal and Immune cells in MAlignant Tumours using Expression data) algorithm. <h3>Results</h3> Of the 675 pts evaluated, 97 (14.3%) had tumors which harbored EGFR mutations. Patients with EGFR mutant tumors were more likely to be female (64 vs 48%, <i>P</i> = 0.006) and non-smokers (49 vs 12%, <i>P</i> < 0.001). Tumors from non-smokers were less likely to have high-TMB (<i>P</i> < 0.001). Twenty four of 97 (25%) EGFR mutant cancers had either rare (n = 12) or complex mutations (n = 12). Tumors with rare/complex EGFR mutations had a higher average TMB (5.4 compared to 2.3) and were significantly more likely to have a TMB over 10 (17% vs 1.4%, <i>P</i> = 0.003). 25% of rare EGFR mutant tumors (L861Q, E866K, K754I) had a TMB > 10 (<i>P</i> = 0.0003). There were no significant differences in PD-L1 expression (<i>P</i> = 0.46) or smoking history (<i>P</i> = 0.71) between classical and rare/complex EGFR mutant cancers. Tumors with rare EGFR mutations had significantly higher tumor purity (0.759 versus 0.459, <i>P</i> = 0.0038), and corresponding lower proportion of immune (<i>P</i> = 0.0045) and stromal cells (<i>P</i> = 0.0077). <h3>Conclusion</h3> Our data suggests that lung cancers harboring rare EGFR mutations may have mutation-specific dependencies that would make a non-significant proportion amenable to immunotherapy. While PD-L1 appears to be a poor biomarker, we observed an increase in high-TMB and distinct changes in the tumor microenvironment in rare EGFR mutant lung cancer.

Targeting the Epidermal Growth Factor Receptor in EGFR-Mutated Lung Cancer: Current and Emerging Therapies.

Simple SummaryEpidermal growth factor receptor (EGFR) mutations occur in a significant number of lung cancer patients. Treatment outcomes in this subset of patients has greatly improved over the last decade after the introduction of EGFR tyrosine kinase inhibitors (TKIs), which demonstrated high efficacy and improved survival in randomized clinical trials. Although EGFR TKIs became the standard of care in patients with EGFR-mutated lung cancer, resistance almost inevitably develops. This constitutes a major challenge and creates an unmet need for novel therapies and new approaches to ameliorate or overcome this resistance. In this review we discuss currently approved TKIs for the targeted management of EGFR-mutated lung cancer. We also review common mechanisms of resistance to EGFR-targeted therapies and describe promising approaches that may mitigate resistance.Epidermal growth factor receptor-targeting tyrosine kinase inhibitors (EGFR TKIs) are the standard of care for patients with EGFR-mutated metastatic lung cancer. While EGFR TKIs have initially high response rates, inherent and acquired resistance constitute a major challenge to the longitudinal treatment. Ongoing work is aimed at understanding the molecular basis of these resistance mechanisms, with exciting new studies evaluating novel agents and combination therapies to improve control of tumors with all forms of EGFR mutation. In this review, we first provide a discussion of EGFR-mutated lung cancer and the efficacy of available EGFR TKIs in the clinical setting against both common and rare EGFR mutations. Second, we discuss common resistance mechanisms that lead to therapy failure during treatment with EGFR TKIs. Third, we review novel approaches aimed at improving outcomes and overcoming resistance to EGFR TKIs. Finally, we highlight recent breakthroughs in the use of EGFR TKIs in non-metastatic EGFR-mutated lung cancer.

Treatment outcome and functional characterization of uncommon EGFR mutations in the German National Network Genomic Medicine Lung Cancer (nNGM).

9036 Background: The nNGM centralizes molecular diagnostics, treatment recommendations and follow-up reporting in NSCLC in Germany. Uncommon EGFR mutations pose a clinical challenge because they comprise a heterogenous group and analyses of treatment outcome are still scarce. Here, we analyzed follow-up data of patients with rare EGFR mutations and performed functional characterization of recurrent mutations with unknown function. Methods: This multicenter, retrospective analysis of uncommon EGFR mutations (excluding L858R-, T790M mutations and exon 19 deletions) includes stage IV patients with NSCLC from 12 nNGM centers. We categorized EGFR-mutations into 3 groups: uncommon EGFR mutations with known driver function, for instance E709X, G719X, S768I and L861Q (group 1), exon 20 insertions (group 2) and all other very rare mutations (group 3). Functional characterization of unknown mutations was performed by insertion mutagenesis in Ba/F3 cells and monitoring of growth factor-independent proliferation. Results: In total, 834 cases with uncommon EGFR mutations were reported. Follow-up data after EGFR-TKI (Erlotinib, Gefitinib, Afatinib and Osimertinib), chemotherapy and/or mono-PD(L)1 blockade was available for 252 patients. Mean progression free survival (mPFS) on EGFR-TKIs vs. chemotherapy was 6.6 months vs. 5.0 months (HR 0.54, 95%CI 0.35 to 0.81, P =.003) in group 1 (n = 84), and 6.7 months vs. 3.4 months (HR 0.66, 95%CI 0.47 to 0.92, P =.015) in group 3 (n = 104). Mono-anti-PD(L1) blockade was not superior to chemotherapy (group 1, mPFS 3.0 months, HR 1.32, 95% 0.55 – 3.15, P =.535 and group3, mPFS 4.3 months, HR 1.02, 95% CI 0.64 – 1.62, P = 0.951). Exon 20 insertions (group 2, n = 63) did not benefit from EGFR-TKIs or anti-PD(L1) blockade vs. chemotherapy. Overall survival (OS) analysis (n = 218) following chemotherapy (56%) or EGFR-TKI treatment (44%) showed median OS (mOS) of 18.0 months vs. 13.9 months in patients treated with EGFR-TKI and chemotherapy, respectively in group 1 (HR 0.97, 95%CI 0.54 to 1.75, P =.929). In group 3 patients treated with EGFR-TKI and chemotherapy had a mOS of 35.4 months vs. 12.0 months, respectively (HR 0.59, 95%CI 0.35 to 1.01, P =.056). In the Ba/F3 system we could identify 8 recurrent driver and 12 non-driver mutations with a clinically applicable assay turnaround time of 4 weeks to inform clinical decision-making in the future. Conclusions: This real-world dataset confirms that patients with group 1(uncommon) EGFR mutations benefit from EGFR-TKIs and indicates that mono-anti PD(L)1 blockade is not superior to chemotherapy. Furthermore, patients with very rare EGFR mutations (group 3) also experienced a PFS benefit from EGFR-TKI compared to chemotherapy while immune therapy was not beneficial.

P76.98 NSCLC Patients With Rare EGFR Mutations in Exons 18 and 19 Benefits From Treatment With EGFR Tyrosine Kinase Inhibitors

P76.98 NSCLC Patients With Rare EGFR Mutations in Exons 18 and 19 Benefits From Treatment With EGFR Tyrosine Kinase Inhibitors

Efficacy of afatinib in a patient with rare EGFR (G724S/R776H) mutations and amplification in lung adenocarcinoma: A case report

BACKGROUNDThe most common EGFR mutations are in-frame deletions in exon 19 and point mutations in exon 21. Cases with classical EGFR mutations show a good response to EGFR tyrosine kinase inhibitors (TKIs), the standard first-line treatment. With the development of next generation sequencing, some uncommon genomic mutations have been detected. However, the effect of TKIs on such uncommon EGFR mutations remains unclear.CASE SUMMARYHere, we report a case of rare EGFR co-mutation in non-small cell lung cancer and the efficacy of afatinib on this EGFR co-mutation. A 64-year-old woman was diagnosed with thoracolumbar and bilateral local rib bone metastases, bilateral pulmonary nodules, and pericardial and left pleural effusion. The pathological diagnosis was lung adenocarcinoma. To seek potential therapeutic regimens, rare co-mutation comprising rare EGFR G724S/R776H mutations and amplification were identified. The patient experienced a significant clinical response with a progression-free survival of 17 mo. CONCLUSIONA case of non-small cell lung cancer with rare EGFR G724S/R776H mutations and EGFR amplification responds well to TKI treatment.

Osimertinib, an Irreversible Next-Generation EGFR Tyrosine Kinase Inhibitor, Exerts Antitumor Activity in Various Preclinical NSCLC Models Harboring the Uncommon EGFR Mutations G719X or L861Q or S768I.

Osimertinib is an oral, third-generation, irreversible epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) that selectively inhibits both EGFR-TKI-sensitizing and EGFR T790M-resistance mutations with lower activity against wild-type EGFR and has demonstrated efficacy in non-small cell lung cancer (NSCLC) CNS metastases. The sensitizing mutations, the in-frame deletions in exon 19 and the L858R point mutation in exon 21, represent between 80% and 90% of all EGFR mutations. The remaining 10% to 20% are referred to as uncommon activating mutations and are a diverse group of mutations in exons 18 to 21 within the kinase domain of the EGFR gene. Excluding those found as insertion mutations in exon 20, the uncommon mutations involving codons G719, S768, and L861 are the most prevalent.Although the efficacy of EGFR-TKIs for the common EGFR mutations is well established, much less is known about rare EGFR mutations, such as exon 20 insertions, G719X, L861Q, S768I, as most of the data consist of single case reports or small case series.Using available patient-derived xenografts (PDX) and cell lines derived from two of these PDXs that harbor the G719X mutation, we have evaluated in vitro and in vivo the preclinical activity of osimertinib. We report osimertinib inhibits signaling pathways and cellular growth in G719X-mutant cell lines in vitro and demonstrate sustained tumor growth inhibition of PDX harboring the G719X mutation alone or in combination with L861Q and S768I.Together, these data support clinical testing of osimertinib in patients with uncommon EGFR NSCLC.

Oncogenic Genetic Alterations in Non-Small-Cell Lung Cancer (NSCLC) in Southwestern China.

PurposeTo investigate the impact of oncogenic genetic alterations (GAs) on non-small-cell lung cancer (NSCLC) in southwestern China.Patients and MethodsWe first collected 579 pathologically confirmed NSCLC specimens and then used next-generation sequencing (NGS) to evaluate the DNA samples for GAs. Both the tissue and plasma samples were provided by 28 patients. Furthermore, subgroup analyses based on sample type, concordance, and GA type were carried out.ResultsGAs were detected by NGS in 61.8% (358/579) of patients. Two hundred and twenty-nine patients (39.6%) harbored EGFR mutations, 63 (10.9%) harbored KRAS mutations, 13 (2.2%) harbored BRAF mutations, 30 (5.18%) harbored ALK fusions, and 13 (2.2%) had ROS1 fusions. We found that females (p < 0.01), nonsmokers (p < 0.001), adenocarcinoma (p < 0.001), and tissue (p = 0.03) had a relatively high EGFR mutation rate. Notably, NSCLC patients from Xuanwei had a significantly different mutational pattern for EGFR in comparison with that of non-Xuanwei patients (higher G719X + S768I mutations and multiple gene alterations, but fewer exon 19 deletion mutations and single gene alterations). We found that adenocarcinoma (p = 0.02), family history of malignancy (p = 0.03), Xuanwei origin (p < 0.001), and tissue (p = 0.04) were associated with a higher number of KRAS mutations. Subgroup analysis showed that ALK (p < 0.001) and ROS1 (p < 0.05) fusions and rare EGFR mutations (p < 0.001) were associated with non-Han ethnic patients.ConclusionYunnan NSCLC patients from Xuanwei and non-Han ethnic patients had an obviously unique prevalence of GAs.

Identification and in silico structural insights of rare recurrent EGFR mutations as resistance mechanisms to osimertinib in EGFR-mutated lung cancer.

9531 Background: Inevitable progression on 3rd-generation EGFR-tyrosine kinase inhibitor (TKI) osimertinib of EGFR-mutated lung cancer patients represents a great challenge in clinic. Previous studies have revealed that one-third of the resistant mechanisms are due to acquired EGFR secondary mutations, mainly on C797, L718 and L792 residues. Our study aims to gain insights into novel mechanisms of acquired resistance to osimertinib. Methods: We performed genomic profiling on a total of 1,058 EGFR-mutated lung cancer patients with progressed disease on osimertinib, and a cohort of 1,803 patients who received only 1st-generation EGFR TKIs upon progression. Recurrent EGFR mutations with a significant enrichment in the osimertinib group were identified. We further established and applied molecular dynamic simulation-based computational model of the mutant EGFR protein to predict its sensitivity to osimertinib. Results: As expected, compared with 1st-TKIs alone group, EGFR mutations, including C797S/G (22.1% vs. 0.5%), L718Q/V (6.2% vs. 0.3%), L792F/H (4.4% vs. 0.3%), were significantly more enriched in the osimertinib cohort. Our computational model has also successfully predicted their sensitivities to osimertinib: WT (-35.19 kcal/mol) &gt; L792F (-34.10 kcal/mol) &gt; L718Q (-30.33kcal/mol) &gt; C797S (-28.02 kcal/mol), which are consistent with our previous in vitro validations. Importantly, a total of 14 low-frequency EGFR mutations were exclusively observed in the osimertinib group, seven of which, including EGFR G796S(n = 6), V802F(n = 3), T725M(n = 2), Q791L/H(n = 2), P794S/R(n = 2), were predicted to dramatically reduce the binding affinity of osimertinib to EGFR. Of note, analysis of the pretreatment samples of two patients supported that EGFR V802F and Q791L/H were acquired during osimertinib treatment. Interestingly, EGFR G796S was predicted to be sensitive to gefitinib, suggesting the possibility of administration of gefitinib in patients with acquired EGFR G796S to first-line osimertinib treatment. Further in vitro functional validations are currently ongoing. Conclusions: Our study represents the largest EGFR-mutated lung cancer cohort so far to investigate osimertinib resistance in a real-world setting, and has uncovered a list of recurrent low-frequency EGFR mutations that may confer acquired resistance to osimertinib. Our in silico structural model was proved to be powerful and robust in the prediction of osimertinib sensitivity of EGFR mutants.

Rapid detection of EGFR mutations in decalcified lung cancer bone metastasis

Detection of molecular alterations in lung cancer bone metastasis (LCBM) is particularly difficult when decalcification procedure is needed. The Idylla™ real-time (RT)-PCR is compared to the routine method used in our laboratory, which combines next generation and Sanger sequencing, for the detection of EGFR mutations in LCBM.LCBM subjected to EDTA or formic acid decalcification were analysed for EGFR mutational status using two methods: first, the Ion Torrent Ampliseq next generation sequencing (NGS) assay +/- Sanger sequencing was used prospectively; then, the fully-automated, RT-PCR based molecular testing system Idylla™ EGFR Mutation Test was applied retrospectively.Out of the 34 LCBM assayed, 14 (41.2%) were unsuitable for NGS analysis and five remained unsuitable after additional Sanger EGFR sequencing (5/34, 14.7%). Using Idylla™, valid results were observed for 33/34 samples (97.1%). The concordance between the NGS +/- Sanger sequencing method and the RT-PCR method was 89.7% (26/29), one false positive EGFR S768I mutation and two false negative results were observed using Idylla™; one of these false negative cases was diagnosed by Sanger sequencing with a rare exon 19 EGFR mutation not covered by the Idylla™ EGFR Mutation Test design.Detection of EGFR mutations in decalcified LCBM is challenging using NGS, more than half of samples showing invalid results. Alternative methods should thus be preferred to spare clinical samples and decrease delay. The Idylla™ EGFR Mutation Test shows a good performance on decalcified bone samples and could be used as a first step. In case of negative results, a sequencing approach is mandatory to check the presence of rare EGFR mutations sensitive to EGFR tyrosine kinase inhibitors.