Epidermal Growth Factor Receptor Amplification Research Articles

The association of EGFR amplification with aberrant exon 20 insertion report using the cobas EGFR Mutation Test v2.

Determining the exact type of epidermal growth factor receptor (EGFR) exon 20 insertion (ex20ins) mutation in lung cancer has become important. We found that not all ex20ins mutations reported by cobas EGFR test v2 could be validated by Sanger sequencing even using surgical specimens with high tumor contents. This study aimed to validate the ex20ins results reported by the cobas test and to determine whether there were clinicopathological factors associated with aberrant cobas ex20ins report. In total, 123 cobas-reported cases with ex20ins were retrospectively collected and validated by Sanger sequencing and Idylla assay. Clinicopathological features between ex20ins cobas+/Sanger+ group (n = 71) and cobas+/Sanger- group (n = 52) were compared. The Idylla assay detected ex20ins in 82.6% of cobas+/Sanger+ cases but only in 4.9% of cobas+/Sanger- cases. The cobas+/Sanger- group was significantly associated with higher tumor contents, poorly differentiated patterns, tumor necrosis, and a lower internal control cycle threshold value reported by the Idylla which suggesting the presence of increased EGFR gene copy numbers. EGFR fluorescence in situ hybridization (FISH) revealed the majority of cobas+/Sanger- group had EGFR high copy number gain (16%) or amplification (76%) according to the Colorado criteria. Among cases reported to have concomitant classic EGFR and ex20ins mutations by the cobas, the classic EGFR mutations were all detected by Sanger sequencing and Idylla, while the ex20ins mutations were undetected by Sanger sequencing (0%) or rarely reported by Idylla assay (3%). FISH revealed high EGFR copy number gain (17.9%) and amplification (79.5%) in cases reported having concomitant classic EGFR and ex20ins mutations by the cobas. This study demonstrated an unusually high frequency of EGFR amplification in cases with aberrant cobas ex20ins report which could not be validated by Sanger sequencing or Idylla assay. Ex20ins reported by the cobas test should be validated using other methods especially those reported having concomitant ex20ins and classic EGFR mutations.

Ensemble learning prediction framework for EGFR amplification status of glioma based on terahertz spectral features

Epidermal growth factor receptor (EGFR) plays a pivotal role in the initiation and progression of gliomas. In particular, in glioblastoma, EGFR amplification emerges as a catalyst for invasion, proliferation, and resistance to radiotherapy and chemotherapy. Current approaches are not capable of providing rapid diagnostic results of molecular pathology. In this study, we propose a terahertz spectroscopic approach for predicting the EGFR amplification status of gliomas for the first time. A machine learning model was constructed using the terahertz response of the measured glioma tissues, including the absorption coefficient, refractive index, and dielectric loss tangent. The novelty of our model is the integration of three classical base classifiers, i.e., support vector machine, random forest, and extreme gradient boosting. The ensemble learning method combines the advantages of various base classifiers, this model has more generalization ability. The effectiveness of the proposed method was validated by applying an individual test set. The optimal performance of the integrated algorithm was verified with an area under the curve (AUC) maximum of 85.8 %. This signifies a significant stride toward more effective and rapid diagnostic tools for guiding postoperative therapy in gliomas.

Abstract 6504: Exploratory analysis using serial cell-free DNA in patients treated with amivantamab in non-small cell lung cancer with EGFR exon 20 insertion mutations

Abstract Introduction: Epidermal growth factor receptor (EGFR) exon 20 insertion (ex20 ins) mutation showed limited clinical activity with conventional EGFR tyrosine kinase inhibitors (TKIs). Amivantamab is the first bispecific antibody to be approved for the treatment of metastatic non-small cell lung cancer (NSCLC) with EGFR ex20ins mutation. However, limited data is available in terms of predictive biomarkers and the resistance mechanism. In this study, we conducted an exploratory analysis to elucidate a genomic landscape using circulating tumor DNA (ctDNA) from plasma samples. Patients and Methods: This study include result from 79 blood samples, which has been prospectively collected from 27 EGFR ex20ins mutated NSCLC patients (confirmed by either tissue or plasma-based test) who were treated with amivantamab. ctDNAs were obtained from plasma, which was serially collected at baseline, after 2 cycles of treatment, 2 cycles prior to the treatment discontinuation, and at the time point of disease progression. Guardant OMNI panel (Guardant Health, CA, USA) was used for the genomic profiling. Results: The median follow-up duration was 5.8 months (range 2.7-12.7). The overall response rate was 40.7% (95% confidence interval [CI] 24.5-59.2, n=11), and median progression-free survival was 5.8 months (95% CI 3.9-15.9) with a median duration of response of 9.8 months (95% CI, 7.3-NA). Patients with EGFR ex20ins not detected from ctDNA at baseline (n=10) showed significantly longer PFS compared to patients with EGFR ex20ins identified at baseline plasma sample (n=17) (14.6 vs 3.9 months; hazard ratio [HR] 0.40, 95% CI 0.17-0.95, P<0.05).The most common concurrent somatic variations at baseline were TP53 (62.9%), TERT (18.5%), ATM (18.5%). Longer median PFS was observed in patients without EGFR amplification (n=18) compared to patients with concurrent EGFR amplification (n=9) (11.1 vs. 2.5 months; HR 0.30, 95% CI 0.11-0.77, P <0.05). The presence of plasma EGFR ex20ins at C2D15 predicted poor PFS (17.8 vs 2.7 months; HR 0.17, 95% CI 0.06-0.47, P <0.01), regardless of baseline its presence or absence. Based on the paired analysis using baseline and at the timepoint of disease progression, putative resistance mechanism to amivantamab was identified in 14 patients (60.8%), which were PDGFRB (28.5%), followed by PTEN (21.4%), CHEK2 (21.4%). Conclusions: This study provides a comprehensive longitudinal ctDNA analysis in patients with EGFR ex20ins mutant NSCLC who were treated with amivantamab. Our results suggested that the presence of ctDNA for EGFR ex20ins mutation and co-alteration with EGFR amplification at baseline might be related to the clinical outcomes of amivantamab. Citation Format: Geun-Ho Park, Sehhoon Park, Hyen-Ae Jung, Jong-Mu Sun, Jin Seok Ahn, Myung-Ju Ahn, Se-Hoon Lee. Exploratory analysis using serial cell-free DNA in patients treated with amivantamab in non-small cell lung cancer with EGFR exon 20 insertion mutations [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 6504.

Revealing the role of SPP1+ macrophages in glioma prognosis and therapeutic targeting by investigating tumor-associated macrophage landscape in grade 2 and 3 gliomas

BackgroundGlioma is a highly heterogeneous brain tumor categorized into World Health Organization (WHO) grades 1–4 based on its malignancy. The suppressive immune microenvironment of glioma contributes significantly to unfavourable patient outcomes. However, the cellular composition and their complex interplays within the glioma environment remain poorly understood, and reliable prognostic markers remain elusive. Therefore, in-depth exploration of the tumor microenvironment (TME) and identification of predictive markers are crucial for improving the clinical management of glioma patients.ResultsOur analysis of single-cell RNA-sequencing data from glioma samples unveiled the immunosuppressive role of tumor-associated macrophages (TAMs), mediated through intricate interactions with tumor cells and lymphocytes. We also discovered the heterogeneity within TAMs, among which a group of suppressive TAMs named TAM-SPP1 demonstrated a significant association with Epidermal Growth Factor Receptor (EGFR) amplification, impaired T cell response and unfavourable patient survival outcomes. Furthermore, by leveraging genomic and transcriptomic data from The Cancer Genome Atlas (TCGA) dataset, two distinct molecular subtypes with a different constitution of TAMs, EGFR status and clinical outcomes were identified. Exploiting the molecular differences between these two subtypes, we developed a four-gene-based prognostic model. This model displayed strong associations with an elevated level of suppressive TAMs and could be used to predict anti-tumor immune response and prognosis in glioma patients.ConclusionOur findings illuminated the molecular and cellular mechanisms that shape the immunosuppressive microenvironment in gliomas, providing novel insights into potential therapeutic targets. Furthermore, the developed prognostic model holds promise for predicting immunotherapy response and assisting in more precise risk stratification for glioma patients.Graphical abstract

EGFR amplification and EGFRvIII predict and participate in TAT-Cx43266-283 antitumor response in preclinical glioblastoma models.

Glioblastoma (GBM) commonly displays epidermal growth factor receptor (EGFR) alterations (mainly amplification and EGFRvIII) and TAT-Cx43266-283 is a Src-inhibitory peptide with antitumor properties in preclinical GBM models. Given the link between EGFR and Src, the aim of this study was to explore the role of EGFR in the antitumor effects of TAT-Cx43266-283. The effect of TAT-Cx43266-283, temozolomide (TMZ) and erlotinib (EGFR inhibitor) was studied in patient-derived GBM stem cells (GSCs) and murine neural stem cells (NSCs) with and without EGFR alterations, in vitro and in vivo. EGFR alterations were analyzed by Western blot (WB) and Fluorescence In Situ Hybridization (FISH) in these cells, and compared with Src activity and survival in GBM samples from TCGA. The effect of TAT-Cx43266-283 correlated with EGFR alterations in a set of patient-derived GSCs and was stronger than that exerted by TMZ and erlotinib. In fact, TAT-Cx43266-283 only affected NSCs with EGFR alterations, but not healthy NSCs. EGFR alterations correlated with Src activity and poor survival in GBM patients. Finally, tumors generated from NSCs with EGFR alterations, showed a decrease in growth, invasiveness and vascularization after treatment with TAT-Cx43266-283, which enhanced the survival of immunocompetent mice. Clinically relevant EGFR alterations are predictors of TAT-Cx43266-283 response and part of its mechanism of action, even in TMZ- and erlotinib-resistant GSCs. TAT-Cx43266-283 targets NSCs with GBM-driver mutations, including EGFR alterations, in an immunocompetent GBM model in vivo, suggesting a promising effect on GBM recurrence. Together, this study represents an important step towards the clinical application of TAT-Cx43266-283.

Molecular GBM versus Histopathological GBM: Radiology-Pathology-Genetic Correlation and the New WHO 2021 Definition of Glioblastoma.

Given the recent advances in molecular pathogenesis of tumors, with better correlation with tumor behavior and prognosis, major changes were made to the new 2021 WHO (CNS5) classification of CNS tumors, including updated criteria for diagnosis of glioblastoma. Diagnosis of GBM now requires absence of isocitrate dehydrogenase and histone 3 mutations (IDH-wildtype and H3-wildtype) as the basic cornerstone, with elimination of the IDH-mutated category. The requirements for diagnosis were conventionally histopathological, based on the presence of pathognomonic features such as microvascular proliferation and necrosis. However, even if these histological features are absent, many lower grade (WHO grade 2/3) diffuse astrocytic gliomas behave clinically similar to GBM (grade 4). The 2021 WHO classification introduced new molecular criteria that can be used to upgrade the diagnosis of such histologically lower-grade, IDH-wildtype, astrocytomas to GBM. The three molecular criteria include: concurrent gain of whole chromosome 7 and loss of whole chromosome 10 (+7/-10); TERT promoter mutation; epidermal growth factor receptor (EGFR) amplification. Given these changes, it is now strongly recommended to have molecular analysis of WHO grade 2/3 diffuse astrocytic, IDH-wildtype, gliomas in adult patients, as identification of any of the above mutations allows for upgrading the tumor to WHO grade 4 ("molecular GBM") with important prognostic implications. Despite at an early stage, there is active ongoing research on the unique MRI features of molecular GBM. This paper highlights the differences between "molecular" and "histopathological" GBM, with the aim of providing a basic understanding about these changes.ABBREVIATIONS: GBM=Glioblastoma; TERT=telomerase reverse transcriptase; EGFR=epidermal growth factor receptor; MGMT= methylguanine-DNA methyltransferase; NGS= next-generation sequencing; IDH= isocitrate dehydrogenase.

Treatment options for HER2-expressing colorectal cancer: updates and recent approvals.

Colorectal cancer is a leading cause of cancer-related mortality worldwide. Approximately 3-5% of colorectal tumors harbor human epidermal growth factor receptor (HER2) amplification which is associated with a higher incidence of intracranial metastasis and overall worse outcomes. In the setting of refractory metastatic RAS wild-type tumors, evidence supports the use of various HER2-blocking agents, including monoclonal antibodies, tyrosine kinase inhibitors, and novel antibody-drug conjugates. With a number of relatively active agents clinically available and even more in development, it is crucial for clinicians to familiarize themselves with the mechanisms of action, efficacy data, and safety profiles of these treatments. In this review, we aim to summarize key findings from past and ongoing trials with anti-HER2 agents in metastatic colorectal cancer.

Characterizing the Efficacy and Safety of Chemotherapy Plus Everolimus in HER2-Negative Metastatic Breast Cancer Harboring Altered PI3K/AKT/mTOR.

The clinical outcomes of chemotherapy (CT) for the treatment of metastatic triple-negative (TN) and hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (mBC) have proven to be disappointing. The phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway, a tumor-promoting signaling cascade frequently mutated in breast cancer (BC), has been implicated in chemoresistance. In this study, our objective is to investigate the efficacy and safety of combining everolimus with chemotherapy in mBC patients exhibiting mutations in the PI3K/AKT/mTOR pathway. We conducted a retrospective analysis to characterize the efficacy, safety, and their association with clinical and molecular characteristics of metastatic lesions in 14 patients with HER2- mBC. These patients harbored at least one altered member of the PI3K/AKT/mTOR signaling pathway and were treated with a combination of a chemotherapy agent and the mTOR inhibitor everolimus (CT+EVE). The majority of patients belonged to the triple-negative (TN) subtype (9/14, 64.3%), having already undergone 2 lines of chemotherapy (CT) in the metastatic setting (11, 78.6%). These patients carried altered phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) and were administered a vinorelbine-containing regimen (10, 71.4%). The objective response rate (ORR) was 42.9%, with a disease control rate of 92.9%. The median progression-free survival (PFS) and overall survival (OS) were 5.9 (95% confidence interval (CI): 4.9-13.6) months and 14.3 (95% CI: 8.5-not reached (NR)) months, respectively. Patients with fewer prior treatment lines tended to exhibit longer PFS. OS, PFS, and ORR were comparable between hormone receptor-positive (HR+) and triple-negative breast cancer (TNBC) patients, but numerical improvements were noted in patients with a single PI3K pathway alteration compared to those with more than one alteration. Genomic alterations that surfaced upon progression on CT+EVE included cyclin dependent kinase 4 (CDK4) and epidermal growth factor receptor (EGFR) amplification, as well as neurofibromin 1 (NF1) mutation, suggesting potential mechanisms of acquired resistance. An analysis of adverse events indicated manageable toxicities. The findings of this study suggest both activity and safety for the combination of chemotherapy and the mTOR inhibitor everolimus (CT+EVE) in patients with HER2- mBC who have alterations in the PI3K pathway, particularly those who have received fewer prior chemotherapy. However, it is crucial to note that large-scale, randomized control studies are warranted to more comprehensively characterize the efficacy and safety of this combination therapy.

Detecting EGFR gene amplification using a fluorescence in situ hybridization platform based on digital microfluidics

Signal transduction mediated by epidermal growth factor receptor (EGFR) gene affects the proliferation, invasion, metastasis, and angiogenesis of tumor cells. In particular, non-small cell lung cancer (NSCLC) patients with increased in copy number of EGFR gene are often sensitive to tyrosine kinase inhibitors. Despite being the standard for detecting EGFR amplification in the clinic, fluorescence in situ hybridization (FISH) traditionally involves repetitive and complex benchtop procedures that are not only time consuming but also require well-trained personnel. To address these limitations, we develop a digital microfluidics-based FISH platform (DMF-FISH) that automatically implements FISH operations. This system mainly consists of a DMF chip for reagent operation, a heating array for temperature control and a signal processing system. With the capability of automatic droplet handling and efficient temperature control, DMF-FISH performs cell digestion, gradient elution, hybridization and DAPI staining without manual intervention. In addition to operational feasibility, DMF-FISH yields comparable performance with the benchtop FISH protocol but reducing the consumption of DNA probe by 87 % when tested with cell lines and clinical samples. These results highlight unique advantages of the fully automated DMF-FISH system and thus suggest its great potential for clinical diagnosis and personalized therapy of NSCLC.

Blockage of EGFR/AKT and mevalonate pathways synergize the antitumor effect of temozolomide by reprogramming energy metabolism in glioblastoma.

Metabolism reprogramming plays a vital role in glioblastoma (GBM) progression and recurrence by producing enough energy for highly proliferating tumor cells. In addition, metabolic reprogramming is crucial for tumor growth and immune-escape mechanisms. Epidermal growth factor receptor (EGFR) amplification and EGFR-vIII mutation are often detected in GBM cells, contributing to the malignant behavior. This study aimed to investigate the functional role of the EGFR pathway on fatty acid metabolism remodeling and energy generation. Clinical GBM specimens were selected for single-cell RNA sequencing and untargeted metabolomics analysis. A metabolism-associated RTK-fatty acid-gene signature was constructed and verified. MK-2206 and MK-803 were utilized to block the RTK pathway and mevalonate pathway induced abnormal metabolism. Energy metabolism in GBM with activated EGFR pathway was monitored. The antitumor effect of Osimertinib and Atorvastatin assisted by temozolomide (TMZ) was analyzed by an intracranial tumor model in vivo. GBM with high EGFR expression had characteristics of lipid remodeling and maintaining high cholesterol levels, supported by the single-cell RNA sequencing and metabolomics of clinical GBM samples. Inhibition of the EGFR/AKT and mevalonate pathways could remodel energy metabolism by repressing the tricarboxylic acid cycle and modulating ATP production. Mechanistically, the EGFR/AKT pathway upregulated the expressions of acyl-CoA synthetase short-chain family member 3 (ACSS3), acyl-CoA synthetase long-chain family member 3 (ACSL3), and long-chain fatty acid elongation-related gene ELOVL fatty acid elongase 2 (ELOVL2) in an NF-κB-dependent manner. Moreover, inhibition of the mevalonate pathway reduced the EGFR level on the cell membranes, thereby affecting the signal transduction of the EGFR/AKT pathway. Therefore, targeting the EGFR/AKT and mevalonate pathways enhanced the antitumor effect of TMZ in GBM cells and animal models. Our findings not only uncovered the mechanism of metabolic reprogramming in EGFR-activated GBM but also provided a combinatorial therapeutic strategy for clinical GBM management.

Dynamic contrast-enhanced MRI radiomics model predicts epidermal growth factor receptor amplification in glioblastoma, IDH-wildtype.

To develop and validate a dynamic contrast-enhanced (DCE) MRI-based radiomics model to predict epidermal growth factor receptor (EGFR) amplification in patients with glioblastoma, isocitrate dehydrogenase (IDH) wildtype. Patients with pathologically confirmed glioblastoma, IDH wildtype, from January 2015 to December 2020, with an EGFR amplification status, were included. Patients who did not undergo DCE or conventional brain MRI were excluded. Patients were categorized into training and test sets by a ratio of 7:3. DCE MRI data were used to generate volume transfer constant (Ktrans) and extracellular volume fraction (Ve) maps. Ktrans, Ve, and conventional MRI were then used to extract the radiomics features, from which the prediction models for EGFR amplification status were developed and validated. A total of 190 patients (mean age, 59.9; male, 55.3%), divided into training (n = 133) and test (n = 57) sets, were enrolled. In the test set, the radiomics model using the Ktrans map exhibited the highest area under the receiver operating characteristic curve (AUROC), 0.80 (95% confidence interval [CI], 0.65-0.95). The AUROC for the Ve map-based and conventional MRI-based models were 0.74 (95% CI, 0.58-0.90) and 0.76 (95% CI, 0.61-0.91). The DCE MRI-based radiomics model that predicts EGFR amplification in glioblastoma, IDH wildtype, was developed and validated. The MRI-based radiomics model using the Ktrans map has higher AUROC than conventional MRI.

Intratumoral thrombosis as a histological biomarker for predicting epidermal growth factor receptor alteration and poor prognosis in patients with glioblastomas.

Intratumoral thrombosis is a specific finding in glioblastomas and considered the origin of palisading necrosis. Its distribution and contribution to the glioblastoma pathophysiology and systemic thrombosis are obscure, although deep vein thrombosis is a common complication in glioblastoma cases. Clinicopathological and genetic analyses were performed on 97 glioblastoma tissue specimens to elucidate the role of thrombotic events and associated molecular abnormalities. Morphologically, intratumoral thrombosis was observed more frequently in vessels composed of single-layered CD34-positive endothelium and/or αSMA-positive pericytes in the tumor periphery, compared to microvascular proliferation with multi-channeled and pericyte-proliferating vessels in the tumor center. Intratumoral thrombosis was significantly correlated with the female sex, high preoperative D-dimer levels, and epidermal growth factor receptor (EGFR) amplification. The presence of one or more thrombi in 20 high-power fields was a predictive marker of EGFR amplification, with a sensitivity of 81.5% and specificity of 52.6%. RNA sequencing demonstrated that the group with many thrombi had higher EGFR gene expression levels than the group with few thrombi. The tumor cells invading along the vessels in the tumor periphery were positive for wild-type EGFR but negative for EGFRvIII, whereas the cells around the microvascular proliferation (MVP) in the tumor center were positive for both wild-type EGFR and EGFRvIII. Intratumoral thrombosis is an independent poor prognostic factor. Aberrant but exquisitely regulated EGFR can induce thrombosis in non-MVP vessels in the tumor invasion area and then promote palisading necrosis, followed by hypoxia, abnormal angiogenesis, and further tumor cell invasion.

SEC61G assists EGFR-amplified glioblastoma to evade immune elimination

Amplification of chromosome 7p11 (7p11) is the most common alteration in primary glioblastoma (GBM), resulting in gains of epidermal growth factor receptor (EGFR) copy number in 50 to 60% of GBM tumors. However, treatment strategies targeting EGFR have thus far failed in clinical trials, and the underlying mechanism remains largely unclear. We here demonstrate that EGFR amplification at the 7p11 locus frequently encompasses its neighboring genes and identifies SEC61G as a critical regulator facilitating GBM immune evasion and tumor growth. We found that SEC61G is always coamplified with EGFR and is highly expressed in GBM. As an essential subunit of the SEC61 translocon complex, SEC61G promotes translocation of newly translated immune checkpoint ligands (ICLs, including PD-L1, PVR, and PD-L2) into the endoplasmic reticulum and promotes their glycosylation, stabilization, and membrane presentation. Depletion of SEC61G promotes the infiltration and cytolytic activity of CD8+ T cells and thus inhibits GBM occurrence. Further, SEC61G inhibition augments the therapeutic efficiency of EGFR tyrosine kinase inhibitors in mice. Our study demonstrates a critical role of SEC61G in GBM immune evasion, which provides a compelling rationale for combination therapy of EGFR-amplified GBMs.

Understanding the molecular profiling of diffuse gliomas classification: A brief overview.

Gliomas represent almost 30% of all primary brain tumors and account for 80% of malignant primary ones. In the last two decades, significant progress has been made in understanding gliomas' molecular origin and development. These advancements have demonstrated a remarkable improvement in classification systems based on mutational markers, which contribute paramount information in addition to traditional histology-based classification. We performed a narrative review of the literature including each molecular marker described for adult diffuse gliomas used in the World Health Organization (WHO) central nervous system 5. The 2021 WHO classification of diffuse gliomas encompasses many molecular aspects considered in the latest proposed hallmarks of cancer. The outcome of patients with diffuse gliomas relies on their molecular behavior and consequently, to determine clinical outcomes for these patients, molecular profiling should be mandatory. At least, the following molecular markers are necessary for the current most accurate classification of these tumors: (1) isocitrate dehydrogenase (IDH) IDH-1 mutation, (2) 1p/19q codeletion, (3) cyclin-dependent kinase inhibitor 2A/B deletion, (4) telomerase reverse transcriptase promoter mutation, (5) α-thalassemia/ mental retardation syndrome X-linked loss, (6) epidermal growth factor receptor amplification, and (7) tumor protein P53 mutation. These molecular markers have allowed the differentiation of multiple variations of the same disease, including the differentiation of distinct molecular Grade 4 gliomas. This could imply different clinical outcomes and possibly impact targeted therapies in the years to come. Physicians face different challenging scenarios according to the clinical features of patients with gliomas. In addition to the current advances in clinical decision-making, including radiological and surgical techniques, understanding the disease's molecular pathogenesis is paramount to improving the benefits of its clinical treatments. This review aims to describe straightforwardly the most remarkable aspects of the molecular pathogenesis of diffuse gliomas.

Concurrent EGFR wild-type tongue squamous cell carcinoma and EGFR-mutant lung adenocarcinoma and response to osimertinib.

e18074 Background: Epidermal growth factor receptor (EGFR) mutation is most commonly oncogenic driver in lung adenocarcinoma with 50% incidence in Asians.Osimertinib is the third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), which has been widely used in metastatic EGFR-mutant non-small cell lung cancer (NSCLC) and has significantly improved outcomes. At present, the treatment of HNSCC mainly relies on surgery or chemoradiotherapy. EGFR is overexpressed in more than 90% of head and neck squamous cell carcinoma (HNSCC). Targeted therapy for HNSCC is mainly monoclonal antibodies, while the application of small molecule inhibitors is limited. The EGFR-TKI can only be applied in subsequent-line, when disease progression on or after platinum therapy. However, the efficacy of EGFR-TKI in patients with both NSCLC and HNSCC remains unclear. Methods: We searched all patients with EGFR-mutation metastatic non-small cell lung cancer and HNSCC who used EGFR-TKI in the Second Xiangya Hospital. Tumor sections were assessed immunohistochemically using PD-L1 and EGFR expression. EGFR amplification was detected by fluorescence in situ hybridization (FISH). We collected clinical characteristics and treatment histories for all patients including time to progression on EGFR-TKI. Time to progression on EGFR-TKI was defined as time from start of EGFR-TKI to time of radiographic RECIST progression. The efficacy and prognosis were evaluated based on the RECIST (version 1.1). Results: We found an advanced lung adenocarcinoma patient who harbored an EGFR-mutation and concurrently had tongue squamous cell carcinoma with EGFR wild-type.The tongue tumor tissue sample for EGFR expression was positive by immunohistochemistry and EGFR amplification was negative by FISH. NGS showed inactive mutation of patched1 (PTCH1) and EGFR wild-type.PET-CT scans demonstrated a partial response (PR) of the lung tumor and tongue cancer after two months of treatment of osimertinib. The lung tumor maintian partial response until now (nearly 30 months). And the tongue tumor reached the first progression- free survival (PFS) at 21 months. Conclusions: The patient with NSCLC and tongue cancer who exhibited objective response to EGFR-TKI, osimertinib monotherapy. The result indicates a clear response of tongue cancer to osimertinib and the potential for the use of osimertinib in tongue cancer. However, with the specific mechanism largely unknown, it is necessary to study further the effect of osimertinib on HNSCC.

Amivantamab and lazertinib in treatment-naïve EGFR-mutated advanced non–small-cell lung cancer (NSCLC): Long-term follow-up and ctDNA results from CHRYSALIS.

9134 Background: CHRYSALIS (NCT02609776) evaluated the combination of amivantamab (ami) and lazertinib (laz) in treatment-naïve patients (pts) with epidermal growth factor receptor ( EGFR)-mutated NSCLC. As previously reported, all 20 pts achieved a partial response (overall response rate of 100%) but interpretation of long-term outcomes was limited by the length of follow up (Cho Ann Oncol 2020;31:suppl_4, 1258O; Cho J Thorac Oncol 2022;17:S126, P1.16-01). Herein, we present long-term results from this treatment-naïve cohort. Methods: The treatment-naive cohort enrolled pts with EGFR exon 19 deletion (ex19del) or L858R mutated advanced NSCLC. All pts received 1050 mg IV ami (1400 mg if ≥80 kg) and 240 mg oral laz. Response was assessed by the investigator per RECIST v1.1. Circulating tumor DNA (ctDNA) was analyzed from plasma samples prior to initiation of treatment, at Cycle 3 Day 1, and at end of treatment (EOT). Results: Of the 20 pts enrolled in the treatment-naive cohort (median 62.5 years, 55% women, all Asian), 11 had EGFR ex19del and 9 had L858R NSCLC. As of Nov 15, 2022, the median follow-up and duration of treatment were 33.6 and 33.5 months, respectively. Ten (50%) pts were progression-free and remained on treatment, including 7 of 11 (64%) with ex19del and 3 of 9 (33%) with L858R. The median duration of response (DOR), median progression-free survival (PFS), and median overall survival (OS) were not estimable. The estimated landmark PFS rate was 85% at 12 months, 65% at 24 months, and 51% at 36 months. Of note, 2 (10%) pts were treated beyond progression. The longest ongoing pt has a duration of treatment of 37.2 months and DOR of 35.7 months. Treatment-related dose interruptions, reductions, and discontinuations of either ami and laz occurred in 7 (35%) pts, 8 (40%) pts, and 1 (5%) pt, respectively. The safety profile was consistent with prior reports, with predominantly on-target EGFR- or MET-related adverse events. Among the 10 pts who discontinued treatment, 4 submitted samples for ctDNA analysis at both baseline and EOT. There was 1 pt with new PIK3CA mutations, 1 with low-level HER2 amplification, 1 pt with a new CCNE1 and EGFR amplification, and 1 pt with no new mutations detected. Updated data on ctDNA at EOT may be available at the time of congress presentation. Conclusions: At a median duration of treatment of 33.5 months, median DOR, PFS, and OS have not been reached in treatment-naïve pts receiving ami+laz, with 50% remaining progression-free and on treatment. No new safety signals were identified. The ongoing phase 3 MARIPOSA study (NCT04487080) is further investigating ami+laz vs osimertinib vs laz in previously untreated, EGFR-mutated, advanced NSCLC. Clinical trial information: NCT02609776 .

EGFR expression and relapse in patients with melanoma receiving adjuvant PD-1-based immunotherapy.

e21566 Background: Since 2018, adjuvant immune checkpoint inhibitors (ICI) have been available for patients with resected stage III/IV melanoma. The Checkmate 238 and Keynote 054 studies showed a survival benefit in patients receiving adjuvant ICI. However, there is no validated biomarker to identify patients at high risk of relapse, despite receiving adjuvant therapy. Here we investigated resistance patterns to immune checkpoint inhibition in the adjuvant setting. Methods: In this cohort study, a discovery cohort of 30 patients from the Department of Dermatology, University Hospital Zürich, was used to evaluate resistance patterns to adjuvant ICI. A second cohort of 107 patients from the Department of Dermatology, University Hospital Tuebingen, was used to validate the findings. We measured epidermal growth factor receptor (EGFR) expression in primary tumor and metastatic tissue by immunohistochemistry and digital pathology using QuPath. The primary endpoint was relapse-free survival. Results: We included 137 patients with melanoma receiving adjuvant ICI: 63 (46%) were females, and 52 (38%) patients harbored a BRAFV600 mutation. The median follow-up was 45 and 39 months in the Zürich and Tuebingen cohorts, respectively (95% confidence interval (CI) 41.8-48.2 and 36.8-41.2, respectively). The two cohorts were homogenous in terms of patients' and tumor characteristics, except for the relapse rate, which was significantly higher in the Tuebingen cohort ( p< 0.002). 71 (52%) therapy naïve in transit or lymph node metastasis and 23 (17%) primary tumors were available to evaluate EGFR expression by immunohistochemistry and digital pathology using QuPath. Surprisingly, in both cohorts, patients with high EGFR expression in metastatic tissue had a significantly higher relapse rate than patients with low EGFR expression ( p= 0.0004 and p= 0.0168 for the Zürich and Tuebingen cohorts, respectively). EGFR expression in primary tumors did not correlate with relapse-free survival ( p= 0.7286). Next-generation sequencing revealed that EGFR expression assessed by immunohistochemistry was not associated with the presence of EGFR mutations and/or amplifications. Conclusions: Currently, there are no validated biomarkers to identify patients with melanoma at high risk of recurrence, despite receiving adjuvant ICI. We found in two independent cohorts that EGFR expression in therapy naive metastatic tissue is positively associated with relapse in patients receiving adjuvant ICI. Our data identified EGFR as a prognostic biomarker that can easily be assessed by immunohistochemistry, allowing us to stratify patients for adjuvant ICI therapy according to their risk of relapse. Stratification according to EGFR expression should be considered in future clinical trials in the adjuvant setting.

Clinical characteristics and radiological features of glioblastoma, IDH-wildtype, grade 4 with histologically lower-grade gliomas.

The 2021 World Health Organization (WHO) classification of central nervous system tumors applied molecular criteria and further integrated histological and molecular diagnosis of gliomas. This classification allows for the diagnosis of isocitrate dehydrogenase wild-type (IDHwt) glioblastoma (GBM), and WHO grade 4 with histologically lower-grade gliomas (LrGGs), even in the absence of high-grade histopathologic features, such as necrosis and/or microvascular proliferation. They contain at least one of the following molecular features: epidermal growth factor receptor amplification, chromosome 7 gain/10 loss, or telomerase reverse transcriptase promoter mutation. In the imaging features at the time of histological diagnosis, a gliomatosis cerebri growth pattern was frequently observed in these tumors. Furthermore, this growth pattern was significantly higher in IDHwt GBM, WHO grade 4, with histological grade II gliomas. Although the exact prognosis of IDHwt GBM, WHO grade 4, with histologically LGGs remains unknown, its OS was approximately 1-2years similar to that of histologically IDHwt GBM, WHO grade 4, despite histopathological features similar to IDHmut LrGGs. These findings reinforce the need for the analysis of molecular features, regardless of presenting similar clinical characteristics and imaging features to IDHmut LrGGs.

Significance of molecular diagnostics for therapeutic decision-making in recurrent glioma.

Targeted therapies have substantially improved survival in cancer patients with malignancies outside the brain. Whether in-depth analysis for molecular alterations may also offer therapeutic avenues in primary brain tumors remains unclear. We herein present our institutional experience for glioma patients discussed in our interdisciplinary molecular tumor board (MTB) implemented at the Comprehensive Cancer Center Munich (LMU). We retrospectively searched the database of the MTB for all recurrent glioma patients after previous therapy. Recommendations were based on next-generation sequencing results of individual patient's tumor tissue. Clinical and molecular information, previous therapy regimens, and outcome parameters were collected. Overall, 73 consecutive recurrent glioma patients were identified. In the median, advanced molecular testing was initiated with the third tumor recurrence. The median turnaround time between initiation of molecular profiling and MTB case discussion was 48 ± 75 days (range: 32-536 days). Targetable mutations were found for 50 recurrent glioma patients (68.5%). IDH1 mutation (27/73; 37%), epidermal growth factor receptor amplification (19/73; 26%), and NF1 mutation (8/73; 11%) were the most detected alterations and a molecular-based treatment recommendation could be made for all of them. Therapeutic recommendations were implemented in 12 cases (24%) and one-third of these heavily pretreated patients experienced clinical benefit with at least disease stabilization. In-depth molecular analysis of tumor tissue may guide targeted therapy also in brain tumor patients and considerable antitumor effects might be observed in selected cases. However, future studies to corroborate our results are needed.

Neuronal differentiation drives the antitumor activity of mitogen-activated protein kinase kinase (MEK) inhibition in glioblastoma.

Epidermal growth factor receptor (EGFR) amplification is found in nearly 40%-50% of glioblastoma cases. Several EGFR inhibitors have been tested in glioblastoma but have failed to demonstrate long-term therapeutic benefit, presumably because of acquired resistance. Targeting EGFR downstream signaling with mitogen-activated protein kinase kinase 1 and 2 (MEK1/2) inhibitors would be a more effective approach to glioblastoma treatment. We tested the therapeutic potential of MEK1/2 inhibitors in glioblastoma using 3D cultures of glioma stem-like cells (GSCs) and mouse models of glioblastoma. Several MEK inhibitors were screened in an unbiased high-throughput platform using GSCs. Cell death was evaluated using flow cytometry and Western blotting (WB) analysis. RNA-seq, real-time quantitative polymerase chain reaction, immunofluorescence, and WB analysis were used to identify and validate neuronal differentiation. Unbiased screening of multiple MEK inhibitors in GSCs showed antiproliferative and apoptotic cell death in sensitive cell lines. An RNA-seq analysis of cells treated with trametinib, a potent MEK inhibitor, revealed upregulation of neurogenesis and neuronal differentiation genes, such as achaete-scute homolog 1 (ASCL1), delta-like 3 (DLL3), and neurogenic differentiation 4 (NeuroD4). We validated the neuronal differentiation phenotypes in vitro and in vivo using selected differentiation markers (β-III-tubulin, ASCL1, DLL3, and NeuroD4). Oral treatment with trametinib in an orthotopic GSC xenograft model significantly improved animal survival, with 25%-30% of mice being long-term survivors. Our findings demonstrated that MEK1/2 inhibition promotes neuronal differentiation in glioblastoma, a potential additional mechanism of action of MEK1/2 inhibitors. Thus, MEK inhibitors could be efficacious in glioblastoma patients with activated EGFR/MAPK signaling.