EGFR-TKI Osimertinib Research Articles

Evidence from resected early-stage non-small cell lung cancer with EGFR mutation: a literature review.

Non-small cell lung cancer (NSCLC) in early-stages (I-IIIA) with epidermal growth factor receptor (EGFR) mutation may have specific epidemiological, clinical characteristics and treatment implications. This review aims to summarise the available evidence on these particularities, especially focusing on patient characteristics, treatment outcomes and safety with EGFR-tyrosine-kinase inhibitor (TKI). An exhaustive search of international bibliographic databases, as well as in abstracts of communications from major international congresses was performed for evidence related to EGFR-mutated NSCLC or early-stage NSCLC published in English before December 31st, 2023. Early-stage NSCLC with EGFR mutation presents with a variable incidence depending on geographical aspects. The clinical, radiological and molecular features differ slightly from both early-stage NSCLC without EGFR mutation and advanced NSCLC with EGFR mutation. Adjuvant treatment with the third-generation EGFR-TKI osimertinib has led to improvements in disease-free survival and overall survival (OS) in these patients, representing a practice changing and a new standard of care in clinical practice. No new safety signals have been reported with EGFR-TKI in the adjuvant setting. Clinical trials are ongoing to explore new therapeutic options in the adjuvant and neoadjuvant setting as well as the optimal duration of adjuvant osimertinib. Detection of EGFR mutation in early-stage NSCLC is an important goal due to the different characteristics and additional therapeutic options that improve patient outcomes and follow-up.

Transcriptomic Heterogeneity of EGFR-Mutant Non-Small Cell Lung Cancer Evolution Toward Small-Cell Lung Cancer.

Histologic transformation from EGFR-mutant non-small cell lung cancer (NSCLC) to small-cell lung cancer (SCLC) is a key mechanism of resistance to EGFR tyrosine kinase inhibitors (TKI). However, transcriptomic changes between NSCLC and transformed SCLC (t-SCLC) remain unexplored. We conducted whole-transcriptome analysis of 59 regions of interest through the spatial profiling of formalin-fixed, paraffin-embedded tissues obtained from 10 patients (lung adenocarcinoma, 22; combined SCLC/NSCLC, 7; and t-SCLC, 30 regions of interests). Transcriptomic profiles and differentially expressed genes were compared between pre- and post-transformed tumors. Following EGFR-TKI treatment, 93.7% (15/16) of t-SCLC components evolved into neuroendocrine-high subtypes (SCLC-A or SCLC-N). The transition to t-SCLC occurred regardless of EGFR-TKI treatment and EGFR mutational status, with a notable decrease in EGFR expression (P < 0.001) at both mRNA and protein levels. Pathway analysis revealed that gene overexpression was related to epigenetic alterations in t-SCLC. Interestingly, histone deacetylase inhibitors restored EGFR expression in SNU-2962A cells and their organoid model. The synergistic effects of third-generation EGFR-TKI osimertinib and the histone deacetylase inhibitor fimepinostat were validated in both in vitro and in vivo models. Our study demonstrated that most t-SCLC cases showed neuronal subtypes with low EGFR expression. Differentially expressed gene analysis and t-SCLC preclinical models identified an epigenetic modifier as a promising treatment strategy for t-SCLC.

Adverse Event Profile of Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors for Non-small Cell Lung Cancer: An Updated Meta-analysis.

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) remain the frontline standard of care for patients with EGFR-mutant non-small cell lung cancer. An updated toxicity profile of EGFR-TKIs proves valuable in guiding clinical decision making. This study comprehensively assessed the risk of EGFR-TKI-related adverse events (AEs) involving different systems/organs. We systematically searched PubMed, Embase, Web of Science, and Cochrane library for phase III randomized controlled trials comparing EGFR-TKI monotherapy with placebo or chemotherapy in patients with non-small cell lung cancer. The odds ratio (OR) of all-grade and high-grade adverse events (AEs) including dermatologic, gastrointestinal, hematologic, hepatic, and respiratory events was pooled for a meta-analysis. Subgroup analyses based on the control arm (placebo or chemotherapy) and individual EGFR-TKIs (erlotinib, gefitinib, afatinib, dacomitinib, and osimertinib) were conducted. Thirty-four randomized controlled trials comprising 15,887 patients were included. The pooled OR showed EGFR-TKIs were associated with a significantly increased risk of all-grade dermatologic AEs including paronychia, pruritus, rash, skin exfoliation, and skin fissures, gastrointestinal AEs including abdominal pain, diarrhea, dyspepsia, mouth ulceration, and stomatitis, hepatic AEs including elevated alanine aminotransferase and aspartate aminotransferase, and respiratory AEs including epistaxis, interstitial lung disease and rhinorrhea. Furthermore, a significantly increased risk of high-grade rash (OR 7.83, 95% confidence interval [CI] 5.11, 12.00), diarrhea (OR 2.10, 95% CI 1.44, 3.05), elevated alanine aminotransferase (OR 3.93, 95% CI 1.71, 9.03), elevated aspartate aminotransferase (OR 3.22, 95% CI 1.05, 9.92) and interstitial lung disease (OR 2.35, 95% CI 1.38, 4.01) was observed in patients receiving EGFR-TKIs. When stratified by individual EGFR-TKIs, gefitinib showed a significant association with all-grade and high-grade hepatotoxicity and interstitial lung disease. Epidermal growth factor receptor tyrosine kinase inhibitors were associated with a significantly increased risk of various types of AEs. Clinicians should be vigilant about the risks of these EGFR-TKI-related AEs, particularly for severe hepatotoxicity and interstitial lung disease, to facilitate early detection and proper management.

Combination of betulinic acid and EGFR-TKIs exerts synergistic anti-tumor effects against wild-type EGFR NSCLC by inducing autophagy-related cell death via EGFR signaling pathway

BackgroundEpidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of lung cancer patients with mutated EGFR. However, the efficacy of EGFR-TKIs in wild-type EGFR tumors has been shown to be marginal. Methods that can sensitize EGFR-TKIs to EGFR wild-type NSCLC remain rare. Hence, we determined whether combination treatment can maximize the therapeutic efficacy of EGFR-TKIs.MethodsWe established a focused drug screening system to investigate candidates for overcoming the intrinsic resistance of wild-type EGFR NSCLC to EGFR-TKIs. Molecular docking assays and western blotting were used to identify the binding mode and blocking effect of the candidate compounds. Proliferation assays, analyses of drug interactions, colony formation assays, flow cytometry and nude mice xenograft models were used to determine the effects and investigate the molecular mechanism of the combination treatment.ResultsBetulinic acid (BA) is effective at targeting EGFR and synergizes with EGFR-TKIs (gefitinib and osimertinib) preferentially against wild-type EGFR. BA showed inhibitory activity due to its interaction with the ATP-binding pocket of EGFR and dramatically enhanced the suppressive effects of EGFR-TKIs by blocking EGFR and modulating the EGFR-ATK-mTOR axis. Mechanistic studies revealed that the combination strategy activated EGFR-induced autophagic cell death and that the EGFR-AKT-mTOR signaling pathway was essential for completing autophagy and cell cycle arrest. Activation of the mTOR pathway or blockade of autophagy by specific chemical agents markedly attenuated the effect of cell cycle arrest. In vivo administration of the combination treatment caused marked tumor regression in the A549 xenografts.ConclusionsBA is a potential wild-type EGFR inhibitor that plays a critical role in sensitizing EGFR-TKI activity. BA combined with an EGFR-TKI effectively suppressed the proliferation and survival of intrinsically resistant lung cancer cells via the inhibition of EGFR as well as the induction of autophagy-related cell death, indicating that BA combined with an EGFR-TKI may be a potential therapeutic strategy for overcoming the primary resistance of wild-type EGFR-positive lung cancers.Graphical abstract

Abstract 1967: IN-119873, the next-generation allosteric EGFR TKI, a potent and highly selective EGFR L858R for the treatment of osimertinib-resistant NSCLC

Abstract EGFR mutations occur in approximately 50% of Asian patients and 20% of Caucasian patients with non-small cell lung cancer (NSCLC). The EGFR L858R mutation constitutes approximately half of the EGFR-mutated patients, and despite receiving first-line or second-line treatment with the 3rd generation EGFR TKI osimertinib, they continue to exhibit a poor prognosis. According to real-world analysis, the leading resistance mechanism to osimertinib is identified as EGFR C797S mutation. Furthermore, osimertinib is still associated with gastrointestinal and skin toxicity, despite its improved selectivity for EGFR WT compared to 1st-generation EGFR TKIs. Here, we show that IN-119873 can overcome C797S-mediated acquired resistance based on the results obtained by various in vitro and in vivo NSCLC models. IN-119873 binds to an EGFR allosteric site separate from the ATP-binding site with a remarkable preference for highly mutant-selective inhibition. It effectively targets EGFR L858R activating mutations while sparing the inhibition of EGFR WT, which sets it apart from ATP competitive inhibitors. Moreover, oral administration of IN-119873 showed excellent anti-tumor efficacy in a dose-dependent manner in a diverse of osimertinib-resistant CDX and PDX models. IN-119873 also demonstrated favorable blood-brain-barrier penetration with promising intracranial efficacy in the H1975-luc brain metastasis model both mono or in combination with osimertinib. As a selective, orally available, and CNS-penetrable next-generation allosteric EGFR-TKI, IN-119873 is currently undergoing IND-enabling studies and has the potential to demonstrate activity in both first-line and resistance settings, either as a monotherapy or in combination with 3rd generation EGFR TKI. Citation Format: Jong Ryoul Choi, Daseul Yoon, Seo Hyun Kim, Do Gyeong Kim, Seock Yong Kang, Seong-Il Choi, Somyi Park, Hyun Kyung Lee, Donghyun Kim, Ju Hyun Lee, Hye-Jung Kim, Bong Tae Kim. IN-119873, the next-generation allosteric EGFR TKI, a potent and highly selective EGFR L858R for the treatment of osimertinib-resistant NSCLC [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 1967.

Abstract 3348: Identification of circSPINT2 as a tumor suppressive circular RNA sensitizing lung cancer to 3rd generation EGFR-TKI treatment

Abstract Introduction: Lung cancer remains a high incidence and mortality globally. Adenocarcinoma is the most common type of lung cancer with around 50% of patients in Asia expressing mutated EGFR, which makes EGFR an effective therapeutic target to treat lung adenocarcinoma (LAC). Unfortunately, resistance to EGFR-TKI often occurs in patients through either dynamic EGFR mutation, driver oncogenic pathway shift, or transdifferentiating to evade EGFR-TKI treatment. circRNAs are a type of RNA molecule with a circular shape. Their importance in several biological processes and disease progression was intensively studied recently, and have emerged as promising diagnostic, prognostic, and monitoring biomarkers for diseases like cancer. CircRNAs’ unique circular structure and resistance to degradation make them robust candidates for non-invasive diagnostics of cancers. Aims: This study aimed to identify and investigate the involvement of a novel circular RNA (circSPINT2) in acquired resistance against the 3rd generation EGFR-TKI Osimertinib. Materials &amp; Methods: Comparative circRNA sequencing (circRNA-Seq), qRT-PCR, sanger sequencing, and RNase R treatment were applied to identify and verify the identity of Osimertinib-resistance-related circRNA. Biotinylated circRNA pull-down assay, miRNA-seq, and in-silico analysis were employed to delineate the downstream miRNA-mRNA regulatory axis. Osimertinib-resistant mouse xenograft model was established to explore the molecular mechanisms associated with both circSPINT2 and Osimertinib resistance. Results: We identified circSPINT2 as particularly downregulated in Osimertinib-resistant cell lines (OR) using circRNA-Seq. Overexpression of circSPINT2 in resistant cells increased cellular sensitivity to Osimertinib, whereas knockdown of circSPINT2 conferred Osimertinib resistance in parental cells. The circSPINT2-dependent regulation of Osimertinib sensitivity is mediated through modulating apoptosis. In-vitro analysis indicated high circSPINT2 increased tumor suppressor RBP1 expression by sequestering oncogenic hsa-miR-1296 further improving Osimertinib sensitivity. Molecular and histologic analysis of subcutaneous xenograft tumors corroborated our in-vitro results. Conclusion: Our study demonstrated circSPINT2 functions as a tumor suppressor, improving Osimertinib sensitivity via the hsa-miR-1296/RBP1 axis. circSPINT2 may serve as a prognostic and cancer biomarker to monitor Osimertinib resistance in LAC patients. Citation Format: Mong-Lien (Lotus) Wang, Shih-Hwa Shiou, Yi-Chen Chen, Ming-Long Tsai, Nalini Devi Verusingam, Alan Han-Kiat Ong. Identification of circSPINT2 as a tumor suppressive circular RNA sensitizing lung cancer to 3rd generation EGFR-TKI treatment [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 3348.

Abstract 6484: Overcoming resistance to EGFR-TKI in NSCLC by simultaneously inhibition of anti-apoptotic proteins

Abstract Lung cancer is the second most common cancer worldwide with 1.8 million deaths in 2020 being the leading cause of cancer related death. With 86% of cases, non-small cell lung cancer (NSCLC) is the most prominent subtype. The survival rate improved over the past 20 years by application of targeted therapies. Driver mutations in protein kinases such as the epidermal growth factor receptor (EGFR) are frequent and have evolved as therapeutic targets in anti-cancer therapy. Inhibitors of receptor tyrosine kinase (RTKIs), prominently EGFR-TKIs, are effective in anti-cancer therapy but tumor evolution inevitably generates resistance. Thus, strategies for the treatment of patients with acquired resistance to RTKIs remains an urgent need. Resistance in solid tumors is overcome by a combination of bortezomib with the BH3-mimetic ABT-199 (Muenchow et al. 2020). Also, overcoming ALK-TKI resistance in NSCLC was described by Tanimoto et al. (2021) by proteasome inhibiton that mediates induction of NOXA. Furthermore, the novel described BCL-2 independent activity of ABT-199 to transactivate NOXA expression (Weller et al. 2022) represents a generally active principle by combining drugs with independent mechanism of action. We hypothesize, that combined treatment of EGFR-TKI Osimertinib (OSI) with BH3-mimetics enhances sensitivity to apoptosis induction. To explore this hypothesis, we investigated cell death induction by combined administration of OSI and BH3-mimetics or PIs in NSCLC differing in their mutational status. In addition, we analyzed the expression of BCL-2 family proteins and their relevance and regulation during RTKI-induced cell death by RNA sequencing and Western Blot. These analyses will be performed in cellular model systems of NSCLC with specific resistance mediating mutations of EGFR or activated parallel survival pathways. We found that BCL-2 inhibitors enhance efficacy of OSI in NSCLC, resulting in synergistic cell death induction. Additionally, the sensitivity to BCL-2 inhibitors tends to increase in OSI-resistant NSCLC. Western Blot analysis and RNA sequencing data of OSI-resistant NSCLC identified BCL-2 overexpression and an EMT signature as resistance-mediating mechanisms, which can be overcome by combination of OSI with BCL-2 inhibitors. Indeed, our data suggest that combination of OSI with BCL-2 inhibitors disrupts resistance to OSI in NSCLC. We propose that BCL-2 inhibitors sensitize OSI-resistant NSCLC to effectively induce cell death. Thus, studying the molecular mechanism of synergistic efficacy of RTKI/BCL-2 inhibitor combination therapies, should prompt future efforts in the clinical evaluation of combinatorial regimens. We hypothesize that a general therapeutic concept which relies on simultaneous blocking of driver mutations and survival-promoting BCL-2 proteins represents a generally active principle of a tumor-agnostic mechanism of action. Citation Format: Sandra Weller, Tobias Beigl, Frank Essmann, Annika Harsch, Hans-Georg Kopp, Tom Ekstrom. Overcoming resistance to EGFR-TKI in NSCLC by simultaneously inhibition of anti-apoptotic proteins [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 6484.

TP53 gain-of-function mutations promote osimertinib resistance via TNF-α–NF-κB signaling in EGFR-mutated lung cancer

EGFR tyrosine kinase inhibitors (TKIs) are effective against EGFR-mutated lung cancer, but tumors eventually develop resistance to these drugs. Although TP53 gain-of-function (GOF) mutations promote carcinogenesis, their effect on EGFR-TKI efficacy has remained unclear. We here established EGFR-mutated lung cancer cell lines that express wild-type (WT) or various mutant p53 proteins with CRISPR-Cas9 technology and found that TP53-GOF mutations promote early development of resistance to the EGFR-TKI osimertinib associated with sustained activation of ERK and expression of c-Myc. Gene expression analysis revealed that osimertinib activates TNF-α–NF-κB signaling specifically in TP53-GOF mutant cells. In such cells, osimertinib promoted interaction of p53 with the NF-κB subunit p65, translocation of the resulting complex to the nucleus and its binding to the TNF promoter, and TNF-α production. Concurrent treatment of TP53-GOF mutant cells with the TNF-α inhibitor infliximab suppressed acquisition of osimertinib resistance as well as restored osimertinib sensitivity in resistant cells in association with attenuation of ERK activation and c-Myc expression. Our findings indicate that induction of TNF-α expression by osimertinib in TP53-GOF mutant cells contributes to the early development of osimertinib resistance, and that TNF-α inhibition may therefore be an effective strategy to overcome such resistance in EGFR-mutant lung cancer with TP53-GOF mutations.

Sialyltransferase ST3GAL4 confers osimertinib resistance and offers strategies to overcome resistance in non-small cell lung cancer

The third-generation EGFR-TKI osimertinib is widely used in EGFR-mutated positive non-small cell lung cancer (NSCLC) patients, but drug resistance is inevitable. The currently known mechanisms only explain resistance in a small proportion of patients. For most patients, the mechanism of osimertinib resistance is still unclear, especially for EGFR-independent resistance. Herein, we thoroughly investigated the novel mechanism of osimertinib resistance and treatment strategies. We identified that ST3GAL4, a sialyltransferase, catalyzes terminal glycan sialylation of receptor protein tyrosine kinases, which induces acquired resistance to osimertinib in vitro and in vivo. In addition, ST3GAL4 is generally overexpressed in osimertinib-resistant patients with unknown resistance mechanisms. ST3GAL4 modifies MET glycosylation on N785 with sialylation, which antagonizes K48-related ubiquitin-dependent MET degradation and subsequently activates MET and its downstream proliferation signaling pathways. Meanwhile, ST3GAL4 knockdown or inhibition by brigatinib resensitizes resistant non-small cell lung cancer cells to osimertinib in vitro and in vivo This study suggests that ST3GAL4 can induce acquired resistance to osimertinib, which may be an important EGFR-independent resistance mechanism Furthermore, targeting ST3GAL4 with brigatinib provides new strategies to overcome osimertinib resistance.

Discovery of a Novel Potent EGFR Inhibitor Against EGFR Activating Mutations and On-Target Resistance in NSCLC.

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) serve as the standard first-line therapy for EGFR-mutated non-small cell lung cancer (NSCLC). Despite the sustained clinical benefits achieved through optimal EGFR-TKI treatments, including the third-generation EGFR-TKI osimertinib, resistance inevitably develops. Currently, there are no targeted therapeutic options available postprogression on osimertinib. Here, we assessed the preclinical efficacy of BI-4732, a novel fourth-generation EGFR-TKI, using patient-derived preclinical models reflecting various clinical scenarios. The antitumor activity of BI-4732 was evaluated using Ba/F3 cells and patient-derived cell/organoid/xenograft models with diverse EGFR mutations. Intracranial antitumor activity of BI-4732 was evaluated in a brain-metastasis mouse model. We demonstrated the remarkable antitumor efficacy of BI-4732 as a single agent in various patient-derived models with EGFR_C797S-mediated osimertinib resistance. Moreover, BI-4732 exhibited activity comparable to osimertinib in inhibiting EGFR-activating (E19del and L858R) and T790M mutations. In a combination treatment strategy with osimertinib, BI-4732 exhibited a synergistic effect at significantly lower concentrations than those used in monotherapy. Importantly, BI-4732 displayed potent antitumor activity in an intracranial model, with low efflux at the blood-brain barrier. Our findings highlight the potential of BI-4732, a selective EGFR-TKI with high blood-brain barrier penetration, targeting a broad range of EGFR mutations, including C797S, warranting clinical development.

The third-generation EGFR TKI osimertinib could be a promising neoadjuvant therapy in patients with resectable EGFR-mutant NSCLC

The third-generation EGFR TKI osimertinib could be a promising neoadjuvant therapy in patients with resectable EGFR-mutant NSCLC

BLU-945, a potent and selective next-generation EGFR TKI, has antitumor activity in models of osimertinib-resistant non-small-cell lung cancer.

Despite the availability of several epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), most patients with non-small-cell lung cancer (NSCLC) eventually develop resistance to these agents. Notably, EGFR_C797S mutations confer resistance to the third-generation EGFR-TKI osimertinib and no approved post-osimertinib targeted pharmacology options are currently available. BLU-945 is a novel, reversible, and orally available next-generation EGFR-TKI that selectively targets EGFR-activating (EGFRm) and resistance mutations (including EGFR_C797S) with nanomolar potency while sparing wild-type EGFR in vitro. In vitro activity of BLU-945 as a single agent and in combination with osimertinib was tested in engineered EGFR-mutant cell lines as well as patient-derived cells and patient-derived organoids. In vivo activity was evaluated in osimertinib-resistant patient-derived xenograft mouse models. Three patient cases from the global, first-in-human, phase I/II SYMPHONY trial (NCT04862780) demonstrating the clinical efficacy of BLU-945 were reported. In vitro BLU-945 demonstrated inhibited cell viability and growth of EGFR-mutant/osimertinib-resistant cell lines. BLU-945 demonstrated in vivo tumor shrinkage in osimertinib-resistant models of NSCLC (osimertinib second line: EGFR_L858R/C797S and third line: EGFR_ex19del/T790M/C797S and L858R/T790M/C797S) both as monotherapy and in combination with osimertinib. BLU-945 also demonstrated tumor shrinkage in patients from the SYMPHONY trial. Our findings demonstrate the preclinical and early clinical activity of BLU-945 in EGFRm NSCLC progressing on previous EGFR-TKIs.

YTHDF3 Modulates EGFR/ATK/ERK/p21 Signaling Axis to Promote Cancer Progression and Osimertinib Resistance of Glioblastoma Cells.

Despite recent advances in EGFR-tyrosine kinase inhibitor (TKI) drugs for glioblastoma multiforme (GBM), intrinsic EGFR alterations in GBM have resulted in drug resistance and unsatisfactory clinical development of EGFR-TKIs. Determining the unknown mechanisms underlying EGFR-TKI drug resistance is an urgent, but unmet, medical need for GBM. Although several m6A RNA methylation regulators, such as reader YTHDF1/2, were recently predicted to be related to GBM recurrence, none was associated with resistance to the 3rd generation EGFR-TKI osimertinib. Osimertinib-resistant GBM cells (U87OSR) were established to ascertain the correlation between m6A expression and osimertinib resistance, prior to systemic analyses on m6A writers, erasers, and readers. YTHDF3-silencing was employed to reveal changes in IC50, cellular migration, cancer stemness, and p21-guided senescence in U87OSR cells. Signaling pathways and an in vivo xenograft model of U87OSR cells were investigated to delineate the influence of osimertinib-resistance and elevated YTHDF3 expression. YTHDF3 played a crucial role in inducing cellular proliferation, migration, and stemness in U87OSR GBM cells. Importantly, silencing of YTHDF3 markedly reduced the activation of certain signaling pathways, including EGFR- or ITGA7- AKT, and ERK in U87OSR cells. Our study also revealed the oncogenic function of YTHDF3 in inducing senescence escape via p21 down-regulation. In contrast, silencing of YTHDF3 resulted in increased p21 expression, senescence, and suppressed tumor growth in our osimertinib-resistant preclinical model. Overall, our research underscores the novel potential of YTHDF3 as a new pharmacological target in GBM treatment, specifically for patients with osimertinib-resistant or refractory tumors.

P2.09-38 MRI Radiomics Approach to Predict the Intracranial Efficacy of the Third Generation EGFR-TKI Osimertinib in NSCLC Patients with Brain Metastases

P2.09-38 MRI Radiomics Approach to Predict the Intracranial Efficacy of the Third Generation EGFR-TKI Osimertinib in NSCLC Patients with Brain Metastases

CDK4/6 signaling attenuates the effect of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors in EGFR-mutant non-small cell lung cancer.

Epidermal growth factor receptor (EGFR) mutations, such as exon 19 deletion and exon 21 L858R, are driver oncogenes of non-small cell lung cancer (NSCLC), with EGFR tyrosine kinase inhibitors (TKIs) being effective against EGFR-mutant NSCLC. However, the efficacy of EGFR-TKIs is transient and eventually leads to acquired resistance. Herein, we focused on the significance of cell cycle factors as a mechanism to attenuate the effect of EGFR-TKIs in EGFR-mutant NSCLC before the emergence of acquired resistance. Using several EGFR-mutant cell lines, we investigated the significance of cell cycle factors to attenuate the effect of EGFR-TKIs in EGFR-mutant NSCLC. In several EGFR-mutant cell lines, certain cancer cells continued to proliferate without EGFR signaling, and the cell cycle regulator retinoblastoma protein (RB) was not completely dephosphorylated. Further inhibition of phosphorylated RB with cyclin-dependent kinase (CDK) 4/6 inhibitors, combined with the EGFR-TKI osimertinib, enhanced G0/G1 cell cycle accumulation and growth inhibition of the EGFR-mutant NSCLC in both in vitro and in vivo models. Furthermore, residual RB phosphorylation without EGFR signaling was maintained by extracellular signal-regulated kinase (ERK) signaling, and the ERK inhibition pathway showed further RB dephosphorylation. Our study demonstrated that the CDK4/6-RB signal axis, maintained by the MAPK pathway, attenuates the efficacy of EGFR-TKIs in EGFR-mutant NSCLC, and targeting CDK4/6 enhances this efficacy. Thus, combining CDK4/6 inhibitors and EGFR-TKI could be a novel treatment strategy for TKI-naïve EGFR-mutant NSCLC.

Epigallocatechin gallate circumvents drug-induced resistance in non-small-cell lung cancer by modulating glucose metabolism and AMPK/AKT/MAPK axis.

Upon prolonged use of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in non-small-cell lung cancer (NSCLC), acquired drug resistance inevitably occurs. This study investigates the combined use of EGFR-TKIs (gefitinib or osimertinib) with epigallocatechin gallate (EGCG) to overcome acquired drug resistance in NSCLC models. The in vitro antiproliferative effects of EGFR-TKIs and EGCG combination in EGFR-mutant parental and resistant cell lines were evaluated. The in vivo efficacy of the combination was assessed in xenograft mouse models derived from EGFR-TKI-resistant NSCLC cells. We found that the combined use of EGFR-TKIs and EGCG significantly reversed the Warburg effect by suppressing glycolysis while boosting mitochondrial respiration, which was accompanied by increased cellular ROS and decreased lactate secretion. The combination effectively activated the AMPK pathway while inhibited both ERK/MAPK and AKT/mTOR pathways, leading to cell cycle arrest and apoptosis, particularly in drug-resistant NSCLC cells. The in vivo results obtained from mouse tumor xenograft model confirmed that EGCG effectively overcame osimertinib resistance. This study revealed that EGCG suppressed cancer bypass survival signaling and altered cancer metabolic profiles, which is a promising anticancer adjuvant of EGFR-TKIs to overcome acquired drug resistance in NSCLC.

Prognostic impact of baseline circulating extracellular vesicles (BCEVs) in the setting of patients with advanced non-small cell lung cancer (ANSCLC) eligible for first line treatment with osimertinib.

e14553 Background: In the liquid biopsy era, the interrogation of extracellular vesicles (EVs) content might be complementary for cancer prognostication and response assessment. In this explorative study, we aimed to describe whether the serial characterization of BCEVs plasma tumor-derived EVs could longitudinally reflect response and resistance to available first-line treatments, investigating the potential to predict clinical outcomes in patients with advanced NSCLC (aNSCLC). Methods: From 2020/02 to 2022/05, 27 treatment-naïve patients with aNSCLC (stageIIIB/IV), eligible for first-line treatment with an EGFRTKI (Osimertinib) or ICIs (e.g. Pembrolizumab ± platinum‐based chemotherapy) based on the predictive molecular pathology, were enrolled. Blood samples (∼5 mL) were collected into K2EDTA tubes early in the morning with fasting condition. We isolated EVs from 2 ml of plasma using exo-Easy Maxi Kit (Qiagen-USA). EVs’s size and distribution was determine by use of Dynamic Light Scattering method (DLS). Besides a Bradford assay (cfEV) for the indirect quantification of EV amount based on EVs proteins content was performed. According to the radiologic response, EV analyses were evaluated in patients with available plasma samples from baseline (T0) to the first radiologic evaluation of disease within 12 weeks (T1). Results: From 2020/02 to 2022/05, 27treatment-naïve patients with aNSCLC (stageIIIB/IV), eligible for first-line treatment with an EGFRTKI (Osimertinib) or ICIs (e.g. Pembrolizumab ± platinum‐based chemotherapy) based on the predictive molecular pathology, were enrolled. Blood samples (∼5 mL) were collected into K2EDTA tubes early in the morning with fasting condition. We isolated EVs from 2 ml of plasma using exo-Easy Maxi Kit (Qiagen-USA). EVs’s size and distribution was determine by use of Dynamic Light Scattering method (DLS). Besides a Bradford assay (cfEV) for the indirect quantification of EV amount based on EVs proteins content was performed. According to the radiologic response, EV analyses were evaluated in patients with available plasma samples from baseline (T0) to the first radiologic evaluation of disease within 12 weeks (T1). Conclusions: This real-world study confirmed the in vivo feasibility of isolating and characterizing BCEVs via DLS and Bradford assay from the plasma of patients with ANSCLC. The quantitative changes of the plasma EVs correlated with survival in the real-time monitoring of such first-line patients, mostly in the oncogene-addicted population receiving osimertinib.

Osimertinib for EGFR-Mutant Non-Small-Cell Lung Cancer Central Nervous System Metastases: Current Evidence and Future Perspectives on Therapeutic Strategies.

Central nervous system (CNS) metastases are common in non-small-cell lung cancer (NSCLC) and associated with poor prognosis and high disease burden. Effective options are needed to treat CNS metastases, and delay or prevent their formation. For epidermal growth factor receptor mutation-positive (EGFRm) advanced NSCLC and brain metastases, upfront EGFR-tyrosine kinase inhibitors (TKIs) are recommended by the joint European Association of Neuro-Oncology-European Society for Medical Oncology and experts. While early-generation EGFR-TKIs have limited CNS efficacy, the third-generation, irreversible, EGFR-TKI osimertinib has potent efficacy in NSCLC CNS metastases. This review discusses the CNS data of osimertinib in the context of therapeutic strategies and future prospects based on expert review of published literature and relevant clinical, real-world, and ongoing studies in this setting. Osimertinib penetrates the blood-brain barrier and achieves greater exposure in the brain compared with other EGFR-TKIs. Osimertinib has demonstrated CNS efficacy, including in leptomeningeal metastases, in EGFRm advanced disease. In EGFRm stage IB-IIIA NSCLC, adjuvant osimertinib reduced CNS disease recurrence versus placebo. The burden and poor prognosis of CNS metastases necessitate more therapeutic options for their management and reduced risk of recurrence in patients with EGFRm NSCLC. Clinical studies are ongoing in advanced disease to investigate osimertinib combinations with chemotherapy/radiation therapy and optimal treatment post-CNS progression with osimertinib. Further prospective research evaluating treatments using CNS-specific endpoints and evaluating CNS resistance is needed to improve outcomes for patients with CNS metastases.

364P Tepotinib with an EGFR-tyrosine kinase inhibitor (TKI) in patients with EGFR-mutant MET-amplified NSCLC: A case series

MET amplification (METamp) is a mechanism of acquired resistance to EGFR-TKIs. In the INSIGHT trial (NCT01982955), in patients with EGFR-mutant METamp NSCLC and EGFR-TKI resistance, tepotinib (a potent, highly selective MET-TKI) plus gefitinib (EGFR-TKI) improved outcomes in comparison with chemotherapy. We present a case series highlighting the clinical activity of tepotinib plus an EGFR-TKI (gefitinib and/or osimertinib) in patients with EGFR-mutant METamp NSCLC.

ODP359 Thyrotropin secreting pituitary microadenoma and lung adenocarcinoma treated with epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) Erlotinib and Osimertinib: a case report

Abstract Background Thyrotropin secreting pituitary adenoma (TSHoma) of the pituitary specific transcription factor-1 (PIT-1) lineage, is the rarest subtype of pituitary neuroendocrine tumours (pitNETs). TSHomas must be discriminated from primary hyperthyroidism and can cause morbidity through thyrotoxicosis or local mass effect. Serum alpha-subunit level may be used as a marker of tumour activity, as 50-85% of TSHoma patients have high serum alpha-subunit levels. First line treatment is surgical resection of the tumour. Medical therapy with somatostatin analogues or radiotherapy may be used for tumour control. Epidermal growth factor receptor (EGFR) expression has been demonstrated in pitNETs including corticotrophs, gonadotrophs, lactotrophs and somatotrophs. EGFR inhibiting agent, Lapatinib, has been investigated for treatment of prolactinomas and EGFR expression is implicated in tumorigenesis of corticotrophs. EGFR targeting tyrosine kinase inhibitors (TKIs) can be used first line to treat metastatic adenocarcinoma of the lung harbouring activating EGFR mutations. Case Report A non-smoking 53-year-old male of Middle Eastern heritage was seen in clinic with secondary hyperthyroidism on a background of metastatic adenocarcinoma of the lung and hypertension. The patient had no symptoms of hyperthyroidism and had no personal or family history of thyroid dysfunction. No new headaches or visual disturbance were reported. Physical exam showed brisk reflexes, no specific signs of hyperthyroidism or thyromegaly were seen. Thyroid function tests demonstrated a persistently elevated TSH 5.1mIU/L (0.4-4. 0), T4 21.8pmol/L (9-19) and T3 6.4pmol/L (2.6-6. 0) with negative anti- thyroid receptor, thyroperoxidase and thyroglobulin antibodies. Ultrasound of the thyroid was unremarkable. MRI revealed a well-circumscribed left anterior pituitary lesion of 5.4×6.8mm in size. Surgery was deferred as 3 months prior, he was diagnosed with stage 4 intrapulmonary adenocarcinoma of the lung with an exon-19 deletion mutation in the EGFR gene. He received stereotactic radiotherapy and EGFR targeted therapy using 100mg of Erlotinib daily, which increased to 200mg 6 months later. After 1 year of therapy, his adenocarcinoma progressed and he was transitioned to the 3 rd generation EGFR-TKI Osimertinib. Instead of undergoing the risk of pituitary surgery, a trial of EGFR therapy for its pleiotropic pituitary adenoma effects was decided. During the EGFR-TKI treatment period, alpha subunit levels have remained stable and serial MRI imaging at 1 year showed no interval pituitary adenoma growth. Conclusion This is a rare case of TSHoma identified during treatment of lung cancer with EGFR-TKIs. EGFR signalling is implicated in prolactinomas and corticotrophs though there is a paucity of data regarding TSHomas. To date, our patient has achieved radiological and biochemical stability in his TSHoma, with hyperthyroidism control on EGFR-TKI therapy, suggestive of a therapeutic benefit from EGFR signal blockade. Further studies are needed in larger cohorts to quantify EGFR expression in TSHomas and evaluate its possible role in pathogenesis. Presentation: No date and time listed