Epidermal Growth Factor Receptor TKIs Research Articles

Abstract 5831: The TLE1 transcriptional and epigenetic machinery contributes to EGFR targeted therapy resistance in human lung adenocarcinoma

Abstract In human lung adenocarcinoma that carry Epidermal Growth Factor Receptor (EGFR) sensitizing mutations, targeting the EGFR pathway with the use of EGFR tyrosine kinase inhibitors (EGFR-TKIs) has emerged as a promising therapeutic strategy providing initial clinical benefit to many patients. Unfortunately, resistance to EGFR-TKIs eventually develops leading to disease progression. In addition to genetic mutations, transcriptional and epigenetic mediated changes in gene expression remain an important mechanism contributing to EGFR-TKI resistance. Here, we report a novel function of the transcriptional corepressor Transducin-Like Enhancer of Split-1 (TLE1) in mediating EGFR-TKI resistance in EGFR mutant LUAD cells through its survival promoting gene transcriptional program. In EGFR mutant, EGFR TKI sensitive LUAD cells, sole activation of the TLE1 nuclear function attenuates EGFR TKI sensitivity with concomittant reduction of EGFR-TKI-mediated apoptosis. Conversely, downregulation of endogenous TLE1 expression via siRNAs/shRNAs and deletion of TLE1 gene via CRISPR-Cas9 in EGFR-mutant, EGFR-TKI resistant cells partially restore EGFR-TKI sensitivity via induction of EGFR-TKI apoptosis. Mechanistically, the anti-apoptosis promoting gene transcriptional program of TLE1 is dependent on its functional interaction with the transcriptional repressor HES-1, a downstream Notch target which has been associated with relapse in LUAD patients following EGFR-TKI treatment. Collectively, these studies indicate the TLE1 corepressor as a determinant of resistance to EGFR targeted therapy and raise the possibility that inhibiting TLE1 nuclear function may serve as an adjuct therapy to circumvent EGFR-TKI resistance. Citation Format: Hector Ramos Biliran, Xin Yao, Nasir Roberts, Prince Iheukwumere, Renwei Chen, Ma. Carmela Dela Cruz. The TLE1 transcriptional and epigenetic machinery contributes to EGFR targeted therapy resistance in human lung adenocarcinoma [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 5831.

Abstract 3290: FTO mediates tumor growth and resistance to erlotinib in NSCLC

Abstract Lung cancer, among the most common cancer types, ranks first in cancer associated deaths. Nearly 85% of the lung cancer cases are non-small cell lung cancer (NSCLC). Epidermal growth factor receptor (EGFR), an established marker for NSCLC, is frequently overexpressed on the cell surface. Amplifying mutations often render these receptors activated in a ligand independent manner, therefore, therapies such as erlotinib, an EGFR tyrosine kinase inhibitor (EGFR-TKI), target these activating mutations and inhibit tumor growth. Nevertheless, patients acquire resistance to EGFR TKI within 9-14 months of treatment. Recent studies show that fat mass and obesity- associated (FTO) gene, initially identified to increase the body mass index, plays a major role in cancer development and acquired therapy resistance in several cancer types. FTO demethylates m6A mRNA and modulates tumorigenesis, and drug resistance. In this study, we explored the functions of FTO in EGFR TKI resistance in NSCLC. To study the expression of FTO in erlotinib resistant cells, we used wildtype-EGFR NSCLC cell lines (H2170, H358) and mutant EGFR NSCLC cell lines (H1975, PC9) that were rendered resistant to erlotinib. Our RT-qPCR results demonstrated that FTO was upregulated by 1.7-3.0 fold in erlotinib resistant H2170, H358, PC9 and H1975 cells. FTO protein was upregulated by 1.3-1.6 fold as seen by western blotting, and by 1.7 to 2.6 fold in the nucleus of erlotinib resistant H1975, H2170 and PC9 cell lines by immunofluorescence. Furthermore, we investigated FTO inhibition with Dac51 (FTOi) on cell viability and cell migration properties. MTT cell viability assay showed a 9-17% decrease in cell viability when treated with a combination of Dac51 and erlotinib compared to Dac51 alone in erlotinib resistant H2170 and PC9 cells, respectively. The combinatory treatment showed an additive effect compared to the Dac51 and erlotinib treatments alone. Wound healing assay revealed an 18% open wound area after 48-hour treatment with both Dac51 and erlotinib compared to 0.1% after treatment with erlotinib alone in erlotinib resistant H2170 cells. To evaluate the effect of siRNA mediated FTO (siFTO) knockdown on cell viability and energy metabolism, MTT and luciferase assays were performed. MTT assay showed a 21-28% decrease in viability in erlotinib resistant H1975, H2170, PC9 cells, demonstrating increase in the erlotinib efficacy, as compared to the mock siRNA treatment. Luciferase assay showed an inverse relationship between the FTO and ATP, where the latter was upregulated by 1.3 to 3.4 folds in erlotinib resistant H1975, H2170 and PC9 cells, when treated with siFTO, suggesting its involvement in the energy requirements of the NSCLC cells. In conclusion, our study suggests FTO was upregulated in erlotinib resistant NSCLC cells on both the gene and protein levels. FTO could mediate resistance to EGFR TKI possibly through cell proliferation and migration and help with prognosis of NSCLC patients. Citation Format: Aayush Rastogi, Rong Qiu, Neelu Puri. FTO mediates tumor growth and resistance to erlotinib in 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 3290.

Abstract 1962: PH009-1, a highly potent, selective and brain-penetrable fourth-generation EGFR-TKI that overcome classic and resistant EGFR mutations in NSCLC

Abstract Background: Epidermal growth factor receptor (EGFR) inhibitors, especially 3rd Gen inhibitor such as osimertinib (Osi), have become the first line therapy for non-small cell lung cancer (NSCLC) patients with EGFR activating mutations. However, treatments with 3rd Gen EGFR inhibitors lead to occurrence of acquired C797S mutation in 10-24% of patients. Though studies showed that double mutations 19Del/C797S (DC) and L858R/C797S (LC) could be inhibited by 1st Gen EGFR TKIs, appearance of triple mutations 19Del/T790M/C797S (DTC) and L858R/T790M/C797S (LTC) always leads to treatment failure. In recent years, 4th Gen EGFR inhibitors have been developed such as BLU-945 and PH009-1. PH009-1 had been reported on AACR annual meeting 2023. Methods: Cell activity and selectivity were determined in engineered Ba/F3 cell lines carrying EGFR wild type (WT, stimulated with EGF), 19Del (D), L858R (L), 19Del/T790M (DT), L858R/T790M (LT), DC, LC, DTC and LTC. The in vivo anti-tumor efficacy and PK-PD studies were performed in cell or patient derived xenograft (CDX or PDX) cancer models (HCC827, D; Ba/F3, LC; PDX, DTC). Brain penetration capability was tested in mice orally treated with PH009-1 for 7 days. Systemic safety of PH009-1 was evaluated in 28-day repeated dosing toxicity studies in rats and dogs following GLP guidelines. Results: PH009-1 displayed potent anti-proliferation activity against Ba/F3 cells harboring EGFR mutations (L, D, LC, DC, LT, DT, LTC, DTC) with IC50 of 2.4, 1.3, 5.2, 1.2, 1.1, 1.5, 2.8, 1.9 nM, respectively, but had very weak effect on EGFR WT Ba/F3 cells (IC50, 1135 nM), suggesting excellent potency and selectivity. In contrast, though BLU-945 potently inhibited DT, LT, DTC, LTC with IC50 less than 5 nM, but its activities on L, D, LC, DC were not strong with IC50 of 31.6, 81.2, 46.2, and 52.0 nM. In in vivo efficacy studies, PH009-1 at a dose of 20 mg/kg BID led to potent inhibition on tumor growth and EGFR phosphorylation, and tumor regression was observed at higher doses in all tested models. In HCC827 model with 19Del (first line therapy setting), mice were treated for more than 200 days, and one tumor relapsed in BLU-945 group but not in PH009-1 or Osi group. Also, deaths were observed in Osi group, but not with PH009-1. After treated mice with PH009-1 at efficacious dose for 7 days, concentrations in cerebrospinal fluids (CSF) at 0-8 h post final dose were more than enough (≥1.5 fold) to cover IC80 on all tested mutations. In GLP toxicity studies, no unexpected toxicity was observed. In dogs. the highest tested dose was determined as highest non-severely toxic dose (HNSTD) and based on high plasma exposure, wide safety margin was confirmed with PH009-1. Conclusion: Our data suggested that PH009-1 overcome T790M/C797S resistant mutations, and also have potential to become a potent and safe approach for first line therapy of NSCLC with EGFR mutations. Citation Format: Feng Gao, Jing Wang, Bin Liu, Yongyong Wu, Liandong Jing, Pengzhi Zhang, Yu Gao, Zhizhong Li, Yongqi Guo. PH009-1, a highly potent, selective and brain-penetrable fourth-generation EGFR-TKI that overcome classic and resistant EGFR mutations in 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 1962.

Genomic heterogeneity at baseline is associated with T790M resistance mutations in EGFR-mutated lung cancer treated with the first-/second-generation tyrosine kinase inhibitors.

This study analyzed whether extended molecular profiling can predict the development of epidermal growth factor receptor (EGFR) gene T790M mutation, which is the most frequent resistance alteration in non-small cell lung cancer (NSCLC) after treatment with the first-/second-generation (1G/2G) EGFR inhibitors (tyrosine kinase inhibitors [TKIs]), but only weakly associated with clinical characteristics. Whole exome sequencing (WES) was performed on pretreatment tumor tissue with matched normal samples from NSCLC patients with (n = 25, detected in tissue or blood rebiopsies) or without (n = 14, negative tissue rebiopsies only) subsequent EGFR p.T790M mutation after treatment with 1G/2G EGFR TKI. Several complex genetic biomarkers were assessed using bioinformatic methods. After treatment with first-line afatinib (44%) or erlotinib/gefitinib (56%), median progression-free survival and overall survival were 12.1 and 33.7 months, respectively. Clinical and tumor genetic characteristics, including age (median, 66 years), sex (74% female), smoking (69% never/light smokers), EGFR mutation type (72% exon 19 deletions), and TP53 mutations (41%) were not significantly associated with T790M mutation (p > 0.05). By contrast, complex biomarkers including tumor mutational burden, the clock-like mutation signature SBS1 + 5, tumor ploidy, and markers of subclonality including mutant-allele tumor heterogeneity, subclonal copy number changes, and median tumor-adjusted variant allele frequency were significantly higher at baseline in tumors with subsequent T790M mutation (all p < 0.05). Each marker alone could predict subsequent development of T790M with an area under the curve (AUC) of 0.72-0.77, but the small number of cases did not allow confirmation of better performance for biomarker combinations in leave-one-out cross-validated logistic regression (AUC 0.69, 95% confidence interval: 0.50-0.87). Extended molecular profiling with WES at initial diagnosis reveals several complex biomarkers associated with subsequent development of T790M resistance mutation in NSCLC patients receiving first-/second-generation TKIs as the first-line therapy. Larger prospective studies will be necessary to define a forecasting model.

A narrative review of antibody-drug conjugates in EGFR-mutated non-small cell lung cancer.

In the past 15 years, non-small cell lung cancer (NSCLC) treatment has changed with the discovery of mutations and the development of new targeted therapies and immune checkpoint inhibitors. Epidermal growth factor receptor (EGFR) was the first mutation in NSCLC to have a drug that was FDA-approved in 2013. Osimertinib, a third-generation tyrosine kinase inhibitor, is approved as first-line therapy for advanced NSCLC and in the adjuvant setting for Stage IB-IIIA resected NSCLC. However, resistance to osimertinib is inevitably an issue, and thus patterns of resistance to EGFR-mutated NSCLC have been studied, including MET amplification, EGFR C797X-acquired mutation, human epidermal growth factor 2 (HER2) amplification, and transformation to small cell and squamous cell lung cancer. Current management for EGFR-mutated NSCLC upon progression of EGFR TKI is limited at this time to chemotherapy and radiation therapy, sometimes in combination with the continuation of osimertinib. Antibody-drug conjugates (ADCs) are made up of a monoclonal antibody linked to a cytotoxic drug and are an increasingly popular class of drug being studied in NSCLC. Trastuzumab deruxtecan has received accelerated FDA approval in HER2-mutated NSCLC. ADCs offer a possible solution to finding a new treatment that could bypass the intracellular resistance mechanism. In this review article, we summarize the mechanism of ADCs and investigational ADCs for EGFR-mutated NSCLC, which include targets to MET amplification, HER3, Trop2, and EGFR, along with other ADC targets being investigated in NSCLC, and discuss future directions that may arise with ADCs in EGFR-mutated NSCLC.

Treatment Patterns and Adverse Event-Related Hospitalization Among Patients with Epidermal Growth Factor Receptor (EGFR)-Mutated Metastatic Non-small Cell Lung Cancer After Treatment with EGFR Tyrosine Kinase Inhibitor and Platinum-Based Chemotherapy Regimens.

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR TKIs) are established first-line treatments among patients with metastatic non-small cell lung cancer harboring EGFR-sensitizing mutations. Upon EGFR TKI resistance, there are scant data supporting a standard of care in subsequent lines of therapy. We aimed to characterize real-world treatment patterns and adverse events associated with hospitalization in later lines of therapy. This retrospective analysis of administrative claims included adults with metastatic non-small cell lung cancer who initiated a next line of therapy (index line of therapy) following EGFR TKI and platinum-based chemotherapy discontinuation on/after 1 November, 2015. Treatment regimens and adverse event rates during the index line of therapy were described. Among 195 eligible patients (median age: 59 years; female: 60%), the five most common index line of therapy regimens were immune checkpoint inhibitor monotherapy (29%), EGFR TKI monotherapy (21%), platinum-based chemotherapy (19%), non-platinum-chemotherapy (13%), and EGFR TKI combinations (9%). The overall median (95% confidence interval) time to discontinuation of the index line of therapy was 2.8 (2.1-3.2) months. Common adverse events associated with hospitalizations included infection/sepsis, pneumonia/pneumonitis, and anemia (2.9, 2.8, and 2.0 per 100 person-months, respectively). Among EGFR TKI-resistant patients who discontinued platinum-based chemotherapy, the duration of the next line of therapy was short, treatment was highly variable, and re-treatment with EGFR TKIs and platinum-based regimens was common, suggesting a lack of standard of care in later lines. Adverse event rates associated with hospitalization were high, especially among platinum-treated patients. These results underscore the unmet need for new therapies in a later line of treatment to reduce the clinical burden among patients in this population.

Epidermal growth factor receptor PROTACs as an effective strategy for cancer therapy: A review.

Epidermal growth factor receptor (EGFR), a transmembrane glycoprotein that mediates cellular signaling pathways involved in cell proliferation, angiogenesis, apoptosis, and metastatic spread, is an important oncogenic drug target. Targeting the intracellular and extracellular domains of the EGFR has been authorized for a number of small-molecule TKIs and mAbs, respectively. However, their clinical application is limited by EGFR catalytic structural domain alterations, cancer heterogeneity, and persistent drug resistance. To bypass these limitations, protease-targeted chimeras (PROTACs) are emerging as an emerging and promising anti-EGFR therapy. PROTACs compensate for the limitations of traditional occupancy-driven small molecules by exploiting intracellular protein destruction processes. Recently, a mushrooming number of heterobifunctional EGFR PROTACs have been created using wild-type (WT) and mutated EGFR TKIs. PROTACs outperformed EGFR TKIs in terms of cellular inhibition, potency, toxicity profiles, and anti-drug resistance. Herein, we present a comprehensive overview of the development of PROTACs targeting EGFR for cancer therapy, while also highlighting the challenges and opportunities associated with the field.

A multicenter study of central nervous system (CNS) metastasis in EGFR-mutated advanced non–small-cell lung cancer in Thailand: CNS progression-free survival analysis.

e14002 Background: Central Nervous System (CNS) metastasis is common in patients with advanced stage non-small cell lung cancer (NSCLC), which impacts their survival and quality of life. Nearly Half of NSCLCs in Thailand are EGFR (Epidermal Growth Factor Receptor) mutated NSCLCs. The aim of this study was to define the prevalence of CNS metastasis in EGFR mutated advanced NSCLC in Thai patients and their survival during the year 2013-2019.Now we reported CNS progression free survival data in subgroup with evidence of CNS progression. Methods: We retrospectively conducted a multicenter study of EGFR mutated advanced NSCLC from 9 government hospitals in Thailand from January 2013 to December2019. Demographic data and cancer treatments were recorded with previous reports of overall survival data in all cohorts. Brain imaging was performed upon neurologic signs and symptoms. Treatment of CNS metastasis, CNS progression date and overall survival data were collected. The analysis of CNS progression free survival and overall survival was performed and the effect of Osimertinib was defined. Results: There were 254 patients with advanced EGFR mutated NSCLCs. The prevalence of CNS metastasis was 32.28% (82 patients). There were 25.6% (21) of patients with definite evidence of CNS progression by imaging or clinical. In this group, Brain metastasis at first diagnosis was 61.9% (13 patients). EGFR TKIs was given as first line 42.9% (9 patients), second line 33.3% (7 patients), third line 19% (4 patients). Whereas one patient did not received EGFR TKIs. Most of EGFR TKIs treatment was first generation for 95% (19 patients). Osimertinib was given in 23.8% (5) of patients as second line, third line and fourth line for 2, 1 and 2 patients, respectively. The onset of CNS metastasis before EGFR TKIs was 76.2% when compared to 4.8%, 19% during EGFR TKIs and after EGFR TKIs, respectively. Treatment of brain metastasis was whole brain radiation for 85.7% (18 patients), followed by surgery with whole brain radiation for 14.3% (3 patients). The median CNS progression free survival was 14.00 (9.51,18.48) months. The median CNS progression free survival between no Osimertinib treatment and Osimertinib treatment was 13 (10.38,15.61) months and 21 (17.49,24.5) months, respectively. The median survival was 30.03 (19.6,40.45) months. The median survival between no Osimertinib treatment and Osimertinib treatment was 26.58 (18.96,34.20) months and NR (NR, NR), respectively. Conclusions: The prevalence of CNS progression was 25.6% in patients with EGFR mutated NSCLC in Thailand. Treatment with EGFR TKIs improved CNS progression free survival better than historical data.3rd generation EGFR TKIs Osimertinib in later line prolong clinical benefit of CNS Progression free survival and overall survival better than 1st generation EGFR TKIs alone.

Safety and preliminary efficacy of YK-029A, a novel EGFR TKI, in patients with advanced NSCLC harboring ex20ins, T790M or rare mutations.

9014 Background: This study aimed to evaluate the safety and preliminary efficacy of YK-029A, a novel third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, in treated or untreated patients with advanced NSCLC. Methods: This dose-escalation and dose-expansion phase 1 trial recruited previously untreated or treated patients with EGFR ex20ins mutant locally advanced or metastatic NSCLC and previously treated patients with EGFR T790M or rare mutations. In dose-escalation phase, patients with EGFR T790M mutation were enrolled. YK-029A was given at doses of 50, 100, 150, 200 to 250 mg/day (3+3 design). In dose-expansion phase, patients with EGFR T790M, EGFR ex20ins, or rare mutations were enrolled. The primary objective was safety. Dose-limiting toxicity (DLT) and maximum tolerated dose (MTD) were explored. In the treatment-naïve cohort of EGFR ex20ins mutant NSCLC, patients were administered oral YK-029A 200 mg once daily in a 28-day cycle, and efficacy was assessed by the independent review committee. The study was registered (chinadrugtrials.org.cn,CTR20180350). Results: A total of 108 were included in the safety analysis set. DLT did not occur in dose-escalation phase. MTD was not reached. Treatment-emergent adverse events (TEAEs) of any grade and grade≥3 occurred in 106 (98.1%) and 41 (38.0%) patients, respectively. Treatment-related adverse events (TRAEs) of any grade and grade≥3 occurred in 102 (94.4%) and 30 (27.8%) patients, respectively. One patient had liver abscess related to YK-029A and died. Three patients terminated the treatment because of TEAEs. The most common TRAEs were diarrhea (46.3%), anemia (38.0%), and rash (32.4%). For the treatment-naïve EGFR ex20ins mutant cohort, 26 patients were included in the efficacy analysis set. Most patients were adenocarcinoma (96.4%) and at stage IV (85.7%). At the cut-off date on October 30, 2022, 19 patients (73.1%) had partial remission, five patients (19.2%) had stable disease, and two patients (7.7%) developed disease progression. The confirmed objective response rate achieved 73.1% (95% confidence interval [CI], 52.21% to 88.43%). The median progression-free survival was 9.3 months (95% CI, 5.85 to not evaluated). Conclusions: YK-029A was well tolerated and showed preliminary efficacy in treatment-naïve EGFR ex20ins mutant patients with locally advanced or metastatic NSCLC. [Table: see text]

Structural elements that enable specificity for mutant EGFR kinase domains with next-generation small-molecule inhibitors.

Specificity for a desired enzyme target is an essential property of small-molecule inhibitors. Molecules targeting oncogenic driver mutations in the epidermal growth factor receptor (EGFR) kinase domain have had a considerable clinical impact due to their selective binding to cancer-causing mutants compared to wild type. Despite the availability of clinically approved drugs for cancers driven by EGFR mutants, persistent challenges in drug resistance in the past decades have led to newer generations of drugs with divergent chemical structures. The current clinical challenges are mainly due to acquired resistance to third-generation inhibitors, including by the acquisition of the C797S mutation. Several diverse fourth-generation candidates and tool compounds that inhibit the C797S mutant have emerged, and their structural characterization has revealed molecular factors that allow for EGFR mutant selective binding. Here, we have reviewed all known structurally-characterized EGFR TKIs targeting clinically-relevant mutations to identify specific features that enable C797S inhibition. Newer generation EGFR inhibitors exhibit consistent and previously underutilized hydrogen bonding interactions with the conserved K745 and D855 residue side chains. We also consider binding modes and hydrogen bonding interactions of inhibitors targeting the classical ATP and the more unique allosteric sites.

Different Tyrosine Kinase Inhibitors Used in Treating EGFR-Mutant Pulmonary Adenocarcinoma with Brain Metastasis and Intracranial Intervention Have No Impact on Clinical Outcomes

Brain metastasis in patients with non-small-cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations is a factor of poor prognosis. We conducted a retrospective study to determine the optimal treatment strategy for EGFR-mutant NSCLC patients with brain metastasis receiving or not receiving intracranial intervention. A total of 186 patients treated with an EGFR TKI were enrolled in the study, and 79 (42%) received intracranial intervention. Patients who received intracranial intervention and those who did not had a similar treatment response rate (RR), progression-free survival (PFS) (median PFS: 11.0 vs. 10.0 months, p = 0.4842), and overall survival (OS) (median OS: 23.0 vs. 23.2 months, p = 0.2484). Patients treated with gefitinib, erlotinib, afatinib, or osimertinib had a similar RR (63%, 76%, 81%, or 100%, respectively, p = 0.1390), but they had significantly different PFS (median PFS: 7.5, 10.0, 14.8 months, or not reached, respectively, p = 0.0081). In addition, OS tended to be different between different EGFR TKI treatments (median OS of 19.2, 23.7, or 33.0 months for gefitinib, erlotinib, or afatinib treatments, respectively, p = 0.0834). Afatinib and osimertinib both demonstrated significantly longer PFS than gefitinib in a Cox regression model. Graded prognostic assessment (GPA) versions 2017 and 2022 stratified patients with different OS; patients with higher GPA index scores had significantly longer OS (p = 0.0368 and 0.0407 for version 2017 and 2022, respectively).

1001P Epidermal growth factor receptor (EGFR) testing and treatment patterns associated with diagnosis of non-small cell lung cancer (NSCLC) with EGFR exon 20 insertions (ex20ins) in the US

With new targeted therapies approved for patients with NSCLC with EGFRex20ins, it is important to understand real-world diagnosis and treatment choice, as these mutations are associated with poor prognosis and require tailored treatment. The Flatiron Health electronic health record database was used to identify 75,067 patients with advanced NSCLC from 01/01/2011 to 12/31/2021. EGFR testing rates and proportion of tests done with next-generation sequencing (NGS) were described for all patients. First-line (1L) treatments were described for patients with EGFRex20ins(+) results in the last 5 years (2017-2021), stratified by initiation of 1L before or after EGFRex20ins(+) testing result. Overall, 67% of patients were tested for EGFR mutations (n=51,470). EGFR testing rates and the proportion of tests done with NGS increased from 2011 to 2021 (44.4 to 80.7% and <1.0 to 81.0%, respectively). Among patients with EGFRex20ins(+) results 2011-2017 (n = 250), 59 (24%) started 1L treatment prior to and 141 (56%) started 1L after their first EGFRex20ins(+) (50 were unknown). A higher proportion of patients received EGFR TKIs or were enrolled in clinical trials, and a lower proportion received chemotherapy if they started 1L treatment after their first EGFRex20ins(+) result, when compared to patients who started 1L treatment before. Similar proportions of patients were treated with IO monotherapy or IO + chemotherapy regardless of when treatment was started (table).Table: 1001P1L treatments in patients with EFRex20ins 2017-2021Started treatment before EGFRex20ins (+) result n (%)Started treatment after EGFRex20ins (+) result n (%)n = 59n = 141Chemotherapy27 (45.8)36 (25.5)IO monotherapy5 (8.5)16 (11.3)IO + chemotherapy21 (35.6)44 (31.2)EGFR TKI4 (6.8)32 (22.7)Clinical Trial1 (1.7)12 (8.5)Other1 (1.7)1 (0.7) Open table in a new tab EGFR testing increased over time; however, 20% of patients still remained untested in 2021. Among patients with EGFRex20ins mutations, a high proportion of patients started IO or EGFR TKIs after genetic testing despite limited effectiveness in this population. With the recent approval of therapies targeting EGFRex20ins mutations, increased testing and awareness of treatment outcomes in this population are needed.

EP08.02-051 High-dose Aumolertinib as First-line Treatment in Patients With Brain Metastases Associated With EGFR Mutated NSCLC

Brain metastases are associated with significant morbidity and poor survival outcomes. They are found in 10-20% of patients with non-small cell lung cancer (NSCLC) at presentation, and in up to 50% of patients during the course of their illness. Brain metastases occur most frequently in patients with adenocarcinoma and tumor harbouring epidermal growth factor receptor (EGFR) mutations or ALK rearrangements, especially after treating with 1st or 2nd generation EGFR TKI. Aumolertinib, the third generation irreversible EGFR TKI, has been developed to target T790M mutation.

A rare case of Exon 19 deletion transforming to Exon 20 insertion in a case of adenocarcinoma of lung

Epidermal growth factor receptor (EGFR) gene mutations play an important role in the presentation, prognosis, and management of non-small cell lung cancer (NSCLC) patients. Several clinical studies claimed the incidence of EGFR Exon 20 insertion mutations in NSCLC and have similar clinical characteristics to those with common EGFR mutations but poorer prognosis. Insertion mutations within the Exon 20 of the EGFR gene are typically located after the C-helix of the tyrosine kinase to result in the domain of EGFR and have been reported to increase the kinase activity of the protein. This eventually leads to the ligand-independent activation of several downstream pathways such as mitogen activated protein kinase (MAPK) and phosphatidylinositol-3-kinase (Pi3K)-(mTOR) mammalian target of rapamycin pathways, which are involved in several cellular processes such as cell proliferation, metastasis, and migration while preventing apoptosis. Thus, EGFR exon insertion mutations are gain of function mutations. Specific EGFR and frame-in insertions occur in 3–7% of NSCLC and are known to predict primary resistance to treatment with all clinically available EGFR-tyrosine kinase inhibitors (TKIs). Many clinical and preclinical studies have reported significant antitumor activity with various first and second-generation EGFR TKIs such as Erlotinib, Gefitinib, and Afatinib and have led to prolonged survival in EGFR mutated patients, as compared to wild-type EGFR tumors with chemotherapy. In addition, third-generation EGFR TKIs, such as Osimertinib, have shown encouraging results in metastatic NSCLC patients harboring EGFR mutations including EGFR, p. Thr790Met-mutations, that have shown to confer resistance to first and second-generation EGFR TKIs and who have progressed on prior TKI therapy. Drugs such as Afatinib, Dacomitinib, Erlotinib, Gefitinib, and Osimertinib have already gained FDA approval for use in EGFR-mutated metastatic NSCLC patients. Here, we report the case of a 47-year-old man who is a non-smoker with an EGFR Exon 19 positive NSCLC treated with Gefitinib developed an EGFR Exon 20 insertion positive brain metastasis initiated on Afatinib as the targeted therapy and responded well to the treatment.

Mebendazole Loaded Nanoparticles for Lung Cancer Therapy

Lung cancer is the leading cause of cancer mortality. Lung cancers are classified into two types based on their microscopic appearance: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Many individuals are first diagnosed at stage III or IV, when their prognosis is bleak. Non-small cell lung cancer is a lethal and incurable illness that can be treated with surgery, chemotherapy, radiation therapy, targeted therapy, or a combination of therapies. Targeted treatment focuses on particular abnormalities seen in cancer cells, such as the Epidermal growth factor receptor (EGFR) mutation. The T 790M mutation in the EGFR’s tyrosine kinase domain causes acquired resistance to first-generation EGFR TKIs, mebendazole. As a result, combining diverse targeted therapeutic drugs not only improves treatment outcomes but can also be a more effective preventer of acquired resistance improvement. Loaded drug Nanoparticles ZSM-5 and SBA-16 were utilized as targeted treatment, and their stability and loading % were determined using multiple methods, including infrared, X-Ray Diffraction, TGA, and HPLC. The therapy was used in in-vitro cell culture investigations such as the MMT assay, colony assay, and migration assay. The results showed that the loaded drug nanoparticles had a lower IC50 than the free drug mebendazole we utilized, indicating that the nanoparticles improved therapy and reduced medication dosage.

The benefits of G8 and VES-13 geriatric screening tools for older patients with advanced lung cancer

Cancer is a disease of ageing. There is scarce evidence to guide proper cancer treatment decisions for this population because older patients, especially those with age-related comorbidities, are under-represented in clinical trials [1]. During the past decades, there have been major breakthroughs in non-small cell lung cancer treatment. Up to half of the Asian patients with adenocarcinoma harbor epidermal growth factor receptor (EGFR) mutations – the predictive biomarker of EGFR tyrosine kinase inhibitors (EGFR TKIs) [2].

Switch to EGFR-TKI after upfront platinum doublet induction therapy in non-small cell lung cancer (NSCLC) patients with EGFR (Epidermal Growth Factor Receptor) mutation: A multicentre retrospective study

Introduction of EGFR-TKI has changed the treatment paradigm for NSCLC patient with activating mutations of EGFR exons 18–21, replacing chemotherapy as standard first line treatment. Given the delays in molecular study results we sometimes face the need to start treatment in very symptomatic patients with high tumor burden. The reason for this retrospective study is to analyze the survival impact of performing an induction cytotoxic therapy until obtaining the molecular profile (EGFR mutation), followed by targeted therapy.This is a retrospective analysis of 31 patients who did upfront chemotherapy (ChT) before switching to EGFR TKI upon the molecular profile result. The calculated survival endpoints were progression-free survival (PFS), duration of TKI response and overall survival (OS).All patients were treated with upfront chemotherapy with a median of one cycle (range 1–3) followed by a first generation EGFR-TKI. Median PFS was 13 months (95% CI, 6.6–19.4) and median OS 33 months (95% CI, 11.9–54.0). After first line progression 14 patients were treated with Osimertinib. In this subgroup median OS was 52 months (95% CI, 34.0–69.9). In the multivariable Cox model, only body mass index retained independent prognostic significance for progression-free survival (p = 0.045).Survival outcomes in this cohort are in line with published data regarding first generation EGFR-TKI, both in terms of PFS and OS. Despite the limitations of this study, starting with upfront chemotherapy doesn't seem detrimental in terms of survival outcomes, with the potential advantage of symptomatic control. To our knowledge, this is the first study to address this strategy, which requires further confirmation.

EGFR-D770>GY and Other Rare EGFR Exon 20 Insertion Mutations with a G770 Equivalence Are Sensitive to Dacomitinib or Afatinib and Responsive to EGFR Exon 20 Insertion Mutant-Active Inhibitors in Preclinical Models and Clinical Scenarios.

Epidermal growth factor receptor (EGFR) exon 20 insertion mutations account for a tenth of all EGFR mutations in lung cancers. An important unmet clinical need is the identification of EGFR exon 20 insertion mutants that can respond to multiple classes of approved EGFR-TKIs. We sought to characterize variants involving EGFR-D770 to EGFR-G770 position equivalence changes that structurally allow for response to irreversible 2nd generation EGFR-TKIs. Our group used preclinical models of EGFR exon 20 insertion mutations to probe representative 1st (erlotinib), 2nd (afatinib, dacomitinib), 3rd generation (osimertinib) and EGFR exon 20 insertion mutant-active (poziotinib, mobocertinib) TKIs; we also queried the available clinical literature plus our institutional database to enumerate clinical outcomes. EGFR-D770>GY and other EGFR insertions with a G770 equivalence were identified at a frequency of 3.96% in separate cohorts of EGFR exon 20 insertion mutated lung cancer (n = 429). Cells driven by EGFR-D770>GY were insensitive to erlotinib and osimertinib, displayed sensitivity to poziotinib and dacomitinib and were uniquely sensitive to afatinib and dacomitinib in comparison with other more typical EGFR exon 20 insertion mutations using proliferation and biochemical assays. Clinical cases with EGFR-G770 equivalence from the literature and our center mirrored the preclinical data, with radiographic responses and clinical benefits restricted to afatinib, dacomitinib, poziotinib and mobocertinib, but not to erlotinib or osimertinib. Although they are rare, at <4% of all exon 20 insertion mutations, EGFR-G770 equivalence exon 20 insertion mutations are sensitive to approved 2nd generation EGFR TKIs and EGFR exon 20 insertion mutant-active TKIs (mobocertinib and poziotinib). EGFR-D770>GY and other insertions with a G770 equivalence join EGFR-A763_Y764insFQEA as exon 20 insertion mutationsresponsive to approved EGFR TKIs beyond mobocertinib; this data should be considered for clinical care, genomic profiling reports and clinical trial elaboration.

RESTRICTING EXTRACELLULAR CA2+ ON GEFITINIB RESISTANT NON-SMALL CELL LUNG CANCER CELLS REVERSES ALTERED EPIDERMAL GROWTH FACTOR MEDIATED CA2+ RESPONSE, WHICH CONSEQUENTLY ENHANCES GEFITINIB SENSITIVITY

TOPIC: Lung Cancer TYPE: Original Investigations PURPOSE: Non-small cell lung cancer (NSCLC), one of the leading causes of cancer-related death, has a low 5-year survival rate owing to the inevitable acquired resistance toward antitumor drugs, platinum-based chemotherapy, and targeted therapy. Epidermal growth factor (EGF)-EGF receptor (EGFR) signaling activates downstream events leading to phospholipase C/inositol trisphosphate (IP3)/Ca2+ release from IP3-sensitive Ca2+ stores to modulate cell proliferation, motility, and invasion. However, the role of EGFR-mediated Ca2+ signaling in acquired drug resistance is not fully understood. METHODS: We analyzed the intracellular calcium ([Ca2+]i) signals in PC-9 cells and PC-9/GR (Gefitinib Resistant) cells under following conditions. We observed hEGF (200ng/ml)-mediated [Ca2+]i oscillations response. Calcium influx, endoplasmic reticulum (ER) calcium contents, hEGF (200 ng/ml)-mediated [Ca2+]i oscillations, and effects of inhibitors were studied in absence of extracellular calcium ([Ca2+]e). We compared gefitinib-induced cytotoxicity and cell viability according to the presence or absence of [Ca2+]e. RESULTS: NSCLC PC-9 cells and gefitinib resistant NSCLC PC-9/GR cells, and we found that acute EGF treatment elicited intracellular Ca2+ ([Ca2+]i) oscillations in PC-9 cells but not in PC-9/GR cells. PC-9/GR cells presented a more sustained basal [Ca2+]i level, lower endoplasmic reticulum Ca2+ level, and higher spontaneous extracellular Ca2+ ([Ca2+]e) influx than PC-9 cells. Notably, restricting [Ca2+]e in both cell types induced identical [Ca2+]i oscillations, dependent on phospholipase C and EGFR activation. Consequently, restricting [Ca2+]e in PC-9/GR cells upregulated gefitinib-mediated poly (ADP-ribose) polymerase cleavage, an increase in Bax/Bcl-2 ratio, cytotoxicity, and apoptosis. In addition, nuclear factor of activated T cell (NFAT1) induction in response to EGF was inhibited by gefitinib in PC-9 cells, whereas EGF-mediated NFAT1 induction in PC-9/GR cells was sustained regardless of gefitinib treatment. Restricting [Ca2+]e in PC-9/GR cells significantly reduced EGF-mediated NFAT1 induction. CONCLUSIONS: These findings indicate that spontaneous [Ca2+]e influx in NSCLC cells plays a pivotal role in developing acquired drug resistance and suggest that restricting [Ca2+]e may be a potential strategy for modulating drug-sensitivity. CLINICAL IMPLICATIONS: resistant mechanism in EGFR TKI DISCLOSURES: no disclosure on file for Misung Kim; no disclosure on file for Sohui Kim; no disclosure on file for Minsuk Kim; No relevant relationships by Seihoon Yang, source=Web Response

P50.05 Natural History and Real-World Treatment Outcomes for NSCLC Patients with EGFR Exon 20 Insertion Mutation: An IASLC- ASCO CancerLinQ Study

Epidermal Growth Factor Receptor (EGFR) exon 20 insertion (ex20ins) mutations account for 2-3% all non-small cell lung cancer (NSCLC) patients. Patients with ex20 ins do not respond to standard EGFR TKI therapy. In this work, we have analyzed the characteristics, treatment patterns and outcomes in this subgroup of NSCLC patients. The ASCO CancerLinQ Discovery dataset was queried to identify patients diagnosed with NSCLC between the years 1995-2018 and with EGFR ex20ins mutations. Data were extracted on patient demographics, tumor characteristics, treatments and outcomes, and compared with Chi-square and ANOVA tests. Kaplan-Meier (KM) curves were generated for comparing overall survival with log-rank tests. All analyses were performed using Python 3.6. A total of 357 patients were eligible. Patient characteristics: median age 68 years, female 53.5%, white race 63% and black race 9%. Approximately 62% had stage 4 disease, and 30% had brain metastasis. 54% of the patients were treated with chemotherapy and 15% with immune check point inhibitors (ICI). In patients with brain metastasis, 16% were treated with ICI, 18% targeted therapy and 59% with chemotherapy. The median survival of the entire group is 23.8 months. Among patients with stage 4 disease: 51% were females, 64% white race, 37% had brain metastasis, 18% were treated with ICI, 14% targeted therapy and 60% treated with chemotherapy. In the analysis of stage 4 patients, the median survival of the group was 16.8 months. Stage 4 patients that received ICI had better survival vs. those who did not (29.1 vs. 14.7 months; p=0.01). Stage 4 patients treated with ICI and chemotherapy had better survival compared to those treated with chemotherapy alone (29.1 vs. 16.5 months, p=0.01). Stage 4 patients treated with targeted therapy had better survival compared to those that did not receive targeted therapy (20.6 vs. 16.1 months; p=0.03). Stage 4 NSCLC patients with EGFR ex20ins mutation had favorable real-world survival when treated with ICI and targeted therapy.