Epidermal Growth Factor Receptor Resistance Research Articles

EGFR degraders in non-small-cell lung cancer: Breakthrough and unresolved issue.

The epidermal growth factor receptor (EGFR) has been well validated as a therapeutic target for anticancer drug discovery. Osimertinib has become the first globally accessible third-generation EGFR inhibitor, representing one of the most advanced developments in non-small-cell lung cancer (NSCLC) therapy. However, a tertiary Cys797 to Ser797 (C797S) point mutation has hampered osimertinib treatment in patients with advanced EGFR-mutated NSCLC. Several classes of fourth-generation EGFR inhibitors were consequently discovered with the aim of overcoming the EGFRC797S mutation-mediated resistance. However, no clinical efficacy data of the fourth-generation EGFR inhibitors were reported to date, and EGFRC797S mutation-mediated resistance remains an "unmet clinical need." Proteolysis-targeting chimeric molecules (PROTACs) obtained from EGFR-TKIs have been developed to target drug resistance EGFR in NSCLC. Some PROTACs are from nature products. These degraders compared with EGFR inhibitors showed better efficiency in their cellular potency, inhibition, and toxicity profiles. In this review, we first introduce the structural properties of EGFR, the resistance, and mutations of EGFR, and then mainly focus on the recent advances of EGFR-targeting degraders along with its advantages and outstanding challenges.

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

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

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.

Abstract C036: A Phase 1 Study to assess BDTX-1535, an oral EGFR inhibitor, in patients with Glioblastoma or Non-Small Cell Lung Cancer

Abstract Background: Epidermal growth factor receptor (EGFR) is a potent oncogene commonly altered in non-small cell lung cancer (NSCLC) and glioblastoma (rGBM). For NSCLC, EGFR tyrosine kinase activity can be driven by classical driver, intrinsic driver, and acquired resistance mutations. BDTX-1535 is an orally available, highly potent, brain penetrant, selective, irreversible small molecule tyrosine kinase inhibitor that targets all 3 classes of EGFR mutations. Preclinical data demonstrated the ability of BDTX-1535 to cross the blood-brain barrier and produce sustained inhibition of EGFR signaling. Methods: BDTX-1535-101 (NCT05256290) is a Phase 1, open-label, multicenter study to assess the safety, tolerability, pharmacokinetics (PK), central nervous system (CNS) activity, and preliminary antitumor activity of BDTX-1535 in locally advanced or metastatic NSCLC with or without CNS disease or recurrent GBM (rGBM). The primary objective is to determine the BDTX-1535 recommended Phase 2 dose (RP2D) based on the overall safety, PK, pharmacodynamic, and preliminary antitumor activity. The monotherapy dose escalation portion evaluates BDTX-1535 in patients with locally advanced/metastatic NSCLC harboring intrinsic driver EGFR mutations following standard of care or with acquired resistance EGFR mutations following a 3rd generation EGFR inhibitor in the 1st line setting, in addition to patients with rGBM expressing EGFR alterations who previously received available standard therapy of surgical resection followed by chemoradiotherapy and/or temozolomide (TMZ). A capsule-to-tablet bridging cohort and a food effect cohort will also be assessed. Following the establishment of a preliminary recommended Phase 2 dose (RP2D), the disease-specific expansion portion of the study will further evaluate the safety, tolerability, and preliminary antitumor effect of BDTX-1535. Cohorts include the following:1) advanced/metastatic NSCLC with intrinsic resistance EGFR mutations following up to 2 lines of therapy, one of which must be an EGFR inhibitor treatment, 2) advanced/metastatic NSCLC with acquired resistance EGFR mutation following a 3rd generation EGFR inhibitor in the first line setting, 3) rGBM with confirmed EGFR alterations with or without amplifications. NSCLC patients may enroll with or without CNS metastases and must not be known to express excluded resistance mutations such as EGFR T790M. BDTX-1535 will also be studied in combination with TMZ to assess safety, tolerability, and a recommended combination dose for the treatment of patients with newly diagnosed GBM harboring EGFR alterations. Enrollment was initiated in 2022 and dose escalation is almost complete. Initiation of the dose expansion cohorts of NSCLC patients with EGFR acquired resistance and intrinsic driver mutations after progression on prior EGFR inhibitor is planned for the second half of 2023. For additional information, please contact ClinicalTrials@bdtx.com. Citation Format: Helena Yu, Melissa Johnson, Jason T Henry, Alex Spira, Ji-Youn Han, Minal Barve, James Battiste, Iyad Alnahhas, DoHyun Nam, Jeffrey Edenfield, Balazs Halmos, Shinkyo Yoon, Tae Min Kim, Sudharshan Eathiraj, Julio Hajdenberg, Sergey Yurasov, Manmeet Ahluwalia, Patrick Wen. A Phase 1 Study to assess BDTX-1535, an oral EGFR inhibitor, in patients with Glioblastoma or Non-Small Cell Lung Cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C036.

Exploring EGFR inhibitors with the aid of virtual screening, docking, and dynamics simulation studies

In humans, Epidermal Growth Factor Receptor (EGFR) is linked to small-cell lung cancer, breast cancer, and glioblastoma. Receptor kinase inhibitors against EGFR have become a standard treatment option for non-small cell lung cancer (NSCLC), breast cancer patients, and even for those with EGFR mutations or resistance. About 2734 FDA-approved medication compounds were subjected to virtual screening for EGFR kinase inhibitory activity. The top 30 molecules were chosen based on the binding affinity scores and subjected to extra-precision docking and binding free energy analysis. The ADMET profile of the top three hit molecules was verified to confirm their druggability nature. Top three hits- compound 1047 (ZINC000001550477), 1302 (ZINC00003781952), and 2332 (ZINC000019632618) were identified on account of their MMGBSA binding affinity values. The top three hit compounds were subjected to molecular dynamics (MD) simulation for 100 ns. The dynamic nature of the ligand-protein complex was analyzed which corroborated the results of molecular docking and MMGBSA analysis studies. All the top three hits were further subjected to steered MD studies for testing the strength of these ligand-receptor binding in the presence of an external force. Compound 2332 (ZINC000019632618) was identified as the best hit molecule that can be used as a lead to develop newer derivatives of EGFR kinase inhibitors. Communicated by Ramaswamy H. Sarma

A phase 1 study to assess BDTX-1535, an oral EGFR inhibitor, in patients with glioblastoma or non–small-cell lung cancer.

TPS9156 Background: The epidermal growth factor receptor (EGFR) is a potent oncogene commonly altered in many cancers, including glioblastoma (GBM) and non-small cell lung cancer (NSCLC). EGFR tyrosine kinase activity driven by common EGFR mutations can be inhibited by small molecules, however, resistance to available agents may be driven by mutations in the EGFR active kinase site or other regions. BDTX-1535 is an orally available, highly potent, selective, irreversible inhibitor of EGFR mutations, including extracellular variants and amplifications commonly expressed in GBM and inhibits the common and uncommon EGFR mutations found in NSCLC, including the C797S mutation acquired following 3rd generation EGFR inhibitor therapy. Preclinical data demonstrated the ability of BDTX-1535 to cross the blood-brain barrier and produce sustained inhibition of EGFR signaling. Preclinical studies suggest that BDTX-1535 has the potential to be clinically active in suppressing tumor growth in patients with GBM and NSCLC with or without CNS metastases, including a potential survival benefit. Methods: BDTX-1535-101 (NCT05256290) is Phase 1, open-label, multicenter study to assess the safety, tolerability, PK, CNS activity, and preliminary antitumor activity of BDTX-1535 in recurrent GBM (rGBM) or locally advanced or metastatic NSCLC with or without CNS disease. The Monotherapy Dose Escalation portion will evaluate BDTX-1535 in patients with either rGBM expressing EGFR alterations or locally advanced/metastatic NSCLC harboring sensitizing EGFR mutations with or without CNS disease. Patients with rGBM must have previously received available standard therapy of surgical resection followed by chemoradiotherapy and/or temozolomide (TMZ). Eligible NSCLC patients must have EGFR mutated NSCLC that has progressed following standard of care EGFR inhibitor therapy. Once a provisional recommended Phase 2 dose (RP2D) has been established, BDTX-1535 monotherapy will be explored in the following Dose Expansion cohorts to further evaluate safety, PK, and preliminary assessment of efficacy: 1) rGBM with confirmed EGFR alterations, 2) NSCLC with uncommon EGFR mutations following EGFR inhibitor therapy; 3) NSCLC with acquired EGFR resistance mutation following a 3rd generation EGFR inhibitor in 1L setting. NSCLC patients may enroll with or without CNS metastases and must not be known to express excluded resistance mutations such as EGFR T790M or MET. BDTX-1535 will also be studied in combination with TMZ to assess safety, tolerability, and a recommended combination dose for the treatment of patients with rGBM harboring EGFR mutations or variants. Enrollment was initiated in 2022 and dose escalation is ongoing. Dose Expansion cohorts are expected to open in 2023. For additional information, please contact BDTX_1535_101_Study@bdtx.com . Clinical trial information: NCT05256290 .

A real-world study of Afatinib plus ramucirumab in treatment-naïve, EGFR-mutated, non–small cell lung cancer

BackgroundRecent reports suggested combining ramucirumab with epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) to overcome EGFR resistance in non–small cell lung cancer (NSCLC). Nonetheless, evidence supporting the activity of afatinib and ramucirumab is lacking. This study investigated the survival benefits and safety profile of afatinib plus ramucirumab in patients with treatment-naïve, EGFR-mutated, metastatic NSCLC.Materials and methodsThe medical records of patients with EGFR-mutated NSCLC were retrospectively retrieved. Patients who received first-line sequential afatinib followed by ramucirumab and the first-line combination of afatinib plus ramucirumab were included. The Kaplan-Meier was used to estimate the progression-free survival (PFS) of all included patients, patients on sequential afatinib followed by ramucirumab (PFS1), and patients on the up-front combination of afatinib and ramucirumab (PFS2).ResultsThirty-three patients were included (25 women; median age: 63 [45–82] years). The median follow-up of the included patients was 17 months (range 6–89 months). the median PFS for the whole cohort was 71 months (95% CI 67.2–74.8) with eight events during the follow-up. The median PFS1 and PFS2 were 71 months (95 CI not defined) and 26 months (95% CI 18.6–33.4), respectively. In terms of OS, the median OS for all patients and patients on sequential treatment was not defined, while the median OS for patients on upfront combination was 30 months (95% CI 20.9–39.1). There was no significant association between EGFR mutation type and PFS1 or PFS2.ConclusionsAfatinib plus ramucirumab could improve the PFS of patients with EGFR-positive NSCLC at a predictable safety profile. Our data also suggest a survival benefit of adding ramucirumab to afatinib in patients with uncommon mutations, which should be investigated further.

Abstract CT127: A phase 1 study to assess BDTX-1535, an oral EGFR inhibitor, in patients with glioblastoma or non-small cell lung cancer

Abstract Background: The epidermal growth factor receptor (EGFR) is a potent oncogene commonly altered in many cancers, including glioblastoma (GBM) and non-small cell lung cancer (NSCLC). EGFR tyrosine kinase activity driven by common EGFR mutations can be inhibited by small molecules, however, resistance to available agents may be driven by mutations in the EGFR active kinase site or other regions. BDTX-1535 is an orally available, highly potent, selective, irreversible inhibitor of EGFR mutations, including extracellular variants and amplifications commonly expressed in GBM and inhibits the uncommon EGFR mutations found in NSCLC, including the C797S mutation acquired following 3rd generation EGFR inhibitor therapy. Preclinical data demonstrated the ability of BDTX-1535 to cross the blood-brain barrier and produce sustained inhibition of EGFR signaling. Preclinical studies suggest that BDTX-1535 has potential to be clinically active in suppressing tumor growth in patients with GBM and NSCLC with or without CNS metastases, including a potential survival benefit. Methods: BDTX-1535-101 (NCT05256290) is Phase 1, open-label, multicenter study to assess the safety, tolerability, PK, CNS penetrance, and preliminary antitumor activity of BDTX-1535 in recurrent GBM (rGBM) or locally advanced or metastatic NSCLC with or without CNS disease. The Monotherapy Dose Escalation portion will evaluate BDTX-1535 in patients with either rGBM expressing EGFR alterations or locally advanced/metastatic NSCLC harboring sensitizing EGFR mutations with or without CNS disease. Patients with rGBM must have previously received available standard therapy of surgical resection followed by chemoradiotherapy and/or temozolomide (TMZ). Eligible NSCLC patients must have EGFR mutated NSCLC that has progressed following standard of care EGFR inhibitor therapy. Once a provisional recommended Phase 2 dose (RP2D) has been established, BDTX-1535 monotherapy will be explored in the following Dose Expansion cohorts to further evaluate safety, PK, and preliminary assessment of efficacy: 1) rGBM with confirmed EGFR alterations, 2) NSCLC with uncommon EGFR mutations following EGFR inhibitor therapy; 3) NSCLC with acquired EGFR resistance mutation following a 3rd generation EGFR inhibitor in 1L setting. NSCLC patients may enroll with or without CNS metastases and must not be known to express excluded resistance mutations such as EGFR T790M or MET. BDTX-1535 will also be studied in combination with TMZ to assess safety, tolerability, and a recommended combination dose for the treatment of patients with rGBM harboring EGFR mutations or variants. Enrollment was initiated in 2022 and dose escalation is ongoing. Dose Expansion cohorts are expected to open in 2023. For additional information, please contact BDTX_1535_101_Study@bdtx.com Citation Format: Melissa Johnson, Jason Henry, Alex Spira, James Battiste, Iyad Alnahhas, Manmeet Ahluwalia, Minal Barve, Jeffrey Edenfield, DoHyun Nam, Sudharshan Eathiraj, Julio Hajdenberg, Sergey Yurasov, Helena Yu, Patrick Wen. A phase 1 study to assess BDTX-1535, an oral EGFR inhibitor, in patients with glioblastoma or non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT127.

Design, Synthesis, and Antitumor Activity of Potent and Selective EGFR L858R/T790M Inhibitors and Identification of a Combination Therapy to Overcome Acquired Resistance in Models of Non-small-cell Lung Cancer.

Epidermal growth factor receptor (EGFR) is one of the most studied drug targets for the treatment of non-small-cell lung cancer (NSCLC). Here, we report the identification, structure optimization, and structure-activity relationship studies of quinazoline derivatives as novel selective EGFR L858R/T790M inhibitors. The most promising compound, 28f, exhibited strong inhibitory activity against EGFR L858R/T790M (IC50 = 3.5 nM) and greater than 368-fold selectivity over EGFR WT (IC50 = 1290 nM), a 6.7-fold improvement over osimertinib. Furthermore, 28f effectively inhibited downstream signaling pathways and induced apoptosis in mutant cells. In the H1975 xenograft in vivo model, 28f exhibited a good tumor suppressive effect. Furthermore, the combination of 28f with the ACK1 inhibitor dasatinib produced synergistic antiproliferative efficacy with 28f in 28f-resistant cells and in vivo. In conclusion,28f could become a candidate drug for the treatment of NSCLC, and the combination of 28f and dasatinib is expected to overcome EGFR resistance.

Overcoming EGFR Resistance in Metastatic Colorectal Cancer Using Vitamin C: A Review.

Targeted monoclonal antibody therapy against Epidermal Growth Factor Receptor (EGFR) is a leading treatment modality against metastatic colorectal cancer (mCRC). However, with the emergence of KRAS and BRAF mutations, resistance was inevitable. Cells harboring these mutations overexpress Glucose Transporter 1 (GLUT1) and sodium-dependent vitamin C transporter 2 (SVCT2), which enables intracellular vitamin C transport, leading to reactive oxygen species generation and finally cell death. Therefore, high dose vitamin C is proposed to overcome this resistance. A comprehensive search strategy was adopted using Pubmed and MEDLINE databases (up to 11 August 2022). There are not enough randomized clinical trials to support its use in the clinical management of mCRC, except for a subgroup analysis from a phase III study. High dose vitamin C shows a promising role in overcoming EGFR resistance in mCRC with wild KRAS mutation with resistance to anti-epidermal growth factor inhibitors and in patients with KRAS and BRAF mutations.

Research progress on the mechanism and countermeasures of acquired EGFR resistance

Epidermal growth factor receptor (EGFR) -tyrosine kinase inhibitors (TKI) have transformed traditional cancer treatment and brought good news to patients with non-small cell lung cancer. However, drug resistance problems arise one after another. Based on further exploration of the mechanism of EGFR resistance and corresponding therapeutic strategies, the author reviewed relevant literature, classified and summarized it, providing ideas for solving the clinical problem of EGFR resistance and providing hope for tumor patients.

398TiP MARIPOSA-2: Randomized phase III study of amivantamab + lazertinib + chemotherapy vs chemotherapy alone in EGFR-mutant NSCLC after osimertinib failure

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) effectively treat patients with non-small cell lung cancer (NSCLC) with EGFR-sensitizing mutations; however, almost all will eventually relapse due to new mutations on or after osimertinib the 3rd generation TKI. The current standard of care is platinum doublet chemotherapy after progression on osimertinib, but with limited benefit. Amivantamab, an EGFR and MET bispecific humanized antibody, has shown clinical activity against tumors with primary activating EGFR mutations, EGFR resistance mutations, or MET pathway activation.

Identification of EGFR-Related LINC00460/mir-338-3p/MCM4 Regulatory Axis as Diagnostic and Prognostic Biomarker of Lung Adenocarcinoma Based on Comprehensive Bioinformatics Analysis and Experimental Validation.

Simple SummaryWhile the epidermal growth factor receptor (EGFR) is an important target for lung adenocarcinoma (LUAD) therapy, acquired resistance is still inevitable. A comprehensive bioinformatics analysis strongly suggested that the closely related LINC00460-mir-338-3p-MCM4 ceRNA network of EGFR plays an important role in the diagnosis and prognosis of LUAD. High expression of LINC00460 and MCM4 predicts shorter patient survival. Univariate and multivariate regression analyses demonstrated that higher expression of LINC00460 and MCM4 was significantly associated with tumor size, lymph node metastasis, distant metastasis and TNM stage. A multi-gene regulation model analysis revealed that the LINC00460 (downregulation)—mir-338-3p (upregulation))—MCM4 (downregulation) pattern significantly improved the overall survival of LUAD patients. We also verified the expression of these genes in LUAD cell lines and tumor tissues by RT-PCR and immunohistochemistry. Finally, the possible targeted drugs of MCM4 were queried through the drug database platform, hoping to solve its drug resistance problem by targeting EGFR-related genes.Background: Lung adenocarcinoma (LUAD) is one of the most aggressive and lethal tumor types and requires effective diagnostic and therapeutic targets. Though the epidermal growth factor receptor (EGFR) is an important target for LUAD therapy, acquired resistance is still inevitable. In recent years, the regulation of the EGFR by competing endogenous RNAs (ceRNAs) has been extensively studied and significant progress has been made. Therefore, we aim to find new targets for the diagnosis and treatment of LUAD by analyzing the EGFR-related ceRNA network in LUAD and expect to address the problem of EGFR resistance. Methods: We identified differentially expressed lncRNAs, miRNAs and mRNAs closely associated with the EGFR by analyzing transcriptome data from LUAD samples. Comprehensive bioinformatics analysis strongly suggests that the LINC00460—mir-338-3p—MCM4 ceRNA network plays an important role in the diagnosis and prognosis of LUAD. The effects of different patterns of the LINC00460/MCM4 axis on the overall survival of patients with LUAD were analyzed by a polygene regulation model. We also verified the expression of these genes in LUAD cell lines and tumor tissues by RT-PCR and immunohistochemistry. The functional enrichment analysis and targeted drug prediction of the MCM4 gene were performed. Results: Survival analysis indicated that high expressions of LINC00460 and MCM4 predict a shorter survival period for patients. Univariate and multivariate regression analyses demonstrated that higher expressions of LINC00460 and MCM4 were significantly associated with tumor size, lymph node metastasis, distant metastasis and TNM stage. A multi-gene regulation model analysis revealed that the LINC00460 (downregulation)—mir-338-3p (upregulation)—MCM4 (downregulation) pattern significantly improved the overall survival of LUAD patients (p = 0.0093). RT-PCR and immunohistochemical experiments confirmed our analytical results. In addition, the functional enrichment analysis indicated that MCM4-related genes were mainly enriched in the cell cycle and cell division. A functional association network analysis showed that MCM4 was closely related to the EGFR. Finally, the possible targeted drugs of MCM4 were queried through the drug database platform, hoping to solve its drug resistance problem by targeting EGFR-related genes. Conclusions: In summary, the LINC00460/MCM4 axis can be used as a potential new perspective for targeting EGFR genes in precision medicine and is expected to serve as a diagnostic, prognostic and drug target for LUAD.

New Strategies and Novel Combinations in EGFR TKI-Resistant Non-small Cell Lung Cancer.

Osimertinib is the current standard-of-care for the first-line treatment of Epidermal Growth Factor Receptor (EGFR)-mutant non-small cell lung cancer (NSCLC). Progression after osimertinib ineluctably occurs, and standard of care treatment options beyond progression have mainly included next-line platinum doublet chemotherapy. With better understanding of the varied molecular mechanisms of resistance to osimertinib, several opportunities for the use of targeted agents are emerging that include MET amplification, observed in 15% of patients, and resistant EGFR mutations, including C797S in 7% of patients. Evidence for the use of targeted therapies in such situations is mostly based on case reports, but clinical trials are being conducted with MET inhibitors, such as amivantamab, an EGFR-MET bispecific antibody, or next-generation EGFR inhibitors, such as patritumab-deruxtecan, a HER3 antibody drug conjugate. In this review, we outline our proposed approach to current clinical practice for patients with EGFR mutant, osimertinib-resistant NSCLC which includes the following potential strategies: - Continuation of osimertinib beyond progression following local ablative treatment of oligoprogressive disease, - Tissue rebiopsy of progressive site and possibly concurrent liquid biopsy to evaluate for mechanism of resistance utilizing comprehensive genomic profiling, -Discussion at a molecular tumor board for assessment for enrollment in clinical trials/expanded access program if available with innovative drugs or possible off-label use of available targeted agents, based on the results of molecular profiling, -If no mechanism of resistance identified, administration of platinum-based chemotherapy with antiangiogenic agents. The role of immunotherapy will also be addressed given the uncertain benefit.

64 (PB054) - BDTX-1535, a fourth generation EGFR inhibitor, targeting intrinsic and acquired resistance mutations in NSCLC

Background: The classical mutations of the epidermal growth factor receptor (EGFR) in NSCLC are the exon 19 del and exon 21 (L858R) mutations. The 3rd generation EGFR tyrosine kinase inhibitor (TKI), osimertinib, has become the first-line treatment of choice for NSCLC patients with these mutations. Resistance to 3rd generation TKIs can be driven by gain of secondary EGFR alterations, e.g., substitution at cysteine-797 to serine (C797S). Real world evidence shows that in addition to C797S, other EGFR alterations are also acquired upon osimertinib treatment, including kinase domain mutations (e.g., S768I), extracellular domain alterations (e.g., EGFRvIII, A289X), and EGFR amplification. In addition to the classical mutations, NSCLC tumors express a wide spectrum of primary kinase domain mutations including G719X in exon 18, S768I in exon 20, and L861Q in exon 21, which confer intrinsic resistance to approved TKIs. NCCN guidelines recommend the use of afatinib or osimertinib, however, there remains a need for an EGFR TKI that targets these mutations with high potency, good tolerability, and CNS penetration. Our MAP platform allowed us to select MasterKey inhibitor BDTX-1535, a 4th-generation CNS penetrant EGFR TKI, that potently and selectively targets multiple intrinsic and acquired resistance EGFR alterations. Materials and Methods: BDTX-1535 preclinical exposure was evaluated across species, and PK and Kpuu values were calculated in brain and plasma. Antitumor activity was assessed across a broad range of mouse PDX and allograft models. Results: BDTX-1535 is a potent and selective, CNS penetrant, wild type sparing, irreversible EGFR TKI targeting Exon 18–21 alterations which are associated with intrinsic or acquired resistance to 3rd generation EGFR inhibitors. These include a broad range of kinase domain EGFR mutations (e.g., C797S, L718Q, G724S, S768I), extracellular domain alterations (e.g., EGFRvIII, A289X), and EGFR amplification. Mouse xenograft and allograft studies showed that BDTX-1535 consistently achieves regression of tumors carrying these mutations at well tolerated doses without significant EGFR wild type associated toxicities. BDTX-1535 is orally bioavailable with a CNS Kpuu of 0.55 and 0.48 in rat and dog, respectively, and active in an intracranial PDX model. Conclusions: BDTX-1535 is a 4th generation CNS penetrant EGFR TKI discovered using the MAP platform which allows MasterKey targeting of EGFR alterations associated with intrinsic or acquired resistance to 3rd generation EGFR TKIs, while sparing wild type EGFR. This broad spectrum coverage of resistance mutations in conjunction with CNS penetration properties allows BDTX-1535 to address a key unmet medical need in EGFR mutant lung cancer. BDTX-1535 is currently under phase I clinical investigation (NCT05256290). Conflict of interest: Ownership: Black Diamond Therapeutics

1109P Amivantamab vs real-world (RW) therapy in Japanese patients with advanced non-small cell lung cancer (aNSCLC) epidermal growth factor receptor (EGFR) exon-20 insertion mutation (E20i)

E20i, the 3rd most common EGFR mutation, is largely resistant to EGFR tyrosine kinase inhibitors (TKIs). In the single-arm CHRYSALIS study, aNSCLC E20i patients showed durable responses to amivantamab, an EGFR-MET bispecific antibody targeting tumors with activating and resistant EGFR mutations. This study compares the effectiveness of amivantamab to current systemic anti-cancer therapies in RW practice in Japan.

Audit of Molecular Mechanisms of Primary and Secondary Resistance to Various Generations of Tyrosine Kinase Inhibitors in Known Epidermal Growth Factor Receptor-Mutant Non-small Cell Lung Cancer Patients in a Tertiary Centre

AimsPresently, three generations of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are approved against oncogene addicted EGFR-mutant non-small cell lung cancer (NSCLC). Patients with actionable EGFR mutations invariably develop resistance. This resistance can be intrinsic (primary) or acquired (secondary). Materials and methodsThis was a retrospective study carried out between January 2016 and April 2021 analysing 486 samples of NSCLC for primary and secondary resistance to first- (erlotinib, gefitinb), second- (afatinib) and/or third-generation (osimertinib) TKIs in EGFR-mutant NSCLCs by next generation sequencing (NGS). Tissue NGS was carried out using the Thermofischer Ion Torrent™ Oncomine™ Focus 52 gene assay; liquid biopsy NGS was carried out using the Oncomine Lung Cell-Free Total Nucleic Acid assay. All cases were previously tested for a single EGFR gene with the Therascreen® EGFR RGQ PCR kit. ResultsThe results were divided into four groups: (i) group 1: primary resistance to first- and/or second-generation TKIs. This group, with 21 cases, showed EGFR exon 20 insertions, dual, complex mutations and variant of unknown significance, de novo MET gene amplification besides other mutations. (ii) Group 2: primary resistance to third-generation TKIs. This group showed two cases, with one showing dual EGFR mutation (L858R and E709A) and EGFR gene amplification. (iii) Group 3: secondary resistance to first- and second-generation TKIs. This group had 27 cases, which were previously reported negative for EGFR T790M by single gene testing. Significant findings were MET gene amplification in four cases, with one also showing MET exon 14 skipping mutation. Three cases showed small cell change and one showed loss of primary mutation. (iv) Group 4: secondary resistance to third-generation TKIs. The latter group was further subgrouped into group 4A: secondary resistance to osimertinib (third-generation TKI) when offered as second-line therapy after first- and second-generation TKIs on detection of T790M mutation. This group had 15 cases. EGFR T790M mutation was lost in 10 (10/15; 67%) cases and was retained in five cases. Patients with T790M loss experienced early resistance (6.9 months versus 12.6 months mean, P = 0.0024) compared with cases that retained T790M. Two cases gained MET amplification as the resistance mechanisms. Other mutations that were found when EGFR T790M was lost were in FGFR3, KRAS, PIK3CA, CTNNB1, BRAF genes. One case had EML4-ALK translocation. Two cases showed driver EGFR deletion 19, retained T790M and C797S mutation in Cis form. Group 4B: secondary resistance to osimertinib (when given as first-line therapy) in EGFR-mutant NSCLC. This group had three cases. The duration of osimertinib treatment ranged from 11 to 17 months. Two patients showed additional C797S mutation along with primary EGFR mutation. ConclusionThis study shows the wide spectrum of primary and secondary EGFR resistance mechanisms to first, second and third generation of TKIs and helps us to identify newer therapeutic targets that could carry forward the initial advantage offered by EGFR TKIs.

Abstract 6217: TP53 loss with whole genome doubling mediates heterogeneous intra-patient therapy response in EGFR-driven lung adenocarcinoma: A TRACERx study

Abstract Introduction: Mutations in the epidermal growth factor receptor (EGFR) are often found in never-smokers who develop lung adenocarcinoma (LUAD) and resistance to receptor-targeted tyrosine kinase inhibitors (TKIs) generally occurs within five years of treatment. Mixed responses, where individual tumor lesions within the same patient respond differently to treatment, contribute to early treatment failure and indicate the involvement of multiple genomic alterations. TP53 loss of function has been associated with both tolerance to chromosomal instability (CIN) and with shortened progression free survival in EGFR-driven tumors. The aim of this study was to investigate the hypothesis that CIN, together with loss of p53 function, may lead to diverse genotypes that underlie the mixed responses observed in EGFR-driven LUAD. Experimental Procedures: We used genetically engineered mouse models (GEMMs), driven by EGFR with or without concomitant Trp53 loss and human isogenic cell lines to investigate cellular evolution and the effect of whole genome doubling on targeted therapy responses and mechanisms of resistance. Next generation sequencing and shallow whole genome single cell analyses, together with longitudinal imaging analysis from the Aura clinical trials (AURA2, AURA3 and the AURA extension cohort, Identifiers: NCT02094261, NCT02151981 and NCT01802632) was used to investigate the effect of p53 loss on tumor evolution. Results: EGFR mutant tumors with clonal Trp53 loss or TP53 pathway disruption displayed increased Weighted Genome Integrity Index (wGII) and higher cell to cell variation in both the mouse and TRACERx data sets. We found that TP53 loss of function increased the incidence of mixed responses and resistance to targeted therapy in both mouse and human tumors leading to early treatment failure and reduced survival. Whole-exome sequencing (median depth of 92x, range: 58-169x) of nine erlotinib-resistant EGFR mouse tumors identified four EGFR bypassing mutations (oncogenic KRAS mutations; Q61H, Q61R, and two G12D mutations) and one likely driver mutation in FGFR2 (C286R). We could only identify one known resistance associated mutation, EGFRT790M, in EGFR mutant tumors with concomitant loss of Trp53. In depth analysis revealed no major copy number differences in treatment naÏve vs resistant EGFR mutant tumors. In contrast, 70% of all tumors with concomitant Trp53 loss had amplified a region of mouse chromosome 7, harboring MET and BRAF. Investigating an isogenic EGFR/TP53 mutant cell model system revealed whole genome doubling as advantageous in overcoming the selection pressure induced by targeted therapy. Conclusion: We find that loss of TP53 in the context of mutated EGFR leads to an altered and plastic genomic landscape, with multiple copy number changes, which in turn facilitates therapy resistance. Citation Format: Sebastijan Hobor, Maise Al Bakir, Marcin Skrzypski, Alexander M. Frankell, Bjorn Bakker, Thomas B. Watkins, Aleksandra Markovets, Jonathan R. Dry, Andrew P. Brown, Jasper van der Aart, Dahmane Oukrif, Marco Novelli, Matthew J. Renshaw, William Hill, Hilda van den Bos, Diana C. Spierings, Juliann Chmielecki, Carl Barrett, Kevin Litchfield, Elza de Bruin, Floris Foijer, Karen H. Vousden, TRACERx consortium, Robert E. Hynds, Crispin T. Hiley, Nnennaya Kanu, Simone Zaccaria, Eva C. Gronroos, Charles Swanton. TP53 loss with whole genome doubling mediates heterogeneous intra-patient therapy response in EGFR-driven lung adenocarcinoma: A TRACERx study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6217.

Abstract P230: A phase 1/2 study of BLU-945, a highly potent and selective inhibitor of epidermal growth factor receptor (EGFR) resistance mutations, in patients with EGFR-mutant non-small cell lung cancer (NSCLC)

Abstract BACKGROUND Activating EGFR mutations such as exon 19 deletion (ex19del) and L858R mutations, exon 19 insertions (ex19ins), and point mutations L861Q, G719X, and S768I are oncogenic drivers in lung adenocarcinoma, the most common NSCLC subtype. Although EGFR-targeted therapies, including first-, second-, and third-generation tyrosine kinase inhibitors (TKIs), have improved outcomes in patients (pts) with EGFR-mutant (EGFRm) NSCLC, resistance to these drugs is inevitable. BLU-945 is an investigational fourth-generation EGFR TKI designed to suppress both activating and on-target resistance EGFR mutations, such as C797S and T790M. Preclinical data showed BLU-945 has nanomolar potency against EGFRm/T790M double and EGFRm/T790M/C797S triple mutants with >450-fold selectivity for these mutants over wild-type EGFR in biochemical and cellular assays, and demonstrated robust preclinical antitumor activity, including in intracranial tumors harboring these mutations, providing the therapeutic rationale for BLU-945 clinical development. METHODS BLU-945-1101 (NCT04862780) is an international, open-label, first-in-human, phase 1/2 study designed to evaluate safety, tolerability, and antitumor activity of BLU-945 in pts with EGFRm NSCLC. Key eligibility criteria include adults with pathologically confirmed metastatic NSCLC with an activating EGFR mutation per local assessment (including ex19del or L858R); Eastern Cooperative Oncology Group performance status 0–2; and previous treatment with ≥1 EGFR-targeted TKI. Pts with asymptomatic brain metastases and on stable doses of corticosteroids are eligible. Key exclusion criteria are any additional known primary driver alterations, including but not limited to pathologic aberrations of EGFR exon 20 (insertions), KRAS, BRAF V600E, NTRK1/2/3, HER2, ALK, ROS1, MET, or RET. Phase 1 primary endpoints are maximum tolerated dose, recommended phase 2 dose (RP2D), and safety. The phase 2 primary endpoint is overall response rate (ORR) by RECIST 1.1. Phase 1 secondary endpoints include ORR, duration of response (DOR), pharmacokinetics (PK), and pharmacodynamics (PD); phase 2 secondary endpoints include DOR, disease control rate (DCR), clinical benefit rate (CBR), progression free survival (PFS), overall survival (OS), time to intracranial progression and intracranial response rate, PK, PD, and safety. Phase 1 dose escalation (N≈60) will be conducted using Bayesian optimal interval design. In the phase 2 dose expansion (N≈61), pts will be enrolled into 3 groups based on mutation profile and treated at the RP2D: primary group 1 for pts with EGFR T790M and C797S (n≈37); exploratory group 2 for pts with EGFR T790M but not C797S (n≈12); exploratory group 3 for pts with EGFR C797S but not T790M (n≈12). Group 1 will use Simon’s 2-stage design to test the null hypothesis of ORR ≤20% against a 1-sided alternative of ≥40%. Pts may receive treatment until disease progression or unacceptable toxicity. Recruitment has started and approximately 30 sites will be open for enrollment across North America, Europe, and Asia. Citation Format: David Spigel, Koichi Goto, D. Ross Camidge, Yasir Elamin, Adrianus J. de Langen, Natasha B. Leighl, Anna Minchom, Zofia Piotrowska, David Planchard, Karen Reckamp, Faris Albayya, Jennifer Green, Sean Kim, Melinda Louie-Gao, Renata Sawtell, Alena Zalutskaya, Byoung Chul Co. A phase 1/2 study of BLU-945, a highly potent and selective inhibitor of epidermal growth factor receptor (EGFR) resistance mutations, in patients with EGFR-mutant non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P230.

Pilot Study of Dacomitinib for Patients With Metastatic EGFR-Mutant Lung Cancers With Disease Progression After Initial Treatment With Osimertinib

In this phase II study, patients who had progressed on first-line osimertinib were treated with dacomitinib 45 mg orally daily until disease progression or intolerability. The primary end point was objective response rate. We enrolled 12 patients. Two partial responses were documented (17% objective response rate; 95% CI, 5 to 45). The median progression-free survival was 1.8 months (95% CI, 1.6 to not reached). One patient with an original sensitizing EGFR G719A mutation and one patient without molecular testing available had partial responses, whereas 0 of the 3 patients with second-site acquired EGFR resistance mutations (two C797S and one G724S) met the response criteria. The patient with EGFR G719A has an ongoing response at 17 months, which exceeds prior time on osimertinib (11 months). In the first trial evaluating a second-generation EGFR TKI after first-line third-generation osimertinib, we found that dacomitinib after disease progression on osimertinib has limited benefit.