Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors Osimertinib Research Articles

Abstract 1945: Mechanisms of acquired resistance to EGFR tyrosine kinase inhibitor osimertinib and KRAS-G12C inhibitor sotorasib in lung cancer

Abstract A series of molecular targeted drugs have been developed for the treatment of non-small cell lung cancer (NSCLC) harboring driver gene alterations. Although the use of these drugs has substantially improved the clinical outcomes of patients with the genetically altered NSCLC, these patients ultimately develop resistance to the drugs. Various molecular mechanisms of resistance to the molecular target therapies have been reported, it is still a crucial challenge to overcome the drug resistance. Osimertinib, the most used third-generation EGFR tyrosine kinase inhibitor to target both common EGFR mutations and secondary T790M mutation, and sotorasib, a recently developed KRAS inhibitor to target KRAS G12C mutation, are no exception. In this study, we aimed to investigate the mechanisms of acquired resistance to osimertinib and sotorasib in NSCLC by profiling drug-resistant lung cancer cell lines, which were established from EGFR-mutant HCC827(del E756_A750) and KRAS G12C-mutant H23 through exposure to each of the molecular targeted drugs. Phospho-RTK array and western blot analyses revealed MET overexpression and phosphorylation in the osimertinib-resistant HCC827 (HCC827OR) as previous studies reported. Notably in our study, HCC827OR cells were incompletely sensitive to a selective MET inhibitor savolitinib without osimertinib, suggesting that HCC827OR partially lost its dependency on mutant EGFR and got addiction to MET signaling. When sotolasib was administered to the sotolasib-resistant H23 (H23SR) cells, KRAS-GTP, and the downstream ERK and AKT phosphorylation were suppressed. To identify novel mechanisms of the resistance, we performed epigenomic profiling of active enhancer in those cells and found a candidate transcription factor, at whose gene locus H3K27 acetylation signal was increased in H23SR cells compared to parent H23 cells. Immunoblotting showed that protein expression of the gene was indeed higher in H23SR cells than the parent cells. To confirm the involvement of this gene to the resistance, further investigation is warranted. Citation Format: Yuri Yagami, Takashi Sato, Hiroki Yamamoto, Masayuki Shirasawa, Yoshiro Nakahara, Watanabe Hideo, Naoki Katsuhiko. Mechanisms of acquired resistance to EGFR tyrosine kinase inhibitor osimertinib and KRAS-G12C inhibitor sotorasib in lung cancer [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 1945.

Targeting glucosylceramide synthase induces antiproliferative and proapoptotic effects in osimertinib-resistant NSCLC cell models

The EGFR tyrosine kinase inhibitor osimertinib has been approved for the first-line treatment of EGFR-mutated Non-Small Cell Lung Cancer (NSCLC) patients. Despite its efficacy, patients develop resistance. Mechanisms of resistance are heterogeneous and not fully understood, and their characterization is essential to find new strategies to overcome resistance. Ceramides are well-known regulators of apoptosis and are converted into glucosylceramides (GlcCer) by glucosylceramide synthase (GCS). A higher content of GlcCers was observed in lung pleural effusions from NSCLC patients and their role in osimertinib-resistance has not been documented. The aim of this study was to determine the therapeutic potential of inhibiting GCS in NSCLC EGFR-mutant models resistant to osimertinib in vitro and in vivo. Lipidomic analysis showed a significant increase in the intracellular levels of glycosylceramides, including GlcCers in osimertinib resistant clones compared to sensitive cells. In resistant cells, the GCS inhibitor PDMP caused cell cycle arrest, inhibition of 2D and 3D cell proliferation, colony formation and migration capability, and apoptosis induction. The intratumoral injection of PDMP completely suppressed the growth of OR xenograft models. This study demonstrated that dysregulation of ceramide metabolism is involved in osimertinib-resistance and targeting GCS may be a promising therapeutic strategy for patients progressed to osimertinib.

Real-world outcomes on platinum-containing chemotherapy for EGFR-mutated advanced nonsquamous NSCLC with prior exposure to EGFR tyrosine kinase inhibitors.

Front-line therapy with an EGFR tyrosine kinase inhibitor (TKI) is the standard of care for treating patients with advanced nonsquamous NSCLC with the common sensitizing EGFR exon 19 deletion and exon 21 L858R point mutations. However, EGFR TKI resistance inevitably develops. The optimal subsequent therapy remains to be identified, although platinum-containing chemotherapy regimens are often administered. Our objectives were to describe baseline characteristics, survival, and subsequent treatment patterns for patients with advanced nonsquamous NSCLC with EGFR exon 19 deletion or L858R mutation who received a platinum-based combination regimen after front-line EGFR TKI therapy. This retrospective study used a nationwide electronic health record-derived deidentified database to select adult patients with advanced nonsquamous NSCLC, evidence of EGFR exon 19 deletion or L858R mutation, and ECOG performance status of 0-2 who initiated platinum-containing chemotherapy, with or without concomitant immunotherapy, from 1-January-2011 to 30-June-2020 following receipt of any EGFR TKI as first-line therapy or, alternatively, a first- or second-generation EGFR TKI (erlotinib, afatinib, gefitinib, dacomitinib) as first-line therapy followed by the third-generation EGFR TKI osimertinib as second-line therapy. Data cut-off was 30-June-2022. The Kaplan-Meier method was used to estimate overall survival (OS) after initiation of pemetrexed-platinum (n=119) or any platinum-based combination regimen (platinum cohort; n=311). The two cohorts included two-thirds women (65%-66%) and 57%-58% nonsmokers; median ages were 66 and 65 years in pemetrexed-platinum and platinum cohorts, respectively. Median OS was 10.3 months (95% CI, 8.1-13.9) from pemetrexed-platinum initiation and 12.4 months (95% CI, 10.2-15.2) from platinum initiation; 12-month survival rates were 48% and 51%, respectively; 260 patients (84%) had died by the end of the study. The suboptimal survival outcomes recorded in this study demonstrate the unmet need to identify more effective subsequent treatment regimens for patients with EGFR-mutated advanced nonsquamous NSCLC after EGFR TKI resistance develops.

Effectiveness comparison of third-generation EGFR-TKI as initial and sequential therapy in adjuvant treatment for EGFR mutation-sensitive stage IIIA non-small cell lung cancer after surgery

IntroductionAlthough third-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) Osimertinib has been approved as adjuvant therapy for resected stage IIIA non-small cell lung cancer (NSCLC) with EGFR-sensitive mutations, the optimal treatment sequencing of EGFR-TKIs, particularly whether Osimertinib should be the initial or sequential therapy following the first-generation EGFR-TKIs remains uncertain. MethodsA retrospective analysis was conducted on a cohort of patients with EGFR-mutated stage IIIA NSCLC who received treatment with either first-generation EGFR-TKIs or Osimertinib (third-generation) alone, or in sequential combination, at a single institution. The data analysis involved using the Kaplan-Meier method, log-rank test, and Cox regression. ResultsOut of the total 148 patients with stage IIIA NSCLC included in the study, 76 individuals underwent treatment with either first-generation EGFR-TKIs (referred to as subgroup “1″) or exclusively Osimertinib (subgroup “0 + 3″), or a sequential combination of the two (subgroup “1 + 3″) following surgery. Both univariate and multivariate analyses demonstrated that there were no discernible disparities in terms of disease-free survival and overall survival between subgroup " 1″ and " 1 + 3,” nor between subgroup " 0 + 3″ and “1 + 3". ConclusionThe findings from this study indicate that the introduction of third-generation EGFR-TKI Osimertinib did not yield enhanced survival benefits when compared to the first-generation drug in patients with stage IIIA completely resected NSCLC who were administered EGFR-TKIs as part of their postoperative adjuvant treatment. Additionally, within the observed sample size of this cohort, the sequential use of Osimertinib alongside first-generation EGFR-TKI did not demonstrate superiority over using either the first-generation EGFR-TKI or Osimertinib alone in terms of postoperative survival.

Comparation of EGFR-TKI (EGFR tyrosine kinase inhibitors) combination therapy and osimertinib for untreated EGFR-mutated advanced non-small cell lung cancers: A systematic review and network meta-analysis.

EGFR-TKI (tyrosine kinase inhibitor) monotherapy has become the first-line treatment option for patients with EGFR-mutated non-small cell lung cancer (NSCLC). Prolonging the survival time, improving the progression-free survival of front-line treatment, and delaying the occurrence of drug resistance. At present, combination therapy is being widely used. Evaluate the therapeutic effect of TKI joint and Osimertinib drug therapy for positive patients with gene positive. Articles that met the inclusion criteria were searched through electronic databases. treatment emergent adverse events were summarized, and progression-free survival (PFS) and overall survival (OS) were calculated. Appropriate networks for different outcomes were created to incorporate all the evidence. Bayesian network-based multitreatment was used to compare the efficacy and specific toxicity of all treatment regimens. Fourteen eligible studies involving 2325 patients were included. Of these, 7 studies compared EGFR-TKI plus chemotherapy with EGFR-TKI alone, and 6 studies compared EGFR-TKI plus antiangiogenic therapy with EGFR-TKI alone. One study compared Osimertinib and GP, ER, EB, and GCP were more effective than SOC in PFS analysis; however, there was no significant difference between osimertinib and the other 4 combination regimens. The cumulative probabilities of being the most efficacious treatments were (PFS, OS, treatment emergent adverse events): O (73%, 16%, 0%, 0%), GCP (14%, 64%, 10%, 16%), GP (2%, 17%,8%), and EB (3%, 3%, 8%), ER (5%, NA, 4%);GA(1%, NA, 69%). Osimertinib has the lowest side effects and provides better PFS first-line treatment in advanced EGFR-mutated NSCLC.GCP is the best regimen for OS, but its toxicity limits its application, and it may be the first choice for patients with higher survival requirements.

A pilot study of anlotinib with third-generation epidermal growth factor receptor tyrosine kinase inhibitors in untreated EGFR-mutant patients with advanced non-small cell lung cancer.

In recent years, osimertinib, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), has been recommended as a first-line treatment for EGFR-mutant advanced non-small cell lung cancer (NSCLC). A phase III study (AENEAS) to assess the efficacy and safety of aumolertinib, another third-generation EGFR-TKI, vs. gefitinib as a first-line treatment in patients with locally advanced or metastatic NSCLC harboring EGFR mutations has also achieved positive results. Despite the improvements in progression-free survival (PFS) and overall survival (OS) of third- vs. first-generation EGFR-TKIs, combined treatment strategies to postpone drug resistance and further prolong survival benefits remain to be explored. We conducted a nonrandomized phase II trial (ChiCTR2000035140) of an oral multitarget antiangiogenic TKI (anlotinib) with third-generation EGFR-TKIs (osimertinib or aumolertinib) in untreated patients with EGFR mutation and advanced NSCLC. Anlotinib and the third-generation EGFR-TKIs were orally administrated (anlotinib at a dose of 12 mg once every other day and osimertinib at 80 mg once daily or aumolertinib at 110 mg once daily). The primary end point of the study was the objective response rate (ORR). Secondary endpoints included the disease control rate (DCR), OS, PFS, and safety of the combined treatment. Enrollment was ceased due to treatment-related adverse events (trAEs) after 11 of 35 planned patients were treated. Among these 11 patients, two were lost to follow-up, and the treatment of five of the remaining nine patients was discontinued due to trAEs, including stomachache, rash, hyponatremia, pulmonary embolism, and interstitial pneumonia. AEs of grade 3 or worse were observed in five patients, but no treatment-related death occurred in these patients. Combining anlotinib and third-generation EGFR-TKIs in untreated EGFR-mutant patients with advanced NSCLC demonstrated significantly increased toxicity, suggesting that the combined treatment strategy was an inappropriate therapeutic choice in this setting.

Influence of germline variations in drug transporters ABCB1 and ABCG2 on intracerebral osimertinib efficacy in patients with non-small cell lung cancer.

Central nervous system (CNS) metastases are present in approximately 40% of patients with metastatic epidermal growth factor receptor-mutated (EGFRm+) non-small cell lung cancer (NSCLC). The EGFR-tyrosine kinase inhibitor osimertinib is a substrate of transporters ABCB1 and ABCG2 and metabolized by CYP3A4. We investigated relationships between single nucleotide polymorphisms (SNPs) ABCB1 3435C>T, ABCG2 421C>A and 34G>A, and CYP3A4∗22 and CNS treatment efficacy of osimertinib in EGFRm+NSCLC patients. Patients who started treatment with osimertinib for EGFRm+NSCLC between November 2014 and June 2021 were included in this retrospective observational multicentre cohort study. For patients with baseline CNS metastases, the primary endpoint was CNS progression-free survival (CNS-PFS; time from osimertinib start until CNS disease progression or death). For patients with no or unknown baseline CNS metastases, the primary endpoint was CNS disease-free survival (CNS-DFS; time from osimertinib start until occurrence of new CNS metastases). Relationships between SNPs and baseline characteristics with CNS-PFS and CNS-DFS were studied with competing-risks survival analysis. Secondary endpoints were relationships between SNPs and PFS, overall survival, severe toxicity, and osimertinib pharmacokinetics. From 572 included patients, 201 had baseline CNS metastases. No SNP was associated with CNS-PFS. Genotype ABCG2 34GA/AA and/or ABCB1 3435CC --present in 35% of patients-- was significantly associated with decreased CNS-DFS (hazard ratio 0.28; 95% CI 0.11-0.73; p=0.009) in the multivariate analysis. This remained significant after applying a Bonferroni correction and internal validation through bootstrapping. ABCG2 421CA/AA was related to more severe toxicity (27.0% versus 16.5%; p=0.010). ABCG2 34G>A and ABCB1 3435C>T are predictors for developing new CNS metastases during osimertinib treatment, probably because of diminished drug levels in the CNS. ABCG2 421C>A was significantly related with the incidence of severe toxicity. Pre-emptive genotyping for these SNPs could individualize osimertinib therapy. Addition of ABCG2 inhibitors for patients without ABCG2 34G>A should be studied further, to prevent new CNS metastases during osimertinib treatment. No funding was received for this trial.

Tackling Osimertinib Resistance in EGFR-Mutant Non-Small Cell Lung Cancer.

The current landscape of targeted therapies directed against oncogenic driver alterations in non-small cell lung cancer (NSCLC) is expanding. Patients with EGFR-mutant NSCLC can derive significant benefit from EGFR tyrosine kinase inhibitor (TKI) therapy, including the third-generation EGFR TKI osimertinib. However, invariably, all patients will experience disease progression with this therapy mainly due to the adaptation of cancer cells through primary or secondary molecular mechanisms of resistance. The comprehension and access to tissue and cell-free DNA next-generation sequencing have fueled the development of innovative therapeutic strategies to prevent and overcome resistance to osimertinib in the clinical setting. Herein, we review the biological and clinical implications of molecular mechanisms of osimertinib resistance and the ongoing development of therapeutic strategies to overcome or prevent resistance.

Abstract 3864: Targeting IL-6/STAT3 signaling in EGFR-mutant drug tolerant persister cells

Abstract While the majority of epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer (NSCLC) patients initially respond to treatment with an EGFR tyrosine kinase inhibitor (TKI), most will eventually develop acquired resistance to these agents. The evolution of tumor cells with acquired resistance to targeted agents initially involves the persistence of a drug-tolerant subpopulation of tumor cells which display a transient and flexible resistant state. These persister cells can remain quiescent for prolonged periods of time, but eventually give rise to fully drug resistant tumor cells that resume growth and metastatic spread. The signaling pathways that allow persister cells to remain viable or to re-activate expansive growth are poorly understood. We and others have reported that EGFR TKI resistance that occurs independent of secondary EGFR mutations or MET amplification is associated with an epithelial to mesenchymal transition (EMT). Our analysis of tumor cells that had undergone EMT-mediated resistance to the EGFR TKI osimertinib revealed that interleukin-6 (IL-6) was highly upregulated in resistant cells as compared to parental cells. We find that in the setting of EGFR mutant NSCLC, IL-6 suppresses the anti-tumor cell activity of T cells and NK cells. To assess the role of IL-6 in the early events of EGFR TKI resistance, we generated drug-tolerant persister cells by treating EGFR mutant HCC4006 and HCC827 NSCLC cells with the EGFR TKI osimertinib for 10 days and then assessed IL-6 expression. We observed that IL-6 was upregulated at both the RNA and protein levels in EGFR-TKI persister cells as compared to parental cells. While the cell surface expression of IL6R was not significantly increased in EGFR-TKI persister cells as compared to parental cells, we observed increased secretion of soluble IL6R in persister cells by ELISA assay. We next assessed changes in protein expression and activation in drug tolerant persister cells by reverse phase protein array (RPPA) and observed that p-STAT3, a key component of the IL-6 signaling pathway, was significantly elevated in persister cells as compared parental cells or cells treated with osimertinib for 24 hours. Using genetically engineered mouse models (GEMM) of EGFRL858R mutant lung cancer, we also observed a similar upregulation of both IL-6 and p-STAT3 expression at the RNA and protein levels in EGFR-mutant tumors treated with osimertinib for 2 or 4 weeks. Additionally, circulating levels of IL-6 also are elevated in EGFRL858R GEMMs treated with osimertinib for 2 or 4 weeks. Collectively, our data indicates that upregulation of IL-6 is an early event in the evolution of drug resistance. Given the role of IL-6 in promoting EGFR TKI resistance, further studies investigating whether targeting of IL-6 signaling may impair the survival or outgrowth of persister populations are warranted. Citation Format: Sonia A. Patel, Monique Nilsson, Yan Yang, Li Shen, Jing Wang, Alissa Poteete, Xiaoxing Yu, Xiaoyang Ren, Xiuning Le, John Heymach. Targeting IL-6/STAT3 signaling in EGFR-mutant drug tolerant persister cells. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3864.

Osimertinib as neoadjuvant therapy in patients with EGFR-mutant resectable stage II-IIIB lung adenocarcinoma (NEOS): A multicenter, single-arm, open-label phase 2b trial

ObjectivesOsimertinib, a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), has been approved for EGFR-mutant non-small-cell lung cancer (NSCLC). We aimed to evaluate the efficacy and safety of neoadjuvant osimertinib in patients with EGFR-mutant resectable locally advanced NSCLC. Materials and MethodsThis single-arm, phase 2b trial (ChiCTR1800016948) was conducted at six centers in mainland China. Patients with a measurable stage IIA-IIIB (T3-4 N2) lung adenocarcinoma and EGFR exon 19 and/or 21 mutations were enrolled. The patients were treated with osimertinib 80 mg orally once per day for six weeks, followed by surgical resection. The primary endpoint was the objective response rate (ORR) assessed according to the Response Evaluation Criteria In Solid Tumors version 1.1. ResultsBetween October 17, 2018, and June 08, 2021, 88 patients were screened for eligibility. Forty patients were enrolled and treated with neoadjuvant osimertinib therapy. The ORR was 71.1 % (27/38) (95 % confidence interval: 55.2–83.0) in 38 patients who completed the 6-week osimertinib treatment. Thirty-two patients underwent surgery, and 30 (93.8 %) underwent successful R0 resection. Thirty (75.0 %) of 40 patients had treatment-related adverse events during neoadjuvant treatment, and three (7.5 %) had treatment-related adverse events of grade 3. The most common treatment-related adverse events were rash (n = 20 [50 %]), diarrhea (n = 12 [30 %]), and oral ulceration (n = 12 [30 %]). ConclusionsThe third-generation EGFR TKI osimertinib, with satisfying efficacy and acceptable safety profile, could be a promising neoadjuvant therapy in patients with resectable EGFR-mutant NSCLC.

CD73 Inhibitor Oleclumab Plus Osimertinib in Previously Treated Patients With Advanced T790M-Negative EGFR-Mutated NSCLC: A Brief Report

IntroductionCD73 is overexpressed in EGFR-mutated NSCLC and may promote immune evasion, suggesting potential for combining CD73 blockers with EGFR tyrosine kinase inhibitors (TKIs). This phase 1b-2 study (NCT03381274) evaluated the anti-CD73 antibody oleclumab plus the third-generation EGFR TKI osimertinib in advanced EGFR-mutated NSCLC. MethodsPatients had tissue T790M-negative NSCLC with TKI-sensitive EGFR mutations after progression on a first- or second-generation EGFR TKI and were osimertinib naive. They received osimertinib 80 mg orally once daily plus oleclumab 1500 mg (dose level 1 [DL1]) or 3000 mg (DL2) intravenously every 2 weeks. Primary end points included safety and objective response rate by Response Evaluation Criteria in Solid Tumors version 1.1. ResultsBy July 9, 2021, five patients received DL1 and 21 received DL2. Of these patients, 60.0% and 85.7% had any-grade treatment-related adverse events (TRAEs) and 20.0% and 14.3% had grade 3 TRAEs, respectively. No dose-limiting toxicities, serious TRAEs, or deaths occurred. Four patients were T790M positive on retrospective circulating tumor DNA (ctDNA) testing; three had objective partial responses. In patients who were T790M negative in tumor and ctDNA, objective response rate was 25.0% at DL1 and 11.8% at DL2 (all partial responses); response durations at DL2 were 14.8 and 16.6 months. In patients receiving DL2, excluding those who were T790M positive by ctDNA, median progression-free survival was 7.4 months, and median overall survival was 24.8 months. DL2 was the recommended phase 2 dose. ConclusionsOleclumab plus osimertinib was found to have moderate activity with acceptable tolerability in previously treated patients with advanced EGFR-mutated NSCLC.

Rationale and protocol design of a phase II study of first-line osimertinib treatment for patients with poor performance status and EGFR mutation-positive non-small cell lung cancer (OPEN/TORG2040)

BackgroundCancer chemotherapy indications for patients with poor performance status and advanced lung cancer are limited. Molecular targeted drugs, including epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors, can be used in patients with poor performance status owing to their high efficacy and safety. The third-generation EGFR-tyrosine kinase inhibitor osimertinib has demonstrated effectiveness in the initial treatment of advanced EGFR mutation-positive non-small cell lung cancer in patients with good performance status; however, no evidence exists of the drug’s effectiveness in patients with poor performance status in a prospective study. We designed a study that aims to investigate the efficacy and safety of first-line osimertinib treatment in patients with advanced non-small cell lung cancer harboring sensitive EGFR mutations and with poor performance status.MethodsThe OPEN/TORG2040 study is a multicenter, single-arm, phase II trial for patients with unresectable, advanced EGFR mutation-positive non-small cell lung cancer with a poor performance status (≥ 2). Eligible patients will receive osimertinib until disease progression or unacceptable toxicity. The primary endpoint is the objective response rate of the first-line osimertinib treatment. Considering a threshold value of 45%, expected value of 70% for objective response rate, one-sided significance level of 5%, statistical power of 80%, and ineligible patients, the sample size was set to 30. The secondary endpoints are disease control rate, performance status improvement rate, and safety and patient-reported outcomes using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core Quality of Life Questionnaire and Lung Cancer 13. Time to treatment failure, progression-free survival, and overall survival will also be assessed.DiscussionOur study can determine the clinical benefits of osimertinib treatment in patients with poor performance status, since the clinical outcomes of patients with EGFR mutation-positive non-small cell lung cancer with poor performance status treated with this drug as a first-line treatment have not been sufficiently evaluated.Trial registrationJapan Registry of Clinical Trials: jRCTs041200100 (registration date: February 12, 2021).

Ras-Related Protein Rab-32 and Thrombospondin 1 Confer Resistance to the EGFR Tyrosine Kinase Inhibitor Osimertinib by Activating Focal Adhesion Kinase in Non-Small Cell Lung Cancer.

Simple SummaryOsimertinib is a third-generation EGFR tyrosine kinase inhibitor and the standard of care therapy for non-small cell lung cancer patients harboring EGFR-activating mutations. However, even for patients treated with osimertinib, resistance inevitably occurs leading to disease progression. Here, we utilized two osimertinib-resistant cell lines and investigated their RNA profiles. We found that Ras-related protein Rab-32 (RAB32) and thrombospondin 1 (THBS1) were upregulated and associated with resistance in osimertinib-resistant cells as well as in liquid biopsies from patients with disease progression following osimertinib treatment. Moreover, we found RAB32 and THBS1 to be mechanistically linked to activation of the focal adhesion pathway where combination of osimertinib with a FAK inhibitor resulted in a synergistic suppression of viability of osimertinib-resistant cells. Our findings propose a potential therapeutic strategy for overcoming acquired resistance to osimertinib in non-small cell lung cancer.Treatment with the tyrosine kinase inhibitor (TKI) osimertinib is the standard of care for non-small cell lung cancer (NSCLC) patients with activating mutations in the epidermal growth factor receptor (EGFR). Osimertinib is also used in T790M-positive NSCLC that may occur de novo or be acquired following first-line treatment with other EGFR TKIs (i.e., gefitinib, erlotinib, afatinib, or dacomitinib). However, patients treated with osimertinib have a high risk of developing resistance to the treatment. A substantial fraction of the mechanisms for resistance is unknown and may involve RNA and/or protein alterations. In this study, we investigated the full transcriptome of parental and osimertinib-resistant cell lines, revealing 131 differentially expressed genes. Knockdown screening of the genes upregulated in resistant cell lines uncovered eight genes to partly confer resistance to osimertinib. Among them, we detected the expression of Ras-related protein Rab-32 (RAB32) and thrombospondin 1 (THBS1) in plasmas sampled at baseline and at disease progression from EGFR-positive NSCLC patients treated with osimertinib. Both genes were upregulated in progression samples. Moreover, we found that knockdown of RAB32 and THBS1 reduced the expression of phosphorylated focal adhesion kinase (FAK). Combination of osimertinib with a FAK inhibitor resulted in synergistic toxicity in osimertinib-resistant cells, suggesting a potential therapeutic drug combination for overcoming resistance to osimertinib in NSCLC patients.

Abstract 1093: BRD9 inhibition overcomes epithelial to mesenchymal transition (EMT)-associated tyrosine kinase inhibitor (TKI) tolerance in epidermal growth factor receptor (EGFR) mutant lung cancer

Abstract Advanced lung cancer patients that present with activating mutations in the epidermal growth factor receptor (EGFR) are treated with EGFR tyrosine kinase inhibitors (EGFR TKIs). While initially effective, all patients eventually develop therapeutic resistance and experience disease progression. Strategies to prevent EGFR TKI resistance are needed to improve patient outcomes. We chronically exposed H1975 cells (EGFR-L858R/T790M) to EGFR TKI osimertinib to study emergence of resistance. H1975 cells that were expanded under drug treatment (designated H1975OR) acquired an EMT phenotype and were re-sensitized to EGFR TKI upon prolonged drug withdrawal. These features led us to classify H1975OR as a model of drug tolerance rather than a model of stable drug resistance. Bulk RNA-sequencing revealed significant dysregulation of chromatin modifying genes in H1975OR. Bromodomain containing protein 9 (BRD9) was among the set of significantly upregulated chromatin regulators and was selected for further investigation as a mediator of drug tolerance. Although BRD9 is known to control stemness and EMT, its role in promoting EMT-associated TKI resistance is unknown. To test the contribution of BRD9 to EGFR TKI tolerance, pharmacological inhibition of BRD9 by the selective inhibitor, I-BRD9 significantly increased sensitivity to TKI in models with EMT phenotypes (IC50 reduced 3-4 fold). In contrast, I-BRD9 did not affect TKI sensitivity in two models where EGFR TKI resistance was genetically fixed. To gain mechanistic insights, H1975OR cells were treated with osimertinib +/-I-BRD9 and subjected to RNA-sequencing. Combination of osimertinib with I-BRD9 resulted in a significant decrease in EMT-related genes, including MMP9, Zeb2, PDGFRb and IL6. Further, use of I-BRD9 in these models diminished the mesenchymal phenotype, as measured in cell invasion assays. Genetic knockdown of BRD9 via shRNA phenocopied effects of I-BRD9 treatment, supporting BRD9 as the therapeutic target of I-BRD9 in our cell line models. To further establish a role for BRD9 in the emergence of drug tolerant cells, we exposed treatment naïve H1975 cells to EGFR TKI ± I-BRD9. I-BRD9 significantly decreased the size of the EGFR TKI tolerant population. In time course studies, I-BRD9 also delayed onset of TKI resistance. In conclusion, our data identifies BRD9 as a novel mediator of EMT-associated EGFR-TKI tolerance in EGFR-mutant lung cancer. Our data further implicates BRD9 inhibition as a novel strategy to delay the emergence of drug tolerant cells that eventually give rise to stable drug resistance. This work was supported by the Roswell Park Alliance Foundation and National Cancer Institute (NCI) grant P30CA016056 involving the use of Roswell Park Comprehensive Cancer Center’s Genomics and Bioinformatics Shared Resources. Citation Format: Hannah Calkins, Tatiana Shaurova, David W. Goodrich, Mukund Seshadri, Candace S. Johnson, Pamela A. Hershberger. BRD9 inhibition overcomes epithelial to mesenchymal transition (EMT)-associated tyrosine kinase inhibitor (TKI) tolerance in epidermal growth factor receptor (EGFR) mutant lung cancer [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 1093.

Abstract 548: EGFR CAR-NK cells demonstrate potent activity against EGFR TKI resistant NSCLC

Abstract The leading cause of cancer-related deaths in the US is non-small cell lung cancer (NSCLC), and about 10-15% of NSCLC cases harbor EGFR activating mutations. While these patients are initially responsive to EGFR tyrosine kinase inhibitors (TKIs), they eventually experience progression and develop acquired TKI resistance. Currently, there are no approved therapies for NSCLC patients with acquired resistance to the third-generation EGFR TKI osimertinib (OSI). Moreover, EGFR-TKI resistant NSCLCs are refractory to immune checkpoint inhibitors. Therefore, novel treatment strategies are urgently needed. Chimeric antigen receptors (CARs) have been used to enhance the anti-tumor activity of immune effector cells. Here, we developed CAR-based therapies targeting EGFR as a novel strategy to overcome immune suppression and target EGFR TKI-resistant NSCLC. We designed multi-generational EGFR CAR constructs and transduced them into T and natural killer (NK) cells to generate CAR-T and CAR-NK cells, respectively. We then evaluated their activity against NSCLC cell lines in vitro using firefly luciferase assays. EGFR CAR-T and CAR-NK cells showed potent cytotoxicity against NSCLC cells expressing EGFR including EGFR wild-type and mutant NSCLCs, as well as NSCLC cells with acquired resistance to OSI. However, EGFR CAR-T cells showed decreased killing activity against OSI-resistant NSCLC cells compared to their parental cells. In contrast, EGFR CAR-NK cells showed stronger cytotoxicity against NSCLC with acquired OSI resistance as compared to parental cells. Transcriptomic analysis revealed that NSCLC cells with acquired resistance to TKI had undergone epithelial-mesenchymal transition and had downregulated expression of genes related to antigen presentation and upregulated expression of B7-H6 (NCR3LG1), which have been reported to be associated with increased responsiveness to NK cells. Moreover, treatment of TKI resistant cells with OSI resulted in upregulation of cell surface EGFR and potentiated CAR-NK cells-mediated killing. TGF-β is a critical immune-suppressive cytokine. We found that EGFR-TKI resistant NSCLC cells elaborated expression of TGF-β as compared to parental cells. Blockade of the TGF-β pathway using galunisertib significantly enhanced the activity of EGFR CAR-NK cells against OSI-resistant NSCLC cells. Next, we engineered the dominant-negative TGF-β receptor II (DNTGFBRII) into our EGFR CAR constructs. The expression of DNTGFBRII inhibited the phosphorylation of SMAD2 and the downregulation of granzyme B and perforin induced by TGF-β. DNTGFBRII-CAR-NK cells showed higher killing activity against OSI-resistant NSCLC cells and were resistant to TGF-β-mediated immunosuppression. In conclusion, EGFR CAR-NK cells show significant anti-tumor activity to EGFR TKI-resistant NSCLC cells, and the cytotoxicity is enhanced in combination with OSI treatment and blockade of the TGF-β pathway. Citation Format: Yan Yang, Monique Nilsson, Sonia Patel, Jacqulyne Robichaux, Alissa Poteete, Xiaoxing Yu, Fahao Zhang, Simon Heeke, Yu Qian, Junqin He, John Heymach. EGFR CAR-NK cells demonstrate potent activity against EGFR TKI resistant NSCLC [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 548.

Abstract 5364: The TEAD autopalmitoylation inhibitor VT3989 improves efficacy and increases durability of efficacy of osimertinib in preclinical EGFR mutant tumor models

Abstract The Hippo-YAP/TAZ pathway is involved in the regulation of cell proliferation, survival, and cell migration. The major effectors of the Hippo pathway are the TEAD transcription factors, which become transcriptionally activated upon YAP/TAZ binding. Genetic alterations of pathway components have been reported in a variety of human malignancies, resulting in YAP/TAZ constitutive nuclear localization and TEAD activation. The TEAD transcription factors have been shown to autopalmitoylate, and palmitoylation is required for its interaction with YAP/TAZ and hence activation of transcriptional activity. We have identified potent, selective, and orally available small molecule compounds that directly interact with TEAD and block its autopalmitoylation (Tang et al, 2021, Mol Cancer Ther. 20(6):986-998). These TEAD inhibitors disrupt YAP/TAZ-TEAD protein interaction, suppress TEAD transcriptional activity, and selectively block proliferation of NF2-deficient mesothelioma in vitro and inhibit NF2 mutant xenograft tumor growth in vivo. Nuclear YAP accumulation and functional requirement have also been linked to resistance to targeted therapies and cancer relapse in BRAF-mutant, KRAS-mutant, EGFR-mutant, and ALK-rearranged non-small cell lung cancers (NSCLC). Hence, as TEAD transcription factors are the main drivers for YAP/TAZ recruitment to chromatin, we evaluated the effect of our TEAD inhibitor VT3989, currently in clinical testing, on emerging drug tolerant persistent cancer cells and drug resistance during EGFR-tyrosine kinase inhibitor osimertinib treatment in combination studies. In in vitro cell proliferation assays, VT3989 showed strong to very strong synergy in combination with osimertinib in several EGFR mutant NSCLC cell lines tested. In vivo, we observed strong VT3989 and osimertinib combination effect in NCI-H1975 and HCC827 cell line-derived xenograft models. We also tested the combination in several EGFR mutant NSCLC patient-derived xenograft models and demonstrated that the addition of VT3989 enhanced the efficacy of osimertinib and delayed tumor regrowth compared to osimertinib alone. Citation Format: Tracy T. Tang, Leonard Post. The TEAD autopalmitoylation inhibitor VT3989 improves efficacy and increases durability of efficacy of osimertinib in preclinical EGFR mutant tumor models [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 5364.

An exploration of the clinical progression models of osimertinib in the treatment of advanced EGFR-mutant non-small cell lung cancer.

BackgroundClassifying the progression pattern had been proved to be momentous for predicting efficacy and guiding treatment in the 1st/2nd generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), while lack evidence in the 3rd generation EGFR-TKIs. This study aimed to classify tumor progression of osimertinib in EGFR+ advanced non-small cell lung cancer (NSCLC), exploring the characteristics and the clinical significance of each progression pattern.MethodsAfter screening 1,125 lung cancer patients, 168 EGFR T790M+ advanced patients using osimertinib were enrolled and divided into two groups and five clinical progression models according to the time course of the tumor progression. The prognosis and characteristics, such as gender, age, metastases, of each model were analyzed and compared by Kaplan-Meier method, t-test, and linear regression.ResultsComplete follow-up data were available for 117 of the 168 patients. Progressive disease (PD) occurred in 89 patients at an average onset of 6.59 months since using osimertinib, with 79.78% of patients experiencing enlargement of some preexisting lesions before PD. Among the five progression models, the ‘Rapid Enlargement’ (10.11%) model, the ‘Rapid New Lesion’ model (10.11%), the ‘Delayed Enlargement’ model (29.21%), the ‘Delayed New Lesion’ model (15.73%), and the ‘Non-targeted Enlargement’ model (34.83%), the ‘Non-targeted Enlargement’ model had the worst prognosis, with a median progression-free survival (mPFS) of 7.1 months (P=0.046). The mPFS of other models was similar, with the largest difference in the time interval between the beginning of osimertinib treatment to the first appearance of target lesion enlargement (Tm-e). Smoking history (P=0.046) and the location of the initial (P=0.048), enlarged (P=0.003), and progressive lesions (P=0.002) affected the progression models, while gender, age, and treatment lines had no effect. The Tm-e was related to the overall disease control time with a correlation coefficient of 0.667 (P=0.000). The appearance of a malignant pleural effusion had an impact on progression.ConclusionsWe tried to create a classification system for describing the failure of the third-generation EGFR-TKI osimertinib including two groups, subdivided into five progression models based on the time course of tumor lesion changes. The system might be conducive to predict the prognosis and be potential to assist in selecting subsequent treatment strategies.

Osimertinib and routine practice: the experience of the drug application in different clinical situations in case of metastatic non-small cell lung cancer with an EGFR mutation. Case report

After the introduce of new treatment options is always important to see how the results of the registered studies will be putted into routine clinical practice. Clinical studies help to assess the efficacy and safety of therapy and to conduct the objective comparison of the current standard of treatment. However, it is impossible to take into account all the variety of situations that oncologists can face in their daily work. Nowadays, the use of targeted therapy in the presence of the specific genetic disorders, in particular, driver mutations in the epidermal growth factor receptor (EGFR) gene, is an integral part of the management of patients with advanced non-small cell lung cancer (NSCLC). The first EGFR tyrosine kinase inhibitors (TKIs) have significantly changed our possibility of the treatment in this group of patients, and today we are already using the third-generation EGFR TKIs. The review analyzes the experience of using the third-generation EGFR TKIs osimertinib, through the prism of questions, asking by the practitioners: evaluation of the efficacy of treatment in routine practice, the management of difficult patients, in particular, the patients with bone and brain metastases, the patients with multiple primary tumors, the management tactics of patient taking into account the COVID-19 pandemic and related treatment interruptions. The literature and international experience review is completed by clinical cases from different regions of the Russian Federation.

Development and validation of a new liquid chromatography-tandem mass spectrometry assay for the simultaneous quantification of afatinib, dacomitinib, osimertinib, and the active metabolites of osimertinib in human serum

Reports on the therapeutic drug monitoring (TDM) of second- and third-generation epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) in non-small cell lung cancer patients are limited and are required to improve the safety of EGFR-TKI therapy. Some EGFR-TKIs have active metabolites with similar or higher potency compared with the parent compounds; thus, monitoring the parent compound as well as its active metabolites is essential for truly effective TDM. In this study, we developed and validated a method that simultaneously quantifies second- and third-generation EGFR-TKIs (afatinib, dacomitinib, and osimertinib) and the active metabolites of osimertinib, AZ5104 and AZ7550, in the human serum using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The clinical application of the method was also evaluated. The analytes were extracted from a 100 μL serum sample using a simple protein precipitation method and analyzed using LC-MS/MS. Excellent linearity of calibration curves was observed at ranges of 2.5–125.0 ng/mL for afatinib, 2.5–125.0 ng/mL for dacomitinib, 4.0–800.0 ng/mL for osimertinib, 1.0–125.0 ng/mL for AZ5104, and 2.5–125.0 ng/mL for AZ7550. The precision and accuracy were below 14.9% and within ± 14.9% of the nominal concentrations, respectively. The mean recovery was higher than 94.7% and the coefficient of variation (CV) was lower than 8.3%. The mean internal-standard normalized matrix factors ranged from 94.6 to 111.9%, and the CVs were lower than 9.7%. This analytical method met the acceptance criteria of the U.S. Food and Drug Administration guidelines. The method was also successfully applied to the analysis of 45 clinical samples; it supports the efficient and valuable analysis for TDM investigations of EGFR-TKIs.

33P A literature review of Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) caused by immune checkpoint inhibitors (ICIs), epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) and multikinase inhibitors (MKIs)

Stevens-Johnson syndrome (SJS)/ Toxic epidermal necrolysis (TEN) is the most severe type of drug eruption, characterized by blisters and generalized epidermolysis. Immune checkpoint inhibitors (ICIs), epidermal growth factor tyrosine kinase inhibitors (EGFR-TKIs), and multi-kinase inhibitors (MKIs) are three types of molucular therapy popularly used in advanced non-small cell lung cancer (NSCLC). The therapies can cause keratinocytes apoptosis, leading to SJS/TEN, which is not common but always life-threatening. We performed a retrospective analysis of case reports about ICIs, EGFR-TKIs, MKIs induced SJS/TEN by exploring PubMed, the Embase database, CNKI and WanFang. We analyzed 32 cases of SJS/TEN caused by ICIs (pembrolizumab, 11; nivolumab, 10; Ipilimumab + nivolumab, 5; Tislelizumab, 2; Toripalimab, 1; atezolizumab, 1; Camrelizumab, 1; Sintilimab+Toripalimab, 1). SJS/TEN could occur from 1 week to 5 months after initiation of ICIs, which was usually 1-2 cycles of treatment. SJS/TEN caused by ICIs is characterized by severe condition and high mortality. 11/32 patients were dead (pembrolizumab, 3; nivolumab, 3; Ipilimumab + nivolumab, 4; Sintilimab+Toripalimab, 1). Almost all patients who developed serious SJS/TEN had pre-symptoms, such as acneiform eruption, xerosis, pruritus. There were 8 cases of SJS/TEN associated with EGFR-TKIs (Osimertinib, 4; afatinib, 2; gefitinib, 1; vandetanib, 1). SJS/TEN usually occurred from 20 to 50 days of administration. The earliest occurrence time was 8 days, the latest occurrence was 78 days. There were 3 cases of MKIs related SJS/TEN (Regorafenib, 1; Sorafenib, 1; apatinib, 1). The apatinib-related case was treated with the combination of Toripalimab. No death associated with EGFR-TKIs and MKIs related SJS/TEN was reported. Compared with ICIS, EGFR-TKIs and MKIS related SJS/TEN is less common and mild, with well respond to steroid therapy and immunoglobulin and less deaths. It might be necessary to use anti-allergic agents before ICIs.