Acquired resistance mechanisms to osimertinib: The constant battle

Novel Approach to Overcome Osimertinib Resistance Using Bromodomain and Extra-Terminal Domain Inhibitors

Osimertinib, a third-generation EGFR-tyrosine kinase inhibitor, is the first-line therapy for lung cancer harboring EGFR mutations. The mechanisms underlying osimertinib resistance are diverse, with approximately half remaining unknown. Epigenetic dysregulation is implicated in drug resistance; however, the mechanisms remain unclear. Therefore, we investigated epigenetic involvement in osimertinib resistance and its therapeutic potential. We established osimertinib-resistant cells and used an assay for transposase-accessible chromatin using sequencing to evaluate chromatin accessibility, finding significant changes post-resistance. Combining the assay for transposase-accessible chromatin and RNA sequencing data, we identified FGF1 as a resistance-related gene regulated by histone modifications. FGF1 induced osimertinib resistance, and its suppression attenuated resistance. Bromodomain and extra-terminal domain inhibitors combined with osimertinib overcame osimertinib resistance by reducing FGF1 expression. Increased FGF1 expression was observed in osimertinib-resistant clinical samples. This combination therapy was effective in cell lines and mouse xenograft models. These results suggest targeting histone modifications using bromodomain and extra-terminal domain inhibitors as a novel approach to overcoming osimertinib resistance.

Liensinine overcomes EGFR-TKI resistance in lung adenocarcinoma through DRP1-mediated autophagy

INTRODUCTION

Persistent upregulation of autophagy contributes to tumour cells' resistance to EGFR-TKI therapy, and hence, inhibiting autophagy could be a valuable strategy for overcoming such resistance.

OBJECTIVES

This study investigated the effects of liensinine in EGFR-TKI resistant lung adenocarcinoma (LUAD) and to explore the underlying mechanism.

METHODS

CCK-8 assay, colony formation, EdU assay and apoptosis assays were conducted for investigating the effect of EGFR-TKI and liensinine combination treatment in LUAD. Furthermore, autophagic flux were detected by western blot, fluorescence assays and TEM. In addition, by employing a DARTS approach, a CETSA assay, and SPR analysis, we identified DRP1 as a target of liensinine. Finally, by establishing a xenograft model of the disease, the impact of combination treatment in vivo was assessed.

RESULT

In vitro and in vivo experiments revealed that the novel autophagy inhibitor liensinine enhanced the sensitivity of LUAD to EGFR-TKIs. This effect was achieved by inhibiting autophagic flux. We then examined whether liensinine inhibits autophagic flux through the impairment of autophagosome and autolysosome degradation. Furthermore, we identified DRP1 as a target of liensinine. The activation of DRP1 by liensinine through dephosphorylation at Ser637 promotes the accumulation of autophagosomes and autolysosomes while simultaneously blocking autophagic flux, thereby enhancing the cancer cell-killing effects of EGFR-TKIs.

CONCLUSIONS

Our study validated the efficacy of liensinine in overcoming EGFR-TKI resistance and elucidated the mechanism underlying liensinine's inhibition of autophagy.

Non-Small Cell Lung Cancer with Epidermal Growth Factor Receptor (EGFR) Common Mutations: New Strategies

Epidermal growth factor receptor (EGFR) mutations are described in 10-15% of Caucasian patients and in 50% of Asian patients with non-squamous non-small cell lung cancer (NSCLC). The introduction of tyrosine kinase inhibitors (TKIs) has revolutionized the therapeutic scenario and has changed the natural history of the disease. Despite the results obtained with osimertinib, a third-generation TKI, most patients experience disease progression. The search for new therapeutic strategies both to enhance first-line treatment and to ensure adequate second-line therapies represents an unmet medical need, towards which all efforts are being concentrated. In this review, we describe the main strategies identified to improve the prognosis of patients with EGFR-mutated NSCLC.

Induction of IL6/STAT3-dependent TRAIL expression that contributes to the therapeutic efficacy of osimertinib in EGFR mutant NSCLC cells

The third-generation mutation-selective EGFR tyrosine kinase inhibitor (EGFR-TKI) osimertinib (or AZD9291) effectively induces apoptosis in EGFR mutant (EGFRm) non-small cell lung cancer (NCSLC) cells. However, the underlying mechanisms have not been fully elucidated. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL or TNFSF10) is known as a death ligand that initiates apoptosis via binding to its cell surface death receptors such as DR5. In this study, we found that osimertinib and other EGFR-TKIs increased the expression of TRAIL primarily in EGFRm NSCLC cell lines. This effect was accompanied with increased IL6 expression and STAT3 activation. Inhibition of STAT3 with either protein degradation or gene knockout abrogated the ability of osimertinib or recombinant human IL6 to elevate TRAIL levels. Moreover, osimertinib increased STAT3-dependent transcription of TRAIL via two STAT3 novel binding sites present in the TRAIL 5'flanking region. Hence, osimertinib induces IL6/STAT3-mediated TRAIL expression in EGFRm NSCLC cells. While osimertinib lost the ability to induce TRAIL expression in osimertinib-resistant EGFRm NSCLC, knockdown or knockout of TRAIL in sensitive EGFRm NSCLC cells rendered them less sensitive to osimertinib both in vitro and in vivo. Thus, TRAIL elevation contributes to the induction of apoptosis by osimertinib in EGFRm NSCLC cells. Furthermore, osimertinib increased membrane-bound TRAIL and DR5 membrane clustering and DR5 knockdown significantly compromised the cell-killing effect of osimertinib, together suggesting a DR5-dependent effect. Collectively, this study has revealed a previously undiscovered connection between TRAIL induction and osimertinib-induced apoptosis in EGFRm NSCLC cells, increasing our understanding of mechanisms accounting for apoptosis induced by osimertinib.

Receptor Tyrosine Kinase Fusion-Mediated Resistance to EGFR TKI in EGFR-Mutant NSCLC: A Multi-Center Analysis and Literature Review

INTRODUCTION

Drug resistance remains a major clinical challenge in EGFR-mutant NSCLC tumors owing to pathway reactivation, pathway bypass, and pathway indifference resistance mechanisms to evade tyrosine kinase inhibitor (TKI) suppression. Fusion of receptor tyrosine kinases (RTKs), such as RET, ALK, and FGFR3, has been reported to mediate EGFR TKI resistance. Given the rarity of these fusions and the heterogeneous nature of the condition, no prospective clinical trials evaluated the incidence, safety, and therapeutic benefit of dual EGFR-RTK inhibition.

METHODS

We queried clinical databases from multiple institutions to identify patients who had RTK fusions detected on next-generation sequencing testing results from tissue or blood at five institutions: the Second Affiliated Hospital Zhejiang University School of Medicine, Hunan Cancer Hospital, Prince of Wales Hospital Chinese University of Hong Kong, Chao Family Cancer Center, and the University of Texas MD Anderson Cancer Center from March 1, 2016, to September 30, 2023. The data analyzed included objective response rate (ORR) to treatment post RTK fusion detection, duration of treatment, and safety. A comprehensive literature search was conducted to identify patients with RTK fusion as the primary resistance mechanism in EGFR-mutated NSCLC patients.

RESULTS

Twenty-seven patients were identified to be eligible in the analysis. ALK fusions were most reported (42.9%), followed by RET fusions (35.7%). Fifteen patients received dual TKI after fusion detection and nine received fusion targeting single TKIs. The median time on treatment was 169 days or 5.8 months (35-1050 d). ORR by the Response Evaluation Criteria in Solid Tumors in the evaluable 25 patients was 24% and the disease control rate was 80%. In 14 evaluable patients who received dual TKI therapy, ORR by the Response Evaluation Criteria in Solid Tumors was 21.4%, and the disease control rate was 78.6%. No new toxicities were observed with dual EGFR-RTK inhibition. In the literature review, after pooling 291 patients from 59 studies, RET fusions were the most common (50.0%), followed by BRAF (13.3%), ALK (13.3%), FGFR (10%), NTRK (5.3%), EGFR (1.7%), ROS1 (1.3%), MET (1%), and ERBB (0.7%).

CONCLUSION

The emergence of RTK fusions is one of the mechanisms of bypass resistance of EGFR TKI. Dual inhibition of EGFR-RTK was safe and efficacious in patients with targetable RTK fusion after progression to EGFR TKIs.

Multieffect Specific Nanovesicles for Homing Resistant Tumors and Overcoming Osimertinib-Acquired Resistance in NSCLC

Acquired resistance to osimertinib (Osi) remains a major obstacle in the treatment of patients with EGFR-mutant non-small cell lung cancer (NSCLC). AXL elevation is a known key mechanism of Osi-resistance, and therapeutic strategies remain scarce. Emerging evidence reveals that an increased intracellular glutathione (GSH) level induces Osi resistance. In this study, a new mechanism is identified by which GSH regulates AXL expression via glutathione peroxidase 4 (GPX4) in Osi-resistant cells. A multifunctional covalent organic framework (COF) nanoplatform for GSH consumption, AXL inhibition, and co-delivery of the AXL inhibitor (Brigatinib) and Osi is creatively constructed to confirm whether Osi sensitivity improves by simultaneously targeting GSH-AXL resistance mechanisms. Furthermore, it is coated, for the first time, the COF carrier system with specific vesicles to precisely home it into resistant tumors, where CDH2 adhesion molecules play a crucial role. The engineered multifunctional antiresistance-specific nanovesicles effectively inhibited the GSH-AXL axis, induced apoptosis in Osi-resistant cells both in vitro and in vivo, and delayed the progression of Osi-resistant tumors. Overall, these findings provide a novel strategy to overcome the Osi-acquired resistance caused by high AXL levels in NSCLC.

Ivacaftor, a CFTR potentiator, synergizes with osimertinib against acquired resistance to osimertinib in NSCLC by regulating CFTR-PTEN-AKT axis

Osimertinib, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), has demonstrated significant clinical benefits in the treatment of EGFR-mutated non-small cell lung cancer (NSCLC). However, inevitable acquired resistance to osimertinib limits its clinical utility, and there is a lack of effective countermeasures. Here, we established osimertinib-resistant cell lines and performed drug library screening. This screening identified ivacaftor, a cystic fibrosis transmembrane conductance regulator (CFTR) potentiator, as a synergistic enhancer of osimertinib-induced anti-tumor activity both in vitro and in vivo. Mechanistically, ivacaftor facilitated the colocalization of CFTR and PTEN on the plasma membrane to promote the function of PTEN, subsequently inhibiting the PI3K/AKT signaling pathway and suppressing tumor growth. In summary, our study suggests that activating CFTR enhances osimertinib-induced anti-tumor activity by regulating the PTEN-AKT axis. Furthermore, ivacaftor and osimertinib constitute a potential combination strategy for treating osimertinib-resistant EGFR-mutated NSCLC patients.

Network pharmacology and experimental analysis reveal Ethyl caffeate delays osimertinib resistance in lung cancer by suppression of MET

BACKGROUND

Fei Yanning Formula (FYN) is extensively applied in clinical lung cancer treatment. However, the specific active constituents and targets of its therapeutic effects remain unclear.

OBJECTIVE

The study aims to explore the active constituents and mechanism of FYN in delaying osimertinib resistance by network pharmacology analysis and experimental verification.

METHODS

We collected the chemical constituents of the FYN based on the TCMSP database and relevant literature sources. Osimertinib resistance-related targets were acquired from the GeneCards database. We systematically construct the PPI network and KEGG analysis to explore hub targets and key pathways. The main active components of FYN were identified by molecular docking. Subsequently, we conducted in vitro experiments to verify its effect on osimertinib-resistant cells in lung cancer.

RESULTS

The PPI network and KEGG pathways analysis revealed six key targets linked to PI3K-AKT signaling pathways (ERBB2, EGFR, MET, HSP90AA1, MCL1, and IGF1R). RT-qPCR and immunohistochemical analyses demonstrated that FYN could suppress the expression of ERBB2, MET and HSP90AA1. Molecular docking indicated that Ethyl caffeate, the primary component in FYN, had a stronger binding ability with MET. Experiments illustrated that Ethyl caffeate inhibited the migration and proliferation of osimertinib-resistant cells, promoted apoptosis, and suppressed the expression level of MET.

CONCLUSION

FYN might delay osimertinib resistance by downregulating the expression of MET, which can be attributed to its active ingredient, Ethyl caffeate.

Aumolertinib plus chemotherapy as first-line treatment for advanced NSCLC with EGFR exon 19 deletion or exon 21 L858R: a phase II trial

BACKGROUND

To evaluate the efficacy and safety of aumolertinib combined with pemetrexed and carboplatin as first-line treatment in advanced non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation (exon 19 deletion or exon 21 L858R).

METHODS

In phase II trial (NCT04646824), patients received aumolertinib 110 mg once daily plus pemetrexed (500 mg/m2) and carboplatin (area under curve = 5) once every 3 weeks for 4 cycles, followed by maintenance aumolertinib (110 mg once daily) and pemetrexed (500 mg/m2 once every 4 weeks). The primary endpoint was progression-free survival (PFS). Secondary endpoints included objective response rate (ORR), disease control rate (DCR), overall survival (OS), and safety.

RESULTS

From November 2020 to October 2021, 34 patients were included for analysis. The median PFS was 28.0 months (95% CI, 18.7-36.9). The ORR was 91.2% (31/34), and the DCR was 100%. The median OS was not reached. Of 28 patients with circulating tumor DNA (ctDNA) testing, 22 (78.6%) showed clearance of EGFR mutation after 2 or 4 cycles. The median PFS was 31 months in patients with EGFR mutation clearance in ctDNA, and the ORR of them was higher than those without EGFR mutation clearance in ctDNA (90.9% vs 33.3%). The most common grade ≥ 3 treatment-related adverse event was decreased neutrophil count (22 [64.7%]).

CONCLUSION

Aumolertinib plus chemotherapy shows potential as first-line treatment for patients with EGFR-mutant advanced NSCLC, which deserves to be investigated in randomized controlled trials. CtDNA clearance may be a prognostic marker.

Epigenetic code underlying EGFR-TKI resistance in non-small cell lung cancer: Elucidation of mechanisms and perspectives on therapeutic strategies

Non-small-cell lung cancer (NSCLC) is the most common lung cancer subtype, and epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are the core drugs used for its treatment. However, the emergence of drug resistance poses a significant challenge to their clinical efficacy. As a significant role-player in cancer development and maintenance, histone modifications, DNA methylation and noncoding RNA (ncRNA) changes have been proven to play a crucial part in driving EGFR-TKI resistance, which provides promising potential therapeutic targets and biomarkers for overcoming drug resistance. This review delves into the complex epigenetic mechanisms that cause EGFR-TKI resistance and emphasizes the potential of combined epigenetic therapies, aiming to provide better-targeted treatment options for NSCLC patients with NSCLC and drive innovative strategies to overcome the challenges of drug resistance.

Single-Cell RNA Sequencing in Unraveling Acquired Resistance to EGFR-TKIs in Non-Small Cell Lung Cancer: New Perspectives

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have demonstrated remarkable efficacy in treating non-small cell lung cancer (NSCLC), but acquired resistance greatly reduces efficacy and poses a significant challenge to patients. While numerous studies have investigated the mechanisms underlying EGFR-TKI resistance, its complexity and diversity make the existing understanding still incomplete. Traditional approaches frequently struggle to adequately reveal the process of drug resistance development through mean value analysis at the overall cellular level. In recent years, the rapid development of single-cell RNA sequencing technology has introduced a transformative method for analyzing gene expression changes within tumor cells at a single-cell resolution. It not only deepens our understanding of the tumor microenvironment and cellular heterogeneity associated with EGFR-TKI resistance but also identifies potential biomarkers of resistance. In this review, we highlight the critical role of single-cell RNA sequencing in lung cancer research, with a particular focus on its application to exploring the mechanisms of EGFR-TKI-acquired resistance in NSCLC. We emphasize its potential for elucidating the complexity of drug resistance mechanism and its promise in informing more precise and personalized treatment strategies. Ultimately, this approach aims to advance NSCLC treatment toward a new era of precision medicine.

A new fluorescent oxaliplatin(iv) complex with EGFR-inhibiting properties for the treatment of drug-resistant cancer cells

Platinum chemotherapy is part of every second anticancer treatment regimen. However, its application is limited by severe side effects and drug resistance. The combination of platinum-based chemotherapeutics with EGFR inhibitors has shown remarkable synergism in clinical treatment. To enhance the tolerability of this combination, we designed a novel multi-action oxaliplatin-based platinum(iv) complex with an EGFR-inhibiting moiety (KP2749). KP2749 releases two independent cytotoxic agents upon reduction: oxaliplatin and the EGFR inhibitor KP2187, which was selected for its strong intrinsic fluorescence that became quenched upon complexation to metal ions. In particular, KP2749 demonstrated high stability and specific KP2187 release, with quenched fluorescent properties in its intact form, facilitating the investigation of its intracellular reduction. Notably, by exploiting its fluorescence, we demonstrated that intact KP2749 itself exhibited EGFR-inhibitory properties. Furthermore, subsequent experiments indicated that our complex was able to overcome resistance to oxaliplatin and EGFR inhibitors in vitro and in xenograft models in vivo. These effects were not only based on EGFR inhibition and DNA damage, but also improved cellular drug uptake. Finally, in silico docking analysis confirmed that the intact KP2749 complex had EGFR-binding properties, which were different from free KP2187. Consequently, these data suggested that the coordination of EGFR inhibitors to metal cores (like platinum) allow the fine-tuning of their EGFR-targeting properties. In conclusion, this study not only presents a new potential anticancer drug but also offers a novel fluorescent tool to study the intracellular drug release kinetics of platinum(iv) complexes.

Itraconazole Reversing Acquired Resistance to Osimertinib in NSCLC by Inhibiting the SHH/DUSP13B/p-STAT3 Axis

There is an urgent necessity to devise efficient tactics to tackle the inevitable development of resistance to osimertinib, which is a third-generation epidermal growth factor receptor (EGFR) inhibitor used in treating EGFR-mutant nonsmall cell lung cancer (NSCLC). This study demonstrates that combining itraconazole with osimertinib synergistically reduces the proliferation and migration, enhances the apoptosis of osimertinib-resistant cells, and effectively inhibits the growth of osimertinib-resistant tumors. Mechanistically, itraconazole combined with osimertinib promotes the proteasomal degradation of sonic hedgehog (SHH), resulting in inactivation of the SHH/Dual-specificity phosphatase 13B (DUSP13B)/p-STAT3 and Hedgehog pathways, suppressing Myc proto-oncogene protein (c-Myc). Additionally, DUSP13B interacts with signal transducer and activator of transcription 3 (STAT3) and modulates its phosphorylation. Interestingly, it is observed that SHH overexpression partially rescues the synergistic effects of this combination treatment strategy through the SHH/DUSP13B/p-STAT3 signaling axis. Moreover, it is found that SHH, (GLI1), p-STAT3, and DUSP13B play significant predictive roles in osimertinib resistance. In lung adenocarcinoma, p-STAT3 is positively correlated with SHH but negatively correlated with DUSP13B. Together, these results highlight the crucial role of itraconazole in reversing the acquired resistance to osimertinib and provide a scientific rationale for the therapeutic strategy of combining osimertinib with itraconazole.

Rare transformation from lung adenocarcinoma to sarcomatoid carcinoma mediates resistance to inhibitors targeting different driver oncogenes

Background

Phenotypic transition is a common resistance mechanism of targeted therapy. While transformations from lung adenocarcinoma (LUAD) to small-cell lung cancer or squamous-cell carcinoma have been extensively studied, the conversion into sarcomatoid carcinoma (SC) is rarely reported.

Methods

Genetic and histological examinations were systematically performed on tumor re-biopsy samples obtained from patients with advanced EGFR-mutant LUAD who progressed on EGFR-tyrosine kinase inhibitors (TKIs). EGFR wild-type patients were also identified who underwent the rare transformation from adenocarcinoma to SC following the ineffectiveness of inhibitors that target distinct driver oncogenes. Furthermore, we also retrospectively collected 42 cases diagnosed with primary pulmonary SC as a comparison cohort to comprehensively characterize the biological events and clinical outcomes of transformed SC.

Results

The sarcomatoid transformation mediated drug resistance in 2.5 % and 4.8 % of patients after failure on the first/second, and third-generation EGFR-TKIs. Transformation of sarcomatoid carcinoma is characterized by a higher frequency of TP53, RB1, and MET genetic alterations compared to cases lacking histological transformation; the PI3K signaling pathway was also significantly activated. Fifteen individuals were identified with a rare transition from adenocarcinoma to SC, consisting of seven cases with EGFR-activating mutations and eight cases without EGFR mutations. All sarcomatoid-transformed samples not only retained their original driver mutations but also shared specific genetic alterations with primary LUAD. Moreover, transformed sarcomatoid carcinomas mimic the primary SC in terms of immunochemical and molecular features.

Conclusions

The transformation from lung adenocarcinoma to SC is a resistance mechanism wildly applied to inhibitors targeting different driver oncogenes. Immunotherapy plus chemotherapy shows potential to benefit patients with sarcomatoid transformation and warrants further study in larger cohorts.

Clinical utility and predictive value of cerebrospinal fluid cell-free DNA profiling in non-small cell lung cancer patients with leptomeningeal metastasis

Leptomeningeal metastasis (LM) is a challenging complication of non-small cell lung cancer (NSCLC). Cerebrospinal fluid (CSF) cell-free DNA (cfDNA) analysis using next-generation sequencing (NGS) offers insights into resistance mechanisms and potential treatment strategies. We conducted a study from February 2022 to April 2023 involving patients from five hospitals in Taiwan who had recurrent or advanced NSCLC with LM. These patients underwent CSF cfDNA analysis using a 118-gene targeted panel for NGS, with comprehensive clinical data collected. Among 25 enrolled patients, 22 (88.0 %) had EGFR mutations, while three (12.0 %) had EML4-ALK fusion, KIF5B-RET fusion, and ERBB2 A775_G776insSVMA. CSF cfDNA sequencing of 27 samples (from 25 patients) all confirmed their original driver mutations. Of total cohort, 18 patients (72.0 %) underwent intrathecal pemetrexed (ITP), with a median survival time of 7.4 months (95.0 % confidence interval, 3.3-11.6) from the initiation of ITP to death. Among them, ten individuals (55.6 %) survived beyond 6 months. Notably, MET copy number gain (CNG) correlated significantly with survival time exceeding 6 months after ITP (p = 0.007). The coexistence of EGFR T790M and EGFR-independent resistance alterations was associated with shorter survival times after ITP, with a median survival time of 1.9 months compared to 9.9 months for those without EGFR T790M (p = 0.010). Our results highlight CSF cfDNA NGS's potential in LM resistance understanding and ITP efficacy prediction. MET CNG positively impacts survival for ITP recipients, whereas the coexistence of EGFR T790M and EGFR-independent resistance mechanisms leads to poor outcomes.

CCDC34 maintains stemness phenotype through β-catenin-mediated autophagy and promotes EGFR-TKI resistance in lung adenocarcinoma

Despite recent advances in treatment strategy, lung cancer remains the leading cause of cancer-related mortality worldwide, and it is a serious threat to human health. Lung adenocarcinoma (LUAD) is the most common histological type of lung cancer, and approximately 40-50% of patients with LUAD in Asian populations have epidermal growth factor receptor (EGFR) mutations. The use of EGFR tyrosine kinase inhibitors (EGFR-TKIs) has revolutionarily improved the prognosis of patients with EGFR-mutated LUAD. However, acquired drug resistance is the main cause of treatment failure. Therefore, new therapeutic strategies are necessary to address the resistance to EGFR-TKIs in patients with LUAD. Cancer stemness-related factors lead to multiple-drug resistance in cancer treatment, including EGFR-TKI resistance. Coiled-coil domain-containing 34 (CCDC34) serves as an oncogene in several types of cancer. However, the role and molecular mechanism of CCDC34 in the malignant progression of LUAD have not been reported to date. In the present study, we found that CCDC34 may be associated with LUAD stemness through weighted gene co-expression network analysis (WGCNA). Furthermore, we demonstrated that CCDC34 promoted LUAD stemness properties through β-catenin-mediated regulation of ATG5-induced autophagy, which was conducive to acquired EGFR-TKI resistance in LUAD in vitro and in vivo. Knockdown CCDC34 can synergistically inhibit tumor growth when combined with EGFR-TKIs. This study reveals a positive association between CCDC34 and the stemness phenotype of LUAD, providing new insights into overcoming EGFR-TKI resistance in LUAD by inhibiting CCDC34 expression.

Aberrant expression of MRAS and HEG1 as the biomarkers for osimertinib resistance in LUAD

Epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) are the most applied targeted therapy for EGFR-mutant lung adenocarcinoma (LUAD). The third-generation EGFR-TKI, osimertinib, is widely used throughout lung cancer treatment, with single or combination modes. One of the main barriers in osimertinib treatment is the acquired resistance and mechanisms are not fully understood. Gene expression other than genetic mutations might predict drug response and mediate resistance occurrence. We analyzed six datasets of osimertinib-resistant LUAD cells from the Gene Expression Omnibus (GEO) database and identified two hub genes, named MRAS and HEG1. We found that the expression mode of MRAS/HEG1 in LUAD was osimertinib-dependent and contributed to drug resistance. We also explored potential mechanisms of hub genes related osimertinib resistance and emphasized the M2 infiltration involved. Moreover, potential therapeutic agents conquering MRAS/HEG1-related resistance were also identified. In conclusion, MRAS and HEG1 might be responsible for osimertinib resistance and could be promising prognostic biomarkers for osimertinib response in LUAD, which might provide insights into therapeutic strategies.

Comprehensive review of LncRNA-mediated therapeutic resistance in non-small cell lung cancer

Long non-coding RNAs (lncRNAs) are emerging as crucial regulators of gene expression through diverse mechanisms, including regulation of protein localization, sequestration of miRNAs, recruitment of chromatin modifiers, and modulation of signaling pathways. Accumulating evidence highlights their pivotal roles in tumor initiation, progression, and the development of therapeutic resistance. In this review, we comprehensively summarized the existing literature to identify lncRNAs associated with treatment responses in non-small cell lung cancer (NSCLC). Specifically, we categorized these lncRNAs based on their mechanisms of action in mediating resistance to chemotherapy, targeted therapy, and radiotherapy. Our analysis revealed that aberrant expression of various lncRNAs contributes to the development, metastasis, and therapeutic resistance in NSCLC, ultimately leading to poor clinical outcomes. By elucidating the intricate mechanisms through which lncRNAs modulate therapeutic responses, this review aims to provide mechanistic insights into the heterogeneous treatment outcomes observed in NSCLC patients and unveil potential therapeutic targets for overcoming drug resistance.

Inhibition of hTERT/telomerase/telomere mediates therapeutic efficacy of osimertinib in EGFR mutant lung cancer

The inevitable acquired resistance to osimertinib (AZD9291), an FDA-approved third-generation EGFR tyrosine kinase inhibitor (EGFR-TKI) for the treatment of patients with advanced non-small cell lung cancer (NSCLC) harboring EGFR activating or T790M resistant mutations, limits its long-term clinical benefit. Telomere maintenance via telomerase reactivation is linked to uncontrolled cell growth and is a cancer hallmark and an attractive cancer therapeutic target. Our effort toward understanding the action mechanisms, including resistance mechanisms, of osimertinib has led to the identification of a novel and critical role in maintaining c-Myc-dependent downregulation of hTERT, a catalytic subunit of telomerase, and subsequent inhibition of telomerase/telomere and induction of telomere dysfunction in mediating therapeutic efficacy of osimertinib. Consequently, osimertinib combined with the telomere inhibitor, 6-Thio-dG, which is currently tested in a phase II trial, effectively inhibited the growth of osimertinib-resistant tumors, regressed EGFRm NSCLC patient-derived xenografts, and delayed the emergence of acquired resistance to osimertinib, warranting clinical validation of this strategy to manage osimertinib acquired resistance.

Preparation and antitumor activity of selenium nanocomposite stabilized by AAGL from Agerocybe aegerita

Selenium nanoparticles (SeNPs) have limited bioavailability because of their poor stability in aqueous solutions. AAGL, a naturally active protein, extracted from Agrocybe aegerita has strong antitumor activity. However, whether AAGL can been used to stabilize SeNPs, and exerts anti-lung cancer effects remains unknown. In this study, a novel nanocomposite, AAGL-SeNPs, was prepared using AAGL-encapsulated SeNPs. The particle size of the AAGL-SeNPs was approximately 206.1 nm, which was uniform and well dispersed in aqueous solution and showed satisfactory stability. AAGL-SeNPs was non-toxic and reduced the hepatotoxicity of AAGL in mice. Importantly, AAGL-SeNPs inhibited the proliferation of lung cancer cells and suppressed tumor growth in tumor-bearing mice. AAGL-SeNPs enhanced the cytotoxic effects on lung cancer cells by stimulating immune cells. In addition, the combination of AAGL-SeNPs and osimertinib inhibited lung cancer, and AAGL-SeNPs reversed osimertinib resistance in H1975 cells. Mechanistically, Krüppel-like transcriptional factor 4 (KLF4) was identified by data-independent acquisition mass spectrometry (DIA-MS), and its expression levels in lung cancer increased after AAGL-SeNPs treatment. This study demonstrated that nanocomposite AAGL-SeNPs is stable, safe, and has excellent antitumor efficacy, which will be a potential therapeutic drug for lung cancer treatment.

Xanthohumol overcomes osimertinib resistance via governing ubiquitination-modulated Ets-1 turnover

Non-small cell lung cancer (NSCLC) is a prevalent and fatal malignancy with a significant global impact. Recent advancements have introduced targeted therapies like tyrosine kinase inhibitors (TKIs) such as osimertinib, which have improved patient outcomes, particularly in those with EGFR mutations. Despite these advancements, acquired resistance to TKIs remains a significant challenge. Hence, one of the current research priorities is understanding the resistance mechanisms and identifying new therapeutic targets to improve therapeutic efficacy. Herein, we identified high expression of c-Met in osimertinib-resistant NSCLC cells, and depletion of c-Met significantly inhibited the proliferation of osimertinib-resistant cells and prolonged survival in mice, suggesting c-Met as an attractive therapeutic target. To identify effective anti-tumor agents targeting c-Met, we screened a compound library containing 641 natural products and found that only xanthohumol exhibited potent inhibitory effects against osimertinib-resistant NSCLC cells. Moreover, combination treatment with xanthohumol and osimertinib sensitized osimertinib-resistant NSCLC cells to osimertinib both in vitro and in vivo. Mechanistically, xanthohumol disrupted the interaction between USP9X and Ets-1, and inhibited the phosphorylation of Ets-1 at Thr38, promoting its degradation, thereby targeting the Ets-1/c-Met signaling axis and inducing intrinsic apoptosis in osimertinib-resistant NSCLC cells. Overall, the research highlights the critical role of targeting c-Met to address osimertinib resistance in NSCLC. By demonstrating the efficacy of xanthohumol in overcoming resistance and enhancing therapeutic outcomes, this study provides valuable insights and potential new strategies for improving the clinical management of NSCLC.

The potential role of next-generation sequencing in identifying MET amplification and disclosing resistance mechanisms in NSCLC patients with osimertinib resistance

Purposes

Osimertinib, one of the third-generation EGFR-tyrosine kinase inhibitors (TKIs) designed to target EGFR T790M mutation, significantly improves the prognosis of lung cancer. However, drug resistance still happens and MET amplification is responsible for one of the main causes. Fluorescence in situ hybridization (FISH) is the gold standard for MET amplification detection, but fundamentally limited by observer subjectivity. Herein, we assessed the value of next-generation sequencing (NGS) method in MET amplification detection in non-small cell lung cancer (NSCLC), as well as revealed the mutation profiling of NSCLC patients with osimertinib resistance to provide some valuable clues to the mechanisms of resistance.

Methods

A total of 317 cancer tissue samples from 317 NSCLC patients at time of progression following osimertinib were submitted to NGS and only 96 tissues were tested by FISH simultaneously. With FISH results as gold standard, enumeration algorithm was applied to establish the optimal model for identifying MET amplification using gene copy number (GCN) data.

Results

The optimal model for identifying MET amplification was constructed based on the GCN of MET, BRAF, CDK6 and CYP3A4, which achieved a 74.0% overall agreement with FISH and performed well in identifying MET amplification except polysomy with a sensitivity of 85.7% and a specificity of 93.9%. The inconsistency between NGS and FISH occurred mainly in polysomy subtype, while MET GCN ≥ 5 could be reliably recognized by NGS. Moreover, the most frequently mutated genes in NSCLC patients with osimertinib resistance were EGFR (59.94%), followed by TP53 (43.85%), NRG1 (9.46%), PIK3CA (6.31%), and ATM (5.36%). The known resistance mechanisms, including MET amplification, EGFR (C797S, L718Q/R), TP53, CDK4, CDK6, CDKN2A, BRAF, KRAS, NRAS and PIK3CA mutations were also disclosed in our cohort.

Conclusions

NGS assay can achieve a high concordance with FISH in MET amplification detection and has advantages in portraying various genetic alterations, which is of worthy in clinical promotion.

Strategies for enhancing non-small cell lung cancer treatment: Integrating Chinese herbal medicines with epidermal growth factor receptor-tyrosine kinase inhibitors therapy

Non-small cell lung cancer (NSCLC) poses a global health threat, and epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) such as gefitinib, afatinib, and osimertinib have achieved significant success in clinical treatment. However, the emergence of resistance limits the long-term efficacy of these treatments, necessitating urgent exploration of novel EGFR-TKIs. This review provides an in-depth summary and exploration of the resistance mechanisms associated with EGFR-TKIs, with a specific focus on representative drugs like gefitinib, afatinib, and osimertinib. Additionally, the review introduces a therapeutic strategy involving the combination of Chinese herbal medicines (CHMs) and chemotherapy drugs, highlighting the potential role of CHMs in overcoming NSCLC resistance. Through systematic analysis, we elucidate the primary resistance mechanisms of EGFR-TKIs in NSCLC treatment, emphasizing CHMs as potential treatment medicines and providing a fresh perspective for the development of next-generation EGFR-TKIs. This comprehensive review aims to guide the application of CHMs in combination therapy for NSCLC management, fostering the development of more effective and comprehensive treatment modalities to ultimately enhance patient outcomes.

The combined inhibition of SLC1A3 and glutaminase in osimertinib-resistant EGFR mutant cells

BACKGROUND

We investigated the unknown mechanisms of osimertinib-resistant EGFR-mutant lung cancer.

METHODS

An osimertinib-resistant cell line (PC-9/OsmR2) was established through continuous exposure to osimertinib using an EGFR exon 19 deletion (19Del) lung adenocarcinoma cell line (PC-9). EGFR 19Del (M1), L858R/T790M/C797S (M6), and L858R/C797S (M8) expression vectors were introduced into Ba/F3 cells. A second osimertinib-resistant line (M1/OsmR) was established through continuous exposure to osimertinib using M1 cells.

RESULTS

SLC1A3 had the highest mRNA expression level in PC-9/OsmR2 compared to PC-9 cells by microarray analysis and SLC1A3 was increased by flow cytometry. In PC-9/OsmR2 cells, osimertinib sensitivity was significantly increased in combination with siSLC1A3. Because SLC1A3 functions in glutamic acid transport, osimertinib with a glutaminase inhibitor (CB-839) or an SLC1A3 inhibitor (TFB-TBOA) increased the sensitivity. Also, CB-839 plus TFB-TBOA without osimertinib resulted in greater susceptibility than did CB-839 or TFB-TBOA plus osimertinib. Comprehensive metabolome analysis showed that the M1/OsmR cells had significantly more glutamine and glutamic acid than M1 cells. CB-839 plus osimertinib exerted a synergistic effect on M6 cells and an additive effect on M8 cells.

CONCLUSION

Targeting glutaminase and glutamic acid may overcome the osimertinib-resistant EGFR-mutant lung cancer.

Dual-target inhibitors of colchicine binding site for cancer treatment

Colchicine binding site inhibitors (CBSIs) have attracted much attention due to their antitumor efficacies and the advantages of inhibiting angiogenesis and overcoming multidrug resistance. However, no CBSI has been currently approved for cancer treatment due to the insufficient efficacies, serious toxicities and poor pharmacokinetic properties. Design of dual-target inhibitors is becoming a potential strategy for cancer treatment to improve anticancer efficacy, decrease adverse events and overcome drug resistance. Therefore, we reviewed dual-target inhibitors of colchicine binding site (CBS), summarized the design strategies and the biological activities of these dual-target inhibitors, expecting to provide inspiration for developing novel dual inhibitors based on CBS.

Cancer-associated fibroblast-derived colony-stimulating factor 2 confers acquired osimertinib resistance in lung adenocarcinoma via promoting ribosome biosynthesis

Acquired resistance is a major obstacle to the therapeutic efficacy of osimertinib in lung adenocarcinoma (LUAD), but the underlying mechanisms are still not fully understood. Cancer-associated fibroblasts (CAFs) are the most abundant stromal cell type in LUAD tumor-microenvironment (TME) and have emerged as a key player in chemoresistance. However, the function of CAFs in osimertinib resistance is still unclear. Here, we showed that CAFs derived from osimertinib-resistant LUAD tissues (CAFOR) produced much more colony-stimulating factor 2 (CSF2) than those isolated from osimertinib-sensitive tissues. CAFOR-derived CSF2 activated the Janus kinase 2 (JAK2)/Signal transducer and activator of transcription 3 (STAT3) signaling pathway and upregulated lnc-CSRNP3 in LUAD cells. Lnc-CSRNP3 then promoted the expression of nearby gene CSRNP3 by recruiting chromodomain helicase DNA binding protein 9 (CHD9) and inhibited the phosphatase activity of the serine/threonine protein phosphatase 1 catalytic subunit α (PP1α), thereby induced osimertinib resistance by enhancing ribosome biogenesis. Collectively, our study reveals a critical role for CAFs in the development of osimertinib resistance and identifies the CSF2 pathway as an attractive target for monitoring osimertinib efficacy and overcoming osimertinib resistance in LUAD.

Prognostic impact of Interleukin-8 levels in lung cancer: A meta-analysis and a bioinformatic validation

BACKGROUND

High interleukin-8 (IL-8) levels have been linked to poor prognosis in lung cancer, but conclusive data are lacking.

MATERIALS AND METHODS

A comprehensive search was conducted on April 1st, 2023, from electronic databases, focusing on studies with IL-8 expression evaluations and the availability of hazard ratio (HR) and 95% confidence intervals (CI) for overall survival (OS), progression-free survival (PFS) and disease-free survival (DFS) or adequate data for their estimation. Then, we examined IL-8 and CXCR1 RNA-seq data from The Cancer Genome Atlas (TCGA) dataset, and we correlated these data with OS.

RESULTS

Among 2655 produced records, 10 manuscripts involving both non-small cell lung cancer and small cell lung cancer, were included in the analysis. Two manuscripts and one study included two and three different cohorts, respectively, for a total of 14 cohorts of patients. Overall, 4 cohorts evaluated IL-8 levels in patients treated with chemotherapy, 3 cohorts immunotherapy, 2 cohorts surgical patients and 4 cohorts other treatments; 1 cohort was removed, as the type of treatments was lacking. The 12 cohorts included in the OS analysis revealed that patients with high IL-8 levels have a lower OS probability, as compared to patients with low IL-8 levels (HR=1.75, 95 % CI 1.36-2.26). No significant difference between patients with high and low IL-8 levels was observed in the 8 cohorts available for PFS analysis. Sensitivity analysis according to treatment revealed significant PFS and OS differences for patients treated with chemotherapy or immunotherapy. Analysis of RNA-seq data from TCGA, confirmed the correlation between high IL-8 and CXCR1 expression and worse OS in patients with resected lung cancer.

CONCLUSION

To the best of our knowledge, this study represents the first meta-analysis demonstrating a negative prognostic impact of high IL-8 level in lung cancer, particularly in patients treated with chemotherapy and/or immunotherapy.

Exploring the structural activity relationship of the Osimertinib: A covalent inhibitor of double mutant EGFRL858R/T790M tyrosine kinase for the treatment of Non-Small Cell Lung Cancer (NSCLC)

The USFDA granted regular approval to Osimertinib (AZD9291) on March 2017, for treating individuals with metastatic Non-Small Cell Lung Cancer having EGFR T790M mutation. Clinically, Osimertinib stands at the forefront for the treatment of patients with Non-Small Cell Lung Cancer. Osimertinib forms a covalent bond with the Cys797 residue and predominantly spares binding to WT-EGFR, thereby reducing toxicity and enabling the administration of doses that effectively inhibit T790M. However, a high percentage of patients treated with Osimertinib (AZD9291) developed a tertiary cysteine797 to serine797 (C797S) mutation in the EGFR kinase domain, rendering resistance to it. This comprehensive review sheds light on the chemistry, computational aspects, structural features, and expansive spectrum of biological activities of Osimertinib and its analogues. The in-depth exploration of these facets serves as a valuable resource for medicinal chemists, empowering them to design better Osimertinib analogues. This exhaustive study not only provides insights into improving potency but also emphasizes considerations for mutant selectivity and optimizing pharmacokinetic properties. This review acts as a guiding beacon for the strategic design and development of next-generation Osimertinib analogues.

A Visual Analysis of the Research Dynamics in Resistance to EGFR Inhibitors for NSCLC

Purpose

Activating mutations in epidermal growth factor receptor (EGFR) have been identified as key predictive biomarkers for the customized treatment with EGFR tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC), aiding in improving patient response rates and survival. However, resistance challenges the efficacy of these treatments, with limited understanding of post-resistance therapeutic strategies. A deep understanding of the biology and resistance mechanisms of EGFR-mutant NSCLC is crucial for developing new treatment approaches. This study, through bibliometric analysis, summarizes the trends in research on resistance to EGFR-TKIs.

Methods

Research papers on NSCLC with EGFR inhibitor resistance were collected from the Web of Science Core Collection (WoSCC). The analysis utilized bibliometric tools like CiteSpace, VOSviewer, and other platforms for comprehensive analysis and visualization of the outcomes.

Results

The WoSCC database contains a total of 5866 documents on resistance to EGFR-TKIs treatment, including 4727 articles (93.48%) and 1139 reviews (6.52%), spanning 81 countries and regions, 4792 institutions, with the involvement of 23,594 authors. Since 2016, there has been a significant increase in publications in this field. China has the highest publication output, while the United States has the highest citation count for papers. Harvard University leads in terms of the number of publications. Among the top ten journals with the highest output, Clinical Cancer Research has the highest impact factor at 11.5, with 90% of the journals classified in Q1 or Q2. Rafael Rosell is one of the most influential authors in this field, ranking second in publication volume and fourth in citation count. Research on EGFR-TKIs resistance mainly focuses on genetic testing, resistance mechanisms, and post-resistance treatment strategies.

Conclusion

This study provides researchers with a reliable basis and guidance for finding authoritative references, understanding research trends, and exploring potential directions.

BDTX-189, a novel tyrosine kinase inhibitor, inhibits cell activity via ERK and AKT pathways in the EGFR C797S triple mutant cells

The tertiary mutation C797S in the structural domain of the EGFR kinase is a common cause of resistance to third-generation EGFR tyrosine kinase inhibitors (TKIs). In this study, we used a potent, selective and irreversible inhibitor, BDTX-189, to target EGFR C797S triple mutant cells for cell activity. The study constructed the H1975-C797S (EGFR L858R/T790 M/C797S) cell line using the CRISPR/Cas9 method and investigated its potential as a fourth-generation tyrosine kinase inhibitor via chemosensitivity approach. The results demonstrated its ability to induce cytotoxic effects, and inhibit EGFR L858R/T790 M/C797S cell growth and proliferation in a dose-dependent manner. Meanwhile, BDTX-189 reduces the protein phosphorylation levels of EGFR, ERK, and AKT, promoting apoptosis. Furthermore, BDTX-189 not only inhibits common EGFR triple mutations but also effectively inhibits EGFR L858R mutation and EGFR L858R/T790 M mutation. These findings support the cytotoxic effect of BDTX-189 and its inhibitory effect on cell division and proliferation with the EGFR C797S triple mutation.

The Impact of Inadequate Exposure to Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitors on the Development of Resistance in Non-Small-Cell Lung Cancer Cells

Epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancer (NSCLC) patients treated with EGFR-tyrosine kinase inhibitors (TKIs) inevitably develop resistance through several biological mechanisms. However, little is known on the molecular mechanisms underlying acquired resistance to suboptimal EGFR-TKI doses, due to pharmacodynamics leading to inadequate drug exposure. To evaluate the effects of suboptimal EGFR-TKI exposure on resistance in NSCLC, we obtained HCC827 and PC9 cell lines resistant to suboptimal fixed and intermittent doses of gefitinib and compared them to cells exposed to higher doses of the drug. We analyzed the differences in terms of EGFR signaling activation and the expression of epithelial-mesenchymal transition (EMT) markers, whole transcriptomes byRNA sequencing, and cell motility. We observed that the exposure to low doses of gefitinib more frequently induced a partial EMT associated with an induced migratory ability, and an enhanced transcription of cancer stem cell markers, particularly in the HCC827 gefitinib-resistant cells. Finally, the HCC827 gefitinib-resistant cells showed increased secretion of the EMT inducer transforming growth factor (TGF)-β1, whose inhibition was able to partially restore gefitinib sensitivity. These data provide evidence that different levels of exposure to EGFR-TKIs in tumor masses might promote different mechanisms of acquired resistance.

The impact of EGFR T790M mutation status following the development of Osimertinib resistance on the efficacy of Osimertinib in non-small cell lung cancer: A meta-analysis

BACKGROUND

Previous studies have suggested that loss of the EGFR T790M gene mutation may contribute to the development of resistance to Osimertinib in non-small cell lung cancer (NSCLC).

AIMS

This study aims to assess the relationship between the clinical effectiveness of Osimertinib in NSCLC patients and the T790M mutation status following resistance to Osimertinib and examine differences between plasma and tissue tests and between Asian and non-Asian groups.

METHODS

The PubMed, Web of Science, Cochrane, and EMBASE databases were comprehensively searched for studies on the association between T790M mutation status and the efficacy of Osimertinib between January 2014 and November 2023. Meta-analysis was carried out using Review Manager 5.4 software.

RESULTS

After evaluating 2727 articles, a total of 14 studies were included in the final analysis. Positive correlations between EGFR T790M mutation status after Osimertinib resistance and longer PFS (HR: 0.44, 95% CI: 0.30-0.66), longer OS (HR: 0.3, 95% CI: 0.10-0.86), longer TTD (HR: 0.69, 95% CI: 0.45-1.07), and improved clinical outcomes including PFS and TTD subgroups (HR: 0.58, 95% CI: 0.47-0.73) were observed. Subgroup analysis revealed that, compared with the blood tests, the results of the T790M mutation tests by the tissue are more significant (HR: 0.24, 95% CI: 0.11-0.52 for tissue tests; HR: 0.47, 95% CI: 0.22-1.00 for plasma tests), and the PFS of Osimertinib were similar for Asian and non-Asian patients (HR: 0.46, 95% CI: 0.31-0.68 for Asians; HR: 0.12, 95% CI: 0.01-1.27 for non-Asians).

CONCLUSIONS

Persistence of the T790M gene mutation after the development of Osimertinib resistance is associated with higher therapeutic benefits of Osimertinib in NSCLC patients. The results of tissue detection are more significant than those of plasma detection.

DNA topoisomerase II inhibition potentiates osimertinib's therapeutic efficacy in EGFR-mutant non-small cell lung cancer models

Development of effective strategies to manage the inevitable acquired resistance to osimertinib, a third-generation EGFR inhibitor for the treatment of EGFR-mutant (EGFRm) non-small cell lung cancer (NSCLC), is urgently needed. This study reports that DNA topoisomerase II (Topo II) inhibitors, doxorubicin and etoposide, synergistically decreased cell survival, with enhanced induction of DNA damage and apoptosis in osimertinib-resistant cells; suppressed the growth of osimertinib-resistant tumors; and delayed the emergence of osimertinib-acquired resistance. Mechanistically, osimertinib decreased Topo IIα levels in EGFRm NSCLC cells by facilitating FBXW7-mediated proteasomal degradation, resulting in induction of DNA damage; these effects were lost in osimertinib-resistant cell lines that possess elevated levels of Topo IIα. Increased Topo IIα levels were also detected in the majority of tissue samples from patients with NSCLC after relapse from EGFR tyrosine kinase inhibitor treatment. Enforced expression of an ectopic TOP2A gene in sensitive EGFRm NSCLC cells conferred resistance to osimertinib, whereas knockdown of TOP2A in osimertinib-resistant cell lines restored their susceptibility to osimertinib-induced DNA damage and apoptosis. Together, these results reveal an essential role of Topo IIα inhibition in mediating the therapeutic efficacy of osimertinib against EGFRm NSCLC, providing scientific rationale for targeting Topo II to manage acquired resistance to osimertinib.

Pyrrolo[2,3-D]Pyrimidines as EGFR and VEGFR Kinase Inhibitors: A Comprehensive SAR Review

Tyrosine kinases are implicated in a wide array of cellular physiological processes, including cell signaling. The discovery of the BCR-ABL tyrosine kinase inhibitor imatinib and its FDA approval in 2001 paved the way for the development of small molecule chemical entities of diverse structural backgrounds as tyrosine kinase inhibitors for the treatment of various ailments. Two of the most prominent tyrosine kinases as drug targets are the epidermal growth factor receptor (EGFR) and the vascular endothelial growth factor receptor (VEGFR), as evidenced by the clinical success of their many inhibitors in the drug market. Among several other physiological roles, EGFR regulates epithelial tissue development and homeostasis, while VEGFR regulates tumor-induced angiogenesis. The pyrrolo[2,3-d]pyrimidine nucleus represents a deaza-isostere of adenine, the nitrogenous base of ATP. The recent introduction of many pyrrolo[2,3-d]pyrimidines to the drug market as tyrosine kinase inhibitors makes them a hot topic in the medicinal chemistry research area at the present time. This review article comprehensively sheds light on the structure-activity relationship (SAR) of pyrrolo[2,3-d]pyrimidines as EGFR and VEGFR tyrosine kinase inhibitors, aiming to provide help medicinal chemists in the design of future pyrrolopyrimidine kinase inhibitors.

The effect of PLK1 inhibitor in osimertinib resistant non-small cell lung carcinoma cells

OBJECTIVES

To investigate the effects of PLK1 inhibitors on osimertinib-resistant non-small cell lung carcinoma (NSCLC) cells and the anti-tumor effect combined with osimertinib.

METHODS

An osimertinib resistant NCI-H1975 cell line was induced by exposure to gradually increasing drug concentrations. Osimertinib-resistant cells were co-treated with compounds from classical tumor pathway inhibitor library and osimertinib to screen for compounds with synergistic effects with osimertinib. The Gene Set Enrichment Analysis (GSEA) was used to investigate the activated signaling pathways in osimertinib-resistant cells; sulforhodamine B (SRB) staining was used to investigate the effect of PLK1 inhibitors on osimertinib-resistant cells and the synergistic effect of PLK1 inhibitors combined with osimertinib.

RESULTS

Osimertinib-resistance in NCI-H1975 cell (resistance index=43.45) was successfully established. The PLK1 inhibitors GSK 461364 and BI 2536 had synergistic effect with osimertinib. Compared with osimertinib-sensitive cells, PLK1 regulatory pathway and cell cycle pathway were significantly activated in osimertinib-resistant cells. In NSCLC patients with epidermal growth factor receptor mutations treated with osimertinib, PLK1 mRNA levels were negatively correlated with progression free survival of patients (R=－0.62, P<0.05), indicating that excessive activation of PLK1 in NSCLC cells may cause cell resistant to osimertinib. Further in vitro experiments showed that IC50 of PLK1 inhibitors BI 6727 and GSK 461364 in osimertinib-resistant cells were lower than those in sensitive ones. Compared with the mono treatment of osimertinib, PLK1 inhibitors combined with osimertinib behaved significantly stronger effect on the proliferation of osimertinib-resistant cells.

CONCLUSIONS

PLK1 inhibitors have a synergistic effect with osimertinib on osimertinib-resistant NSCLC cells which indicates that they may have potential clinical value in the treatment of NSCLC patients with osimertinib resistance.