MET amplification results in heterogeneous responses to osimertinib in EGFR-mutant lung cancer treated with erlotinib

Anlotinib Plus Osimertinib in Osimertinib-Resistant Nonsquamous Nonsmall Cell Lung Cancer With Gradual Progression: A Retrospective Study

BACKGROUND

Previous studies have shown that anlotinib plus third-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) overcome acquired resistance to EGFR-TKIs in patients with advanced EGFR-mutant nonsmall cell lung cancer (NSCLC). This study aimed to retrospectively evaluate whether anlotinib plus osimertinib overcame acquired resistance in patients with nsq-NSCLC who gradually progressed after first-line EGFR-TKI treatment.

METHODS

This study included patients with nsq-NSCLC who developed gradual progression after first-line osimertinib treatment, underwent an anlotinib plus osimertinib regimen in Tianjin Medical University General Hospital, and had available data from October 8, 2020 to October 14, 2023. Outcomes included the efficacy, assessed by progression-free survival (PFS), of anlotinib plus osimertinib treatment (PFS1) and prior osimertinib treatment (PFS2), to disease progression, objective response rate (ORR), disease control rate (DCR), and safety as assessed by the incidence of treatment-related toxicities.

RESULTS

A total of 28 patients with nsq-NSCLC were included, with a median follow-up of 12 months (range, 7.8-16.2). Treatment with anlotinib plus osimertinib led to a median PFS1 of 10.0 months (95% confidence interval [CI], 8.4-11.6). With a median follow-up from prior osimertinib therapy of 31.5 months (range, 20.8-42.2), the median PFS2 was 22.0 months (95% CI, 17.5-26.5). The ORR to combination therapy was 3.6% (95% CI, 0.2-20.2) and the DCR was 85.7% (95% CI, 67.3-96.0). All patients experienced treatment-related toxicities, with 10.7% showing grade 3, and none were grade ≥ 4.

CONCLUSIONS

Anlotinib plus osimertinib exhibited encouraginsg anti-tumor activity and had a manageable safety profile in patients with nsq-NSCLC showing gradual progression on osimertinib.

Silencing of LINC01278 promotes sensitivity of non-small cell lung cancer cells to osimertinib by targeting miR-324-3p/ZFX axis

Osimertinib has been demonstrated to be effective for improving the prognosis of patients with epidermal growth factor receptor mutation-positive lung cancer. However, osimertinib resistance inevitably emerges throughout the treatment course. This study explored the function and mechanism of long noncoding RNA LINC01278 in osimertinib-resistant NSCLC cells. Osimertinib-resistant non-small cell lung cancer (NSCLC) cells were established by treating PC9 and HCC827 cells with increasing doses of osimertinib for over 6 months. LINC01278 expression in parental and drug-resistant cells (PC9-OR and HCC827-OR) was measured by polymerase chain reaction. Cell counting kit 8 assays were used to examine cell viability and half-maximal inhibitory concentration values. The effects of LINC01278 knockdown on cell proliferation and apoptosis were measured by colony formation assays and flow cytometry. A luciferase reporter assay was performed to verify the interaction between LINC01278 and miR-324-3p or the binding ability between miR-324-3p and ZFX. Protein levels of ZFX and apoptotic markers in NSCLC cells were measured by western blotting. As shown by experimental results, LINC01278 was highly expressed in osimertinib-resistant NSCLC cells compared to its expression in parental cells. The silencing of LINC01278 improved the sensitivity of drug-resistant cells towards osimertinib. LINC1278 depletion inhibited osimertinib-resistant cell proliferation while promoting cell apoptosis. LINC01278 interacted with miR-324-3p to regulate ZFX expression. ZFX could be targeted by miR-324-3p in PC9-OR and HCC827-OR cells. ZFX overexpression counteracted the suppressive impact of LINC01278 silencing on the malignant behavior of PC9-OR and HCC827-OR cells. In conclusion, LINC01278 knockdown alleviates osimertinib resistance of NSCLC cells by regulating downstream miR-324-3p and ZFX.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-024-00673-8.

The cell line models to study tyrosine kinase inhibitors in non-small cell lung cancer with mutations in the epidermal growth factor receptor: A scoping review

Non-Small Cell Lung Cancer (NSCLC) represents ∼85% of all lung cancers and ∼15-20% of them are characterized by mutations affecting the Epidermal Growth Factor Receptor (EGFR). For several years now, a class of tyrosine kinase inhibitors was developed, targeting sensitive mutations affecting the EGFR (EGFR-TKIs). To date, the main burden of the TKIs employment is due to the onset of resistance mutations. This scoping review aims to resume the current situation about the cell line models employed for the in vitro evaluation of resistance mechanisms induced by EGFR-TKIs in oncogene-addicted NSCLC. Adenocarcinoma results the most studied NSCLC histotype with the H1650, H1975, HCC827 and PC9 mutated cell lines, while Gefitinib and Osimertinib the most investigated inhibitors. Overall, data collected frame the current advancement of this topic, showing a plethora of approaches pursued to overcome the TKIs resistance, from RNA-mediated strategies to the innovative combination therapies.

Characterization of circRNAs in established osimertinib‑resistant non‑small cell lung cancer cell lines

Drug resistance is an urgent problem to be solved in the treatment of non‑small‑cell lung cancer (NSCLC). Osimertinib is a third‑generation EGFR‑tyrosine kinase inhibitor, which can improve the efficacy and quality of life of patients; however, the inevitable resistance after long‑term use of osimertinib often leads to treatment failure. Cell lines are key tools for basic and preclinical studies. At present, few osimertinib‑resistant cell lines (HCC827‑OR and H1975‑OR) have been established. In the present study, osimertinib‑resistant cell lines were established by gradually increasing the drug concentration. Half‑maximal inhibitory concentration (IC50), cell morphology, whole exon sequencing, Cell Counting Kit‑8 assay, EdU staining and flow cytometry were used to evaluate the osimertinib‑resistant cell lines. Western blot analysis was used to detect the expression levels of key proteins involved in osimertinib resistance. The circular RNA (circRNA) expression profile was identified by RNA sequencing (RNA‑seq) analysis of HCC827, HCC827‑OR, H1975 and H1975‑OR cells. Subsequently, the biological roles of differentially expressed circRNAs were explored in in vitro studies. Osimertinib‑resistant cell lines were successfully established via treatment with an increasing concentration of osimertinib. Osimertinib IC50 and proliferation of resistant cells were much higher than those of sensitive cells. Notably, phosphorylated (p)‑AKT and p‑ERK were markedly activated in resistant cells, and the inhibitory effect of osimertinib on p‑AKT and p‑ERK was weaker in resistant cells than that in parental cells. RNA‑seq analysis identified differentially expressed circRNAs in HCC827, HCC827‑OR, H1975 and H1975‑OR cells. The most dysregulated circRNAs (circPDLIM5 and circPPP4R1) were selected for further functional study. Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that the host genes of differentially expressed circRNAs were associated with 'endocytosis' and 'regulation of autophagy'. In conclusion, the present study established osimertinib‑resistant cell lines and revealed that circRNAs may serve as a promising biomarker in NSCLC osimertinib resistance.

Real-World Data on Combined EGFR-TKI and Crizotinib Treatment for Acquired and De Novo MET Amplification in Patients with Metastatic EGFR-Mutated NSCLC

Amplification of the mesenchymal epithelial transition (MET) gene is a mechanism of acquired resistance to epidermal growth factor receptor (EGFR)-tyrosine-kinase-inhibitors (TKIs) in over 20% of patients with advanced EGFR-mutated (EGFRm+) non-small lung cancer (NSCLC). However, it may also occur de novo in 2-8% of EGFRm+ NSCLC cases as a potential mechanism of intrinsic resistance. These patients represent a group with unmet needs, since there is no standard therapy currently approved. Several new MET inhibitors are being investigated in clinical trials, but the results are awaited. Meanwhile, as an alternative strategy, combinations of EGFR-TKIs with the MET/ALK/ROS1-TKI Crizotinib may be used in this setting, despite this use is principally off-label. Thus, we studied five of these MET amplified cases receiving EGFR-TKI and Crizotinib doublet after progression on EGFR-TKI treatment to assess the benefits and challenges related to this combination and the possible occurrence of genomic and phenotypic co-alterations. Furthermore, we compared our cases with other real-world reports on Crizotinib/EGFR-TKI combinations, which appeared effective, especially in patients with high-level MET amplification. Yet, we observed that the co-occurrence of other genomic and phenotypical alterations may affect the response to combined EGFR-TKI and Crizotinib. Finally, given the heterogeneity of MET amplification, the diagnostic methods for assessing it may be discrepant. In this respect, we observed that for optimal detection, immunohistochemistry, fluorescence in situ hybridization, and next-generation sequencing should be used together, as these methods possess different sensitivities and complement each other in characterizing MET amplification. Additionally, we addressed the issue of managing EGFR-mutated NSCLC patients with de novo MET amplification causing primary EGFR-TKI resistance. We conclude that, while data from clinical trials with new MET inhibitors are still pending, adding Crizotinib to EGFR-TKI in NSCLC patients acquiring MET amplification at progression on EGFR-TKI monotherapy is a reasonable approach, with a progression-free survival of 3-19 months.

Therapeutic strategies for EGFR-mutated non-small cell lung cancer patients with osimertinib resistance

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are the preferential options for advanced non-small cell lung cancer (NSCLC) patients harboring EGFR mutations. Osimertinib is a potent irreversible third-generation EGFR-TKI targeting EGFR mutations but has little effect on wild-type EGFR. In view of its remarkable efficacy and manageable safety, osimertinib was recommended as the standard first-line treatment for advanced or metastatic NSCLC patients with EGFR mutations. However, as the other EGFR-TKIs, osimertinib will inevitably develop acquired resistance, which limits its efficacy on the treatment of EGFR-mutated NSCLC patients. The etiology of triggering osimertinib resistance is complex including EGFR-dependent and EGFR-independent pathways, and different therapeutic strategies for the NSCLC patients with osimertinib resistance have been developed. Herein, we comprehensively summarized the resistance mechanisms of osimertinib and discuss in detail the potential therapeutic strategies for EGFR-mutated NSCLC patients suffering osimertinib resistance for the sake of the improvement of survival and further achievement of precise medicine.

Durable Response of Dabrafenib, Trametinib, and Capmatinib in an NSCLC Patient With Co-Existing BRAF-KIAA1549 Fusion and MET Amplification: A Case Report

BRAF fusions are rare driver oncogenes in non-small cell lung cancer (NSCLC). Similar with BRAF V600E mutation, it could also activate the MAPK signaling pathway. There are a few case reports which had indicated the potential response to BRAF inhibitors and its important role as de novo driver mutation. In addition, the co-occurring MET amplification has been defined as a poor prognostic factor in patients with epidermal growth factor receptor (EGFR) mutant NSCLC. Currently, there are ongoing clinical trials which investigate the MET amplification as a therapeutic target in patients with EGFR mutant NSCLC and acquired resistance to osimertinib, which imply that the MET amplification also had a therapeutic significance. However, the co-occurring MET amplification had not been studied in patients with BRAF fusion before. A 67-year-old man was diagnosed with metastatic poorly-differentiated adenocarcinoma. He received first-line therapy with the combination of pembrolizumab and chemotherapy because the genomic test revealed wild-type EGFR, and negativity of ALK and ROS1 by immunohistochemical stain. Upon disease progression, the next-generation sequencing revealed co-occurring KIAA1549-BRAF fusion and MET amplification. Subsequent dabrafenib, trametinib, and capmatinib combination therapy showed a remarkable treatment effect. The combination therapy targeting the co-occurring driver mutations is a potential effective treatment for NSCLC patients. Further prospective study is still warranted to investigate the role of co-occurring driver mutations and the relevant treatment strategy.

LS-106, a novel EGFR inhibitor targeting C797S, exhibits antitumor activities both in vitro and in vivo

With the wide clinical use of the third-generation epidermal growth factor receptor (EGFR) inhibitor osimertinib for the treatment of EGFR-mutated non-small cell lung cancer (NSCLC), acquired resistance caused by EGFR C797S tertiary mutation has become a concern. Therefore, fourth-generation EGFR inhibitors that could overcome this mutation have gained increasing attention in recent years. Here, we identified LS-106 as a novel EGFR inhibitor against C797S mutation and evaluated its antitumor activity both in vitro and in vivo. In cell-free assay, LS-106 potently inhibited the kinase activities of EGFR19del/T790M/C797S and EGFRL858R/T790M/C797S with IC50 values of 2.4 nmol/L and 3.1 nmol/L, respectively, which was more potent than osimertinib. Meanwhile, LS-106 exhibited comparable kinase inhibitory effect to osimertinib on EGFRL858R/T790M and wild-type EGFR. Results from cellular experiments demonstrated that LS-106 potently blocked the phosphorylation of EGFR C797S triple mutations in the constructed BaF3 cells that highly expressed EGFR19del/T790M/C797S or EGFRL858R/T790M/C797S , and thus inhibited the proliferation of these cells. We also constructed tumor cells harboring EGFR19del/T790M/C797S (named PC-9-OR cells) using the CRISPR/Cas9 system and found that LS-106 markedly suppressed the activation of EGFR19del/T790M/C797S and the proliferation of PC-9-OR cells. Moreover, cells harboring EGFR19del/T790M/C797S underwent remarkable apoptosis upon LS-106 treatment. In vivo experiments further demonstrated that oral administration of LS-106 caused significant tumor regression in a PC-9-OR xenograft model, with a tumor growth inhibition rate (TGI) of 83.5% and 136.6% at doses of 30 and 60 mg/kg, respectively. Taken together, we identified LS-106 as a novel fourth-generation EGFR inhibitor against C797S mutation and confirmed its preclinical antitumor effects in C797S-triple-mutant tumor models.

Advanced NSCLC Patients With EGFR T790M Harboring TP53 R273C or KRAS G12V Cannot Benefit From Osimertinib Based on a Clinical Multicentre Study by Tissue and Liquid Biopsy

Background

Non-small cell lung cancer (NSCLC) patients treated with first-generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) almost always acquire resistance, and the development of novel techniques analyzing circulating tumor DNA (ctDNA) have made it possible for liquid biopsy to detect genetic alterations from limited amount of DNA with less invasiveness. While a large amount of patients with EGFR exon 21 p.Thr790 Met (T790M) benefited from osimertinib treatment, acquired resistance to osimertinb has subsequently become a growing challenge.

Methods

We performed tissue and liquid rebiopsy on 50 patients with EGFR-mutant NSCLC who acquired resistance to first-generation EGFR-TKIs. Plasma samples underwent droplet digital PCR (ddPCR) and next-generation sequencing (NGS) examinations. Corresponding tissue samples underwent NGS and Cobas^® EGFR Mutation Test v2 (Cobas) examinations.

Results

Of the 50 patients evaluated, the mutation detection rates of liquid biopsy group and tissue biopsy group demonstrated no significant differences (41/48, 85.4% vs. 44/48, 91.7%; OR=0.53, 95% CI=0.15 to 1.95). Overall concordance, defined as the proportion of patients for whom at least one identical genomic alteration was identified in both tissue and plasma, was 78.3% (36/46, 95% CI=0.39 to 2.69). Moreover, our results showed that almost half of the patients (46%, 23/50) resistant to first-generation EGFR-TKI harbored p.Thr790 Met (T790M) mutation. 82.6% (19/23) of the T790M positive patients were analyzed by liquid biopsy and 60.9% (14/23) by tumor tissue sequencing. Meanwhile, a wide range of uncommon mutations was detected, and novel mechanisms of osimertinib resistance were discovered. In addition, 16.7% (2/12) of the T790M positive patients with either TP53 R237C or KRAS G12V failed to benefit from the subsequent osimertinib treatment.

Conclusion

Our results emphasized that liquid biopsy is applicable to analyze the drug resistance mechanisms of NSCLC patients treated with EGFR-TKIs. Moreover, we discovered two uncommon mutations, TP53 R273C and KRAS G12V, which attenuates the effectiveness of osimertinib.

MET amplification results in heterogeneous responses to osimertinib in EGFR-mutant lung cancer treated with erlotinib

The third‐generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR‐TKI) osimertinib is approved for untreated, or previously EGFR‐TKI–treated T790M‐positive EGFR‐mutated non‐small cell lung carcinoma (NSCLC). We investigated the heterogeneity of responses to osimertinib and its underlying mechanisms. A patient with EGFR‐L858R–mutated NSCLC was treated with erlotinib. Following treatment, he developed brain and multiple bone metastases and was eventually diagnosed with NSCLC with EGFR‐T790M mutation. The responses of various tumor specimens to osimertinib were heterogeneous. We investigated EGFR‐T790M and MET amplification using PCR and FISH in autopsy specimens of the cervical spine, lumbar spine, and brain. We established the KNZ osimertinib‐resistant (KNZ_OR) tumor cell line with MET amplification using a cervical spine lesion that was intrinsically resistant to osimertinib. We evaluated the effects of MET knockdown and MET inhibitor on KNZ_OR cell sensitivity to osimertinib in vitro and in vivo. Osimertinib‐resistant lesions (cervical spine and brain) showed EGFR‐L858R and MET amplification, but not EGFR‐T790M, whereas osimertinib‐sensitive lesions (lumbar spine) showed EGFR‐L858R and ‐T790, but not MET amplification. Osimertinib decreased the association of amplified MET with L858R‐mutated EGFR but increased that with human epidermal growth factor receptor 3 in KNZ_OR cells. MET knockdown or MET inhibitor sensitized KNZ_OR cells to osimertinib in vitro, indicating that MET amplification induced osimertinib resistance. Combination with osimertinib plus crizotinib induced tumor shrinkage in the KNZ_OR xenograft model. Hence, MET amplification might induce heterogeneous responses to osimertinib in EGFR‐mutated NSCLC. Further investigations on mutated EGFR and amplified MET might lead to the development of effective therapies.