Resistance mechanisms to osimertinib in EGFR-mutated advanced non-small-cell lung cancer: A multicentric retrospective French study

Histological transformation of non-small cell lung cancer: Clinical analysis of nine cases

BACKGROUND

Histological transformation is one of the numerous mechanisms of acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs). Given its rarity, the underlying transformational mechanisms, clinical features, and therapeutic prognoses are only studied through limited case reports.

AIM

To analyze the clinical characteristics and underlying mechanisms in non-small cell lung cancer (SCLC) patients with histological transformation after treatment with EGFR-TKIs.

METHODS

We retrospectively investigated nine patients diagnosed with non-SCLC transforming to SCLC, large-cell neuroendocrine carcinoma (LCNEC), or squamous cell carcinoma on re-biopsy after first- or third-generation EGFR-TKIs.

RESULTS

The median age of nine patients was 60 years. Among them, six patients had the EGFR 19del mutation, one had the L858R mutation, and one had wild-type EGFR. The level of plasma NSE was measured in six patients with SCLC or LCNEC transformation when transformation occurred, and five patients had elevated plasma NSE levels. All patients received standard chemotherapy after transformation with the exception of one patient who received chemotherapy and anlotinib.

CONCLUSION

Tumor re-biopsy should be performed routinely when EGFR-TKI therapy fails in lung cancer patients to avoid ignoring histological transformation and to select a subsequent therapeutic strategy. The transformed tumor retained the original EGFR mutation, indicating that histological transformation represents an evolution from the initial tumor.

Significant Benefits of Afatinib and Apatinib in a Refractory Advanced NSCLC Patient Resistant to Osimertinib: A Case Report

EGFR-tyrosine kinase inhibitors (TKIs) have revolutionized the treatment for NSCLC. However, acquired drug resistance often occurs after treatment with EGFR-TKIs. EGFR T790M and C797S mutations are the most common resistance mechanism in patients who failed from first- and third- generation EGFR TKI treatments, respectively. However, there is no standard of care for NSCLC harboring EGFR T790M and C797S in-cis. The present case reports a 69-year-old Chinese man with advanced NSCLC harboring EGFR exon 19-deletion, T790M, cis-C797S, and HER2 amplification who was heavily pre-treated. The patient was then given a combination of afatinib and apatinib and achieved a PFS of more than 10 months. This case showed that afatinib plus apatinib may be a promising therapy for patients with EGFR 19Del-T790M-cis-C797S mutant and HER2 amplified NSCLC.

Resistance Profile of Osimertinib in Pre-treated Patients With EGFR T790M-Mutated Non-small Cell Lung Cancer

Background: Osimertinib efficacy in pre-treated patients with epidermal growth factor receptor (EGFR) T790M-mutated non-small cell lung cancer (NSCLC) has been demonstrated in clinical trials, but real-world data, particularly regarding resistance profile, remains limited. This study aims to analyze the resistance mechanisms acquired after treatment with Osimertinib.

Methods: Clinical outcomes and molecular results from re-biopsies at the time of osimertinib progression of EGFR T790M-mutated NSCLC patient were analyzed.

Results: Twenty-one patients with stage IV adenocarcinoma were included [median 69 years; 57.1% female; 85.7% never-smokers; 23.8% ECOG performance status (PS) ≥2]. Median PFS and OS were 13.4 (95% CI: 8.0–18.9) and 26.4 (95% IC: 8.9–43.8) months, respectively. At the time of analysis, 10 patients had tumor progression (47.6%). T790M loss occurred in 50%, being associated with earlier progression (median PFS 8.1 vs. 21.4 months, p = 0.011). Diverse molecular alterations were identified, including C797S mutation (n = 1), PIK3CA mutation (n = 2), MET amplification (n = 1), CTNNB1 mutation (n = 1), and DCTN1-ALK fusion (n = 1). Histological transformation into small cell carcinoma occurred in one patient.

Conclusions: This real-world life study highlights the relevance of re-biopsy at the time of disease progression, contributing to understand resistance mechanisms and to guide treatment strategies.

Effective degradation of EGFRL858R+T790M mutant proteins by CRBN-based PROTACs through both proteosome and autophagy/lysosome degradation systems

Targeted therapy of treating patients with specific tyrosine kinase inhibitors (TKIs) is currently the standard care for epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer. However, the inevitably developed drug resistance in patients to EGFR TKIs is the biggest obstacle for cancer targeted therapy. About 60% of drug resistance to the 1st generation of EGFR TKIs was resulted from an acquired T790M mutation in the kinase domain of EGFR protein. Proteolysis targeting chimera (PROTAC) is a lately-developed technology to target point of interest proteins for degradation. Because EGFR-mutant lung cancers are highly dependent on EGFR proteins, designing specific PROTAC molecules to degrade EGFR proteins from cancer cells provides a very promising strategy to treat such patients and eradicate drug resistance. Currently, there is no cereblon (CRBN)-based PROTAC reported able to degrade T790M-containing EGFR resistant proteins. In this study, we synthesized two novel CRBN-based EGFR PROTACs, SIAIS125 and SIAIS126, based on EGFR inhibitor canertinib and cereblon ligand pomalidomide. These two degraders displayed potent and selective antitumor activities in EGFR TKI resistant lung cancer cells. Firstly, they could selectively degrade EGFR^L858R+T790M resistant proteins in H1975 cells at the concentration of 30-50 nM, and EGFR^Ex19del proteins in PC9 cells. But they did not degrade EGFR^{Ex19del+T790M} mutant proteins in PC9Brca1 cells or wild type EGFR in A549 lung cancer cells. They could also selectively inhibit the growth of EGFR mutant lung cancer cells but not that of normal cells or A549 cells. Secondly, the degradation of EGFR^L858R+T790M proteins was long lasting up to 72 h. Thirdly, these degraders displayed better inhibition of EGFR phosphorylation in H1975 cells and PC9Brca1 cells comparing to canertinib. Finally, these degraders could also induce significant apoptosis and cell cycles arrest in H1975 cells. Pre-incubation with canertinib, pomalidomide or ubiquitination inhibitor MLN4924 totally blocked EGFR degradation by PROTACs. Mechanistic studies showed that PROTAC could induce autophagy in lung cancer cells. PROTAC-induced EGFR degradation acted through both ubiquitin/proteosome system and ubiquitin/autophagy/lysosome system. Elevating autophagy activities enhanced EGFR degradation and cell apoptosis induced by PROTACs. Our research not only offered a novel PROTAC tool to target EGFR TKI drug resistance in lung cancer, but also firstly demonstrated that the involvement of autophagy/lysosome system in PROTAC- mediated target protein degradation.

Osimertinib in advanced EGFR-T790M mutation-positive non-small cell lung cancer patients treated within the Special Use Medication Program in Spain: OSIREX-Spanish Lung Cancer Group

BACKGROUND

AURA study reported 61% objective response rate and progression-free survival of 9.6 months with osimertinib in patients with EGFR/T790M+ non-small cell lung cancer. Due to lack of real-world data, we proposed this study to describe the experience with osimertinib in Spain.

METHODS

Post-authorization, non-interventional Special Use Medication Program, multicenter, retrospective study in advanced EGFR/T790M+ non-small cell lung cancer. One hundred-fifty five patients were enrolled (August 2016-December 2018) from 30 sites.

PRIMARY OBJECTIVE

progression-free survival. Secondary objectives: toxicity profile, objective response rate, and use of health service resources.

RESULTS

70% women, median age 66. 63.9% were non-smokers and 99% had adenocarcinoma. Most patients had received at least one prior treatment (97%), 91.7% had received previous EGFR-tyrosine kinase inhibitors and 2.8% osimertinib as first-line treatment. At data cutoff, median follow-up was 11.8 months. One hundred-fifty five patients were evaluable for response, 1.3% complete response, 40.6% partial response, 31% stable disease and 11.6% disease progression. Objective response rate was 42%. Median progression-free survival was 9.4 months. Of the 155 patients who received treatment, 76 (49%) did not reported any adverse event, 51% presented some adverse event, most of which were grade 1 or 2. The resource cost study indicates early use is warranted.

CONCLUSION

This study to assess the real-world clinical impact of osimertinib showed high drug activity in pretreated advanced EGFR/T790M+ non-small cell lung cancer, with manageable adverse events.

TRIAL REGISTRATION

Clinical trial registration number: NCT03790397 .

Patterns and Treatment Strategies of Osimertinib Resistance in T790M-Positive Non-Small Cell Lung Cancer: A Pooled Analysis

Introduction

Osimertinib resistance is inevitable. The purpose of this study was to explore the predictive value of pretreatment clinical characteristics in T790M-positive non-small cell lung cancer NSCLC patients for the resistance pattern of osimertinib during tumor progression as well as the treatment strategy.

Methods

We performed a literature search in the NCBI PubMed database to identify relevant articles and completed a pooled analysis based on 29 related published studies. The relationship between clinical characteristics, EGFR mutation type, previous treatment history and the gene mutation pattern at resistance to osimertinib was analyzed.

Results

A total of 38 patients were included in the pooled analysis. Patients with an initial epidermal growth factor receptor EGFR mutation status of 19 deletions were more likely to have T790M loss (HR: 12.187, 95% CI: 2.186–67.945, p = 0.004). Patients with an initial EGFR mutation of L858R were more likely to have C797S mutations (HR: 0.063, 95% CI: 0.011–0.377, p = 0.002). The other factors (age, gender, ethnicity, smoking history, previous EGFR-TKI targeted therapy history, history of radiotherapy and chemotherapy) were not associated with the resistance pattern of osimertinib (all p > 0.05).

Conclusions

The type of EFGR mutation in T790M-positive NSCLC patients prior to treatment can predict the resistance pattern to osimertinib. This finding plays a vital role and theoretical basis in guiding clinicians to formulate treatment strategies at the early stage of treatment and rationally combine drugs to overcome EGFR-TKI resistance.

Novel Resistance Mechanisms to Osimertinib Analysed by Whole-Exome Sequencing in Non-Small Cell Lung Cancer

Purpose

Molecular-based targeted therapy has improved life expectancy for advanced non-small cell lung cancer (NSCLC). However, it does not have to be inevitable that patients receiving third-generation EGFR-TKIs become drug resistant. EGFR C797S and MET amplification are common mechanisms of osimertinib. However, a large part of these potential drug mechanisms remains unknown, and further research is needed.

Methods

Tumour and blood samples from forty advanced NSCLC patients were identified as acquired drug resistant to osimertinib. The NGS panel was applied to detect EGFR C797S and MET amplification in tumour tissues or plasma samples. Whole-exome sequencing was conducted in five pairs of tumour tissues obtained before osimertinib administration and after osimertinib resistance in patients without C797S/cMET amplification.

Results

The overall C797S mutation rate was 20%, and MET amplification was detected in six out of sixteen C797S-negative samples. PDGFRA in the PI3K-AKT-mTOR signalling pathway, RASAL2, RIN3 and SOS2 in the RAS-Raf-ERK signalling pathway, PTK2 in the ERBB signalling pathway and ABCC1 and ABCB5 in the ABC membrane pump system were identified as candidate crucial genes of drug resistance to osimertinib.

Conclusion

EGFR C797S mutation and MET amplification are leading mechanisms for osimertinib resistance in lung cancer. The crucial potential mutated genes defined in our present study may need further validation in a considerable number of lung cancer patients.

An overview of osimertinib as a treatment of non-small cell lung cancer (NSCLC): an update

Introduction: Osimertinib is a third-generation anti-epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), that irreversibly binds to mutant EGFR, specifically to the T790M EGFR mutant non-small cell lung cancer (NSCLC). Since its approval, osimertinib has been tested in multiple scenarios, including the first-line and adjuvant setting of EGFR-mutant disease.Areas covered: The authors summarize the most recent evidence about osimertinib in NSCLC, covering its use as a first-line therapy, its activity on central nervous system metastatic disease, and in elderly patients. Moreover, the authors focus on resistance to this drug and on the therapeutic strategies that may be used to overcome this issue.Expert opinion: Osimertinib is a key player in the treatment ofEGFR mutant NSCLC and will probably be used in earlier clinical settings in the future, giving rise to an emerging variety of resistance mechanisms. These could be potentially overcome in several ways: e.g. as an oligo-progressive disease local therapy, maintaining osimertinib might be a reasonable option; however, for widespread progressive disease, a switch to chemotherapy should be considered. Finally, either liquid biopsy or tissue biopsy might be considered in patients progressing to osimertinib, as they can lead to the identification of potentially targetable resistance mechanisms.

Combination of tissue and liquid biopsy molecular profiling to detect transformation to small cell lung carcinoma during osimertinib treatment

Background:

Histological transformation of advanced non-small cell lung cancer (NSCLC) to small cell lung cancer (SCLC) is one of the mechanisms of resistance to third-generation tyrosine kinase inhibitors (TKIs), such as osimertinib. This acquired TKI resistance is linked to the high degree of tumor heterogeneity and adaptive cellular signaling pathways, including epidermal growth factor receptor (EGFR)-dependent pathways, observed in NSCLC.

Methods:

Here, we investigated a series of paired pre- and post-histological transformation biopsies obtained from three patients initially having a NSCLC with an EGFR^activating mutation treated with first-generation TKI, who then received osimertinib as second-line after EGFR^T790M resistance and, lastly, developed a histological transformation to SCLC. Both tissue and liquid biopsies were analyzed using large panel sequencing approaches at various time points to reconstruct the clonal evolutionary history of the tumor.

Results:

Our complementary analysis of tumor tissue and circulating tumor DNA samples allowed us to better characterize the histological and molecular alterations associated with resistance to osimertinib. SCLC transformation was linked to the presence of several concomitant gene alterations, including EGFR, TP53 and RB1, but also to specific signal bypass, such as EGFR and MET amplifications and activation of the PI3K/AKT/mTOR pathway.

Conclusion:

Our report emphasizes the mutational landscape of SCLC histological transformation and highlights the importance of combining tissue and liquid biopsy profiling before and during osimertinib treatment to predict such histological transformation.

Osimertinib for Front-Line Treatment of Locally Advanced or Metastatic EGFR-Mutant NSCLC Patients: Efficacy, Acquired Resistance and Perspectives for Subsequent Treatments

Non-small cell lung cancer (NSCLC) is one of the most efficient models for precision medicine in oncology. The most appropriate therapeutic for the patient is chosen according to the molecular characteristics of the tumor, schematically distributed between immunogenicity and oncogenic addiction. For this last concept, advanced NSCLC with epidermal growth factor receptor (EGFR) mutation is one of the most illustrative models. EGFR-tyrosine kinase inhibitors (TKIs) are the therapeutic backbone for this type of tumor. The recent development of a third-generation TKI, osimertinib, has been a new step forward in the treatment of NSCLC patients. In this article, we first review the clinical development of osimertinib and highlight its efficacy results. We then present the most frequent tumor escape mechanisms when osimertinib is prescribed in first line: off-target (MET amplification, HER2 amplification, BRAF mutation, gene fusions, histologic transformation) and on-target mechanisms (EGFR mutation). Finally, we discuss subsequent biomarker-driven treatment strategies.

Licochalcone A inhibits EGFR signalling and translationally suppresses survivin expression in human cancer cells

Dysfunction of epidermal growth factor receptor (EGFR) signalling plays a critical role in the oncogenesis of non–small‐cell lung cancer (NSCLC). Here, we reported the natural product, licochalcone A, exhibited a profound anti‐tumour efficacy through directly targeting EGFR signalling. Licochalcone A inhibited in vitro cell growth, colony formation and in vivo tumour growth of either wild‐type (WT) or activating mutation EGFR‐expressed NSCLC cells. Licochalcone A bound with L858R single‐site mutation, exon 19 deletion, L858R/T790M mutation and WT EGFR ex vivo, and impaired EGFR kinase activity both in vitro and in NSCLC cells. The in silico docking study further indicated that licochalcone A interacted with both WT and mutant EGFRs. Moreover, licochalcone A induced apoptosis and decreased survivin protein robustly in NSCLC cells. Mechanistically, we found that treatment with licochalcone A translationally suppressed survivin through inhibiting EGFR downstream kinases ERK1/2 and Akt. Depletion of the translation initiation complex by eIF4E knockdown effectively inhibited survivin expression. In contrast, knockdown of 4E‐BP1 showed the opposite effect and dramatically enhanced survivin protein level. Overall, our data indicate that targeting survivin might be an alternative strategy to sensitize EGFR‐targeted therapy.

The next tier of EGFR resistance mutations in lung cancer

EGFR mutations account for the majority of druggable targets in lung adenocarcinoma. Over the past decades the optimization of EGFR inhibitors revolutionized the treatment options for patients suffering from this disease. The pace of this development was largely dictated by the inevitable emergence of resistance mutations during drug treatment. As a result, a rapid understanding of the structural and molecular biology of the individual mutations is the key for the development of next-generation inhibitors. Currently, the field faces an unprecedented number of combinations of activating mutations with distinct resistance mutations in parallel to the approval of osimertinib as a first-line drug for EGFR-mutant lung cancer. In this review, we present a survey of the diverse landscape of EGFR resistance mechanisms with a focus on new insights into on-target EGFR kinase mutations. We discuss array of mutations, their structural effects on the EGFR kinase domain as well as the most promising strategies to overcome the individual resistance profiles found in lung cancer patients.

An EGFR T790M-mutated lung adenocarcinoma undergoing large-cell neuroendocrine carcinoma transformation after osimertinib therapy: a case report

BACKGROUND

Osimertinib, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor, is selective for both epidermal growth factor receptor tyrosine kinase inhibitor-sensitizing and T790M resistance mutations. Almost all patients who initially respond to an epidermal growth factor receptor tyrosine kinase inhibitor subsequently report disease progression. Epidermal growth factor receptor-dependent resistance mechanisms, bypass pathway activation, and histological transformation have been reported with osimertinib therapy.

CASE PRESENTATION

We report a case of a 64-year-old Asian man with epidermal growth factor receptor T790M-positive adenocarcinoma that transformed to epidermal growth factor receptor T790M-negative large-cell neuroendocrine carcinoma after osimertinib therapy. A prompt rebiopsy revealed a rare mechanism of resistance to epidermal growth factor receptor tyrosine kinase inhibitor, and subsequently treatment with carboplatin and etoposide was effective.

CONCLUSIONS

Despite the promising emergence of circulating tumoral DNA testing, this case report emphasizes the importance of rebiopsy of a progressive epidermal growth factor receptor-mutant tumor.

Tumor Analyses Reveal Squamous Transformation and Off-Target Alterations As Early Resistance Mechanisms to First-line Osimertinib in EGFR-Mutant Lung Cancer

PURPOSE

Patterns of resistance to first-line osimertinib are not well-established and have primarily been evaluated using plasma assays, which cannot detect histologic transformation and have differential sensitivity for copy number changes and chromosomal rearrangements.

EXPERIMENTAL DESIGN

To characterize mechanisms of resistance to osimertinib, patients with metastatic EGFR-mutant lung cancers who received osimertinib at Memorial Sloan Kettering Cancer Center and had next-generation sequencing performed on tumor tissue before osimertinib initiation and after progression were identified.

RESULTS

Among 62 patients who met eligibility criteria, histologic transformation, primarily squamous transformation, was identified in 15% of first-line osimertinib cases and 14% of later-line cases. Nineteen percent (5/27) of patients treated with first-line osimertinib had off-target genetic resistance (2 MET amplification, 1 KRAS mutation, 1 RET fusion, and 1 BRAF fusion) whereas 4% (1/27) had an acquired EGFR mutation (EGFR G724S). Patients with squamous transformation exhibited considerable genomic complexity; acquired PIK3CA mutation, chromosome 3q amplification, and FGF amplification were all seen. Patients with transformation had shorter time on osimertinib and shorter survival compared with patients with on-target resistance. Initial EGFR sensitizing mutation, time on osimertinib treatment, and line of therapy also influenced resistance mechanism that emerged. The compound mutation EGFR S768 + V769L and the mutation MET H1094Y were identified and validated as resistance mechanisms with potential treatment options.

CONCLUSIONS

Histologic transformation and other off-target molecular alterations are frequent early emerging resistance mechanisms to osimertinib and are associated with poor clinical outcomes.See related commentary by Piotrowska and Hata, p. 2441.

Formononetin inhibits tumor growth by suppression of EGFR-Akt-Mcl-1 axis in non-small cell lung cancer

Background

Epidermal growth factor receptor (EGFR) activating mutations play crucial roles in the tumorigenesis of human non-small cell lung cancer (NSCLC). The mechanism regarding how EGFR signaling regulates myeloid cell leukemia sequence 1 (Mcl-1) protein stability and ubiquitination remains undefined.

Methods

MTS assay was used for natural product library screening. The effect of formononetin (Formo) on NSCLC cells was determined by MTS assay and soft agar assay. Molecular modeling was performed to analyze the potential different binding modes between Formo and EGFR WT or mutants. Mcl-1 protein level and the inhibitory effect of Formo on EGFR signaling were examined by immunoblot, in vitro kinase assay, in vitro pulldown and ATP competition assays, co-immunoprecipitation assay, ubiquitination analysis, in vivo xenograft model, and immunohistochemical staining.

Results

Formo was identified as an EGFR inhibitor by a 98 commercially available natural product screening. Formo suppresses WT and mutant EGFR kinases activity in vitro, ex vivo, and in vivo. Molecular modeling indicates that Formo docks into the ATP-binding pocket of both WT and mutant EGFR. Formo inhibits EGFR-Akt signaling, which in turn activates GSK3β and promotes Mcl-1 phosphorylation in NSCLC cells. Treatment with Formo enhances the interaction between Mcl-1 and SCF^Fbw7, which eventually promotes Mcl-1 ubiquitination and degradation. Depletion of either GSK3β or SCF^Fbw7 compromised Formo-induced Mcl-1 downregulation. Finally, Formo inhibits the in vivo tumor growth in a xenograft mouse model.

Conclusion

This study highlights the importance of promoting ubiquitination-dependent Mcl-1 turnover might be an alternative strategy to enhance the anti-tumor efficacy of EGFR-TKI.

Secondary Resistant Mutations to Small Molecule Inhibitors in Cancer Cells

Secondary resistant mutations in cancer cells arise in response to certain small molecule inhibitors. These mutations inevitably cause recurrence and often progression to a more aggressive form. Resistant mutations may manifest in various forms. For example, some mutations decrease or abrogate the affinity of the drug for the protein. Others restore the function of the enzyme even in the presence of the inhibitor. In some cases, resistance is acquired through activation of a parallel pathway which bypasses the function of the drug targeted pathway. The Catalogue of Somatic Mutations in Cancer (COSMIC) produced a compendium of resistant mutations to small molecule inhibitors reported in the literature. Here, we build on these data and provide a comprehensive review of resistant mutations in cancers. We also discuss mechanistic parallels of resistance.

Construction and Validation of a Protein Prognostic Model for Lung Squamous Cell Carcinoma

Lung squamous cell carcinoma (LUSCC), as the major type of lung cancer, has high morbidity and mortality rates. The prognostic markers for LUSCC are much fewer than lung adenocarcinoma. Besides, protein biomarkers have advantages of economy, accuracy and stability. The aim of this study was to construct a protein prognostic model for LUSCC. The protein expression data of LUSCC were downloaded from The Cancer Protein Atlas (TCPA) database. Clinical data of LUSCC patients were downloaded from The Cancer Genome Atlas (TCGA) database. A total of 237 proteins were identified from 325 cases of LUSCC patients based on the TCPA and TCGA database. According to Kaplan-Meier survival analysis, univariate and multivariate Cox analysis, a prognostic prediction model was established which was consisted of 6 proteins (CHK1_pS345, CHK2, IRS1, PAXILLIN, BRCA2 and BRAF_pS445). After calculating the risk values of each patient according to the coefficient of each protein in the risk model, the LUSCC patients were divided into high risk group and low risk group. The survival analysis demonstrated that there was significant difference between these two groups (p= 4.877e-05). The area under the curve (AUC) value of the receiver operating characteristic (ROC) curve was 0.699, which suggesting that the prognostic risk model could effectively predict the survival of LUSCC patients. Univariate and multivariate analysis indicated that this prognostic model could be used as independent prognosis factors for LUSCC patients. Proteins co-expression analysis showed that there were 21 proteins co-expressed with the proteins in the risk model. In conclusion, our study constructed a protein prognostic model, which could effectively predict the prognosis of LUSCC patients.