Poziotinib for EGFR exon 20-mutant NSCLC: Clinical efficacy, resistance mechanisms, and impact of insertion location on drug sensitivity

EGFR exon20 insertion mutations in non-small cell lung cancer: Clinical implications and recent advances in targeted therapies

The advent of targeted therapies for oncogenic mutations has led to a major paradigm shift in the management of non-small cell lung cancer (NSCLC). Molecular targets, such as epidermal growth factor receptor (EGFR)-activating mutations in the region of exons 18 through 21 are the most common oncogenic driver in NSCLC. Classical activating mutations, such as in-frame deletions in exon 19 and point mutations in exon 21 (L858R), are strong predictors for good clinical response to the approved EGFR-tyrosine kinase inhibitors (EGFR-TKIs). However, low frequency mutations occurring within exon 20 (ex20ins) have poorer responses to first/second generation EGFR-TKIs. Moreover, patients with NSCLC harboring EGFR ex20ins are known to have poorer prognosis than those with other EGFR-TKI sensitive mutations, leading to unmet clinical need of novel specific therapeutic options. Rapid changes in molecular diagnostics identifying specific causes have hastened the translation of diagnostic recommendations into clinical practice. Emergence of treatment strategies targeting EGFR ex20ins, such as newer EGFR-TKIs with increased specificity and novel approaches using bispecific monoclonal antibodies, may hold promising therapeutic options in the near future. In this review, we describe the structural, molecular characteristics, and detection strategies of EGFR ex20ins mutations and summarize the latest clinical data on approved treatments and emerging therapies for patients with NSCLC harboring EGFR ex20ins mutations. Further, we will discuss the response heterogeneity of ex20ins mutations to new drugs and acquired drug resistance mechanisms.

Structural Mechanism and Inhibitors Targeting EGFR Exon 20 Insertion (Ex20ins) Mutations

Epidermal growth factor receptor (EGFR) targeted therapy is one of the most important and effective strategies to combat EGFR mutant nonsmall-cell lung cancer (NSCLC). However, a substantial number of patients bearing EGFR exon 20 insertion (Ex20ins) mutations respond poorly to common EGFR targeted therapies. This clinical need remained unmet until recently, when the EGFR Ex20ins mutation inhibitor mobocertinib was approved by the FDA. Despite this progress, the structural mechanisms of EGFR Ex20ins mutation resistance and characterization of inhibitor binding modes have not been systematically summarized. Herein, we analyze the structural mechanisms for ligand binding and resistance and summarize recent developments for the reported inhibitors of EGFR Ex20ins mutations. Furthermore, this Perspective aims to provide insights for the design of the next generation of EGFR Ex20ins inhibitors.

Safety, Tolerability, and Antitumor Activity of Zipalertinib Among Patients With Non-Small-Cell Lung Cancer Harboring Epidermal Growth Factor Receptor Exon 20 Insertions

PURPOSE

Although several agents targeting epidermal growth factor receptor (EGFR) exon 20 insertions (ex20ins) have recently been approved by the US Food and Drug Administration, toxicities related to the inhibition of wild-type (WT) EGFR are common with these agents and affect overall tolerability. Zipalertinib (CLN-081, TAS6417) is an oral EGFR tyrosine kinase inhibitor (TKI) with a novel pyrrolopyrimidine scaffold leading to enhanced selectivity for EGFR ex20ins-mutant versus WT EGFR with potent inhibition of cell growth in EGFR ex20ins-positive cell lines.

METHODS

This phase 1/2a study of zipalertinib enrolled patients with recurrent or metastatic EGFR ex20ins-mutant non-small-cell lung cancer (NSCLC) previously treated with platinum-based chemotherapy.

RESULTS

Seventy-three patients were treated with zipalertinib at dose levels including 30, 45, 65, 100, and 150 mg orally twice a day. Patients were predominantly female (56%), had a median age of 64 years, and were heavily pretreated (median previous systemic therapies 2, range 1-9). Thirty six percent of patients had received previous non-ex20ins EGFR TKIs and 3/73 (4.1%) patients received previous EGFR ex20ins TKIs. The most frequently reported treatment-related adverse events of any grade included rash (80%), paronychia (32%), diarrhea (30%), and fatigue (21%). No cases of grade 3 or higher drug-related rash or diarrhea were observed at 100 mg twice a day or below. Objective responses occurred across all zipalertinib dose levels tested, with confirmed partial response (PR) observed in 28/73 (38.4%) response-evaluable patients. Confirmed PRs were seen in 16/39 (41%) response-evaluable patients at the dose of 100 mg twice a day.

CONCLUSION

Zipalertinib has encouraging preliminary antitumor activity in heavily pretreated patients with EGFR ex20ins-mutant NSCLC, with an acceptable safety profile, including low frequency of high-grade diarrhea and rash.

Targeted therapies in non-small cell lung cancer: present and future

Lung cancer is the leading cause of malignancy-related death in the United States and the second most common cancer diagnosis worldwide. In the last two decades, lung cancer treatment has evolved to include advances in the development of mutation-based targeting, immunotherapy, radiation therapy, and minimally invasive surgical techniques. The discovery of lung cancer as a molecularly heterogeneous disease has driven investigation into the development of targeted therapies resulting in improved patient outcomes. Despite these advances, there remain opportunities, through further investigation of mechanisms of resistance, to develop novel therapeutics that better direct the personalization of lung cancer therapy. In this review, we highlight developments in the evolution of targeted therapies in non-small cell lung cancer, as well as future directions shaped by emerging patterns of resistance.

A real-world study of the efficacy and safety of furmonertinib for patients with non-small cell lung cancer with EGFR exon 20 insertion mutations

BACKGROUND

Furmonertinib is a novel third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI). A phase Ib study (FAVOUR, NCT04858958) initially demonstrated the efficacy of furmonertinib in non-small cell lung cancer (NSCLC) with EGFR exon 20 insertion (ex20ins). This study aimed to investigate the real-world efficacy and safety of furmonertinib in patients with advanced NSCLC with EGFR ex20ins.

METHODS

We retrospectively examined patients with advanced NSCLC with EGFR ex20ins having complete follow-up data, who were treated with furmonertinib from April 14, 2021, to March 15, 2022, at our institution and multiple hospitals in China. Objective response rate (ORR), disease control rate (DCR), 6-month progression-free survival (PFS) rates and treatment related adverse events (TRAEs) were assessed.

RESULTS

This study included 53 patients with advanced NSCLC with EGFR ex20ins. A767_V769dup (28.3%) and S768_D770dup (11.3%) are the major variants. The ORR and DCR were 37.7% (20/53) and 92.5% (49/53), respectively. The 6-month PFS rate was 69.4% (95% CI 53.7-85.1%). The ORR of patients in the 240 mg once-daily dosage group was higher (42.9%) than that of patients in the 80 mg once-daily (25.0%) and 160 mg once-daily (39.5%) groups, but with no statistically significant difference (P = 0.816). The ORR of furmonertinib is not dependent on insertion location (P = 0.893). Patients with central nervous system (CNS) metastases at baseline responded similarly to those without CNS metastases (ORR: 33.3% vs. 40.6%, P = 0.773). The most common AEs were diarrhea (26.4%) and rash (26.4%). No grade ≥ 3 TRAEs were observed. No statistically significant difference was observed in the incidence of TRAEs between dosage groups (P = 0.271).

CONCLUSIONS

Furmonertinib has shown encouraging antitumor activity and CNS activity in patients with advanced NSCLC with EGFR ex20ins. Moreover, furmonertinib had a good safety profile and no dose-dependent toxicity.

EGFR exon 20 insertion mutations and ERBB2 mutations in lung cancer: a narrative review on approved targeted therapies from oral kinase inhibitors to antibody-drug conjugates

Background and Objective

This review will provide an overview of EGFR and ERBB2 mutations in non-small-cell lung cancer (NSCLC) with a focus on recent clinical approvals.

Methods

We obtained data from the literature in accordance with narrative review reporting guidelines.

Key Content and Findings

EGFR mutations are present in up to 15-20% of all NSCLCs; amongst these, 10% correspond to kinase domain insertions in exon 20. Structurally similar, ERBB2 (HER2) mutations occurs in 1-4% of NSCLCs, mostly consisting of insertions or point mutations. The majority of EGFR exon 20 insertions occur within the loop following the regulatory C-helix and activate the kinase domain of EGFR without generating a therapeutic window to gefitinib, erlotinib, afatinib, dacomitinib or osimertinib. Mobocertinib represents a novel class of covalent EGFR inhibitors with a modest therapeutic window to these mutants and induces anti-tumor responses in a portion of patients [at 160 mg/day: response rate of <30% with duration of response (DoR) >17 months and progression-free survival (PFS) of >7 months] albeit with mucocutaneous and gastrointestinal toxicities. The bi-specific EGFR-MET antibody amivantamab-vmjw has modest but broad preclinical activity in EGFR-driven cancers and specifically for EGFR exon 20 insertion-mutated NSCLC has response rates <40% and PFS of <8.5 months at the cost of both infusion-related plus on-target toxicities. Both drugs were approved in 2021. The clinical development of kinase inhibitors for ERBB2-mutated NSCLC has been thwarted by mucocutaneous/gastrointestinal toxicities that preclude a pathway for drug approval, as the case of poziotinib. However, the activation of ERBB2 has allowed for repurposing of antibody-drug conjugates (ADCs) that target ERBB2 with cytotoxic payloads. The FDA approved fam-trastuzumab deruxtecan-nxki in 2022 for NSCLC based on response rate of >55%, DoR >9 months, PFS >8 months and manageable adverse events (including cytopenias, nausea and less commonly pneumonitis). Other therapies in clinical development include sunvozertinib and zipalertinib, among others. In addition, traditional cytotoxic chemotherapy has some activity in these tumors.

Conclusions

The approvals of mobocertinib, amivantamab, and trastuzumab deruxtecan represent the first examples of precision oncology for EGFR exon 20 insertion-mutated and ERBB2-mutated NSCLCs.

Real-World Clinical Outcomes for Patients with EGFR and HER2 Exon 20 Insertion-Mutated Non-Small-Cell Lung Cancer

(1) Background: Exon 20 insertion mutations (ex20ins) in EGFR and HER2 are uncommon driver mutations in non-small-cell lung cancer (NSCLC), with a poor prognosis and few targeted therapy options, and there are limited real-world data. Here, we report the clinicopathologic features and outcomes for patients with ex20ins NSCLC across British Columbia, Canada. (2) Methods: NSCLC patients with ex20ins in EGFR or HER2 were identified via tumour testing between 1 January 2016 and 31 December 2021 (n = 7233). Data were collected by chart review. Survival analyses were performed using the Kaplan-Meier method using the log-rank test. (3) Results: A total of 131 patients were identified. The median age was 66. Thirty-three percent of patients had brain metastases. For the EGFR cohort, the median OS was 18.6 months for patients who received any systemic therapy (ST) vs. 2.6 months for patients who did not (p < 0.001). Median OS was similar for patients treated with ex20ins-specific tyrosine kinase inhibitors (TKIs) vs. other STs (18.6 vs. 15.9 months; p = 0.463). The median first-line PFS was 4.1 vs. 7.4 months for patients treated with a TKI vs. other ST (p = 0.744). For the HER2 cohort, the median OS was 9.0 months for patients who received any ST vs. 4.9 months for patients who did not (p = 0.015). The median OS was 23.0 months for patients treated with an ex20ins TKI vs. 5.6 months for patients who were not (p = 0.019). The median first-line PFS was 5.4 vs. 2.1 months for patients treated with a TKI vs. other ST (p = 0.343). (4) Conclusions: Overall survival was significantly longer among ex20ins patients who received any systemic therapy vs. those who did not. Overall survival was significantly better among HER2 ex20ins patients who received ex20ins-specific TKIs.

Overcoming MET-mediated resistance in oncogene-driven NSCLC

This study evaluates the efficacy of combining targeted therapies with MET or SHP2 inhibitors to overcome MET-mediated resistance in different NSCLC subtypes. A prevalence study was conducted for MET amplification and overexpression in samples from patients with NSCLC who relapsed on ALK, ROS1, or RET tyrosine kinase inhibitors. MET-mediated resistance was detected in 37.5% of tissue biopsies, which allow the detection of MET overexpression, compared to 7.4% of liquid biopsies. The development of drug resistance by MET overexpression was confirmed in EGFRex19del-, KRASG12C-, HER2ex20ins-, and TPM3-NTRK1-mutant cell lines. The combination of targeted therapy with MET or SHP2 inhibitors was found to overcome MET-mediated resistance in both in vitro and in vivo assays. This study highlights the importance of considering MET overexpression as a resistance driver to NSCLC targeted therapies to better identify patients who could potentially benefit from combination approaches with MET or SHP2 inhibitors.

Discovery of YK-029A, a novel mutant EGFR inhibitor targeting both T790 M and exon 20 insertion mutations, as a treatment for NSCLC

Although traditional EGFR-TKIs have advanced the treatment landscape of NSCLC with sensitive driver mutations (del19 or L858R), some NSCLC patients with EGFR exon 20 insertion mutations have been left with few effective therapies. The development of novel TKIs is still in progress. Herein, we describe the structure-guided design of a novel selective and orally bioavailable inhibitor, YK-029A, which could overcome both the T790 M mutations and exon 20 insertion of EGFR. YK-029A inhibited EGFR signaling, suppressed sensitive mutations and ex20ins of EGFR-driven cell proliferation, and was largely effective with oral administration in vivo. Furthermore, YK-029A exhibited significant antitumor activity in EGFRex20ins-driven patients-derived xenograft (PDX) models, preventing tumor progression or causing tumor regression at well-tolerated dosages. Based on the outcomes of preclinical efficacy and safety studies, YK-029A will enter phase Ⅲ clinical trials for the treatment of EGFRex20ins NSCLC.

Phase 1b trial of anti-EGFR antibody JMT101 and Osimertinib in EGFR exon 20 insertion-positive non-small-cell lung cancer

EGFR exon 20 insertion (20ins)-positive non-small-cell lung cancer (NSCLC) is an uncommon disease with limited therapeutic options and dismal prognosis. Here we report the activity, tolerability, potential mechanisms of response and resistance for dual targeting EGFR 20ins with JMT101 (anti-EGFR monoclonal antibody) plus osimertinib from preclinical models and an open label, multi-center phase 1b trial (NCT04448379). Primary endpoint of the trial is tolerability. Secondary endpoints include objective response rate, duration of response, disease control rate, progression free survival, overall survival, the pharmacokinetic profile of JMT101, occurrence of anti-drug antibodies and correlation between biomarkers and clinical outcomes. A total of 121 patients are enrolled to receive JMT101 plus osimertinib 160 mg. The most common adverse events are rash (76.9%) and diarrhea (63.6%). The confirmed objective response rate is 36.4%. Median progression-free survival is 8.2 months. Median duration of response is unreached. Subgroup analyses were performed by clinicopathological features and prior treatments. In patients with platinum-refractory diseases (n = 53), confirmed objective response rate is 34.0%, median progression-free survival is 9.2 months and median duration of response is 13.3 months. Responses are observed in distinct 20ins variants and intracranial lesions. Intracranial disease control rate is 87.5%. Confirmed intracranial objective response rate is 25%.

Overview on Therapeutic Options in Uncommon EGFR Mutant Non-Small Cell Lung Cancer (NSCLC): New Lights for an Unmet Medical Need

The majority of epidermal growth factor receptor (EGFR) mutations (85-90%) are exon 19 deletions and L858R point mutations of exon 21, characterized by high sensitivity to EGFR-tyrosine kinase inhibitors (TKIs). Less is known about uncommon mutations (10-15% of EGFR mutations). The predominant mutation types in this category include exon 18 point mutations, exon 21 L861X, exon 20 insertions, and exon 20 S768I. This group shows a heterogeneous prevalence, partly due to different testing methods and to the presence of compound mutations, which in some cases can lead to shorter overall survival and different sensitivity to different TKIs compared to simple mutations. Additionally, EGFR-TKI sensitivity may also vary depending on the specific mutation and the tertiary structure of the protein. The best strategy remains uncertain, and the data of EGFR-TKIs efficacy are based on few prospective and some retrospective series. Newer investigational agents are still under study, and there are no other approved specific treatments targeting uncommon EGFR mutations. Defining the best treatment option for this patient population remains an unmet medical need. The objective of this review is to evaluate existing data on the outcomes, epidemiology, and clinical characteristics of lung cancer patients with rare EGFR mutations, with a focus on intracranial activity and response to immunotherapy.

IL6 Mediates Suppression of T- and NK-cell Function in EMT-associated TKI-resistant EGFR-mutant NSCLC

PURPOSE

Patients with advanced non-small cell lung cancer (NSCLC) harboring activating EGFR mutations are initially responsive to tyrosine kinase inhibitors (TKI). However, therapeutic resistance eventually emerges, often via secondary EGFR mutations or EGFR-independent mechanisms such as epithelial-to-mesenchymal transition. Treatment options after EGFR-TKI resistance are limited as anti-PD-1/PD-L1 inhibitors typically display minimal benefit. Given that IL6 is associated with worse outcomes in patients with NSCLC, we investigate whether IL6 in part contributes to this immunosuppressed phenotype.

EXPERIMENTAL DESIGN

We utilized a syngeneic genetically engineered mouse model (GEMM) of EGFR-mutant NSCLC to investigate the effects of IL6 on the tumor microenvironment and the combined efficacy of IL6 inhibition and anti-PD-1 therapy. Corresponding in vitro studies used EGFR-mutant human cell lines and clinical specimens.

RESULTS

We identified that EGFR-mutant tumors which have oncogene-independent acquired resistance to EGFR-TKIs were more mesenchymal and had markedly enhanced IL6 secretion. In EGFR-mutant GEMMs, IL6 depletion enhanced activation of infiltrating natural killer (NK)- and T-cell subpopulations and decreased immunosuppressive regulatory T and Th17 cell populations. Inhibition of IL6 increased NK- and T cell-mediated killing of human osimertinib-resistant EGFR-mutant NSCLC tumor cells in cell culture. IL6 blockade sensitized EGFR-mutant GEMM tumors to PD-1 inhibitors through an increase in tumor-infiltrating IFNγ+ CD8+ T cells.

CONCLUSIONS

These data indicate that IL6 is upregulated in EGFR-mutant NSCLC tumors with acquired EGFR-TKI resistance and suppressed T- and NK-cell function. IL6 blockade enhanced antitumor immunity and efficacy of anti-PD-1 therapy warranting future clinical combinatorial investigations.

Rare molecular subtypes of lung cancer

Oncogenes that occur in ≤5% of non-small-cell lung cancers have been defined as 'rare'; nonetheless, this frequency can correspond to a substantial number of patients diagnosed annually. Within rare oncogenes, less commonly identified alterations (such as HRAS, NRAS, RIT1, ARAF, RAF1 and MAP2K1 mutations, or ERBB family, LTK and RASGRF1 fusions) can share certain structural or oncogenic features with more commonly recognized alterations (such as KRAS, BRAF, MET and ERBB family mutations, or ALK, RET and ROS1 fusions). Over the past 5 years, a surge in the identification of rare-oncogene-driven lung cancers has challenged the boundaries of traditional clinical grade diagnostic assays and profiling algorithms. In tandem, the number of approved targeted therapies for patients with rare molecular subtypes of lung cancer has risen dramatically. Rational drug design has iteratively improved the quality of small-molecule therapeutic agents and introduced a wave of antibody-based therapeutics, expanding the list of actionable de novo and resistance alterations in lung cancer. Getting additional molecularly tailored therapeutics approved for rare-oncogene-driven lung cancers in a larger range of countries will require ongoing stakeholder cooperation. Patient advocates, health-care agencies, investigators and companies with an interest in diagnostics, therapeutics and real-world evidence have already taken steps to surmount the challenges associated with research into low-frequency drivers.

New therapies in non-small cell lung cancer with EGFR exon 20 insertion mutations

OBJECTIVE

Patients with non-small cell lung cancer (NSCLC) and epidermal growth factor receptor (EGFR) exon 20 insertion mutations have a poor prognosis and few therapeutic alternatives. We conducted a review of scientific evidence about therapies in NSCLC with EGFR exon 20 insertion mutations.

DATA SOURCES

A systematic review in PubMed® database was performed up to November 19, 2022. Clinical trials (CTs) about treatments of patients diagnosed with advanced or metastatic NSCLC harbouring EGFR exon 20 insertions who had previously received platinum-based chemotherapy were selected. CTs with a sample size of less than 10 patients were discarded. Efficacy results were used to determine the most interesting drugs. Subsequently, a more exhaustive analysis of the design of the CTs and safety of the most interesting schemes was conducted. Comparisons were attempted to develop.

DATA SUMMARY

A total of 40 records were found in the systematic search. Twelve selected CTs included the following therapies: poziotinib, osimertinib, pertuzumab-trastuzumab-docetaxel scheme, mobocertinib, amivantamab, erlotinib-onalespib regimen, luminespib, ado-trastuzumab emtansine and dacomitinib. Mobocertinib, amivantamab and poziotinib were determined as the most interesting treatments according to efficacy data. Gastrointestinal and dermatological adverse reactions were relevant in these regimens. All CTs presented a non-randomised design. No reliable comparisons could be developed.

CONCLUSIONS

The efficacy of mobocertinib, amivantamab and poziotinib in NSCLC with EGFR exon 20 insertion mutations is promising. However, therapies were assessed in single-arm CTs with low-quality evidence. Comparative studies with more extensive patient follow-up, larger sample size and better design are needed to reliably quantify the effect of these drugs.

The EGFR C797S Mutation Confers Resistance to a Novel EGFR Inhibitor CLN-081 to EGFR Exon 20 Insertion Mutations

Introduction

EGFR exon 20 insertion mutations account for 5% to 10% of EGFR-mutated NSCLC. CLN-081 (formerly known as TAS6417), a novel covalent EGFR tyrosine kinase inhibitor, exhibits pan-mutation selective efficacy, including exon 20 insertions, in the clinical setting. Nevertheless, some patients may not respond to CLN-081 and resistance to CLN-081 may emerge over time in others.

Methods

We exposed Ba/F3 cells transduced with EGFR exon 20 insertions (Y764_V765 insHH or A767_S768insSVD) to increasing concentrations of CLN-081 to generate resistant cells and then subjected their complementary DNA to sequencing to identify acquired mutations. We then evaluated effects of small molecules on engineered Ba/F3 cells on the basis of proliferation assays, Western blotting, and xenograft models.

Results

All CLN-081 resistant clones harbored the EGFR C797S mutation. Ba/F3 cells with C797S (Ba/F3-C797S) were resistant to EGFR tyrosine kinase inhibitors targeting EGFR exon 20 insertion mutations, including CLN-081. Pimitespib, a selective heat shock protein 90 inhibitor, induced apoptosis in Ba/F3-C797S cells in vitro and inhibited growth of Ba/F3-C797S tumors in vivo. Ba/F3 cells with A763_Y764insFQEA-C797S remained sensitive to erlotinib.

Conclusions

We conclude that the EGFR C797S mutation confers resistance to CLN-081. Our preclinical data suggest a potential small molecule to overcome CLN-081 resistance, which may benefit patients with lung cancer with EGFR exon 20 insertions.

[Advances in the Treatment of EGFR Exon 20ins Mutant NSCLC]

Lung cancer has become one of the most dangerous cancers to human health and the mortality rate is the highest among all the causes of cancer death. Non-small cell lung cancer (NSCLC) accounts for about 80%-85% of lung cancer. Chemotherapy is the main treatment for advanced NSCLC, but the 5-year survival rate is low. Epidermal growth factor receptor (EGFR) mutations are the most common driver mutations in lung cancer, but EGFR exon 20 insertions (EGFR ex20ins) mutation belongs to one of the rare mutations, accounting for about 4%-10% of overall EGFR mutations, thus around 1.8% of advanced NSCLC patients. In recent years, targeted therapies represented by EGFR tyrosine kinase inhibitors (TKIs) have become an important treatment option for patients with advanced NSCLC, however, NSCLC patients with EGFR ex20ins mutation are not sensitive to most of EGFR-TKIs treatments. Currently, some of the targeted drugs for EGFR ex20ins mutation have achieved significant efficacy, while some of them are still under clinical investigation. In this article, we will describe various treatment methods for EGFR ex20ins mutation and their efficacy.
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[Progress in Detection of EGFR Exon 20 Insertion Mutation and Targeted Therapies in Non-small Cell Lung Cancer]

Epidermal growth factor receptor exon 20 insertion (EGFR ex20ins) is one of the earliest driver gene activation mutations in non-small cell lung cancer (NSCLC). However, due to the unique structure of protein variation caused by this mutation, most patients with EGFR ex20ins mutation (except A763_Y764insFQEA) have poor response to the launched first/second/third generation EGFR-tyrosine kinase inhibitors (EGFR-TKIs). With the successive approval of new specific targeted drugs for EGFR ex20ins in Food and Drug Administration (FDA) and other national regulatory agencies, the development and clinical research of targeted drugs for EGFR ex20ins in China have also developed rapidly and Mobocertinib has been approved recently in China. It is worth noting that EGFR ex20ins is a variant type with strong molecular heterogeneity. How to detect it comprehensively and accurately in clinical practice, so as to enable more patients to benefit from targeted therapy, is a very important and urgent problem to be solved. This review introduces the molecular typing of EGFR ex20ins, then discusses the importance of EGFR ex20ins detection and the differences of various detection methods, and summarizes the research and development of new drugs progress of EGFR ex20ins, in order to optimize the diagnosis and treatment path of EGFR ex20ins patients by selecting accurate, rapid and appropriate detection methods, so as to improve the clinical benefits of the patients.
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Advances in the management of non-small-cell lung cancer harbouring EGFR exon 20 insertion mutations

Epidermal growth factor receptor (EGFR) mutation is one of the key oncogenic mutations in non-small-cell lung cancer with adenocarcinoma histology. Exon 19 deletions and exon 21 L858R substitutions account for 90%, while EGFR exon 20 insertions constitute 4-10% of EGFR mutations and are the third most prevalent activating EGFR mutations. EGFR exon 20 insertions are associated with decreased sensitivity to EGFR tyrosine kinase inhibitors and, until recently, effective targeted therapy against these tumours remained an unmet clinical need and chemotherapy was the only treatment of choice available. The approval of amivantamab and mobocertinib for patients who have progressed after chemotherapy represents an important step forward in the management of these patients. Here in this review, we summarize the epidemiology, structure and the tumour microenvironment of EGFR exon 20 insertion and also review the systemic treatments, including targeted therapies and ongoing clinical trials in EGFR exon 20 insertion mutations, as well as detection methods for EGFR exon 20 insertion. Lastly, resistant mechanisms and future directions are addressed.

Structure-Guided Strategies of Targeted Therapies for Patients with EGFR-Mutant Non-Small Cell Lung Cancer

Oncogenic mutations within the EGFR kinase domain are well-established driver mutations in non-small cell lung cancer (NSCLC). Small-molecule tyrosine kinase inhibitors (TKIs) specifically targeting these mutations have improved treatment outcomes for patients with this subtype of NSCLC. The selectivity of these targeted agents is based on the location of the mutations within the exons of the EGFR gene, and grouping mutations based on structural similarities has proved a useful tool for conceptualizing the heterogeneity of TKI response. Structure-based analysis of EGFR mutations has influenced TKI development, and improved structural understanding will inform continued therapeutic development and further improve patient outcomes. In this review, we summarize recent progress on targeted therapy strategies for patients with EGFR-mutant NSCLC based on structure and function analysis.

Molecular Epidemiology and Treatment Patterns of Patients With EGFR Exon 20-Mutant NSCLC in the Precision Oncology Era: The European EXOTIC Registry

Introduction

Real-world evidence regarding molecular epidemiology and management patterns of patients with EGFR exon-20 mutated, advanced NSCLC outside the context of clinical trials is lacking.

Methods

We created a European registry for patients with advanced EGFR exon 20-mutant NSCLC diagnosed from January 2019 to December 2021. Patients enrolled in clinical trials were excluded. Clinicopathologic and molecular epidemiology data were collected, and treatment patterns were recorded. Clinical end points according to treatment assignment were assessed using Kaplan-Meier curves and Cox regression models.

Results

Data on 175 patients from 33 centers across nine countries were included in the final analysis. Median age was 64.0 (range: 29.7-87.8) years. Main features included female sex (56.3%), never or past smokers (76.0%), adenocarcinoma (95.4%), and tropism for bone (47.4%) and brain (32.0%) metastases. Mean programmed death-ligand 1 tumor proportional score was 15.8% (range: 0%-95%) and mean tumor mutational burden was 7.06 (range: 0-18.8) mutations per megabase. Exon 20 was detected in the tissue (90.7%), plasma (8.7%), or both (0.6%), using mostly targeted next-generation sequencing (64.0%) or polymerase chain reaction (26.0%). Mutations were mainly insertions (59.3%), followed by duplications (28.1%), deletions-insertions (7.7%), and the T790M (4.5%). Insertions and duplications were located mainly in the near loop (codons 767-771, 83.1%) and the far loop (codons 771-775, 13%) and only in 3.9% within the C helix (codons 761-766). Main co-alterations included mutations in TP53 (61.8%) and MET amplifications (9.4%). Treatment on mutation identification included chemotherapy (CT) (33.8%), CT-immunotherapy (IO) (18.2%), osimertinib (22.1%), poziotinib (9.1%), mobocertinib (6.5%), mono-IO (3.9%), and amivantamab (1.3%). Disease control rates were 66.2% with CT plus or minus IO, 55.8% with osimertinib, 64.8% with poziotinib, and 76.9% with mobocertinib. Corresponding median overall survival was 19.7, 15.9, 9.2, and 22.4 months, respectively. In multivariate analysis, type of treatment (new targeted agents versus CT ± IO) affected progression-free survival (p = 0.051) and overall survival (p = 0.03).

Conclusions

EXOTIC represents the largest academic real-world evidence data set on EGFR exon 20-mutant NSCLC in Europe. Indirectly compared, treatment with new exon 20-targeting agents is likely to confer survival benefit than CT plus or minus IO.

EGFR exon 20 insertion variants A763_Y764insFQEA and D770delinsGY confer favorable sensitivity to currently approved EGFR-specific tyrosine kinase inhibitors

Background: The EGFR exon 20 insertions (ex20ins) D770_N771insSVD and V769_D770insASV are most frequent in non-small-cell lung cancer (NSCLC) and are associated with intrinsic resistance to currently approved EGFR tyrosine kinase inhibitors (TKIs). A763_Y764insFQEA and D770delinsGY, respectively, account for 3%-8% and 2.0%-4.8% of EGFR ex20ins in NSCLC and are associated with a more favorable response to EGFR-specific TKIs as per case reports. The aim of this study was to elucidate the molecular structures of these mutants and their binding affinities to diverse EGFR TKIs and compare the clinical outcomes in NSCLC patients harboring these mutations. Methods: A real-world cohort study was conducted to evaluate and compare the clinical outcomes of EGFR TKIs among NSCLC patients with different EGFR ex20ins mutants in response to EGFR TKIs. The structures of A763_Y764insFQEA and D770delinsGY were also analyzed and drug binding simulations were performed. Results: With a median follow-up of 24.0 months, the first-line objective response rate (ORR), disease control rate (DCR), and median progression-free survival (PFS) were, respectively, 0 (0/16), 50.0% (8/16), and 2.07 months (95%CI, 0-6.25) in patients harboring D770_N771insSVD and V769_D770insASV variants and 33.3% (4/12), 83.3% (10/12), and 9.97 months (95%CI, 4.75-15.19) in patients with A763_Y764insFQEA and D770delinsGY variants. There was a significant difference between the PFS of these two subgroups (median, 9.97 vs.2.07 months, HR = 0.33, 95%CI, 0.13-0.85, p = 0.02). Similarly, the PFS was significantly longer after second-line treatment with EGFR TKIs in patients harboring A763_Y764insFQEA and D770delinsGY compared to those with other insertions (median, 6.77 vs.2.23 months, HR = 0.14, p < 0.001). Computational simulations indicated that A763_Y764insFQEA and D770delinsGY mutants were structurally similar to wild-type EGFR. In contrast, the C-helix and phosphate-binding loop of D770_N771insSVD and V769_D770insASV had shifted into the drug-binding pocket, resulting in significant steric hindrance and a lack of affinity for the currently approved EGFR inhibitors. Conclusion: NSCLC patients harboring A763_Y764insFQEA and D770delinsGY insertions of EGFR are responsive to the currently approved EGFR TKIs as opposed to patients with the D770_N771insSVD and V769_D770insASV variants. Therefore, A763_Y764insFQEA and D770delinsGY should be classified as active mutations among heterogeneous EGFR ex20ins subtypes and the carriers can be treated with the suitable EGFR TKIs.

Optimizing diagnosis and treatment of EGFR exon 20 insertions mutant NSCLC

The Epidermal growth factor receptor (EGFR) exon (ex) 20 insertions (ins) has been considered as an "undruggable target" for a long time, with platinum-pemetrexed combination recommended as upfront standard treatment for newly diagnosed advanced non-small cell lung cancer (NSCLC) patients. Recent preliminary data from early phase clinical trials have demonstrated that pharmacological inhibition of EGFRex20ins is possible, offering new treatment opportunities to 1-2% of advanced NSCLC patients harboring such hard-to-treat molecular alteration. Among the different drugs under clinical investigation, both amivantamab and mobocertinib have received regulatory approval in the United States, by the Food and Drugs Administration (FDA), while amivantamab has been recently approved also in Europe, for the clinical treatment of advanced NSCLC patients harboring EGFRex20ins who failed at least one prior line of systemic therapy, representing a major breakthrough in lung cancer treatment over the last year. With novel effective targeted options on the horizon, there is a renewed interest on optimizing the molecular screening of advanced NSCLC, and next-generation sequencing (NGS)-based genotyping is currently considered the gold standard approach to profile advanced NSCLC patients, as recommended by international guidelines. Herein we provide an updated overview of the most recent findings and upcoming challenges regarding both molecular detection and therapeutic management of EGFR ex20ins mutant advanced NSCLC patients.

Location of EGFR exon 20 insertions matters

EGFR exon 20 insertions represent a subgroup of NSCLC patients posed with a therapy dilemma. In this issue of Cancer Cell, Elamin and colleagues demonstrate that only insertions localized in the near loop respond to poziotinib. Pharmacological inhibition of spindle assembly checkpoint components inhibits tumor growth in poziotinib-resistant exon 20 insertions.