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

Genomic and clinical characterization of HER2 exon 20 mutations in non-small cell lung cancer: insights from a multicenter study in South China

BACKGROUND

The objective of this study was to investigate the clinical and genetic characteristics and clinical relevance of HER2 exon 20 oncogenic variants in non-small cell lung cancer (NSCLC) patients.

METHODS

This prospective study analyzed 51 NSCLC patients with HER2 mutations, identified via next-generation sequencing (NGS) of tissue, blood, cerebrospinal fluid, or pleural effusion samples. Patients were grouped based on the presence of exon 20 mutations (exon 20 vs. non-exon 20) and further divided based on whether they had received prior anti-tumor treatments (baseline vs. non-baseline). Clinical and genetic data, treatment responses were analyzed. Progression-free survival (PFS) and overall survival (OS) were evaluated using Kaplan-Meier methods and compared with log-rank tests. Gene ontology (GO) analysis was performed to uncover the biological significance of the mutated genes.

RESULTS

In a cohort of 651 NSCLC patients, 51 (7.83%) harbored HER2 alterations, including 20 (3.08%) with exon 20 mutations. The median age of the HER2-altered subgroup was 58.5 years. Adenocarcinoma was the most prevalent subtype (96.1%), and most patients presented at stage IV (72.5%). The most common metastatic sites were the lungs (68.6%), lymph nodes (52.9%), and brain (43.1%). Among the HER2 mutated patients, 20 (39.3%) had exon 20 mutations. Exon 20 mutations were more prevalent in the non-baseline group (55.0% vs. 29.0%, P = 0.049) and males (75.0%, P = 0.025). These mutations were associated with a higher rate of metastasis to the lungs, lymph nodes (P < 0.001). Patients with exon 20 mutations demonstrated poorer overall survival (OS) outcomes (P = 0.048). No significant differences were observed in age, smoking history, histological subtype, or TNM stage at diagnosis between groups. The majority of exon 20 mutations were in-frame indel mutations (92.0%), with the most common specific mutation being p.Y772_A775dup (70%). Gene Ontology (GO) analysis linked exon 20 mutations to unregulated protein kinase activity and anoikis.

CONCLUSIONS

Our study found that NSCLC patients with HER2 exon 20 oncogenic variants have a higher risk of metastasis and drug resistance, leading to worse outcomes than non-exon 20 mutations. This highlights the urgent need for targeted therapies aimed at exon 20 insertions to improve survival and treatment outcomes in this subgroup.

Patterns of HER2 expression and genomic correlates in lung cancer, with a focus on preanalytical variables impacting immunohistochemical staining results

AIMS

Fam-trastuzumab deruxtecan-nxki (T-DXd) was recently approved for advanced stage or metastatic solid tumours with human epidermal growth factor receptor 2 (HER2) immunohistochemical (IHC) 3+ staining. Data on HER2 IHC testing and knowledge of genomic correlates in lung cancer are scarce. This study analyses genomic characteristics of HER2-expressing tumours and addresses issues with preanalytical variables for lung cancer specimens.

METHODS

HER2 IHC staining was performed on selected archival cytology and surgical pathology lung cancer specimens for patients eligible for T-DXd therapy. Patient and tumour characteristics and next-generation sequencing (NGS) data were correlated with HER2 IHC results.

RESULTS

166 patients with thoracic tumour samples had HER2 expression assessed: 46% were IHC 0, 28% IHC 1+, 13% IHC 2+ and 13% IHC 3+. HER2 IHC scores were overall lower for cytology cell blocks as compared with surgical pathology specimens; 79% of cases with paired specimens had a decrease in their HER2 IHC score from their surgical specimen to their paired cytology specimen. Of specimens with HER2 IHC 3+ and NGS available, only 14% (3/21) had concomitant ERBB2 alterations. Among all specimens, ERBB2 point mutations were noted in 4% (4/110) and ERBB2 amplification in 3% (3/110). The majority of HER2 3+ cases with paired NGS (17/21, 81%) had non-ERBB2 genomic alterations, including: KRAS, TP53, and STK11 mutations.

CONCLUSIONS

HER2 IHC 3+ is seen in a small but clinically significant proportion of samples and is associated with a variety of co-occurring non-ERBB2 genomic alterations. Preanalytical variables including specimen fixation can significantly impact the assessment of HER2 expression via immunohistochemistry.

Erratum to 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

[This corrects the article DOI: 10.21037/tlcr-23-98.].

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.

First case report of sunvozertinib for the treatment of HER2 exon 20 insertion in lung adenocarcinoma

Human epidermal growth factor receptor 2 (HER2) is a transmembrane glycoprotein receptor with intracellular tyrosine kinase activity. It is generally considered as a poor prognostic marker. Targeted therapies, such as small molecule tyrosine kinase inhibitors (TKIs), showed limited efficacy in HER2-mutant advanced nonsmall cell lung cancer (NSCLC). In the 2023 National Comprehensive Cancer Network guidelines for NSCLC, antibody-drug conjugate trastuzumab emtansine is recommended for the treatment of HER2-mutant lung cancer. However, this medication is currently not approved in certain regions. So it is necessary to explore alternative treatment options for HER2-mutant NSCLC patients. In our study of a patient with HER2 exon 20 insertion lung adenocarcinoma who had previously failed multiple epidermal growth factor receptor (EGFR)-TKI treatments, we discovered that sunvozertinib could stabilize the patient's condition, achieving a progression-free survival of 87 days. This is a novel finding that may provide new treatment options for HER2 exon 20 insertion patients who have failed TKI therapy.

Peptidyl-prolyl isomerase F as a prognostic biomarker associated with immune infiltrates and mitophagy in lung adenocarcinoma

Background

Lung adenocarcinoma (LUAD) is among the most prevalent malignancies worldwide, with unfavorable treatment outcomes. Peptidyl-prolyl isomerase F (PPIF) is known to influence the malignancy traits of tumor progression by modulating the bioenergetics and mitochondrial permeability in cancer cells; however, its role in LUAD remains unclear. Our study seeks to investigate the clinical significance, tumor proliferation, and immune regulatory functions of PPIF in LUAD.

Methods

The expression of PPIF in LUAD tissues and cells was assessed using bioinformatics analysis, immunohistochemistry (IHC), and Western blotting. Survival curve analysis was conducted to examine the prognostic association between PPIF expression and LUAD. The immunomodulatory role of PPIF in LUAD was assessed through the analysis of PPIF expression and immune cell infiltration. A series of gain- and loss-of-function experiments were conducted on PPIF to investigate its biological functions in LUAD both in vitro and in vivo. The mechanisms underlying PPIF's effects on LUAD were delineated through functional enrichment analysis and Western blotting assays.

Results

PPIF exhibited overexpression in LUAD tissues compared to normal controls. Survival curve analysis revealed that patients with LUAD exhibiting higher PPIF expression demonstrated decreased overall survival and a shorter progression-free interval. PPIF was implicated in modulating immune cell infiltration, particularly in regulating the T helper 1-T helper 2 cell balance. Functionally, PPIF was discovered to promote tumor cell proliferation and advance cell-cycle progression. Furthermore, PPIF could impede mitophagy by targeting the FOXO3a/PINK1-Parkin signaling pathway.

Conclusions

The findings of this study indicate that the prognosis-related gene PPIF may have a significant role in the regulation of LUAD cell proliferation, tumor-associated immune cell infiltration, and mitophagy, and thus PPIF may be a promising therapeutic target of LUAD.

Current status of molecular diagnostics for lung cancer

The management of lung cancer (LC) requires the analysis of a diverse spectrum of molecular targets, including kinase activating mutations in EGFR, ERBB2 (HER2), BRAF and MET oncogenes, KRAS G12C substitutions, and ALK, ROS1, RET and NTRK1-3 gene fusions. Administration of immune checkpoint inhibitors (ICIs) is based on the immunohistochemical (IHC) analysis of PD-L1 expression and determination of tumor mutation burden (TMB). Clinical characteristics of the patients, particularly age, gender and smoking history, significantly influence the probability of finding the above targets: for example, LC in young patients is characterized by high frequency of kinase gene rearrangements, while heavy smokers often have KRAS G12C mutations and/or high TMB. Proper selection of first-line therapy influences overall treatment outcomes, therefore, the majority of these tests need to be completed within no more than 10 working days. Activating events in MAPK signaling pathway are mutually exclusive, hence, fast single-gene testing remains an option for some laboratories. RNA next-generation sequencing (NGS) is capable of detecting the entire repertoire of druggable gene alterations, therefore it is gradually becoming a dominating technology in LC molecular diagnosis.

The rapidly changing field of predictive biomarkers of non-small cell lung cancer

Lung cancer is a leading cause of cancer-related death worldwide in both men and women, however mortality in the US and EU are recently declining in parallel with the gradual cut of smoking prevalence. Consequently, the relative frequency of adenocarcinoma increased while that of squamous and small cell carcinomas declined. During the last two decades a plethora of targeted drug therapies have appeared for the treatment of metastasizing non-small cell lung carcinomas (NSCLC). Personalized oncology aims to precisely match patients to treatments with the highest potential of success. Extensive research is done to introduce biomarkers which can predict the effectiveness of a specific targeted therapeutic approach. The EGFR signaling pathway includes several sufficient targets for the treatment of human cancers including NSCLC. Lung adenocarcinoma may harbor both activating and resistance mutations of the EGFR gene, and further, mutations of KRAS and BRAF oncogenes. Less frequent but targetable genetic alterations include ALK, ROS1, RET gene rearrangements, and various alterations of MET proto-oncogene. In addition, the importance of anti-tumor immunity and of tumor microenvironment has become evident recently. Accumulation of mutations generally trigger tumor specific immune defense, but immune protection may be upregulated as an aggressive feature. The blockade of immune checkpoints results in potential reactivation of tumor cell killing and induces significant tumor regression in various tumor types, such as lung carcinoma. Therapeutic responses to anti PD1-PD-L1 treatment may correlate with the expression of PD-L1 by tumor cells. Due to the wide range of diagnostic and predictive features in lung cancer a plenty of tests are required from a single small biopsy or cytology specimen, which is challenged by major issues of sample quantity and quality. Thus, the efficacy of biomarker testing should be warranted by standardized policy and optimal material usage. In this review we aim to discuss major targeted therapy-related biomarkers in NSCLC and testing possibilities comprehensively.

Dacomitinib exhibits promising activity against the rare HER2 exon 20 insertion M774delinsWLV in lung cancer: A case report and literature review

A775_G776insYVMA, the typical and predominant HER2 exon 20 insertion variant in non-small cell lung cancer, exhibits relative insensitivity to covalent HER2-targeted tyrosine kinase inhibitors. However, other less common insertions have shown better responses to HER2-targeted inhibitors. M774delinsWLV is a rare HER2 exon 20 insertion subtype and its clinical sensitivity to HER2-targeted inhibitors remains unclear. Furthermore, there is a lack of current studies to elucidate its structure and predict its sensitivity to HER2-targeted tyrosine kinase inhibitors. Herein, we presented a case of non-small cell lung cancer harboring M774delinsWLV who derived favorable response and significant survival benefit from HER2-targeted tyrosine kinase inhibitors. A 60-year-old male with metastatic lung adenocarcinoma carrying M774delinsWLV received pyrotinib monotherapy as first-line treatment. After rapid disease progression at three months, sequential combination therapy with pyrotinib and bevacizumab yielded promising antitumor activity and sustained progression-free survival benefits for nearly a year. Subsequent dacomitinib monotherapy displayed significant activity against this uncommon insertion, resulting in a rapid decrease in tumor markers and partial response, along with progression-free survival of one year. The molecular simulation revealed no significant differences in the overall protein structure and binding pocket region between M774delinsWLV and the HER2 wild type. Drug binding dynamics simulation indicated that dacomitinib exhibited the most potent binding activity compared to afatinib, pyrotinib and poziotinib. Conclusively, dacomitinib exhibited promising efficacy against the rare HER2 exon 20 insertion M774delinsWLV. Extensive investigation is needed to elucidate the effects of HER2-targeted tyrosine kinase inhibitors on non-small cell lung cancer with different HER2 insertion subtypes.

First-in-human phase I study of BEBT-109 in previously treated EGFR exon 20 insertion-mutated advanced non-small cell lung cancer

BACKGROUND

BEBT-109 is an oral pan-mutant-selective inhibitor of epidermal growth factor receptor (EGFR) that demonstrated promising antitumor potency in preclinical models.

METHODS

This first-in-human study was a single-arm, open-label, two-stage study. Phase Ia dose-escalation study evaluated the safety and pharmacokinetics of BEBT-109 in 11 patients with EGFR T790M-mutated advanced non-small cell lung cancer (aNSCLC). Phase Ib dose-expansion study evaluated the safety and efficacy of BEBT-109 in 18 patients with EGFR exon 20 insertion (ex20ins)-mutated treatment-refractory aNSCLC. The primary outcomes were adverse events and antitumor activity. Clinical trial registration number CTR20192575.

FINDINGS

The phase Ia study demonstrated no dose-limiting toxicity, no observation of the maximum tolerated dose, and no new safety signals with BEBT-109 in the dose range of 20-180 mg/d, suggesting that BEBT-109 had an acceptable safety profile among patients with EGFR T790M-mutated aNSCLC. Plasma pharmacokinetics of BEBT-109 showed a dose-proportional increase in the area under the curve and maximal concentration, with no significant drug accumulation. The dose-expansion study demonstrated that BEBT-109 treatment was tolerable across the three dose levels. The three most common treatment-related adverse events were diarrhea (100%; 22.2% ≥Grade 3), rash (66.7%; 5.6% ≥Grade 3), and anemia (61.1%; 0% ≥Grade 3). The objective response rate was 44.4% (8 of 18). Median progression-free survival was 8.0 months (95% confidence intervals, 1.33-14.67).

CONCLUSION

Preliminary findings showed that BEBT-109 had an acceptable safety profile and favorable antitumor activity in patients with refractory EGFR ex20ins-mutated aNSCLC.

FUNDING

National Natural Science Foundation of China.

Current status and breakthroughs in treating advanced non-small cell lung cancer with EGFR exon 20 insertion mutations

Recently, targeted therapy and immunotherapy have emerged as effective treatment options for non-small cell lung cancer (NSCLC). This progress has been facilitated by the rapid development of diagnostic and therapeutic technologies and the continuous research and development of new drugs, leading to a new era in precision medicine for NSCLC. This is a breakthrough for patients with common mutations in the human epidermal growth factor receptor (EGFR) gene in NSCLC. Consequently, the use of targeted drugs has significantly improved survival. Nevertheless, certain rare genetic mutations are referred to as EGFR exon 20 insertion (ex20ins) mutations, which differ in structure from conventional EGFR gene mutations, namely, exon 19 deletion mutations (19-Del) and exon 21 point mutations. Owing to their distinct structural characteristics, patients harboring these EGFR ex20ins mutations are unresponsive to traditional tyrosine kinase inhibitor (TKI) therapy. This particular group of patients did not fall within the scope of their applicability. However, the activating A763_Y764insFQEA mutation elicits a more pronounced response than mutations in the near and far regions of the C-helix immediately following it and should, therefore, be treated differently. Currently, there is a lack of effective treatments for EGFR ex20ins mutations NSCLC. The efficacy of chemotherapy has been relatively favorable, whereas the effectiveness of immunotherapy remains ambiguous owing to inadequate clinical data. In addition, the efficacy of the first- and second-generation targeted drugs remains limited. However, third-generation and novel targeted drugs have proven to be effective. Although novel EGFR-TKIs are expected to treat EGFR ex20ins mutations in patients with NSCLC, they face many challenges. The main focus of this review is on emerging therapies that target NSCLC with EGFR ex20ins and highlight major ongoing clinical trials while also providing an overview of the associated challenges and research advancements in this area.

Amivantamab: A Novel Advance in the Treatment of Non-small Cell Lung Cancer

Amivantamab is a fully human bispecific monoclonal antibody indicated for treating patients with specifically large cell lung cancer. Its dosage is based on the patient's initial body weight and is administered via intravenous infusion after dilution. Therefore, this drug is given as a strategy due to the great need for a molecule targeting epidermal growth factor receptor (EGFR) and the mesenchymal-epithelial transition factor (MET), as acquired resistance to tyrosine kinase inhibitors (TKIs) was observed in the treatment of large cell lung cancer. This article encompasses a review of the benefits of amivantamab for patients with non-small cell lung cancer (NSCLC). This drug is the first therapy directed against this specific mutation, and unlike others, it could bind to two genetic receptors, whereas antibodies, in general, are directed toward a single receptor.

The Impact of On-Target Resistance Mediated by EGFR-T790M or EGFR-C797S on EGFR Exon 20 Insertion Mutation Active Tyrosine Kinase Inhibitors

Introduction

Mechanisms of resistance to EGFR exon 20 insertion mutation active inhibitors have not been extensively studied in either robust preclinical models or patient-derived rebiopsy specimens. We sought to characterize on-target resistance mutations identified in EGFR exon 20 insertion-mutated lung cancers treated with mobocertinib or poziotinib and evaluate whether these mutations would or would not have cross-resistance to next-generation inhibitors zipalertinib, furmonertinib, and sunvozertinib.

Methods

We identified mechanisms of resistance to EGFR exon 20 insertion mutation active inhibitors and then used preclinical models of EGFR exon 20 insertion mutations (A767_V769dupASV, D770_N771insSVD, V773_C774insH) plus common EGFR mutants to probe inhibitors in the absence/presence of EGFR-T790M or EGFR-C797S.

Results

Mobocertinib had a favorable therapeutic window in relation to EGFR wild type for EGFR exon 20 insertion mutants, but the addition of EGFR-T790M or EGFR-C797S negated the observed window. Zipalertinib had a favorable therapeutic window for cells driven by EGFR-A767_V769dupASV or EGFR-D770_N771insSVD in the presence or absence of EGFR-T790M. Furmonertinib and sunvozertinib had the most favorable therapeutic windows in the presence or absence of EGFR-T790M in all cells tested. EGFR-C797S in cis to all EGFR mutations evaluated generated dependent cells that were resistant to the covalent EGFR tyrosine kinase inhibitors mobocertinib, zipalertinib, furmonertinib, sunvozertinib, poziotinib, and osimertinib.

Conclusions

This report highlights that poziotinib and mobocertinib are susceptible to on-target resistance mediated by EGFR-T790M or -C797S in the background of the most prevalent EGFR exon 20 insertion mutations. Furmonertinib, sunvozertinib, and to a less extent zipalertinib can overcome EGFR-T790M compound mutants, whereas EGFR-C797S leads to covalent inhibitor cross-resistance-robust data that support the limitations of mobocertinib and should further spawn the development of next-generation covalent and reversible EGFR exon 20 insertion mutation active inhibitors with favorable therapeutic windows that are less vulnerable to on-target resistance.

Management of HER2 alterations in non-small cell lung cancer - The past, present, and future

HER2 mutations, which account for 2-4% of non-small cell lung cancer (NSCLC), are distinct molecular alterations identified via next generation sequencing (NGS). Previously, treatment outcomes in HER2-mutant metastatic NSCLC were dismal, showing limited clinical benefit with platinum-based chemotherapy with or without immunotherapy. In contrast to HER2-altered breast and gastric cancer, HER2-mutant NSCLC does not benefit from HER2 targeting agents such as trastuzumab or TDM1. HER2 mutations are also inherently different from HER2 overexpression and amplification. Currently, trastuzumab deruxtecan, a HER2 targeting antibody drug conjugate (ADC) is the first and only approved treatment option for patients with HER2-mutant metastatic NSCLC after failure with standard treatment. In this review, we summarized the biology of HER2 and detection of HER2 overexpression, amplification and mutations, as well as general landscape of landmark and ongoing clinical trials encompassing from chemotherapy to targeted agents, including tyrosine kinase inhibitors (TKIs), ADCs and investigational agents.