Lung Adenocarcinoma Harboring EGFR T790M and In Trans C797S Responds to Combination Therapy of First- and Third-Generation EGFR TKIs and Shifts Allelic Configuration at Resistance

Mechanisms of resistance to tyrosine kinase inhibitor-targeted therapy and overcoming strategies

Tyrosine kinase inhibitor (TKI)-targeted therapy has revolutionized cancer treatment by selectively blocking specific signaling pathways crucial for tumor growth, offering improved outcomes with fewer side effects compared with conventional chemotherapy. However, despite their initial effectiveness, resistance to TKIs remains a significant challenge in clinical practice. Understanding the mechanisms underlying TKI resistance is paramount for improving patient outcomes and developing more effective treatment strategies. In this review, we explored various mechanisms contributing to TKI resistance, including on-target mechanisms and off-target mechanisms, as well as changes in the tumor histology and tumor microenvironment (intrinsic mechanisms). Additionally, we summarized current therapeutic approaches aiming at circumventing TKI resistance, including the development of next-generation TKIs and combination therapies. We also discussed emerging strategies such as the use of dual-targeted antibodies and PROteolysis Targeting Chimeras. Furthermore, we explored future directions in TKI-targeted therapy, including the methods for detecting and monitoring drug resistance during treatment, identification of novel targets, exploration of dual-acting kinase inhibitors, application of nanotechnologies in targeted therapy, and so on. Overall, this review provides a comprehensive overview of the challenges and opportunities in TKI-targeted therapy, aiming to advance our understanding of resistance mechanisms and guide the development of more effective therapeutic approaches in cancer treatment.

The efficacy of almonertinib and anlotinib combination therapy for advanced non-small-cell lung cancer patients who continued to experience cancer progression during third-generation EGFR-TKI treatment: a retrospective study

BACKGROUND

Epidermal growth factor receptor (EGFR) mutations are key drivers in a significant portion of non-small-cell lung cancer (NSCLC) patients. While third-generation EGFR-tyrosine kinase inhibitors (TKIs) such as osimertinib have demonstrated efficacy, the management of patients who continue to experience disease progression during treatment remains challenging. The emergence of drug resistance, including the development of secondary mutations, necessitates exploration of alternative treatment strategies. This study aims to evaluate and observe the efficacy and safety of almonertinib combined with anlotinib in patients after cancer progression during third-generation EGFR-TKI therapy.

METHODS

In this retrospective analysis, we included EGFR-mutated NSCLC patients who were resistant to third-generation EGFR-TKIs. All patients were treated with almonertinib combined with anlotinib. The clinical characteristics, treatment history, clinical benefits, and adverse events of these patients were retrospectively collected.

RESULTS

A total of 16 eligible patients were included in the analysis. The results revealed that combination therapy with almonertinib and anlotinib was effective in this patient cohort. The overall response rate was 25% and the disease control rate was 93.75%. The 6 and 12 months of PFS rates were 92.9% (95% confidence interval [CI] 80.3%, 100.0%) and 84.4% (95% CI 66.6%, 100.0%), respectively. Moreover, this combination therapy was generally well-tolerated, with manageable adverse events.

CONCLUSION

Our retrospective analysis suggests that almonertinib and anlotinib combination therapy may represent a viable option for EGFR-mutated NSCLC patients who have progressed on third-generation EGFR-TKIs, especially for those with posterior lines and no standard treatment options. Further investigation and larger clinical trials are warranted to validate these observations and refine treatment guidelines.

Liquid biopsy for the management of NSCLC patients under osimertinib treatment

Therapeutic management of NSCLC patients is quite challenging as they are mainly diagnosed at a late stage of disease, and they present a high heterogeneous molecular profile. Osimertinib changed the paradigm shift in treatment of EGFR mutant NSCLC patients achieving significantly better clinical outcomes. To date, osimertinib is successfully administered not only as first- or second-line treatment, but also as adjuvant treatment while its efficacy is currently investigated during neoadjuvant treatment or in stage III, unresectable EGFR mutant NSCLC patients. However, resistance to osimertinib may occur due to clonal evolution, under the pressure of the targeted therapy. The utilization of liquid biopsy as a minimally invasive tool provides insight into molecular heterogeneity of tumor clonal evolution and potent resistance mechanisms which may help to develop more suitable therapeutic approaches. Longitudinal monitoring of NSCLC patients through ctDNA or CTC analysis could reveal valuable information about clinical outcomes during osimertinib treatment. Therefore, several guidelines suggest that liquid biopsy in addition to tissue biopsy should be considered as a standard of care in the advanced NSCLC setting. This practice could significantly increase the number of NSCLC patients that will eventually benefit from targeted therapies, such as EGFR TKIs.

Furmonertinib and intrathecal pemetrexed chemotherapy rechallenges osimertinib-refractory leptomeningeal metastasis in a non-small cell lung cancer patient harboring EGFR20 R776S, C797S, and EGFR21 L858R compound EGFR mutations: a case report

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are considered the first-line treatment for advanced or metastatic non-small cell lung cancer (NSCLC) patients harboring EGFR mutations. However, due to the rarity of cases, the response of EGFR-TKIs in patients harboring uncommon compound EGFR mutations still needs to be determined. Here, we demonstrated the case of a 47-year-old smoker diagnosed with leptomeningeal metastasis from NSCLC and had EGFR20 R776S, C797S, and EGFR21 L858R compound mutations. He was treated with furmonertinib combined with intrathecal pemetrexed chemotherapy following progression on osimertinib, which led to clinical improvement and successfully prolonged his survival by 3 months. Regrettably, the patient eventually died from heart disease. This report provides the first reported evidence for the use of furmonertinib and intrathecal pemetrexed chemotherapy in NSCLC patients harboring EGFR R776S/C797S/L858R mutations who progressed on previous EGFR-TKIs.

Tyrosine kinase inhibitors in cancers: Treatment optimization - Part I

A multitude of TKI has been developed and approved targeting various oncogenetic alterations. While these have provided improvements in efficacy compared with conventional chemotherapies, resistance to targeted therapies occurs. Mutations in the kinase domain result in the inability of TKI to inactivate the protein kinase. Also, gene amplification, increased protein expression and downstream activation or bypassing of signalling pathways are commonly reported mechanisms of resistance. Improved understanding of mechanisms involved in TKI resistance has resulted in the development of new generations of targeted agents. In a race against time, the search for new, more potent and efficient drugs, and/or combinations of drugs, remains necessary as new resistance mechanisms to the latest generation of TKI emerge. This review examines the various generations of TKI approved to date and their common mechanisms of resistance, focusing on TKI targeting BCR-ABL, epidermal growth factor receptor, anaplastic lymphoma kinase and BRAF/MEK tyrosine kinases.

Custom-Designed Probes for the Accurate Determination of Epidermal Growth Factor Receptor Mutations and Their Allelic Configuration

The identification of single nucleotide polymorphisms (SNPs) is of paramount importance for disease diagnosis and clinical prognostication. In the context of nonsmall cell lung cancer (NSCLC), the emergence of resistance mutations, exemplified by the epidermal growth factor receptor (EGFR) T790 M and C797S, is intricately linked to the therapeutic efficacy of EGFR tyrosine kinase inhibitors (EGFR-TKIs). Herein, a highly efficient and specific SNP detection platform for T790 M and C797S mutations has been engineered through the integration of an asymmetric polymerase chain reaction (PCR) and an ingeniously tailored four-way junction (4WJ) probe. Notably, a molecular beacon (MB) probe was judiciously designed to discern the allelic configuration of these mutations. The administration of first- and third-generation EGFR-TKIs demonstrates therapeutic efficacy solely when the mutations are in the trans configuration, characterized by a low fluorescence signal. In contrast, significant fluorescence by the MB probe is indicative of the C797S mutation being in a cis arrangement with T790M, thereby rendering the cells refractory to the therapeutic interventions of both first- and third-generation EGFR-TKIs. The assay is capable of concurrently detecting two point-mutations and ascertaining their allelic positions in a single test within 1.5 h, enhancing both efficiency and simplicity. It also exhibits high accuracy in the identification of clinical samples, offering promising implications for therapeutic guidelines. By enabling tailored treatment plans based on specific genetic profiles, our approach not only advances the precision of NSCLC treatment strategies but also marks a significant contribution to personalized medicine.

Case report: Sustained remission after combined sintilimab, anti-VEGF therapy, and chemotherapy in a patient with non-small cell lung cancer harboring acquired EGFR 19Del/T790M/cis-C797S mutation resistance

Third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are highly effective against tumors harboring the T790M mutation. However, patients treated with these inhibitors ultimately develop resistance, and the most common mechanism is the emergence of the EGFR C797S mutation. Few treatment regimens have been reported for this condition. In this report, we present a successful combination treatment with the programmed cell death 1 (PD-1) inhibitor sintilimab, anti-vascular endothelial growth factor (VEGF) therapy, and chemotherapy with pemetrexed and cisplatin in a patient with non-small cell lung cancer (NSCLC) who developed acquired resistance with EGFR 19 exon deletion (19Del)/T790M/cis-C797S mutation following progression with ametinib therapy. This regimen was well tolerated, and the patient has remained progression-free for 15 months. Our case provides clinical evidence that the combination of PD-1 inhibitor, anti-VEGF therapy, and chemotherapy may be an efficacious therapeutic strategy for NSCLC patients with acquired EGFR 19Del/T790M/cis-C797S mutation resistance following progression with EGFR TKI therapy.

Plasma EBV quantification is associated with the efficacy of immune checkpoint blockade and disease monitoring in patients with primary pulmonary lymphoepithelioma-like carcinoma

Objectives

Primary pulmonary lymphoepithelioma-like carcinoma (PLELC) is a subtype of lung carcinoma associated with the Epstein-Barr virus (EBV). The clinical predictive biomarkers of immune checkpoint blockade (ICB) in PLELC require further investigation.

Methods

We prospectively analysed EBV levels in the blood and immune tumor biomarkers of 31 patients with ICB-treated PLELC. Viral EBNA-1 and BamHI-W DNA fragments in the plasma were quantified in parallel using quantitative polymerase chain reaction.

Results

Progression-free survival (PFS) was significantly longer in EBNA-1 high or BamHI-W high groups. A longer PFS was also observed in patients with both high plasma EBNA-1 or BamHI-W and PD-L1 ≥ 1%. Intriguingly, the tumor mutational burden was inversely correlated with EBNA-1 and BamHI-W. Plasma EBV load was negatively associated with intratumoral CD8+ immune cell infiltration. Dynamic changes in plasma EBV DNA level were in accordance with the changes in tumor volume. An increase in EBV DNA levels during treatment indicated molecular progression that preceded the imaging progression by several months.

Conclusions

Plasma EBV DNA could be a useful and easy-to-use biomarker for predicting the clinical activity of ICB in PLELC and could serve to monitor disease progression earlier than computed tomography imaging.

Insights into the Overcoming EGFRDel19/T790M/C797S Mutation: A Perspective on the 2-Aryl-4-aminothienopyrimidine Backbone

The epithelial growth factor receptor (EGFR) signaling pathway has been proposed to benefit non-small cell lung cancer (NSCLC) treatment. In this manuscript, we investigated the modification of 2-aryl-4-aminoquinazoline, the classical backbone of the fourth-generation EGFR inhibitors, in addition to obtaining a series of novel 2-aryl-4-aminothienopyrimidine derivatives (A1~A45), we also gained further understanding of the modification of this framework. Derivatives were tested for cytotoxicity against cancer cell lines (cervical cancer cell line Hela, lung cancer cell lines A549, H1975, and PC-9, Ba/F3-EGFRDel19/T790M/C797S cells, and human normal hepatocytes LO2) as well as for the derivative's inhibitory activity against EGFRWT, EGFRL858R/T790M, and EGFRDel19/T790M/C797S kinase inhibitory activities. The results showed that most of the target compounds showed moderate to excellent activity against one or more cancer cell lines. Among them, the antitumor activity (IC50) of the most promising A9 against A549 and H1975 cell lines was 0.77±0.08 μM, 6.90±0.83 μM, respectively. At concentration of 10 μM, A9 can be employed as the fourth-generation of EGFR inhibitors with the ability to overcome the C797S drug resistance since it can suppress EGFRDel19/T790M/C797S cells and kinase by 98.90 % and 85.88 %, respectively. Moreover, the tumor-bearing nude mice experiment further shows that A9 can significantly inhibit the growth of tumor in vivo, with the tumor inhibition rate (TIR) of 55.92 %, which was equivalent to the positive group. After that, from the result of HE staining experiment and blood biochemical analysis experiment, A9 show low toxicity and good safety, which is worthy of further research and development.

Discovery of a Novel Potent EGFR Inhibitor Against EGFR Activating Mutations and On-Target Resistance in NSCLC

PURPOSE

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) serve as the standard first-line therapy for EGFR-mutated non-small cell lung cancer (NSCLC). Despite the sustained clinical benefits achieved through optimal EGFR-TKI treatments, including the third-generation EGFR-TKI osimertinib, resistance inevitably develops. Currently, there are no targeted therapeutic options available postprogression on osimertinib. Here, we assessed the preclinical efficacy of BI-4732, a novel fourth-generation EGFR-TKI, using patient-derived preclinical models reflecting various clinical scenarios.

EXPERIMENTAL DESIGN

The antitumor activity of BI-4732 was evaluated using Ba/F3 cells and patient-derived cell/organoid/xenograft models with diverse EGFR mutations. Intracranial antitumor activity of BI-4732 was evaluated in a brain-metastasis mouse model.

RESULTS

We demonstrated the remarkable antitumor efficacy of BI-4732 as a single agent in various patient-derived models with EGFR_C797S-mediated osimertinib resistance. Moreover, BI-4732 exhibited activity comparable to osimertinib in inhibiting EGFR-activating (E19del and L858R) and T790M mutations. In a combination treatment strategy with osimertinib, BI-4732 exhibited a synergistic effect at significantly lower concentrations than those used in monotherapy. Importantly, BI-4732 displayed potent antitumor activity in an intracranial model, with low efflux at the blood-brain barrier.

CONCLUSIONS

Our findings highlight the potential of BI-4732, a selective EGFR-TKI with high blood-brain barrier penetration, targeting a broad range of EGFR mutations, including C797S, warranting clinical development.

Mechanisms of resistance to targeted therapy and immunotherapy in non-small cell lung cancer: promising strategies to overcoming challenges

Resistance to targeted therapy and immunotherapy in non-small cell lung cancer (NSCLC) is a significant challenge in the treatment of this disease. The mechanisms of resistance are multifactorial and include molecular target alterations and activation of alternative pathways, tumor heterogeneity and tumor microenvironment change, immune evasion, and immunosuppression. Promising strategies for overcoming resistance include the development of combination therapies, understanding the resistance mechanisms to better use novel drug targets, the identification of biomarkers, the modulation of the tumor microenvironment and so on. Ongoing research into the mechanisms of resistance and the development of new therapeutic approaches hold great promise for improving outcomes for patients with NSCLC. Here, we summarize diverse mechanisms driving resistance to targeted therapy and immunotherapy in NSCLC and the latest potential and promising strategies to overcome the resistance to help patients who suffer from NSCLC.

Allelic Context of EGFR C797X-Mutant Lung Cancer Defines Four Subtypes With Heterogeneous Genomic Landscape and Distinct Clinical Outcomes

INTRODUCTION

EGFR C797X (C797S or C797G) mutation is the most frequent on-target mechanism of resistance to osimertinib. The hypothesis that the allelic context of C797X/T790M has implications for treatment is on the basis of sporadic reports and needs validation with larger cohorts.

METHODS

We identified patients with EGFR C797X-mutant NSCLC from nine centers who progressed on osimertinib, all analyzed in a single laboratory through next-generation sequencing. We analyzed genomic profiles and assessed associations between clinical outcomes and C797X status.

RESULTS

A total of 365 EGFR C797X-mutant cases were categorized into four subtypes on the basis of allelic context: in cis (75.3%), in trans (6.4%), cis&trans (10.4%), and C797X-only (7.9%). Genomically, the cis&trans subtype displayed the highest frequency of concurrent alterations at osimertinib resistance sites (21.1%), while the in cis subtype had the lowest (8.4%). Clinically, cis&trans patients exhibited the worst progression-free survival (PFS) on both previous (median 7.7 mo) and subsequent treatment (median 1.0 mo) and overall survival (median 3.9 mo). In subsequent treatments, in cis patients exhibited superior PFS with combined brigatinib and cetuximab (median 11.0 mo) compared with other regimens (p = 0.005), while in trans patients exhibited variable outcomes with combined first or second- and third-generation EGFR inhibitor (PFS range: 0.7-8.1 mo, median 2.6 mo). Notably, subtype switching was observed after subsequent treatments, predominantly toward the in cis subtype.

CONCLUSIONS

Allelic context could define four EGFR C797X-mutant NSCLC subtypes with heterogeneous genetic landscapes and distinct clinical outcomes. Subsequent treatments further complicate the scenario through subtype switching.

EGFR degraders in non-small-cell lung cancer: Breakthrough and unresolved issue

The epidermal growth factor receptor (EGFR) has been well validated as a therapeutic target for anticancer drug discovery. Osimertinib has become the first globally accessible third-generation EGFR inhibitor, representing one of the most advanced developments in non-small-cell lung cancer (NSCLC) therapy. However, a tertiary Cys797 to Ser797 (C797S) point mutation has hampered osimertinib treatment in patients with advanced EGFR-mutated NSCLC. Several classes of fourth-generation EGFR inhibitors were consequently discovered with the aim of overcoming the EGFRC797S mutation-mediated resistance. However, no clinical efficacy data of the fourth-generation EGFR inhibitors were reported to date, and EGFRC797S mutation-mediated resistance remains an "unmet clinical need." Proteolysis-targeting chimeric molecules (PROTACs) obtained from EGFR-TKIs have been developed to target drug resistance EGFR in NSCLC. Some PROTACs are from nature products. These degraders compared with EGFR inhibitors showed better efficiency in their cellular potency, inhibition, and toxicity profiles. In this review, we first introduce the structural properties of EGFR, the resistance, and mutations of EGFR, and then mainly focus on the recent advances of EGFR-targeting degraders along with its advantages and outstanding challenges.

Safety and efficacy of SNK01 (autologous natural killer cells) in combination with cytotoxic chemotherapy and/or cetuximab after failure of prior tyrosine kinase inhibitor in non-small cell lung cancer: non-clinical mouse model and phase I/IIa clinical study

BACKGROUND

Choosing treatments for epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC) patients with osimertinib resistance is challenging. We evaluated the safety and efficacy of SNK01 (autologous natural killer (NK) cells) in combination with cytotoxic chemotherapy and/or cetuximab (an anti-EGFR monoclonal antibody) in treating EGFR-mutated NSCLC in this non-clinical and phase I/IIa clinical trial.

METHODS

We developed a cell line-derived xenograft-humanized mouse model with an osimertinib-resistant lung cancer cell line. The mice were divided into four groups based on treatment (no treatment, cetuximab, SNK01, and combination groups) and treated weekly for 5 weeks. In the clinical study, 12 patients with EGFR-mutated NSCLC who failed prior tyrosine kinase inhibitor (TKI) received SNK01 weekly in combination with gemcitabine/carboplatin (n=6) or cetuximab/gemcitabine/carboplatin (n=6) and dose escalation of SNK01 following the "3+3" design.

RESULTS

In the non-clinical study, an increase in NK cells in the blood and enhanced NK cell tumor infiltration were observed in the SNK01 group. The volume of tumor extracted after treatment was the smallest in the combination group. In the clinical study, 12 patients (median age, 60.9 years; all adenocarcinoma cases) received SNK01 weekly for 7-8 weeks (4×109 cells/dose (n=6); 6×109 cells/dose (n=6)). The maximum feasible dose of SNK01 was 6×109 cells/dose without dose-limiting toxicity. Efficacy outcomes showed an objective response rate of 25%, disease control rate of 100%, and median progression-free survival of 143 days.

CONCLUSION

SNK01 in combination with cytotoxic chemotherapy, including cetuximab, for EGFR-mutated NSCLC with TKI resistance was safe and exerted a potential antitumor effect.

TRIAL REGISTRATION NUMBER

NCT04872634.

Clinical utility of Next Generation Sequencing of plasma cell-free DNA for the molecular profiling of patients with NSCLC at diagnosis and disease progression

BACKGROUND

The present study evaluates the utility of NGS analysis of circulating free DNA (cfDNA), which incorporates small amounts of tumor DNA (ctDNA), at diagnosis or at disease progression (PD) in NSCLC patients.

METHODS

Comprehensive genomic profiling on cfDNA by NGS were performed in NSCLC patients at diagnosis (if tissue was unavailable/insufficient) or at PD to investigate potential druggable molecular aberrations. Blood samples were collected as routinary diagnostic procedures, DNA was extracted, and the NextSeq 550 Illumina platform was used to run the Roche Avenio ctDNA Expanded Kit for molecular analyses. Gene variants were classified accordingly to the ESCAT score.

RESULTS

A total of 106 patients were included in this study; 44 % of cases were requested because of tissue unavailability at the diagnosis and 56 % were requested at the PD. At least one driver alteration was observed in 62 % of cases at diagnosis. Driver druggable variants classified as ESCAT level I were detected in 34 % of patients, including ALK-EML4, ROS1-CD74, EGFR, BRAF, KRAS p.G12C, PI3KCA. In the PD group, most patients were EGFR-positive, progressing to a first line-therapy. Sixty-three percent of patients had at least one driver alteration detected in blood and 17 % of patients had a known biological mechanism of resistance allowing further therapeutic decisions.

CONCLUSIONS

The present study confirms the potential of liquid biopsy to detect tumour molecular heterogeneity in NSCLC patients at the diagnosis and at PD, demonstrating that a significant number of druggable mutations and mechanisms of resistance can be detected by NGS analysis on ctDNA.

Stevens-Johnson syndrome induced by toripalimab in a previously EGFR-TKI-treated advanced lung adenocarcinoma patient harboring EGFR mutations 19 del/T790M/C797S in trans and cis: a case report

Background: The treatment paradigm for advanced non-small-cell lung cancer (NSCLC) is rapidly changing. Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) and anti-programmed death-1 (PD-1) antibodies have increasingly been incorporated into routine care for nearly all patients with NSCLC. Toripalimab was recently approved as the first-line treatment for advanced non-squamous NSCLC in combination with chemotherapy. Stevens-Johnson syndrome (SJS) is a rare but potentially fatal complication of TKI and anti-PD-1 therapy. We reported a case of SJS after sequential use of EGFR-TKIs and toripalimab in an NSCLC patient with EGFR mutations 19 del/T790M/C797S in trans and cis. Case presentation: A 58-year-old man with stage IV NSCLC received gefitinib because next-generation sequencing (NGS) revealed an EGFR 19del, followed by osimertinib and pemetrexed with the emergence of EGFR T790M. Four EGFR mutations 19 del/T790M/C797S in trans and cis were detected after osimertinib resistance. The combination of toripalimab and docetaxel was administered as a third-line treatment. The patient developed SJS at 21 days, and toripalimab was discontinued. After treatment with methylprednisolone and prednisolone, the skin toxicity of the patient gradually decreased and eventually disappeared. The patient received osimertinib and anlotinib after recovery, and SJS has not recurred. The ongoing treatment is still effective and results in stable disease. Conclusion: We reported the first case of SJS induced by toripalimab in a patient with lung adenocarcinoma harboring multiple EGFR mutations. The TKI treatment after SJS was well tolerated and effective.

20 years since the approval of first EGFR-TKI, gefitinib: Insight and foresight

Epidermal growth factor receptor (EGFR) actively involves in modulation of various cancer progression related mechanisms including angiogenesis, differentiation and migration. Therefore, targeting EGFR has surfaced as a prominent approach for the treatment of several types of cancers, including non-small cell lung cancer (NSCLC), pancreatic cancer, glioblastoma. Various first, second and third generation of EGFR tyrosine kinase inhibitors (EGFR-TKIs) have demonstrated effectiveness as an anti-cancer therapeutics. However, rapid development of drug resistance and mutations still remains a major challenge for the EGFR-TKIs therapy. Overcoming from intrinsic and acquired resistance caused by EGFR mutations warrants the further exploration of alternative strategies and discovery of novel inhibitors. In this review, we delve into the breakthrough discoveries have been made in previous 20 years, and discuss the currently ongoing efforts aimed to circumvent the chemo-resistance. We also highlight the new challenges, limitations and future directions for the development of improved therapeutic approaches such as fourth-generation EGFR-TKIs, peptides, nanobodies, PROTACs etc.

Comprehensive genomic profiling of Japanese patients with thoracic malignancies: A single-center retrospective study

BACKGROUND

Few studies have been conducted on comprehensive genomic profiling (CGP) panels in Japanese patients with thoracic malignancies after completing standard treatment. Consequently, its value in clinical practice remains unclear.

METHODS

We conducted a retrospective study of Japanese patients with thoracic malignancies who underwent CGP between June 2019 and November 2022 at our hospital. We evaluated the detection rate of actionable genetic alterations and percentage of patients who received genomically-matched therapy. Furthermore, we examined the value of the CGP panel in patients who underwent multiplex gene-panel testing prior to their initial treatment. This study was performed in accordance with the principles of the Declaration of Helsinki.

RESULTS

The study included 56 patients, of whom 47 (83.9%) had actionable genetic alterations and 8 (14.3%) received genomically-matched therapy. Of these, four patients were treated with approved drugs and three patients were treated with investigational agents. In addition, one patient was treated with approved drugs using the patient-directed care system. Of the 17 patients who had multiplex gene-panel testing performed at the start of their initial therapy, two (11.8%) were newly identified by the CGP panel and subsequently received genomically-matched therapy. EGFR L718Q and MET amplification were observed in two of the seven patients with epidermal growth factor receptor-tyrosine kinase inhibitor resistance.

CONCLUSIONS

The CGP panel could identify genetic alterations, thereby facilitating genomically-matched therapy, even in patients with thoracic malignancies who could not be identified using multiplex gene-panel testing.

Efficacy and safety of re-challenging 160 mg furmonertinib for advanced NSCLC after resistance to third-generation EGFR-TKIs targeted agents: A real-world study

BACKGROUND

Third-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI) show good selectivity for classical EGFR mutated and EGFR T790M mutated non-small cell lung cancer (NSCLC). However, resistance inevitably occurs to third-generation EGFR-TKI. This study describes the real-world characteristics, efficacy, and safety of treating post-progression NSCLC with 160 mg of furmonertinib (in combination with or without anti-angiogenic agents and chemotherapy) with third-generation EGFR-TKIs.

METHODS

EGFR-mutated NSCLC patients with intracranial progression pattern cohort (IP cohort) or extracranial progression pattern cohort (EP cohort) were retrospectively analyzed following progression to third-generation EGFR-TKIs receiving furmonertinib 160 mg daily as second-line or later treatment in combination with or without anti-angiogenic agents and chemotherapy.

RESULTS

Thirty-nine patients were included and categorized into two groups according to the progression pattern. Then, 22 patients in the IP cohort and 17 patients in the EP cohort, most of whom were in poor physical condition, were included and 84.6% had central nervous system metastases. In the IP cohort, the median PFS was 5.5 months (95% CI 4.67-8.72), and the median OS was 9.8 months (95% CI 7.25-11.20) for single-agent furmonertinib or combination therapy. In the EP cohort, the median PFS was 3.2 months (95% CI 2.18-4.70), and the median OS was 6.7 months (95% CI 4.99-8.75). Univariate analysis showed the association between the presence of a prior T790M mutation and a history of combined radiotherapy with longer PFS with furmonertinib (p = 0.048, p = 0.004). Overall, adverse events (AEs) of any grade occurred in 84.6% of patients (33/39), with the majority having grade 2 or lower AEs.

CONCLUSION

Furmonertinib 160 mg is an optional regimen for patients with advanced NSCLC who develop resistance after treatment with third-generation EGFR-TKIs, especially those developing resistance due to the progression of intracranial lesions, with good efficacy and an acceptable safety profile that warrants further exploration.

Fluctuation of Acquired Resistance Mutations and Re-Challenge with EGFR TKI in Metastatic NSCLC: A Case Report

Osimertinib has become the preferred first-line therapy for epidermal growth factor receptor (EGFR) mutation-positive metastatic non-small cell lung cancer (NSCLC) in recent years. Originally, it was approved for second-line treatment after epidermal growth factor receptor EGFR tyrosine kinase inhibitors (TKIs) of the first and second generations had failed and EGFR T790M had emerged as a mode of resistance. Osimertinib itself provokes a wide array of on- and off-target molecular alterations that can limit therapeutic success. Liquid biopsy ctDNA (circulating tumor DNA) analysis by hybrid capture (HC) next-generation sequencing (NGS) can help to identify alterations in a minimally invasive way and allows for the detection of common as well as rare resistance alterations. We describe a young female patient who was initially diagnosed with metastatic EGFR L858R-positive NSCLC. She received EGFR TKI therapy at different timepoints during the course of the disease and developed sequential EGFR resistance alterations (EGFR T790M and C797S). In the course of her disease, resistance alteration became undetectable, and the tumor was successfully rechallenged with the original first-generation EGFR TKI as well as osimertinib and altogether showed prolonged response despite a prognostically negative TP53 alteration. To date, the patient has been alive for more than seven years, though initially diagnosed with a heavy metastatic burden.

Mathematical analysis identifies the optimal treatment strategy for epidermal growth factor receptor-mutated non-small cell lung cancer

Introduction

In Asians, more than half of non-small cell lung cancers (NSCLC) are induced by epidermal growth factor receptor (EGFR) mutations. Although patients carrying EGFR driver mutations display a good initial response to EGFR-Tyrosine Kinase Inhibitors (EGFR-TKIs), additional mutations provoke drug resistance. Hence, predicting tumor dynamics before treatment initiation and formulating a reasonable treatment schedule is an urgent challenge.

Methods

To overcome this problem, we constructed a mathematical model based on clinical observations and investigated the optimal schedules for EGFR-TKI therapy.

Results

Based on published data on cell growth rates under different drugs, we found that using osimertinib that are efficient for secondary resistant cells as the first-line drug is beneficial in monotherapy, which is consistent with published clinical statistical data. Moreover, we identified the existence of a suitable drug-switching time; that is, changing drugs too early or too late was not helpful. Furthermore, we demonstrate that osimertinib combined with erlotinib or gefitinib as first-line treatment, has the potential for clinical application. Finally, we examined the relationship between the initial ratio of resistant cells and final cell number under different treatment conditions, and summarized it into a therapy suggestion map. By performing parameter sensitivity analysis, we identified the condition where　osimertinib-first therapy was recommended as the optimal treatment option.

Discussion

This study for the first time theoretically showed the optimal treatment strategies based on the known information in NSCLC. Our framework can be applied to other types of cancer in the future.

Tackling Osimertinib Resistance in EGFR-Mutant Non-Small Cell Lung Cancer

The current landscape of targeted therapies directed against oncogenic driver alterations in non-small cell lung cancer (NSCLC) is expanding. Patients with EGFR-mutant NSCLC can derive significant benefit from EGFR tyrosine kinase inhibitor (TKI) therapy, including the third-generation EGFR TKI osimertinib. However, invariably, all patients will experience disease progression with this therapy mainly due to the adaptation of cancer cells through primary or secondary molecular mechanisms of resistance. The comprehension and access to tissue and cell-free DNA next-generation sequencing have fueled the development of innovative therapeutic strategies to prevent and overcome resistance to osimertinib in the clinical setting. Herein, we review the biological and clinical implications of molecular mechanisms of osimertinib resistance and the ongoing development of therapeutic strategies to overcome or prevent resistance.

Targeted Strategies for Degradation of Key Transmembrane Proteins in Cancer

Targeted protein degradation is an attractive technology for cancer treatment due to its ability to overcome the unpredictability of the small molecule inhibitors that cause resistance mutations. In recent years, various targeted protein degradation strategies have been developed based on the ubiquitin-proteasome system in the cytoplasm or the autophagy-lysosomal system during endocytosis. In this review, we describe and compare technologies for the targeted inhibition and targeted degradation of the epidermal growth factor receptor (EGFR), one of the major proteins responsible for the onset and progression of many types of cancer. In addition, we develop an alternative strategy, called alloAUTO, based on the binding of new heterocyclic compounds to an allosteric site located in close proximity to the EGFR catalytic site. These compounds cause the targeted degradation of the transmembrane receptor, simultaneously activating both systems of protein degradation in cells. Damage to the EGFR signaling pathways promotes the inactivation of Bim sensor protein phosphorylation, which leads to the disintegration of the cytoskeleton, followed by the detachment of cancer cells from the extracellular matrix, and, ultimately, to cancer cell death. This hallmark of targeted cancer cell death suggests an advantage over other targeted protein degradation strategies, namely, the fewer cancer cells that survive mean fewer chemotherapy-resistant mutants appear.

Novel systemic therapies in the management of tyrosine kinase inhibitor-pretreated patients with epidermal growth factor receptor-mutant non-small-cell lung cancer

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are the standard first-line option for non-small-cell lung cancer (NSCLC) harboring active EGFR mutations. The overall survival of patients with advanced NSCLC has improved dramatically with the development of comprehensive genetic profiles and targeted therapies. However, resistance inevitably occurs, leading to disease progression after approximately 10-18 months of EGFR-TKI treatment. Platinum-based chemotherapy is the standard treatment for patients who have experienced disease progression while undergoing EGFR-TKI treatment, but its efficacy is limited. The management of extensively pretreated patients with EGFR-mutant NSCLC is becoming increasingly concerning. New agents have shown encouraging efficacy in clinical trials for this patient population, including fourth-generation EGFR-TKIs, EGFR-TKIs combined with counterpart targeted drugs, and novel agents such as antibody-drug conjugates. We review current efforts to manage extensively pretreated patients with EGFR-mutant NSCLC.

BBT-176, a Novel Fourth-Generation Tyrosine Kinase Inhibitor for Osimertinib-Resistant EGFR Mutations in Non-Small Cell Lung Cancer

PURPOSE

Resistance to third-generation EGFR inhibitors including osimertinib arises in part from the C797S mutation in EGFR. Currently, no targeted treatment option is available for these patients. We have developed a new EGFR tyrosine kinase inhibitor (TKI), BBT-176, targeting the C797S mutation.

PATIENTS AND METHODS

Recombinant EGFR proteins and Ba/F3 cell lines, patient-derived cells, and patient-derived xenografts expressing mutant EGFRs were used to test the inhibitory potency and the anticancer efficacy of BBT-176 both in vitro and in vivo. Patient case data are also available from an ongoing phase I clinical trial (NCT04820023).

RESULTS

The half maximal inhibitory concentration (IC50) of BBT-176 against EGFR 19Del/C797S, EGFR 19Del/T790M/C797S, and EGFR L858R/C797S proteins were measured at 4.36, 1.79, and 5.35 nmol/L, respectively (vs. 304.39, 124.82, and 573.72 nmol/L, for osimertinib). IC50 values of BBT-176 against Ba/F3 cells expressing EGFR 19Del/C797S, EGFR 19Del/T790M/C797S, EGFR L858R/C797S, and EGFR L858R/T790M/C797S were 42, 49, 183, and 202 nmol/L, respectively (vs. 869, 1,134, 2,799, and 2,685 nmol/L for osimertinib). N-ethyl-N-nitrosourea mutagenesis suggested that BBT-176 treatment does not introduce any secondary mutations in the EGFR gene but increases EGFR expression levels. Combined with the EGFR antibody cetuximab, BBT-176 effectively suppressed the growth of BBT-176-resistant clones. BBT-176 strongly inhibited the tumor growth, and in some conditions induced tumor regression in mouse models. In the clinical trial, two patients harboring EGFR 19Del/T790M/C797S in blood showed tumor shrinkage and radiologic improvements.

CONCLUSIONS

BBT-176 is a fourth-generation EGFR inhibitor showing promising preclinical activity against NSCLC resistant to current EGFR TKI, with early clinical efficacy and safety.

Insights into fourth generation selective inhibitors of (C797S) EGFR mutation combating non-small cell lung cancer resistance: a critical review

Lung cancer is the second most common cause of morbidity and mortality among cancer types worldwide, with non-small cell lung cancer (NSCLC) representing the majority of most cases. Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) are among the most commonly used targeted therapy to treat NSCLC. Recent years have seen the evaluation of many synthetic EGFR TKIs, most of which showed therapeutic activity in pertinent models and were classified as first, second, and third-generation. The latest studies have concluded that their efficacy was also compromised by additional acquired mutations, including C797S. Because second- and third-generation EGFR TKIs are irreversible inhibitors, they are ineffective against C797S containing EGFR triple mutations (Del19/T790M/C797S and L858R/T790M/C797S). Therefore, there is an urgent unmet medical need to develop next-generation EGFR TKIs that selectively inhibit EGFR triple mutations via a non-irreversible mechanism. This review covers the fourth-generation EGFR-TKIs' most recent design with their essential binding interactions, the clinical difficulties, and the potential outcomes of treating patients with EGFR mutation C797S resistant to third-generation EGFR-TKIs was also discussed. Moreover, the utilization of various therapeutic strategies, including multi-targeting drugs and combination therapies, has also been reviewed.

The Resistance to EGFR-TKIs in Non-Small Cell Lung Cancer: From Molecular Mechanisms to Clinical Application of New Therapeutic Strategies

Almost 17% of Western patients affected by non-small cell lung cancer (NSCLC) have an activating epidermal growth factor receptor (EGFR) gene mutation. Del19 and L858R are the most-common ones; they are positive predictive factors for EGFR tyrosine kinase inhibitors (TKIs). Currently, osimertinib, a third-generation TKI, is the standard first-line therapy for advanced NSCLC patients with common EGFR mutations. This drug is also administered as a second-line treatment for those patients with the T790M EGFR mutation and previously treated with first- (erlotinib, gefitinib) or second- (afatinib) generation TKIs. However, despite the high clinical efficacy, the prognosis remains severe due to intrinsic or acquired resistance to EGRF-TKIs. Various mechanisms of resistance have been reported including the activation of other signalling pathways, the development of secondary mutations, the alteration of the downstream pathways, and phenotypic transformation. However, further data are needed to achieve the goal of overcoming resistance to EGFR-TKIs, hence the necessity of discovering novel genetic targets and developing new-generation drugs. This review aimed to deepen the knowledge of intrinsic and acquired molecular mechanisms of resistance to EGFR-TKIs and the development of new therapeutic strategies to overcome TKIs' resistance.

Toward the next generation EGFR inhibitors: an overview of osimertinib resistance mediated by EGFR mutations in non-small cell lung cancer

Epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) is currently the standard first-line therapy for EGFR-mutated advanced non-small cell lung cancer (NSCLC). The life quality and survival of this subgroup of patients were constantly improving owing to the continuous iteration and optimization of EGFR-TKI. Osimertinib, an oral, third-generation, irreversible EGFR-TKI, was initially approved for the treatment of NSCLC patients carrying EGFR T790M mutations, and has currently become the dominant first-line targeted therapy for most EGFR mutant lung cancer. Unfortunately, resistance to osimertinib inevitably develops during the treatment and therefore limits its long-term effectiveness. For both fundamental and clinical researchers, it stands for a major challenge to reveal the mechanism, and a dire need to develop novel therapeutics to overcome the resistance. In this article, we focus on the acquired resistance to osimertinib caused by EGFR mutations which account for approximately 1/3 of all reported resistance mechanisms. We also review the proposed therapeutic strategies for each type of mutation conferring resistance to osimertinib and give an outlook to the development of the next generation EGFR inhibitors. Video Abstract.

Making the Best Use of Available Weapons for the Inevitable Rivalry-Resistance to EGFR-TKIs

The emergence of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) revolutionized the treatment of advanced-stage non-small cell lung cancer (NSCLC). Detected in more than 50% of late-stage lung adenocarcinoma in Asian patients, the EGFR mutation was regarded as a golden mutation for Asians. However, resistance to TKIs seems inevitable and severely hinders patients from getting further benefits from treatment. Even though resistance caused by EGFR T790M could be effectively managed by third-generation EGFR-TKIs currently, resistance to third-generation EGFR-TKIs is still a troublesome issue faced by both clinicians and patients. Various efforts have been made to maximize the benefits of patients from EGFR-TKIs therapy. Thus, new requirements and challenges have been posed to clinicians of this era. In this review, we summarized the clinical evidence on the efficacy of third-generation EGFR-TKIs in patients with EGFR-mutated NSCLC. Then, we discussed advancements in sequential treatment aiming to delay the onset of resistance. Moreover, the resistance mechanisms and features were depicted to help us better understand our enemies. Lastly, we put forward future strategies, including recent approaches involving the utilization of antibody drug conjugates against resistance and research directions about shaping the evolution of NSCLC as a core idea in the management of NSCLC.

Can Liquid Biopsy Based on ctDNA/cfDNA Replace Tissue Biopsy for the Precision Treatment of EGFR-Mutated NSCLC?

More and more clinical trials have explored the role of liquid biopsy in the diagnosis and treatment of EGFR-mutated NSCLC. In certain circumstances, liquid biopsy has unique advantages and offers a new way to detect therapeutic targets, analyze drug resistance mechanisms in advanced patients, and monitor MRD in patients with operable NSCLC. Although its potential cannot be ignored, more evidence is needed to support the transition from the research stage to clinical application. We reviewed the latest progress in research on the efficacy and resistance mechanisms of targeted therapy for advanced NSCLC patients with plasma ctDNA EGFR mutation and the evaluation of MRD based on ctDNA detection in perioperative and follow-up monitoring.

Osimertinib Resistance: Molecular Mechanisms and Emerging Treatment Options

The development of tyrosine kinase inhibitors (TKIs) targeting the mutant epidermal growth factor receptor (EGFR) protein initiated the success story of targeted therapies in non-small-cell lung cancer (NSCLC). Osimertinib, a third-generation EGFR-TKI, is currently indicated as first-line therapy in patients with NSCLC with sensitizing EGFR mutations, as second-line therapy in patients who present the resistance-associated mutation T790M after treatment with previous EGFR-TKIs, and as adjuvant therapy for patients with early stage resected NSCLC, harboring EGFR mutations. Despite durable responses in patients with advanced NSCLC, resistance to osimertinib, similar to other targeted therapies, inevitably develops. Understanding the mechanisms of resistance, including both EGFR-dependent and -independent molecular pathways, as well as their therapeutic potential, represents an unmet need in thoracic oncology. Interestingly, differential resistance mechanisms develop when osimertinib is administered in a first-line versus second-line setting, indicating the importance of selection pressure and clonal evolution of tumor cells. Standard therapeutic approaches after progression to osimertinib include other targeted therapies, when a targetable genetic alteration is detected, and cytotoxic chemotherapy with or without antiangiogenic and immunotherapeutic agents. Deciphering the when and how to use immunotherapeutic agents in EGFR-positive NSCLC is a current challenge in clinical lung cancer research. Emerging treatment options after progression to osimertinib involve combinations of different therapeutic approaches and novel EGFR-TKI inhibitors. Research should also be focused on the standardization of liquid biopsies in order to facilitate the monitoring of molecular alterations after progression to osimertinib.

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.

Mechanisms of EGFR-TKI-Induced Apoptosis and Strategies Targeting Apoptosis in EGFR-Mutated Non-Small Cell Lung Cancer

Homeostasis is achieved by balancing cell survival and death. In cancer cells, especially those carrying driver mutations, the processes and signals that promote apoptosis are inhibited, facilitating the survival and proliferation of these dysregulated cells. Apoptosis induction is an important mechanism underlying the therapeutic efficacy of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) for EGFR-mutated non-small cell lung cancer (NSCLC). However, the mechanisms by which EGFR-TKIs induce apoptosis have not been fully elucidated. A deeper understanding of the apoptotic pathways induced by EGFR-TKIs is essential for the developing novel strategies to overcome resistance to EGFR-TKIs or to enhance the initial efficacy through therapeutic synergistic combinations. Recently, therapeutic strategies targeting apoptosis have been developed for cancer. Here, we review the state of knowledge on EGFR-TKI-induced apoptotic pathways and discuss the therapeutic strategies for enhancing EGFR-TKI efficiency. We highlight the great progress achieved with third-generation EGFR-TKIs. In particular, combination therapies of EGFR-TKIs with anti-vascular endothelial growth factor/receptor inhibitors or chemotherapy have emerged as promising therapeutic strategies for patients with EGFR-mutated NSCLC. Nevertheless, further breakthroughs are needed to yield an appropriate standard care for patients with EGFR-mutated NSCLC, which requires gaining a deeper understanding of cancer cell dynamics in response to EGFR-TKIs.

Defining the sensitivity landscape of EGFR variants to tyrosine kinase inhibitors

Tyrosine kinase inhibitor (TKI) is a standard treatment for patients with NSCLC harboring constitutively active epidermal growth factor receptor (EGFR) mutations. However, most rare EGFR mutations lack treatment regimens except for the well-studied ones. We constructed two EGFR variant libraries containing substitutions, deletions, or insertions using the saturation mutagenesis method. All the variants were located in the EGFR mutation hotspot (exons 18-21). The sensitivity of these variants to afatinib, erlotinib, gefitinib, icotinib, and osimertinib was systematically studied by determining their enrichment in massively parallel cytotoxicity assays using an endogenous EGFR-depleted cell line. A total of 3914 and 70,475 variants were detected in the constructed EGFR Substitution-Deletion (Sub-Del) and exon 20 Insertion (Ins) libraries. Of the 3914 Sub-Del variants, 221 proliferated fast in the control assay and were sensitive to EGFR-TKIs. For the 70,475 Ins variants, insertions at amino acid positions 770-774 were highly enriched in all 5 TKI cytotoxicity assays. Moreover, the top 5% of the enriched insertion variants included a glycine or serine insertion at high frequency. We present a comprehensive reference for the sensitivity of EGFR variants to five commonly used TKIs. The approach used here should be applicable to other genes and targeted drugs. BACKGROUND: Tyrosine kinase inhibitors (TKIs) therapy is a standard treatment for patients with advanced non-small-cell lung carcinoma (NSCLC) when activating epidermal growth factor receptor (EGFR) mutations are detected. However, except for the well-studied EGFR mutations, most EGFR mutations lack treatment regimens. TRANSLATIONAL SIGNIFICANCE: The results demonstrated that patients with rare EGFR mutations were most likely to benefit from osimertinib therapy compared to afatinib, erlotinib, gefitinib, or icotinib therapy. This study provides a case of deep mutational scanning that simultaneously assayed substitution, deletion, and insertion variants. This approach is applicable for other oncogenes and targeted drugs.

New Strategies and Novel Combinations in EGFR TKI-Resistant Non-small Cell Lung Cancer

OPINION STATEMENT

Osimertinib is the current standard-of-care for the first-line treatment of Epidermal Growth Factor Receptor (EGFR)-mutant non-small cell lung cancer (NSCLC). Progression after osimertinib ineluctably occurs, and standard of care treatment options beyond progression have mainly included next-line platinum doublet chemotherapy. With better understanding of the varied molecular mechanisms of resistance to osimertinib, several opportunities for the use of targeted agents are emerging that include MET amplification, observed in 15% of patients, and resistant EGFR mutations, including C797S in 7% of patients. Evidence for the use of targeted therapies in such situations is mostly based on case reports, but clinical trials are being conducted with MET inhibitors, such as amivantamab, an EGFR-MET bispecific antibody, or next-generation EGFR inhibitors, such as patritumab-deruxtecan, a HER3 antibody drug conjugate. In this review, we outline our proposed approach to current clinical practice for patients with EGFR mutant, osimertinib-resistant NSCLC which includes the following potential strategies: - Continuation of osimertinib beyond progression following local ablative treatment of oligoprogressive disease, - Tissue rebiopsy of progressive site and possibly concurrent liquid biopsy to evaluate for mechanism of resistance utilizing comprehensive genomic profiling, -Discussion at a molecular tumor board for assessment for enrollment in clinical trials/expanded access program if available with innovative drugs or possible off-label use of available targeted agents, based on the results of molecular profiling, -If no mechanism of resistance identified, administration of platinum-based chemotherapy with antiangiogenic agents. The role of immunotherapy will also be addressed given the uncertain benefit.

PD-1/PD-L1 combined with LAG3 is associated with clinical activity of immune checkpoint inhibitors in metastatic primary pulmonary lymphoepithelioma-like carcinoma

Primary pulmonary lymphoepithelioma-like carcinoma (PLELC) is an Epstein–Barr virus (EBV)-related, rare subtype of non-small-cell lung cancer (NSCLC). Immune checkpoint inhibitors (ICI) show durable responses in advanced NSCLC. However, their effects and predictive biomarkers in PLELC remain poorly understood. We retrospectively analyzed the data of 48 metastatic PLELC patients treated with ICI. Pretreated paraffin-embedded specimens (n = 19) were stained for PD-1, PD-L1, LAG3, TIM3, CD3, CD4, CD8, CD68, FOXP3, and cytokeratin (CK) by multiple immunohistochemistry (mIHC). Next-generation sequencing was performed for 33 PLELC samples. Among patients treated with ICI monotherapy (n = 30), the objective response rate (ORR), disease control rate (DCR), median progression-free survival (mPFS), and overall survival (mOS) were 13.3%, 80.0%, 7.7 months, and 24.9 months, respectively. Patients with PD-L1 ≥1% showed a longer PFS (8.4 vs. 2.1 months, p = 0.015) relative to those with PD-L1 <1%. Among patients treated with ICI combination therapy (n = 18), ORR, DCR, mPFS, and mOS were 27.8%, 100.0%, 10.1 months, and 19.7 months, respectively. Patients with PD-L1 ≥1% showed a significantly superior OS than those with PD-L1 <1% (NA versus 11.7 months, p = 0.001). Among the 19 mIHC patients, those with high PD-1/PD-L1 and LAG3 expression showed a longer PFS (19.0 vs. 3.9 months, p = 0.003). ICI also showed promising efficacy for treating metastatic PLELC. PD-L1 may be both predictive of ICI treatment efficacy and prognostic for survival in PLELC. PD-1/PD-L1 combined with LAG3 may serve as a predictor of ICI treatment effectiveness in PLELC. Larger and prospective trials are warranted to validate both ICI activity and predictive biomarkers in PLELC.

This study was partly presented as a poster at the IASLC 20th World Conference on Lung Cancer 2019, 7–10 September 2019, Barcelona, Spain.

EGFR-TKI re-administration after osimertinib failure in T790M mutation loss cases with re-biopsy

Data on the re-administration of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) after osimertinib failure in patients with T790M-positive non-small cell lung cancer (NSCLC) is limited. EGFR-TKI re-administration efficacy may vary between patients with T790M loss and those with T790M persistent with re-biopsy after osimertinib treatment. Patients who received EGFR-TKI re-administration (gefitinib, erlotinib, afatinib, dacomitinib, and osimertinib) after osimertinib failure were identified from our database. T790M mutation status before EGFR-TKI re-administration was analyzed via repeat biopsy. We retrospectively evaluated the efficacy of EGFR-TKI re-administration, especially differences according to the T790M mutation status, via repeat biopsy. Until June 2020, 28 patients received EGFR-TKI re-administration and 17 underwent repeat biopsy after osimertinib failure. Patients were divided into three groups, including the T790M loss group, where active mutation persisted and T790M was lost (13/17); T790M remaining group, where both the active mutation and T790M persisted (3/17); and active mutation loss group where both the active mutation and T790M were lost (1/17). The overall response rate (ORR) of EGFR-TKI re-administration in the T790M loss group was 31% and the disease control rate (DCR) was 54%, which were higher than the ORR of 21% and DCR of 43% in the entire patient population. ORR and DCR of the not re-biopsy group were low (9% and 27%, respectively). The therapeutic effect of EGFR-TKI re-administration in patients with T790M-positive NSCLC after osimertinib failure is limited. EGFR-TKI re-administration may be considered in cases of T790M loss after repeat biopsy.

EGFR-mutant NSCLC: monitoring the molecular evolution of tumors in 2022

INTRODUCTION

Epidermal growth factor receptor (EGFR) activating mutations define a subset of advanced, metastatic non-small cell lung cancers (NSCLCs), that was historically identified along with the clinical development of specific EGFR tyrosine kinase inhibitors (TKIs), opening the era of precision medicine in thoracic oncology.

AREAS COVERED

Progression after EGFR TKIs is a major challenge for patients, as it occurs ineluctably along with disease evolution. Osimertinib is the current standard-of-care for the first-line treatment of EGFR-mutant NSCLC. Mechanisms of resistance to osimertinib are challenging to identify, and are dominated by MET pathway activation, and acquired EGFR mutations.

EXPERT OPINION

The current vision for clinical practice in patients with EGFR-mutant NSCLC developing disease progression after osimertinib includes the following 5 steps:- continuation of osimertinib beyond progression, and local treatment of oligoprogressive disease, - comprehensive genomic profiling based on tissue rebiopsy of progressing sites, - access to new treatment agents through clinical trials, - molecular tumor board to discuss the off-label use of targeted agents, depending on the availability of drugs and/or expanded access programs - chemotherapy may be the best choice, based on combination of platinum-based regimen and antiangiogenic agents and possibly immune checkpoint inhibitors.

L718Q/V mutation in exon 18 of EGFR mediates resistance to osimertinib: clinical features and treatment

Osimertinib, a mutant-specific third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), is emerging as the preferred first-line of treatment for EGFR-mutant lung cancer. However, osimertinib resistance inevitably develops among patients treated with the drug. The modal resistance mechanisms of osimertinib include the occurrence of epithelial transition factor (c-MET) amplification and C797S mutation, whereas rare mutations are presented as case reports. Recently, the L718Q/V mutation in exon 18 of EGFR has been reported to contribute to one of the possible mechanisms of resistance. The clinical features and subsequent treatment strategies for this mutation require further research. This study retrospectively enrolled NSCLC patients with the L718Q/V mutation from 2017 to 2021 at the Cancer Hospital of the University of the Chinese Academy of Sciences (Zhejiang Cancer Hospital), as well as additional patients with the same mutation from PubMed literature, to summarize the clinical features of the mutation. The association between the detection of L718Q/V and resistance to osimertinib, as well as impacts on the therapeutic process and outcome, was analyzed. We included a total of two patients diagnosed at Zhejiang Cancer Hospital and twelve patients from the literature. Of the fourteen total patients, 64.3% were male and 35.7% were female. The average age of the group was 60.2 years (range 45-72). A history of tobacco use was common among the group. In all of the cases we considered, the L718Q/V mutation was secondary to the L858R mutation. The second-generation TKI afatinib was found to provide a high disease control rate (DCR) (85.7%, 6/7) and relatively low objective response rate (ORR) (42/9%, 3/7). The median progression free survival (mPFS) for this treatment reached 2 months (1-6 months). The patients failed to benefit from chemotherapy combined with immunotherapy or other TKI medications. Due to the limited number of cases considered in this study, future studies should explore drugs that more precisely target the L718Q/V mutation of EGFR exon 18.

Third-generation EGFR and ALK inhibitors: mechanisms of resistance and management

The discoveries of EGFR mutations and ALK rearrangements as actionable oncogenic drivers in non-small-cell lung cancer (NSCLC) has propelled a biomarker-directed treatment paradigm for patients with advanced-stage disease. Numerous EGFR and ALK tyrosine kinase inhibitors (TKIs) with demonstrated efficacy in patients with EGFR-mutant and ALK-rearranged NSCLCs have been developed, culminating in the availability of the highly effective third-generation TKIs osimertinib and lorlatinib, respectively. Despite their marked efficacy, resistance to these agents remains an unsolved fundamental challenge. Both 'on-target' mechanisms (largely mediated by acquired resistance mutations in the kinase domains of EGFR or ALK) and 'off-target' mechanisms of resistance (mediated by non-target kinase alterations such as bypass signalling activation or phenotypic transformation) have been identified in patients with disease progression on osimertinib or lorlatinib. A growing understanding of the biology and spectrum of these mechanisms of resistance has already begun to inform the development of more effective therapeutic strategies. In this Review, we discuss the development of third-generation EGFR and ALK inhibitors, predominant mechanisms of resistance, and approaches to tackling resistance in the clinic, ranging from novel fourth-generation TKIs to combination regimens and other investigational therapies.

Liquid biopsy and non-small cell lung cancer: are we looking at the tip of the iceberg?

The possibility to analyse the tumour genetic material shed in the blood is undoubtedly one of the main achievements of translational research in the latest years. In the modern clinical management of advanced non-small cell lung cancer, molecular characterisation plays an essential role. In parallel, immunotherapy is widely employed, but reliable predictive markers are not available yet. Liquid biopsy has the potential to face the two issues and to increase its role in advanced NSCLC in the next future. The aim of this review is to summarise the main clinical applications of liquid biopsy in advanced non-small cell lung cancer, underlining both its potential and limitations from a clinically driven perspective.

Monitoring Somatic Genetic Alterations in Circulating Cell-Free DNA/RNA of Patients with “Oncogene-Addicted” Advanced Lung Adenocarcinoma: A Real-World Clinical Study

Liquid biopsy has advantages over tissue biopsy, but also some technical limitations that hinder its wide use in clinical applications. In this study, we aimed to evaluate the usefulness of liquid biopsy for the clinical management of patients with advanced-stage oncogene-addicted non-small-cell lung adenocarcinomas. The investigation was conducted on a series of cases—641 plasma samples from 57 patients—collected in a prospective consecutive manner, which allowed us to assess the benefits and limitations of the approach in a real-world clinical context. Thirteen samples were collected at diagnosis, and the additional samples during the periodic follow-up visits. At diagnosis, we detected mutations in ctDNA in 10 of the 13 cases (77%). During follow-up, 36 patients progressed. In this subset of patients, molecular analyses of plasma DNA/RNA at progression revealed the appearance of mutations in 29 patients (80.6%). Mutations in ctDNA/RNA were typically detected an average of 80 days earlier than disease progression assessed by RECIST or clinical evaluations. Among the cases positive for mutations, we observed 13 de novo mutations, responsible for the development of resistance to therapy. This study allowed us to highlight the advantages and disadvantages of liquid biopsy, which led to suggesting algorithms for the use of liquid biopsy analyses at diagnosis and during monitoring of therapy response.

"Sandwich" Strategy to Intensify EGFR Blockade by Concurrent Tyrosine Kinase Inhibitor and Monoclonal Antibody Treatment in Highly Selected Patients

EGFR TKIs are not curative, and targeted resistance inevitably results in therapeutic failure. Additionally, there are numerous uncommon EGFR mutations that are insensitive to EGFR TKIs, and there is a lack of clinical strategies to overcome these limitations. EGFR TKI and mAbs target EGFR at different sites, and a combination regimen for delaying/preventing resistance to targeted therapy or obtaining more intensive inhibition for uncommon mutations at cellular, animal and human levels has been explored. This review critically focuses on a combination strategy for uncommon EGFR mutation-positive NSCLC, and discuss the preclinical data, clinical implications, limitations and future prospects of the combination strategy.

Emerging strategies to overcome resistance to third-generation EGFR inhibitors

Epidermal growth factor receptor (EGFR), the receptor for members of the epidermal growth factor family, regulates cell proliferation and signal transduction; moreover, EGFR is related to the inhibition of tumor cell proliferation, angiogenesis, invasion, metastasis, and apoptosis. Therefore, EGFR has become an important target for the treatment of cancer, including non-small cell lung cancer, head and neck cancer, breast cancer, glioma, cervical cancer, and bladder cancer. First- to third-generation EGFR inhibitors have shown considerable efficacy and have significantly improved disease prognosis. However, most patients develop drug resistance after treatment. The challenge of overcoming intrinsic and acquired resistance in primary and recurrent cancer mediated by EGFR mutations is thus driving the search for alternative strategies in the design of new therapeutic agents. In view of resistance to third-generation inhibitors, understanding the intricate mechanisms of resistance will offer insight for the development of more advanced targeted therapies. In this review, we discuss the molecular mechanisms of resistance to third-generation EGFR inhibitors and review recent strategies for overcoming resistance, new challenges, and future development directions.

Resistance to TKIs in EGFR-Mutated Non-Small Cell Lung Cancer: From Mechanisms to New Therapeutic Strategies

Resistance to tyrosine kinase inhibitors (TKIs) of the epidermal growth factor receptor (EGFR) in advanced mutant Non-Small Cell Lung Cancer (NSCLC) constitutes a therapeutic challenge. This review intends to summarize the existing knowledge about the mechanisms of resistance to TKIs in the context of EGFR mutant NSCLC and discuss its clinical and therapeutic implications. EGFR-dependent and independent molecular pathways have the potential to overcome or circumvent the activity of EGFR-targeted agents including the third-generation TKI, osimertinib, negatively impacting clinical outcomes. CNS metastases occur frequently in patients on EGFR-TKIs, due to the inability of first and second-generation agents to overcome both the BBB and the acquired resistance of cancer cells in the CNS. Newer-generation TKIs, TKIs targeting EGFR-independent resistance mechanisms, bispecific antibodies and antibody-drug conjugates or combinations of TKIs with other TKIs or chemotherapy, immunotherapy and Anti-Vascular Endothelial Growth Factors (anti-VEGFs) are currently in use or under investigation in EGFR mutant NSCLC. Liquid biopsies detecting mutant cell-free DNA (cfDNA) provide a window of opportunity to attack mutant clones before they become clinically apparent. Overall, EGFR TKIs-resistant NSCLC constitutes a multifaceted therapeutic challenge. Mapping its underlying mutational landscape, accelerating the detection of resistance mechanisms and diversifying treatment strategies are essential for the management of the disease.

Optimizing Patient Outcomes Through Sequential EGFR TKI Treatment in Asian Patients With EGFR Mutation-Positive NSCLC

Patients from Asia with non-small-cell lung cancer (NSCLC) often have mutations in the epidermal growth factor receptor (EGFR) gene. While an increasing number of EGFR tyrosine kinase inhibitors (TKIs) are now available for patients with EGFR mutation-positive NSCLC, most patients inevitably develop resistance to the treatment. Evidence from clinical studies suggests that treatment outcomes and resistance mechanisms vary depending on the choice of TKI therapy in the first-line setting. Hence, it is important to develop optimal treatment sequencing strategies that can provide maximum survival benefit for the patient. In this review we present clinical evidence in Asian patients with NSCLC for various EGFR TKIs, with the goal of supporting the optimization of treatment sequencing.

Acquired Resistance to Osimertinib in EGFR-Mutated Non-Small Cell Lung Cancer: How Do We Overcome It?

Osimertinib is currently the preferred first-line therapy in patients with non-small cell lung cancer (NSCLC) with common epidermal growth factor receptor (EGFR) mutation and the standard second-line therapy in T790M-positive patients in progression to previous EGFR tyrosine kinase inhibitor. Osimertinib is a highly effective treatment that shows a high response rate and long-lasting disease control. However, a resistance to the treatment inevitably develops among patients. Understanding the secondary mechanisms of resistance and the possible therapeutic options available is crucial to define the best management of patients in progression to osimertinib. We provide a comprehensive review of the emerging molecular resistance mechanism in EGFR-mutated NSCLC pre-treated with osimertinib and its future treatment applications.

Subsequent treatments beyond progression on osimertinib in EGFR-mutated NSCLC and leptomeningeal metastases

BACKGROUND

Despite the reported efficacy of osimertinib, central nervous system (CNS) progression is still frequent in EGFR-mutated NSCLC. This study aimed to reveal site-specific resistant mechanisms to osimertinib and investigate subsequent treatments for leptomeningeal metastases (LM).

METHODS

EGFR-mutated NSCLC with LM who progressed on osimertinib were included. Molecular analysis of cerebrospinal fluid (CSF) at osimertinib progression was performed. Subsequent treatments of LM were collected and analyzed.

RESULTS

A total of 246 patients were identified. Only those with LM as a progression site on osimertinib were included (n=81). In 58 CSF-plasma pairs, more alterations were uniquely detected in CSF (77%) than in plasma (7%). These mechanisms led to 22 patients receiving matched targeted therapy. Among them, 16 (72.7%) had a clinical response. The median overall survival was 7.2 months. For non-matched therapy (n=59), the osimertinib combination had a longer median overall survival than the regimen switch in CNS-only progression (15.3 vs. 7 months, p=0.03). Finally, serial monitoring by CSF revealed the potential evolution of LM.

CONCLUSIONS

Private resistant mechanisms in CSF might match osimertinib-resistant LM for targeted therapy. Besides, continuing osimertinib with intensification strategy might prolong survival, especially for those with CNS-only progression. Prospective  exploration is needed.