Response to Tyrosine Kinase Inhibitors in Lung Adenocarcinoma with the Rare Epidermal Growth Factor Receptor Mutation S768I: a Retrospective Analysis and Literature Review

Current management of uncommon EGFR mutations in non-small cell lung cancer

Epidermal growth factor receptor (EGFR) mutations are frequently implicated in non-small cell lung cancer (NSCLC). Though these typically involve exon 19 in-frame deletions or L858R mutations in exon 21, uncommon EGFR mutations comprise 10-15 % of all EGFR mutations. These most frequently include G719X mutations in exon 18, L861Q mutations in exon 21, S768I mutations in exon 20, and in-frame insertions and/or duplications in exon 20. It is crucial to understand these distinct variants and their specific responses to active treatment options to optimize care. In this review, we discuss these uncommon mutations in depth and dissect the current literature regarding their treatment outcomes and subsequent evidence-based management guidelines.

An epidermal growth factor receptor compound mutation of L858R with S768I in advanced non-small-cell lung cancer: a case report

BACKGROUND

In the current treatment landscape for non-small cell lung cancers, epidermal growth factor receptor-tyrosine kinase inhibitors have emerged as a well-established treatment option for patients with advanced or metastatic disease. This is particularly true for those with commonly occurring epidermal growth factor receptor mutations. However, the therapeutic efficacy of these agents for so-called rare epidermal growth factor receptor mutations, and in particular those characterized by a high degree of complexity, such as double mutations, remains a subject of clinical uncertainty.

CASE PRESENTATION

In this context, we present the case of a 64-year-old man of Moroccan descent, a lifelong non-smoker, diagnosed with metastatic non-small cell lung cancer characterized by a complex epidermal growth factor receptor mutation encompassing L858R and S768I. The patient subsequently underwent afatinib-based treatment, showing notable clinical results. These included a remarkable overall survival of 51 months, with a median progression-free survival of more than 39 months.

CONCLUSIONS

This case report is a compelling testimony to the evolving therapeutic landscape of non-small cell lung cancers, providing valuable insight into the potential therapeutic efficacy of epidermal growth factor receptor-tyrosine kinase inhibitors in the realm of rare and complex epidermal growth factor receptor mutations.

Molecular epidemiology and clinical characteristics of epidermal growth factor receptor mutations in NSCLC: A single-center experience from India

Background

The genetic profiling of non-small cell lung cancer (NSCLC) has contributed to the discovery of actionable targetable mutations, which have significantly improved outcomes in disease with poor prognosis. Molecular epidemiological data of driver mutations in Indian populations have not been extensively elaborated compared to western and eastern Asian NSCLC populations. This study assessed the prevalence and clinical outcomes of EGFR (epidermal growth factor receptor) mutations among the Indian NSCLC cohort in South India.

Patients and Methods

Retrospective analysis of 2,003 NSCLC patients who had undergone EGFR mutational analysis from 2013 to 2020 was performed. Clinical analysis was performed for 141 patients from 2013 to 2017 using Kaplan-Meier and Chi-square methods. Descriptive and survival statistics were performed using IBM SPSS Statistics for Windows, Version 23.0. Armonk, NY: IBM Corp.

Results

EGFR-sensitizing mutations were detected in 41.6% (834/2003) in the study cohort with compound mutations detected in 7.55% (63/834) of EGFR-positive cases. A significant relationship with regard to female gender and EGFR mutation status (P <.001) was observed. Exon 18 G719X (8.7%) mutations and exon 20 T790M point mutation (3.1%) were the most frequently isolated uncommon EGFR mutations. In the clinical cohort, EGFR mutations were detected at a significantly higher prevalence in females (P =0.002) and never-smokers (P < 0.001). EGFR mutation demonstrated a significant relationship with regard to brain metastasis (P = 0.011). EGFR mutated individuals had significantly longer median overall survival compared to EGFR wild type (26 months vs. 12 months, P = 0.044).

Conclusion

We reports the highest number of EGFR mutation analysis performed from India and mutational analysis indicated a loco-regional variation in India with regard to EGFR mutation frequency and its subtypes.

Heterogeneous distribution of EGFR mutation in NSCLC: Case report

Background

We herein report the case of a patient with advanced lung adenocarcinoma who presented a heterogeneous distribution of EGFR mutation.

Case report

A 74-year-old Moroccan male former smoker was diagnosed with advanced lung adenocarcinoma, harboring S768I exon 20 substitution mutation confirmed by Real Time PCR and Pyrosequencing, but not detected by direct sequencing despite 70% of tumor cells. The present report describes a case of minor histologic intratumoral heterogeneity with heterogeneous distribution of EGFR mutation.

Conclusion

Both sensitivity and specificity of molecular methods can provide evidence of intratumoral heterogeneity, which may explain the mismatch between the validation of oncology biomarkers and predicting therapeutic response to targeted therapy.

Successful treatment of a patient with NSCLC carrying uncommon compound EGFR G719X and S768I mutations using osimertinib: A case report

The discovery of epidermal growth factor receptor (EGFR) somatic mutations and the availability of tyrosine kinase inhibitors (TKIs) as targeted therapies have altered the therapeutic prospects of advanced non-small-cell lung cancer (NSCLC). G719X and S768I are uncommon mutations, and they often exist as compound mutations. A few reports have described the efficacy of first- and second-generation EGFR-TKIs. However, the efficacy of osimertinib in patients with these uncommon compound mutations is unknown. In this study, we reported the postoperative outcome of a patient with NSCLC and uncommon compound EGFR G719X and S768I mutations. After postoperative recurrence, the patient was treated with osimertinib, and an excellent and long-lasting clinical response was achieved. The patient has taken osimertinib for 31.0 months and exhibited a partial response, and her follow-up is ongoing.

Clinical Benefit of Tyrosine Kinase Inhibitors in Advanced Lung Cancer with EGFR-G719A and Other Uncommon EGFR Mutations

The optimal management of advanced non-small cell lung cancer (NSCLC) with noncanonical epidermal growth factor receptor (EGFR) mutations (i.e., exon 19 deletion and exon 21 L858R) is constrained by the heterogeneous behavior of individual uncommon mutations and limited prospective clinical data in this setting. Despite encouraging results with osimertinib from a recently published phase II trial from South Korea, afatinib remains the only currently approved drug for patients with tumors harboring uncommon EGFR mutations (i.e., S768I, L861Q, and/or G719X). When used at the standard dose of 40 mg daily, afatinib is associated with significant rates of treatment-related adverse events, leading to frequent dose reductions and treatment discontinuations. We report a case of a woman with advanced NSCLC harboring EGFR-G719A mutation treated with afatinib (at an off-label pulse dose strategy that merits further evaluation in prospective studies) with sustained partial response for 20 months with manageable expected toxicities. Subsequent disease progression was mediated by off-target pan-EGFR inhibitor (including osimertinib)-resistant KRAS mutation and not by acquisition of EGFR-T790M. We further present the current state of evidence in the literature behind use of first-, second-, and third-generation tyrosine kinase inhibitors and summarize the evolving spectrum of activity ascribed to osimertinib (and newer EGFR inhibitors with a more favorable therapeutic window and intracranial penetration) in this population of patients with advanced NSCLC and uncommon EGFR mutations. KEY POINTS: Uncommon EGFR mutations characterize a heterogeneous group of patients with advanced non-small cell lung cancer (NSCLC). Afatinib is the only currently U.S. Food and Drug Administration-approved drug for management of advanced NSCLC with uncommon EGFR mutations (S768I, L861Q, and/or G719X). Afatinib treatment at 40 mg daily is associated with high rates of adverse events and dose reductions; alternative strategies including pulse intermittent dosing should be evaluated prospectively. Osimertinib (with favorable safety profile and intracranial penetration) has shown promising results in this population in a phase II trial from South Korea; additional trials are ongoing.

Understanding EGFR heterogeneity in lung cancer

The advances in understanding the inherited biological mechanisms of non-small cell lung cancer harbouring epidermal growth factor receptor (EGFR) mutations led to a significant improvement in the outcomes of patients treated with EGFR tyrosine kinase inhibitors. Despite these clinically impressive results, clinical results are not always uniform, suggesting the need for deepening the molecular heterogeneity of this molecularly defined subgroup of patients beyond the clinical and biological surface.The availability of tissue and blood-based tumour genotyping allows us to improve the understanding of molecular and genetic intratumor heterogeneity, driving the measurement of clonal evaluation in patients with lung cancer carrying EGFR mutations. Genetic diversification, clonal expansion and selection are highly variable patterns of genetic diversity, resulting in different biological entities, also a prerequisite for Darwinian selection and therapeutic failure.Such emerging pieces of evidence on the genetic diversity, including adaptive and immunomodulated aspects, provide further evidence for the role of the tumour microenvironment (TME) in drug-resistance and immune-mediated mechanisms. Matching in daily clinical practice, the detailed genomic profile of lung cancer disease and tracking the clonal evolution could be the way to individualise the further target treatments in EGFR-positive disease. Characterising the tumour and immune microenvironment during the time of the cancer evaluation could be the way forward for the qualitative leap needed from bench to bedside. Such a daring approach, aiming at personalising treatment selection in order to exploit the TME properties and weaken tumour adaptivity, should be integrated into clinical trial design to optimise patient outcome.

Response to tyrosine kinase inhibitors in lung adenocarcinoma with the rare epidermal growth factor receptor mutation S768I and G724S: A case report and literature review

Mutations in the epidermal growth factor receptor (EGFR) are drivers of a subset of lung cancers. In recent years, the treatment of non-small cell lung cancer (NSCLC), especially with EGFR inhibitors, has made rapid progress, and the median progression-free survival (PFS) of patients with EGFR gene-sensitive mutations has been significantly prolonged. However, the response effect of some uncommon EGFR mutations to tyrosine kinase inhibitors (TKIs) remains unclear. Here, we present a patient with multiple EGFR mutations that highlights tumor heterogeneity leading to a mixed molecular response to targeted drugs and emphasizes the complexity of EGFR-driven lung cancer. He received chemotherapy and molecular-targeted treatment including icotinib, afatinib, osimertinib and afatinib + osimertinib. In conclusion, patients with lung adenocarcinoma harboring the EGFR S768I and G724S mutations appear less sensitive to icotinib than patients with sensitive EGFR. However, the patient in our report benefited from treatment with afatinib. Here, we hope to provide information for the treatment of rare and compound mutations in patients.

The significance of epidermal growth factor receptor uncommon mutations in non-small cell lung cancer: A systematic review and critical appraisal

Uncommon epidermal growth factor receptor (EGFR) mutations collectively account for 10% of EGFR mutations, harboring heterogeneous molecular alterations within exons 18-21 with clinically variable responses to EGFR tyrosine kinase inhibitors (TKIs) in advanced Non-Small Cell Lung Cancer (NSCLC) patients. In addition, with the introduction of different NGS gene approach an improvement of EGFR mutations detection was reported. Today, no specific studies have prospectively evaluated uncommon sensitizing mutations in detail and no firm standard of care has been established in the first-line setting. The aim of this comprehensive review is to critically consider the clinical role of uncommon EGFR mutations highlighting the results of several in vitro and in vivo studies, which singly evaluated the sensitivity of uncommon mutations to currently European of Medicines Agency (EMA)-approved EGFR TKIs in cell lines, xenograft models and humans, in order to obtain a practical guide for refining the clinical decision-making process.

Osimertinib for Patients With Non-Small-Cell Lung Cancer Harboring Uncommon EGFR Mutations: A Multicenter, Open-Label, Phase II Trial (KCSG-LU15-09)

PURPOSE

Approximately 10% of patients with epidermal growth factor receptor (EGFR) mutation-positive non-small-cell lung cancer (NSCLC) harbor uncommon mutations. Here, we report the efficacy and safety of osimertinib in patients with NSCLC harboring uncommon EGFR mutations.

PATIENT AND METHODS

This was a multicenter, single-arm, open-label, phase II study in Korea. Patients with histologically confirmed metastatic or recurrent NSCLC harboring EGFR mutations other than the exon 19 deletion, L858R and T790M mutations, and exon 20 insertion were eligible for the study. The primary end point of objective response rate was assessed every 6 weeks by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Secondary end points were progression-free survival, overall survival, duration of response, and safety.

RESULTS

Between March 2016 and October 2017, 37 patients were enrolled. All were evaluable except one patient who withdrew consent after starting treatment. Median age was 60 years, and 22 (61%) were male. Among patients, 61% received osimertinib as first-line therapy. The mutations identified were G719X (n = 19; 53%), followed by L861Q (n = 9; 25%), S768I (n = 8; 22%), and others (n = 4; 11%). Objective response rate was 50% (18 of 36 patients; 95% CI, 33% to 67%). Median progression-free survival was 8.2 months (95% CI, 5.9 to 10.5 months), and median overall survival was not reached. Median duration of response was 11.2 months (95% CI, 7.7 to 14.7 months). Adverse events of any grade were rash (n = 11; 31%), pruritus (n = 9; 25%), decreased appetite (n = 9; 25%), diarrhea (n = 8; 22%), and dyspnea (n = 8; 22%), but all adverse events were manageable.

CONCLUSION

Osimertinib demonstrated favorable activity with manageable toxicity in patients with NSCLC harboring uncommon EGFR mutations.

Clinical outcome of treatment of metastatic non-small cell lung cancer in patients harboring uncommon EGFR mutation

Background

Uncommon epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) is a rare subset of NSCLC. The aim of this study was to investigate the prevalence, characteristics, and clinical outcomes of metastatic NSCLC harboring uncommon EGFR mutation at Thailand’s largest national tertiary hospital. The secondary objective was to compare treatment efficacy between EGFR-tyrosine kinase inhibitor (EGFR-TKI) and chemotherapy.

Methods

This retrospective chart review included patients that were tested for EGFR-mutation NSCLC during 2014–2018. Patient demographic and clinical data, treatment data, and outcome data were collected and analyzed.

Results

Of the 681 patients that were evaluated for EGFR mutation, 317 (47.0%) had EGFR-mutant NSCLC, and 28 (8.8%) of those harbored uncommon EGFR mutations. The median follow-up was 19.1 months. History of tobacco use was reported in 50% of patients. The most common single mutation among uncommon EGFR was exon 20 insertion (n = 6), followed by L861Q (n = 5) and G719X (n = 4). Thirteen (46%) patients had compound mutations. One hundred percent of male patients with G719X mutation were smokers. Sixteen of 28 patients were treated with EGFR-TKI. Most received first-generation EGFR-TKI, and 29% were treated with chemotherapy alone. The objective response rate was 37.5% in the EGFR-TKI group. Median progression-free survival (PFS) in the EGFR-TKI group was 10.2 months. Median PFS among the 8 patients in the chemotherapy group that received first-line platinum doublet was 6.5 months. Three-year overall survival (OS) among 28 patients was 34%. Three-year OS was significantly better in patients treated with EGFR-TKI.

Conclusions

Uncommon EGFR mutations was detected in 8.8% of EGFR-mutant NSCLC. Exon 20 insertion was the most common mutation, and 50% of patients had history of tobacco use. First- or second-generation EGFR-TKI demonstrated greater OS benefit than platinum-doublet chemotherapy among patients harboring uncommon EGFR-mutant NSCLC. Survival outcomes were comparable to those reported from previous large cohort studies.

Treatment of uncommon EGFR mutations in non-small cell lung cancer: new evidence and treatment

Sensitizing mutations in epidermal growth factor receptor (EGFR) are associated with positive responses to anti-EGFR-targeted therapy, leading to a new era of treatment for non-small cell lung cancer (NSCLC). Exon 19 deletions and exon 21 L858R substitutions are the most common mutations, accounting for approximately 90% mutations in NSCLC; these are termed classic mutations and result in high sensitivity to tyrosine kinase inhibitors (TKIs). Other EGFR mutations are termed uncommon EGFR mutations, of which G719X, S768I, L861Q, exon 20 insertions, and complex mutations are the most frequent. G719X, S768I, and L861Q are point mutations and those that exist with complex mutations are sensitive to first-generation TKIs. A prospective analysis demonstrated that afatinib, a second-generation TKI, led to a better prognosis in some patients with NSCLC compared to first-generation TKIs. Chemotherapy used to be the traditional choice for patients carrying exon 20 insertions; however, with the development of novel targeted drugs, the role of chemotherapy is changing. Tremendous progress has also been made in clinical trials on immunotherapy treatment of uncommon EGFR mutations. The treatment for patients with NSCLC harboring uncommon EGFR mutations remains a subject of debate and the sensitivity of uncommon EGFR mutations to TKIs is still unclear. Here, we summarized recent data in the literature and provide an overview of the clinical characteristics, incidence, and outcomes of patients harboring G719X, S768I, L861Q, exon 20 insertions, and complex mutations who were treated with TKIs, chemotherapy, or immunotherapy.

Clinical Impact of Rare and Compound Mutations of Epidermal Growth Factor Receptor in Patients With Non-Small-Cell Lung Cancer

BACKGROUND

Standard therapy of advanced non-small-cell lung cancer harboring an activating mutation in the epidermal growth factor receptor (EGFR) gene is treatment with tyrosine kinase inhibitors (TKI). However, for rare and compound mutations of the EGFR gene, the clinical evidence of TKI therapy is still unclear.

PATIENTS AND METHODS

A total of 2906 lung cancer samples were analyzed for EGFR mutations during routine analysis between 2010 and 2017. The samples have been investigated by Sanger sequencing and since 2014 by next-generation sequencing.

RESULTS

We detected EGFR mutations in 408 specimens (14%). Among these, we found 41 samples with rare and 22 with compound mutations. In these 63 samples, 56 different rare EGFR mutations occurred. Information about the clinical outcome was available for 37. Among those with rare mutations, only one patient harboring the mutation p.G874D had disease that responded to first-generation TKI therapy. In contrast, the disease of all patients with compound mutations responded to first- or second-generation TKI therapy. Furthermore, we collected data on clinical relevance regarding TKI therapy from different databases and from an additional literature search, and only found data for 36 of the 56 detected rare mutations.

CONCLUSION

Information about the clinical outcome of patients with rare and compound EGFR mutations remains limited. At present, second- and third-generation TKIs are available, which may represent new treatment strategies for these patients. Therefore, it is becoming increasingly important to maintain databases concerning rare EGFR mutations.

First-generation EGFR tyrosine kinase inhibitor therapy in 106 patients with compound EGFR-mutated lung cancer: a single institution's clinical practice experience

Background

The antitumour efficacy of tyrosine kinase inhibitors (TKIs) in lung cancer patients with compound epidermal growth factor receptor (EGFR) mutations has not been resolved. Our study summarizes a single institutional experience of first-generation TKI therapy for lung cancers with compound EGFR mutations.

Methods

A total of 106 consecutive patients with tumours bearing compound EGFR mutations were identified between January 2012 and May 2016; all patients received first-generation TKI therapy. Deletions in exon 19 and the L858R point mutation in exon 21 were considered common mutations; T790M was considered separately because of its association with TKIs resistances. Any other mutation was defined as a rare mutation. Patients were divided as follows: double common mutations (group A); common plus T790M mutations (group B); common plus rare mutations (group C); double rare mutations (group D); and rare plus T790M mutations (group E). A separate group of 115 consecutive patients with a single common mutation was created for comparative analysis (group F).

Results

The frequency of patients with compound EGFR was 2.9% (114/3925) and their response rate to first-generation TKIs was 50.9%, which was not significantly different from group F (67.0%, P = 0.088). The progression-free survival (PFS) of the 106 patients receiving TKI therapy was worse than that of group F (median, 9.1 vs. 13.0 months, respectively; P < 0.001). The PFS of the compound mutation group was shorter than that of the single common mutation group (median, 10.1 months in group A, P = 0.240; 9.1 months in group B, P < 0.001; 9.6 months in group C, P = 0.010; 6.5 months in group D, P = 0.048; 5.4 months in group E, P = 0.017). Patients with a co-occurring mutation in exon 20 (excluding T790M) exhibited significantly worse PFS than the patients with other compound mutations or with a single common mutation (median, 6.5 vs. 9.1 vs. 13.0 months, respectively, P = 0.002).

Conclusions

There was significant heterogeneity among the compound EGFR mutations and their response to first-generation TKIs. Individualized treatment in clinical practice should be considered for each case.

Effectiveness of afatinib after ineffectiveness of gefitinib in an advanced lung adenocarcinoma patient with a single EGFR exon 20 S768I mutation: a case report

Epidermal growth factor receptor-tyrosine kinase inhibitors have improved progression-free survival and overall survival in non-small-cell lung cancer (NSCLC) patients with sensitive mutations. However, response of uncommon mutation to epidermal growth factor receptor-tyrosine kinase inhibitors is still unclear. S768I is one of the uncommon mutations. A female patient with advanced NSCLC with a single S768I mutation achieved effectiveness from afatinib after showing no response to gefitinib. The patient had progression-free survival after taking afatinib for 6 months, and her follow-up is continuing. It suggests that afatinib may be a more effective treatment for NSCLC patients with a single S768I mutation, compared to first-generation tyrosine kinase inhibitors.

Uncommon mutations in epidermal growth factor receptor and response to first and second generation tyrosine kinase inhibitors: A case series and literature review

Epidermal growth factor receptor (EGFR) is the most common driver gene involved in non small cell lung cancer (NSCLC) growth, being found in approximately 10-15% of Caucasian and 40% of Asian patients. A wide variety of pathogenic mutations, deletions, insertions and duplications have been described in EGFR exons 18-21. The presence of the most common among them (e.g. exon 21 L851R and exon 19 deletions) is associated to response to first and second generation EGFR tyrosine kinase inhibitors (TKIs), which have demonstrated clear superiority over chemotherapy in terms of both progression free survival (PFS) and overall survival (OS) in all treatment lines. However, scarcity of data exists in literature about the response of rarer EGFR alterations to first and second generation TKIs, most works consisting in sporadic case reports and small case series. In this review we aim to discuss the available evidence about this topic, in order to derive suggestions for clinical practice. Furthermore, we report seven cases of patients with lung tumors harboring uncommon EGFR mutations, treated in our Institution with first or second generation TKIs.

Uncommon EGFR mutations in a cohort of Chinese NSCLC patients and outcomes of first-line EGFR-TKIs and platinum-based chemotherapy

Objective

Data on the clinical activity of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in patients with non-small-cell lung cancer (NSCLC) and uncommon EGFR mutations remain insufficient. This study aimed to investigate the effect of first-line EGFR-TKIs or platinum-based chemotherapy in NSCLC patients with uncommon EGFR mutations.

Methods

We retrospectively enrolled 504 patients with EGFR-mutant NSCLC. The clinical characteristics and treatment outcomes were collected and compared between patients with common and uncommon EGFR-mutant NSCLC.

Results

Seventy patients (13.9%) harboring uncommon EGFR mutations were included. Thirty of these patients received EGFR-TKIs and 40 received platinum-based chemotherapy as first-line therapy. The objective response rate (ORR) and median progression-free survival (mPFS) of patients treated with TKIs in the uncommon mutation group was significantly inferior to that in the common mutation group (ORR: 23.3% vs. 51.8%, P=0.003; mPFS: 7.1 vs. 10.9 months, P<0.001). In the uncommon group, mPFS was similar between first-line EGFR-TKIs treatment and platinum-based chemotherapy (7.1vs. 6.1 months, P=0.893). In patients with EGFR G719X or L861Q mutations, the mPFS was longer in the first-line EGFR-TKIs treatment group than in the chemotherapy group, but the difference was not statistically significant (G719X: 8.2 vs. 5.8 months, P=0.061; L861Q: 7.6 vs. 4.1 months, P=0.872). Multivariate analyses identified adenocarcinoma (P=0.003) as the independent predictive factor for PFS in patients with uncommon EGFR mutations who were treated with first-line EGFR-TKIs.

Conclusions

The current study demonstrated that the effect of first-line EGFR-TKIs was similar to that of platinum-based chemotherapy in patients with uncommon EGFR-mutant NSCLC. Adenocarcinoma was the independent predictive factor for PFS in uncommon EGFR-mutant NSCLC patients treated with first-line EGFR-TKIs.