First-line Osimertinib for Lung Cancer With Uncommon EGFR Exon 19 Mutations and EGFR Compound Mutations.

Introduction: Up to 20% of EGFR-mutated NSCLC cases harbor uncommon EGFR mutations, including atypical exon 19 and compound mutations. Relatively little is known about the efficacy of osimertinib in these cases. Methods: Patients treated with first-line osimertinib for NSCLC with rare EGFR exon 19 (non E746_A750del) or compound mutations were included. Response assessment and time to progression were determined using Response Evaluation Criteria in Solid Tumors version 1.1 criteria. Kaplan-Meier analyses were used to estimate progression-free survival (PFS), time to treatment discontinuation (TTD), and overall survival (OS). Results: Thirty-seven patients with NSCLC harboring an atypical EGFR exon 19 mutation or compound mutation were treated with first-line osimertinib at Johns Hopkins from 2016 to 2021. Overall response rate (ORR) was 76% and median PFS, TTD, and OS were 13 months (95% confidence interval [CI]: 10-15), 22 months (95% CI: 17-32) and 36 months (95% CI, 29-48), respectively. Among atypical exon 19 mutations (n = 25), ORR was 80%, median PFS was 12 months (95% CI: 10-15), median TTD was 19 months (95% CI: 17-38), and median OS was 48 months (95% CI: 25-not reached). Compound mutations (n = 12) had an ORR of 67%, median PFS of 14 months (95% CI: 5-22), median TTD of 26 months (95% CI: 5-36), and median OS of 36 months (95% CI: 20-46). Twelve patients (32%) continued first-line osimertinib after local therapy for oligoprogression. Conclusions: Osimertinib exhibited favorable outcomes for rare EGFR exon 19 and compound mutations. The heterogeneity in outcomes among these groups of tumors with similar mutations underscores the need for continued reporting and further study of outcomes among rare variants to optimize management for each patient.

Activity of osimeRTInib in non-small-cell lung Cancer with UNcommon epidermal growth factor receptor mutations: retrospective Observational multicenter study (ARTICUNO).

BACKGROUND: Osimertinib represents the standard of care for the treatment of advanced non-small-cell lung cancer (NSCLC) harboring classical epidermal growth factor receptor (EGFR) mutations, constituting 80%-90% of all EGFR alterations. In the remaining cases, an assorted group of uncommon alterations of EGFR (uEGFR) can be detected, which confer variable sensitivity to previous generations of EGFR inhibitors, overall with lower therapeutic activity. Data on osimertinib in this setting are limited and strongly warranted. PATIENTS AND METHODS: The ARTICUNO study retrospectively evaluated data on osimertinib activity from patients with advanced NSCLC harboring uEGFR treated in 21 clinical centers between August 2017 and March 2023. Data analysis was carried out with a descriptive aim. Investigators collected response data according to RECIST version 1.1 criteria. The median duration of response, progression-free survival (mPFS), and overall survival were estimated by the Kaplan-Meier method. RESULTS: Eighty-six patients harboring uEGFR and treated with osimertinib were identified. Patients with 'major' uEGFR, that is, G719X, L861X, and S768I mutations (n = 51), had an overall response rate (ORR) and mPFS of 50% and 9 months, respectively. Variable outcomes were registered in cases with rarer 'minor' mutations (n = 27), with ORR and mPFS of 31% and 4 months, respectively. Among seven patients with exon 20 insertions, ORR was 14%, while the best outcome was registered among patients with compound mutations including at least one classical EGFR mutation (n = 13). Thirty patients presented brain metastases (BMs) and intracranial ORR and mPFS were 58% and 9 months, respectively. Amplification of EGFR or MET, TP53 mutations, and EGFR E709K emerged after osimertinib failure in a dataset of 18 patients with available rebiopsy. CONCLUSION: The ARTICUNO study confirms the activity of osimertinib in patients with uEGFR, especially in those with compound uncommon-common mutations, or major uEGFR, even in the presence of BMs. Alterations at the E709 residue of EGFR are associated with resistance to osimertinib.

Prognostic outcomes and recurrence patterns in resected stage I lung adenocarcinoma harbouring atypical epidermal growth factor receptor mutations.

OBJECTIVES: Limited data exist on the characteristics of atypical epidermal growth factor receptor (EGFR) mutations in early-stage lung cancer. Our goal was to elucidate the associations with outcomes and recurrence patterns in resected stage I lung adenocarcinoma harbouring atypical EGFR mutations. METHODS: Eligible patients between 2014 and 2019 were retrospectively identified and grouped into exon20 insertion mutations and major atypical mutations, which included G719X, L861Q and S768I. Disease-free survival (DFS) was evaluated in the entire cohort and stratified by radiologic characteristics. Recurrence patterns were investigated and compared between groups. A competing risk model was used to estimate the cumulative incidence of recurrence. RESULTS: A total of 710 patients were finally included. Among them, 289 (40.7%) patients had exon 20 insertion mutations and 421 (59.3%) patients had major atypical mutations. There was no significant difference regarding DFS (P = 0.142) between groups in the entire cohort. The interaction between mutation subtype and the presence of ground-glass opacities was significant (hazard ratio 2.00, 95% confidence interval 1.59-2.51, P < 0.001), indicating DFS between exon 20 insertion mutations and major atypical mutations may be different among subsolid and solid tumours. Survival analysis consistently revealed no significant difference in subsolid tumours (P = 0.680), but favourable DFS of exon 20 insertion mutations in solid tumours (P = 0.037). Furthermore, patients with exon 20 insertion mutations had a lower risk of developing bone metastases did those with radiologic solid tumours (Gray's test, P = 0.012). CONCLUSIONS: Exon 20 insertion mutations were correlated with favourable DFS and lower incidence of bone metastases in radiologic solid lung adenocarcinomas harbouring atypical EGFR mutations.

Treatment of Non-Small Cell Lung Cancer with Atypical EGFR Mutations.

OPINION STATEMENT: EGFR tyrosine kinase inhibitors (TKI) should always be considered when treating advanced/metastatic non-small cell lung cancer (NSCLC) with atypical EGFR mutations. The first choice of TKI depends on the specific mutation(s) present and its effect on structure and function of the EGFR protein. Afatinib is the only EGFR TKI currently FDA approved for atypical EGFR mutations and has the strongest data to support its use in PACC mutations, a subgroup of atypical EGFR mutations which includes G719X and S7681. Dacomitinib may also be an option for these mutations given similar efficacy to afatinib. In contrast, for classical-like mutations such as L861Q, osimertinib should be considered the first choice given that their behavior mimics that of the classical mutations exon 19 deletion and L858R. Osimertinib should also be utilized in the setting of a concurrent T790M mutation. Superior CNS penetrance and well managed toxicity profile may also be reasons to consider osimertinib. Given that the choice of TKI may depend on the specific mutation, it is crucial that every patient diagnosed with NSCLC undergo comprehensive sequencing to identify these mutations.

Osimertinib in NSCLC With Atypical EGFR-Activating Mutations: A Retrospective Multicenter Study.

Introduction: EGFR mutations drive a subset of NSCLC. Patients harboring the common EGFR mutations, deletion of exon 19 and L858R, respond well to osimertinib, a third-generation tyrosine kinase inhibitor. Nevertheless, the effect of osimertinib on NSCLC with atypical EGFR mutations is not well described. This multicenter retrospective study evaluates the efficacy of osimertinib among patients with NSCLC harboring atypical EGFR mutations. Methods: Patients with metastatic NSCLC treated with osimertinib, harboring at least one atypical EGFR mutation, excluding concurrent deletion of exon 19, L858R, or T790M mutations, from six U.S. academic cancer centers were included. Baseline clinical characteristics were collected. The primary end point was the time to treatment discontinuation (TTD) of osimertinib. Objective response rate by the Response Evaluation Criteria in Solid Tumors version 1.1 was also assessed. Results: A total of 50 patients with NSCLC with uncommon EGFR mutations were identified. The most frequent EGFR mutations were L861Q (40%, n = 18), G719X (28%, n = 14), and exon 20 insertion (14%, n = 7). The median TTD of osimertinib was 9.7 months (95% confidence interval [CI]: 6.5-12.9 mo) overall and 10.7 months (95% CI: 3.2-18.1 mo) in the first-line setting (n = 20). The objective response rate was 31.7% (95% CI: 18.1%-48.1%) overall and 41.2% (95% CI: 18.4%-67.1%) in the first-line setting. The median TTD varied among patients with L861Q (17.2 mo), G719X (7.8 mo), and exon 20 insertion (1.5 mo) mutations. Conclusions: Osimertinib has activity in patients with NSCLC harboring atypical EGFR mutations. Osimertinib activity differs by the type of atypical EGFR-activating mutation.

Clinicopathologic characteristics and prognostic impact of atypical EGFR mutations in completely resected lung adenocarcinoma.

INTRODUCTION: This study evaluated the clinicopathologic characteristics and prognostic impact of atypical epidermal growth factor receptor (EGFR) mutations in patients with completely resected lung adenocarcinoma (LUAD) and investigate whether adjuvant chemotherapy could benefit the survival outcomes for these subjects. MATERIAL AND METHODS: We retrospectively reviewed resected LUAD samples from 8437 patients and identified 5358 EGFR-mutated (EGFRm) cases. Of these, 4847 had classical mutations, while 511 had atypical mutations. For further survival analysis, propensity score matching, Kaplan-Meier curve, and Cox regression analyses were conducted. RESULTS: Of the 511 patients with atypical EGFRm LUAD, 131 patients had compound mutations. The frequency of exon 20 insertion (20-ins), G719X, L861Q, S768I, and de novo T790M were 30.3%, 32.7%, 21.9%, 9.2%, and 11.4%, respectively. These patients included a higher proportion of males than those with classical EGFRm LUAD. Between the 483 matched pairs of the classical and atypical EGFRm patients, no significant difference emerged in disease-free survival (DFS) (p = 0.476). Patients with the L861Q mutation had the poorest DFS among those with atypical EGFRm LUAD (p = 0.005). Cox regression analyses revealed that the L861Q mutation was an independent prognostic factor for DFS in 487 patients with solely atypical EGFRm LUAD. In addition, adjuvant chemotherapy did not improve the DFS for those patients, whether in stage IB (p = 0.638) or II-III (p = 0.505) of the disease. CONCLUSION: The L861Q mutation is an independent prognostic factor for DFS in patients with atypical EGFRm LUAD after complete resection who would not benefit from adjuvant chemotherapy regardless of disease stage.

Structure-based classification of EGFR mutations in operable pre-invasive and invasive non-small cell lung cancer: a cross-sectional study.

Background: It has been reported that the structure-based approach for defining functional groups of epidermal growth factor receptor (EGFR) mutations predicts the efficacy of EGFR inhibitors better than the traditional exon-based approach in the advanced stage. However, less is known about this structure-based classification of EGFR mutations in operable early-stage lung adenocarcinoma. Methods: Non-small cell lung cancer (NSCLC) patients with pathological stage I-III or adenocarcinoma in situ (AIS) who had EGFR mutations identified in next-generation sequencing (NGS) testing were recruited. Both exon-based and structure-based groupings of EGFR mutations were compared between the AIS and stage I-III patients using Fisher's exact test. Results: In total 1,012 patients including 66 AIS and 946 stage I-III patients were analyzed in the study. A total of 1185 EGFR mutations were identified in the 1,012 NSCLC patients, of whom 84.39% harbored a single EGFR mutation and 15.61% harbored complex EGFR mutations. As expected, L858R was more common than 19del in our population (39.33% vs. 35.67%). Interestingly, concurrent L858R and 19del mutations were identified in 9 patients (0.89%), and all these patients were diagnosed with multiple primary lung cancer. A higher percentage of atypical EGFR mutations was identified in the AIS cohort than in the stage I-III NSCLC cohort (33.33% vs. 21.66%, P=0.03). According to the structure-based classification of EGFR mutations, 86.07%, 7.11%, 5.04%, and 1.78% of the EGFR mutations were classified as classical-like, P-loop and α C-helix compressing (PACC), exon 20 insertions (Ex20ins), and T790M-like mutations, respectively. The composition of EGFR mutations was different between patients <65 and ≥65 years (P=0.0267) but similar between patients with AIS and stage I-III NSCLC (P=0.1436). However, a higher percentage of Ex20ins occurred in younger (<65 years) patients, nonsmoking patients, and patients with AIS (6.7% vs. 2.5%, P=0.003; 5.8% vs. 0.8%, P=0.0107; and 10.6% vs. 4.7%, P=0.0423, respectively). Conclusions: This large cross-sectional study delineated the structure-based classification of EGFR mutations in patients with operable NSCLC. While the traditional exon-based EGFR grouping showed difference between AIS and stage I-III NSCLC cohort, no difference was identified in the structural approach. Which approach had better prediction of targeted therapy efficacy in adjuvant settings warrants further investigation.

Treatment outcome of atypical EGFR mutations in the German National Network Genomic Medicine Lung Cancer (nNGM).

BACKGROUND: Atypical EGFR mutations occur in 10%-30% of non-small-cell lung cancer (NSCLC) patients with EGFR mutations and their sensitivity to classical epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKI) is highly heterogeneous. Patients harboring one group of uncommon, recurrent EGFR mutations (G719X, S768I, L861Q) respond to EGFR-TKI. Exon 20 insertions are mostly insensitive to EGFR-TKI but display sensitivity to exon 20 inhibitors. Clinical outcome data of patients with very rare point and compound mutations upon systemic treatments are still sparse to date. PATIENTS AND METHODS: In this retrospective, multicenter study of the national Network Genomic Medicine (nNGM) in Germany, 856 NSCLC cases with atypical EGFR mutations including co-occurring mutations were reported from 12 centers. Clinical follow-up data after treatment with different EGFR-TKIs, chemotherapy and immune checkpoint inhibitors were available from 260 patients. Response to treatment was analyzed in three major groups: (i) uncommon mutations (G719X, S7681, L861Q and combinations), (ii) exon 20 insertions and (iii) very rare EGFR mutations (very rare single point mutations, compound mutations, exon 18 deletions, exon 19 insertions). RESULTS: Our study comprises the largest thus far reported real-world cohort of very rare EGFR single point and compound mutations treated with different systemic treatments. We validated higher efficacy of EGFR-TKI in comparison to chemotherapy in group 1 (uncommon), while most exon 20 insertions (group 2) were not EGFR-TKI responsive. In addition, we found TKI sensitivity of very rare point mutations (group 3) and of complex EGFR mutations containing exon 19 deletions or L858R mutations independent of the combination partner. Notably, treatment responses in group 3 (very rare) were highly heterogeneous. Co-occurring TP53 mutations exerted a non-significant trend for a detrimental effect on outcome in EGFR-TKI-treated patients in groups 2 and 3 but not in group 1. CONCLUSIONS: Based on our findings, we propose a novel nNGM classification of atypical EGFR mutations.