Complex Epidermal Growth Factor Receptor Mutations Research Articles

Abstract C025: Trial in progress: First-in-human study of BBT-207 in advanced non-small cell lung cancer harboring EGFR mutation after treatment with EGFR TKI

Abstract Background: There is a high unmet need for an effective therapy for the treatment of non-small cell lung cancer (NSCLC) following osimertinib or other 3rd generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) failure, especially when resistance is driven by the occurrence of the C797S mutation. BBT-207 is a fourth-generation EGFR inhibitor. Preclinically BBT-207 has shown activity against treatment-emergent complex EGFR mutations containing T790M and/or C797S as well as drug-naïve mutants providing a possibility to overcome resistance to prior TKIs. Activity to intracranial lesions is also anticipated from animal models. Methods: Study BBT207-ONC-001 is an open-label, phase 1/2 study evaluating safety, tolerability, pharmacokinetic profile, pharmacodynamic characterization, and preliminary antitumor activity of BBT-207 monotherapy in approximately 92 patients with EGFR-mutant NSCLC. It consists of 3 phases: Phase 1a (dose escalation), phase 1b (recommended phase 2 dose selection), and phase 2 (dose expansion). Key eligibility criteria include patients ≥18 years of age with advanced stage and refractory NSCLC with an activating EGFR mutation, documented partial response, complete response, or durable stable disease after treatment of an EGFR TKI, and previous treatment with all standard therapeutic options and at least one third-generation EGFR TKI. There is no limit on the number of previous treatments received. Phase 1a requires confirmation that the tumor harbors a classical EGFR mutation (19Del or L858R), and phase 1b and phase 2 require confirmation that the tumor or the blood harbors complex EGFR mutations containing C797S. Patients with asymptomatic brain metastases who are on stable dose of corticosteroid are eligible. Primary endpoints are to determine recommended dose range (RDR) which is defined between the minimal reproducibly active dose, and the maximum tolerated dose or maximum administered dose and to characterize the overall safety and tolerability of BBT-207 (phase 1a); to determine the recommended phase 2 dose (phase 1b); to evaluate preliminary antitumor activity with objective response rate (phase 2). Phase 1a dose escalation will be guided by Bayesian logistic regression model. The safety monitoring committee will determine RDR and two recommended dose levels (RDs) within the RDR to be explored in phase 1b. In phase 1b, up to 20 patients will be randomized to each of the two RDs. At the end of phase 1b, a futility test will be performed in the dose level to be treated with the RP2D using Bayesian analysis. Phase 2 will be a non-randomized, open-label phase with up to 20 patients. Patients may receive treatment until disease progression or unacceptable toxicity. Treatment continuation beyond progression will be allowed if potential benefits are justified. Investigational new drug application was cleared by the U.S. FDA. Patient enrollment will begin in approximately August 2023 in the U.S. and Republic of Korea. Clinical trial information: NCT05920135. Citation Format: NaEun Jeon, Alexander Spira, Douglas Orr, Lyudmila Bazhenova, Misako Nagasaka, Jin Seok Ahn, Dong-Wan Kim, Yu Jung Kim, Jimin Cho, Agnes Jung, Eunsoo Jung, Chul-Won Kim, Taiguang Jin, Yong-Hee Lee, Sang-Yoon Lee. Trial in progress: First-in-human study of BBT-207 in advanced non-small cell lung cancer harboring EGFR mutation after treatment with EGFR TKI [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C025.

Association of smoking status with non-small cell lung cancer patients harboring uncommon epidermal growth factor receptor mutation.

Uncommon epidermal growth factor receptor (EGFR) mutations include single and complex mutations. However, the association of the smoking status of patients with uncommon and complex EGFR mutations remains unclear. This retrospective study evaluates the spectrum of uncommon EGFR mutations and investigates the influence of smoking status on the frequency of various uncommon EGFR mutations using a multi-institutional medical database. Between 2010 and 2019, 5,608 non-small cell lung cancer (NSCLC) patients were analyzed. EGFR mutations were detected in 3,155 (56.3%) patients. Among the 399 (12.6%) patients with uncommon mutations, 198 had single uncommon and 201 complex mutations, including 87 exon 20 insertions, 79 de novo T790M, 70 complex common, and 52 complex uncommon mutations. For comparison, we also included 402 patients with common EGFR mutations. The percentage of ever-smokers was significantly higher in patients with uncommon EGFR mutations than in patients with common EGFR mutations (25.8% vs. 17.4%, p = 0.005). Furthermore, the percentage of ever-smokers was higher in those with a complex mutation than in those with a single uncommon mutation (30.3% vs. 21.2%, p = 0.040). Among patients carrying uncommon EGFR mutations, ever-smokers had significantly more complex uncommon EGFR mutations than never-smokers (22.3% vs. 9.8%, p = 0.002). Among patients carrying G719X, L861Q, and S768I, ever-smokers tended to have complex EGFR mutations more frequently than never-smokers (64.7% vs. 28.7%, 50.0% vs. 18.7%, 88.9% vs. 81.2%, respectively). Our study demonstrates not only a comprehensive spectrum of uncommon EGFR mutations, but also a positive relationship between smoking status and uncommon EGFR mutation frequency, especially complex uncommon EGFR mutations. The results suggest that smoking contributes to the development of complex EGFR mutations.

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

BackgroundIt 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.MethodsNon-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.ResultsIn 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).ConclusionsThis 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.

Efficacy of dacomitinib in patients with non-small cell lung cancer carrying complex EGFR mutations: a real-world study.

BackgroundDacomitinib is a first-line treatment for patients with non-small cell lung cancer (NSCLC) harboring common epidermal growth factor receptor (EGFR) mutations; however, clinical evidence of its activity on NSCLC with complex EGFR mutations is limited.MethodsPatients harboring complex (common mutations co-existing with uncommon mutations), or common (comparison cohort) EGFR mutations, who were treated with dacomitinib, were retrospectively evaluated in the Chinese National Cancer Center and the China PLA hospital between August 2019 and August 2021.ResultsIn total, 72 patients with NSCLC harboring complex (C+U group, n=18) or common (C group, n=54) EGFR mutations and being treated with dacomitinib were enrolled. In the C+U group, 16 cases (88.9%) harbored L858R mutations co-existing with uncommon mutations located from exon 18 to exon 25 of EGFR (mostly E709X), and two cases harbored exon 19 deletion co-existing with G724S or K754E. Among the 15 evaluable patients, the objective response rate (ORR) was 40% (6/15), and the disease control rate (DCR) was 73.3% (11/15). The median progression-free survival (PFS) was 7.5 months [95% confidence interval (CI), 4.4–10.6 months]. Except for the application line of dacomitinib (P=0.039), no significant statistical differences were found in other characteristics and adverse events between the two groups. The Kaplan-Meier method revealed no significant differences in PFS (P=0.889) and overall survival (OS) (P=0.703). However, the stratified analysis found worse PFS in the C+U group than that observed in the C group when receiving 1st and ≥3rd line dacomitinib treatment, while its OS was worse than that of group C when receiving ≥3rd line treatment. Furthermore, in a multivariate analysis, complex mutation status was an independent prognostic factor for OS (P=0.038) in the entire cohort.ConclusionsThis study indicated a worse response and prognosis of patients with NSCLC harboring complex EGFR mutations than those harboring common EGFR mutations when treated with dacomitinib. Further studies and data are needed to confirm this conclusion.

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

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. 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). 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 group1. Based on our findings, we propose a novel nNGM classification of atypical EGFR mutations.

Mutation Spectrum of EGFR From 21,324 Chinese Patients With Non-Small Cell Lung Cancer (NSCLC) Successfully Tested by Multiple Methods in a CAP-Accredited Laboratory.

Genotyping epidermal growth factor receptor (EGFR) gene in patients with advanced non-small cell lung cancers (NSCLC) is essential for identifying those patients who may benefit from targeted therapies. Systemically evaluating EGFR mutation detection rates of different methods currently used in clinical setting will provide valuable information to clinicians and laboratory scientists who take care of NSCLC patients. This study retrospectively reviewed the EGFR data obtained in our laboratory in last 10 years. A total of 21,324 NSCLC cases successfully underwent EGFR genotyping for clinical therapeutic purpose, including 5,244 cases tested by Sanger sequencing, 13,329 cases tested by real-time PCR, and 2,751 tested by next-generation sequencing (NGS). The average EGFR mutation rate was 45.1%, with 40.3% identified by Sanger sequencing, 46.5% by real-time PCR and 47.5% by NGS. Of these cases with EGFR mutations identified, 93.3% of them harbored a single EGFR mutation (92.1% with 19del or L858R, and 7.9% with uncommon mutations) and 6.7% harbored complex EGFR mutations. Of the 72 distinct EGFR variants identified in this study, 15 of them (single or complex EGFR mutations) were newly identified in NSCLC. For these cases with EGFR mutations tested by NGS, 65.3% of them also carried tumor-related variants in some non-EGFR genes and about one third of them were considered candidates of targeted drugs. NGS method showed advantages over Sanger sequencing and real-time PCR not only by providing the highest mutation detection rate of EGFR but also by identifying actionable non-EGFR mutations with targeted drugs in clinical setting.

Mutation spectrum of EGFR in 21,324 patients with non-small cell lung cancer successfully tested by multiple platforms in a CAP-accredited laboratory.

e13637 Background: Genotyping epidermal growth factor receptor ( EGFR) gene in patients with advanced non-small cell lung cancers (NSCLC) is essential to identify those patients who may benefit from targeted treatments. However, the testing methodology is still a puzzle for many clinicians. This study retrospectively reviewed the EGFR data from testing patients with NSCLC in our laboratory in 10 years. Methods: A total of 21,324 NSCLC cases successfully underwent EGFR genotyping in our laboratory for clinical therapeutic purpose, including 5,244 cases tested by Sanger sequencing, 13,329 cases tested by real-time PCR, and 2,751 tested by next generation sequencing-NGS. Results: 54.6%, 20% and 2.3% samples were recorded with tumor cell content (TCC) of &lt; 40%, &lt; 20% and 1% respectively. The average EGFR mutation rate was 45.1%, with 40.3% identified by Sanger sequencing, 46.5% by real-time PCR and 47.5% by NGS. Comparable EGFR mutation rates were observed in cases with 1%-20% TCC from real-time PCR and NGS platforms. In these cases with EGFR mutations, 93.3% of them carried a single EGFR mutation (92.1% with a classical mutation as 19del or L858R, and 7.9% with an uncommon mutation) and 6.7% harbored complex EGFR mutations. 65.3% of the cases carrying EGFR mutations identified by NGS also have tumor related variants in other genes. 26.5% more cases were found to have oncogenic driver mutations with therapeutic significance beyond EGFR by NGS. Conclusions: NGS may be the most optimal methodology to detect EGFR mutations in patients with NSCLC compared with Sanger sequencing and real-time PCR platforms from accuracy and comprehensiveness aspects, but some other issues, such as Turn Around Time (TAT), still should be considered in clinical practice.

Complex EGFR mutations with secondary T790M mutation confer shorter osimertinib progression-free survival and overall survival in advanced non-small cell lung cancer

ObjectivesOsimertinib is active against epidermal growth factor receptor (EGFR) T790M-mutated non-small cell lung cancer (NSCLC). However, its efficacy against complex EGFR mutations with T790M has not been evaluated. Materials and methodsIn order to detect complex EGFR mutations, we consecutively sequenced cancer tissues by RNA reverse transcription polymerase chain reaction. Patients with advanced NSCLC with activating EGFR mutation and secondary T790M who received osimertinib were enrolled. Patients’ clinicopathologic characteristics, prior treatment details, and osimertinib treatment outcomes were analyzed. ResultsTotally, 165 sequenced patients were analyzed. Eleven (7%) of them had complex EGFR mutations with T790M. The osimertinib response rate was 27%. They had a shorter progression-free survival (PFS) (median, 2.9 and 9.7 months, p < 0.001) and overall survival (OS) (median, 17.8 and 31.0 months, p = 0.01) than patients with a single EGFR mutation with T790M. After osimertinib failure, seven patients received rebiopsy with molecular analysis. Four lost the T790M, two transformed to small cell and one acquired C797S. Moreover, taking the median as the demarcation, patients received shorter prior EGFR tyrosine kinase inhibitor (TKI) treatment duration had a shorter osimertinib PFS (median, 7.3 and 13.8 months, p < 0.001) and OS (median, 21.5 and 36.7 months, p = 0.003). Multivariate Cox regression analysis confirmed complex EGFR mutations and prior EGFR TKI treatment duration were independent factors for osimertinib PFS and OS. ConclusionsComplex EGFR mutations and shorter prior EGFR TKI treatment duration may confer shorter osimertinib PFS and OS in advanced NSCLC with secondary T790M mutation.

487P - Afatinib versus gefitinib or erlotinib in first-line setting for Malaysia patients with EGFR mutant advanced lung adenocarcinoma

BackgroundAfatinib is an irreversible second-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) while gefitinib or erlotinib are reversible first-generation EGFR-TKIs. MethodsA retrospective analysis of patients with EGFR mutant advanced lung adenocarcinoma receiving first-line afatinib versus gefitinib or erlotinib at University Malaya Medical Centre from 1st January 2015 to 31th December 2018. ResultsOf 113 patients, 24 (21.2%) received afatinib, 63 (55.8%) received gefitinib and 26 (23.0%) received erlotinib in first-line setting. Their demographic and clinical characteristics are shown in the table. Afatinib was used significantly more frequently in patients with rare or complex EGFR mutations (p = 0.005), and more often in patients with symptomatic brain metastases. The median progression-free survival (mPFS) of patients treated with afatinib (13.1 months) was longer than that of patients treated with gefitinib (10.9 months) or erlotinib (7.8 months) (p = 0.479). Patients receiving afatinib had consistently longer PFS than patients receiving gefitinib for the first 17 months and erlotinib for the first 20 months. The overall response rate was higher in patients on afatinib (75.0%) than those on gefitinib (63.5%) or erlotinib (53.8%). There was no difference in the disease control rate. Three patients (2.7%) had severe side-effects while on EGFR-TKI. Of two patients on afatinib, one had grade-3 diarrhea while another had grade 3 stomatitis, rash and paronychia. One patient had grade 3 rash on gefitinib.Table487P Clinical characteristic of 113 patients on first-line EGFR-TKITableCharacteristics, No (%)Afatinib (24)Gefitinib (63)Erlotinib (26)p-valueSymp brain metsNo Yes17 (70.8) 7 (29.2)53 (84.1) 10 (15.9)22 (84.6) 4 (15.4)0.181EGFR subtype19 del 21 L858R Rare/complex16 (66.7) 2 (8.3) 6 (25.0)39 (61.9) 20 (31.7) 4 (6.3)22 (84.6) 3 (11.5) 1 (3.8)0.005Side-effectgrade 1-2 grade 322 (91.7) 2 (8.3)62 (98.4) 1 (1.6)26 (100) 00.007Objective responseYes No18 (75.0) 6 (25.0)40 (63.5) 23 (36.5)14 (53.8) 12 (46.2)0.298Disease controlYes No23 (95.8) 1 (4.2)59 (93.7) 4 (6.3)24 (92.3) 2 (7.7)0.872Median PFSMonths Event, No. (%)13.1 19 (79.2)10.9 49 (77.8)7.8 19 (73.1)0.479 ConclusionsPatients receiving first-line afatinib demonstrated longer mPFS than those on first-line gefitinib or erlotinib. The lack of statistical significance in this study is because of the small number of patients treated with afatinib, more frequent rare or complex EGFR mutations and more symptomatic brain metastases among afatinib treated patients. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.

P2.14-47 Real-World Multicenter Experience of First-line Afatinib in Patients with EGFR-Mutant Advanced Non-Small Cell Lung Cancer

Afatinib is an irreversible, second-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) that has been shown to be more potent than platinum doublet chemotherapy as well as the first-generation EGFR-TKI. This study aimed to look into the efficacy, side-effects and resistance mechanisms of first-line afatinib in the real-world setting. This is a multicenter observational study of Malaysian patients with EGFR-mutant advanced non-small cell lung cancer (NSCLC) started on first-line afatinib from 1st October 2014 to 30th April 2018. Of 85 patients analyzed, EGFR mutations harbored by the tumors included exon 19 deletion in 80.0%, exon 21 L858R point mutation in 12.9%, and rare or complex EGFR mutations in 7.1%. Among the 85 patients, 18.8% had an ECOG performance status of 2-4, 29.4% had symptomatic brain metastases and 17.6% had abnormal organ function. Afatinib 40 mg or 30 mg once daily was the most common starting and maintenance doses. Only one-tenth of patients experienced severe side-effects and none had grade 4 toxicities. The objective response rate was 76.5% while the disease control rate was 95.3%. At the time of analysis, 56 (65.9%) patients had experienced disease progression (PD) with a median progression-free survival (mPFS) of 12.2 months (95% CI, 8.9-15.5 months). Only 12.5% of the PD patients developed new symptomatic brain metastases. Multivariate analysis demonstrated only patients with exon 19 deletion had significantly longer mPFS than those with rare or complex EGFR mutations (13.5 versus 9.0 months, HR, 0.31; 95% CI, 0.11-0.84; p = 0.021). The overall survival data was not mature. Of the patients who experienced PD while on afatinib, 55.3% were investigated for acquired resistance mechanisms. Exon 20 T790M mutation was detected in 42.0% of these patients. Afatinib is an effective first-line treatment for patients with EGFR-mutant advanced NSCLC with good response and disease control rates as well as long PFS even in patients with unfavorable clinical characteristics. The side-effects of afatinib were manageable and acquired T790M mutation was a common mechanism causing treatment failure.

Rare epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer.

Epidermal growth factor receptor (EGFR) mutations are the second most common oncogenic driver event in non-small cell lung cancer (NSCLC). Classical activating mutations (exon 19 deletions and the L858R point mutation) comprise the vast majority of EGFR mutations and are well defined as strong predictors for good clinical response to EGFR tyrosine kinase inhibitors (EGFRi). However, low frequency mutations including point mutations, deletions, insertions and duplications occur within exons 18–25 of the EGFR gene in NSCLC and are associated with poorer responses to EGFRi. Despite an increased uptake of more sensitive detection methods to identify rare EGFR mutations in patients, our understanding of the biology of these rare EGFR mutations is poor compared to classical mutations. In particular, clinical data focused on these mutations is lacking due to their rarity and challenges in trial recruitment, resulting in an absence of effective treatment strategies for many low frequency EGFR mutations. In this review, we describe the structural and mechanistic features of rare EGFR mutations in NSCLC and discuss the preclinical and clinical evidence for EGFRi response for individual rare EGFR mutations. We also discuss EGFRi sensitivity for complex EGFR mutations, and conclude by offering a perspective on the outstanding questions and future steps required to make advances in the treatment of NSCLC patients that harbour rare EGFR mutations.

Real-world experience of first-line afatinib in patients with EGFR-mutant advanced NSCLC: a multicenter observational study

BackgroundThis study aimed to evaluate the efficacy, side-effects and resistance mechanisms of first-line afatinib in a real-world setting.MethodsThis is a multicenter observational study of first-line afatinib in Malaysian patients with epidermal growth factor receptor (EGFR)-mutant advanced non-small cell lung cancer (NSCLC). Patients’ demographic, clinical and treatment data, as well as resistance mechanisms to afatinib were retrospectively captured. The statistical methods included Chi-squared test and independent t-test for variables, Kaplan-Meier curve and log-rank test for survival, and Cox regression model for multivariate analysis.ResultsEighty-five patients on first-line afatinib from 1st October 2014 to 30th April 2018 were eligible for the study. EGFR mutations detected in tumors included exon 19 deletion in 80.0%, exon 21 L858R point mutation in 12.9%, and rare or complex EGFR mutations in 7.1% of patients. Among these patients, 18.8% had Eastern Cooperative Oncology Group performance status of 2–4, 29.4% had symptomatic brain metastases and 17.6% had abnormal organ function.Afatinib 40 mg or 30 mg once daily were the most common starting and maintenance doses. Only one-tenth of patients experienced severe side-effects with none having grade 4 toxicities. The objective response rate was 76.5% while the disease control rate was 95.3%. At the time of analysis, 56 (65.9%) patients had progression of disease (PD) with a median progression-free survival (mPFS) of 14.2 months (95% CI, 11.85–16.55 months). Only 12.5% of the progressed patients developed new symptomatic brain metastases. The overall survival (OS) data was not mature. Thirty-three (38.8%) patients had died with a median OS of 28.9 months (95% CI, 19.82–37.99 months). The median follow-up period for the survivors was 20.0 months (95% CI, 17.49–22.51 months).Of patients with PD while on afatinib, 55.3% were investigated for resistance mechanisms with exon 20 T790 M mutation detected in 42.0% of them.ConclusionsAfatinib is an effective first-line treatment for patients with EGFR-mutant advanced NSCLC with a good response rate and long survival, even in patients with unfavorable clinical characteristics. The side-effects of afatinib were manageable and T790 M mutation was the most common resistance mechanism causing treatment failure.

Concurrent Driver Gene Mutations as Negative Predictive Factors in EGFR Positive Non-Small Cell Lung Cancer

Background: Tyrosine kinase inhibitors (TKIs) are clinically effective in non-small cell lung cancer (NSCLC) patients harboring epidermal growth factor receptor (EGFR) oncogene mutations. However, the genetic factors other than EGFR mutations that may predict the disease progression and efficacy of TKI treatment needs to be define. Methods: Four hundred and twenty three consecutive patients with advanced NSCLC and EGFR 19del or 21L858R mutations were retrospectively screened. A total of 71 patients whose progression free survivals (PFS) were longer than 24 months or shorter than 6 months were included and stratified into two groups. Pretreatment specimens of tumor tissue were collected and next generation sequencing (NGS) was performed. Genetic background discrepancy was analyzed in the two groups. Findings: Sensitive EGFR mutations of 19del or 21 L858R were detected by NGS in all of the 71 patients. The 21L858R mutation was the major EGFR mutation type. Complex EGFR mutations were found in 22 (31%) patients. The most frequent accompany somatic mutations were TP53 (42/59%), followed by RB1 (14%), MAPK2K (8%), and ERBB2 (7%). Concurrent resistant mutation of T790M was found in both groups while ALK fusion, MET amplification, and BRAF V600E were only found in short PFS group. The T790M ratio to EGFR mutation was higher in short PFS group. Patients in short PFS group had significantly more resistant mutations than patients in long PFS group (P=0*018). The number of contaminate somatic mutations, the number of EGFR pathway related mutation and tumor mutation burden (TMB) were not significant different between the two groups. Interpretion: Preexisting driver gene mutations and a high T790M ratio to EGFR mutation were most important negative predictive factors of TKI therapy in EGFR-mutated patients receiving TKI treatment. This study also highlights the importance of exploring resistance genomic alterations as well as driver mutations before the initiation of EGFR-TKIs. Funding: National Natural Science Foundation of China (Grant No. 81702292). Declaration of Interest: No potential conflicts of interest were disclosed. Ethical Approval: This study was approved by the Peking Union Medical College Hospital review board.

140PD Complex epidermal growth factor receptor (EGFR) mutations and responses to tyrosine kinase inhibitors (TKIs) in advanced lung adenocarcinomas

Background: Two or more different epidermal growth factor receptor (EGFR) mutations can be detected within a single tumor sample, which represents complex mutations. However, the frequency and efficacy of tyrosine kinase inhibitor (TKI) treatments for patients harboring these mutations are unknown. Methods: From January 2011 to January 2017, patients diagnosed with EGFR mutation were screened. The effectiveness of TKIs in patients with complex mutations was retrospectively analyzed. Results: A total of 16,840 subjects were screened, with 5898 positive patients. 187 patients (3.2% of all EGFR mutant patients) had complex EGFR mutations with 95 of advanced lung adenocarcinoma patients were treated with TKIs. The objective response rate (ORR) for patients who had Del-19 + 21L858R (Group A, n = 27), Del-19/21L858R + atypical mutations (Group B, n = 28), double atypical mutations (Group C, n = 20) and complex mutations with primary drug-resistant pattern (Group D, n = 20) were 72.7%, 54.2%, 66.7% and 15.0%, respectively. Median progression free survival (PFS) in the four groups were 18.2 months (95% CI, 12.0 months to 24.4 months), 10.1 months (95% CI, 6.5 months to 13.7 months), 11.1 months (95% CI, 6.8 months to 15.4 months) and 1.4 months (95% CI, 0.2 months to 2.5 months), respectively. Conclusions: These results suggest on the largest sample size that EGFR–TKI therapy is effective in patients with Del-19 + 21L858R, Del-19/21L858R + atypical mutations and double atypical mutations, but less effective in patients with primary drug–resistant pattern. Patients with the Del-19 + 21L858R mutations may therefore benefit more from treatment with first–generation TKIs. Legal entity responsible for the study: Bo Zhang Funding: Has not received any funding Disclosure: All authors have declared no conflicts of interest.

Complex epidermal growth factor receptor mutations and their responses to tyrosine kinase inhibitors in previously untreated advanced lung adenocarcinomas.

Two or more different epidermal growth factor receptor (EGFR) mutations can be detected within a single tumor sample, which represents complex mutations. However, the frequency and efficacy of tyrosine kinase inhibitor (TKI) treatments for patients harboring these mutations are unknown. From January 2011 to January 2017, patients diagnosed with EGFR mutations were screened. The effectiveness of TKIs in patients with complex mutations was retrospectively analyzed. A total of 16,840 subjects were screened, and there were 5898 positive patients. One hundred eighty-seven patients (3.2% of all patients with EGFR mutations) had complex EGFR mutations, and 51 of the patients with advanced adenocarcinoma were treated with TKIs as a first-line treatment. The objective response rates for patients who had Del-19+21L858R mutations (n = 15), Del-19/21L858R+atypical mutations (n = 16), double atypical mutations (n = 8), and complex mutations with a primary drug-resistant pattern (n = 12) were 75.0%, 60.0%, 71.0%, and 8.3%, respectively. The median progression-free survival times for the 4 groups were 18.2 months (95% confidence interval [CI], 10.6-25.9 months), 9.7 months (95% CI, 3.3-15.8 months), 9.6 months (95% CI, 3.3-19.0 months), and 1.4 months (95% CI, 0.4-2.3 months), respectively. These results from the largest sample size suggest that EGFR-TKI therapy is effective in patients with Del-19+21L858R mutations, Del-19/21L858R+atypical mutations, and double atypical mutations but is less effective in patients with a primary drug-resistant pattern. Patients with the Del-19+21L858R mutations may, therefore, benefit more from treatment with first-generation TKIs. Cancer 2018;124:2399-406. © 2018 American Cancer Society.

Uncommon &lt;em&gt;EGFR&lt;/em&gt; mutations in cytological specimens of 1,874 newly diagnosed Indonesian lung cancer patients

PurposeWe aimed to evaluate the distribution of individual epidermal growth factor receptor (EGFR) mutation subtypes found in routine cytological specimens.Patients and methodsA retrospective audit was performed on EGFR testing results of 1,874 consecutive cytological samples of newly diagnosed or treatment-naïve Indonesian lung cancer patients (years 2015–2016). Testing was performed by ISO15189 accredited central laboratory.ResultsOverall test failure rate was 5.1%, with the highest failure (7.1%) observed in pleural effusion and lowest (1.6%) in needle aspiration samples. EGFR mutation frequency was 44.4%. Tyrosine kinase inhibitor (TKI)-sensitive common EGFR mutations (ins/dels exon 19, L858R) and uncommon mutations (G719X, T790M, L861Q) contributed 57.1% and 29%, respectively. Approximately 13.9% of mutation-positive patients carried a mixture of common and uncommon mutations. Women had higher EGFR mutation rate (52.9%) vs men (39.1%; p<0.05). In contrast, uncommon mutations conferring either TKI responsive (G719X, L861Q) or TKI resistance (T790M, exon 20 insertions) were consistently more frequent in men than in women (67.3% vs 32.7% or 69.4% vs 30.6%; p<0.05). Up to 10% EGFR mutation–positive patients had baseline single mutation T790M, exon 20 insertion, or in coexistence with TKI-sensitive mutations. Up to 9% patients had complex or multiple EGFR mutations, whereby 48.7% patients harbored TKI-resistant mutations. One patient presented third-generation TKI-resistant mutation L792F simultaneously with T790M.ConclusionRoutine diagnostic cytological techniques yielded similar success rate to detect EGFR mutations. Uncommon EGFR mutations were frequent events in Indonesian lung cancer patients.

Efficacy of EGFR tyrosine kinase inhibitors in non-small cell lung cancer patients harboring different types of EGFR mutations: A retrospective analysis.

With the development of molecular pathology, many types of epidermal growth factor receptor (EGFR) mutations have been identified. The efficacy of EGFR tyrosine kinase inhibitors (EGFR-TKIs) in non-small cell lung cancer (NSCLC) patients with different types of EGFR mutations, especially in patients with single rare mutations or complex mutations (co-occurrence of two or more different mutations), has not been fully understood. This study aimed to examine the efficacy of EGFR-TKIs in NSCLC patients with different types of EGFR mutations. Clinical data of 809 NSCLC patients who harbored different types of EGFR mutations and treated from January 2012 to October 2016 at Renmin Hospital and Zhongnan Hospital, Wuhan, were retrospectively reviewed. The clinical characteristics of these patients and the efficacy of EGFR-TKIs were analyzed. Among these patients, 377 patients had only the EGFR del-19 mutation, 362 patients the EGFR L858R mutation in exon 21, 33 patients single rare mutations and 37 patients complex mutations. Among these 809 patients, 239 patients were treated with EGFR-TKIs. In all the 239 patients, the disease control rate (DCR) was 93.7% with two patients (0.2%) achieving complete response (CR), the median progression free survival (PFS) was 13.0 months (95% confidence interval [CI], 11.6-14.4 months), and the median overall survival (OS) was 55.0 months (95% CI, 26.3-83.7 months). Subgroup analysis revealed that the DCR in patients harboring single rare or complex mutations of EGFR was significantly lower than in those with del-19 or L858R mutation (P<0.001). Patients with classic mutations (del-19 and/or L858R mutations) demonstrated longer PFS (P<0.001) and OS (P=0.017) than those with uncommon mutations (single rare and/or complex mutations). Furthermore, the patients with single rare mutations had shorter median OS than in those with other mutations. Multivariate Cox regression analysis identified that the type of EGFR mutations was an independent risk factor for PFS (hazard ratio [HR]=0.308, 95% CI, 0.191-0.494, P<0.001) and OS (HR=0.221, 95% CI, 0.101-0.480, P<0.001). The results suggest that the single rare or complex EGFR mutations confer inferior efficacy of EGFR-TKIs treatment to the classic mutations. The prognosis of the single rare EGFR mutations is depressing. EGFR-TKIs may be not a good choice for NSCLC patients with single rare mutations of EGFR. Further studies in these patients with uncommon mutations (especially for the patients with single rare mutations) are needed to determine a better precision treatment.

NSCLC Patients Harbouring Rare or Complex EGFR Mutations Are More Often Smokers and Might Not Benefit from First-Line Tyrosine Kinase Inhibitor Therapy

Background: Generally, tyrosine kinase inhibitor (TKI) therapy is recommended in first-line treatment of patients with advanced non-small cell lung cancer (NSCLC) harbouring a classic epidermal growth factor receptor (EGFR) mutation. However, the response of patients with rare or complex EGFR mutations to TKI treatment is not predictable, nor is the prognosis for such patients. Objectives: In cases of rare or complex EGFR mutations, the right approach to therapy remains challenging. That is why we sought to analyse the characteristics as well as the prognosis and the response to TKI treatment of patients with rare or complex EGFR mutations. Patients and Methods: 343 NSCLC patients tested for EGFR mutation at a German lung cancer centre were analysed for age, gender, and smoking status as well as for the mutation status. For 12 patients with rare and complex mutations, response to TKI treatment was described. Results: 282 of all patients had a wild-type EGFR, whereas 61 harboured an EGFR mutation. 32 of these were classic mutations, followed by 16 rare and 7 complex mutations. EGFR mutations were significantly more frequent in women. Patients with rare or complex mutations were significantly more often smokers compared to those with classic EGFR mutations. Furthermore, rare and complex mutations were less responsive to TKI therapy. Conclusion: Patients with rare or complex EGFR mutations differ from those with classic mutations in terms of smoking status and response to TKIs. As these mutations may not respond well to TKI therapy, first-line TKIs should not be automatically chosen based on the sole presence of an EGFR mutation.

Clinical characteristics of patients with non-small cell lung cancers harboring anaplastic lymphoma kinase rearrangements and primary lung adenocarcinoma harboring epidermal growth factor receptor mutations.

Echinoderm microtubule associated protein like 4-anaplastic lymphoma kinase (EML4-ALK) gene rearrangements and epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) have been intensively studied. The objective of this study was to determine the clinicopathological characteristics in genotype-specific subsets of patients with NSCLC to help ensure the optimal identification of patients whose tumors harbor these two driver mutations. The incidence of ALK rearrangements was investigated in 763 NSCLC specimens by immunohistochemistry using a D5F3 antibody, and EGFR mutations were assessed by amplification refractory mutation system (ARMS) in 222 patients with lung adenocarcinoma. Of these, 73 (9.6%) were detected as being ALK-positive; this designation was associated with young age, female gender, never-smokers, lymph node metastasis, and poor tumor differentiation, but not with histology. EGFR mutations were identified in 102 (45.9%) of 222 adenocarcinoma samples, and were more frequent in females and never-smokers. No difference in age was observed. Specifically, we identified several cases of complex EGFR mutations, and concomitant EGFR mutations and ALK rearrangements. These results suggest that young women and never-smokers are at risk for ALK rearrangement. We also identified concomitant mutations of EGFR and rearrangements of ALK in this study.

Including Total EGFR Staining in Scoring Improves EGFR Mutations Detection by Mutation-Specific Antibodies and EGFR TKIs Response Prediction

Epidermal growth factor receptor (EGFR) is a novel target for therapy in subsets of non-small cell lung cancer, especially adenocarcinoma. Tumors with EGFR mutations showed good response to EGFR tyrosine kinase inhibitors (TKIs). We aimed to identify the discriminating capacity of immunohistochemical (IHC) scoring to detect L858R and E746-A750 deletion mutation in lung adenocarcinoma patients and predict EGFR TKIs response. Patients with surgically resected lung adenocarcinoma were enrolled. EGFR mutation status was genotyped by PCR and direct sequencing. Mutation-specific antibodies for L858R and E746-A750 deletion were used for IHC staining. Receiver operating characteristic (ROC) curves were used to determine the capacity of IHC, including intensity and/or quickscore (Q score), in differentiating L858R and E746-A750 deletion. We enrolled 143 patients during September 2000 to May 2009. Logistic-regression-model-based scoring containing both L858R Q score and total EGFR expression Q score was able to obtain a maximal area under the curve (AUC: 0.891) to differentiate the patients with L858R. Predictive model based on IHC Q score of E746-A750 deletion and IHC intensity of total EGFR expression reached an AUC of 0.969. The predictive model of L858R had a significantly higher AUC than L858R intensity only (p = 0.036). Of the six patients harboring complex EGFR mutations with classical mutation patterns, five had positive IHC staining. For EGFR TKI treated cancer recurrence patients, those with positive mutation-specific antibody IHC staining had better EGFR TKI response (p = 0.008) and longer progression-free survival (p = 0.012) than those without. In conclusion, total EGFR expression should be included in the IHC interpretation of L858R. After adjusting for total EGFR expression, the scoring method decreased the false positive rate and increased diagnostic power. According to the scoring method, the IHC method is useful to predict the clinical outcome and refine personalized therapy.