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.

Allele-Specific Role of ERBB2 in the Oncogenic Function of EGFR L861Q in EGFR-Mutant Lung Cancers

INTRODUCTION

Unlike common EGFR mutations, many less common EGFR mutations remain poorly characterized in terms of oncogenic function and drug sensitivity. Here, we characterize the subset of lung adenocarcinoma harboring EGFR L861Q through both preclinical and clinical investigations.

METHODS

We reviewed clinical and genomic data from patients with EGFR-mutant lung cancer. We established cells expressing EGFR mutations and performed functional analysis of L861Q in comparison with common EGFR mutations.

RESULTS

Among the patients with lung cancer, 3.4% (47 of 1367) possess an EGFR L861Q mutation. Of the patients with L861Q, 23.4% (11 of 47) had a concurrent exon 18 mutation (typically involving G719). In vitro studies revealed that the oncogenic activity of L861Q is dependent on asymmetric dimerization. Cells expressing L861Q were less sensitive to EGFR-specific inhibitors compared with cells expressing L858R but were similarly sensitive to pan-ERBB inhibitors. In cells expressing L861Q, ERBB2 phosphorylation was markedly higher compared with cells expressing L858R, and an enhanced interaction between EGFR and ERBB2 was observed in coimmunoprecipitation studies. In addition, treatment with osimertinib enhanced expression of the antiapoptotic protein MCL1, and knockdown of ERBB2 suppressed the expression of MCL1 in L861Q, raising the possibility of differential allele-specific cross-phosphorylation of ERBB2. Moreover, compared with EGFR-specific inhibitors, pan-ERBB inhibitors exerted superior growth inhibitory effects on cells expressing compound L861Q/G719X mutations.

CONCLUSIONS

Our results suggest that ERBB2 plays a previously unrecognized role in EGFR L861Q-driven tumorigenesis, and pan-ERBB inhibitors are likely to be more effective than selective EGFR tyrosine kinase inhibitors in this setting.

Rare mutations of epidermal growth factor receptor in epidermal growth factor receptor-tyrosine kinase inhibitor-naive non-small cell lung carcinoma and the response to erlotinib therapy

Context

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are considered to be effective treatments for advanced NSCLC patients with sensitizing EGFR mutations. There are many complex and rare mutations in the EGFR gene. The efficacy of the first-generation EGFR-TKI (erlotinib) is unknown for tumors harboring rare EGFR mutations.

Aims

The purpose of this study was to investigate the clinical significance of rare EGFR mutations in EGFR-TKI-naive patients and the efficacy of erlotinib.

Settings and Design

Istanbul University, Istanbul Medical Faculty, Department of Medical Oncology, Istanbul/Turkey, and retrospective observational study.

Subjects and Methods

We retrospectively analyzed 117 non-small cell lung cancer (NSCLC) patients with EGFR mutations who had not previously used EGFR-TKIs. Exons 18-21 of EGFR were analyzed by polymerase chain reaction and subjected to direct sequencing methods.

Statistical Analysis Used

Survival estimates were calculated by the Kaplan-Meier method using SPSS 25 software (IBM SPSS, Chicago, USA).

Results

Of 117 patients who had EGFR mutations, 23 patients had rare and complex EGFR mutations. Only 9 of them were treated with erlotinib. Three patients (3.5%) with exon 20 mutations received erlotinib. Two with EGFR-p. Q787Q (SNP ID, rs10251977; c.2361G>A) synonymous mutation in exon 20 were responsive to erlotinib therapy in the second-line setting after first-line chemotherapy. To the best of our knowledge, the present two cases are the first to be reported with lung adenocarcinoma with EGFR-p. Q787Q synonymous mutation responding to erlotinib.

Conclusion

NSCLC patients harboring rare EGFR mutations generally did not show consistent or favorable responses to EGFR-TKI. We suggest that this rare synonymous mutation (EGFR-p. Q787Q) is a sensitive EGFR mutation in NSCLC.

Successful treatment of an elderly patient with an uncommon L861Q epidermal growth factor receptor mutation with low-dose afatinib: A case report

There are limited data on the clinical efficiency of afatinib in non-small cell lung cancer (NSCLC) patients with uncommon epidermal growth factor receptor (EGFR) mutations. Moreover, the efficacy and safety of afatinib in elderly patients with these mutations has not been established. Here, we describe a case of successful treatment of a patient aged >80 years with lung adenocarcinoma positive for the uncommon EGFR L861Q mutation with low-dose afatinib. An 83-year-old woman presented with cough and dyspnea. A chest computed tomography (CT) scan revealed tumors in the left upper lobe, left pleural effusion, and multiple lung metastases in both lungs. The patient was diagnosed with lung adenocarcinoma with an EGFR L861Q mutation based on cytological findings. The patient received 30 mg/day of afatinib and experienced no severe adverse events. Two weeks later, partial response was observed based on a CT scan. The results of the present case support the effectiveness and safety of low-dose afatinib in elderly patients with EGFR L861Q mutation-positive NSCLC.

EGFR L861Q Mutation in a Metastatic Solid-pseudopapillary Neoplasm of the Pancreas

Solid-pseudopapillary neoplasm of the pancreas (SPN) is a rare neoplasm that is typically indolent in nature. Surgical resection is the preferred method of treatment and often associated with a good prognosis. Local invasion and metastasis have been reported in a small subset of patients. Currently, there are limited data on the molecular mutation profile of invasive and metastatic SPN. In this report, we present the case of a 38-year-old female with a locally-invasive and unresectable SPN that, despite exhaustive chemoradiotherapy, progressed to liver metastasis. Pyrosequencing of the primary pancreatic tumor antecedent to metastasis showed an uncommon EGFR mutation at L861Q in the kinase domain of exon 21. This finding, if confirmed in additional cases of metastatic SPN, would support preoperative testing for EGFR mutation analysis to detect aggressive SPNs.

Characterization of common and rare mutations in EGFR and associated clinicopathological features in a large population of Chinese patients with lung cancer

Lung cancer with EGFR mutation is often associated pathological characteristics and good responses to EGFR tyrosine kinase inhibitors (TKIs). However, certain types of rare EGFR mutations have be linked to cases with poor response to EGFR TKIs. Therefore, extensive molecular screening and pathological characterization are essential for accurate diagnosis and selection of effective treatment plans. Although a large body of studies have established the rate of EGFR mutations as a whole entity, the rates of each individual types of mutations, especially those rare ones, have not been precisely determined in large patient populations with uniform genetic background. To address this issue, we assembled a large cohort of 456 Chinese patients with lung cancers to determine the rate of both common and rare forms of EGFR mutations and associated clinicopathological features in this retrospective study. We have found single or double EGFR mutations in 200 (43.9%) patients, including exon 19 deletions (E19del) (20%), exon 21 L858R (17.1%) and L861Q (1.5%) point mutations, exon 20 T790M (1.3%) and other mutations (1,3%), exon 18 mutations (1.3%), and double mutations (1.3%). EGFR mutation as well as its subtypes E19del, L858R, or double mutations were associated with female patients or never-smokers. In contrast, rare mutations, especially EGFR TKI resistant exon 20 mutations, were not statistically associated with any clinicopathological features, implicating that tumorigenesis driven by different EGFR mutations were mechanistically different. In summary, we have determined occurring rate of EGFR subtype mutations and demonstrated that different mutations showed different clinicopathological manifestations in lung cancer.

Sensitivities to various epidermal growth factor receptor-tyrosine kinase inhibitors of uncommon epidermal growth factor receptor mutations L861Q and S768I: What is the optimal epidermal growth factor receptor-tyrosine kinase inhibitor?

Most patients with non‐small cell lung cancer (NSCLC) harboring common epidermal growth factor receptor (EGFR) mutations, such as deletions in exon 19 or the L858R mutation in exon 21, respond dramatically to EGFR tyrosine kinase inhibitors (EGFR‐TKI), and their sensitivities to various EGFR‐TKI have been well characterized. Our previous article showed the in vitro sensitivities of EGFR exon 18 mutations to EGFR‐TKI, but little information regarding the sensitivities of other uncommon EGFR mutations is available. First, stable transfectant Ba/F3 cell lines harboring EGFR L858R (Ba/F3‐L858R), L861Q (Ba/F3‐L861Q) or S768I (Ba/F3‐S768I) mutations were created and their drug sensitivities to various EGFR‐TKI were examined. Both the Ba/F3‐L861Q and Ba/F3‐S768I cell lines were less sensitive to erlotinib, compared with the Ba/F3‐L858R cell line, but their sensitivities to afatinib were similar to that of the Ba/F3‐L858R cell line. The Ba/F3‐L861Q cell line was similarly sensitive and the Ba/F3‐S768I cell line was less sensitive to osimertinib, compared with the Ba/F3‐L858R cell line. The results of western blot analyses were consistent with these sensitivities. Next, similar experiments were also performed using the KYSE270 (L861Q) and KYSE 450 (S768I) cell lines, and their results were compatible with those of the transfectant Ba/F3 cell lines. Our findings suggest that NSCLC harboring the EGFR L861Q mutation might be sensitive to afatinib or osimertinib and that NSCLC harboring the EGFR S768I mutation might be sensitive to afatinib. Overall, afatinib might be the optimal EGFR‐TKI against these uncommon EGFR mutations.

Kinase inhibitor-responsive genotypes in EGFR mutated lung adenocarcinomas: moving past common point mutations or indels into uncommon kinase domain duplications and rearrangements

The most frequent epidermal growth factor receptor (EGFR) mutations found by traditional or comprehensive molecular profiling of lung adenocarcinomas include indels of exon 19 (the exon 19 deletion delE746_A750 being the most common) and the exon 21 L858R point mutation. The current approval labels for first line palliative gefitinib 250 mg/day, erlotinib 150 mg/day and afatinib 40 mg/day for advanced lung cancers require the presence of the aforementioned classical/sensitizing EGFR mutations. Other gefitinib, erlotinib and afatinib sensitizing mutations include exon 18 indels, G719X, exon 19 insertions, A763_Y764insFQEA, S768I and L861Q; for which off-label EGFR kinase inhibitor use is generally agreed upon by thoracic oncologists. The main biological mechanism of resistance to approved first line EGFR inhibitors is the selection/acquisition of EGFR-T790M that in itself can be inhibited by osimertinib 80 mg/day, a 3(rd) generation EGFR inhibitor that is bypassed by EGFR-C797X mutations. Another class of de novo inhibitor insensitive mutation includes EGFR exon 20 insertions. More recently, the dichotomy of only point mutations or indels explaining aberrant kinase activation of EGFR plus inhibitor response has been shattered by the discovery of uncommon (<0.5% of all EGFR mutations) genomic events involving exon 18-25 kinase domain duplications (KDD) and rearrangements (EGFR-RAD51 or EGFR-PURB). The latter lead to oncogene addiction, enhanced sensitivity to kinase inhibitors in vitro and clinical responses to approved EGFR inhibitors. The enhanced landscape of EGFR inhibitor-responsive genotypes highlights that comprehensive molecular profiling may be necessary to maximize the identification of all cases that can benefit from precision oncology.

EGFR mutations in patients with lung adenocarcinoma in southwest China: are G719S/A and L861Q more likely detected in tumors derived from smokers?

BACKGROUND

The clinical characteristics of epidermal growth factor receptor (EGFR) hotspot mutations, such as deletions in exon 19, substitution of L858R in exon 21, and mutations in exon 20, have been widely reported in nonsmall cell lung cancer. However, the clinical features of other low frequency EGFR mutations in these four exons (especially the relationship with smoking history), eg, substitutions of G719S/A/C in exon 18 and L861Q in exon 21, remain unclear. This study investigated the relationship between G719S/A/C and L861Q mutations (in exon 18 and 21) and smoking history.

METHODS

Specimens from 194 patients with lung adenocarcinoma were analyzed for EGFR mutations in exons 18-21 by high-resolution melting curve analysis and amplification refractory mutation technology to establish the relationship between G719S/A/C and L861Q mutations and smoking history.

RESULTS

Ninety-six of 194 tumors (49.5%) were confirmed to be EGFR mutation-positive. Among these mutations, 71 of 104 (68.3%) were from never smokers, six of 17 (35.3%) were from former smokers, and 19 of 73 (26.0%) were from current smokers (P < 0.001). The mutation rate in heavy smokers (5/23, 21.7%) was significantly lower than in light smokers (20/67, 29.9%) and never smokers (71/104, 68.3%, P < 0.001). Seven low frequency EGFR mutations (four substitutions of G719S, and G719 A, respectively, and three of L861Q in exon 21) were identified. Five of these mutations were derived from smokers (one former light smoker, one current heavy smoker, and three current light smokers). Four of these patients had been treated with tyrosine kinase inhibitors and all had a partial response, with median overall survival (14.5 months) and median progression-free survival (6.8 months), being longer than in patients with similarly staged lung adenocarcinoma without EGFR mutation or treatment with tyrosine kinase inhibitors (6.8 and 3.1 months, respectively, according to data from an as yet unpublished study at our institution).

CONCLUSION

This study provides further evidence that smoking status, include years of smoking and number of cigarettes smoked per day, plays an important role in EGFR mutation in patients with lung adenocarcinoma. Five of seven specimens with G719S/A or L861Q mutations coming from smokers indicates that there may be a relationship between G719S/A or L861Q mutation and smoking history. However, regardless of the influence of smoking, the effectiveness of tyrosine kinase inhibitors was satisfactory in four patients harboring G719S/A and L861Q EGFR mutation.