Difference in central nerve system metastasis during gefitinib or erlotinib therapy in patients with EGFR-mutated non-small cell lung cancer: a retrospective study

Treatment Strategies for Non-Small Cell Lung Cancer with Common EGFR Mutations: A Review of the History of EGFR TKIs Approval and Emerging Data

The development of targeted therapies over the past two decades has led to a dramatic change in the management of EGFR-mutant non-small cell lung cancer (NSCLC). While there are currently five approved EGFR tyrosine kinase inhibitors (TKIs) for treating EGFR-mutant NSCLC in the first-line setting, therapy selection after progression on EGFR TKIs remains complex. Multiple groups are investigating novel therapies and drug combinations to determine the optimal therapy and treatment sequence for these patients. In this review, we summarize the landmark trials and history of the approval of EGFR TKIs, their efficacy and tolerability, and the role of these therapies in patients with central nervous system metastasis. We also briefly discuss the mechanisms of resistance to EGFR TKIs, ongoing attempts to overcome resistance and improve outcomes, and finalize by offering treatment sequencing recommendations.

Detection of plasma T790M mutation after the first generation EGFR-TKI resistance of non-small cell lung cancer in the real world

Background

The epidermal growth factor receptor (EGFR) gene has been identified as the driving gene of non-small cell lung cancer (NSCLC), and EGFR-tyrosine kinase inhibitor (TKI) has shown efficacy, but acquired resistance is inevitable. It has been confirmed that the secondary EGFR Thr790Met (T790M) mutation accounts for about 50% of the mechanisms of acquired resistance to EGFR-TKI. The third-generation of EGFR-TKI has significantly efficacy in advanced T790M-positive NSCLC patients. Therefore, it is necessary to detect the status of T790M in patients with acquired resistance after first generation EGFR-TKI. The objective of this study was to investigate the positive rate of plasma test T790M mutation and its relationship with different clinical characteristics, and the frequency of T790M mutation in advanced EGFR-mutant NSCLC patients with acquired resistance after firstline EGFR-TKI treatment.

Methods

Patients from a single clinical center (Taizhou hospital) were recruited prospectively from September 2017 to June 2018. The eligibility criteria of the trial included the following: (I) aged 18 years or older, histologically confirmed NSCLC stage IIIB/st and EGFR mutation positive; (II) progressive disease (PD) after first generation EGFR-TKI by RECIST v1.1, with PFS>3 months; (III) no third generation TKI treatment. All patients signed informed consent, had 10 mL of blood drawn, and were evaluated for the presence of T790M gene by amplification refractory mutation system (ARMS). The study was approved by the Ethics Committee of Taizhou Hospital (ethical batch number: 201637).

Results

A total of 189 patients were included in the analysis. The overall T790M mutation rate of plasma detection was 36.51% (69/189). The positive rate of T790M mutation after the failure of first generation EGFR-TKI treatment was not correlated with the patient’s age, sex, and the type of first generation TKI drugs. However, it was related to the mutation type of EGFR in baseline and the mode of progression according to reports by Wu et al. The frequency of T790M mutation among patients with initial exon 19 deletion mutation, exon 21 L858R point mutation, and other mutations were 45.45%, 26.19% and 33.33%, respectively. The mutation rate of T790M in 19del mutant patients was higher than that of L858R mutation and other mutations (P=0.026). The frequency of T790M mutation in local progression patients was 50% after the first generation TKI was resistant to drug treatment: in gradual progression it was 26.92%, and in dramatic progression it was 38.10%. The frequency of T790M mutation of patients with local progression was significantly higher (P=0.031).

Conclusions

The patients with EGFR mutations after the first generation of EGFR-TKI-acquired resistance of NSCLC were evaluated for their plasma EGFR mutation status, and the overall T790M mutation rate of was 36.51%. The frequency of T790M mutation with initial mutation of 19 del was higher than that of L858R mutation and other mutations, and local progression was higher than that in patients with gradual progression and dramatic progression.