Performance of different methods for detecting T790M mutation in the plasma of patients with advanced NSCLC after developing resistance to first-generation EGFR-TKIs in a real-world clinical setting

Abstract

Several approaches to the detection of T790M mutations in patient plasma or tissue samples have been implemented to date. The present study was designed to assess the ability of different technologies to detect the T790M mutation in plasma samples and to evaluate the relative rates of re-biopsy and subsequent patient management in a clinical setting. Data from patients with advanced NSCLC who visited the Department of Respiratory Medicine of the First Hospital Affiliated to Wenzhou Medical University between December 2014 and July 2018 were retrospectively collected. Following re-biopsy, these patients were evaluated for the presence of the T790M mutation via next-generation sequencing (NGS), amplification refractory mutation system or Roche Cobas z480 (Cobas) analyses of tissue samples. T790M mutation status in tumor tissue samples was calculated as a standard reference used to establish the sensitivity, specificity and concordance of three circulating tumor DNA detection approaches, including NGS, droplet digital PCR (ddPCR) and super amplification refractory mutation system (SuperARMS). Subsequent patient management was also recorded. In total, 287 patients with advanced non-small cell lung cancer were evaluated, of whom 55.4% (159/287) underwent tissue re-biopsy, 76.7% (122/159) underwent sequencing analysis of plasma and/or tissue samples, and 59.0% (72/122) were found to harbor the T790M mutation. The rates of plasma sample T790M detection via NGS, ddPCR and SuperARMS were 60.0, 59.3 and 60.0%, respectively. Only 32 patients with T790M mutations (44.4%, 32/72) were treated with third-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), while 19 continued treatment with first-generation TKIs, 13 underwent chemotherapy, 1 switched to treatment with anlotinib, 4 succumbed to pericardial or brain metastases, and 3 were lost to follow-up. Additionally, 2 patients exhibited histological transformation from adenocarcinoma to small cell lung cancer, while 17/97 patients who were evaluated for brain metastases during treatment exhibited intracranial progression. Of these, 8 patients had been treated with osimertinib. In this study of a real-world clinical setting, fewer patients than expected underwent re-biopsy and gene sequencing. Of the tools available for the analysis of plasma samples, NGS exhibited the highest sensitivity and concordance with the results of tissue-based T790M detection strategies. It was additionally found that only a subset of patients harboring the T790M mutation were ultimately treated using third-generation EGFR-TKIs.

Keywords: T790M; acquired resistance; epidermal growth factor receptor tyrosine kinase inhibitors; non-small cell lung cancer; re-biopsy.

Figure 1

Flowchart of the study design. EGFR-TKI, epidermal growth factor receptor tyrosine kinase inhibitor; NGS, next-generation sequencing; ddPCR, droplet digital PCR; SuperARMS, super amplification refractory mutation system.

Figure 2

Kaplan-Meier curve analysis demonstrated that patients with and without T790M did not exhibit statistically significant differences in median PFS-1 (P<0.001). PFS, progression-free survival; PFS-1, time from initiation of treatment with first-generation epidermal growth factor receptor tyrosine kinase inhibitors to the first documentation of progressive disease.

Figure 3

Kaplan-Meier curve analysis demonstrated that patients harboring T790M mutation treated with osimertinib had a longer PFS-2 compared with the subgroup treated with chemotherapy or first-generation TKIs (P<0.001). PFS, progression-free survival; PFS-2, time from the initiation of sequential therapy until the date of objective disease progression or death; TKIs, tyrosine kinase inhibitors.

Figure 4

Distribution of the159 patients subjected to tissue and plasma re-biopsy. NGS, next-generation sequencing; ddPCR, droplet digital PCR; SuperARMS, super amplification refractory mutation system.