A sensitive and practical method to detect the T790M mutation in the epidermal growth factor receptor

Abstract

Abstract. The current study aimed to develop a method to rapidly, sensitively and practically screen for the epidermal growth factor receptor (EGFR) T790M mutation. This method combines an allele-specific competitive blocker (ACB) with a TaqMan quantitative polymerase chain reaction (PCR) amplification refractory mutation system (ARMS) in a one-step reaction. Using a mimic of a human genomic DNA panel containing serially diluted mutant alleles, the performance efficacy of this method was assessed. Using this method, the EGFR T790M mutation was detected in tyrosine kinase inhibitor (TKI)-naïve samples obtained from 27 non-small cell lung cancer (NSCLC) patients with EGFR-activating mutations. The association between de novo T790M mutations and the clinical benefit of EGFR-TKI treatment was also analysed. The sensitivity of this method was as low as 0.01%. In the samples from the 27 NSCLC patients, this method identified 6 mutant patients (22.2%), which was higher than the detection rate with scorpion ARMS (0.0%). No clinical variables were associated with the occurrence of a de novo T790M mutation. The median progression-free survival time in the TKI-naïve patients with a T790M mutation was shorter that that of patients without the mutation, but the difference was not significant (3.2 vs. 19.5 months, respectively; P=0.256). The median overall survival time in the groups with or without T790M mutation also did not significantly differ (10 vs. 20 months, respectively; P=0.689). Overall, the ACB-ARMS PCR method could be useful for detecting the EGFR T790M mutation in clinical samples that contain only a small number of mutant alleles. The clinical significance of a de novo T790M mutation should be further investigated.

EGFR T790M Mutation in TKI-Naïve Clinical Samples: Frequency, Tissue Mosaicism, Predictive Value and Awareness on Artifacts

“…Importantly, Costa et al [32] also demonstrated that EGFR T790M status does not influence PFS in patients receiving chemotherapy. In contrast to other studies [30,31,32,34,44,45], Fujita et al [26] reported a trend towards increased duration of response to TKI in T790M-mutated patients. Although the results of meta-analyses support the predictive role of mosaic T790M mutation in determining TKI response, it is necessary to acknowledge that the frequency of the T790M detection in the mentioned studies ranged from 22% to 80% [33,47,48].…”

“…Although the results of meta-analyses support the predictive role of mosaic T790M mutation in determining TKI response, it is necessary to acknowledge that the frequency of the T790M detection in the mentioned studies ranged from 22% to 80% [33,47,48]. Furthermore, given that highly sensitive detection of mosaic T790M allele and collection of EGFR-mutated patients with sufficient treatment follow-up are challenging, the majority of available clinical studies are of modest size [31,32,44,45]. There could also be a publication bias, as small investigations reporting ‘positive' results have better chances to be reported than the ‘negative' ones [49,50].…”

“…The majority of studies showed a tendency to shorter PFS in patients with this mutation [30,31,32,34,44,45]. In support of a biological role of mosaic T790M mutations, Costa et al [32] and Rosell et al [46] observed that low-abundance T790M alleles are characteristic only for lung cancer with EGFR TKI-sensitizing mutations but are uncommon for EGFR wt and KRAS-mutated tumors (see online supplemental materials for these articles).…”

Meta-analysis of the impact of de novo and acquired <em>EGFR</em> T790M mutations on the prognosis of patients with non-small cell lung cancer receiving EGFR-TKIs

“…Recently, researchers have also explored the relationship between prognosis and pretreatment T790M mutation 25–32. Increasing evidence has indicated that T790M may exist at a low frequency within the tumor cells before EGFR-TKI treatment and may become the dominant clone only after drug selection pressure of EGFR-TKI treatment 25.…”

“…Increasing evidence has indicated that T790M may exist at a low frequency within the tumor cells before EGFR-TKI treatment and may become the dominant clone only after drug selection pressure of EGFR-TKI treatment 25. Although reliable and widely accepted methods for detecting EGFR T790M mutation status have not yet been established, some researchers have attempted to detect T790M mutation before EGFR-TKI treatment using different assays with sensitivities ranging from 0.001% to 0.4% 25–32. This meta-analysis explored the influences of acquired T790M mutation following EGFR-TKI treatment and de novo T790M mutation prior to EGFR-TKI treatment on survival and prognosis in patients with advanced NSCLC who had activating EGFR mutations.…”