Independent prognostic value of ultra-sensitive quantification of tumor pre-treatment T790M subclones in EGFR mutated non-small cell lung cancer (NSCLC) treated by first/second generation TKI, depends on variant allele frequency (VAF): Results of the Fren

T790M mutations inEGFR-mutated non-small cell lung cancer (NSCLC) account for nearly 50% of acquired resistance mechanisms to EGFR-TKIs. Earlier studies suggested that tumor T790M could also be detected in TKI-naïve EGFR-mutated NSCLC. The aim of the study is to assess the prevalence and clinical significance of quantification of tumor pre-treatment T790M subclones. We analyzed 366 EGFR-mutated NSCLC patients of the real-life IFCT Biomarkers France study with available pre-treatment formalin-fixed paraffin-embedded (FFPE) tumor DNA before treatment by first/second-generation EGFR-TKI. We used ultra-sensitive Droplet Digital Polymerase Chain Reaction (ddPCR) QX200 (BIO-RAD®, Hercules, CA, USA). All samples were tested in duplicate. ddPCR identified T790M in 19/240 specimens (8%). T790M-positive and T790M-negative populations were not different for clinical baseline characteristics. T790M Variant Allele Frequency (VAF) was > 0.01% <0.1%, > 0.1% <1%, > 1% <10%, and >10% in five (26.3%), six (31.6%), six (31.6%), and two (10.5%) patients, respectively. T790M VAF was >0.1% in 11/13 (84%) patients with rapid (<3 months) or usual progression (3-20 months) compared to 0/3 with low progression (>20 months) (p = 0.02). In a Cox model, T790M mutation positivity was correlated with overall survival (OS) and progression-free survival (PFS) for 10% > VAF >1% (hazard ratio [HR] = 2.83, 95% confidence interval [CI] 1.13-7.07, p = 0.03; HR=3.62, 95%CI 1.43-4.92, p = 0.007, respectively) and for VAF >10% (HR = 19.14, 95%CI 4.35-84.26, p < 0.001; HR = 17.89, 95%CI 2.21-144.86, p = 0.007, respectively). Ultra-sensitive detection of tumor T790M mutation concerned 8% of EGFR-mutated TKI-naïve NSCLC patients and has a negative prognostic value only for T790M VAF over 1%.

Beau-Faller M ，Pencreach E ，Leduc C ，Blons H ，Merlio JP ，Bringuier PP ，de Fraipont F ，Escande F ，Lemoine A ，Ouafik L ，Denis M ，Hofman P ，Lacave R ，Melaabi S ，Langlais A ，Missy P ，Morin F ，Moro-Sibilot D ，Barlesi F ，Cadranel J ，French Cooperative Thoracic Intergroup (IFCT) ... -  《-》

Impact of coexisting gene mutations in EGFR-mutated non-small cell lung cancer before treatment on EGFR T790M mutation status after EGFR-TKIs.

The T790M secondary mutation of epidermal growth factor receptor gene (EGFR) is the most common mechanism of acquired resistance to first- or second-generation EGFR tyrosine kinase inhibitors (TKIs). We investigated the association between gene mutation profile in EGFR mutation-positive non-small cell lung cancer (NSCLC) before EGFR-TKI treatment and T790M status after EGFR-TKI treatment. A total of 57 EGFR mutation-positive NSCLC patients who had undergone a repeat biopsy (tissue or liquid) after failure of treatment with a first- or second-generation EGFR-TKI and who had sufficient tumor tissue available from before treatment for genetic analysis was enrolled. The gene mutation profile of tumor tissue obtained before EGFR-TKI treatment was evaluated by next-generation sequencing with a comprehensive cancer gene panel (409 genes). The number of potentially damaging nonsynonymous mutations was predicted with PolyPhen-2 software. Progression-free survival during EGFR-TKI treatment did not differ significantly between patients who developed T790M-mediated resistance and those who developed T790M-independent resistance. The predicted number of damaging nonsynonymous mutations in pretreatment tumor tissue was significantly lower in patients who developed T790M-mediated resistance than in those with T790M-independent resistance (P =  0.049). Coexisting mutations in tumor tissue before EGFR-TKI treatment may contribute to the emergence of cell clones responsible for development of T790M-dependent or T790M-independent TKI resistance in patients with EGFR-mutated NSCLC. Multiplex genomic testing of pretreatment tumor tissue may thus provide a means of identifying patients likely to develop T790M-mediated TKI resistance and therefore inform treatment selection.

Takeda M ，Sakai K ，Hayashi H ，Tanaka K ，Haratani K ，Takahama T ，Kato R ，Yonesaka K ，Nishio K ，Nakagawa K ... -  《-》

Ultra-sensitive EGFR (T790M) Detection as an Independent Prognostic Marker for Lung Cancer Patients Harboring EGFR (del19) Mutations and Treated with First-generation TKIs.

The detection of preexisting EGFR T790M subclones and the assessment of their clinical significance in the pretreatment of patients with EGFR T790M non-small cell lung cancer (NSCLC) remain unclear. A total of 179 tumor samples from patients treated or not with a first-generation tyrosine kinase inhibitor (TKI) was analyzed. The presence of ultra-low levels of preexisting EGFRT790M mutation was evaluated using ultra-sensitive droplet digital PCR (ddPCR) and the clinical implication of these mutations on first-generation TKI efficiency assessed. With a ddPCR linear performance of 0.999 and an analytical sensitivity of approximately 0.001%, we observed a 66% (99/150) overall incidence of ultra-low EGFR T790M mutation. Among 82 patients harboring EGFR activating mutations, the presence of a preexisting EGFR T790M mutation prior to any treatment was significantly associated with a longer progression-free survival (PFS; P = 0.009; log-rank test). Interestingly, longer PFS was linked to concomitant EGFR del19 and ultra-low EGFR T790M mutations. Moreover, the presence of both EGFR del19 and ultra-low EGFR T790M mutations was identified as the best fit for predicting the clinical outcome of patients treated with TKI compared with an ultra-low EGFR T790M mutation status or an activating mutation alone (P = 0.042 and P = 0.0071, respectively). We demonstrate that the detection of the ultra-low EGFR T790M mutation in TKI-naïve patients is not a rare event. We suggest that ddPCR should be used in clinical practice to distinguish patients who may respond to first- or third-generation TKIs.

Vendrell JA ，Mazieres J ，Senal R ，Rouquette I ，Quantin X ，Pujol JL ，Roch B ，Bouidioua A ，Godreuil S ，Coyaud E ，Brousset P ，Solassol J ... -  《-》

Detection of EGFR-Activating and T790M Mutations Using Liquid Biopsy in Patients With EGFR-Mutated Non-Small-Cell Lung Cancer Whose Disease Has Progressed During Treatment With First- and Second-Generation Tyrosine Kinase Inhibitors: A Multicenter Real-Li

In advanced epidermal growth factor receptor (EGFR)-mutated non-small-cell lung cancer (NSCLC) patients whose disease has progressed during treatment with first- and second-generation tyrosine kinase inhibitors (TKIs), liquid biopsy (LB) is routinely used to evaluate the presence of EGFR T790M as an acquired resistance mechanism. The objective of this study was to assess a real-life picture of EGFR T790M detection in LB. Liquid biopsies performed between June 2016 and October 2018 for advanced EGFR-mutated NSCLC at disease progression during treatment with first- and second-generation TKIs were retrospectively evaluated in 5 Italian centers. Circulating tumor DNA was extracted from plasma and tested with different commercial kits. The detection rate in LBs and the patients' characteristics were correlated. We enrolled 120 consecutive patients. The overall T790M detection rate observed using LB was 25.8%. Fifty-four of 89 (60.7%) patients with negative LB results underwent tissue rebiopsy, and 56% were positive for T790M. The overall rate of T790M positivity in the study cohort was 49.2%. LB performed before formal tumor progression according to Response Evaluation Criteria In Solid Tumors criteria was negative for T790M in all patients (n = 21; P = .012). T790M positivity was statistically significantly higher in cases of disease progression at extrathoracic metastatic sites (P = .008) and, specifically, in the case of worsening bone disease (P = .003). Our study shows that the detection of T790M-positive patients whose disease progressed during treatment with first- and second-generation TKIs in real life was according to the literature. However, this result was obtained with a specific clinical course (repeat LBs and tissue rebiopsy), thus implying the necessity for multidisciplinary management.

Minari R ，Mazzaschi G ，Bordi P ，Gnetti L ，Alberti G ，Altimari A ，Gruppioni E ，Sperandi F ，Parisi C ，Guaitoli G ，Bettelli S ，Longo L ，Bertolini F ，Pagano M ，Bonelli C ，Tagliavini E ，Nicoli D ，Ubiali A ，Zangrandi A ，Trubini S ，Proietto M ，Fiorentino M ，Tiseo M ，DETECTION Study Group ... -  《-》

Predictive impact of low-frequency pretreatment T790M mutation in patients with EGFR-mutated non-small cell lung cancer treated with EGFR tyrosine kinase inhibitors.

Low-frequency epidermal growth factor receptor (EGFR) T790M mutation could be detected by ultrasensitive methods in EGFR tyrosine kinase inhibitor (TKI)-naïve non-small cell lung cancer (NSCLC). However, the impact of pretreatment T790M (preT790M) on the efficacy of EGFR-TKIs and on resistance remains unclear. Two independent cohorts consisting of advanced EGFR-mutated NSCLC patients treated with first-line EGFR-TKIs, a derivation cohort that started treatment between August 2013 and July 2016 (cohort A, n = 44) and a validation cohort between August 2016 and December 2017 (cohort B, n = 22), were examined in this study. Among these, 28 patients underwent re-biopsy at disease progression. DNAs from pretreatment tumor biopsy samples and re-biopsy samples were assessed to detect T790M by the Cobas EGFR Mutation Test v2 (Cobas) and for quantitating T790M by droplet digital polymerase chain reaction (ddPCR). Detection rates of preT790M were 40.9% (18/44) in cohort A and 45.5% (10/22) in cohort B by ddPCR, and none by Cobas. A cutoff value of 0.3% for dividing into high- vs. low-preT790M allele frequency was determined by receiver operating characteristic curve analysis in cohort A. Progression-free survival (PFS) was significantly shorter in the high- preT790M group (n = 12) than in the low-preT790M (n = 6) and negative (n = 26) groups (combined low-preT790M) (median: 6.9 vs. 13.8 months, P =  0.00073). These observations were validated in cohort B [median: 6.2 (n = 5) vs. 15.3 months (n = 17), P =  0.0029]. In 28 paired biopsies, Cobas detected post-progression T790M in 60% (3/5) of the high-preT790M, in 57% (4/7) of the low-preT790M, and in 56% (9/16) of the negative-preT790M groups. EGFR-mutated NSCLC with high preT790M had significantly shorter PFS on EGFR-TKIs. However, preT790M abundance may not necessarily confer post-TKI T790M resistance.

Matsumoto Y ，Sawa K ，Fukui M ，Oyanagi J ，Yoshimoto N ，Suzumura T ，Watanabe T ，Kaneda H ，Mitsuoka S ，Asai K ，Kimura T ，Yamamoto N ，Hirata K ，Koh Y ，Kawaguchi T ... -  《-》