Clearing of circulating tumour DNA predicts clinical response to osimertinib in EGFR mutated lung cancer patients.

Tyrosine kinase inhibitors (TKIs) are first line treatment choices for patients with epidermal growth factor receptor (EGFR) mutated non-small cell lung cancer (NSCLC). However, responses vary among patients, therefore good biomarkers predicting better responses are required. EGFR mutations are detected in the blood from patients as circulating tumour DNA (ctDNA). Studies have shown that clearing ctDNA during first line TKI treatment predicts outcomes for first and second generation TKI treatments. We aimed to investigate the effects on outcome measures of ctDNA clearing in subsequent treatment lines to treatment with the third generation TKI osimertinib. In total, 225 patients were included in a prospective, multicentre study, where consecutive blood samples were monitored for EGFR mutations during systemic treatment lines, using the Cobas® EGFR mutation test v2. This study focused on EGFR mutations in ctDNA of 82 systemically pre-treated patients receiving osimertinib. Clearing all EGFR mutations from the blood after osimertinib treatment, significantly predicted progression-free survival, objective response rates and disease control rates. Primary sensitising EGFR mutations were found in ctDNA in 70 % of patients, and were accompanied by the T790 M mutation in nearly two thirds of cases. The T790 M mutation was cleared in all cases, while the accompanying sensitising mutations did not necessarily clear. However, T790 M clearing without simultaneously clearing of the primary sensitising mutation did not predict clinical responses. Neither the detection of T790 M before osimertinib treatment, nor the presence of EGFR mutations at the time of osimertinib initiation predicted clinical outcomes. The clearing of EGFR mutations in ctDNA after osimertinib treatment initiation in patients with advanced NSCLC is useful as a positive predictor of clinical outcome.

Boysen Fynboe Ebert E ，McCulloch T ，Holmskov Hansen K ，Linnet H ，Sorensen B ，Meldgaard P ... -  《-》

Predicting osimertinib-treatment outcomes through EGFR mutant-fraction monitoring in the circulating tumor DNA of EGFR T790M-positive patients with non-small cell lung cancer (WJOG8815L).

The WJOG8815L phase II clinical study involves patients with non-small cell lung cancer (NSCLC) that harbored the EGFR T790M mutation, which confers resistance to EGFR tyrosine kinase inhibitors (TKIs). The purpose of this study was to assess the predictive value of monitoring EGFR genomic alterations in circulating tumor DNA (ctDNA) from patients with NSCLC that undergo treatment with the third-generation EGFR-TKI osimertinib. Plasma samples of 52 patients harboring the EGFR T790M mutation were obtained pretreatment (Pre), on day 1 of treatment cycle 4 (C4) or cycle 9 (C9), and at diagnosis of disease progression or treatment discontinuation (PD/stop). CtDNA was screened for EGFR-TKI-sensitizing mutations, the EGFR T790M mutation, and other genomic alterations using the cobas EGFR Mutation Test v2 (cobas), droplet digital PCR (ddPCR), and targeted deep sequencing. Analysis of the sensitizing-and T790M-EGFR mutant fractions (MFs) was used to determine tumor mutational burden. Both MFs were found to decrease during treatment, whereas rebound of the sensitizing EGFR MF was observed at PD/stop, suggesting that osimertinib targeted both T790M mutation-positive tumors and tumors with sensitizing EGFR mutations. Significant differences in the response rates and progression-free survival were observed between the sensitizing EGFR MF-high and sensitizing EGFR MF-low groups (cutoff: median) at C4. In conclusion, ctDNA monitoring for sensitizing EGFR mutations at C4 is suitable for predicting the treatment outcomes in NSCLC patients receiving osimertinib (Clinical Trial Registration No.: UMIN000022076).

Sakai K ，Takahama T ，Shimokawa M ，Azuma K ，Takeda M ，Kato T ，Daga H ，Okamoto I ，Akamatsu H ，Teraoka S ，Ono A ，Ohira T ，Yokoyama T ，Yamamoto N ，Nakagawa K ，Nishio K ... -  《-》

Clearing of circulating tumour DNA predicts clinical response to first line tyrosine kinase inhibitors in advanced epidermal growth factor receptor mutated non-small cell lung cancer.

Epidermal growth factor receptor (EGFR) mutations confer sensitivity to tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC). However, a subset of patients has limited or no response. We investigated the initial dynamics of EGFR mutations detected in circulating tumour DNA (ctDNA) during treatment as a predictive marker of outcome. A total of 225 patients with advanced EGFR mutated NSCLC were included for consecutive blood sampling in this prospective multicentre study. Out of these, 146 patients received first line TKI and had a baseline blood sample available for EGFR mutation testing with the Cobas® EGFR mutation test V2. For examinations on clearing and clinical outcome, 98 patients who had detectable ctDNA at baseline and at least one follow-up blood sample were included. For patients with EGFR mutations present in plasma at baseline, clearing of mutations from the blood during first line TKI served as a positive predictor for objective response rate (p = 0.0008), progression-free survival (PFS) (p < 0.0001) and overall survival (OS) (p < 0.0001). This was seen both for patients who cleared the ctDNA within the first 7 weeks of treatment and patients who cleared the ctDNA at a slower pace. Baseline mutation presence was a negative predictor for PFS (p = 0.0069) and OS (p = 0.0340). The current study is the first to confirm, in a sizeable Caucasian cohort, that clearing of EGFR mutations predict outcome to first line TKI in patients with EGFR mutated NSCLC.

Ebert EBF ，McCulloch T ，Hansen KH ，Linnet H ，Sorensen B ，Meldgaard P ... -  《-》

Osimertinib in T790M-positive and -negative patients with EGFR-mutated advanced non-small cell lung cancer (the TREM-study).

In non-small cell lung cancer patients with acquired resistance to first- or second-generation EGFR-TKIs, osimertinib is approved in the presence of the T790 M resistance mutation. We assessed the efficacy of osimertinib in both T790M-positive and T790M-negative patients. The TREM-study is an investigator-initiated, multi-centre, single-arm, phase 2 clinical trial conducted in five Northern European countries. Patients with progression on at least one previous EGFR-TKI were assigned to treatment with 80 mg of osimertinib daily until radiological progression or death. Patients were included regardless of the presence of T790 M. The primary endpoint was objective response rate (ORR). Of 199 included patients, 120 (60 %) were T790M-positive, 52 (26 %) were T790M-negative and 27 (14 %) had unknown T790M-status. 24 % had brain metastases and 15 % had an ECOG performance status of 2. Overall ORR was 48 % (95 % CI, 41 %-55 %), 60 % (51 %-69 %) for T790M-positive patients and 28 % (15 %-41 %) for T790M-negative patients, p < 0.001. ORR for patients with co-occurring del19 vs L858R was 61 % vs 32 %, p = 0.001. Duration of response was similar between the T790M-positive and -negative groups (11.8 vs 10.7 months, p = 0.229). Overall median progression-free survival (PFS) was 8.9 months (95 % CI, 7.4-10.5), and 10.8 vs 5.1 months for T790M-positive vs -negative patients (HR 0.62, p = 0.007). Median overall survival (OS) was 17.9 months (95 % CI, 14.4-21.3). For T790M-positive vs -negative median OS was 22.5 vs 13.4 months, (HR 0.55, p = 0.002). This study confirms the efficacy of osimertinib for T790M-positive patients. There was also clinically significant activity of osimertinib in a proportion of T790M-negative patients. This trial is registered with ClinicalTrials.gov (NCT02504346).

Eide IJZ ，Helland Å ，Ekman S ，Mellemgaard A ，Hansen KH ，Cicenas S ，Koivunen J ，Grønberg BH ，Brustugun OT ... -  《-》

EGFR T790M detection and osimertinib treatment response evaluation by liquid biopsy in lung adenocarcinoma patients with acquired resistance to first generation EGFR tyrosine kinase inhibitors.

Li C ，Jia R ，Liu H ，Zhang B ，Wang C ... -  《Diagnostic Pathology》