Detect T790M in cell free tumor DNA of Chinese advanced non-small cell lung cancer adenocarcinoma patients by different platforms and evaluate clinical outcomes of T790M positive patients with osimertinib monotherapy.

Abstract

TPS9104 Background: EGFR T790M mutation occurs in approximately 50-60% of non-small cell lung cancer adenocarcinoma (NSCLC) patients with acquired EGFR-TKI resistance, based on tumor re-biopsies using an invasive clinical procedure. Recently, Cell free tumor DNA (ctDNA) has emerged as a specific and sensitive blood-based biomarker and studies have demonstrated ctDNA as a feasible and minimally invasive alternative to tissue biopsy. Data on different technology platforms used for EGFR T790M detection in blood in China is limited. We aim to compare the methods currently available in hospital practise, including cobas EGFR Mutation Test (Roche Molecular Systems), super-ARMS, digital PCR and NGS, to compare each platform and clinically validate each as companion diagnostic to osimertinib. Methods: This is an open-label, multi-center study in 250 locally advanced or metastatic NSCLC patients with documented EGFR sensitizing mutation and progression on previous EGFR-TKI. T790M mutation in plasma ctDNA will be tested by four methods: cobas, super-ARMS, digital PCR and NGS in order to evaluate the concordance, sensitivity and specificity of T790M testing in plasma between the cobas test and the other platforms. T790M positive patients by any of the four platforms will receive osimertinib treatment (administered orally as one 80 mg tablet once a day in ASTRIS study, NCT02474355) and the clinical outcomes (PFS, ORR, OS) will be followed. Patients will continue to receive osimertinib until disease progression (PD), as assessed by investigators. Digital PCR and NGS will be used to monitor the molecular evolution of T790M and C797S in plasma from NSCLC patients during osimertinib treatment. NGS will also be used to explore acquired resistance mechanisms before osimertinib treatment and after PD. 23 of planned 250 patients have been enrolled in the study as of January 2017. Clinical trial information: NCT02997501.