LBA85Longitudinal circulating tumour DNA (ctDNA) monitoring for early detection of disease progression and resistance in advanced NSCLC in FLAURA

Abstract Background In the phase III FLAURA study (NCT02296125), the 3rd-generation EGFR-TKI osimertinib showed superior efficacy to comparator EGFR-TKIs in previously untreated EGFR-mutated (EGFRm) advanced non-small cell lung cancer (NSCLC). Here we report results from an exploratory analysis of ctDNA for the early detection of disease progression (PD) in FLAURA. Methods Treatment-naive patients (pts) with EGFRm (ex19del/L858R) locally advanced/metastatic NSCLC (n = 556) were randomised 1:1 (osimertinib 80 mg qd: comparator [gefitinib 250 mg qd/erlotinib 150 mg qd]). Plasma samples were collected on Days 1, 8 and 15, then every 21 days for weeks (W) 3–18, then every 6W thereafter. In pts who had a plasma sample on PD and/or discontinuation, ctDNA droplet digital PCR (ddPCR; Biodesix) for EGFRm (ex19del/L858R/T790M) was performed at all available time points and C797S for post-W6 time points. C797S and T790M were the only resistance mutations assayed. ctDNA progression was defined with respect to the nadir ctDNA result and its proximity to the ddPCR detection and quantification limits. Results The ctDNA progression analysis included 122/556 (22%) pts with valid longitudinal monitoring ddPCR data and RECIST PD by DCO1 (12 June 2017). Across both arms, ctDNA progression preceded or co-occurred with PD in 80/122 (66%) pts with 2.7 months (mo) median lead time; 9.5 mo median progression-free survival (mPFS; n = 80). Acquired C797S or T790M was detected in 57/122 (47%) pts with ctDNA progression (osimertinib 4/50 [8%] C797S, comparator 53/72 [74%] T790M); median time to detection was 16.7 and 8.4 mo for the osimertinib and comparator arms, respectively, mirroring overall mPFS. In pts with ctDNA progression and PD (n = 106), acquired T790M and C797S were detected either at the same time as, or earlier than PD in 41/106 (38%) pts (osimertinib 2/39 [5%], comparator 39/67 [58%]); median lead time was 1.4 mo. Conclusions ctDNA monitoring may allow for earlier identification of pts who progress on first-line EGFR-TKI therapy and the detection of EGFR-mediated resistance mechanisms in advance of PD in EGFRm NSCLC. Future work aims to explore early detection of non-EGFR-mediated resistance. Clinical trial identification NCT02296125. Editorial acknowledgement Donna Tillotson, PhD, of iMed Comms, Macclesfield, UK, an Ashfield Company, part of UDG Healthcare plc, funded by AstraZeneca in accordance with Good Publications Practice (GPP3) guidelines. Legal entity responsible for the study AstraZeneca. Funding AstraZeneca. Disclosure J.E. Gray: Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): AstraZeneca; Research grant / Funding (institution): Array; Research grant / Funding (institution): Merck; Research grant / Funding (institution): Genentech; Research grant / Funding (institution): Boehringer Ingelheim; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Bristol-Myers Squibb; Advisory / Consultancy: Celgene; Honoraria (self), Advisory / Consultancy: Takeda. A. Markovets: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca. N. Nogami: Honoraria (self): Pfizer Inc., Chugai Pharmaceutical Co. Ltd, Eli Lilly, Taiho Pharmaceutical Co. Ltd., AstraZeneca, Kyowa Hakko Kirin, Ono Pharmaceutical Co. Ltd., Bristol-Myers Squibb, MSD. B.C. Cho: Honoraria (institution), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution): Novartis; Honoraria (institution), Advisory / Consultancy, Research grant / Funding (institution): Bayer, AstraZeneca, MOGAM Institute, Dong-A ST, Janssen, Yuhan, Ono Pharmaceutical, Dizal Pharma, MSD; Honoraria (institution), Advisory / Consultancy, Research grant / Funding (institution), Licensing / Royalties: Champions Oncology; Honoraria (institution), Advisory / Consultancy: Boehringer Ingelheim, Roche, Bristol-Myers Squibb, Pfizer, Eli Lilly, Takeda; Shareholder / Stockholder / Stock options: TheraCanVac Inc. B. Chewaskulyong: Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution): AstraZeneca. M. Majem: Advisory / Consultancy, Speaker Bureau / Expert testimony: Roche; Speaker Bureau / Expert testimony, Research grant / Funding (self), Travel / Accommodation / Expenses: Bristol-Myers Squibb; Advisory / Consultancy, Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses: MSD; Advisory / Consultancy, Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses: AstraZeneca; Advisory / Consultancy, Speaker Bureau / Expert testimony: Boehringer Ingelheim; Advisory / Consultancy: Tesaro; Speaker Bureau / Expert testimony: Hellsin; Travel / Accommodation / Expenses: Lilly; Advisory / Consultancy: Takeda; Advisory / Consultancy, Speaker Bureau / Expert testimony: Pierre Fabre; Speaker Bureau / Expert testimony: Amgen. N. Peled: Honoraria (self), Advisory / Consultancy, Research grant / Funding (self): AstraZeneca, Boehringer Ingelheim, Bristol-Myers Squibb, MSD, Novartis, Pfizer, Roche, Takeda; Advisory / Consultancy: Eli Lilly; Honoraria (self): Foundation Medicine; Shareholder / Stockholder / Stock options: Novellus Dx; Honoraria (self): Guardant360. K. Vishwanathan: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca. A. Todd: Full / Part-time employment: AstraZeneca. Y. Rukazenkov: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca. M. Johnson: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca. C. Barrett: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca. J. Chmielecki: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca. R. Hartmaier: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca; Shareholder / Stockholder / Stock options, Licensing / Royalties, Nfe2l2 exon 2 ano/or exon 3 loss from work conducted at Foundation Medicine; provisional patent filed: Foundation Medicine. S.S. Ramalingam: Advisory / Consultancy, Research grant / Funding (self): Amgen, AstraZeneca, Bristol-Myers Squibb, Merck; Advisory / Consultancy: AbbVie, Celgene, Genentech, Lilly, Loxo, Takeda; Research grant / Funding (self): Tesaro.