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2019 ASCO Annual Meeting!

Session: Lung Cancer—Non-Small Cell Metastatic

Type: Poster Session

Time: Sunday June 2, 8:00 AM to 11:00 AM

Location: Hall A

Quantification of circulating free and circulating tumor DNA in pretreated EGFR mutant NSCLC to inform patient outcomes.

Metastatic Non-Small Cell Lung Cancer

Lung Cancer—Non-Small Cell Metastatic

2019 ASCO Annual Meeting

Abstract No:

Poster Board Number:
Poster Session (Board #403)

J Clin Oncol 37, 2019 (suppl; abstr 9080)

Author(s): Alexandra Pender, Curtis Hughesman, Elaine Law, Amadea Kristanti, Kelly McNeil, Tracy Tucker, Ian Bosdet, Sean Young, Janessa J. Laskin, Aly Karsan, Stephen Yip, Cheryl Ho; British Columbia Cancer Agency, Vancouver, BC, Canada; Department of Pathology, BC Cancer Agency and University of British Columbia, Vancouver, BC, Canada; BC Cancer, Vancouver, BC, Canada; BC Cancer Agency, Vancouver, BC, Canada

Abstract Disclosures


Background: EGFR T790M testing is standard of care for EGFR mutant (EGFRm) NSCLC progressing on 1st/2nd generation TKIs to select patients for osimertinib. Circulating free DNA (cfDNA) levels are measured prior to circulating tumour DNA (ctDNA) testing using droplet digital PCR (ddPCR) to measure activating/resistant EGFR mutations. We reviewed cfDNA levels and ctDNA mutational status to determine the influence on patient outcome. Methods: Following extraction of cfDNA from plasma using the QIAamp Circulating Nucleic Acid Kit, cfDNA levels are measured with a Qubit 2.0 Fluorometer. Custom ddPCR assays were used to test for the appropriate EGFR activating mutation and the EGFR T790M resistance mutation using the Bio-Rad QX200 system. The custom designed ddPCR assays have a limit of detection of < 0.1% variant allele fraction. All patients undergoing ctDNA testing from February-December 2018 were identified. Baseline characteristics and follow up data were collected retrospectively. OS was calculated from date of metastatic diagnosis to death/last follow-up. Results: 142 patients with EGFR mutant adenocarcinoma had EGFR ctDNA testing: results 52% indeterminant, 32% T790M, 16% activating EGFRm only. At the time of testing: median age 66, 64% female, 57% never smokers 53% Asian; systemic treatment (tx) 62% first line only, 25% two lines and 13% ≥ three lines. First TKI therapy: 32% afatanib, 66% gefitinib, 2% erlotinib. Median cfDNA concentration was 5.65 ng/ml (range 0.50-217.72). The 5 yr OS was 72% below cfDNA median and 25% above the median. Tx after ctDNA testing for below and above cfDNA median: 52 vs 33% original TKI, 34 vs 55% osimertinib, 14 vs 12% other systemic tx. Multivariate analysis shows that even accounting for age, sex and ctDNA mutation result, cfDNA concentration remains an independent predictor of outcome (HR 2.36, 95% CI 1.08-5.18, p = 0.032). Conclusions: cfDNA concentration can predict patient outcome in patients with EGFR mutant NSCLC progressing on TKI regardless of ctDNA testing results. Clinicians may consider switching to chemotherapy for patients with high cfDNA and without detectable EGFRT790M ctDNA to avoid missing the window for therapy instead of awaiting repeat EGFR T790M testing

Other Abstracts in this Sub-Category:


1. Association of STK11/LKB1 genomic alterations with lack of benefit from the addition of pembrolizumab to platinum doublet chemotherapy in non-squamous non-small cell lung cancer.

Meeting: 2019 ASCO Annual Meeting Abstract No: 102 First Author: Ferdinandos Skoulidis
Category: Lung Cancer—Non-Small Cell Metastatic - Metastatic Non-Small Cell Lung Cancer


2. Real-world outcomes of patients with advanced non-small cell lung cancer (aNSCLC) and autoimmune disease (AD) receiving immune checkpoint inhibitors (ICIs).

Meeting: 2019 ASCO Annual Meeting Abstract No: 110 First Author: Sean Khozin
Category: Lung Cancer—Non-Small Cell Metastatic - Metastatic Non-Small Cell Lung Cancer


3. RELAY: A multinational, double-blind, randomized Phase 3 study of erlotinib (ERL) in combination with ramucirumab (RAM) or placebo (PL) in previously untreated patients with epidermal growth factor receptor mutation-positive (EGFRm) metastatic non-small cell lung cancer (NSCLC).

Meeting: 2019 ASCO Annual Meeting Abstract No: 9000 First Author: Kazuhiko Nakagawa
Category: Lung Cancer—Non-Small Cell Metastatic - Metastatic Non-Small Cell Lung Cancer