Abstract 5664
Background
Liquid biopsy is a minimally invasive strategy to detect genetic alterations in non-small cell lung cancer (NSCLC) patients. In particular, it is clinically useful for the detection of the EGFR T790M resistance mutation in advanced EGFR-mutated NSCLC patients who had progressed under treatment with an EGFR-TKI. While plasma analysis is commonly performed, sputum could be another potential source for circulating tumor DNA (ctDNA) in NSCLC, which has not yet been entirely evaluated.
Methods
Paired plasma and sputum samples from 23 patients with EGFR-mutated lung adenocarcinoma were analyzed for EGFR exon 19 deletions (del19), L858R, and T790M mutations by droplet digital PCR (ddPCR). All patients had histologically confirmed lung adenocarcinoma with EGFR mutations in their initial tissue biopsy at diagnosis.
Results
Tissue genotyping at diagnosis revealed 18 patients with EGFR del19 and 5 patients with L858R mutations. Among the 18 EGFR del19-positive patients, 8 showed concordant test results in plasma and sputum (2 positive, 6 negative), 6 had del19-positive plasma samples but del19-negative sputum samples, 4 were del19 negative in plasma and del19 positive in sputum. Among 5 L8585R-positive patients, 4 had concordant test results in plasma and sputum (3 positive, 1 negative), one patient was L858R positive in the plasma sample but L858R negative in sputum. In 10 out of 23 patients the T790M mutation was assessed in paired samples, 9 showed concordant test results in plasma and sputum (3 positive, 6 negative), one patient was T790M positive only in the sputum sample.
Conclusions
Our results show a high concordance between plasma and sputum for EGFR L858R and T790M mutation testing. A lower concordance was observed for EGFR del19. Thus liquid biopsy from sputum is a promising strategy that should be further evaluated.
Clinical trial identification
GS1-EK4/479-2017, 20.07.2017 EK-18-172-0918, 08.11.2018.
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
3489 - Overall Survival (OS) and Metastasis-Free Survival (MFS) in men with Biochemically Relapsed (BCR) Prostate Cancer after radical prostatectomy (RP) managed with deferred Androgen Deprivation Treatment (ADT): A combined Johns Hopkins and CPDR study
Presenter: Catherine Marshall
Session: Poster Display session 3
Resources:
Abstract
4606 - ARCHES – the role of androgen deprivation therapy (ADT) with enzalutamide (ENZA) or placebo (PBO) in metastatic hormone-sensitive prostate cancer (mHSPC): Post hoc analyses of high and low disease volume and risk groups
Presenter: Arnulf Stenzl
Session: Poster Display session 3
Resources:
Abstract
2975 - Updated survival analyses of a multicentric phase II randomized trial of docetaxel (D) plus enzalutamide (E) versus docetaxel (D) as first line chemotherapy for patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) (CHEIRON study).
Presenter: Orazio Caffo
Session: Poster Display session 3
Resources:
Abstract
2708 - Real-world analysis of patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) receiving vs not receiving chemotherapy in the treatment sequence
Presenter: Alicia Morgans
Session: Poster Display session 3
Resources:
Abstract
2134 - Baseline fracture risk in men with prostate cancer starting the STAMPEDE trial
Presenter: Janet Brown
Session: Poster Display session 3
Resources:
Abstract
3504 - Risk of falls and fractures in patients with castration resistant prostate cancer (CRPC) treated with new hormonal agents – a meta-analysis of randomized controlled trials.
Presenter: Rodrigo Coutinho Mariano
Session: Poster Display session 3
Resources:
Abstract
2342 - Pain progression at initiation of chemotherapy in metastatic Castration-Resistant Prostate Cancer (mCRPC) is associated with a poor prognosis: a post-hoc analysis of FIRSTANA
Presenter: Nicolas Delanoy
Session: Poster Display session 3
Resources:
Abstract
5331 - Pain evaluation in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) treated with radium-223 (Ra-223) in the PARABO observation study
Presenter: Holger Palmedo
Session: Poster Display session 3
Resources:
Abstract
2823 - Time to castration resistant prostate cancer (CRPC) and the risk of developing immune disorders
Presenter: Vincenza Conteduca
Session: Poster Display session 3
Resources:
Abstract
1500 - Retrospective evaluation of neutropenic admission events in metastatic or high-risk hormone-sensitive prostate cancer (HSPC) patients having docetaxel chemotherapy upfront or for castrate-resistant prostate cancer (CRPC) in STAMPEDE
Presenter: Harriet Mintz
Session: Poster Display session 3
Resources:
Abstract