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
3611 - Phase II trial of SM 88 in Non-Metastatic Biochemical Recurrent Prostate Cancer.
Presenter: Benjamin Gartrell
Session: Poster Display session 3
Resources:
Abstract
2492 - A phase 1 study of Ad5 PSA/MUC-1/Brachyury Vaccine in Patients with Metastatic Castration Resistant Prostate Cancer (mCRPC)
Presenter: Marijo Bilusic
Session: Poster Display session 3
Resources:
Abstract
3142 - Multicenter Phase I Trial of a DNA Vaccine Encoding the Androgen Receptor Ligand Binding Domain (pTVG-AR, MVI-118) in Patients with Metastatic Prostate Cancer
Presenter: Douglas McNeel
Session: Poster Display session 3
Resources:
Abstract
4327 - Impact of germline mutations in Homologous Recombination (HR) genes on the response to Radium-223 for metastatic castration resistant prostate cancer (mCRPC)
Presenter: Elena Castro
Session: Poster Display session 3
Resources:
Abstract
3600 - Serum biomarkers of bone metabolism in metastatic castration-resistant prostate cancer (mCRPC) patients (pts) treated with Radium-223 (Ra223): Results from a prospective multicentre study
Presenter: Nuria Romero Laorden
Session: Poster Display session 3
Resources:
Abstract
3742 - Prognostic value of tumor suppression genes (TP53, PTEN, Rb) in metastatic hormone sensitive prostate cancer
Presenter: Miguel Gonzalez Velez
Session: Poster Display session 3
Resources:
Abstract
2643 - Germline sequencing of advanced prostate cancer patients in the BARCODE2 trial
Presenter: Sarah Benafif
Session: Poster Display session 3
Resources:
Abstract
4349 - Impact of treatment sequence in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC): data from the prospective PROREPAIR-B study.
Presenter: Carlo Cattrini
Session: Poster Display session 3
Resources:
Abstract
3301 - Implications of Single Nucleotide Polymorphisms (SNPs) in Androgen Related-Genes in Outcome of metastatic castration-resistant prostate cancer (mCRPC) patients treated with Abiraterone (Abi) and Enzalutamide (Enza)
Presenter: Isabel Aragon
Session: Poster Display session 3
Resources:
Abstract
2275 - Activating mutations in AKT1/PIK3CA are associated with poor clinical outcomes in metastatic prostate cancer (mPC)
Presenter: Simon Fu
Session: Poster Display session 3
Resources:
Abstract