Autor(es):
Silveira, Catarina ; Sousa, Ana Carla ; Janeiro, André ; Malveiro, Sara ; Teixeira, Encarnação ; Brysch, Eva ; Pantarotto, Marcos ; Felizardo, Margarida ; Madureira, Rosa ; Nogueira, Fernando ; Guimarães, Cátia ; Matos, Cristina ; Canário, Dolores ; Bruges-Armas, Jácome ; Carmo-Fonseca, Maria
Data: 2021
Identificador Persistente: http://hdl.handle.net/10451/47623
Origem: Repositório da Universidade de Lisboa
Assunto(s): EGFR T790M mutation; Lung cancer; Droplet digital PCR (ddPCR); Liquid biopsy
Descrição
Background: Liquid biopsy allows the identification of targetable cancer mutations in a minimally invasive manner. In patients with advanced non-small cell lung cancer (NSCLC), droplet digital PCR (ddPCR) is increasingly used to genotype the epidermal growth factor receptor (EGFR) gene in circulating cell-free DNA (cfDNA). However, the sensitivity of this method is still under debate. The aim of this study was to implement and assess the performance of a ddPCR assay for detecting the EGFR T790M mutation in liquid biopsies. Methods: A ddPCR assay was optimized to detect the EGFR T790M mutation in plasma samples from 77 patients with NSCLC in progression. Results: Our ddPCR assay enabled the detection and quantification of the EGFR T790M mutation at cfDNA allele frequency as low as 0.5%. The mutation was detected in 40 plasma samples, corresponding to a positivity rate of 52%. The number of mutant molecules per mL of plasma ranged from 1 to 6,000. A re-biopsy was analyzed for 12 patients that had a negative plasma test and the mutation was detected in 2 cases. A second liquid biopsy was performed for 6 patients and the mutation was detected in 3 cases. Conclusions: This study highlights the value of ddPCR to detect and quantify the EGFR T790M mutation in liquid biopsies in a real-world clinical setting. Our results suggest that repeated ddPCR tests in cfDNA may obviate tissue re-biopsy in patients unable to provide a tumor tissue sample suitable for molecular analysis.
