RESUMO
Liquid biopsy has improved significantly over the last decade and is attracting attention as a tool that can complement tissue biopsy to evaluate the genetic landscape of solid tumors. In the present study, we evaluated the usefulness of liquid biopsy in daily oncology practice in different clinical contexts. We studied ctDNA and tissue biopsy to investigate EGFR, KRAS, NRAS, and BRAF mutations from 199 cancer patients between January 2016 and March 2021. The study included 114 male and 85 female patients with a median age of 68 years. A total of 122 cases were lung carcinoma, 53 were colorectal carcinoma, and 24 were melanoma. Liquid biopsy was positive for a potentially druggable driver mutation in 14 lung and colorectal carcinoma where tissue biopsy was not performed, and in two (3%) lung carcinoma patients whose tissue biopsy was negative. Liquid biopsy identified nine (45%) de novo EGFR-T790M mutations during TKI-treatment follow-up in lung carcinoma. BRAF-V600 mutation resurgence was detected in three (12.5%) melanoma patients during follow-up. Our results confirm the value of liquid biopsy in routine clinical oncologic practice for targeted therapy, diagnosis of resistance to treatment, and cancer follow-up.
RESUMO
BACKGROUND: SARS-CoV-2 is a positive-sense single-stranded RNA virus. It is enveloped by four structural proteins. The entry of the virus into the host cells is mediated by spike protein binding to the angiotensin converting enzyme 2 (ACE2) and proteolytic cleavage by transmembrane protease serine 2 (TMPRSS2). In this study, we analyzed the expression of the ACE2 receptor and TMPRSS2 in cases under investigation for SARS-CoV-2 infection. METHODS: The study was carried out using the viral transport medium of consecutive nasopharyngeal swabs from 300 people under examination for SARS-CoV-2 infection. All samples underwent the SARS-CoV-2 transcriptase-mediated amplification assay (Procleix® SARS-CoV-2) to detect the virus. Immunocytochemistry was used in each sample to detect the presence of the SARS-CoV-2 nucleoprotein, the ACE2 receptor, and TMPRSS2. RESULTS: An immunocytochemical study with monoclonal antibody against SARS-CoV-2 viral nucleoprotein showed positivity in squamous cells. ACE2 were not detected in the squamous cells obtained from the nasopharyngeal samples. CONCLUSIONS: SARS-CoV-2 predominantly localizes to squamous cells in cytology samples of patients with positive transcriptase-mediated amplification SARS-CoV-2 assay results. The immunocytochemical negativity for ACE2 evidenced in the present study could be related to the cellular heterogeneity present in the nasopharyngeal smear samples and could be related to variations at the genomic level. Our results suggest that SARS-CoV-2 might be present in the nasopharyngeal region because viral cell junctions are weaker. This facilitates viral concentration, infective capacity and migration to specific organs, where SARS-CoV-2 infects target cells by binding to their receptors and then entering.