Detection of EGFR, KRAS and BRAF mutations in metastatic cells from cerebrospinal fluid

• Published in: Clinical chemistry and laboratory medicine Vol. 56; no. 5; p. 851
• Main Authors: Frankel, Diane, Nanni-Metellus, Isabelle, Robaglia-Schlupp, Andrée, Tomasini, Pascale, Guinde, Julien, Barlesi, Fabrice, Astoul, Philippe, Ouafik, L'Houcine, Amatore, Florent, Secq, Véronique, Kaspi, Elise, Roll, Patrice
• Format: Journal Article
• Language: English
• Published: Germany 25-04-2018
• Subjects: Adenocarcinoma of Lung - cerebrospinal fluid; Adenocarcinoma of Lung - genetics; Adenocarcinoma of Lung - pathology; Aged; ErbB Receptors - chemistry; ErbB Receptors - genetics; Female; Humans; Lung Neoplasms - cerebrospinal fluid; Lung Neoplasms - genetics; Lung Neoplasms - pathology; Male; Middle Aged; Mutation; Proto-Oncogene Proteins B-raf - chemistry; Proto-Oncogene Proteins B-raf - genetics; Proto-Oncogene Proteins p21(ras) - chemistry; Proto-Oncogene Proteins p21(ras) - genetics; meningeal metastasis; BRAF; KRAS; EGFR; cerebrospinal fluid; lung adenocarcinoma
• ISSN: 1437-4331
• DOI: 10.1515/cclm-2017-0527

In lung adenocarcinoma, molecular profiling of actionable genes has become essential to set up targeted therapies. However, the feasibility and the relevance of molecular profiling from the cerebrospinal fluid (CSF) in the context of meningeal metastasis have been poorly assessed.
We selected patients with stage IV lung adenocarcinoma harbouring metastatic cells in the CSF after cytological analysis. Seven samples from six patients were eligible for molecular testing of epidermal growth factor receptor (EGFR), V-Ki-ras2 Kirsten rat sarcoma viral oncogene homologue (KRAS), v-Raf murine sarcoma viral oncogene homologue B1 (BRAF) and human epidermal growth factor receptor 2 (HER2) mutations using quantitative polymerase chain reaction (PCR) high-resolution melting curve analysis and Sanger sequencing after DNA extraction from the cell pellets of the CSF.
Five patients showed mutations in one or two actionable genes, two harboured an EGFR mutation (exons 19 and 21), one only a KRAS mutation, one both EGFR and KRAS mutations and one a BRAF mutation. In all cases, the results of mutation testing provided new major information for patient management, leading to therapeutic adaptation. CSF molecular analysis identified mutations not detected in other neoplastic sites for two patients. In one case, the EGFR p.Thr790Met was identified. CSF was also the only sample available for genetic testing for almost all patients at the time of disease progression.
When cancer cells are present in the CSF, the molecular profiling from the cell pellets is relevant, as it can detect supplemental or different mutations compared to a previous analysis of the primitive tumour or plasma cell-free DNA and allows the adaptation of the treatment strategy.