Sensitive methods for detection of the S768R substitution in exon 18 of the DDR2 gene in patients with central nervous system metastases of non-small cell lung cancer.

Discoidin death receptor 2 (DDR2) receptor belongs to a DDR family that shows a tyrosine kinase activity. The somatic mutations in DDR2 gene, reported in non-small cell lung cancer (NSCLC), are involved in up-regulation of cells' migration, proliferation and survival. A S768R substitution in DDR2 gene was commonly reported in squamous cell lung carcinoma. Clinical data of patients carrying the DDR2 gene mutation suggest that its presence can be independent of gender and age. The effectiveness of an oral dual-specific (Src and Abl) multikinase inhibitors-dasatinib-was observed in different cell lines and in some NSCLC patients with identified DDR2 mutation. In the present study, we have used three molecular methods (ASP-real-time PCR, ASP-DNA-FLA PCR and direct sequencing) to detect the DDR2 gene mutation in 143 patients with NSCLC metastases to the central nervous system (CNS). The prevalence of the DDR2 gene mutation was correlated with the occurrence of mutations in the EGFR, KRAS, HER2 and BRAF genes. We identified three patients (2.1% of studied group) with DDR2 mutation. The mutation was observed in two patients with low differentiated squamous cell lung cancer and in one patient with adeno-squamous cell carcinoma (ADSCC). In ADSCC patients, DDR2 mutation coexisted with G12C substitution in KRAS gene. According to the current knowledge, examination of the presence of the DDR2 gene mutation in metastatic lesion is the first such report worldwide. The information, that these driver mutations are present in CNS metastases of NSCLC, could broaden therapeutic choices in such group of patients.