DDR2 and non-small cell lung carcinoma: FGFR fusions, phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PI3KCA) mutations, and discoidin domain receptor tyrosine kinase 2 (DDR2) mutations are additional rare genetic alterations associated with NSCLC requiring further investigation in terms of their relationship with CNS metastases [111].