ALK and non-small cell lung carcinoma: Currently limited to its indication in non-small cell lung cancer (NSCLC) that is either ALK positive or ROS positive, crizotinib is actively being researched for its responses in many other types of cancer, such as glioblastoma (although it has a low permeability for the blood-brain barrier, being a P-glycoprotein substrate), gastric and esophageal carcinoma [155], or other GI and haematological malignancies, with regards to its antiangiogenic characteristics [162,163].