Lorlatinib is an investigational medicine that inhibits the anaplastic lymphoma kinase (ALK) and ROS1 proto-oncogene. Lorlatinib was specifically designed to inhibit tumor mutations that drive resistance to other ALK inhibitors. Lorlatinib has in vitro activity against ALK and number of other tyrosine kinase receptor related targets including ROS1, TYK1, FER, FPS, TRKA, TRKB, TRKC, FAK, FAK2, and ACK. Lorlatinib demonstrated in vitro activity against multiple mutant forms of the ALK enzyme, including some mutations detected in tumors at the time of disease progression on crizotinib and other ALK inhibitors. Moreover, lorlatinib possesses the capability to cross the blood-brain barrier, allowing it to reach and treat progressive or worsening brain metastases as well. Lorlatinib is a third-generation anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor (TKI) indicated for the treatment of patients with ALK-positive metastatic non-small cell lung cancer (NSCLC) whose disease has progressed on a) the prior use of crizotinib and at least one other ALK inhibitor for metastatic disease, or b) the prior use of alectinib as the first ALK inhibitor therapy for metastatic disease, or c) the prior use of certinib as the first ALK inhibitor therapy for metastatic disease.