Crizotinib

Crizotinib is a tyrosine kinase receptor inhibitor that targets anaplastic lymphoma kinase (ALK), hepatocyte growth factor receptor (HGFR, c-MET), ROS1 (c-ros), and Recepteur d'Origine Nantais (RON). When activated, ALK inhibits apoptosis and promotes cell proliferation, and ALK-gene translocations can lead to the expression of oncogenic fusion proteins. A small portion of non-small cell lung cancer (NSCLC) patients have ALK-positive tumors. Most of these cases are characterized by the fusion of ALK with the chimeric protein echinoderm microtubule-associated protein-like 4 (EML4), resulting in increased kinase activity. Crizotinib inhibits ALK by inhibiting its phosphorylation and creating an inactive protein conformation. This ultimately lowers the proliferation of cells carrying this genetic mutation and tumour survivability.

In vitro assays on tumor cell lines demonstrated that crizotinib inhibits ALK, ROS1, and c-Met phosphorylation in a concentration-dependent manner. In vivo studies in mice with tumor xenografts that expressed EML4- or nucleophosmin (NPM)-ALK fusion proteins or c-Met showed that crizotinib has antitumor activity.