Crizotinib, sold under the brand name Xalkori among others, is an anti-cancer medication used for the treatment of non-small cell lung carcinoma (NSCLC). It acts as an ALK (anaplastic lymphoma kinase) and ROS1 (c-ros oncogene 1) inhibitor. Medical uses Crizotinib is indicated for the treatment of metastatic non-small cell lung cancer (NSCLC) or relapsed or refractory, systemic anaplastic large cell lymphoma (ALCL) that is ALK-positive. It is also indicated for the treatment of unresectable, recurrent, or refractory inflammatory anaplastic lymphoma kinase (ALK)-positive myofibroblastic tumors (IMT). Mechanism of action Crizotinib has an aminopyridine structure, and functions as a protein kinase inhibitor by competitive binding within the ATP-binding pocket of target kinases. About 4% of patients with non-small cell lung carcinoma have a chromosomal rearrangement that generates a fusion gene between EML4 ('echinoderm microtubule-associated protein-like 4') and ALK ('anaplastic lymphoma kinase'), which results in constitutive kinase activity that contributes to carcinogenesis and seems to drive the malignant phenotype. The kinase activity of the fusion protein is inhibited by crizotinib. Patients with this gene fusion are typically younger non-smokers who do not have mutations in either the epidermal growth factor receptor gene (EGFR) or in the K-Ras gene. The number of new cases of ALK-fusion NSLC is about 9,000 per year in the U.S. and about 45,000 worldwide. ALK mutations are thought to be important in driving the malignant phenotype in about 15% of cases of neuroblastoma, a rare form of peripheral nervous system cancer that occurs almost exclusively in very young children. Crizotinib inhibits the c-Met/Hepatocyte growth factor receptor (HGFR) tyrosine kinase, which is involved in the oncogenesis of a number of other histological forms of malignant neoplasms. Crizotinib is thought to exert its effects through modulation of the growth, migration, and invasion of malignant cells. Other studies suggest that crizotinib might also act via inhibition of angiogenesis in malignant tumors. Society and culture Legal status On August 24, 2011, the U.S. Food and Drug Administration approved crizotinib to treat certain late-stage (locally advanced or metastatic) non-small cell lung cancers that express the abnormal anaplastic lymphoma kinase (ALK) gene. Approval required a companion molecular test for the EML4-ALK fusion. In March 2016, the U.S. Food and Drug Administration approved crizotinib in ROS1-positive non-small cell lung cancer. In October 2012, the European Medicines Agency (EMA) approved the use of crizotinib to treat non-small cell lung cancers that express the abnormal anaplastic lymphoma kinase