An orally available inhibitor of the receptor tyrosine kinase anaplastic lymphoma kinase (ALK) with antineoplastic activity. Upon administration, alectinib binds to and inhibits ALK kinase, ALK fusion proteins as well as the gatekeeper mutation ALKL1196M known as one of the mechanisms of acquired resistance to small-molecule kinase inhibitors. The inhibition leads to disruption of ALK-mediated signaling and eventually inhibits tumor cell growth in ALK-overexpressing tumor cells. ALK belongs to the insulin receptor superfamily and plays an important role in nervous system development. ALK dysregulation and gene rearrangements are associated with a series of tumors. OR A drug used to treat non-small cell lung cancer that has spread to other parts of the body and has a mutated (changed) form of a gene called anaplastic lymphoma kinase (ALK). It is used in patients whose cancer has gotten worse after treatment with or who cannot receive crizotinib (a type of anticancer drug). Alectinib blocks the protein made by the mutated ALK gene. Blocking this protein may stop the growth and spread of cancer cells. Alectinib is a type of tyrosine kinase inhibitor. Also called Alecensa.