ALK and cancer: Hence, crizotinib (Xalkori®), an anti-cancer drug that inhibits ROS1 (c-ros oncogene 1) and ALK, is used for the 5% of patients that will respond to this drug because they have a chromosomal rearrangement that produces a gene fusion (ALK and EML4, echinoderm microtubule-associated protein-like 4) that results in carcinogenesis.