Approximately 3 to 5% of non-small cell lung carcinomas (NSCLC) have a rearrangement of the ALK (Anaplastic Lymphoma Kinase) gene, resulting in fusion between ALK and another gene, ALK activation, impaired apoptosis, and abnormal cell proliferation. Tumors expressing ALK fusions are likely to respond to ALK kinase inhibitor drugs such as XALKORI® (crizotinib).
The National Comprehensive Cancer Network (NCCN) guidelines recommend ALK testing for patients with recurrent or metastatic NSCLC with histological subtypes of adenocarcinoma, large cell carcinoma, or NSCLC NOS (not otherwise specified), and for squamous cell carcinoma in never-smokers or when biopsy specimens are small.
FISH is preferred over molecular testing for ALK testing because it detects all known gene rearrangements. The ALK gene has more than 20 known rearrangement partner genes. The most common EML4-ALK fusion has at least 15 variants. Vysis ALK Break Apart FISH Probe Kit is an FDA approved companion diagnostic tests to identify patients for this therapy
In addition to the proven role it plays in select lung cancers, ALK has been found to have a pathogenic role in many cancers including diffuse large B-cell lymphoma, inflammatory myofibroblastic tumor, esophageal squamous cell carcinoma, colorectal cancer and breast cancer. It is estimated that more than 250,000 new cancer diagnoses in the United States each year can be linked to ALK mutations and fusions.