ROS1-positive lung cancer occurs when a gene called ROS1 fuses with a nearby gene. This fusion causes the ROS1 gene to remain stuck in the “on” position. This “drives” abnormal cell growth, which is what cancer is. The ROS1 gene is a receptor tyrosine kinase, a cell surface receptor that has been shown not only to be a key regulator of normal cellular processes, but it also has a critical role in the development and progression of many types of cancer, including lung cancer.
ROS1 is an oncogene, like the ALK oncogene, and, in fact, is related to ALK. According to the National Cancer Institute, an oncogene is a gene that is, under normal circumstances, involved in cell growth, but becomes cancerous if a mutation occurs. Patients with a ROS1 rearrangement respond well to some of the same treatments that are used to treat ALK-positive lung cancer patients.
Dr. David Carbone, of the James Cancer Center at Ohio State University, says, “Immunotherapy has revolutionized lung cancer treatments for many patients.”
However, patients with a ROS1 biomarker driving their cancer are less likely to benefit from immunotherapy than other lung cancer patients. Dr. Carbone recommends starting with ROS1 targeted therapies first. The idea is to continue those as long as they’re working.