LDK378, also known as ceritinib, is primarily used in the treatment of non-small cell lung cancer (NSCLC) that is anaplastic lymphoma kinase (ALK)-positive. It is specifically designed to target and inhibit the ALK protein, which is involved in the growth and spread of cancer cells. This medication is particularly effective in patients who have developed resistance to other ALK inhibitors, such as crizotinib. By blocking the ALK protein, LDK378 helps to slow down or stop the progression of the cancer, improving patient outcomes. It is typically administered orally and is often used when the cancer has metastasized or cannot be treated with surgery. Regular monitoring and management of side effects are essential during treatment with LDK378.