Ensartinib is primarily used in the treatment of non-small cell lung cancer (NSCLC), particularly for patients whose tumors have specific genetic mutations, such as ALK (anaplastic lymphoma kinase) rearrangements. It functions as an ALK inhibitor, targeting and blocking the activity of the ALK protein, which is involved in the growth and spread of cancer cells. By inhibiting this protein, ensartinib helps to slow down or stop the progression of the disease. It is often prescribed for patients who have developed resistance to other ALK inhibitors or as a first-line treatment option. The drug is administered orally, making it convenient for patients to use on a regular basis. Clinical trials have shown that ensartinib can be effective in shrinking tumors and improving progression-free survival in patients with ALK-positive NSCLC.