What condition is Lapatinib primarily used to treat?

Lapatinib is primarily used to treat breast cancer, specifically in cases that are human epidermal growth factor receptor 2 (HER2) positive. This targeted therapy works by inhibiting the activity of the HER2 protein, which is overexpressed in some breast cancers, leading to more aggressive disease and poorer prognosis. By blocking this receptor, Lapatinib can help slow down or stop the growth of cancer cells that are dependent on HER2 for proliferation.

In contrast, the other conditions listed are primarily treated with different therapies. Non-small cell lung cancer typically relies on chemotherapy, targeted therapies, or immunotherapy tailored to specific mutations. Acute lymphoblastic leukemia usually involves intensive chemotherapy and possibly stem cell transplantation. Pancreatic cancer treatment often focuses on surgical options, chemotherapy, and radiation, depending on the stage at diagnosis. Hence, Lapatinib's specific action on HER2 makes it an effective treatment option for breast cancer, distinguishing it from the therapies used for the other types of cancer mentioned.