Used in the treatment of early-stage and metastatic HER2-positive breast cancer. It works by irreversibly inhibiting the tyrosine kinase activity of the HER2 and EGFR (HER1) receptors, which are involved in tumor cell growth and survival. Neratinib is typically prescribed after surgery and completion of trastuzumab-based therapy to reduce the risk of cancer recurrence. It has also been studied in combination with other chemotherapeutic agents for advanced disease. Its oral formulation allows for convenient long-term administration in adjuvant settings.