Nazartinib, also known as EGF816 or NVS-816, is primarily used in the treatment of non-small cell lung cancer (NSCLC), particularly in cases where the cancer cells have specific mutations in the epidermal growth factor receptor (EGFR). It is an EGFR tyrosine kinase inhibitor that targets and blocks the activity of mutated EGFR proteins, which are often responsible for the uncontrolled growth of cancer cells. This makes it effective in slowing tumor progression and improving patient outcomes. Additionally, Nazartinib has been investigated for its potential in treating other cancers with EGFR mutations, such as glioblastoma. Its ability to penetrate the blood-brain barrier also makes it a promising candidate for treating brain metastases associated with NSCLC.