Afatinib dimaleate is used as a targeted therapy in the treatment of non-small cell lung cancer (NSCLC), particularly in patients with specific epidermal growth factor receptor (EGFR) mutations such as exon 19 deletions or exon 21 (L858R) substitutions. It acts as an irreversible inhibitor of the EGFR family, including HER1/EGFR, HER2, and HER4, blocking signaling pathways that drive cancer cell growth and survival. This makes it effective in slowing tumor progression and improving progression-free survival in eligible patients.

It is commonly prescribed as a first-line treatment for metastatic NSCLC without concomitant T790M mutations or in patients who have not previously received EGFR tyrosine kinase inhibitors (TKIs). Taken orally, it offers a non-chemotherapeutic option with a more tailored approach based on genetic profiling of the tumor. Additionally, it is being investigated for other EGFR pathway-related cancers, such as gallbladder cancer or head and neck cancer, but these remain in research stages and are not primary indications.