In addition, the FDA granted this drug breakthrough therapy status in 2020 for treating patients suffering from metastatic non-small cell lung cancer (NSCLC) with a HER2 mutation after platinum-based therapy, as well as priority review for the treatment of HER2-positive metastatic adenocarcinoma of the stomach or gastroesophageal junction [23,68,96]. The gene discussed is ERBB2; the disease is non-small cell lung carcinoma.