The approval was based on the finding from a phase II clinical trial (NCT03248492), which showed that DS-8201a exert durable antitumor activity in patients who had already received treatment with T-DM1 for their metastatic or unresectable HER2-positive breast cancer and the recommended dose is 5.4 mg/kg given once every 3 weeks (Modi et al., 2020). The gene discussed is ERBB2; the disease is breast carcinoma.