A Study of Trastuzumab DeRuxtecan for Patients With Advanced HER2-pOsitive GaStric or GastroesoPhageal Junction AdEnocarcinoma Who Have Received a PrIor Trastuzumab-based Regimen Accompanied by a Disease RegistrY of Patients Treated With Conventional Therapies (PROSPERITY)

Trastuzumab deruxtecan (T-DXD) as monotherapy is indicated for the treatment of adult patients with advanced HER2-positive advanced gastric or gastroesophageal junction (GEJ) adenocarcinoma who have received a prior trastuzumab-based regimen. This study will assess the effectiveness of T-DXd, patient demographic and clinical characteristics, and treatment patterns in patients with advanced HER2-positive advanced gastric or GEJ adenocarcinoma.