Beamion BCGC-1: A Phase Ib dose escalation and Phase II dose optimization, randomized, open-label, multicenter trial of oral zongertinib (BI 1810631) in combination with intravenous trastuzumab deruxtecan (T-DXd) or in combination with intravenous trastuzumab emtansine (T-DM1) for treatment of patients with advanced HER2+ metastatic breast cancer (mBC) and metastatic gastric, gastroesophageal junction, or esophageal adenocarcinoma (mGEAC)