AUR103

The study will have a dose escalation part (Phase 1b) and a randomized part (Phase 2). In Phase 1b, patients diagnosed with advanced HER2 positive gastric/gastroesophageal adenocarcinoma will be enrolled in a 3 + 3 design dose escalation manner to evaluate the safety, efficacy, PK/PD of AUR103 Calcium when administered in combination with Trastuzumab and CAPOX (capecitabine and oxaliplatin). Phase 2 is a randomization study. The primary objective of the phase 2 study is to assess the efficacy of AUR103 Calcium when administered in combination with Trastuzumab and CAPOX (capecitabine and oxaliplatin). The phase 2 of the study will be conducted after Phase 1b.