ERBB2 and gastroesophageal junction adenocarcinoma: We conducted this phase Ib study including two cohorts, wherein ADX was combined with an oral fluoropyrimidine S-1 plus cisplatin (SP)24 or S-1 plus oxaliplatin (SOX)25,26 as the first-line treatment for Japanese patients with human epidermal growth factor receptor 2 (HER2)-negative advanced gastric or GEJ adenocarcinoma (ClinicalTrials.gov identifier: NCT02862535).