A recent retrospective study reported the prevalence of CLDN18.2 positivity, defined as ≥ 75% of tumor cells demonstrating moderate-to-strong membranous CLDN18 staining using the on-market VENTANA CLDN18 (43-14A) Assay (VMSI/Roche), as 24.0% in a cohort of 408 evaluable patients with advanced G/GEJ adenocarcinoma from Japan [21]. Here, CLDN18 is linked to gastroesophageal junction adenocarcinoma.