The anti-CLDN18.2 ADC and anti-CLDN18.2 CD3 Bispecific Inhibit tumor growths of Pancreatic Pan-1907 and Gastric CTG-1010 PDX. Anti-CLDN18.2 ADC with cleavable linker and DAR4 demonstrated dose-dependent efficacy against an established gastric and pancreatic patient-derived xenograft models after administering a single IV dose of Anti-CLDN18.2 ADC or Negative control (NNC) ADC 50 days (Pancreatic Pan-1907) or 46 days (Gastric CTG1010) after tumor inoculation. (a,b) Anti-CLDN18.2 CD3 bispecific and diabody were also efficacious at all doses tested in an established gastric patient-derived xenograft model. (c) All data shown as mean ± SEM. Tumor growth was monitored by caliper twice-weekly. All studies were performed in immune compromised NSG mice with n = 4–5 mice per group. Statistics represent two-way ANOVA analysis, all groups compared to NNC (for ADC, a,b) or αCD3-Stumpy (for bispecific, c) ****p < 0.0001).