TAP and CPS Scores Show High Concordance in Predicting Outcomes for Tislelizumab-Treated Gastric and Esophageal Cancers

In a pooled analysis of baseline tissue samples from RATIONALE-305, RATIONALE-302, and RATIONALE-306, PD-L1 expression measured by Tumor Area Positivity (TAP) and Combined Positive Score (CPS) demonstrated significant agreement (Cohen's Kappa 0.64–0.85) at ≥1%, ≥5%, and ≥10% cutoffs, with similar stratification of overall survival, progression-free survival, objective response, and duration of response in gastric/gastroesophageal junction adenocarcinoma and esophageal squamous cell carcinoma patients treated with tislelizumab.

This study confirms that TAP and CPS are clinically interchangeable immunohistochemistry measures of PD-L1 expression, providing equivalent predictive value for treatment outcomes in these patient populations.