Real-world characterization of PD-L1 expression in patients with advanced esophagogastric adenocarcinoma in Spain

Epidemiological data from Sapin are lacking, especially in a publication relating Spanish data and prevalence of programmed cell death ligand-1 (PD-L1) expression. This study aimed to evaluate the prevalence of PD-L1 expression by Combined Positive Score (CPS) ≥ 5 in patients with advanced esophagogastric adenocarcinoma (aEGAC) in Spain.

This observational, retrospective, and multicenter study collected sociodemographic and clinical data from adult patients with locally advanced unresectable, recurrent, or metastatic EGAC across 21 centers in the AGAMENON-SEOM registry. CPS PD-L1 expression was centrally analyzed using the IHC 28-8 pharmDx.

A total of 166 patients were included, with 144 valid and evaluable samples. The primary tumor locations were stomach (70.1%), gastroesophageal junction (19.4%), and esophagus (10.4%). At diagnosis, 84.0% had synchronous metastatic disease, 4.9% had unresectable locally advanced disease, and 11.1% had recurrent disease. PD-L1 CPS ≥ 5 was observed in 41.7% of the patients (95%CI, 34.3-50.4%). Prevalence by tumor type was 41.6% (95% CI, 32.0-51.2%) in gastric adenocarcinoma, 35.7% (95% CI, 18.0-53.5%) in gastroesophageal junction adenocarcinomas, and 60.0% (95% CI, 35.2-84.8%) in esophageal adenocarcinoma. PD-L1 CPS ≥ 5 was found in 42.9% (95% CI, 6.2-79.5%) of patients with unresectable locally advanced disease, 43.0% (95% CI, 34.2-51.8%) of those with metastatic disease, and 37.5% (95% CI, 13.8-61.2%) of those with recurrent disease.

This is the first study to report the real-world prevalence of PD-L1 expression in patients with aEGAC in clinical practice in Spain. These findings underscore the importance of understanding PD-L1 prevalence in the Spanish population and investigating discrepancies with previous studies.