OBJECTIVES: To characterize PD-L1 and other biomarker expression in advanced Urothelial (UC), Esophageal (EC), and Head and Neck Squamous Cells (HNSCC) carcinomas in archived tissue samples from two institutions of Colombia.

METHODS:

This was a descriptive, retrospective, and observational cohort study. PD-L1 and P16 protein (only for HNSCC located in oropharyngeal sites) expression levels were measured by a validated immunohistochemistry (IHC) method using 22C3 and E6H4 monoclonal antibodies, and the Combined Positive Score (CPS) methodology. Demographics and other variables as HER2 expression in EC were collected from medical records and analyzed.

RESULTS:

One hundred eighty-one tissue samples (59 from UC, 22 from EC and 100 from HNSCC) were collected for biomarker testing. The median age of patients was 72.0 years for UC, 67.5 for EC and 61.5 for HNSCC, with the majority being men (78.0%, 90.9% and 79%, respectively). Regarding biomarkers 22.0% (n=13) of the UC tissue samples had PD-L1 CPS score ≥10 and 54.2% (n=32) had a PD-L1 ≥1; while 22.7% (n=5) of the EC group had a PD-L1 score ≥10 and 40.9% (n=9) had a PD-L1≥1. Positive HER2 expression was found in 23.0%(n=5) of EC cases. On the other hand, 27.0% (n=27) of HNSCC tissue samples had a PD-L1 CSP score ≥20 and 73.0% (n=73) had a PD-L1 ≥1, while 47.0% (n=47) of samples were p16 positive.

CONCLUSIONS:

he PD-L1 expression prevalence in a cohort of the Colombian population has been studied for the first time. The prevalence of PD-L1 CPS score ≥10 was less for UC and EC samples compared with previous reports for these tumors in other clinical trials as well as for HNSCC with a CPS score of ≥20. Further studies are needed, focused on evaluating PD-L1 expression in Colombian patients influenced by their own environment and genetics, to define characteristics that support decision-making for tumor treatment.