PD-L1 Expression in Colorectal Carcinoma: A Comparison of 3 Scoring Methods in a Cohort of Jordanian Patients

Abstract

Anti–programmed death-ligand 1 (PD-L1) treatments can improve colorectal carcinoma (CRC) survival; however, there is still controversy regarding the relationship between PD-L1 expression and the outcome of immunotherapeutic treatment and survival. The discrepancies are partly caused by the lack of a unified scoring system. This retrospective, cross-sectional study evaluated PD-L1 by immunohistochemistry in 127 CRC cases and compared the 3 scoring systems used to assess PD-L1: Tumor Percentage Score (TPS), Combined Positive Score (CPS), and immune cell (IC) score. Correlations were calculated using the χ2 test. Kaplan-Meier curves with the Log-rank test were used to measure the contribution of PD-L1 expression to survival. PD-L1-positive rate were 29.9%, 57.5%, and 55.9% based on TPS, CPS, and IC score, respectively. TPS showed a better correlation with the clinicopathologic features being significantly higher with young age, T4, and adenocarcinomas (compared with mucinous/signet ring). TPS also showed an increasing trend with higher grade, lymph node stage, and male sex, although these variables were not significantly associated with PD-L1 expression. There was no correlation between PD-L1 expression and mismatch repair protein status in the 3 scoring methods. The probability of survival was higher for PD-L1-negative cases in the first 60 months after surgery if scored by the TPS method (P=0.058). Future efforts correlating PD-L1 status with response to treatment are needed to decide on the best scoring method to be used for making therapy decisions.

Evaluation of PD-L1 Expression in Colorectal Carcinomas by Comparing Scoring Methods and Their Significance in Relation to Clinicopathologic Parameters

“…These results suggest that the expression assessment in tumor cells alone may not reflect the overall immune tolerance in the tumor [18]. With many tumor-infiltrating lymphocytes (TILs), the CPS values are more significant at >50% compared to little or no tumor infiltration, which is in agreement with previously published studies [20,21]. These results once again support the results from previous studies and the conclusions that lymphocytes infiltrating the tumor, regardless of the type of T-or B-cells, play a significant role in the immune microenvironment, and further research on the resolution of their role could be the basis for the realization of personalized immunotherapy for patients with CRC [22].…”

“…Two or more proteins are defective in 19 (18.6%) samples, while one is defective in 17 (16.7%). This is a higher percentage compared to the reported results of 15% [21]; however, studies from Egypt (36 and 37%) and Jordan (22%) report higher percentages [21,22]. This study did not find a significant association between CPSs and MMR status.…”