Affiliations 

  • 1 Universiti Putra Malaysia
  • 2 Universiti Kebangsaan Malaysia
MyJurnal

Abstract

Introduction: It is well known that cancer cells evade the immune system with the help of programmed cell death protein 1 (PD-L1) molecule to remain undetected, causing abnormal proliferation of T-cells. PD-L1 expression on the surface of neoplastic cells inhibits cytotoxic T-cell responses which lead to negative regulation of cytokines and proliferation of T-cells. The deleted in colorectal cancer (DCC) gene belongs to the immunoglobulin superfamily. It is a candidate of the tumour suppressor gene by regulating apoptosis. DCC assessment gives an insight into progno-sis in patients with advanced stages of CRC. Thymidylate synthase (TYMS) is a highly conserved enzyme involved in DNA synthesis. TYMS has been an important target for cancer chemotherapy because of its central, rate-limiting role in de novo synthesis of thymidylate. Expression of PD-L1, TYMS and DCC has been demonstrated to confer a prognostic value in CRC but none have been completely validated for patient care. This study aimed to determine the prognostic and predictive potential of PD-L1, TYMS, and DCC biomarkers in CRC. Methods: The expression of these biomarkers was evaluated immunohistochemically in 91 formalin-fixed paraffin-embedded (FFPE) archival tumour samples from patients that underwent surgical resection. Results: There was high expression of DCC in most cases; 84.6% (77/91). TYMS expression at a high level score was 46.2% (42/91) and at low level was 53.8% (49/91). Majority of cases had low PD-L1 expression in 93.4% (86/91) cases and high expression was detected in 6.6% (6/94) of cases. In addition, there was a significant association between TYMS expression with gender (P < 0.05) with distribution of TYMS expression detected at high level was 76.2% in male and 23.8% in female. The Kaplan-Meier survival plot showed mean overall survival in patients with PD-L1 with high expression to be 22 months, which pre-dicts better survival. TYMS low expression showed mean overall survival of 90 which also indicated better survival. DCC high expression showed mean overall survival of 90 which indicated better survival. The correlation between the biomarkers and overall survival were not statistically significant. Conclusion: The results from this study suggest that PD-L1, TYMS and DCC expression could be used as biomarkers to predict treatment outcome in CRC. PD-L1 overexpression predicts patients who could benefit from anti-PD-1 and anti-PD-L1 immunotherapy whilst TYMS low expression predicts patients who could benefit from 5-fluorouracil therapy. DCC high expression tumours predicts a better prognosis and overall survival compared to DCC-negative tumours in advanced CRC.