Background
PD-1 checkpoint inhibitors are novel therapeutic agents in colorectal cancer (CRC). Immunohistochemical staining for CD274 assessment is standardised in upper GI cancer, but not in CRC.
Conclusion
CD274 does not appear useful as a prognostic marker. As a marker of response to anti-PD-1 therapy, assessment methodology requires standardisation. As the Combined Positive Score (CPS) is used in upper GI cancer, this seems a logical method to adopt. Thresholds for CRC remain to be determined.
Methods
Methodologies of relevant studies were scrutinized and meta-analysis of survival and CD274/PDCD1 performed. Furthermore, anti-PD-1 therapy clinical trial
Results
24 studies were included. CD274 on immune cells was associated with good prognosis. CD274 on tumour cells has heterogenous outcomes and does not meet requirements of a prognostic marker. As a marker of response to anti-PD-1 therapy, CD274 assessment is not standardised in CRC.