Comparison of PD-L1 expression and MMR status between primary and matched metastatic lesions in patients with...

Programmed death-ligand 1 (PD-L1) and DNA mismatch repair (MMR) are considered predictive biomarkers for immunotherapy in cervical cancer. However, their expression in primary tumors and metastases does not always match affecting the course of treatment. We investigated the consistency of their expression in primary and matched recurrent/metastatic lesions from patients with cervical cancer.

Primary and matched recurrent/metastatic specimens from patients with recurrent cervical cancer (n = 194) were stained for PD-L1 and MMR (MLHI, MSH6, MSH2, and PMS2) using immunohistochemistry. The degree of consistency of PD-L1 and MMR expression in these lesions was analyzed.

The inconsistency rate of PD-L1 expression in primary and recurrent/metastatic lesions was 33.0%, and it varied between the recurrence sites. Positive PD-L1 rate in primary lesions was lower (15.4%) than that in recurrent/metastatic lesions (30.4%). The discordance rate of MMR expression between primary and recurrent/metastatic lesions was 4.1%.

We conclude that to use PD-L1 as a predictive biomarker for immunotherapy, analysis of both metastatic and primary lesions may be required. High consistency rate of MMR expression between primary and metastatic lesions suggests that testing primary lesions alone can be sufficient for guiding the course of therapy, thereby solving the difficulty of obtaining recurrent/metastatic specimens in clinic.