ABSTRACT
BACKGROUND:
Anti-programmed
death-1/programmed
death-
ligand 1 (PD-1/PD-L1)
immunotherapy has demonstrated promising results on
gastric cancer (GC). However, PD-L1 can express differently between metastatic sites and primary
tumors (PT).
AIM:
To compare PD-L1 status in PT and matched
lymph node metastases (LNM) of GC
patients and to determine the correlation between the PD-L1 status and clinicopathological characteristics.
METHODS:
We retrospectively reviewed 284 GC
patients who underwent D2-
gastrectomy. PD-L1 was evaluated by
immunohistochemistry (
clone SP142) using the combined positive score. All PD-L1+ PT staged as pN+ were also tested for PD-L1 expression in their LNM. PD-L1(-) GC with pN+ served as the comparison group.
RESULTS:
Among 284 GC
patients included, 45 had PD-L1+ PT and 24 of them had pN+. For comparison, 44 PD-L1(-) cases with pN+ were included (sample loss of 4 cases). Of the PD-L1+ PT, 54.2% (13/24 cases) were also PD-L1+ in the LNM. Regarding PD-L1(-) PT, 9.1% (4/44) had PD-L1+ in the LNM. The agreement between PT and LNM had a kappa value of 0.483. Larger
tumor size and moderate/severe peritumoral inflammatory response were associated with PD-L1 positivity in both sites. There was no statistical difference in overall
survival for PT and LNM according to the PD-L1 status (P = 0.166 and P = 0.837, respectively).
CONCLUSION:
Intra-
patient heterogeneity in PD-L1 expression was observed between the PT and matched LNM. This disagreement in PD-L1 status may emphasize the importance of considering different
tumor sites for analyses to select
patients for
immunotherapy.