Abstract 1006P
Background
PD-L1 expression and tumor mutational burden (TMB) may predict response in patients treated with immunotherapy; however, their prognostic significance in HCC patients treated with surgery remains unclear. We aimed to characterize PD-L1 prevalence and explore the relationship between PD-L1, TMB and overall survival (OS) among patients in Denmark and Korea.
Methods
This study used archived FFPE tumor and clinical records from 198 patients undergoing surgical treatment, prior to systemic therapy, at either Samsung Medical Center, Aarhus University Hospital or Copenhagen University Hospital. PD-L1 was measured using DAKO’s IHC 22C3 pharmDx assay. PD-L1 positivity was defined as a combined positive score (CPS) ≥1. TMB status, determined via whole exome sequencing, was dichotomized as high/low based on study-specific distributions with the highest quintile classified as TMB-high (H). OS was analyzed using Kaplan-Meier methods and log-rank tests to compare survival curves. OS was calculated from surgery until death for any reason.
Results
Median age was 52 in Korea and 65 in Denmark; 76% of the cohort was male and 96% of tissue was collected via resection. Eighty-six percent of patients in Denmark were stage I/II at surgery compared to 23% in Korea. All Denmark patients were Barcelona Clinic Liver Cancer (BCLC) stage 0 or A, compared to Korea where 75% were BCLC C. PD-L1 CPS≥1 prevalence was 36% and 54% in Denmark and Korea, respectively. In Korea, median OS among patients with CPS≥1 was 29 months (m) compared to 46m in CPS<1 (log-rank p=0.01). In Denmark, median OS was similar between PD-L1 subgroups (CPS<1=72m, CPS≥1=79m; p=0.6). TMB-H status was associated with longer OS in Korea (TMB-H=58m, TMB-L=29m; p=0.09) but not Denmark (TMB-H=61m, TMB-L=72m; p=0.7).
Conclusions
Our study suggests that PD-L1 CPS<1 and TMB-H-status may be associated with longer survival among HCC patients undergoing surgical treatment in Korea, a trend that was not observed in Denmark. Differences in patient characteristics, etiology, and treatment pathways may explain regional differences in OS and the role of biomarkers in HCC. Further investigations in larger, more diverse patient populations are warranted.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Merck & Co., Inc.
Funding
Merck & Co., Inc.
Disclosure
M.A. Marsico, A.B. Siegel, A. Webber: Shareholder/Stockholder/Stock options, Full/Part-time employment: Merck & Co. X. Liu, A. Kachurak: Full/Part-time employment: Merck & Co.All other authors have declared no conflicts of interest.