Expression of PD-L1 in Chinese Patients with Common Cancers

Background PD-L1 immunohistochemistry (IHC) data in China was less reported. We systematically investigated PD-L1 IHC data of Chinese patients generated by Origimed. Methods PD-L1 was stained using IHC on cancer samples from 2060 Chinese patients in Origimed since 2017. Written informed consent was obtained from each patient. IHC staining was performed on FFPE tissue sections using anti-PD-L1 antibody 28-8. Tumor Proportion Score (TPS) was applied on all the samples. We investigated PD-L1 TPS in lung adenocarcinoma (n = 893), lung squamous carcinoma (n = 172), liver cancer (n = 404), esophageal cancer (n = 186), colorectal cancer (n = 166), pancreatic cancer (n = 136) and gastric cancer (n = 103). We then further applied PD-L1 combined positive score (CPS) on the 103 gastric cancer samples. All the slides were reviewed by the same senior pathologist. 95% confidence interval (CI) was obtained by bootstrap. Information entropy (Shannon’s formula) was measured in natural units. Results The highest proportion of PD-L1 TPS > = 1% was observed in lung squamous carcinoma (49%; 95% CI: [43%, 59%]), followed by lung adenocarcinoma (25%; 95% CI: [22%, 28%]), liver cancer (14%; 95% CI: [11%, 18%]), esophageal cancer (12%; 95% CI: [8.1%, 17%]), pancreatic cancer (11%; 95% CI: [5.9%, 16%]), gastric cancer (7%; 95% CI: [1.9%, 12%]) and colorectal cancer (4%; 95% CI: [1.2%, 6.6%]). The proportion of PD-L1 CPS > = 1 for gastric cancer was 17% (95% CI: [9.7%, 24%]). In gastric cancer, information entropy of TPS and CPS was 0.40 and 0.78, respectively. Conclusions The proportion of PD-L1 TPS > = 1% in Chinese lung squamous cell carcinoma (49%) was much higher than that in lung adenocarcinoma (25%). PD-L1 CPS contained more information than TPS in gastric cancer. Thus, we recommend applying CPS to gastric cancer in China. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure X. Pan: Full / Part-time employment: Origimed. Y. Dai: Full / Part-time employment: Origimed. D. Chen: Full / Part-time employment: Origimed. K. Wang: Full / Part-time employment: Origimed. X. Dong: Full / Part-time employment: Origimed. All other authors have declared no conflicts of interest.