Neoadjuvant Chemotherapy affects PD-L1-expression
Many studies have shown that various factors, such as chemotherapy, may affect the expression of PD-1, PD-L1, PD-L2. Sun W et al. (abstract JCSE 01.16) showed that the expression of PD-L1 was up-regulated after NAC when using 5%, 10%, 20% expression threshold. No correlations existed between the variation of PD-1, PD-L1, PD-L2 and tumor shrinkage rate, interval from the end of NAC to operation, pathological type, gender, smoking or not.
In this study, tumor samples were obtained from 26 patients with confirmed primary lung cancer prior to and after NAC (platinum-based). Expression of PD-1, PD-L1, PD-L2 in lung cancer tumor specimens were assessed by immunohistochemistry (IHC), using 5 %, 10 %, 20 %, 30 %, 50 % expression thresholds to define PD-1, PD-L1, PD-L2 positive status, respectively. The variation of PD-1, PD-L1, PD-L2 prior to and after NAC were evaluated by Matching chi-square test. Spearman’s rank correlation and non-parametric test were used to calculate the relationship between the changes of PD-1, PD-L1, PD-L2 and tumor shrinkage rate, interval from the end of NAC to operation, pathological type, gender, and smoking status.
Using a 5 %, 10 %, 20 % expression threshold to define PD-L1 positive status, 65.4 % (17/26), 53.8 % (14/26), 42.3 % (11/26) were found to be PD-L1 positive prior to NAC, and 92.3 % (24/26), 80.8 % (21/26), 69.2 % (18/26) expressed PD-L1 after NAC. PD-L1 was up-regulated after NAC (p = 0.003, p = 0.016, p = 0.016). However, when using a 30 % and 50 % threshold, there were no statistically significance differences. The expression of PD-1 and PD-L2 was not altered before and after NAC. Furthermore, there was no association between the changes of PD-1, PD-L1, PD-L2 and pathological type, interval from the end of NAC to operation, gender, or smoking status.
Sun W et al., abstract JCSE 01.16 – Altered Expression of Programmed Death-1 Receptor (PD-1) and its Ligand PD-L1, PD-L2 after Neo-Adjuvant Chemotherapy in Lung Cancer