PD-L1 expression and type-I interferon response in non-small cell lung cancer

Background & objective: PD-1/PD-L1 inhibitors represents a breakthrough in the treatment of non-small cell lung cancer (NSCLC), but there are significant differences in treatment effectiveness, even in PD-L1-positive tumors. PD-L1 expression can be attributed to several factors, including a response to type-I interferon, which generally has many anti-tumor effects. The purpose of this study was to investigate the relationship between PD-L1 expression and type-I interferon response in lung carcinomas.
Methods: We examined the immunohistochemical expression of PD-L1 and MxA (type-I interferon-stimulated gene) in tissue microarrays with 106 different NSCLC cases, assessed by both the percentage of positive tumor cells (TPS) and H-score (0-300).
Results: No correlation was found between PD-L1 and MxA, either as TPS vs H-score (R²=0.06), or in treatment-relevant categories (<1%, 1-24%, 25-49%, 50%-) that apply in Denmark. 7 out of 16 cases with TPS>50% were MxA-negative.
Conclusions: We found no correlation between type-I interferon response and PD-L1 expression in NSCLC. The identification of a group of patients with high PD-L1 expression but without type-I interferon response may suggests a potentially beneficial effect of interferon-stimulating treatments for this subset of NSCLC patients, but further investigation is required.