Background: PD-1 inhibitors have transformed the treatment landscape for patients (pts) with many advanced malignancies. Combination therapy with PD-1 inhibitors for cancer is a trend. However, Biomarkers for the efficacy of combination therapy remains unknown. In order for the benefited population to be screened out, biomarkers need to be established. we will conduct the following study, to explore the IFN-α, IFN-γ, IL-2 combined with TNF-α for predicting efficacy of PD-1 inhibitors combination therapy. Methods: Using postoperative without lesions as control group (n=7). Pts with lesions as the experimental group (n=66). 27 of 66 pts received chemoradiotherapy (group A), 39 of 66 pts received PD-1 inhibitors combined with therapy (group B). IFN-α, IFN-γ, IL-2, TNF-α in peripheral blood of all pts were measured using flow cytometry. Results: 1) There was significant difference in proportion above normal concentrations (ANCs) of IFN-α between two groups (57.1% vs 43.5%, P<0.05), but there was no significant difference in IFN-γ, IL-2 and TNF-α between two groups (IFN-γ 57.1% vs 52.2%, IL-2 14.3% vs 5.8%, TNF-α 42.9% vs 43.5%, P>0.05). 2) The normal ratios of IFN-α, IFN-γ and TNF-α in group B was significantly higher than that in group A (IFN-α 64.1% vs 51.9%, IFN-γ 59% vs 37%, TNF-α 69.2% vs 44.4%, P<0.05). The proportion ANCs of IFN-α, IFN-γ, and TNF-α were lower in group A (IFN-α 35.9% vs 63%, P>0.05; IFN-γ 41% vs 63%, P<0.05; TNF-α 30.8% vs 55.6%, P<0.05). However, the proportion ANCs of IL-2 detection was lower (7.4% vs 5.1%). 3) In group B, 21 of 39 pts were evaluable. ORR was 52.4% (11/21) and DCR was 85.7% (18/21). The proportion ANCs of IFN-α, IFN-γ and TNF-α in the pts with PR was higher than that with SD (IFN-α 37.5% vs 28.6%, IFN-γ 37.5% vs 28.6%, TNF-α 50% vs 38.8%, P<0.05). 4) We found that the coincidence rate of IFN-α+ IFN-γ and IFN-α+ IFN-γ+TNF-α was higher in group B (Table). Conclusions: Our results suggest that the proportion ANCs of IFN-α, IFN-γ, and TNF-α in the pts with lesions were lower than that without lesions, it may be the decrease of immune function with lesions. There was positive correlation between proportion ANCs of IFN-α, IFN-γ and TNF-α and efficacy in these pts. IL-2 was not used as a routine detection indicator. The coincidence rate of IFN-α, IFN-γ combined with TNF-α was higher, it may help predict the outcome of PD-1 inhibitors combination therapy in pts with solid cancers, and helpful to screen the benefit population. Further study is needed.

*IFN-α+IFN-γ, IFN-α+IFN-γ+TNF-α: group A; others: group B.