160P Baseline IL-8 level as a predictive biomarker for anti-PD1 therapy in nonmelanoma skin cancers: Insights from a phase II agenonmela trial

Background: Immunotherapy has emerged as a promising treatment approach for certain nonmelanoma skin cancers (NMSC).However, further research is needed to fully understand the factors that determine which patients with NMSC are most likely to benefit from this therapy.This study aimed to evaluate serum cytokine levels as potential predictive biomarkers in NMSC patients undergoing therapy with the checkpoint inhibitor balstilimab.Methods: Thirty patients with unresectable or metastatic NMSC receiving balstilimab therapy had blood samples collected at baseline and at the radiological assessment at week 12. Serum cytokines, including sPD-L1 (B7-H1), IL-6, TNF-a, CXCL8 (IL-8), CXCL10, IFN-g, and IL-1b, were measured using the Luminex X-MAP system (Luminex 200, BIO-RAD) and the Luminex Discovery Assay, Human Premixed Multi-Analyte Kit.Results: The analysis revealed that low IL-8 levels at screening were significantly predictive of achieving complete or partial response (CR/PR) (p 0.01).Stratifying patients into low and high IL-8 screening level groups, with a threshold of 14.9 pg/ml, showed that patients in the low group achieved CR/PR more frequently (p 0.007).CXCL10 levels at screening also showed potential in differentiating patients likely to achieve CR/PR, though this result did not reach statistical significance (p 0.054).Other cytokines measured in the study did not show statistically significant associations with treatment outcomes.Conclusions: Baseline IL-8 levels may serve as a predictive biomarker for treatment response in patients with NMSC receiving anti-PD1 therapy.These findings align with previous evidence linking elevated baseline IL-8 levels to worse clinical outcomes in patients treated with immunotherapy.A limitation of this study is the small sample size, reflecting the rarity of metastatic or unresectable NMSC.Clinical trial identification: ABM_01_00004_03.