Abstract
4131 Background: We previously reported the prognostic and predictive utility of pretreatment serum PD-L1 in the CCTG MA.31 serum bank (SABCS 2018, abstr PD3-10). IL-8 (CXCL8) is a pro-inflammatory cytokine that binds to CXCR1 and CXCR2 and promotes tumor immune escape and progression. High serum IL-8 levels are associated with poor prognosis in many cancers, and have recently been reported to predict for reduced OS to nivolumab in lung cancer and melanoma (ASCO 2018, abstr #3025). In this study, we retrospectively evaluated combined pretreatment serum IL-8 and PD-L1 on overall survival (OS) from a phase III randomized pancreatic cancer trial of first-line therapy (octreotide + 5-FU vs. 5-FU) that had reported no significant OS difference between treatment arms. Methods: This study had 147 patients with serum available for this retrospective biomarker analysis from an advanced pancreatic cancer phase III clinical trial.TheELLA immunoassay platform (ProteinSimple, San Jose, CA) was utilized to quantitate serum levels of IL-8 and PD-L1. Kaplan-Meier life table analysis was used to correlate serum biomarkers with overall survival (OS). Results: In univariate analysis, pretreatment serum IL-8 was a significant biomarker as a continuous variable (HR = 1.004; p = 0.012) and trended significant at the median cutpoint (HR = 1.379; p = 0.098) for OS, however serum PD-L1 was not significant at any cutpoint. When serum PD-L1 and IL-8 levels were analyzed as combined biomarkers (median cutpoints), the serum IL-8 high / PD-L1 high cohort had a significantly shorter OS vs the serum IL-8 low / PD-L1 low cohort (HR = 1.816; p = 0.017). Conclusions: In this phase III randomized clinical trial in advanced pancreatic cancer, pretreatment serum IL-8 was a significant biomarker for OS, but serum PD-L1 was not. Higher combined pretreatment serum levels of PD-L1 and IL-8 (both biomarkers high vs. both low) were prognostic for reduced OS in this phase III pancreatic cancer trial. Further study of circulating IL-8 and PD-L1 is warranted in pancreatic cancer for evaluation of targeted and investigational therapies, including the immune checkpoint inhibitors and anti-IL8 therapy.
Published Version
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