Circulating and Tumor-Associated Neutrophils Function as a Powerful Biomarker for Response to Chemoradiation in Locally Advanced Cervical Cancer.

Purpose/objective(s) The role of the immune system in mediating the cytotoxic effects of chemoradiotherapy, remains incompletely understood. The integration of immunotherapies into treatment will require insight into features and timing of immune microenvironment associated with treatment response. Here, we investigate the role of circulating and tumor-associated neutrophils (TANs) as potential agents and biomarkers for disease-related outcomes in LACC. Materials/methods Hematologic parameters for two patient cohorts, a retrospective clinical and a prospective translational cohort, were obtained at baseline, weekly during chemoradiation, and at first follow up visit. Baseline, mean and lowest on-treatment values for platelets, hemoglobin, absolute neutrophil count (ANC), and absolute lymphocyte count (ALC) were correlated with disease-related outcomes using univariate (UVA) and multivariable analyses (MVA). Circulating neutrophils were isolated from peripheral blood mononuclear cells (PBMCs) and TANs were isolated from tumor tissue via a novel serial cytobrush sampling assay. The samples were analyzed by flow cytometry and correlated via linear regression analysis. Results A total of 151 patients were included in the retrospective cohort with a median follow up of 33 months. Of the tested hematologic parameters elevated on-treatment mean ANC (mANC) was associated with lower rate of local control on UVA (HR 1.314; 95% CI, 1.102-1.567, P = 0.002) and MVA (HR 1.369; 95% CI, 1.104-1.697, P = 0.004). mANC was the only hematologic factor associated with lower survival on MVA (HR 1.255; 95% CI, 1.048-1.502, P = 0.013). mANC was not associated with a difference in distant metastases (HR 1.002; 95% CI, 0.810-1.241, P = 0.984). In an independent, prospectively-accrued cohort, mANC was similarly associated with lower OS (HR 1.636, 95% CI, 1.172-2.285, P = 0.004) on UVA. Analysis of the tumor-associated neutrophils (TAN) demonstrated that neutrophils constituted 22.4% (standard error [SE] 3.96%) of all live leukocytes in the tumor at baseline, which steadily increased and peaked at 41.3% (SE 7.8%) at week 5 of treatment (P = 0.027). Neutrophils constituted of 78.2% (SE 4.6%) of live leukocytes in PBMCs at baseline, and steadily decreased with a nadir of 65.7% (SE 8.5%) at week 5 of treatment (P = 0.137). Regression analysis showed an inverse relationship between circulating neutrophils and TANs, with the strongest correlation observed at week 5 of chemoradiation (R2 = 0.29). Conclusion These findings implicate neutrophils in chemoradiation treatment resistance, identify on-treatment mean neutrophil count as a robust and optimal predictor of disease-related outcomes, and establish an inverse relationship between circulating and tumor-associated neutrophils. Author disclosure O. Gjyshi: None. A. Grippin: Student; University of Florida. D. Boyce-Fappiano: None. A. Jhingran: American Board of Radiology. L.L. Lin: Employee; VA Hospital. Research Grant; AstraZeneca. Travel Expenses; AstraZeneca. P.J. Eifel: Travel Expenses; National Cancer Center Network. Stock; Apple Computer. M.M. Joyner: Consultation with executive management and participation in board meetings; Frontline Bioenergy. J. Sastry: None. K. Court: None. T. Solley: None. V. Hegde: None. L. Colbert: None. A.H. Klopp: Research Grant; MD Anderson Cancer Center SPORE Grant.