Background: High mortality associated with pancreatic ductal adenocarcinoma (PDA) warrants research into prognostic factors. We examined the relationship between the daily rate of change of CA19-9 over the first 90 days of treatment (DRC90) and pretreatment levels of neutrophils, lymphocytes, and platelets with overall survival (OS) and progression free survival (PFS) in patients with stage IV PDA that received chemotherapy. Methods: We retrospectively evaluated 102 locally advanced and metastatic PDA patients treated at KU Cancer Center between Jan 2011 and Sep 2019. We compared the ratio of pretreatment absolute neutrophil count to pretreatment absolute lymphocyte count (NLR) and the ratio between pretreatment platelet count to pretreatment absolute lymphocyte count (PLR) with OS and PFS. We also compared DRC90 to OS and PFS. Log-rank trend test using the mean of NLR, PLR, and DRC90 as the threshold for two groups within each variable. Results: Baseline demographics are shown in the table. Pts with ≥ mean NLR (4.6) had significantly lower OS [p = 0.0444] and PFS [p = 0.0483] than Pts below the mean. Pts with PLR ≥ mean (3.9) did not have significantly different OS [p = 0.507] or PFS [p = 0.643] than Pts below the mean. Pts with DRC90 ≥ mean (-1%) did not have significantly different OS [p = 0.342] or PFS [p = 0.313] than Pts below the mean. Conclusions: Pts with NLR ≥ mean (4.6) had significantly lower OS and PFS than Pts with NLR below the mean. This implies the possibility of NLR as a prognostic marker in PDA that could guide treatment approach but needs validation in a larger cohort.