Low Total Lymphocyte Count Is Associated with Poor Survival in Patients with Resected Pancreatic Adenocarcinoma Receiving a GM-CSF Secreting Pancreatic Tumor Vaccine

Background. Low total lymphocyte count (TLC) and lymphocyte-to-neutrophil ratio have been found to be poor prognostic indicators in several different tumor types at various stages. Although immune-based therapies are under rapid development, it is not known whether baseline complete blood counts, particularly lymphocytes, are associated with the clinical outcomes of patients receiving immunotherapies. Methods. We performed a retrospective analysis of complete blood count for 59 patients enrolled onto a phase II trial evaluating the integration of an adjuvant immunotherapy-irradiated granulocyte-macrophage colony-stimulating factor (GM-CSF) secreting allogeneic pancreatic tumor vaccine (GVAX)-with standard chemoradiation. Results. After adjusting for nodal status, individuals with a TLC of <1,500 cells/mm(3) (10 patients) had significantly higher risk, both in terms of overall survival (OS) [adjusted hazard ratio 2.63, 95 % confidence interval (CI) 1.22-5.67, p = 0.013] and progression-free survival (adjusted hazard ratio 3.07, 95 % CI 1.03-6.93, p = 0.003), compared to those with a TLC of <= 1,500 cells/mm(3) (49 patients). Adjuvant chemoradiation significantly reduced lymphocyte counts from baseline values. Patients with suppression of their lymphocytes to <500 cells/mm(3) after chemoradiation also had shorter disease-free and OS. Conclusions. Immunosuppressive conditions associated with surgical procedures and chemoradiation may affect the efficacy of immunotherapy.