Longitudinal follow-up of a prospective phase II trial of neoadjuvant gemcitabine and oxaliplatin in patients with resectable pancreas adenocarcinoma reveals distinct patterns of survivorship

Background: Neoadjuvant chemotherapy has emerged as a promising treatment strategy for patients with resectable pancreatic ductal adenocarcinoma. We have conducted and previously reported 18-month survival from a single-institution non-randomized phase II trial of neoadjuvant gemcitabine and oxaliplatin in patients with resectable pancreatic ductal adenocarcinoma. We sought to report updated survival after longitudinal follow-up from this prospective study. Methods: After confirming absence of metastatic disease with axial imaging and diagnostic laparoscopy, enrolled patients received 4 cycles of neoadjuvant gemcitabine and oxaliplatin. Patients whose tumors remained resectable on restaging underwent diagnostic laparoscopy and resection, followed by 5 cycles of adjuvant gemcitabine. Overall survival (OS) was calculated from trial initiation to death/last follow-up. Recurrence-free survival (RFS) was calculated among resected patients from date of surgery. OS and RFS were estimated using Kaplan-Meier methods. The contribution of recurrence to OS was investigated as time-dependent covariate in the Cox proportional hazards model. Relative proportions of CD3+, CD4+, CD68+, and FoxP3+ tumor-infiltrating lymphocytes (TIL) in resected specimens were quantified by immunofluorescence, and compared between longer-term resected (LTR; >median OS of intent-to-treat cohort) and shorter-term resected (STR;