Background: Within the next decade, pancreatic ductal adenocarcinoma (PDAC) is expected to rise to the second leading cause of cancer-related mortality. To increase the survival, various peri-operative treatments have been tested, and adjuvant FOLFIRINOX or gemcitabine plus capecitabine is now standard of care after surgical resection for localized PDAC. Even with superior survival among various disease extent of PDAC, resectable PDAC still shows poor outcomes with surgery followed by adjuvant chemotherapy. This phase II study is investigating the role of modified-FOLFIRINOX as neoadjuvant treatment for resectable PDAC. Methods: This study is a phase II, multi-institutional, single-arm trial to evaluate the efficacy and safety of modified-FOLFIRINOX in resectable PDAC. The main inclusion criteria are histologically confirmed PDAC; resectable PDAC confirmed by both computed tomography (CT) and magnetic resonance imaging (MRI) according to NCCN guideline resectability criteria (no arterial tumor contact to celiac axis, SMA or CHA; no tumor contact with SMV or PV or ≤180° contact without vein contour irregularity); no previous treatment (surgery or chemotherapy); ECOG 0 or 1; and adequate organ function. Patients receive oxaliplatin 85 mg/m² D1 + leucovorin 400mg/m² D1 + irinotecan 150 mg/m² D1 + 5-FU 2,000 mg/m² 46h continuous infusion, every other week for 6 cycles (12 weeks). Response assessments are performed every 6 weeks using the RECIST criteria version 1.1. Baseline MRI, PET-CT scan before treatment, and pre-surgery MRI after 6 cycles are mandatory. The primary endpoint was R0 resection rate. Secondary endpoints included progression-free survival, overall survival, disease-free survival, objective response rate, safety, resection rate, and correlative biomarker exploration. The study will enroll up to 27 patients and is currently recruiting at four sites in South Korea. As of September 2021, 20 patients have been enrolled. Clinical trial information: KCT0004421 (Registration ongoing for clinicaltrials.gov).