Vactosertib With Nal-IRI/FL in Metastatic Pancreatic Ductal Adenocarcinoma.

* Number of patients : Total 24 patients (6-12 patients in phase 1 part and 12 patients in expansion cohort ) * Treatment : * Vactosertib\* 100-300 mg bid for 5 days * Liposomal Irinotecan (Onivyde) 70mg/m2 on D1 * LV 200mg/m2 IV bolus on D1 * 5-FU 2400mg/m2 CIV over 46 hours on D1 * Vactosertib will be kindly provided by MedPacto. * Disease evaluation: Tumor assessment will be conducted at screening and before Day 1 of every third cycle starting with Cycle 4 * Period : Approximately 24 months from the date of Institutional Review Board (IRB) approval * Primary endpoint : To determine recommended phase 2 dose and to evaluate the safety of vactosertib in combination with nal-IRI/FL in patients with metastatic pancreatic ductal adenocarcinoma (PDAC) who have failed first-line gemcitabine and nab-paclitaxel * Secondary endpoint : * Progression-Free Survival (PFS) (RECIST 1.1 criteria) * Overall Survival (OS) * Objective Response Rate (ORR) (RECIST 1.1 criteria) * Disease Control Rate (DCR) (RECIST 1.1 criteria) * Exploratory endpoint * Pharmacokinetic assessment: before treatment, post treatment 1.5h, 4.5h, and 8hPharmacodynamic assessment: to evaluate changes in the amount of p-SMAD in PBMC. * Biomarker analysis in pre-treated and post-treated tumor samples