Liposomal Irinotecan Plus 5-FU / LV Combined With Paricalcitol in Patients With Advanced Pancreatic Cancer Progressed on Gemcitabine-based Therapy

-Standard of care drug

-Standard of care drug

-Standard of care drug

-Investigational drug

-baseline, day 1 of each cycle beginning with cycle 2

"* 5 patients in each arm will be required to undergo a mandatory tumor biopsy from the primary pancreatic site or metastatic site, if safe and feasible, prior to cycle 1~* After Cycle 3 of treatment, all patients who had a baseline biopsy will be required to undergo a mandatory biopsy of the same site if safe and feasible."