Spleen Irradiation With Nanoliposomal Irinotecan Plus 5-FU and Leucovorin in Metastatic Pancreatic Adenocarcinoma

Inclusion Criteria: * Arm A: * histologically or cytologically proved PDAC * metastatic PDAC * failed frontline gemcitabine-based chemotherapy and preparing for application of NHI-reimbursed nal-IRI/FL * splenomegaly: SV \> 270 ml (estimated) * lymphopenia: \< 1200/mm3 * no previous radiotherapy, local therapy (eg. radiofrequency ablation, irreversible electroporation, etc.), cell therapy (autologous or allogenic) used for pancreatic cancer * presence of at least one measurable lesion outside spleen * age between 20 and 75 years at registration * ECOG performance status of 0 or 1 * adequate major organ functions * Arm B: * limited progressive disease after prior nal-IRI/FL * prior treatment of nal-IRI/FL at least 4 doses * histologically or cytologically proven PDAC * metastatic PDAC before starting prior nal-IRI/FL * failed frontline gemcitabine-based chemotherapy before prior nal-IRI/FL * presence of at least one measurable lesion outside spleen * age between 20 and 75 years at registration * ECOG performance status of 0 or 1 or 2 after the chemotherapy phase * adequate major organ functions Exclusion Criteria: * interstitial lung disease * presence of diarrhea ≥ CTCAE v.5.0 grade 2 * concomitant systemic infection requiring treatment * clinically significant co-morbid medical conditions * prior organ allograft or allogeneic bone marrow transplantation * received systemic corticosteroids or immunosuppressants within 28 days before registration * known history of testing positive for human immunodeficiency virus (HIV) or known acquired immunodeficiency syndrome * moderate or severe ascites, pleural effusion, or pericardial effusion requiring treatment * central nervous system metastasis * prior or concurrent malignancies within the last 3 years, with the exception of carcinoma in situ of the cervix, or basal type skin cancer * any major surgery within 4 weeks of study treatment. Participants must have recovered from the effects of major surgery or significant traumatic injury. * pregnant women or nursing mothers, or positive pregnancy tests * severe mental disorder * spleen metastasis or direct invasion