Background: nal-IRI+5-FU/LV is approved in the United States and Taiwan for pts with mPDAC previously treated with gem-based therapy based on the NAPOLI-1 study which showed that nal-IRI+5-FU/LV improved overall survival (OS) vs 5-FU/LV (6.1 vs 4.2 mo; HR, 0.67; 95% CI, 0.49-0.92; P = 0.012; Wang-Gillam et al, Lancet. 2016). This post hoc analysis evaluated the efficacy and safety of nal-IRI+5-FU/LV in subgroups of pts defined by prior gem regimen including gem monotherapy and gem combinations (combo). Methods: This analysis (data cutoff, Nov 2015) focuses on the 236 pts assigned to nal-IRI+5-FU/LV q2w (n = 117) or 5-FU/LV qw for weeks 1-4 q6w cycle (n = 119). Pts previously received gem-based therapy in a neoadjuvant, adjuvant, locally advanced, or metastatic setting. Results: Of 117 pts in the nal-IRI+5-FU/LV arm, 53 (45%) previously received gem monotherapy and 64 (55%) previously received gem combo including erlotinib (n = 9) or nab-paclitaxel (n = 20). Of the 119 pts in the 5-FU/LV arm, 55 (46%) previously received gem monotherapy and 64 (54%) previously received gem combo including erlotinib (n = 17) or nab-paclitaxel (n = 11). Nal-IRI+5-FU/LV improved median OS, median PFS, and ORR vs 5-FU/LV, regardless of prior therapy (Table). Grade ≥3 treatment-emergent adverse events were not influenced by prior treatment. Clinical trial information: NCT01494506Conclusions: These resultsshow consistent benefit of nal-IRI+5-FU/LV treatment across subgroups of pts who previously received gem therapy and support the ASCO guidelines recommending nal-IRI+5-FU/LV for this pt population. These analyses may be limited by the small sample size of treatment arms.