BackgroundIn metastatic pancreatic ductal adenocarcinoma (mPDAC), first line treatment options usually include combination regimens of folinic acid, 5-fluorouracil (5-FU), irinotecan, and oxaliplatin (FOLFIRINOX or mFOLFIRINOX) or gemcitabine based regimens such as in combination with albumin-bound paclitaxel (GEM + nab-PTX). After progression, multiple regimens including NALIRI + 5-FU and folinic acid, FOLFIRINOX, 5-FU-based oxaliplatin doublets (OFF, FOLFOX, or XELOX), or 5-FU-based monotherapy (FL, capecitabine, or S-1) are considered appropriate by major guidelines. This network meta-analysis (NMA) aimed to compare the efficacy of different treatment strategies tested as second-line regimens for patients with mPDAC after first-line gemcitabine-based systemic treatment.MethodsRandomized phase II and III clinical trials (RCTs) were included if they were published or presented in English. Trials of interest compared two active systemic treatments as second-line regimens until disease progression or unacceptable toxicity. We performed a Bayesian NMA with published hazard ratios (HRs) and 95%confidence intervals (CIs) to evaluate the comparative effectiveness of different second-line therapies for mPDAC. The main outcomes of interest were overall survival (OS) and progression free survival (PFS), secondary endpoints were grade 3–4 toxicities. We calculated the relative ranking of agents for each outcome as their surface under the cumulative ranking (SUCRA). A higher SUCRA score meant a higher ranking for efficacy outcomes.ResultsA NMA of 9 treatments was performed for OS (n = 2521 patients enrolled). Compared with 5-FU + folinic acid both irinotecan or NALIRI + fluoropyrimidines had a trend to better OS (HR = 0.76, 95%CI 0.21–2.75 and HR = 0.74, 95%CI 0.31–1.85). Fluoropyrimidines + folinic acid + oxaliplatin were no better than the combination without oxaliplatin. The analysis of treatment ranking showed that the combination of NALIRI + 5-FU + folinic acid was most likely to yield the highest OS results (SUCRA = 0.7). Furthermore, the NMA results indicated that with the highest SUCRA score (SUCRA = 0.91), NALIRI + 5-FU + folinic acid may be the optimal choice for improved PFS amongst all regimens studied.ConclusionsAccording to the NMA results, NALIRI + 5-FU, and folinic acid may represent the best second-line treatment for improved survival outcomes in mPDAC. Further evidence from prospective trials is needed to determine the best treatment option for this group of patients.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12876-023-02853-w.