Background: In advanced pancreatic ductal adenocarcinoma (PDAC), first-line chemotherapy is the standard of care. Due to the absence of head-to-head comparisons in clinical trials, we performed this systematic review and network meta-analysis to compare treatment options for PDAC in terms of their efficacy and toxicity., Methods: PubMed, the Cochrane Central Register of Controlled Trials, Embase, and oncological meetings websites were searched until Nov 15, 2023. We included phase 2-3 randomised controlled trials published after Jan 1, 2000, evaluating first-line treatments in patients with previously untreated, unresectable, locally advanced or metastatic PDAC. Primary endpoints assessed were progression-free survival and overall survival. Summary data were extracted from published reports. The deviance information criterion was used to choose between a random-effects or fixed-effects model. Hazard ratios (HRs) with 95% credible intervals were estimated using a Bayesian approach. The risk of bias was evaluated using the Cochrane Risk of Bias 2 (RoB 2) tool and studies were graded as low, some concerns, or high risk of bias. The quality of evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation approach. This systematic review and network meta-analysis is registered with PROSPERO, CRD42023450330., Findings: 6050 records were screened and 79 randomised controlled trials (22 168 patients) were included in the analysis. Gemcitabine was the most frequent comparator (in 50 [63%] of 79 trials) and was considered as the reference treatment. A fixed-effect model was used to analyse the primary outcomes. Regarding progression-free survival (71 trials, 19 479 patients), the most effective treatments were gemcitabine plus nab-paclitaxel alternating folinic acid, fluorouracil, and oxaliplatin ([FOLFOX] HR 0·32, 95% credible interval 0·22-0·47), cisplatin, nab-paclitaxel, capecitabine, and gemcitabine ([PAXG] 0·35, 0·22-0·55), and liposomal irinotecan in combination with fluorouracil, leucovorin, and oxaliplatin ([NALIRIFOX] 0·43, 0·34-0·54), followed by fluorouracil, leucovorin, irinotecan, and oxaliplatin ([FOLFIRINOX] 0·55, 0·47-0·65) and gemcitabine plus nab-paclitaxel (0·62, 0·54-0·72). Similar results were observed for overall survival (79 trials, 22 104 patients): PAXG (HR 0·40, 95% credible interval 0·25-0·65), gemcitabine plus nab-paclitaxel alternating FOLFOX (0·46, 0·32-0·66), and NALIRIFOX (0·56, 0·45-0·70) had the highest benefit, followed by FOLFIRINOX (0·66, 0·56-0·78) and gemcitabine plus nab-paclitaxel (0·67, 0·59-0·77). The overall risk of bias was low to some concerns. Certainty of evidence was low., Interpretation: Our findings suggest that NALIRIFOX and FOLFIRINOX should be the preferred options for patients who can tolerate these regimens, with gemcitabine plus nab-paclitaxel remaining a viable alternative, particularly in patients unfit for triplet therapy. Phase 3 randomised controlled trials investigating concomitant or sequential quadruplets are warranted., Funding: None., Competing Interests: Declaration of interests CB reports travel and accommodation from Viatris. EB is supported by the Associazione Italiana per la Ricerca sul Cancro (AIRC) under Investigator Grant (IG20583), ouside the submitted work, institutional funds of Università Cattolica del Sacro Cuore (project D1) and funds from the Ministero della Salute (Ricerca Corrente 2022); reports speaker and travel fees from MSD, AstraZeneca, Pfizer, Eli-Lilly, BMS, Novartis, and Roche; and institutional research grants from AstraZeneca and Roche. GT reports funds from the Ministero della Salute (Ricerca Corrente 2022), the AIRC (Investigator Grant number IG26330), Ministero dell'Università e della Ricerca (PRIN 2022 PNRR Prot P2022LN3KS and PRIN 2022 Prot 2022P79F9N), and Agenzia Italiana del Farmaco, Ministero della Salute (J38D19000690001) FIMP, outside the submitted work; and consulting or advisory role for BMS, AstraZeneca, MSD, Merck, and Servier. LS is supported by the AIRC under My First Grant (MFAG27367), outside the submitted work, and reports consulting or advisory role for Pierre-Fabre, AstraZeneca, Bayer, SERVIER, Merck, Amgen, GSK, Incyte, Leopharma, MSD, and Takeda. All other authors declare no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.)