Background: First-line treatment of metastatic pancreatic ductal adenocarcinoma (PDAC) includes nab-paclitaxel/gemcitabine. Ibrutinib, a Bruton's tyrosine kinase inhibitor, exhibits antitumor activity through tumor microenvironment modulation. The safety and efficacy of first-line ibrutinib plus nab-paclitaxel/gemcitabine treatment in patients with PDAC were evaluated., Patients and Methods: RESOLVE (NCT02436668) was a phase III, randomized, double-blind, placebo-controlled study. Patients (histologically-confirmed PDAC; stage IV diagnosis ≥6 weeks of randomization; Karnofsky performance score ≥70) were randomized to once-daily oral ibrutinib (560 mg) or placebo plus nab-paclitaxel (125 mg/m 2 ) and gemcitabine (1000 mg/m 2 ). Primary endpoints were overall survival (OS) and investigator-assessed progression-free survival (PFS); overall response rate and safety were assessed., Results: In total, 424 patients were randomized (ibrutinib arm, n = 211; placebo arm, n = 213). Baseline characteristics were balanced across arms. After a median follow-up of 25 months, there was no significant difference in OS between ibrutinib plus nab-paclitaxel/gemcitabine versus placebo plus nab-paclitaxel/gemcitabine (median of 9.7 versus 10.8 months; P = 0.3225). PFS was shorter for ibrutinib plus nab-paclitaxel/gemcitabine compared with placebo plus nab-paclitaxel/gemcitabine (median 5.3 versus 6.0 months; P < 0.0001). Overall response rates were 29% and 42%, respectively (P = 0.0058). Patients in the ibrutinib arm had less time on treatment and received lower cumulative doses for all agents compared with the placebo arm. The most common grade ≥3 adverse events for ibrutinib versus placebo arms included neutropenia (24% versus 35%), peripheral sensory neuropathy (17% versus 8%), and anemia (16% versus 17%). Primary reasons for any treatment discontinuation were disease progression and adverse events., Conclusions: Ibrutinib plus nab-paclitaxel/gemcitabine did not improve OS or PFS for patients with PDAC. Safety was consistent with known profiles for these agents., Competing Interests: Disclosure MT: consultancy/advisory role with Advance Medical, AstraZeneca, Bristol-Myers Squibb (BMS), EcoR1 Capital, Elicio Therapeutics, FibroGen, Inc., GlaxoSmithKline, Immunovia, ISPEN, Karyopharm Therapeutics, Merck & Co., Inc., and Swedish Orphan Biovitrum; research funding from Celgene and Halozyme; other relationship(s) with Astellas Pharma Global Development, Inc. (DSMC). D-YO: consultancy/advisory role with ASLAN, AstraZeneca, Bayer, Genentech/Roche, Halozyme, Merck Serono, Novartis, Taiho, and Zymeworks; research funding from Array, AstraZeneca, and Eli Lilly. JT: consultancy/advisory role with Array Biopharma, AstraZeneca, Bayer, BeiGene, Biocartis, Boehringer Ingelheim, Chugai, F. Hoffmann-La Roche Ltd, Foundation Medicine, Genentech, Inc., Genmab A/S, HalioDX SAS, Halozyme, Imugene Limited, Inflection Biosciences Limited, Ipsen, Kura Oncology, Lilly, Merck Sharp & Dohme (MSD), Menarini, Merck Serono, Merrimack, Merus, Molecular Partners, Novartis, Peptomyc, Pfizer, Pharmacyclics LLC, an AbbVie Company, ProteoDesign SL, Rafael Pharmaceuticals, Roche Diagnostics, Sanofi, Seagen, Seattle Genetics, Servier, Symphogen, Taiho, and VCN Biosciences. MR: honoraria from Baxalta, Celgene, and Shire; consultancy/advisory role with Baxalta, Celgene, Eli Lilly, Novartis, Novocure, Pfizer, and Shire; research funding to Institution from Celgene; travel expenses from Celgene, AstraZeneca; other relationship(s) with AstraZeneca, Boston Pharmaceuticals, and Celgene. EVC: consultancy/advisory role with AstraZeneca, Bayer, BMS, Celgene, Lilly, MSD, Merck DGaA, Novartis, Roche, and Servier; research funding from Amgen, Bayer, Boehringer Ingelheim, BMS, Celgene, Ipsen, Lilly, Merck, Merck KGaA, Novartis, Roche, and Servier. AH: consultancy/advisory role with AbbVie, Ipsen, Merck, and Novartis; research funding from Ipsen. D-TW: speakers' bureau for AstraZeneca, BMS, Celgene, Eisai, Falk, Ipsen, Novartis, Roche, Servier, Shire Baxalta, and Sirtex; travel expenses from Bayer Health Pharma, Celgene, Ipsen, Novartis, and Sirtex. NS: honoraria from Eli Lilly, Merck Serono, MSD Oncology, and Pierre Fabre; consultancy/advisory role with AstraZeneca, Pfizer, and Servier; research funding from AstraZeneca, BMS, and Pfizer; travel expenses from AstraZeneca, BMS, Eli Lilly, Merck, and Roche. J-BB: honoraria from Amgen, AstraZeneca, Bayer, Celgene, Merck Serono, Mundipharma, Pierre Fabre, Roche, Sanofi, and Servier; consultancy/advisory role with Amgen, AstraZeneca, Bayer, Merck Serono, Pierre Fabre, and Servier; travel expenses from Amgen, Bayer, Celgene, Merck Serono, Roche, Sanofi, and Servier. H-MC: research funding from Astellas, Halozyme, Pharmacyclics LLC, an AbbVie Company, Senhwa Biosciences, Taiho Oncology. JM: consultancy/advisory role with Advance Medical, AstraZeneca, Bayer, Pierre-Fabre, Roche, Sanofi, Servier, Shire, and Sirtex; research funding from Amgen, Biocartis, Incyte, Merck, Nanostring, and Servier; patents, royalties, or other intellectual property with GAIS-42-patent P5020EP00. RG: honoraria from AAA, Amgen, Bayer, BMS, Ipsen, Lilly, Merck, MSD, Novartis, PharmaMar, Pfizer, Roche, and Sanofi; research funding from ARMO Biosciences, AstraZeneca, Pfizer, Novartis, Ipsen, Roche, Pharmacyclics LLC, an AbbVie Company, Boston Biomedicals, Merck, MSD, Amgen, Sanofi, Bayer, BMS, Boehringer, Sysmex, Gilead Sciences, Servier, Adacap, VCN, Lilly, PharmaMar; travel expenses from Ipsen, Merck, Novartis, and Servier. SL: consultancy/advisory role with Amgen, Lilly, Merck Serono, and Servier; research funding from Amgen and Merck Serono; speakers' bureau for BMS, Lilly, Merck Serono, Roche, and Servier. LMC: employment with Oregon Health & Science University; honoraria from Aduro Biotech, AstraZeneca, Carisma Therapeutics, Inc., Cell Signaling Technologies, CytomX Therapeutics, Inc., Jackson Laboratories, Seattle Genetics, Syndax Pharmaceuticals, Inc., Verseau Therapeutics, Inc., and Zymeworks, Inc.; consultancy/advisory role with Carisma Therapeutics Inc., Cell Signaling Technologies, CytomX Therapeutics, Inc., Syndax Pharmaceuticals, Inc., Verseau Therapeutics, Inc., and Zymeworks, Inc.; research funding (for profit) Acerta Pharma, Deciphera Pharmaceuticals, Innate Pharma, Roche Glycart and Parker Institute for Immunotherapy, and Syndax Pharmaceuticals, Inc.; patents, royalties, or other intellectual property with Oregon Health & Science University; other relationship(s) with Reagent from Reagent support from: Acerta Pharma, LLC, Cell Signaling Technologies, Deciphera Pharmaceuticals, Genentech/Roche Glycart AG, NanoString Technologies, Inc., Plexxikon, Inc, and Syndax Pharmaceuticals. LF: research funding from AbbVie, Bavarian Nordic, BMS, Dendreon, Janssen, Merck, Roche/Genentech. GC: employment with Pharmacyclics LLC, an AbbVie Company; stock ownership in AbbVie. DJ: employment with Pharmacyclics LLC, an AbbVie Company; leadership role with Pharmacyclics LLC, an AbbVie Company; stock ownership in AbbVie; patents, royalties, or other intellectual property with Pharmacyclics LLC, an AbbVie Company. TM: consultancy/advisory role with Advance Medical HCMS, Baxter, BioLineRX Ltd, Celgene SLU, Eisai, Genzyme, Incyte, IPSEN Pharma Lab. Menarini, Lab. Servier, Lilly, QED Therapeutics, MSD, Prime Oncology EU, QED Therapeutics Inc., Sanofi-Aventis; research funding from Agios, ASLAN, AstraZeneca, Bayer, Celgene, Genentech, Hallozyme, Immunomedics, Lilly, Merimarck, Millenium, Novartis, Pfizer, Pharmacyclics LLC, an AbbVie Company, and Roche; travel expenses from Servier and Incyte. LCT has declared no conflicts of interest., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)