PURPOSE SEQUOIA compared efficacy and safety of adding pegilodecakin (PEG), a pegylated recombinant human interleukin (IL)-10, with folinic acid, fluorouracil, and oxaliplatin (FOLFOX) in patients following progression on first-line gemcitabine-containing therapy with metastatic pancreatic ductal adenocarcinoma (PDAC). PATIENTS AND METHODS SEQUOIA, a randomized, global phase III study, compared FOLFOX with PEG + FOLFOX as second line in gemcitabine-refractory PDAC. Patients were randomly assigned 1:1 (PEG + FOLFOX:FOLFOX) and stratified by prior gemcitabine and region. Eligible patients had only one prior gemcitabine-containing treatment. Primary end point was overall survival (OS). Secondary end points included progression-free survival (PFS), response evaluation per Response Evaluation Criteria in Solid Tumor (RECIST) 1.1, and safety. Exploratory analyses included biomarkers related to immune activation. RESULTS Between March 1, 2017, and September 9, 2019, 567 patients were randomly assigned PEG + FOLFOX (n = 283) or FOLFOX (n = 284). Most (94.7%) patients received prior gemcitabine plus nab paclitaxel. OS was similar comparing PEG + FOLFOX versus FOLFOX (median: 5.8 v 6.3 months; hazard ratio = 1.045; 95% CI, 0.863 to 1.265). Also, PFS (median 2.1 v 2.1 months; hazard ratio = 0.981; 95% CI, 0.808 to 1.190) and objective response rate (4.6% v 5.6%) were similar between the treatment arms. Most common (≥ 35%) treatment-emergent adverse events in PEG + FOLFOX versus FOLFOX were thrombocytopenia (55% v 20%), anemia (40% v 16%), fatigue (61% v 45%), neutropenia (39% v 28%), abdominal pain (37% v 29%), nausea (45% v 41%), neuropathy (37% v 38%), and decreased appetite (35% v 31%). Exploratory analyses revealed increases in total IL-18, interferon (IFN)-γ, and granzyme B and decreases in transforming growth factor (TGF)-β with the addition of PEG. CONCLUSION PEG added to FOLFOX did not improve efficacy in advanced gemcitabine-refractory PDAC. Safety findings were consistent as previously observed from PEG with chemotherapy; toxicity was manageable and tolerable. Exploratory pharmacodynamic results were consistent with immunostimulatory signals of the IL-10R pathway.