AbstractBackground: Pancreatic ductal adenocarcinoma (PDAC) is characterized by stromal fibrosis, hypoxia, and nutritional deprivation. Nutritional metabolic interventions may fundamentally change the tumor microenvironment and improve outcomes. A ketogenic diet (KD) (lower carbohydrate, moderate protein, higher fat) can significantly reduce glucose and insulin and stimulate ketogenesis. Triplet chemotherapy with gemcitabine/cisplatin/nab-paclitaxel has been associated with a median OS 16.4 months, PFS 10.1 months in patients with metastatic PDAC in the first-line setting. Recently, KD plus triplet chemotherapy was shown to inhibit murine pancreatic KPC tumor growth and prolong animal survival over chemotherapy alone (Yang et al, Med, 2022). Tumor growth inhibition was associated with glucose depletion, altered TCA substrate use and NADH elevation. Methods: In this Phase II trial, patients with treatment-naive metastatic PDAC were randomized to triplet chemotherapy with a medically supervised ketogenic diet (MSKD) or continuing their usual diet (non-MSKD). The MSKD is supported by Virta Health, who offers tracking of daily ketone (beta-hydroxybutyrate, BHB) and glucose levels, a web-based application, education, and communication with a remote care team to ensure sustained nutritional ketosis (BHB 0.5–3.0mM). Patients with BMI < 18, type 1 DM or history of DKA were excluded. Primary endpoint was PFS. Secondary endpoints: DCR (PR+CR+SD ≥ 9 weeks), change in CA 19-9 (CA125, CEA if not CA 19-9 expressers), average fasting insulin levels, HbA1c, body weight, gut microbiome, serum metabolites, QOL (QLQ- C30). Results: A total of 36 patients with untreated metastatic PDAC were enrolled. Among 32 evaluable patients (median age 65.9 years; 53% male), 16 were randomized to each arm. Both groups had similar baseline weight, HgbA1c, insulin and BHB levels (all p>0.05). Nine patients had type 2 DM; 6 required insulin. In the MSKD group, 15/16 achieved nutritional ketosis at any point during the study, with mean BHB of 0.57 mM (95% CI 0.40–0.73) and median proportion of days in ketosis of 39.4% (range 0-95.8%) by daily ketone tracking. Lab data showed significantly higher mean ± SD maximum change in BHB in the MSKD (0.5 ± 0.9 mmol/L) versus non-MSKD (–0.2 ± 0.3 mol/L) group (p = 0.018). There were no significant differences between groups in maximum change in weight, HbA1C, or insulin (all p > 0.05). The most common MSKD-related adverse events were Gr 1-2 fatigue (n=4), constipation (n=3), weight loss (n=3), and none stopped MSKD due to adverse events.Conclusion: A medically supervised ketogenic diet is feasible in patients with metastatic PDAC receiving triplet chemotherapy, with median proportion of days in ketosis of 39.4% and an acceptable safety profile. The MSKD is associated with comparable changes in insulin and HgbA1c levels compared to the non-MSKD diet, and sustained ketosis does not result in significantly greater weight loss. MSKD warrants further prospective exploration and analyses of the primary endpoint and correlative studies are ongoing.Citation Format: Gayle S Jameson, Erkut Borazanci, Diana L Hanna, Caroline GP Roberts, Meredith S Pelster, Richard C Frank, Angela T Alistar, Julia E Wiedmeier-Nutor, Sandra D Algaze, Brandon Fell, Sarah J Hallberg, Denise J Roe, Betsy C Wertheim, Derek Cridebring, Joshua D Rabinowitz, Stephen Gately, Daniel D Von Hoff, Drew W Rasco. Randomized phase II trial of two different nutritional approaches for patients receiving treatment for their advanced pancreatic cancer: initial results of safety and feasibility of the medically supervised ketogenic diet [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B012.