Background: The multi-kinase inhibitor sorafenib (S) and HDAC inhibitor vorinostat (V) demonstrated synergism against preclinincal pancreatic cancer (PaCa) models. The combination of S & V also potently radiosensitized pancreatic cancer cells and enhanced the activity of gemcitabine (G). This led to a phase 1 trial to determine the doses and schedule appropriate for phase 2 study of S & V with weekly G and intensity modulated radiotherapy (IMRT) as neoadjuvant treatment of PaCa following chemotherapy. Methods: Using a 3+3 dose-escalation design, adult patients with resectable, borderline resectable, unresectable, and lymph node positive PaCa were enrolled to 6 dose levels. Enrolled patients had completed at least 8w of neoadjuvant chemotherapy prior to IMRT. The schedule of administration was weekly 200mg/m2 G weekly during IMRT, S & V were dosed either 3x or 5x weekly during IMRT. Primary endpoint was to identify the dose and schedule for S & V with G based chemoradiation. Key secondary endpoints included antitumor activity, R0 resection rate, OS. Correlative studies to evaluate a variety of biomarkers and Nanostring expression analysis on pre- and post-therapy tumor specimens were also performed. Results: 22 patients were enrolled and 21 treated at 6 dose levels. Due to thrombocytopenia limiting drug exposure, the trial was modified to reduce G to 200mg/m2/wk and S & V to 3 d/wk instead of 5 d/wk. 13 patients were eligible for surgery, and 9 had R0 resections. Conclusions: Our findings indicate that the study regimen was well tolerated, typical toxicities of S (hand foot syndrome) were not observed with intermittent dosing. Uncomplicated cytopenias limited drug exposure, which was improved with intermittent S&V dosing. The RP2D of the combination is S (400mg po BID 3d/wk), V (200mg po qd 3d/wk), G 200mg/m² IV weekly, with IMRT (50.4 Gy over 28 fractions, 5d/wk). Antitumor activity was observed across dose levels, with an encouraging R0 resection rate. These results warrant further investigation of combining S and V with G and IMRT as neoadjuvant treatment of PaCa following chemotherapy. Analyses of correlative studies and OS are underway. Clinical trial information: NCT02349867