Background: Hepatocyte growth factor (HGF) and its receptor (c-Met) are activated in pancreatic ductal adenocarcinoma (PDAC). Preclinical data showed a combination of cabozantinib (cabo) and gemcitabine (gem) improved tumor control through inhibition of c-Met. We sought to determine the maximum tolerated dose (MTD) of cabo and gem in patients with advanced PDAC. Methods: Patients with unresectable or metastatic PDAC with ≤1 prior treatment and adequate organ function/performance status were eligible. Cabo was given orally once daily for 7 days and continued with gem infused IV over 30 min on days 1, 8, and 15 of a 28 day schedule. Doses were assigned in accordance with a Time to Event Continual Reassessment Method (TITE-CRM) per table below. Primary endpoint was MTD, defined as the highest dose level at which ≤25% of patients incurred a dose-limiting toxicity (DLT) in the first 35 days of therapy. Secondary endpoints included response rate, progression-free survival (PFS), and overall survival (OS). Results: Twelve patients were treated from July 2012 – May 2015. Median number of cycles given was 3 (range: 1-6). MTD was not determined. The probability of DLT was >25% for all dose levels attempted. Four of 10 evaluable patients experienced DLT (shown in table below), including grade 3 ALT/AST elevations (n=3) and thrombocytopenia (n=2). Five of 6 patients who continued therapy beyond cycle 2 incurred at least one grade 3 adverse event. Three patients had a partial response, but each discontinued therapy due to toxicity. Median PFS and OS were 4.7 (95% CI: 1.4 – 9.7) and 10.1 months (95% CI: 3.6 – 20.6), respectively, in treated patients. Conclusions: While the combination of cabo and gem demonstrated activity in PDAC, this regimen is impractical due to DLT at low doses and continuing toxicities despite dose reductions and schedule changes. Clinical trial information: NCT01663272

C, Cabo, dose in mg; G, Gem, dose in mg/m2; HPD, highest posterior density.