Background: GS-5745 is a monoclonal antibody inhibitor of matrix metalloproteinase 9 (MMP9), an extracellular enzyme involved in matrix remodeling, tumor growth, and metastasis. We present data from patients (pts) with advanced pancreatic adenocarcinoma enrolled in an ongoing multi-indication phase 1 study (NCT01803282) evaluating GS-5745. Methods: Following a monotherapy dose finding stage, pts with locally advanced or metastatic pancreatic cancer received gemcitabine (G) + nab-paclitaxel (Abraxane, A) and GS-5745 800 mg IV every 2 weeks. Treatment continued until disease progression, unacceptable toxicity or withdrawal of consent. Response was assessed every 8 weeks per RECIST version 1.1 criteria. Results: As of April 2016, 36 pts were enrolled (1 continues to receive GS-5745). The most frequently observed adverse events (AEs) of any grade include fatigue (75%), alopecia (55.6%), peripheral edema (55.6%) and nausea (50%). Grade ≥ 3 AEs observed in ≥ 10% of pts included neutropenia (25%), anemia (19.4%) and fatigue (13.9%). The median progression free survival (PFS) for all pts is 7.8 (90% confidence interval (CI) = [6.1, 11]) months (mos), median duration of response (DOR) is 5.8 mos and the objective response rate (ORR) is 44.4%. Of the 31 pts who were treatment naïve in the metastatic setting, median PFS is 9.2 (90% CI = [6.1, 11]) mos, median DOR 5.8 mos and the ORR 51.6%. Median baseline circulating MMP9 was 44.3 (range 12.4-549.6) ng/mL and 31 of 32 patients with post-baseline samples had undetectable MMP9 levels within 8 weeks. Conclusions: GS-5745+GA demonstrated numerically higher ORR and PFS compared to historical data without additional toxicity. Additionally, reductions in circulating MMP9 levels post treatment suggest target engagement by GS-5745 . These results suggest this combination may warrant additional study in first line metastatic pancreatic adenocarcinoma. Clinical trial information: NCT01803282