Background: Sonidegib (LDE225) is a potent, selective, and orally bioavailable inhibitor of smoothened receptor that demonstrated preclinical activity in combination with gemcitabine (GEM). Here, we present data from a phase 1b trial of sonidegib in combination with GEM in patients (pts) with pancreatic adenocarcinoma (PA). Methods: Pts with histologically or cytologically confirmed, locally advanced, or metastatic PA who had not been treated previously or had progressed despite prior chemotherapy (other than GEM) were included in the study. Dose escalation started with sonidegib 400 mg, once a day, in combination with GEM 1000 mg/m² IV infusion on days 1, 8, and 15 of a 28-day cycle. Results: A total of 18 pts were enrolled (9 pts each the in dose escalation and dose expansion phases). Pts discontinued the study because of disease progression (n = 11, 61.1%), consent withdrawal (n = 3, 16.7%), administrative problems (n = 3, 16.7%), and grade 3 or 4 blood creatine kinase (CK) elevation (n = 1, 5.6%). Three of 9 pts in dose escalation phase experienced dose-limiting toxicities during the first 8 weeks including grade 3 mucositis (n = 1), grade 3 CK elevation (n = 1), and grade 3 aspartate aminotransferase elevation (n = 1). Drug-related adverse events (AEs) of all grades were reported in 14 pts (77.8%) and grade 3 or 4 AEs were reported in 10 pts (55.6%). The most commonly reported AEs were anemia and nausea. No pharmacokinetic (PK) interaction was observed. Based on considerations of the statistical model, clinical assessment of safety, tolerability, PK, and pharmacodynamic results, maximum-tolerated dose and recommended dose were established as 400 mg of sonidegib in combination with the fixed standard dose of GEM (1000 mg/m²).The objective response rate was 11.1% and the median progression-free survival (PFS) was 4.9 months. Conclusions: The combination of sonidegib and GEM was generally well tolerated with moderate activity. Although no formal comparison can be made due to small sample size of this study, this combination provided a median PFS comparable to the current standard of care without conferring any additional clinical benefit. Clinical trial information: NCT01487785