Phase 1b study of galunisertib in combination with gemcitabine in Japanese patients with metastatic or locally advanced pancreatic cancer

Purpose: Transforming growth factor-beta inhibitors may enhance the antitumor activity of gemcitabine with acceptable safety and tolerability. This open-label, multicenter, non-randomized phase 1b study assessed the safety/tolerability, pharmacokinetics, and tumor response of galunisertib plus gemcitabine in Japanese patients with advanced or metastatic pancreatic cancer. Methods: During each 28-day cycle, galunisertib 150 mg was administered orally twice daily (300 mg/day) for 14 days, followed by 14 days of rest. Gemcitabine 1000 mg/m² was intravenously given on Days 8, 15, and 22. Safety was assessed by the incidence of dose-limiting toxicities (DLTs) in the first cycle and treatment-emergent adverse events (TEAEs). Efficacy was assessed by antitumor activity and changes in carbohydrate antigen 19-9 (CA19-9). Results: No DLTs were reported. All 7 enrolled patients had ≥1 TEAE, of which the most common included anorexia, decreased neutrophil count, and decreased white blood cell count. Grade ≥3 TEAEs were observed in 6 patients; 4 patients had Grade ≥3 TEAEs (decreased neutrophil, white blood cell, and lymphocyte count; hypophosphatemia) considered possibly related to study drug(s). The pharmacokinetic profile of galunisertib in combination with gemcitabine was similar to that previously observed for galunisertib alone. The clinical response [complete response (CR), partial response (PR), or stable disease] rate was 42.9%, and the median progression-free survival was 64 days; no CR/PR were achieved. Conclusion: Galunisertib plus gemcitabine had an acceptable safety/tolerability profile with evidence of efficacy in Japanese patients with advanced or metastatic pancreatic cancer.