A phase 1b study of transforming growth factor-beta receptor I inhibitor galunisertib in combination with sorafenib in Japanese patients with unresectable hepatocellular carcinoma

Background Galunisertib inhibits type I transforming growth factor-beta receptor serine/threonine kinase. The primary objective of this study was to evaluate the safety and tolerability of galunisertib in combination with sorafenib in Japanese patients with unresectable hepatocellular carcinoma. Patients and methods This open-label, dose-escalation, multicenter, nonrandomized phase 1b study consisted of two dose levels of galunisertib, 160 or 300 mg/day, in combination with sorafenib 800 mg/day. Galunisertib 80 mg or 150 mg was administered orally twice daily for 14 days followed by 14 days of rest plus sorafenib 400 mg administered orally twice daily for 28 days. The dose-limiting toxicity evaluation was 28 days after the first dose. Safety measures, pharmacokinetics, and antitumor activity were assessed. Results Fourteen patients, 7 at each galunisertib dose, were enrolled and treated. Three dose-limiting toxicities were reported for 2 patients. The most common treatment-emergent adverse events (TEAEs) were hypophosphatemia (14 patients [100%]), palmar-plantar erythrodysesthesia syndrome (12 patients [85.7%]), and decreased platelet count (10 patients [71.4%]). The most common grade ≥ 3 TEAEs were hypophosphatemia (10 patients [71.4%]) and palmar-plantar erythrodysesthesia syndrome (7 patients [50.0%]). No grade 5 TEAEs were reported. The pharmacokinetic profile of galunisertib in combination with sorafenib was similar to that previously reported for galunisertib. Eleven patients had a best overall response of stable disease, and 1 patient achieved a partial response by hepatocellular carcinoma-specific modified RECIST. Conclusions These data are consistent with the known safety profile for galunisertib and sorafenib and confirm tolerability of the recommended dose of galunisertib (150 mg twice daily for 14 days) in combination with sorafenib in Japanese patients with unresectable hepatocellular carcinoma.