Phase I study of resminostat, an HDAC inhibitor, combined with S-1 in patients with pre-treated biliary tract or pancreatic cancer.

Resminostat is an oral hydroxamate inhibitor of class I, IIb, and IV histone deacetylases. S-1 is widely used to treat biliary tract cancer and pancreatic cancer in Japan. We performed a phase I study of resminostat combined with S-1 as second-line or later therapy in Japanese patients with biliary tract or pancreatic cancer. A total of 27 patients were enrolled. We determined the optimal regimen for resminostat/S-1 therapy in part 1, and investigated its safety and efficacy in part 2. In part 1, 17 patients were enrolled. One DLT (anorexia and stomatitis, respectively) occurred with each of regimens 2 and 3. In part 2, an additional 10 patients received regimen 3, which was selected in part 1. Regimen 3 was resminostat (200 mg/day on Days 1 to 5 and Days 8 to 12: 5 days on/2 days off) plus S-1 (80-120 mg/day according to body surface area on Days 1 to 14) repeated every 21 days. A total of 16 patients (13 with biliary tract cancer and 3 with pancreatic cancer) received regimen 3 and it was well tolerated. The most frequent treatment-related adverse events were thrombocytopenia and anorexia (11 patients each, 69%). The disease control rate was 81.3% (84.6% for biliary tract cancer and 66.7% for pancreatic cancer, respectively). Median progression-free survival was 3.1 months (5.5 and 2.3 months), while median overall survival was 8.8 months (10.2 and 4.7 months). In conclusion, regimen 3 was well tolerated by patients with pre-treated biliary tract or pancreatic cancer.

Phase I/II study of first-line combination therapy with sorafenib plus resminostat, an oral HDAC inhibitor, versus sorafenib monotherapy for advanced hepatocellular carcinoma in east Asian patients.

PURPOSE: Resminostat is an oral inhibitor of class I, IIB, and IV histone deacetylases. This phase I/II study compared the safety and efficacy of resminostat plus sorafenib versus sorafenib monotherapy as first-line therapy for advanced hepatocellular carcinoma (HCC). EXPERIMENTAL DESIGN: In phase I, resminostat (400 mg or 600 mg/day on days 1 to 5 every 14 days) was administered with sorafenib (800 mg/day for 14 days) to determine the recommended dose for phase II. In phase II, patients were randomized (1:1) to sorafenib monotherapy or resminostat plus sorafenib. The primary endpoint was time-to-progression (TTP). RESULTS: Nine patients (3: 400 mg, 6: 600 mg) were enrolled in phase I, and the recommended dose of resminostat was determined to be 400 mg/day. Then 170 patients were enrolled in phase II. Median TTP/overall survival (OS) were 2.8/14.1 months with monotherapy versus 2.8/11.8 months with combination therapy (Hazard Ratio [HR]: 0.984, p = 0.925/HR: 1.046, p = 0.824). The overall incidence of adverse events was similar in both groups (98.8% versus 100.0%). However, thrombocytopenia ≥ Grade 3 was significantly more frequent in the combination therapy group (34.5% versus 2.4%, p < 0.001). Subgroup analysis revealed that median TTP/OS was 1.5/6.9 months for monotherapy versus 2.8/13.1 months for combination therapy (HR: 0.795, p = 0.392/HR: 0.567, p = 0.065) among patients with a normal-to-high baseline platelet count (≥ 150 × 103/mm3). CONCLUSIONS: In patients with advanced HCC, first-line therapy with resminostat at the recommended dose plus sorafenib showed no significant efficacy advantage over sorafenib monotherapy.