A phase I trial of first-line
vorinostat, an orally bio-available
histone deacetylase inhibitor, in combination with
capecitabine plus
cisplatin (XP) was performed to assess recommend phase II trial dose in patients with advanced
gastric cancer. Five dose levels of three-weekly
vorinostat-XP were tested;
vorinostat was dosed at 300-400 mg once daily on Days 1-14,
capecitabine at 800-1,000 mg/m(2) twice daily on Days 1-14, and
cisplatin at 60-80 mg/m(2) on Day 1. To assess the pharmacodynamics of
vorinostat,
histone H3 acetylation was assessed in peripheral blood mononuclear cells before the study treatment and at Day 8 of cycle 1. In total, 30 patients with unresectable or metastatic gastric
adenocarcinoma were included. Dose-limiting toxicities were
thrombocytopenia,
fatigue,
stomatitis, and
anorexia. The following doses were recommended for phase II trial: 400 mg of
vorinostat once daily, 1,000 mg/m(2) of
capecitabine twice daily, and 60 mg/m(2) of
cisplatin. The most common grade 3-4 toxicities were
neutropenia (47 %),
anorexia (20 %),
thrombocytopenia (17 %), and
fatigue (13 %). In overall, response rate was 56 % (95 % confidence interval [CI]: 32-81). With a median follow-up of 14.1 months, the median progression-free survival and overall survival were 7.1 months (95 % CI: 3.8-10.3) and 18.0 months (95 % CI: 4.8-31.1), respectively. The change in H3 acetylation
after treatment with
vorinostat correlated significantly with the
vorinostat dose (300 vs. 400 mg/day) and the baseline level of H3 acetylation before treatment. Three-weekly
vorinostat-XP regimen is feasible and recommended for further development in advanced
gastric cancer.