Phase I study of an oral histone deacetylase inhibitor, suberoylanilide hydroxamic acid, in patients with advanced cancer.

PURPOSE: To determine the safety, dosing schedules, pharmacokinetic profile, and biologic effect of orally administered histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) in patients with advanced cancer. PATIENTS AND METHODS: Patients with solid and hematologic malignancies were treated with oral SAHA administered once or twice a day on a continuous basis or twice daily for 3 consecutive days per week. Pharmacokinetic profile and bioavailibity of oral SAHA were determined. Western blots and enzyme-linked immunosorbent assays of histones isolated from peripheral-blood mononuclear cells (PBMNCs) pre and post-therapy were performed to evaluate target inhibition. RESULTS: Seventy-three patients were treated with oral SAHA and major dose-limiting toxicities were anorexia, dehydration, diarrhea, and fatigue. The maximum tolerated dose was 400 mg qd and 200 mg bid for continuous daily dosing and 300 mg bid for 3 consecutive days per week dosing. Oral SAHA had linear pharmacokinetics from 200 to 600 mg, with an apparent half-life ranging from 91 to 127 minutes and 43% oral bioavailability. Histones isolated from PBMNCs showed consistent accumulation of acetylated histones post-therapy, and enzyme-linked immunosorbent assay demonstrated a trend towards a dose-dependent accumulation of acetylated histones from 200 to 600 mg of oral SAHA. There was one complete response, three partial responses, two unconfirmed partial responses, and 22 (30%) patients remained on study for 4 to 37+ months. CONCLUSIONS: Oral SAHA has linear pharmacokinetics and good bioavailability, inhibits histone deacetylase activity in PBMNCs, can be safely administered chronically, and has a broad range of antitumor activity.

Fluorodeoxyglucose positron emission tomography as an outcome measure for castrate metastatic prostate cancer treated with antimicrotubule chemotherapy.

PURPOSE: Standard imaging studies are limited as outcome measures for patients with metastatic prostate cancer. We tested the hypothesis that serial fluorodeoxyglucose positron emission tomography (FDG-PET) scans can serve as an outcome measure for patients with castrate metastatic prostate cancer treated with antimicrotubule chemotherapy. EXPERIMENTAL DESIGN: FDG-PET scans were done at baseline, 4, and 12 weeks of treatment. The average maximum standardized uptake value (SUVmaxavg) was measured in up to five lesions and was tested as the quantitative outcome measure. Prostate-specific antigen (PSA) at 4 weeks and PSA, bone scan, and soft tissue imaging at 12 weeks were considered standard outcome measures. The change in SUVmaxavg that distinguished clinically assessed progression from nonprogression was sought. RESULTS: Twenty-two PET scans were reviewed and compared with PSA at 4 weeks; 18 PETs were compared at 12 weeks with standard outcome measures. Applying the PSA Working Group Consensus Criteria guideline that a 25% PSA increase constitutes progression to the SUVmaxavg, PET correctly identified the clinical status of 20 of 22 patients (91%) at 4 weeks and 17 of 18 patients at 12 weeks (94%). The accuracy of PET could be further optimized if a >33% increase in PSA and SUVmaxavg were used to define progression. CONCLUSION: FDG-PET is promising as an outcome measure in prostate cancer. As a single modality, it can show treatment effects that are usually described by a combination of PSA, bone scintigraphy, and soft tissue imaging. Preliminarily, a >33% increase in SUVmaxavg or the appearance of a new lesion optimally dichotomizes patients as progressors or nonprogressors.