Vorinostat (Suberoylanilide Hydroxamic Acid, SAHA) Provides Prolonged Clinical Benefit to Advanced Cutaneous T-Cell Lymphoma Patients: Updated Results of the Phase IIb Multicenter Clinical Trial.

Purpose: To evaluate the activity and safety of the histone deacetylase inhibitor vorinostat in advanced cutaneous T-cell lymphoma (CTCL) patients (pts).

Patients and Methods: Advanced CTCL pts received oral vorinostat 400 mg daily until disease progression (PD) or intolerable toxicity in this open label Phase IIb trial. Eligible pts must have received ≥ 2 prior systemic therapies which included bexarotene unless intolerable. The planned sample size was ≥ 50 evaluable pts with stage ≥ IIB. The primary endpoint was the objective response rate (ORR) as measured by a modified skin severity weighted assessment tool (SWAT). The study would be positive if the ORR in ≥ stage IIB pts was ≥ 20%. Time to response, time to progression (TTP), response duration (DOR, from time of first response), pruritus relief, safety and gene expression changes were also evaluated.

Results: Seventy-four pts (median age, 60 y [range, 39–83]; median 3 prior systemic therapies) were enrolled (61 pts ≥ stage IIB) at 18 centers. Data cut-off was 5/06 with a median follow-up of 10 m. Efficacy data are shown (Table 1). The ORR was 29.5% in ≥ stage IIB pts. The median DOR and TTP were not reached but estimated to be at least 6.1 m and 9.8 m, respectively, for ≥ stage IIB responders. Median TTP was 4.9 m for all pts. Overall, 32% of pts had pruritus relief. The most common drug-related adverse experiences (AE) were diarrhea (49%), fatigue (46%), nausea (43%) and anorexia (26%), and were mostly ≤ grade 2. Seven pts discontinued and 10 had dose modification due to drug-related AE. Drug-related AE ≥ grade 3 included fatigue (5%), pulmonary embolism (5%), thrombocytopenia (5%) and nausea (4%). Fifteen pts, including 9 responders, were receiving treatment as of 11/05. Three of these pts discontinued due to PD (n = 2) or unacceptable toxicity (n = 1), and 12 have received vorinostat for > 1 y. A pharmacodynamic signature of vorinostat exposure based on gene expression changes was detected.

Conclusion: These updated results with additional follow-up continue to demonstrate that oral vorinostat remains effective in advanced CTCL with an acceptable safety profile.