Trends in the treatment of cutaneous T-cell lymphoma – critical evaluation and perspectives on vorinostat

Abstract

Epigenetic modification with small molecule histone deacetylase inhibitors has been a promising new anti-neoplastic approach for various solid and hematological malignancies, particularly cutaneous T-cell lymphoma (CTCL). Oral vorinostat was the first histone deacetylase inhibitor approved to enter the clinical oncology market for treating CTCL patients who have progressive, persistent, or recurrent disease after failing two systemic therapies. In two phase II clinical trials, oral vorinostat was found to be safe and effective at a dose of 400 mg/day, with an overall response rate of 24%-30% in heavily pretreated patients with advanced CTCL, including those with large-cell transformed mycosis fungoides and Sezary syndrome. About half of CTCL patients receiving vorinostat also experienced substantial relief in pruritus and thus a marked improvement in quality of life. A subsequent follow-up study reported long-term safety and clinical benefits of vorinostat in patients with refractory CTCL, regardless of previous treat- ment failures. The most frequent side effects of vorinostat include gastrointestinal symptoms, fatigue, and thrombocytopenia. These adverse reactions are dose-related and reversible upon cessation of therapy. Preclinical studies have supported the therapeutic potential of vorinostat by demonstrating in vitro and in vivo anti-tumor activities against CTCL, including selective induction of apoptosis in malignant T cells, inhibition of angiogenesis, suppression of signal transducer and activator of transcription proteins, and up-regulation of pro-apoptotic proteins. Identification of biomarkers of response and resistance will help select CTCL patients most likely to benefit from treatment and guide the design of effective combination therapies.