Forodesine in the treatment of cutaneous T-cell lymphoma.

Cutaneous T-cell lymphoma (CTCL) is characterized by the accumulation of neoplastic CD4+ T lymphocytes in the skin. Given the lack of curative treatments for CTCL, there is a significant need for new, superior therapies. Forodesine is a transition-state analogue that inhibits purine nucleoside phosphorylase. Because it selectively targets T lymphocytes, it represents a drug of interest for the treatment of CTCL. Areas covered: Phase I/II dose-ranging studies of intravenous (IV) and oral forodesine demonstrated its activity, safety, and tolerability for refractory CTCL. Response rates were 31% and 27%, respectively. No dose-limiting toxicities were observed. These studies were followed by a phase II trial of oral forodesine 200 mg daily. This oral formulation showed only partial activity, with a response rate of 11%, likely attributable to underdosing. Common adverse events in these trials included infection, fatigue, peripheral edema, nausea, pruritus, headache, and insomnia. Expert opinion: IV and oral formulations of forodesine have demonstrated partial activity and an acceptable safety profile in patients with refractory CTCL. A higher oral dose, or sequential therapy consisting of IV forodesine followed by maintenance oral forodesine, may be more effective. With proper dosing, forodesine may emerge as a safe and effective treatment for refractory CTCL.