Preliminary results of the largest randomised, placebo-controlled clinical trial ever conducted in patients with cutaneous T-cell lymphoma (CTCL) showed that ONTAK was more than twice as effective as placebo in eliciting a clinical response in patients with CTCL.

The primary endpoint of this study was to measure the total percentage of documented responders based on improvement in tumour burden in skin, blood and lymph nodes in each treatment arm, confirmed over three consecutive cycles. Secondary endpoints included progression-free survival, which is defined as the time from the first day of treatment to the first observation of tumour progression or death due to any cause up to 30 days after the last dose of study drug. The results were presented at the annual meeting of the American Society of Clinical Oncology (ASCO).

ONTAK is indicated for the treatment of patients with persistent or recurrent cutaneous T-cell lymphoma (CTCL) whose malignant cells express the CD25 component of the IL-2 receptor. The safety and efficacy of denileukin diftitox in patients with CTCL whose malignant cells do not express the CD25 component of the IL-2 receptor have not been examined. ONTAK was granted accelerated approval in February 1999.

CTCL is a rare disease in which certain cells of the lymph system known as T lymphocytes become cancerous and affect the skin. CTCL can progress to the lymph nodes, spleen, liver and other organs. About 10 per cent of CTCL sufferers will experience progressive disease with lymph node and/or internal involvement with serious complications. There is no known cure for CTCL.

"The preliminary results of this study show that ONTAK achieved its primary endpoint, which was to prove superiority versus placebo in eliciting a clinical response in patients with CTCL," commented Miles Prince, MD, Chair of Cancer Services at Peter MacCallum Cancer Centre, Melbourne, Australia, and a lead investigator of this trial. "This study also showed an extension in progression-free survival for these patients, a secondary trial endpoint."

"We are pleased that research continues with ONTAK in the treatment of patients with CTCL," said Judy Jones, Executive Director of the Cutaneous Lymphoma Foundation. "This study reflects Eisai's ongoing commitment to satisfying unmet medical needs in oncology, particularly in CTCL, a form of cancer for which there is no cure."

ONTAK is a genetically engineered fusion toxin protein consisting of the amino acid sequences for the enzymatically-active portion of diphtheria toxin fused to the sequence of human interleukin-2, resulting in a molecule that is cytotoxic for cells bearing the target IL-2 receptor expressed on malignant cells.

ONTAK is indicated for the treatment of patients with persistent or recurrent cutaneous T-cell lymphoma (CTCL) whose malignant cells express the CD25 component of the IL-2 receptor. The safety and efficacy of denileukin diftitox in patients with CTCL whose malignant cells do not express the CD25 component of the IL-2 receptor have not been examined.