Eisai Corporation of North America announced that the US Food and Drug Administration (FDA) has approved an efficacy supplemental biologics license application (sBLA) for Ontak (denileukin diftitox) solution for intravenous injection for the treatment of patients with persistent or recurrent cutaneous T-cell lymphoma (CTCL) whose malignant cells express the CD25 component of the interleukin (IL)-2 receptor (CD25+).

A separate efficacy supplement that included data from patients with CTCL whose malignant cells did not test positive for the CD25 component of the IL-2 receptor received a complete response letter.

The FDA's action, following a priority review, marks the conversion of an accelerated approval indication to full approval and is based on data from a phase-III clinical trial that evaluated the overall efficacy and safety of Ontak in certain patients with CTCL. CTCL is a term for a group of rare malignant lymphomas with primary manifestation in the skin. This trial was the largest phase-III, randomized, double-blind, placebo-controlled trial ever conducted in CTCL.

The study met its primary endpoint of overall response rate (ORR). ORR is the sum of complete and partial responses seen in a study, divided by the number of evaluable patients. The ORR was 46 per cent for the 18 mcg/kg/day dose of Ontak (p=0.002 vs. placebo) and 37 per cent for the 9 mcg/kg/day dose (p=0.03 vs. placebo) vs. 15 per cent for placebo. In addition, analysis of a secondary endpoint, progression-free survival (PFS), suggested a 73 per cent reduction in risk of disease progression in the 18 mcg/kg/day group (hazard ratio=0.27, p=0.0002, 95% CI 0.14, 0.54) and a 58% reduction in risk of disease progression in the 9 mcg/kg/day group (hazard ratio=0.42, p=0.02, 95% CI 0.20, 0.86) compared to placebo.

"These data confirm the benefit of the safety and efficacy profiles of Ontak. We are also encouraged that the data indicate a significant reduction in risk of disease progression compared to placebo," said Francine M Foss, Professor of Medicine, Assistant Director of Clinical Investigation, Hematologic Malignancies at Yale Cancer Center. "Physicians can have confidence in ONTAK since it is the most extensively studied agent in CTCL."

"The full approval of Ontak is in keeping with our human health care mission, to address the unmet medical needs of patients with CTCL," said Hajime Shimizu, chairman and CEO, Eisai Corporation of North America. "As an orphan drug indicated for a rare disease, Ontak has the potential to make a difference for this patient population." Ontak is indicated for the treatment of patients with persistent or recurrent cutaneous T-cell lymphoma whose malignant cells express the CD25 component of the IL-2 receptor.