Japan´s Eisai Co announced that U.S. health authorities have granted a full approval to the company´s sBLA application for marketing Ontak (denileukin diftitox), a solution given by intravenous injection treating patients with persistent or recurrent cutaneous T-cell lymphoma (CTCL), a group of rare malignant skin lymphomas.

The approval was based on data from a Phase III randomized, double-blind, placebo-controlled clinical trial that evaluated the overall efficacy and safety of Ontak in certain patients with CTCL, whose malignant cells express the CD25 component of the interleukin (IL)-2 receptor (CD25+).

The study met its primary endpoint of overall response rate (ORR), which is the sum of complete and partial responses seen in a study, divided by the number of evaluable patients. The ORR was 46 percent for the 18 mcg/kg/day dose of Ontak (p=0.002 vs. placebo) and 37 percent for the 9 mcg/kg/day dose (p=0.03 vs. placebo) vs. 15 percent for placebo.

The analysis of a secondary endpoint, progression-free survival (PFS), suggested a 73 percent reduction in risk of disease progression in the 18 mcg/kg/day group and a 58 percent reduction in risk of disease progression in the 9 mcg/kg/day group compared to placebo.

In this clinical trial, 25 percent of Ontak-treated patients (25/100) experienced a serious adverse event. The most common serious adverse events were capillary leak syndrome (4 percent), dehydration (4 percent), pyrexia (3 percent), hypotension (2 percent), skin disorder (2 percent), chest pain (2 percent), hypoalbuminemia (2 percent) and fatigue (2 percent).

The drug was discontinued in 20 patients (20 percent) due to one or more adverse events.

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.