Conversion from accelerated approval was based on Phase III trial meeting ORR endpoint.
FDA gave Eisai the green-light on an efficacy sBLA covering the use of Ontak® in persistent or recurrent cutaneous T-cell lymphoma (CTCL) whose malignant cells express the CD25 component of the interleukin-2 (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.
Ontak was granted accelerated approval in February 1999 based on a surrogate endpoint, or an effect on a clinical endpoint other than survival. Full approval granted yesterday was based on a study that showed an overall response rate (ORR) of 46% for the 18 mcg/kg/day dose of Ontak and 37% for the 9 mcg/kg/day dose as compared to 15% for placebo.
Ontak is a genetically engineered cytotoxic fusion 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.