United States of America. The Food and Drug Administration has approved denileukin diftitox (Ontak: Seragen), a new biological treatment for cutaneous t-cell lymphoma (CTCL), a rare slow-growing form of non-Hodgkin’s lymphoma, for use in patients with advanced or recurrent CTCL when other treatments have failed.

Known as a “fusion protein”, denileukin diftitox is produced by genetically fusing protein from the diphtheria toxin to interleukin-2 (IL-2), a naturally occurring immune system protein. This stable fusion protein targets cells with receptors for IL-2 on their surfaces, including malignant cells and some normal lymphocytes, resulting in cell death.

Because denileukin diftitox also affects normal lymphocytes, which are infection- fighting cells, and because patients with CTCL are prone to infections, patients should be monitored carefully during treatment. Severe infections were reported in 23% of patients in the trial, although it is unclear whether denileukin diftitox was the cause. Other adverse effects related to the intravenous infusion of denileukin diftitox included allergic reactions, flu-like symptoms and fluid retention that may lead to other complications.

Reference: FDA Talk Paper T99-8 dated 5 February 1999.