Zenapax (daclizumab)

Parent companies: Biogen Idec and PDL BioPharma

• Administered via intravenous infusion every four weeks; also studied in subcutaneous injections.


• Zenapax is a genetically engineered antibody against a substance necessary for the growth of T cells. It results in a sustained but reversible reduction in activated T cells, and reduces inflammation.


• A study in RRMS and SPMS patients (who continued to experience worsening disease activity with interferon-beta therapy) showed the drug was well tolerated. The study also reported to improve or stabilize 60 percent of patients and reduced the number of active lesions.


• The ongoing CHOICE Phase II trial adds Zenapax to interferons in 30 patients with active MS; the treated group experienced a significant reduction in new or enlarged enhancing lesions. A recent study used the drug alone in those participants in the CHOICE study who had developed neutralizing antibodies to interferon-beta. The results suggest that the effect of Zenapax is not dependent on the presence of functioning interferon-beta, indicating that it may have potential as an independent therapy.


• An ongoing study of RRMS will determine the effect of three different doses of Zenapax on brain-lesion activity as measured by MRI. An extension study is also underway that will focus on safety and tolerability.