Results that led to larger-scale clinical trials of daclizumab high-yield process (DAC HYP, Biogen Idec and Abbott Pharmaceuticals) have been published. The phase II SELECT trial found that this monoclonal antibody, taken by injection under the skin every four weeks, significantly reduced the average annual relapse rate and the risk of progression in a study of over 600 people with relapsing-remitting MS
over a one-year trial. Larger and longer phase III studies currently underway should provide additional information regarding daclizumab’s effectiveness and safety. Dr. Ralf Gold (Ruhr-University Bochum, Germany) and an international team of investigators authored the paper, published in The Lancet
online on April 4, 2013.
Daclizumab high yield process is a monoclonal antibody, taken by injection under the skin every four weeks. It targets a receptor (docking site) that helps a key immune signaling chemical, called interleukin-2, to activate immune T cells thought to be involved in MS attacks. DAC HYP is a highly concentrated liquid formulation of daclizumab.
Over six hundred people with relapsing-remitting MS were randomly assigned to receive DAC HYP 150 mg, DAC HYP 300 mg or inactive placebo every four weeks for 52 weeks. The primary endpoint studied was the average annual relapse rate over one year. Additional outcomes evaluated included disease activity observed on MRI, the proportion of people who experienced relapses, disability progression (as measured by changes in the EDSS disease activity scale lasting at least 12 weeks), brain atrophy (shrinkage), safety and tolerability, and some self-reported measures of health.
After one year, both doses of DAC HYP significantly reduced the average annual relapse rate by 50 to 54% compared with placebo. More were relapse-free in the treatment groups than in the placebo group, and the therapy decreased new or enlarging MRI brain lesions. Change in disease progression occurred in 6% of those on the 150mg dose, 8% of those on the 300mg dose, and 13% of those on placebo, which represents a relative reduction of disease progression by up to 57% over placebo. Changes in whole brain atrophy did not differ significantly between the treatment and placebo groups at one year. Self-reported health measures favored the 150mg dose group over placebo, but not the 300mg dose group.
Daclizumab was generally well tolerated during the study. There were increased numbers of serious infections, serious skin events, and increased risk of higher elevations of liver enzymes (a marker of liver damage) experienced by those in the DAC HYP groups. One death occurred, involving a complication during recovery from a serious skin-related adverse event. The authors note that investigators in ongoing trials have implemented changes in patient monitoring with a goal of identifying and treating potential adverse events as soon as possible.
DAC HYP showed significant benefit on several measures including relapses, risk of disability progression, and new disease activity seen on MRI. Overall safety was generally good, however some concerns regarding liver enzyme elevations appeared relatively late in the study period, and infection rates and skin reactions to the injections were higher in those treated with daclizumab. Larger and longer phase III trials currently underway should provide additional information regarding daclizumab’s effectiveness and safety.