It seems to be a reasonable approach to further study the use of daclizumab as an add-on therapy to interferon beta, but it will be important to know the full safety profile of daclizumab when used with other MS therapies. Progressive multifocal leukoencephalopathy has been associated with other monoclonal antibodies such as natalizumab (Tysabri) and rituximab (Rituxan), especially when used in combination with other immunomodulating or immunosuppressive agents.
Daclizumab did not seem to have a worrisome side effect profile, but some patients developed a skin rash, particularly those in the group that was given low-dose daclizumab.