Effect of daclizumab high-yield process in patients with highly active relapsing-remitting multiple sclerosis.

Patients with highly active relapsing-remitting multiple sclerosis (RRMS) are at greater risk for disease progression and may respond differently to MS therapeutics than those with less active disease. The current post hoc analysis evaluated the effects of daclizumab high-yield process (DAC HYP) vs. placebo in patients with highly active RRMS in the SELECT study. Highly active RRMS was defined as patients with ≥2 relapses in the year before randomization and ≥1 gadolinium-enhancing (Gd(+)) lesion at baseline. Because results were similar in the DAC HYP dose groups, data from the DAC HYP arms were pooled for analysis. Treatment with DAC HYP resulted in similar effects in highly active (n = 88) and less active (n = 506) RRMS patients. DAC HYP reduced the annualized relapse rate by 50 % and 51 % in the highly active (p = 0.0394) and less active (p < 0.0001) groups vs. placebo, respectively (interaction p = 0.82). DAC HYP reduced new/newly-enlarging T2 lesions (highly active RRMS 76 % reduction, p < 0.0001; less active RRMS 73 % reduction, p < 0.0001; interaction p = 0.18), the risk of having more Gd(+) lesions (highly active RRMS 89 % reduction, p < 0.0001; less active RRMS 86 % reduction, p < 0.0001; interaction p = 0.46), and sustained disability progression (highly active RRMS 88 % reduction, p = 0.0574; less active RRMS 46 % reduction, p = 0.0383; interaction p = 0.22) vs. placebo. DAC HYP efficacy was similar across the spectrum of MS disease activity as assessed prior to treatment initiation.