NEW ORLEANS – The greatest effect of the investigational, B-cell–targeting humanized monoclonal antibody ocrelizumab in treating primary progressive multiple sclerosis (PPMS) may be in patients with T1 gadolinium-positive (Gd+) lesions at baseline, which are indicative of an ongoing or recent MS relapse, according to a subgroup analysis of the randomized, double-blind, placebo-controlled ORATORIO trial.
The analysis hinted at the possibility that ocrelizumab may reduce the risk of confirmed disability progression (CDP) at 12 weeks or 24 weeks to a slightly higher degree among PPMS patients with T1 Gd+ lesions than in those without such lesions, although the differences did not reach statistical significance. The findings await further study because ORATORIO was not powered to demonstrate efficacy differences between the subgroups, Dr. Jerry Wolinsky of the University of Texas Health Science Center at Houston noted in a presentation at the meeting held by the Americas Committee for Treatment and Research in Multiple Sclerosis.
In ORATORIO, ocrelizumab (600 mg intravenous infused every 6 months as two 300-mg infusions given 2 weeks apart) was compared with placebo in 732 people with PPMS in a 120-week blinded treatment. The number of patients with T1 Gd+ lesions at baseline was similar in the placebo arm (60/244, 24.7%) and the ocrelizumab arm (133/488, 27.5%). T1 Gd-negative (Gd-) lesions, which are likely older and indicative of the absence of a relapse, were identified in 183 and 350 of the patients in the placebo and ocrelizumab arms, respectively.
Time to onset of 12-week confirmed disability progression (CDP) was delayed in a quarter of the overall population (hazard ratio, 0.76; 95% confidence interval, 0.59-0.98). Risk reduction was greater in the presence of T1 Gd+ lesions at baseline (HR, 0.65; 95% CI, 0.40-1.06), compared with patients harboring T1 Gd- lesions at baseline (HR, 0.84; 95% CI, 0.62-1.13). A similar pattern was evident for time to onset of 24-week CDP.
The changes in timed 25-foot walk from baseline to week 20, and in brain T2 hyperintense lesion volume from baseline to week 120 were significantly reduced overall by treatment. Reductions in walk time and lesion volume were apparent in the T1 Gd+ and Gd- lesion subgroups, with similar percentage change. In the overall study, ocrelizumab significantly slowed decline in brain volume from weeks 24 to 120, and slowed declines were also evident in the T1 Gd+ and Gd- lesion subgroups, compared with placebo.
The findings warrant further studies powered to assess the apparent treatment benefit in patients with Gd+ lesions – who are likely relapsing – at baseline. If the findings hold, stratifying patients prior to treatment based on MRI of T1 Gd+ lesions could help to guide ocrelizumab treatment.
Gadolinium normally cannot pass from the bloodstream into the brain or spinal cord because of the presence of the blood-brain barrier. Active inflammation in the brain or spinal cord during a MS relapse disrupts the barrier. Gadolinium enters the brain or spinal cord and permeates into MS lesions, which appear bright on MRI.
The study was funded by Hoffmann-La Roche/Genentech. Dr. Wolinsky disclosed receiving consulting fees; compensation for service on steering committees or data monitoring boards; and/or research support from many companies that market MS drugs, including Hoffmann-La Roche/Genentech.
