Genentech announced that the experimental monoclonal antibody ocrelizumab significantly reduced relapse rates after two years compared to the established MS treatment, Rebif® (interferon beta-1a, EMD Serono and Pfizer) in two phase III studies. Ocrelizumab is administered by intravenous infusion every 6 months. The studies, known as OPERA I and OPERA II, included a total of 1,656 people with relapsing MS (people with relapsing-remitting MS and those with secondary-progressive MS who were experiencing relapses).
The results were announced in a June 30 press release. Data analysis is ongoing and the company expects to provide a full report at an upcoming medical meeting. The release stated that the company plans to submit these data to the FDA and European drug regulators for marketing approval in 2016. The results of an ongoing trial in people with primary progressive MS are expected to be announced later in 2015.
Background: Ocrelizumab binds to a molecule (CD20) on the surface of immune cells called B cells, and depletes them from the circulation. B cells have several functions including making antibodies, and they may play a role in the immune attacks on brain and spinal cord tissues in MS. Ocrelizumab is a “humanized” version of rituximab, a therapy for cancers and other disorders that has previously shown benefit in people with relapsing-remitting MS.
The Study: In each study, participants were randomly assigned to receive ocrelizumab (IV infusions every 6 months) or Rebif (44 micrograms injected under the skin three times weekly) for 96 weeks. Participants in the ocrelizumab group received an inactive placebo version of Rebif, and those in the Rebif group received an inactive placebo version of ocrelizumab.
In each study, the primary outcome being measured was the effect on relapse rate. Secondary outcomes included time to onset of sustained disability progression (an increase in the EDSS disability scale that is sustained for at least 12 weeks), change in disease activity on MRI scans, change in brain tissue volume, and safety and tolerability.
Results: According to the press release, treatment with ocrelizumab significantly reduced the relapse rate at the two year point compared with Rebif. Ocrelizumab also significantly reduced the progression of disability and disease activity on MRI scans. Results from other assessments were not included in the press release.
The most common “adverse events,” or side effects, were mild-to-moderate infusion-related reactions. The press release notes that the incidence of serious effects was similar in both treatment groups, but does not note what these events were.
Comment: “We look forward to seeing the detailed safety and effectiveness results from these large clinical trials of ocrelizumab,” says Bruce Bebo, PhD, Executive Vice President, Research at the National MS Society. “Having additional treatment options is important for people with MS, since the currently available therapies don’t work for everyone.”
Rebif is a registered trademark of EMD Serono and Pfizer.