In fact, their annual relapse rates have fallen even further during the extension study than during the trials.
The study, “Preliminary Results of the OPERA I and OPERA II Open-Label Extension Study,” was presented at the Annual Meeting of the Consortium of Multiple Sclerosis Centers in New Orleans, May 24-27. The results covered 96 weeks of the 144-week extension study.
Ocrevus, a humanized anti-CD20 monoclonal antibody, slowed progression of MS in the Phase 3 OPERA I (NCT01247324) and OPERA II (NCT01412333) trials. Many of those who received the therapy opted to take part in the OLE extension trial.
The primary objective of the OPERA studies was to see whether Ocrevus would lower relapsing MS patients’ annual relapse rate. Participants received either 600 mg of intravenous Ocrevus every 24 weeks or 44 μg of injected Rebif (interferon beta-1a) three times a week for 96 weeks.
Unlike in the OPERA studies, both the researchers and participants in the extension study are aware that all patients are receiving Ocrevus.
The extension study’s primary yardstick will be the annual relapse rate at 144 weeks among relapsing MS patients who received Ocrevus or Rebif in the OPERA trials, followed by Ocrevus in the OLE phase.
Preliminary results at 96 weeks showed that patients switching from Rebif to Ocrevus in the extension study had a lower annual relapse rate. The rate among OPERA I patients who had taken Rebif fell from 0.245 relapses per year to 0.092 in the extension study. The rate among OPERA II patients who had taken Rebif fell from 0.254 to 0.115.
Patients treated with Ocrevus in both the OPERA and extension trials also showed a lower annual relapse rate. The rate dropped from 0.136 in the OPERA I trial to 0.118 in the extension study, and from 0.138 in the OPERA II trial to 0.100 in the extension study.
Overall, “patients who originally received ocrelizumab in the OPERA studies continued to have favorable unadjusted annualized relapse rate outcomes in the OLE,” the researchers wrote. “Patients who switched from interferon beta-1a to ocrelizumab in the OLE rapidly experienced unadjusted annualized relapse rate outcomes consistent with those of patients who received continuous ocrelizumab.”
Ocrevus received U.S. Food and Drug Administration approval on March 28, 2027, as the first treatment for both relapsing MS and primary progressive MS.