COPENHAGEN — according to extension data out to 6 years.
By the most recent analysis of a phase 3 extension study, there were “fewer disability worsening events and greater likelihood of being progression free among those started on ofatumumab than those started on teriflunomide and switched,” reported Amit Bar-Or, MD, director of the Center of Neuroinflammation and Neurotherapeutics, University of Pennsylvania, Philadelphia.
Stated differently, if ofatumumab is delayed, it never fully compensates for the advantage of better early MS control in treatment-naïve patients, according to Dr. Bar-Or, who presented these data at the 2024 ECTRIMS annual meeting.
Anti-CD20 Disability Protection Already Seen in Pivotal Trial
In two phase 3 trials called ASCLEPIOS I and II that were published together several years ago in The New England Journal of Medicine, the anti-CD20 monoclonal antibody ofatumumab reduced the annualized relapse rate (ARR) by half (0.11 vs. 0.22). While ARR was the primary endpoint, ofatumumab was also associated with a 34% reduction (P = .002) in risk of confirmed disability worsening at 3 months (3mCDW) at a medium follow-up of 1.6 years.
After the completion of ASCLEPIOS I and II, the majority of both arms of the study were enrolled in the ALITHIOS extension study. Patients in ofatumumab arm have remained on their initially assigned drug. Patients in the teriflunomide group were switched. Characterized as the delayed ofatumumab group, they have been receiving the same 20-mg, once-monthly subcutaneous (SQ) dose of ofatumumab as those initially assigned to this drug. ALITHIOS will continue to follow both groups until 2028.
Patients have now been followed for up to 6 years. In the latest results presented at ECTRIMS, data were available for 690 patients on continuous treatment and 677 switch patients. Baseline characteristics of the two groups were similar. About half of each group were treatment naive when enrolled in the ASCLEPIOS trials.
Whether compared for 6-month confirmed disability worsening (6mCDW), 6-month progression independent of relapse activity (6mPIRA) or 6-month relapse-associated worsening (6mRAW), disease progression was consistently worse for those with delayed ofatumumab. The differences were most pronounced in those who were treatment naive when started on therapy.
Anti-CD20 MAB sustains Disability Protection for up to Years
For those who were treatment naive, the rates of 6mCDW at the most recent follow-up were 16.61% vs 23.74% (P = .033) for continuous and delayed ofatumumab, respectively. For the entire study, these rates were 21.09% versus 24.77%, respectively, which represented a strong trend (P = .063).
The relative rates for 6mPIRA (11.12% vs 16.75%) and 6mRAW (4.26% vs 4.82%) in treatment-naive patients also favored continuous over delayed ofatumumab, and the numerical advantage was also seen with up to 6 years of follow-up in the overall study population for 6mPIRA (15.45% vs 16.56%) and 6mRAW (5.24% vs 5.81%).
Translating these into freedom from disability, Dr. Bar-Or reported that more than 80% (83.4%) of patients on continuous ofatumumab were progression free for up to 6 years, a figure that exceeded the 76.3% free of progression in the delayed ofatumumab group.
On the basis of 6mPIRA, that absence of disability progression neared 90% (88.9%) on continuous ofatumumab relative to 83.3% for delayed ofatumumab.
An advantage for a reduction in disability accumulation for ofatumumab relative to teriflunomide was established at the end of the ASCLEPIOS I and II trial, but the latest follow-up shows that it is “sustained out to 6 years.” The advantage is achieved with no greater cost in adverse events during the early treatment period, according to Dr. Bar-Or, who noted that ofatumumab and teriflunomide were similarly well tolerated in ASCLEPIOS I and II.