ACTRIMS 2026 | B-cell concentration changes when switching from IV anti-CD20 antibodies to ofatumumab in MS: OLIKOS

OLIKOS was a Phase III study evaluating patients who were previously on IV anti-CD20 therapy, primarily ocrelizumab or rituximab, switching to sub-Q anti-CD20 therapy, which is ofatumumab. The study was conducted from 2020 to 2024, and the primary endpoint was to determine maintenance of efficacy after switching. In the original study, the outcome showed that patients who were switching from IV to sub-Q ofatumumab, there were zero GAD-enhancing lesions observed at the month 12 and meeting the primary endpoint. And the number of new and enlarging T2 lesions is only about 2.3%, which is consistent with all the anti-CD20 therapy studies. We didn’t see any change in EDSS scores. And then the annualized relapse rate remained low at 0.075. Treatment satisfaction was actually greatly improved from baseline to 12 months across all domains. And we didn’t really see any unexpected treatment emergent adverse events that was pretty similar to what we had seen in the pivotal Phase III studies. So overall, the main findings from the pivotal OLIKOS studies was that efficacy and safety was maintained when switching from IV anti-CD20 therapies to a subcutaneous anti-CD20 therapies.

What we presented at ACTRIMS in 2026 was a secondary endpoint, which we wanted to look at then what were the changes in B-cell concentrations. So with IV therapies being infused every six months, there’s some real world barriers to getting the treatment consistently every six months. So some people get infused a little bit later. There’s delays in treatment. There’s other factors that may change the concentration of how depleted your B-cells are, such as potentially BMI. And so in OLIKOS, we wanted to see if those B-cell concentrations, what would actually happen to them and what would change because with subcutaneous ofatumumab, instead of every six months, you’re getting an injection every four weeks. So there’s just more consistent dosing.

And the results of what we presented at ACTRIMS showed that there was less variable B-cell depletion. So at baseline, there was a wide range of B-cell counts. So certain, like a small number of patients had B-cell counts that were higher than the lower limit of normal. And then within that, the range was, there was some variability. And not surprisingly, those who had larger washout periods, meaning a longer delay from their prior infusions, had higher B-cell variabilities. We also saw more variability based on BMI and potentially self-identified race and ethnicity in the groups that identified as non-Hispanic Black or Hispanic Latino. During the OLIKOS study, then when we re-evaluated B-cell counts at month 6 and month 12, we actually saw that there was less variability, so that maintenance of B-cells, there was less variability, it seemed more consistently depleted. And this was, again, likely because instead of getting that infusion every six months where there’s more variability, because we’re getting dosed more consistently, there’s just better control of B-cell concentrations. So more stable pharmacodynamic effect that we’re seeing with the subcutaneous monthly injections as opposed to the greater variability seen with Q6 month IV infusions.

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