Switch to rituximab shows anti-inflammatory effect in relapsing-remitting MS

By Lucy Piper

Rituximab may be an attractive treatment option for patients with relapsing-remitting multiple sclerosis (MS), suggest phase II study findings showing its efficacy in controlling inflammatory activity.

"We provide Class IV evidence for equal or superior inflammatory control measured by MRI [magnetic resonance imaging] parameters and CSF-NFL [cerebrospinal fluid neurofilament light chain] during the first year when rituximab was used as an alternative to first-line injectable therapies in a realistic, real-life setting", say the researchers.

The drug, an anti-CD20 monoclonal antibody that depletes B lymphocytes, is generally well tolerated and no unexpected adverse events were seen in the current study.

Three of six serious adverse effects were considered drug related - two cases of pyelonephritis and one case of influenza - but these resolved following hospitalisation.

The 75 patients with clinically stable relapsing-remitting MS were switched to rituximab from the first-line injectables interferon (IFN)-β and glatiramer acetate (GA).

Following a 3-month run-in period, two 1000 mg intravenous doses of the anti-CD20 therapy were given 2 weeks apart.

Only one of the 75 patients reported a clinical relapse during the first year of treatment and changed to a different therapy. Ten of 72 patients with MRI data available had gadolinium-enhancing lesions detected during the run-in period, but these were no longer present after treatment.

Indeed, the overall number of gadolinium-enhancing lesions fell from an average of 0.37 before treatment switch to 0.03 after 6 months of rituximab, while the number of new or enlarged T2 lesions dropped from 0.28 to 0.01 after 12 months.

Lumbar punctures from 70 patients showed a significant 21% reduction in CSF-NFL levels, dropping from 491 ng/L before initiating rituximab to 387 ng/L 12 months after.

CSF-NFL levels tend to increase with age, note Pierre de Flon (Östersund Hospital, Sweden) and colleagues in Neurology, and so this change is unlikely to represent a natural evolution of this marker. It indicates that "rituximab treatment may yield a better protection from irreversible [central nervous system] damage than IFN/GA", they add.

The effect of rituximab started to wane after 2 years, with clinical recurrence of activity in four patients fulfilling the criteria for treatment failure.

"This, together with an increase, although not statistically significant, in both MRI activity and CSF-NFL levels, indicates that the protective effect from a single course of 2 x 1,000 mg rituximab lasts for more than 1, but less than, 2 years", say the researchers.

"This agrees with data that describe recurrence of B cells occurring 6-12 months after depletion with rituximab. The optimal dose and dosing frequency, as well as whether repeated doses over time may induce long-term remission in MS, need to be studied further."

Source: Neurology 2016; Advance online publication

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