In phase 3 trial, rituximab not associated with clinical improvement in patients with Myalgic encephalomyelitis/chronic fatigue syndrome

1. In this randomized controlled trial, B-lymphocyte depletion through rituximab did not significantly improve fatigue symptoms of patients with ME/CFS compared to the placebo group.

2. The authors did not observe significant differences between the placebo and the rituximab patient group with regards to self-reported function or fatigue severity scores throughout the study follow-up period.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a disease associated with significant morbidity, affecting 0.2% of the population based on Canadian consensus criteria. Patients with this condition often have symptoms of post-exertional malaise, pain and other sensory hypersensitivity, fatigue, sleep difficulty, and cognitive symptoms. One suggested treatment for this condition is B-lymphocyte depletion, which has shown promise in phase 2 studies. The authors of this study evaluated the effect of the monoclonal anti-CD20 antibody rituximab compared to placebo in patients with ME/CFS. The study found that there was no significant clinical improvement with respect to fatigue in patients treated with rituximab. One major limitation was that fatigue was self-reported and may therefore be subject to recall bias. Another potential limitation of the study is the study size and population demographics, as the results may not be applicable to all patient populations.

Click to read the study in Annals of Internal Medicine

Relevant Reading: Dietary and nutrition interventions for the therapeutic treatment of chronic fatigue syndrome/myalgic encephalomyelitis: a systematic review

In-Depth [randomized controlled trial]: The authors of this study conducted a randomized, placebo-controlled, double-blind, multi-center trial to evaluate the effect of B-lymphocyte depletion through rituximab on symptom management of ME/CFS. A total of 151 patients were included in this study, with ages ranging from 18 to 65 years who met the ME/CFS criteria. Patients were selected from 4 different university hospitals and 1 general hospital in Norway. The primary study outcome was fatigue score. The authors utilized several different validated questionnaires, including the Fatigue Severity Scale, to assess outcomes. Patients were assigned to either a placebo or rituximab group. During follow-up, there was no significant difference in average fatigue score between the placebo and rituximab groups. The average score difference was 0.02 (95% CI, -0.27 to 0.31). Similarly, no significant differences were observed between secondary outcome measurements of the groups. For instance, the difference in average score regarding function level was -0.21% (CI, -4.18% to 3.76%, P = 0.48).

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