(HealthDay News) — In patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), B-cell depletion using several infusions of rituximab over 12 months is not associated with clinical improvement, according to a study published online April 2 in the Annals of Internal Medicine.

Øystein Fluge, MD, PhD, from Haukeland University Hospital in Bergen, Norway, and colleagues examined the effect of the monoclonal anti-CD20 antibody rituximab versus placebo on ME/CFS. One hundred fifty-one patients aged 18 to 65 years were randomly assigned to treatment with either 2 infusions of rituximab, 500mg/m² of body surface area, followed by 4 maintenance infusions at 3, 6, 9, and 12 months, with a fixed dose of 500mg (77 participants) or placebo (74 participants).

The researchers found that the overall response rates were 35.1% and 26.0% in the placebo and rituximab groups, respectively (difference, 9.2 percentage points; 95% confidence interval, −5.5 to 23.3 percentage points; P=.22). There was no difference in fatigue score over 24 months or any of the secondary end points in the treatment groups. Serious adverse events were reported by 26.0% and 18.9% of patients in the rituximab and placebo groups, respectively.

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“This study highlights the importance of randomized and blinded clinical trials with a placebo group, especially in diseases that lack specific and sensitive biomarkers, have limited possibilities for objective end points, and rely mainly on self-reported symptom scores,” the authors write.

Several authors hold patents related to treatment of ME/CFS.

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