Rituximab trial discussed, ‘Cure Talk: conversations about new treatments and clinical trials’ website, 19 October 2011

From ‘Cure Talk: conversations about new treatments and clinical trials’, 19 October 2011 (Story by Kate Benson).

A serendipitous discovery and reported in a journal article may have led scientists to a possible treatment for ME/CFS. This breaking story makes it a rather busy month for Chronic Fatigue Syndrome (CFS), given the earlier stories on off-label use of Anti-retrovirals for treating this condition.

Norwegian researchers found that Rituximab, an anti-cancer drug used to treat Hodgkin’s disease, also caused remission of symptoms in a patient who had co-morbid ME/CFS.

The authors concluded that the results of the current clinical trial suggest that CFS is an autoimmune disease and may be consistent with the gradual elimination of auto antibodies preceding clinical responses.

A small 2009 study with three patients led to the present double-blind, placebo-controlled phase II study with 30 ME/CFS patients all diagnosed by a neurologist using the 1994 Fukuda research definition. Twenty eight of the patients also retrospectively met the Canadian Consensus Definition.

Summary of the Study Results

In this study, sixty seven percent of the patients treated with infusions of Rituximab had significant overall clinical response lasting from eight to 44 weeks during the 12-month study.

No serious side effects were experienced by patients although patients with other diseases have reported serious adverse events including rarely death.

Two of the patients in the placebo group did not meet the Canadian criteria and the authors questioned whether they actually had ME/CFS.
The authors stated that a placebo response to saline was experienced by one of these patients who had only slight cognitive symptoms and also reported marked mood disturbances.

How does Rituximab work

Rituximab works by destroying white blood cells that make antibodies. White blood cells are part of the immune system response and ME/CFS studies point to chronic activation of the immune system following an acute infection. A clear or possible clinical infection preceding CFS onset could be identified in 73% and 67% of the patients in the Rituximab and placebo groups, respectively according to the authors, however, patients with ongoing infections were excluded from the trial.

Like all immune cells, white blood cells are created in the bone marrow. The NIAID reports, that at the heart of the immune system is the ability to distinguish between self and non-self. Immune cells and other cells in the body usually coexist peaceably in a state known as self-tolerance. In abnormal situations (such as an autoimmune disease), the immune system can wrongly identify self as non-self and execute a misdirected immune attack.

A limitation of this study is the lack of predetermined exact definitions of clinical response with respect to duration and extent of improvement. According to the authors, an alternative explanation for the observed clinical improvement from B-cell depletion could be elimination or reduction of B-lymphotrophic viruses such as cytomegalovirus (CMV) or Epstein-Barr virus (EBV).

Two new open-label phase-II studies in Norway (Study 1, Study 2) investigating Rituximab treatment with two infusions two weeks apart (as in the present study) followed by maintenance Rituximab infusions at 3, 6, 10 and 15 months, are being conducted to further explore this treatment principle in CFS.

The anti-cancer drug is also being investigated for treatment of rheumatoid arthritis, lupus/systemic lupus erythematosus, Sjogren’s syndrome multiple sclerosis, and Behcet’s disease.

Fluge Ø, Bruland O, Risa K, Storstein A, Kristoffersen EK, et al. (2011) Benefit from B-Lymphocyte Depletion Using the Anti-CD20 Antibody Rituximab in Chronic Fatigue Syndrome. A Double-Blind and Placebo-Controlled Study. PLoS ONE 6(10): e26358. doi:10.1371/journal.pone.0026358

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