Rekeland, Ingrid G, Fluge, Øystein, Alme, Kine et al. · Clinical therapeutics · 2019 · DOI
This study looked at whether the amount of a drug called rituximab in patients' blood predicted whether they would improve from ME/CFS symptoms. The researchers measured rituximab levels in 23 patients and found no clear connection between how much drug was in the blood and who felt better. Interestingly, none of the patients developed antibodies against the drug, which was a potential concern.
Understanding whether drug levels in the blood correlate with treatment benefit is crucial for evaluating whether rituximab is truly effective for ME/CFS or whether negative results reflect inadequate drug exposure. This study helps clarify the mechanisms of rituximab response and suggests that if this drug works for ME/CFS, it may not depend simply on achieving certain blood concentrations.
This study does not prove rituximab is ineffective for ME/CFS—only that drug concentration levels alone do not explain which patients improve and which do not. The observational design prevents causal inference about rituximab efficacy, and the small sample size limits generalizability. The findings also do not rule out other mechanisms of action or potential value in larger, more carefully controlled trials.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Rekeland, Ingrid G, Fluge, Øystein, Alme, Kine, Risa, Kristin, Sørland, Kari, Mella, Olav, et al. (2019). Rituximab Serum Concentrations and Anti-Rituximab Antibodies During B-Cell Depletion Therapy for Myalgic Encephalopathy/Chronic Fatigue Syndrome.. Clinical therapeutics. https://doi.org/10.1016/j.clinthera.2018.10.019
BibTeX
@article{mecfsatlas-rekeland-2019-rituximab-serum,
author = {Rekeland, Ingrid G and Fluge, Øystein and Alme, Kine and Risa, Kristin and Sørland, Kari and Mella, Olav and de Vries, Annick and Schjøtt, Jan},
title = {Rituximab Serum Concentrations and Anti-Rituximab Antibodies During B-Cell Depletion Therapy for Myalgic Encephalopathy/Chronic Fatigue Syndrome.},
journal = {Clinical therapeutics},
year = {2019},
doi = {10.1016/j.clinthera.2018.10.019},
note = {PubMed: 30502905},
url = {https://www.mecfsatlas.com/evidence/rekeland-2019-rituximab-serum},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/rekeland-2019-rituximab-serum
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