If it's being studied in the US? Not offical trials. But I'd say "yes" if you asked me if it was being used. But that's unofficial use.
But to fully answer that question. I would like to speak a bit broadly about it (many phrases borrowed from
Matthews) ...
During the late 1990s, two medical researchers at University College London began to wonder if B-cell therapy might hold the key to the debilitating disease rheumatoid arthritis (RA).
But there was massive opposition to these new ideas (as it always is when someone tries to change the status quo). They thought that B-cell therapy (Rituximab) could be more useful then existing therapies. The new theory was that B-cell therapy might be useful, or that B-cells had a central role in RA was refused. Their academic papers were rejected by journals as "obviously" wrong.
After much back and forth the pair managed to publish their idea in a medical journal, only to be met with deafening silence. Determined to make their case, they set up a small but demanding test, using rituximab to treat five patients with severe RA. The results were impressive; their condition improved dramatically. Yet attempts to publish the results in journals were rebuffed on the grounds that the study involved too few patients.
So the pair tried again, cobbling together enough money to treat 20 patients. Again, the results were impressive, with all but two of the patients showing dramatic improvements. It made no difference: the medical community remained utterly unimpressed. A long story short, in 2006 the medicine was approved for RA...
What we can learn from that is two things; lack of attention doesn't have to mean it's not right. And it takes (almost always) an eternitiy from idea, to small trial, to being able to get the medicine as a patient.
Much of the same is happening with MS now. Here is a quote on Rituximab and MS (
about the Hauser study):
The primary study endpoint was the total number of gadolinium-enhancing T1 MRI lesions seen at weeks 12, 16, 20 and 24.
The authors found that the total numbers of lesions was significantly reduced in rituximab-treated patients compared with placebo-treated patients at each of the study time points. The mean number of lesions at week 24 in the active treatment group was reduced by 91 percent to 0.5, compared with 5.5 for controls.
As for understandable reasons Rituximab is - by some - being used off label for MS today. But I guess most patients are told to not be so very open about it. In the same way as I am sure Rituximab is being used for MS, I am sure there are some doctors who offer Rituximab for some of their CFS patients. It's a large country, so although non common, I'd say for sure that there are some out there who do it.