This is very interesting, and presents possibilities for the future. Thanks for posting. At this point, however, I'd be reluctant to take this route.
The possible side effects of this drug are pretty grim. I'm on a different genetically engineered biological, but really have no choice there as none of the less dangerous drugs helped me.
The potential side effects for levothyroxine are basically those of hyperthyroidism, plus allergic reactions.
The potential side effects for Rituxumab include skin problems that can be fatal and a leukodystrophy (a condition where the brain deteriorates and which is always fatal.) It has a red-box warning, which is the second highest level of warning the FDA uses. The odds of getting a severe allergic reaction are much higher with the biologicals than with older drugs. I'm glad they're doing research, but at this point it looks a little like going after a mosquito with a sledge hammer.