JAN 10, 2012
Neuro-Ophthalmology/Orbit
The authors prospectively evaluated the long-term effect of rituximab treatment in 17 patients with myasthenia gravis with antibodies to MuSK or AChR who did not respond to prednisone. They found a long-term clinical benefit in most of them, and this benefit was particularly robust for MuSK myasthenia.
At the start of rituximab treatment all patients had shown no significant clinical improvement after treatment with prednisone and at least three second-line immunosuppressants. Rituximab was administered at the standard dose of 375 mg/m2 every week for four consecutive weeks and then monthly for the next two months. Repeat rituximab infusions were administered only when myasthenic symptoms reappeared and interfered with daily life activities.
After a mean post-treatment period of 31 months, 10 of the 11 AChR myasthenia patients improved but six of them needed reinfusions. In contrast, all MuSK myasthenia patients achieved remission or minimal manifestations status and no reinfusions were needed. Consequently, in the MuSK group, prednisone doses were significantly reduced and concomitant immunosuppressants could be withdrawn.
Clinical improvement was associated with a significant decrease in antibody titers only in the six MuSK patients. At the last follow-up, MuSK antibodies were negative in three of these patients and showed a decrease of more than 80 percent in the other three.
The authors conclude that a prospective, double-blind, randomized, controlled trial should be conducted to explore the use of ritixumab as an initial treatment.