Rituxan (rituximab) is a CD20-directed cytolytic antibody indicated for the treatment of patients with certain lymphomas and leukemia. It is also approved to treat autoimmune conditions such as rheumatoid arthritis. However, rituximab is often used off label for other cancers and autoimmune conditions. Unfortunately, the safety and efficacy of its off-label use is not clear.
At the 68th Annual American Academy of Neurology Meeting held April 15-21, Villa and colleagues reported on the use of rituximab in patients with neuromyelitis optica (NMO) and myasthenia gravis (MG)—2 rare autoimmune conditions for which rituximab may or may not be effective.
The researchers retrospectively reviewed the medical records of patients with NMO and MG attending Ramos Mejia Hospital in Buenos Aires, Argentina, between January 2007 and July 2015.
There were 55 NMO and 130 MG patients in total. Of those, 11 NMO and 3 MG patients were treated with rituximab; each received a total dose of 2 g of intravenous rituximab divided into 2 biweekly infusions.
The researchers noted that 5 of 11 (45%) patients with NMO and 1 of 3 (33%) patients with MG experienced disease exacerbation within the first month of their first rituximab infusion.
Of those 5 NMO patients, 2 had spinal-cord relapses, 2 had optic-nerve relapses. and 1 developed encephalopathy with multiple new gadolinium-enhancing lesions throughout the cerebrum. The 1 patient with MG who relapsed experienced muscle weakness during the first week post induction.
The researchers concluded that it seems plausible that rituximab-treated patients are at risk for post rituximab relapse. They hypothesized that overlap of immunosuppression with rituximab would yield better results.
Villa A, Aguirre F, Melamud L. Disease exacerbation after rituximab induction in neuromyelitis optica and myasthenia gravis. Poster presented at: 68th Annual American Academy of Neurology Meeting; April 15-21, 2016; Vancouver, BC. Abstract P4.153.