On November 19th, I went to the local hospital outpatient infusion clinic to receive the first dose of Rituxan® (rituximab). This Thursday I go back for the second dose which will complete one round of treatment. Rituxan in combination with methotrexate is indicated for the treatment of adult patients with moderately to severely active rheumatoid arthritis who have had an inadequate response to one or more TNF antagonist therapies (such as Humira, Enbrel, or Remicade).
Those of us living with multiple sclerosis CANNOT use one of the anti-TNF disease-modifying anti-rheumatic drugs (DMARDs) which are commonly used in the treatment of RA or other rheumatic diseases. This is because the anti-TNF drugs are known to increase disease activity in patients who have a demyelinating disease such as MS. Although I am officially using Rituxan as a treatment for RA, it is the hope of my rheumatologist, neurologist, and myself that Rituxan may be effective in slowing down my experience with MS relapses.
What is Rituximab?
Rituximab is a chimeric (mouse/human) monoclonal antibody directed at the antigen protein CD20, which is found on only pre-B and mature B cells. CD20 is not found on plasma cells, stem cells, or pro-B cells, and therefore eliminating the CD20 positive population does not prevent recovery of mature B cells or immunoglobulin production. B cells are a type of white blood cell, specifically a lymphocyte, which is responsible for producing immunoglobulins. Rituximab was initially FDA approved for the treatment of B cell lymphoma in 1997 and received approval for RA in 2006. It is NOT approved for use in multiple sclerosis.
Rituxan is administered as two 1000mg intravenous (IV) infusions separated by 2 weeks, a process which is repeated every 24 weeks or based on clinical evaluation, but not sooner than every 16 weeks. Premedication with an antihistamine (such as Benadryl®) and acetaminophen (Tylenol®) is recommended to reduce the incidence and severity of infusion-related reactions. For RA patients, glucocorticoids such as methylprednisolone (Solumedrol) 100mg IV or its equivalent are administered 30 minutes prior to each infusion.
Rituximab and Multiple Sclerosis
Rituxan has been tested in clinical trials for the treatment of primary progressive multiple sclerosis (PPMS) and relapsing-remitting multiple sclerosis (RRMS). It is with great interest that I have followed the presentations given at various neurological events in reference to B-cell therapy and MS. Oftentimes, we can learn what the results of the trials were many months before the results are published in journals.
Regarding the PPMS trial, it was a great disappointment to learn that the results were a statistical failure, although further analysis shows that rituximab was effective in a select group of patients. Trial results were recently published in the Annals of Neurology.
