Rituximab is a medication that targets immune system cells called B-cells, and can be used to treat sarcoidosis.
Rituximab, marketed as Rituxan and manufactured by Genentech, has been approved by the U.S. Food and Drug Administration (FDA) to treat rheumatoid arthritis; blood cancers involving B-cells, including chronic lymphocytic leukemia and non-Hodgkin’s lymphoma; granulomatosis with polyangiitis; and microscopic polyangiitis.
How rituximab works
Sarcoidosis is an inflammatory condition where the immune system is chronically overactive. This leads to clumps of immune cells, called granulomas, accumulating in and damaging various tissues and organs — including the skin, lungs, heart, and brain. The severity of symptoms of this disease varies, with some patients achieving spontaneous remission and others going on to experience frequent relapses or to develop a chronic, progressively worsening disease.
Research has shown that granulomas contain high numbers of B-cells and may be involved in enhancing the overactive immune response seen in sarcoidosis.
Rituximab is an anti-CD20 monoclonal antibody that specifically binds to a molecular marker known as CD-20, which is mostly found on the surface of B-cells. By targeting CD-20, rituximab can reduce excess B-cell production and lower inflammation.
Rituximab in clinical trials for sarcoidosis
Clinical trials have tested rituximab to treat sarcoidosis of the lungs, heart, and eyes.
Rituximab’s effectiveness in pulmonary sarcoidosis patients was assessed in an open-label Phase 2 clinical trial (NCT00855205). Ten people with pulmonary sarcoidosis for at least two years and still experiencing symptoms despite taking corticosteroids were given two infusions of 1g of rituximab two weeks apart. All were monitored for a year after the treatment.
Seven of these 1o patients showed improvements in lung function, as evidenced by better scores in either forced vital capacity and/or the six-minute walk test, both measures of breathing capability.
The study was performed by researchers at the University of Chicago and the University of Cincinnati, and the results were published in the European Respiratory Journal.
Another study, a multi-case study from a single medical center, documented the effectiveness of rituximab in three patients with chronic and treatment-resistant sarcoidosis.
The first patient, who had chronic pulmonary sarcoidosis, received six fortnightly treatments of 375 mg/m2 of rituximab. This regimen was able to stabilize symptoms and clinical parameters up to 1.5 years after the treatment.
The second patient, with skin, lung, and lymph node sarcoidosis, was given 1g of rituximab infusions each month for three months. This regimen was repeated half a year later, and ultimately the patient was able to reduce the dosage of corticosteroids needed to control the disease.
The third and final patient studied had severe ocular sarcoidosis and cutaneous sarcoidosis, and was able to achieve symptom relief with a combination of rituximab, cyclophosphamide, and infliximab.
Another study showed that a patient with severe refractory cardiac sarcoidosis, who did not respond to corticosteroid treatment and several other immunosuppressive medications, experienced improvement in heart function and symptoms after two infusions of 1g of rituximab, given two weeks apart. A second round of the same regimen given half a year later further stabilized her symptoms, and allowed the patient to reduce her use of corticosteroids.
A combination of rituximab and Cellcept (mycophenolate mofetil) has been shown to be effective in treating a condition known as autoimmune hemolytic anemia (AIHA). Patients with sarcoidosis are at risk of developing AIHA, a condition in which red blood cells are mistakenly destroyed by the immune system (a process referred to as hemolysis).
Other details
Common side effects of rituximab include fever, chills, headache, stomach issues (like nausea, heartburn, cramps, and diarrhea), flushing, night sweats, muscle and joint pain, weakness, and dizziness.
Patients may also experience infusions reactions — like fever, chills, itching, hives, cough, or difficulty breathing — after receiving this medication. Those developing any of these symptoms should inform a healthcare provider promptly.
Women taking rituximab who wish to have a baby should discuss this with their physician, as rituximab can harm a fetus.
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