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The FDA ( Food and Drug Administration ) has approved Rituxan ( Rituximab; in Europe: MabThera ), in combination with glucocorticoids ( steroids ), to treat patients with Wegener’s granulomatosis and microscopic polyangiitis, two rare disorders that cause blood vessel inflammation ( vasculitis ).

Vasculitis in patients with Wegener’s granulomatosis and microscopic polyangiitis, can lead to tissue damage. Wegener’s granulomatosis mostly affects the respiratory tract ( sinuses, nose, trachea, and lungs ) and kidneys, while microscopic polyangiitis commonly affects the kidneys, lungs, nerves, skin, and joints. Both of these diseases affect people of all ages and ethnicities, and both genders. The causes of these disorders are unknown, and both are considered orphan diseases because they each affect less than 200,000 people in the United States.

Rituximab is an antibody that is manufactured through biotechnology methods. The drug works by greatly reducing the number of specific immune cells in the blood, known as B cells.

The safety and effectiveness of Rituxan was demonstrated in a single controlled trial, in which 197 patients with Wegener’s granulomatosis or microscopic polyangiitis, were assigned at random to receive either Rituximab plus glucocorticoids once a week for four weeks or oral Cyclophosphamide plus glucocorticoids daily to induce remission. After six months, 64% of patients treated with Rituximab had complete remission compared to 53% of patients treated with Cyclosphosphamide.

Retreatment with Rituximab was not formally evaluated; therefore, the safety and efficacy of retreatment with subsequent courses of Rituximab has not been established. More data are needed to determine the safety of more than one course of Rituximab and long term safety of use of Rituximab in patients with Wegener’s granulomatosis and microscopic polyangiitis. These questions will be further evaluated in a required post-marketing study.

Rituxan carries a Boxed Warning for infusion reactions, which can occur during infusion or within 24 hours afterwards. Other Boxed Warnings for Rituxan include rashes and sores in the skin and mouth ( severe mucocutaneous reactions ); and progressive multifocal leukoencephalopathy, a brain infection that generally is fatal.
Rituxan is not recommended for use in patients with severe, active infections.

The most common side effects in study participants with Wegener’s granulomatosis and microscopic polyangiitis included infection, nausea, diarrhea, headache, muscle spasms, and anemia.

Rituxan, which has been marketed since 1997, is also indicated for the treatment of patients with non-Hodgkin’s lymphoma, chronic lymphocytic leukemia, and rheumatoid arthritis.

Source: FDA, 2011