The US Food and Drug Administration (FDA) has approved rituximab (Rituxan, Genentech) injection, in combination with glucocorticoids, to treat granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) in children aged 2 years or older. MPA is an uncommon disease characterized by vasculitis of small vessels. It can damage organ systems, most commonly the kidneys, lung, nerves, skin, and joints. In the United States, the annual incidence of MPA is 3.6 cases per 1 million persons. The prevalence is 1 to 3 cases per 100,000 population. GPA, another rare vasculitis, typically affects the nose, sinuses, throat, lungs, and kidneys. It's incidence is currently undetermined; prevalence is estimated to be 3 cases per 100,000 people. Rituximab is the first approved treatment for children with these rare types of vasculitis. "The Rituxan application for pediatric GPA and MPA was approved under a priority review, and with orphan designation, to fulfil an unmet medical need for these rare and serious diseases. Rituxan provides a treatment option that has not existed until now for children who suffer from these diseases," Nikolay Nikolov, MD, of the Division of Pulmonary, Allergy, and Rheumatology Products in the FDA's Center for Drug Evaluation and Research, said in a statement. Approval was based on an open-label, single-arm, uncontrolled study of 25 children and adolescents aged 6 to 17 years who had active GPA and MPA who were treated with rituximab. All participants received methylprednisolone prior to initiation of treatment. During a 6-month remission induction phase, patients were treated with rituximab and glucocorticoids. Those who did not achieve remission or who exprienced disease progression or an uncontrolled disease flare-up could receive additional treatment, including other therapies, at the discretion of the investigator. According to the FDA, for 14 of the 25 patients, disease was in remission by the 6-month mark. After 18 months, disease was in remission for all 25 patients. Additional pharmacokinetic (exposure) and safety information supported the use of rituximab in children aged 2 to 5 years with GPA/MPA, the FDA said. The safety profile in children with GPA and MPA was consistent with the known safety profile of rituximab in adults with autoimmune diseases, including GPA and MPA, the FDA said. The most common side effects of rituximab therapy are infections, infusion-related reactions, lymphopenia, and anemia. Patients who receive treatment with rituximab should be monitored for tumor lysis syndrome, a treatment complication in which tumor cells are killed off and are released into the bloodstream. Other complications may include cardiac adverse reactions, renal toxicity, and bowel obstruction and perforation, the FDA advises. The rituximab label has a boxed warning citing increased risks for fatal infusion reactions; potentially fatal severe skin and mouth reactions; hepatitis B virus reactivation that may cause serious liver problems, including liver failure and death; and progressive multifocal leukoencephalopathy, a rare, serious brain infection that can result in severe disability or death. Source
