FDA Updates Rituximab Label, Removing Warning About Retreatment

The US Food and Drug Administration (FDA) has approved a label update for rituximab (Rituxan) for added information about follow-up treatment for adult patients with granulomatosis with polyangiitis and microscopic polyangiitis who have achieved disease control with induction treatment. The update removed a precaution about the safety and efficacy of retreatment with rituximab that had previously been in place.

Granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) are 2 types of ANCA-associated vasculitis (AAV), an inflammation of blood vessels largely affecting small blood vessels of the kidneys, lungs, and other organs. Rituximab is a CD20-directed cytolytic antibody that is administered as an intravenous infusion.

“Options for continued treatment in GPA and MPA, chronic autoimmune diseases in which patients experience periods of flares, are currently limited,” said Sandra Horning, MD, chief medical officer and head of Global Product Development for Genentech, in a statement. “As part of our commitment to support people living with rare diseases, we are pleased to provide updated prescribing information for Rituxan to help physicians make more informed decisions about therapeutic options for patients who have achieved disease control with induction treatment.”

The label update was approved based on results from MAINRITSAN, a randomized, controlled trial of rituximab along with glucocorticoids compared to azathioprine as follow-up treatment. A total of 115 patients (86 with GPA, 24 with MPA, and 5 with renal-limited AAV) in complete remission after receiving a regimen of cyclophosphamide—glucocorticoid were randomized to either 500 mg of rituximab on days 0 and 14 and at months 6, 12, and 18 or daily azathioprine until month 22.

Meeting the primary endpoint, by month 28, 5% of patients receiving the rituximab regimen (n = 3) and 29% of those receiving azathioprine (n = 17) had experienced a major relapse (hazard ratio for relapse, 6.61; 95% confidence interval, 1.56 - 27.96; P = .002).

The rituximab Prescribing Information lists the most common adverse reactions in clinical trials among patients with CPG and MPA as infections, nausea, diarrhea, headache, muscle

spasms, anemia, peripheral edema.

In 2011, the FDA approved rituximab for patients with granulomatosis with polyangiitis and microscopic polyangiitis with precautions about retreatment with rituximab because of a lack of data about multiple courses of the treatment.

Rituximab was first approved by the FDA for the treatment of non-Hodgkin’s Lymphoma in 1997. Subsequently it has also been approved for use in certain patients with chronic lymphocytic leukemia, rheumatoid arthritis, granulomatosis with polyangiitis, microscopic polyangiitis, and pemphigus vulgaris.

The FDA’s approval of rituximab for pemphigus vulgaris was supported by Priority Review, Breakthrough Therapy Designation, and Orphan Drug Designation. Rituxumab became the first biologic treatment for the autoimmune condition and the first advancement in treatment in 6 decades.

Data from the MAINRITSAN trial were published as “Rituximab versus Azathioprine for Maintenance in ANCA-Associated Vasculitis,” in NEJM.