FDA Expands Approval of Rituxan as Remission Maintenance Treatment for GPA and MPA Patients

Inês Martins, PhD avatar

by Inês Martins, PhD |

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MANDARA Phase 3 trial underway

The U.S. Food and Drug Administration has approved a label update for Rituxan (rituximab) to include information for patients with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) who have achieved disease control after induction treatment.

A combination of Genentech‘s Rituxan and glucocorticoids, Rituxan has been approved since 2011 for patients with these two conditions. But the medicine was only prescribed to induce remission, as no data existed supporting Rituxan’s continued use as a remission maintenance treatment.

With the label update, physicians are now able to use Rituxan for maintenance of remission in GPA and MPA patients.

“Options for continued treatment in GPA and MPA, chronic autoimmune diseases in which patients experience periods of flares, are currently limited,” Sandra Horning, MD, chief medical officer and head of Global Product Development, said in a press release. “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 update was based on data from MAINRITSAN (NCT00748644), a Phase 3 trial that examined the long-term safety and efficacy of Rituxan versus the immunosuppressant azathioprine in patients who had achieved disease remission.

The study included 115 patients  — 86 with GPA, 24 with MPA, and 5 with ANCA-associated vasculitis limited to the kidneys  — who were in remission after receiving glucocorticoids and cyclophosphamide.

Patients were randomly assigned Rituxan 500 mg  — a total of five infusions  — or azathioprine, given at a 2 mg/kg dose every day for 12 months, then progressively tapered until its discontinuation at month 22.

All patients received corticosteroids, starting at induction therapy, at a daily dose of 1 mg/kg, which was gradually tapered for a mean of 18 months since diagnosis.

The trial’s main goal was the occurrence of major relapses after 28 months, defined as a reappearance or worsening of disease and involvement of at least one major organ, a life-threatening complication, or both.

While only 5% of patients receiving Rituxan experienced a major relapse, 29% of those on azathioprine did.

Recently, the French Vasculitis Study Group  — which conducted the trial  — reported long-term data from MAINRITSAN. After five years, 71.9% of patients in the Rituxan arm had not experienced a major relapse, compared to 49.4% of those assigned azathioprine.

Also, more patients on Rituxan  — 57.9% vs. 37.2%  — had not experienced a minor relapse, defined as the reappearance or worsening of AAV requiring mild treatment intensification.

Overall, Rituxan delayed relapse or toxicity by 12.6 months compared to azathioprine, researchers found. Safety data was similar for both treatments, despite a higher rate of respiratory infections in the Rituxan group.

To date, Rituxan was approved in combination with glucocorticoids in a 375 mg/m² dose once weekly for four weeks, with the precaution that the safety and efficacy of re-treatment with Rituxan had not been established.

With the label update, that precaution has been removed and Rituxan may now be offered in combination with glucocorticoids to patients with GPA and MPA who have achieved disease control with induction treatment. The recommended regimen includes two 500 mg infusions given two weeks apart, followed by a 500 mg infusion every six months thereafter.