Lower Doses of Rituxan Equally Effective at Controlling AAV, Study Suggests

Lower doses of Rituxan (rituximab) appear to be as safe and effective as the standard Rituxan regimen for inducing remission in ANCA-associated vasculitis (AAV) patients, a retrospective Japanese study suggests.

The study, “Low-dose rituximab as induction therapy for ANCA-associated vasculitis,” was published in Clinical Rheumatology.

AAV consists of a group of autoimmune inflammatory disorders that can be deadly. Treatment is done with immunosuppressive therapy that decreases the activity of the immune system. Often, this therapy includes glucocorticoids in combination with Rituxan.

Rituxan is an antibody that targets a receptor on B cells — cells that make self-targeting antibodies that drive inflammation in AAV. Its optimal dosage is based on studies in lymphoma patients, yet recent evidence from other areas, including rheumatoid arthritis and kidney transplantation, suggests that lower dosages might be equally effective for AAV.

To test this, researchers retrospectively analyzed 28 AAV patients who had been treated with a standard Rituxan regimen, or with low-dose Rituxan. The standard regimen consisted of a 375 mg/m² dose, given once a week for four weeks; the low-dose was given once a week for only two weeks.

Although the groups were similar in many clinical respects, there were some notable differences; for example, significantly more elderly patients were in the low-dose group.

The researchers compared complete response rates between the two groups and found that there was no significant difference one year after treatment — 88.2% for standard Rituxan and 90.2% for low-dose.

There was also no significant difference in relapse rates after a year — 13.3% versus 20%. The incidences of disease-specific phenotypes that were assessed were also comparable between the groups.

There was no difference in the rate of serious adverse reactions between the two groups, although some side effects, including infection and anemia, were common in both, and there were serious infections that required hospitalization in both groups.

The researchers concluded that the low dosage of Rituxan seemed just as effective at controlling disease progression as the previously standard higher dosage. “This [low-dose Rituxan] regimen may improve the cost/benefit profile of RTX therapy for AAV,” the investigators said.

Because this study is limited by its retrospective nature and relatively small sample size, further studies and trials will be needed to validate the results.