When’s Best to Re-dose Rituximab After Vasculitis Remission?

Maintaining remission in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis who have kept their autoantibodies in check after at least 2 years on rituximab therapy has proved challenging, but a team of nephrologists in Boston have reported that a longer-term strategy that uses a rise in B-cell levels as a threshold for rituximab infusions may be the better of two strategies at reducing relapse risks.

“The bottom line is with the B-cell strategy, which is that rituximab was redosed when the B cells recovered or started to recover, we only have a 6% rate in relapses by 3 years,” senior study author John L. Niles, MD, assistant professor of medicine at the Harvard Medical School and director of the Vasculitis and Glomerulonephritis Center at Massachusetts General Hospital in Boston, Massachusetts, told Medscape Medical News.

“Whereas in the other strategy, we were waiting for a serologic relapse and hoping we could prevent clinical relapses, but we still have about 30% rate of relapse by 3 years.”

Niles and his associates reported their findings from the MAINTANCVAS study (for MAINTenance of ANCA VASculitis) December 11, 2023, in Annals of the Rheumatic Diseases. Their single-center study compared two different treatment strategies in patients with ANCA-associated vasculitis in remission after completing at least 2 years of fixed-schedule rituximab therapy: an approach that reinfused rituximab upon B-cell repopulation, called the B-cell arm and a strategy that reinfused rituximab when serologic levels of ANCA increased significantly, which they called the ANCA arm. A total of 115 patients were randomly assigned to either arm.

Study Results

Median follow-up was 4.1 years from study entry. Throughout the study, 5 of 58 patients in the B-cell arm and 14 of 57 in the ANCA arm had relapses. According to Kaplan-Meier analysis, at 3 years after study entry, 4.1% of patients in the B-cell arm had a relapse vs 20.5% of patients in the ANCA arm. At 5 years, the respective relapse rates were 11.3% and 27.7%. Overall, four major relapses occurred in the B-cell arm and seven in the ANCA arm.

The COVID-19 pandemic caused the researchers to halt the study before it was fully enrolled, Niles said. The study also attributed high rates of serious adverse events (SAEs) in the B-cell arm to cases of COVID-19 in that study population. The overall number of SAEs was identical in both arms: 22 (P = .95). But the B-cell arm had six cases of COVID-19 vs one in the ANCA arm, including two deaths because of COVID-19.

The study findings provided insight into how to best individualize treatment in patients with ANCA-associated vasculitis, Niles said. “We will typically start with the B-cell strategy after 2 years, but to the extent that people have infections or hypogammaglobulinemia, we’ll start stretching a little longer on the B cells, and if the level is too high in terms of infection, we’ll stop and switch to the ANCA strategy,” he said.

He added, “Relapsers get a more strict B-cell strategy, and people with infections get much longer intervals or even switch entirely to the ANCA strategy.”

Because the study ended before it was fully enrolled, it was underpowered for subgroup analyses, Niles noted. One such potential subgroup was relapsing patients with interstitial lung disease as the primary clinical finding. “The interstitial lung disease doesn’t seem to respond as well to therapy as the other classic features of ANCA disease,” Niles said. “It’s the one part that’s the most problematic for the long run. It behaves differently, and there’s going to need to be more research on ILD. Fortunately, it’s a fairly small percentage of the total group, but it’s the most difficult part of this disease.”

Findings in Context

This study brings clarity on how to best manage patients with ANCA-associated vasculitis, Robert Hylland, MD, an assistant clinical professor of rheumatology at Michigan State University College of Osteopathic Medicine, told Medscape.

“Most of us have tried to discern from the literature that exists how to manage [ANCA-associated vasculitis]. There have been a number of different approaches, and they have changed over the course of time,” Hylland said. “But now this article helps us to understand how to proceed with this disease after we have induced remission. The ability to determine the validity of serology vs B-cell depletion was brought out very nicely in this article.”

The size of the study population was a strength of the study, Hylland said.

He credited the study authors for providing insight into using positive myeloperoxidase (MPO)- or proteinase 3 (PR3)-ANCA readings to guide treatment for relapses. The study defined a serologic ANCA flare in the ANCA arm as a fivefold increase in MPO and a fourfold rise in PR3.

“Many of us wouldn’t have recognized that a less than fivefold increase, for example, in the MPO could be watched for a while, where most of us would have been treating that serologic flare,” Hylland said.

The study also highlighted the difficulty of evaluating a patient who has neither a positive ANCA nor a significant increase in their B-cell counts and yet still has clinical signs and symptoms of a relapse, such as with granulomatosis with polyangiitis, also known as Wegener’s granulomatosis.

“A lot of physicians tend to feel a little more relaxed when they see their patient is serologically doing well and yet, when they come in, some of the subtle symptoms of Wegener’s could be ignored if you don’t recognize that there’s a considerable number who will come to you with having had treatment and still have negative serology,” Hylland said.

The study had no specific outside funding source. Niles and Hylland report no relevant financial relationships. Two co-authors report financial relationships with pharmaceutical companies.

Richard Mark Kirkner is a medical journalist based in the Philadelphia area.