When the Food and Drug Administration approved avacopan (Tavneos) as an adjunctive treatment for severe, active antineutrophil cytoplasmic autoantibody (ANCA)–associated vasculitis (AAV) in October 2021, the oral complement C5a receptor inhibitor was hailed by its developer, ChemoCentryx, as a “new hope” for patients with the disease.
But avacopan’s novelty as a new drug for the rare diseases granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), coupled with its approval as an adjunctive to standard therapy, including glucocorticoids, rather than strictly as a glucocorticoid-sparing agent as it was tested, has so far led to little reported real-world experience with the drug.
M. Alexander Otto
Dr. Anisha Dua
In the phase 3 ADVOCATE trial, the pivotal trial that served as the basis for avacopan’s approval, 331 patients with active newly diagnosed or relapsing GPA or MPA received either avacopan or an oral prednisone taper over 20 weeks on a background of cyclophosphamide followed by azathioprine or rituximab. The results of the trial showed avacopan was noninferior to the group that received prednisone taper for remission at 26 weeks and superior to prednisone taper for sustained remission at 52 weeks, but the FDA was concerned that its complex design made it difficult to define the clinically meaningful benefit of avacopan and its role in the management of AAV.
The FDA noted that, in the avacopan arm of the trial, 86% of patients received glucocorticoids outside of the study protocol. Despite this, avacopan reduced the cumulative glucocorticoid dose over the trial’s 52 weeks by nearly two-thirds, compared with the prednisone group (1,349 mg vs. 3,655 mg).
The data also indicate a higher sustained remission rate at 52 weeks in patients who received induction with rituximab, compared with cyclophosphamide. But trial did not include a maintenance therapy dose of rituximab and is thereby not a good comparison against the standard of care, the FDA said. (ADVOCATE began enrolling patients prior to the FDA's 2018 approval of an expanded indication for patients with GPA or MPA who have achieved disease control after induction treatment.)
At the FDA’s Arthritis Advisory Committee meeting in May 2021, committee members were split on whether to recommend avacopan for approval. The committee voted 9-9 on whether the ADVOCATE trial showed efficacy supporting approval of avacopan, 10-8 in favor of whether the drug’s safety profile supported approval, and 10-8 in favor of the overall benefit-risk profile of avacopan for approval. But rather than give an indication to avacopan to reduce the use of glucocorticoids in adults with GPA or MPA, the agency approved avacopan as an adjunctive treatment for severe, active disease, noting in particular that avacopan “does not eliminate glucocorticoid use.”
The European Union’s marketing authorization for avacopan states its indication for use in combination with a rituximab or cyclophosphamide regimen for the treatment of adult patients with severe, active GPA or MPA and does not mention a role for reducing glucocorticoids. Avacopan will appear in forthcoming guidelines on management of AAV released by the European Alliance of Associations for Rheumatology.
In North America, the Canadian Vasculitis Research Network recently released an addendum to their guidelines on AAV specifically for avacopan, which includes recommendations to consider adding oral avacopan (30 mg twice daily) for induction of remission in patients with new or relapsing GPA or MPA who are also receiving cyclophosphamide or rituximab. The guidelines also recommend clinicians consider a glucocorticoid tapering schedule that aims for discontinuation at 4 weeks, and continuing avacopan for at least 1 year after induction therapy. The American College of Rheumatology guideline for AAV management, updated in 2021, acknowledges avacopan but did not consider its inclusion prior to FDA approval.
There have been few real-world studies of how patients with AAV are responding to avacopan, but recent studies from researchers in the Netherlands and in France have evaluated prednisone tapering and clinical outcomes.
Anisha B. Dua, MD, an associate professor of rheumatology at Northwestern University, Chicago, said those real-world studies “seemed to re-enforce the findings from the ADVOCATE study demonstrating the efficacy of avacopan in severe disease with steroid-sparing effects.”
Dr. Carol Langford
However, Carol Langford, MD, MHS, director of the Center for Vasculitis Care and Research at the Cleveland Clinic, emphasized caution is needed when drawing conclusions about avacopan use outside formal studies.
“We are all interested in what other settings this might be used. I think those are things that really require formal investigation to really try and understand better as far as through a study process,” she said.