Avacopan Notches a Win in ANCA-Associated Vasculitis

Susan London

June 08, 2020

Avacopan, an investigational oral inhibitor of complement activation, is efficacious and safe for treating antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis, based on the results of the pivotal phase 3 ADVOCATE trial.

The trial results were reported in the opening plenary abstract session at the annual European Congress of Rheumatology, held online this year because of COVID-19.

"Standard of care for induction of remission includes high-dose glucocorticoids with either cyclophosphamide or rituximab. However, glucocorticoids are the major cause of treatment-related harm," noted lead investigator Peter A. Merkel, MD, MPH, chief of the division of rheumatology at the University of Pennsylvania, Philadelphia.

The 331 patients in the trial had active ANCA-associated vasculitis (granulomatosis with polyangiitis or microscopic polyangiitis), either new onset or relapsed, with positivity for either proteinase 3 or myeloperoxidase antibodies and moderate to high disease activity.

They were randomized evenly to double-blind avacopan 30 mg or tapering prednisone from 60 mg/day to zero over 20 weeks, each combined either with rituximab (Rituxan) or with cyclophosphamide followed by azathioprine. Avacopan (formerly called CCX168) is a selective antagonist of the complement C5a receptor that has orphan-drug designation from the Food and Drug Administration for this disease.

Trial results showed that avacopan was noninferior to prednisone with respect to the week 26 rate of remission on the Birmingham Vasculitis Activity Score, with an estimate of common difference of 3.4%. And it was superior to prednisone with respect to the week 52 rate of sustained remission, which required remission from week 26 onward, with an estimate of common difference of 12.5%.

The avacopan group also had less glucocorticoid-related toxicity and, among patients with preexisting renal disease, greater improvement in renal function.

"This large, randomized trial met both of its primary endpoints. Important secondary endpoints were also achieved, with a very acceptable safety profile," Dr. Merkel summarized.

Making Sense of the Results

The optimal duration of avacopan therapy is unclear, he noted. "We are still going to be learning how to use this drug, if it's approved, in routine practice. But the data from the second 6 months – from week 26 to week 52 – implies that there is ongoing benefit to being on avacopan after remission is achieved."

Avacopan worked similarly well regardless of disease status in ADVOCATE, according to Dr. Merkel. "We have not seen significant differences in efficacy of other drugs in our trials [by disease status], in the trials of ANCA-associated vasculitis. So I think we would treat moderate to serious disease similarly, whether it is new onset or recurrence, in terms of efficacy of the drug."

"The topline phase 3 data from ADVOCATE sort of even exceeded my expectations in terms of the ability to show not just noninferiority, but superiority of avacopan at week 52 in maintaining sustained remission," Lindsay S. Lally, MD, assistant professor of medicine at the Hospital for Special Surgery in New York, commented in an interview. "It's spectacular to treat patients with this serious vasculitis without any steroids or with very minimal steroids, and see superiority at a year. That is really game changing."

The ADVOCATE findings will likely pass muster with the FDA, according to Dr. Lally. "The bar that was set in terms of the coprimary endpoints was very stringent and in line with other registration trials, particularly the RAVE trial that led to the approval of rituximab," she elaborated. "I don't think there is any significant safety signal in the data related to avacopan.

"This study is going to move forward our ability to treat this disease effectively, as we have been able to do in some of our other vasculitis syndromes, by finding drugs that have significant steroid-sparing effects," Dr. Lally predicted.

Study Details

ADVOCATE results reported at the congress showed that the week 26 rate of disease remission was 72.3% with avacopan versus 70.1% with prednisone, with the difference falling within the 20% boundary for noninferiority (P < .0001) but missing the mark for superiority (P = .2387).

However, the week 52 rate of sustained disease remission was 65.7% versus 54.9%, respectively, yielding a difference in favor of avacopan that was statistically both noninferior (P < .0001) and superior (P = .0066).

At week 26, patients in the avacopan group had more favorable Glucocorticoid Toxicity Index scores for cumulative worsening (39.7 vs. 56.6; P = .0002) and for aggregate improvement (11.2 vs. 23.4; P = .008).

Among patients who had renal disease at baseline, those in the avacopan group had a greater increase in estimated glomerular filtration rate at week 52 (7.3 vs. 4.1 mL/min per 1.73 m2; P = .029).

"Particularly interesting is the fact that, even after week 26, when the patients were in remission, there was continued improvement in renal function," Dr. Merkel noted.

Overall, avacopan had a good safety profile. "This was a sick population with many complications, but there were no important safety signals of the study medication," he reported.

The avacopan and prednisone groups had a similar rate of severe adverse events (23.5% vs. 25.0%). But the former had lower rates of life-threatening adverse events (4.8% vs. 8.5%), adverse events potentially related to glucocorticoids (66.3% vs. 80.5%), deaths (1.2% vs. 2.4%), and deaths specifically caused by infection (0.6% vs. 1.2%).

The trial was sponsored by ChemoCentryx. Dr. Merkel disclosed receiving grant/research support from and consulting fees from ChemoCentryx, among other disclosures. Dr. Lally disclosed that she was an investigator in the trial.

SOURCE: Merkel PA et al. Ann Rheum Dis. 2020;79[suppl 1]:8, Abstract OP0011.

This story originally appeared on MDedge.com.

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