TOPLINE:

Patients with ANCA-associated vasculitis who were treated with rituximab showed reduced serological responses to pneumococcal vaccination, but responses improved in those who later received a boost with a 23-valent pneumococcal polysaccharide vaccine (PPV-23).

METHODOLOGY:

• Researchers enrolled 105 patients with ANCA-associated vasculitis in remission into the phase 2b, open-label ACQUIVAS trial.
• A total of 53 patients have been treated with rituximab at least 4 months prior to screening, and 52 have been treated with other immunosuppressive therapies, including azathioprine, mycophenolate mofetil, or methotrexate.
• Participants were vaccinated first with the 13-valent conjugate polysaccharide vaccine, then at 6 months a subset of patients who had not received PPV-23 within 5 years were given a boost with PPV-23.
• The primary outcome was a twofold increase in ≥ six of 12 pneumococcal serotype-specific antibodies at 1 month after each vaccine dose.

TAKEAWAY:

• Only 7.7% of patients treated with rituximab achieved the primary outcome of a twofold increase in serotype-specific antibodies compared with 44.7% of patients treated with other immunosuppressants (P < .001).
• The booster dose of PPV-23 increased antibody responses in the rituximab-treated group so that by 7 months after baseline, 22.6% of those in the rituximab group and 54.5% of those in the nonrituximab group had achieved the primary outcome.
• Overall, 48% of patients with ANCA-associated vasculitis failed to achieve a twofold increase in serotype-specific antibodies compared with a previously established failure rate of 27.2% in the general population older than 50 years.

IN PRACTICE:

“These data indicate that either alternative vaccine strategies or alternative strategies to protect these patients from pneumococcal disease are required,” said first author of the study, Michael Chen-Xu, MD, of the University of Cambridge in Cambridge, England.

SOURCE:

The study was conducted by Vasculitis UK, the University of Cambridge, the University of Birmingham, and the NHS Foundation Trust, and presented at the 22nd International Vasculitis Workshop (IVW) 2026 in Melbourne, Australia.

LIMITATIONS:

The researchers did not mention limitations of the trial.

DISCLOSURES:

The trial was funded by Versus Arthritis. No conflicts of interest were declared.