Prospective controlled study of the recombinant zoster vaccine in autoimmune rheumatic disease: robust seroconversion despite intravenous cyclophosphamide

BACKGROUND: Recombinant zoster vaccine (RZV) prevents shingles in autoimmune rheumatic diseases (ARD), but intravenous cyclophosphamide (IVCYC) impact on immunogenicity is unknown. Given cell depletion/cytotoxicity, IVCYC is expected to induce profound immunogenicity impairment, we therefore evaluated its impact. METHODS: This subanalysis of prospective, randomized, placebo-controlled trial included ARD patients receiving IVCYC (ARD-IVCYC) compared with patients without IVCYC (ARD-no IVCYC) and healthy-controls. RZV was administered in two doses. Humoral response (≥4-fold), geometric mean titers (GMT) and cellular response were assessed after second dose. Disease activity and adverse events (AEs) were recorded. RESULTS: Forty-one ARD-IVCYC, 164 ARD-no IVCYC, and 164 controls were included. Seroconversion did not differ between ARD-IVCYC and ARD-no IVCYC (91.9% vs. 91.5%) and were lower than controls (99.4%, p = 0.022). Post-vaccination GMTs were comparable between ARD groups (p > 0.999), but lower than controls (p = 0.006). Cellular response and ARDs flares did not differ between groups (p > 0.05), with no severe AEs. CONCLUSION: RZV elicited >90% humoral response in IVCYC-treated patients, supporting it during IVCYC when warranted (NCT05879419).