PO:02:024 | Development of anti-drug antibodies in patients with peripheral and/or axial spondyloarthritis treated with infliximab or adalimumab: a monocentric cross-sectional study

Gabriele Amati¹, Gilda Sandri^1|2, Alessandra Melegari³, Benedetta Bongiovanni^1|2, Giovanni Ciancio², Martina Orlandi^1|2, Ottavio Secchi¹, Dilia Giuggioli^1|2 | ¹Struttura complessa di Reumatologia, Azienda Ospedaliero-Universitaria Policlinico di Modena; ²Cattedra di Reumatologia, Università degli studi di Modena e Reggio Emilia; ³Dipartimento di medicina di laboratorio, Ospedale di Baggiovara, AUSL di Modena, Italy

Background.The evaluation of the prevalence of anti-drug antibodies (ADABs) against infliximab (IFX) or adalimumab (ADA) in a monocentric cohort of patients affected by axial and/or peripheral spondyloarthritis (SpA), the variables associated with this phenomenon, the frequencies of suspected drug-related adverse events (DRAEs), and the frequencies of subsequent therapeutic choice. Materials and Methods. Cross-sectional study. All patients affected by axial and/or peripheral SpA (ASAS 2009/2011) who underwent a blood sampling (baseline) for IFX or ADA ADABs serum measurement for a suspected DRAEs or a disease relapse in the period time between 01/01/2020 and 01/01/2025, were included. Demographic and clinical data, and previous treatments at baseline, and subsequent therapeutic choices, were retrospectively gathered. Results. Forty patients (M:F 1:1, median age 51.6 (IQR 19.1)) affected by SpA (peripheral 50.0%, axial 35.0%, both 15.0%) were selected. Median disease duration was 8.3 (IQR 8.6) years. PsO and IBD were present in 32.5% and 12.5% of cases, respectively. ADABs serum measurement for IFX and ADA were 10/40 (25.0%) and 30/40 (75.0%), respectively. Median BASDAI and DAPSA at baseline were 4.4 (IQR 3.8) and 16.8 (IQR 6.8), respectively. An active axial (BASDAI>4) and/or peripheral (DAPSA>4) disease was present in 60% (12/20) and 92.3% (24/26) of cases, respectively. Median bDMARD treatment duration was of 2.5 years (IQR 4.5). Overall positivity for ADABs was 17.5% (IFX-ADABs 1/10, 10.0%, ADA-ADABs 6/30, 20.0%). Spearman matrix of correlation revealed a negative correlation between ADABs titer and the relative drug titer (ρs=-0.590, p<0.0001). Positivity for ADABs was associated to HLA-B27 negativity (p=0.036) and a lower median age (p=0.022). None of ADABs positive patients were under concomitant cDMARDs treatment (0.0% vs 27.3%, p=0.174). Reasons for ADABs serum measurement were secondary failure in 75.0% of cases and suspected DRAEs in 25.0% of cases. Ten AEs were recorded: 2 cases of arthritis, 1 case of psoriasis-like rash, 3 cases of hypertransaminasemia, 1 case of suspected uveitis, 1 case of suspected neuropathy, 1 case of suspected drug-induced lupus erythematosus, and 1 case of depression relapse. After blood sampling for ADABs measurement, in 35.0% of cases the treatment remained unchanged, in 32.5% was switched into another TNFαi (61.5% Etanercept, 23.1% Certolizumab, 15.4% Golimumab), and 32.5% swapped to another mechanism of action (53.8% IL17A inhibitor, 38.5% JAK inhibitor, 7.7% IL23 inhibitor). Conclusions. ADABs positivity is a frequent phenomenon in SpA patients treated with TNFαi. In our cohort, ADABs positivity was associated with younger age and HLA-B27 positivity.