Background The anti-TNF therapy has been demonstrated effective in patients with Spondylarthritis (SpA). The lack of efficacy and adverse events (1) have been reported as the most common reasons for the discontinuation of these drugs. In Rheumatoid Arthritis, the immunogenicity has been proved to be an influential factor in the survival of treatment, but this has not been proved in SpA.
Objectives To assess the survival of 3 anti-TNF agents in a cohort of patients with SpA, and to determine if there are differences in the survival of the 3 anti-TNF between patients who develop anti-TNF antibodies and those who do not.
Methods Patients with SpA who started Adalimumab (ADA), Infliximab (IFX) or Etanercept (ETN) as first anti-TNF treatment between 2001–2015 were included. Diagnoses were: Ankylosing Spondylitis (55.5%), Non Radiographic Axial SpA (20%), SpA associated with inflammatory bowel disease (5.9%) and Psoriatic SpA (18.6%). Patients with only peripheral involvement were excluded. Clinical and demographic data were collected, and in the case of ADA and IFX, the presence or absence of anti-drug antibodies were identified. No anti-ETN antibodies were identified. The reasons for drug discontinuation were classified as adverse event, administration reaction, primary inefficacy, secondary inefficacy, recovery and other (this included pregnancy, malignancies, etc). The event was defined as drug discontinuation due to only the first 4 reasons. Cumulative incidence through competitive risk was performed to compare drug survival.
Results Of the 220 patiens studied, 58.6% were men, with a mean age of 43.5±12.4 years. Out of them, 38.6% (85) started treatment with IFX, 30% (66) with ADA, and 31.4% (69) with ETN. No statistically significant difference (p=0.3) was found in the survival of the 3 anti-TNF: IFX had a probability of drug discontinuation of 32.9% at 5 years, compared to 35.5% of ADA and versus 31.8% of ETN. The most common reasons for discontinuing treatment were: Primary inefficacy for IFX (22.4%), primary and secondary inefficacy for ADA (13.6% each), and others (pregnancy, etc) for ETN (26.1%).
30.6% of patients treated with IFX developed anti-IFX antibodies (AIA). Anti-ADA antibodies (AAA) were observed in 22.7% of 66 patients who received ADA. In both drugs, the drug survival was lower in patients who developed anti-TNF antibodies, but this difference was statistically significant only in the group of IFX:
When survival was analyzed by subgroups of patients treated with IFX and ADA who had not developed antibodies compared with ETN, no statistically significant difference was found (p=0.5).
Conclusions In our cohort, the three anti-TNF showed a similar survival. However, and particularly in the case of IFX, the development of anti-drug antibodies proved to be an influential factor in the survival of treatment.
Rosales-Alexander et al. Drug survival of anti-tumour necrosis factor a therapy in spondyloarthropathies: results from the Spanish emAR II study. Rheumatology (Oxford). 2015 Aug;54(8):1459–63
Disclosure of Interest S. García-Carazo Grant/research support from: This work was funded by unrestricted grant from PFIZER, C. Plasencia: None declared, D. Pascual-Salcedo: None declared, D. Peiteado: None declared, G. Bonilla: None declared, L. Nuño: None declared, A. Villalba: None declared, M. Díaz: None declared, F. Arribas: None declared, A. Balsa: None declared