Background Safety and efficacy profiles, as well as pharmacokinetics of infliximab biosimilar (INB) have been proven equivalent to those of innovator infliximab (INX) in randomized clinical trials in patients with rheumatoid arthritis (RA) and ankylosing spondylitis (SPA). However, reports concerning experience of the use of INB in a real world setting are sparse.
Objectives To report clinical experience of the use of INB in patients with rheumatic diseases who were switched from INX to INB.
Methods INX treatment of 39 patients was switched to INB. Patients' symptom level and disease activity were available in the clinical database for pain, fatigue, patient global health (PtGlobal) and disease activity (PtAct), and Doctor global assessment of activity (DrGlob) on 0-100mm VAS, HAQ on 0-3, ESR and CRP. Time-dependent area under the curve (AUC) was computed to each variable for time elapsed before biologic treatment, during INX, and during INB treatments, including data from 100, 785, and 157 visits, respectively. Repeated measures were analyzed using generalized estimating equations (GEE) models with an unstructured correlation structure.
Results Cohort. All 39 patients [mean (SD) age 53 (11), 17F, 22M] who were >25years old and received INX to a rheumatic disease in a single clinic were switched to INB after a mean (SD) of 4.1 (2.3) years of INX treatment. Diagnoses of the patients included RA in 15, SPA/axial spondylarthritis 14, psoriatic arthritis 7, juvenile RA 2, and chronic reactive arthritis in 1 patients. Concomitant anti rheumatic drugs (cDMARDs) included methotrexate in 31 patients [p.o. in 24 and s.c. in 7 patients with a median (range) dose of 20mg (5-25mg)]. Other 8 patients took: 1 aza, 1 hcq, and 3 ssz, and 3 had no cDMARD. Two patients took Prednisolon 5mg/day and five patients 2.5mg/day. Blood tests for though INX levels and anti-INX antibodies were taken in the morning before the first INB infusion - results were not available at the 1st INB administration. Clinical experience. Analyses were performed at a median (range) of 11 (7.5 to 13) months after the 1st administration of INB. No difficulties were found in infusion procedure and handling of INB. Patients' symptom level and disease activity on AUC were similar during INX and INB, and lower compared to values before biologic therapies (Table). Eleven patients (28.2%) discontinued INB: in 3 patients, INX-antibodies were found (test taken before the 1st INB infusion) and therefore INB was discontinued after results were available. Latent tuberculosis activated in one patient after he received two INB infusions and had received INX for 12 months before switch – causality to INX/INB was obvious. One patient was diagnosed with neurofibromatosis after two INB infusions and had received INX for almost 5 years before switch; causality to INX/INB remains open. Six patients discontinued INB for subjective reasons without objective deterioration of disease, in whom a nocebo effect cannot be ruled out (INB perceived as “a cheap copy” of INX).
Conclusions Effectiveness of INB appeared similar to INX over a median of 11 months in patients who switched from INX to INB. No immediate safety signals were observed. Larger clinical cohorts and longer follow-up are needed to confirm safety of INB.
Disclosure of Interest T. Sokka Grant/research support from: Hospira, H. Kautiainen: None declared