Infliximab therapy for patients with active and refractory spondyloarthropathies at the dose of 3 mg/kg - A 20-month open treatment

Background: Infliximab at the dose of 5 mg/kg per infusion has been shown effective for the treatment of active spondyloarthropathies. It is not clear if the 5 mg/kg is required in most patients. Objective: To evaluate the long-term efficacy and safety of infliximab at the lower dose of 3 mg/kg in patients with active and refractory ankylosing spondylitis (AS) and psoriatic arthritis (PsA). Methods: Thirty patients were enrolled in a 78-week, single-center, prospective, open-label pilot study, including 16 patients with severe and active AS and 14 patients with active and refractory PsA. Infliximab (3 mg/kg, in combination with a stable dose of methotrexate was administered intravenously at 0, 2 and 6 weeks, and q8 weeks thereafter (schedule-A) and the improvement of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI; for AS patients) and Patient Global Assessment of Disease Activity (PDA; for PsA patients) was monitored at baseline and at every visit (primary variables). Patients who did not respond sufficiently at 14 weeks, as well as patients who relapsed at any time during follow-up, received infliximab every 4 weeks (treatment schedule-B). Three different statistical approaches (per-protocol, last observation carried forward and by intention-to-treat) were applied. Results: Ten patients discontinued treatment for various reasons, including 3 (10.0%) because of allergic reactions. Twenty patients (66.7%, 9 with AS and 11 with PsA) had completed 78 weeks of treatment (schedule-A, 11 patients; schedule-B, 9 patients). Of these patients, 18 (90.0%) showed optimal response (improvement greater than or equal to50%), including 13 (65.0%) with improvement greater than or equal to70%. ASsessments in AS (ASAS) 50% was attained by 7/9 AS patients (77.8%). At 78 weeks of treatment, statistically significant improvement of indices of disease activity, function and quality of life was observed by all statistical approaches applied. Conclusions: Infliximab at 3 mg/kg every 8 weeks or, if needed, every 4 weeks appears to be an effective and rather safe treatment of patients with active and refractory AS and PsA after 78 weeks of treatment.