AB0358 ABATACEPT AS A bDMARD IN STEROID-REFRACTORY POLYMYALGIA RHEUMATICA

Abstract

Background: polymyalgia rheumatica (PMR) is a chronic inflammatory disorder affecting elderly people. Glucocorticoids (GC) are the mainstay of therapy for PMR. Despite this treatment, the disease may relapse or GC dosage cannot be tapered. Methotrexate (MTX) may be helpful in these cases. Blockade of IL-6 has an effective steroid-sparing effect in patients with giant cell arteritis (GCA) and may improve the clinical symptoms of patients with PMR. The pathophysiology of PMR still remains uncertain but there are evidences for a participation of Th1 and Th17 lymphocytes. Recently, blockade of the costimulatory pathway by abatacept (ABA) gave favorable results in GCA. Objective(s): to report our experience (efficacy and safety) of ABA in the treatment of patients with isolated PMR who required longstanding GC and who failed to respond to MTX and/or IL-6 receptor blocking agents. Method(s): a call for observations of all cases of patient with PMR who received at least one dose (SC or IV) of ABA was sent to the members of the French specialist network Club Rhumatismes & Inflammation (CRI: www. cri-net.com)(rheumatologist and internal medicine). Patients must satisfy the EULAR/ACR criteria for PMR and have isolated PMR without associated GCA. Result(s): 4 cases were declared during a 12 months period: 2 men and 2 women; age (median range]): 60.7 50-68] years; disease duration 30 7-48] months; duration of GC treatment before starting ABA: 60 10-72] months. They all required prednisolone with a daily dosage of 14.5 mg 10-20]. Before ABA administration, they all received MTX while 2 patients were treated by IL-6R inhibitor (tocilizumab 6 months and sarilumab 3 months, respectively) without improvement. ABA was given as a monthly infusion (10 mg/kg) in one case and subcutaneously (every week) in 3 cases. ABA treatment duration ranged from 3 to 18 months. Two patients responded to the treatment with a progressive decline of DAS-PMR and GC dosage tapering during a 12 month follow-up, while there was no improvement for the 2 others (Table 1). CRP levels also decreased for one responder. The safety was excellent for all. ABA was still maintained in one responder. Among the non-responders, one patient was switched to tocilizumab and the second still received high GC dosage. Conclusion(s): ABA may be effective in certain PMR patients who were unable to taper GC, with a good safety profile. A randomized controlled trial is required in order to determine its place in the treatment of PMR and to select the appropriate patients who could potentially benefit from this biological agent.