FRI0070 Prevalence and Evolution of Monoclonal Gammapathy of Undetermined Significance in Patients with Rheumatoid Arthritis Patients Treated with Abatacept: Data from the ORA Registry. (9th June 2015) - Salliot, C.
Abstract : Background: Monoclonal gammapathy of undetermined significance (MGUS) is premalignant plasma-cell disorder. Its prevalence is about 3.2% of the general population older than 50 years. In patients with rheumatoid Arthritis (RA), little is known about the prevalence of MGUS and its evolution under biologics. Objectives: To assess the prevalence of MGUS in longstanding RA, the characteristics of patients with MGUS, and the evolution of MGUS under abatacept. Methods: ORA (Orencia and Rheumatoid arthritis) is a French prospective 7-year registry which included 1017 RA patients at abatacept initiation. Data on disease characteristics, biologic abnormalities including the presence of a monoclonal gammapathy, and the occurrence of severe adverse events, including cancers such as lymphomas, myelomas are collected at enrollment and every 6 months. Results: Among the 1017 RA patients included in ORA registry, 38 had a MGUS (3.7%). Baseline disease characteristics (gender, age, RA duration, positivity for anti-CCP and rheumatoid factors, DAS28ESR) were not significantly different between patients with or without MGUS. In RA patients with MGUS, mean age and RA duration were 58.2±13.6 and 13.8±9.5 years, respectively. 76.3% were women 52.6% and 55.2% had anti-cyclic citrullinated peptide (anti-CCP) and rheumatoid factors (RF), respectively. 92.1% of patients previously received biological treatments (with a mean of 2.5±1.3 biologics): 89.5% previously received anti-TNFs and 42.1% receive rituximab As concomitant treatment, 47.3% received methotrexate and 84.2% corticosteroids. During the follow-up of 1.50±1.10 years, no significant change in the blood level of the monoclonal component was observed. Two patients developed a multiple myeloma;. For the first patient, Immunoglobulin G Kappa stade 3 myeloma was diagnosed only 83 days after abatacept initiation. For the second patient, immunoglobuline G myeloma stade 1 was diagnosed 1 year after abatacept initiation. No lymphoma nor amyloidosis occurred. Conclusions: The prevalence of MGUS in this population with longstanding RA was similar to that observed in the general population (∼3%). No significant effect of abatacept on the blood level of the monoclonal component was observed after 2 years of prospective follow-up. Although no signal has been observed, a longer follow-up is needed to evaluate the effect of abatacept on the risk of malignant transformation of MGUS. References: Kyle RA et al. Prevalence of MGUS, N Engl J Med 2006;354:1362-9. Smale SW et al. Scand J Rheumatol. 2007;36: 405-6. Disclosure of Interest: None declared