P212 The effect of body weight in response to subcutaneous tocilizumab in patients with RA

Abstract

Abstract Background Tocilizumab is an IL-6 receptor humanised monoclonal antibody treatment option in rheumatoid arthritis (RA) who have not responded or are intolerant of disease modifying anti-rheumatic drugs (DMARDs) or other biologics. Tocilizumab was available initially as an intravenous preparation, dosed according to weight, and more recently as a subcutaneous (SC) preparation given at 162mg/weekly irrespective of body weight. Obesity is highly prevalent in RA and there has been concern that starting or switching patients to SC tocilizumab could reduce its effectiveness in those patients with a higher body weight. The objective of the current study is to investigate the relationship between body weight and DAS28 response at 6 months in tocilizumab naïve RA patients starting SC tocilizumab. Methods The study population comprised RA subjects recruited to the BSRBR-RA up to 30/11/2018 commencing SC tocilizumab for the first time. Patients had to be tocilizumab naïve and have at least one six monthly study follow-ups recorded after starting tocilizumab. Baseline characteristics at point of starting tocilizumab are described. Linear regression, fully adjusted for relevant confounders, was used to investigate the relationship between change in DAS28 score from baseline to six months and body weight per ten kilograms (kg), and in a separate analysis, as BMI category. Multiple imputation was used to handle missing data. Results Three hundred and fifteen patients starting SC tocilizumab were eligible for analysis. The median age was 60 years, majority were female, and had median disease duration of 11 years at baseline. Seventy percent had prior biologic exposure. Median weight was 76kg, and the majority of patients were categorised as normal weight (37%) or pre-obesity (31%) according to BMI. Median DAS28 score was 5.5 at start of treatment with median improvement after 6-months of 2.0 units. The fully adjusted linear regression model showed no association between body weight or BMI and change in DAS28 score at six months (Table 1). Conclusion Data from this study show that body weight does not appear to affect initial response to SC tocilizumab. This is reassuring given that patients are likely to be given subcutaneous tocilizumab due to ease of administration and reduced hospital costs. Disclosures R. Davies None. A. Vivekanantham None. M. Lunt None. K. Watson None. K.L. Hyrich None. J. Bluett None.