SAT0205 Real Life Experience Suggests Differential Effects of Rituximab on Refractory Dermatomyositis and Polymyositis
Authors: L. Unger, S. Kampf, K. Lüthke, M. Aringer
Journal: Annals of the Rheumatic Diseases (2013)

<h3>Background</h3> Rituximab has been used for patients with refractory myositis in many centers, including ours. In a large double-blind trial on rituximab in inflammatory myopathies, no significant difference has been found between the two arms, where patients received rituximab at week 0 or week 8 (1). Nevertheless, the authors reporting on this trial argued that the data still suggested a rituximab effect. <h3>Objectives</h3> To investigate objective outcome parameters of off label therapies with rituximab in patients with severe dermatomyositis or polymyositis refractory to standard therapy. <h3>Methods</h3> In a historical prospective way, the charts of all our patients with dermatomyositis or polymyositis who received rituximab were analyzed for glucocorticoid dose, CPK, and lung function tests, where available, as well as for serious adverse events. <h3>Results</h3> A total of 19 patients were identified, one of whom died from aspiration three weeks after the first rituximab infusion. Charts of 18 patients (13 with polymyositis, 5 with dermatomyositis, age 57±18 years (mean±SD), 17 female : 1 male) could be further analyzed. Rituximab was initiated in patients suffering from inflammatory myopathies with myositis (n=12), alveolitis (n=11), or arthritis (n=7) refractory to previous therapies (glucocorticoids in all, methotrexate in 67%, azathioprine in 39%, cyclophosphamide in 50%, intravenous immunoglobulin in 56%). In addition to the fatal aspiration pneumonia, six more severe infections (erysipelas (n=2), respiratory tract infection (n=1), urinary tract infection (n=1), herpes zoster (n=1), unclear focus (n=1)) were seen. One patient developed hypogammaglobulinaemia. Two patients had mild infusion reactions. Under rituximab, prednisolone was reduced from a median of 23.3 (range 7.5 to 523.5) mg q.d. to 8.8 (5.0-30.0) mg q.d. by week 18 (±6) (p=0.0156, Wilcoxon signed rank test) and to 7.5 (2.5-75.0) mg q.d. by week 30 (±6). At the same time, CPK decreased from a median of 10.03 (range 0.55-63.65) µmol/l*s to 3.27 (range 0.96-19.81) µmol/l*s by week 18 (p=0.0024, Wilcoxon signed rank test) and to 1.77 (0.92-8.87) µmol/l*s by week 30. Of 13 patients with elevated CPK, 8 had a decrease by at least 50%. In 8 patients with sufficient documentation of pathological lung function tests, an increase from a baseline 71.4±15.1 % (mean±SD) to 82.7±15.1 % of the expected value was seen at six months (p=0.0183, paired t-test), with 6/8 patients improving their total lung capacity (TLC) over time. Over all, of the 13 polymyositis patients, 9 were seen as responders, and 8/13 anti-synthetase syndrome patients had to be retreated because of flares. In contrast, all 5 dermatomyositis patients responded, and none had to be retreated. <h3>Conclusions</h3> In a real life population of patients with severe, refractory polymyositis or dermatomyositis, objective improvement was seen in the majority of patients with regard to CPK and lung function tests. At the same time, glucocorticoids could be reduced. In contrast to the subgroup with dermatomyositis, where one cycle of rituximab appeared sufficient, patients with anti-synthetase syndromes commonly experienced flares necessitating rituximab re-therapy. <h3>Acknowledgements</h3> Oddis CV et al, Arthritis Rheum 2012 Nov 2 doi 10.1002/art.37754 Epub <h3>Disclosure of Interest</h3> L. Unger: None Declared, S. Kampf: None Declared, K. Lüthke: None Declared, M. Aringer Consultant for: Roche