Rituximab treatment of the anti-synthetase syndrome—a retrospective case series

Objective. Interstitial lung disease (ILD) is the major determinant of morbidity and mortality in the anti-synthetase syndrome (ASS). Here we have retrospectively assessed 11 ASS patients with ILD treated with the anti-CD20 mAB rituximab at our tertiary referral hospital. Methods. Data on clinical and laboratory parameters, lung imaging by high-resolution CT thorax and pulmonary function tests were collected from patient examinations done up to 6 months before rituximab was initiated, and at 3 and 6 months post-treatment. Results. All the 11 ASS patients had severe and progressive ILD and most of them had previously failed on cyclophosphamide and/or other immuno-modulating agents. Rituximab appeared to stabilize and/or improve the ILD in 7 of 11 ASS patients during the first 6 months after treatment. The rituximab treatment appeared to decrease the serum level of anti-Jo-1 antibodies, but the decrease was most often modest. One patient developed a fatal infection 3 months after the last infusion with rituximab. In the other ASS patients, the treatment was well tolerated. Conclusions. This retrospective case series indicates a short-term beneficial effect of rituximab in ASS. Prospective, controlled studies are needed to validate this finding and further assess safety issues.