Objective To review and summarize the information available on the effectiveness and safety of biological therapies in refractory Felty's syndrome (FS). Methods We describe a case of FS with severe ...neutropenia and recurrent bacterial infections unresponsive to disease-modifying antirheumatic drug treatment and long-term administration with granulocyte colony-stimulating factor, in which treatment with rituximab (RTX) was useful and resulted in a sustained neutrophil response. Current evidence on the use of biological therapies in FS is also analyzed through a systematic review of the English-language literature, based on a PubMed search. Results Available data on the use of biological therapies in refractory FS are based only on several case reports and are limited to the use of RTX and some anti-tumor necrosis factor α agents (etanercept, infliximab, and adalimumab). Including the case described here, data are available on 8 patients treated with RTX. A sustained increase in the absolute neutrophil count (>1500/mm3 ) was observed in 62.5% (5/8) of these patients after 1 cycle of treatment. In most of them, the hematological response was accompanied by a parallel improvement in biological markers of inflammation and other clinical manifestations of FS (arthritis, recurrent infections, systemic symptoms, etc). After a median follow-up of 9 months (range, 6-14), only 1 of these patients relapsed and neutropenia reappeared; in this patient, retreatment was rapidly effective. No significant adverse events related to RTX therapy were reported. Experience with anti-tumor necrosis factor agents is limited to 6 patients, none of whom presented any sustained increase in neutrophil count. Conclusions Although it is not yet possible to make definite recommendations, the global analysis of all cases reported to date only supports the use of RTX as a second-line therapy in patients with refractory FS.
