Biological agents in the management of Felty's syndrome: a systematic review.

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/mm(3)) 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.