Intensified-dose (4 gm/m2) cyclophosphamide and granulocyte colony-stimulating factor administration for hematopoietic stem cell mobilization in refractory rheumatoid arthritis.

OBJECTIVE: To evaluate the feasibility, safety, and efficacy of intensified-dose cyclophosphamide (ID-CYC), followed by granulocyte colony-stimulating factor (G-CSF) administration for collection of peripheral blood hematopoietic stem cells (HSC), for patients with severe, refractory rheumatoid arthritis (RA). METHODS: Four patients with severe refractory RA were enrolled in this open study. They received a single infusion of CYC (4 gm/m2) at day 0 followed by G-CSF (5 microg/kg/day) from day 6 until the last day of leukapheresis (performed at the time of hematopoietic recovery) to harvest peripheral blood HSC. Patients were monitored for disease activity, adverse effects, and hematopoietic reconstitution following this procedure. RESULTS: For all patients, administration of ID-CYC induced an early, dramatic improvement of disease activity. Long-term followup indicates that partial disease relapse was observed for all patients. No adverse effect was directly attributable to the treatment procedure. For most patients, HSC collection was sufficient to provide a graft enriched in CD34+ cells by positive selection as well as an unselected rescue graft. CONCLUSION: Patients with severe, refractory RA can benefit from ID-CYC. This procedure, followed by G-CSF administration, appears safe and technically suitable. In addition, it allows immediate improvement of RA activity that can occasionally persist beyond 6 months.