Methods, Two cohorts of 4 patients who fulfilled criteria for severe, active, treatment-resistant RA were recruited into a dose-escalation study of cyclophosphamide (CYC) (100 mg/kg or 200 mg/kg) followed by unmanipulated peripheral blood stem cell rescue. Patient treatment was managed according to a standard supportive care protocol. Disease-modifying drugs were discontinued before treatment, but corticosteroids were maintained and later tapered where possible. Patients' conditions were assessed using World Health Organization toxicity criteria and standard parameters for rheumatic disease.

Results. Dose-dependent differences in hematologic toxicity were observed between cohorts 1 and 2, although toxicity was similar for other systems and was most significant in the gastrointestinal system. Patients in cohort 1 had only transient responses to therapy, lasting 2-3 months. Substantial improvements were sustained beyond 17-19 months in cohort 2, including steroid-independent disease remission for 1 patient, although the procedure did not completely abolish disease activity.

Conclusion, High-dose CYC and unmanipulated autologous blood stem cell rescue has acceptable dose-dependent toxicity in severe, treatment-resistant RA, and 200 mg/kg of CYC induces substantial clinical responses. Refinement of this intensive approach might include further intensification of the preparation regimen, graft manipulation, and posttransplant immunomodulation.