Cyclophosphamide plus granulocyte colony stimulating factor (G-CSF) is more effective than G-CSF alone in mobilizing hemopoietic progenitor cells in severe, refractory rheumatoid arthritis.

Autologous hematopoietic stem cell transplantation (AHSCT) has been proposed as a treatment for severe, refractory rheumatoid arthritis (RA).1 Although it needs to be clarified by controlled studies in this setting, AHSCT with ex vivo T-cell depletion might be more effective than an unmanipulated graft reducing the reinfusion of autoreactive T-cells.2 Peripheral blood stem cells are now replacing bone marrow cells as a source of hematopoietic progenitors. Release of a large number of hematopoietic stem cells as required for engraftment can be obtained by granulocyte colony-stimulating factor (G-CSF) either alone or in combination with chemotherapy.1,3 In patients with malignancies, mobilization with cyclophosphamide and G-CSF allows the collection of a larger number of stem cells than G-CSF alone.3 This may be useful when T-cell depletion is planned, as ex vivo graft manipulation is associated with a reduction of stem cell content.4 Previous studies have looked at the combination of cyclophosphamide plus G-CSF in RA,1,5 however direct comparisons between combination treatment and G-CSF alone have not been formally undertaken. After signing informed consent, seven patients with severe RA refractory to conventional therapy were enrolled in a clinical trial approved by the ethical committee of the Maugeri Foundation Institute for Clinical Research. Bone marrow examination was normal in all cases; one patient (#6) had developed stage I non-Hodgkin’s lymphoma (treated with surgery and radiotherapy) 3 years before this study. Three patients (#1-3) received I.V. cyclophosphamide (4 g/m2) followed by lenograstim 10 μg/kg/d starting from day 4 until stem cell collection. Four patients (#47), matched for sex, age, disease activity and duration, received lenograstim 10 μg/kg/d until stem cell collection. CD34+ cell count in the peripheral blood was monitored daily by Facscalibur (Becton Dickinson Immunocytometry Systems, San José, CA, USA); when CD34+ cells exceeded 20/μL, stem cell collection was performed by a Cobe Spectra cell separator (Cobe, Denver, CO, USA). Positive immunoselection was performed using a Isolex 300i cell separator device (Baxter Health Care, Deerfield, IL, USA). Since the number of CD34+ cells required for safe hematopoietic recovery is ≥2.5×106/kg and considering that immunoselection may cause a loss of hematopoietic progenitors, this procedure was performed only in case of harvesting ≥5×106 CD34+ cells/kg. An aliquot of the CD34+ cells exceeding 5×106/kg was stored unselected as a back-up graft. Stem cell mobilization was highly effective in patients receiving cyclophosphamide plus growth factor as compared to G-CSF alone, so that CD34+ cell immunoselection could be performed only in the former patients (Table 1). No patient experienced flares of the disease; neutropenic fever was observed in patient #3 but no infections or bleeding were documented and no patient required blood transfusions. Patients who received cyclophosphamide had complete hair loss lasting 3 months. The clinical outcomes of RA following mobilization are shown in Table 2 according to the core set criteria of the American College of Rheumatology.6 The number of CD34+ cells in the peripheral blood of RA Table 1. Stem cell mobilization, collection and immunoselection in seven patients with severe, refractory rheumatoid arthritis after cyclophosphamide plus G-CSF (patients #1-3) or G-CSF alone (patients #4-7). CD34+ cell positive selection to obtain partial T-cell depletion was performed only in case of harvesting at least 5x106 CD34+ cells/kg.