Allogeneic Blood Cell Transplantation Without Posttransplant Colony-Stimulating Factors in Patients with Hematopoietic Neoplasm: A Phase II Study

Purpose: There is limited experience with allogeneic blood cell transplantation (BCT). In an earlier pilot study, the combination of bone marrow and blood did not produce severe acute graft-versus-host disease (GVHD). We now report the results of a phase II study using blood stem cells alone in 19 patients. Patients and Methods: The median age was 40 years. All patients had hematopoietic malignancies and received transplants from HLA-identical sibling donors. GVHD prophylaxis consisted of cyclosporine plus prednisone. Posttransplant colony-stimulating factors were not administered. Donors were mobilized with subcutaneous granulocyte colony-stimulating factor (G-CSF; 16 μg/ kg/d) for 5 days. Apheresis was performed on 2 consecutive days. Results: The median cell content of the two apheresis was 11.9 × 10⁸ WBC/kg, 3.2 × 10⁸ CD3/kg, and 8.3 × 10⁶ CD34/kg. The median time to achieve an absolute neutrophil count (ANC) ≥ 500/μL was 13 days, and 14 days to a platelet count ≥ 50,000/μL. All patients engrafted. Platelet recovery was faster than in marrow historic control groups. Blood cells in all tested cases contained more than 95% donor cells on day 30. The actuarial incidence of acute GVHD was 37%, and 13% for grade II-IV GVHD. Limited, corticosteroid responsive, chronic GVHD developed in 33% of assessable patients. At a median follow-up of 192 days, actuarial survival was 75%. Conclusion: Transplantation of a high number of stem cells may lead to rapid engraftment without the use of posttransplant colony-stimulating factors. GVHD does not appear to be more severe than in similarly treated patients undergoing bone marrow transplantation. For allogeneic transplantation, mobilized blood cell collections are an alternative to bone marrow collections.