Reduced-Intensity Conditioning Regimen without Total Body Irradiation undergoing Umbilical Cord Blood Transplantation (non-TBI-RI-UCBT) Induces Successful Engraftment in Adult Patients with Advanced Hematological Malignancies.

Purpose: In a phase I study to evaluate the feasibility and safety of non-TBI-RI-UCBT in patients with advanced hematological malignancies, who were ineligible for conventional allogeneic hematopoietic stem cell transplantation.

Patients and Methods: We treated a total of 6 patients (2 Hodgkin disease, 3 Follicular Lymphoma, 1 MDS overt leukemia). There were 4 female and 2 male, with a median age of 52.5 (46–62) years old. At the transplantation, all patients were in progressive disease (high-risk). Two patients with lymphoma had failed one or more preceding autologous transplants and a patient with overt leukemia had failed an allogeneic transplant. Backbone agent in the conditioning regimen was fludarabine, in combination with melphalan (n=4), or melphalan and thiotepa (n=2). Graft-versus-host disease (GVHD) prophylaxis incorporated cyclosporine alone (n=3), or FK506 alone (n=3). All of the patients received 4 of 6 HLA -antigen-matched umbilical cord blood transplantation. The median number of infused total nucleated cell dose and CD34 plus cell dose before freezing were 3.18 x 10⁷ (2.77–4.7) /kg and 0,85 x 10⁵ (0.57–1.91) /kg, respectively.

Results: All of the patients achieved primary neutrophil engraftment. The median time to reach 0.5 x 10⁹/L neutrophils was 24 (13–31) days. Platelet counts above 20 x 10⁹/L were achieved by 3 patients on median day of 40 (39–45) days. The median time to complete donor chimerism was 26.5 (16–35) days. Acute GVHD occurred in 2 of the 6 patients (grade I/II in 2). Chronic GVHD developed in none of the evaluable patients. Two of the 6 patients developed noninfectious fever before neutrophil engraftment. Three patients died of TRM (1 pneumonia, 1 thrombotic microangiopathy, 1 acute heart failure), and the other 2 patients died due to disease progression. At a median follow-up of 65.5 days (33–78), one of the 6 patients is currently alive in CR.

Conclusion: Although this study is preliminary with a small number of patients and short follow-up, our findings demonstrated the successful engraftment of non-TBI-RI-UCBT for adult patients with relapsed/refractory hematological malignancies. Prospective study to further evaluate the efficacy of non-TBI-RI-UCBT for hematological malignancies is warranted.