Haploidentical transplantation using low-dose alemtuzumab: Comparison with haploidentical transplantation using low-dose thymoglobulin

Objectives: To establish the optimal strategy for haploidentical hematopoietic stem cell transplantation (HSCT). Methods: We performed a prospective study on haploidentical HSCT using low-dose alemtuzumab. Alemtuzumab was added at 0.25 mg/kg for 2 days. The primary outcome measure was the survival rate with the engraftment of donor cells and without grade III-IV acute graft-vs-host disease (GVHD) at 60 days after transplantation. Results: Fourteen adult patients with advanced hematological disease were enrolled. The primary outcome measure was achieved in 86% of the patients. Six patients experienced relapse/progression. Non-relapse death was observed in three patients, and all of them had a history of previous allogeneic HSCT. Overall survival and progression-free survival rates at 1 year were 51% and 43%, respectively. Four patients were suspected to have herpes simplex virus infection and three had aseptic meningitis under the use of acyclovir at 200 mg. There were no deaths due to viral infection. Compared to those who underwent haploidentical HSCT using thymoglobulin, patients with alemtuzumab showed a slower recovery of CD8 ⁺ T-cells and lower incidences of GVHD and EB virus reactivation. Conclusions: Haploidentical HSCT using low-dose alemtuzumab can be performed safely. We need to overcome the high relapse/progression rate in non-remission patients.