Outcome of Adult Patients Diagnosed with Aplastic Anemia That Underwent Allogeneic Stem Cell Transplantation: A Single Institution Experience

Abstract

Background This study is a single center experience of alloHSCT for adult patients with aplastic anemia (AA) over 13 years, using two different conditioning regimens. Methods Fifty-eight consecutive patients were included in the study. 51 (88%) received Alemtuzumab (Alem) (50-60mg) and 7 (12%) rabbit anti-thymoglobulin (ATG) (4.5 mg/kg) as part as the conditioning. Median follow up was 5 years (range 0-12). Last follow-up was July 2018. Overall survival (OS) was calculated with Kaplan-Meier product method and the impact of variables in OS was assessed using Log-rank test. Multivariable test could not be done due to low number of event/patients. Results Patient information is in Table 1. Median time to neutrophil and platelet engraftment was 18 days (range 10-100) and 17 days (4-100). Eight (14%) patients had graft failure (GF): 3 primary/5 secondary and 3 died due to GF. Risk factors and outcomes for OS are in Table 2 and Figure 1. 23 (40%) patients had CMV reactivation, 13 (22%) had EBV-reactivation, and 5 (9%) developed post-transplant lymphoproliferative disorder. Cumulative incidence of grade II-IV acute GVHD at day 100 was 14% (95% CI 4-23) and of chronic GVHD at 1 year was 7% (95% CI 0-16%) (Figure 2-3). Conclusion Alem treated patients may have a better OS than ATG treated cases, but any conclusions are limited by low number of ATG recipients. The OS was not different between graft source: bone marrow (BM) vs peripheral blood stem cells (PBSC); nor between the MRD and MUD transplants, despite more frequent use of PBSC and prior use of immunosuppressive therapy (IST) in the MUD group. Larger studies are required to determine if Alem is superior to ATG in transplant for AA.