HSCT Conditioning With ATG Is Superior to Historical Conventional Outcomes

Fludarabine, cyclophosphamide, and antithymocyte globulin (ATG) conditioning had superior outcomes versus fludarabine and cyclophosphamide conditioning prior to hematopoietic stem cell transplantation (HSCT) in patients with severe aplastic anemia, according to a 10-year retrospective, single center analysis.

Specifically, conditioning with ATG yielded significantly higher two-year overall survival (OS) and event-free survival (EFS) rates compared with historical data on non-ATG regimens, according to Reem Alasbali, MD, at King Faisal Specialist Hospital and Research Center in Riyadh, Saudi Arabia, who presented the study at the 2024 Tandem Meetings of ASTCT^® and CIMBTR^®.

Data Supports ATG Triplet as Preferred Conditioning Regimen

The analysis included 28 young, fit patients with severe aplastic anemia who underwent matched sibling donor (MSD) allogeneic HSCT from 2013 to 2022. The conditioning regimen was fludarabine 150 mg/m², cyclophosphamide 200 mg/kg, and ATG 2.5 mg/kg, and graft-versus-host disease prophylaxis included methotrexate with either tacrolimus or cyclosporin.

The cohort had a mean age of 25 ±10.2 years, 57.1% of patients had paroxysmal nocturnal hemoglobinuria clones, 25% underwent total body irradiation, and 93% had fully matched sibling donors. The graft source was bone marrow in 60.7% of patients, peripheral blood in 28.6%, and a combination of both in 10.7%.

After a median follow-up time for survivors of 34 months, the two-year rates of OS and EFS were both 100%, whereas the historical data on fludarabine and cyclophosphamide with a median follow-up of 100 months reported rates of 87.8% and 82.9% for two-year OS and EFS, respectively.

“These findings support the continued use of [fludarabine, cyclophosphamide, and ATG] as a preferred conditioning regimen in MSD allogeneic HSCT” for patients with severe aplastic anemia, Dr. Alasbali and colleagues concluded.

Reference

Alasbali R, Fakih RE, Chaudhri N, et al. Favorable outcomes in severe aplastic anemia patients undergoing allo-HSCT with fludarabine, cyclophosphamide, and ATG conditioning. Abstract #208. Presented at the 2024 Tandem Transplantation & Cellular Therapy Meetings of ASTCT^® and CIBMTR^®; February 21-24, 2024; San Antonio, Texas.