Long-Term Survival after Reduced Intensity Conditioning (RIC) Allogeneic Stem Cell Transplantation in AML-Patients Is Consistently Sustained and Influenced by Donor Type Selection.

A total of 46 patients (24 female, 22 male) with acute myeloid leukemia (AML) received RIC allogeneic blood stem cell transplants from either fully HLA-compatible family donors (n=14) or unrelated HLA-compatible donors (n=32) between 3/1999 and 3/2007. The unselected consecutive single centre study patients (median age: 52 years, range: 22–64) were at high risk for treatment-related complications (older age, previous infectious complications, impaired organ function). 67% (n=31) of the cohort were not in first remisson but in an advanced status of AML. All patients received 30 mg·m−2 Fludarabine i.v. day −10 to −5, Busulfan 4mg·kg−1 orally day −5 to −4, and 10 mg·kg−1 i.v. Antithymocyteglobulin (ATG-Fresenius®) day −4 to −1 as RIC prior to allogeneic stem cell transplantation. A median of unselected 6.8 x 106 CD-34 positive stem cells (range: 1.9–14.3) were given. GvHD-prophylaxis consisted of Cyclosporin 3mg·kg−1 continuous infusion in case of 10/10 HLA compatibility donor situation (n=34), with the addition of mycophenolate mofetil 2gr. i.v. primarily starting from day +10 in one antigen mismatched HLA-unrelated donor situation (n=12). Nine patients (19.6%) died of therapy related mortality, due to GvHD (n=3), infections (n=4), or both (n=2). Relapses occurred in 18 patients (39%), in five patients even more than one year after transplantation. The median observation time of the study group was 19 months (range: 3–101), the product-limit estimates (Kaplan-Meier) of overall survival (OS) at 36 months were 0.48 (±0.08), of event-free survival (EFS) 0.44 (±0.08), respectively. Figure Figure Disease-status (remisson vs. advanced) failed to have a significant impact in OS or EFS, whereas donor status (related vs. unrelated) resulted in OS at 24 months 0.76 (±0.12) for related donors and 0.4 (±0.09) for unrelated donors (p=0.017, log-rank test). RIC with Fludarabine/Busulfan/ATG prior to allogeneic stem cell transplantation results in a consistently sustained long-term outcome for this otherwise adverse patient subgroup, favouring family-matched donor selection.