Allogeneic Hematopoietic Cell Transplantation for Severe Idiopathic Aplastic Anemia Older Than 40y

Upfront allogeneic hematopoietic cell transplantation (alloHCT) as first line therapy for older than 40 or 50 years is not usually recommended for severe aplastic anemia patients even though there are suitable matched sibling donors because they usually have poor outcomes after alloHCT. Therefore, first line immune suppression therapy (IST) is recommended. However, current outstanding alloHCT outcome can make it possible to try upfront alloHCT even in older AA patients. The purpose of this retrospective study is to determine the transplantation-related results in AA patients older than 40 years. This study collected data retrospectively for older AA patients. Congenital bone marrow failure was excluded from this study. alloHCT was divided as upfront and second alloHCT according to prior IST.

Total 129 patients were enrolled in this study from 2001 to 2017. Age at diagnosis and at alloHCT were 25 to 63 (median 48.0) years and 40.3-64.9 (median 49.1) years, respectively. Median time from diagnosis to alloHCT was 5.2 (range, 1-234.1) months. Upfront and second alloHCT were 42 and 87 patients, respectively. Upfront alloHCT received more stem cells from related donors, more BM stem cells and more fludarabine conditioning compared with second alloHCT (83.3% vs. 58.6%, p=0.005; 52.4% vs. 74.7%, p=0.011; 52.4% vs. 30.2%, p=0.015, respectively). However, ABO mismatching (p=0.747), TBI conditioning (p=0.547), cyclophosphamide conditioning (p=0.114), ATG conditioning (p=0.483) were similar between upfront and second alloHCT. Any engraftment failure, neutrophil engraftment failure and platelet engraftment failure were similar between upfront and second alloHCT (28.6% vs. 28.7%, p=0.985; 19.0% vs. 18.4%, p=0.928; 19.0% vs. 34.5%, p=0.072). Hepatic SOS, acute GvHD and chronic GvHD were also similar between upfront and second alloHCT (4.8% vs. 5.7%, p=0.817; 28.6% vs. 36.5%, p=0.376; 19.0% vs. 19.5%, p=0.947). Survival rates at 1Y, 2Y, 3Y and 5Y were 90.7, 82.2, 73.5 and 64.3%, respectively. Survival rates at 5 years in upfront and second alloHCT were 76.2 and 54.1%, respectively (p=0.059). Survival rates at 5 years (5YSR) in age 40-50y, 50-60y, and older than 60y were 64.1, 62.4 and 50.0%, respectively (p=0.349). alloHCT from matched related donor or other donors had similar survival rates (p=0.404). However, upfront alloHCT showed superior survival rate (5YSR 76.5% vs. 53.2%, p=0.114) without statistical significance compared with second alloHCT even in matched related donor subgroup. This trend is similar in alternative donor subgroup (5YSR 75.0% in upfront alloHCT vs. 54.9% in second alloHCT, p=0.459).

alloHCT in older AA showed promising results even in patient older than 60 years although upfront alloHCT showed marginal statistical superiority. In conclusion, upfront alloHCT in older AA needs further confirmation by prospective studies.