Ki-Seong Eom, Silvia Park, Sung-Eun Lee, Gi June Min, Jong Hyuk Lee, Byung Sik Cho, Jong Wook Lee, Seung-Hwan Shin, Daehun Kwag, Chang-Ki Min, Seok-Goo Cho, Hee-Je Kim, Seok Lee, Sung-Soo Park, Yoo-Jin Kim, Jae-Ho Yoon, Seung-Ah Yahng, and Tong-Yoon Kim
Despite recent emergence of novel target agents, allogeneic stem cell transplantation is still the favored option for disease control in relapsed patients with acute myeloid leukemia (AML). Allotransplant from alternative donors such as haploidentical donor or cord blood can be done when fully HLA matched donor is not available. As for patients relapsed after the first stem cell transplantation (SCT1), these alternative stem cell sources often become only available options for the second transplantation. However, there has been no report comparing haploidentical stem cell (HIT) and cord blood transplantation (CBT), especially for the second transplantation. We performed a retrospective cohort study on AML patients who relapsed after SCT1 and underwent second allogeneic SCT from either alternative donor at our institution. We identified a total of 50 corresponding patients between January 2008 and February 2021 where 31 HIT and 19 CBT were included, and analyzed SCT outcomes including overall survival (OS), disease free survival (DFS), cumulative incidence of relapse (CIR), non-relapse mortality (NRM) and the incidence of SCT complications with comparing between the 2 groups. Conditioning regimens for HIT and for CBT were as follows: Fludarabine (30mg/m2/day intravenous (IV) for 5 days), busulfan (3.2mg/kg/day IV for 2 days), fractionated total body irradiation (fTBI, 4-8Gy total) and rabbit antithymoglobulin at a dose of 1.25mg/kg/day for four days for in vivo T cell depletion from D-5 to D-2 was given for HIT. G-CSF-mobilized peripheral blood stem cell was used as allograft. Graft-versus-host disease (GVHD) prophylaxis was done with tacrolimus and methotrexate. For CBT, fludarabine (30mg/m2/day IV for 5 days), cytarabine (1.5g/m2 twice daily for 3 days) with fTBI (12Gy). All CBT patients received double cord blood units. GVHD prophylaxis was done with tacrolimus and mycophenolate mofetil. The median follow-up period for survivors was 64.6 months (range 5.3-154.1). The type of SCT1 differed between the two groups; more patients of HIT were the recipient of prior autologous transplantation (41.9%), and 63.2% of CBT had underwent prior HIT (p Overall respective outcomes of HIT and CBT were as follows; 41% and 29% for 2-year OS (p=0.017), 41% and 16% for 2-year DFS (p=0.016), 36% and 36% for 2-year CIR (p=0.91) and 23% and 48% for 2-year NRM (p=0.021). Early NRM within 100 days of SCT2 was more frequent in CBT than HIT although not statistically significant (26.3% vs 9.7%, p=0.23). Median days to neutrophil and platelet engraftment were 12 (range 11-23) and 13 (range 9-38) in HIT, and 29 (range 16-48), 51 (range 27-167) for CBT, respectively (p This is the first report, to the best of our knowledge, to compare outcomes of the second transplantation from alternative donors for relapsed AML patients after SCT1. Our unique T-cell replete HIT using a reduced-toxicity conditioning regimen seems to provide better survival than CBT. Figure 1 Figure 1. Disclosures Lee: Alexion, AstraZeneca Rare Disease: Honoraria, Membership on an entity's Board of Directors or advisory committees. Kim: AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AIMS Biosciense: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; AML-Hub: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; BL & H: Research Funding; BMS & Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Boryung Pharm Co.: Consultancy; Daiichi Sankyo: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Handok: Consultancy, Honoraria; LG Chem: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria; Pintherapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sanofi Genzyme: Honoraria, Speakers Bureau; SL VaxiGen: Consultancy, Honoraria; VigenCell: Consultancy, Honoraria.