Platelet and Red Blood Cell (RBC) Transfusion Requirements of Nonmyeloablative (NM) HLA-Matched Related and Unrelated Donor Hematopoietic Cell Transplantation (HCT): Influence of Genetic Disparity and ABO-Incompatibility.
Authors: Wang Zejing , Schoch Gary , Leisenring Wendy M. , Sandmaier Brenda M. , Maloney David G. , Storb Rainer F. 
Published: October 2019

Abstract
NM-HCT makes use of graft-versus-tumor effects and has been applied to treat pts with hematological malignancies who were ineligible for conventional myeloablative (M)-HCT. The current study retrospectively analyzed platelet and RBC transfusion requirements within the first 100 days after HCT in 365 consecutive pts given NM- HCT from HLA-matched related (MRD; n=187) or unrelated donors (URD; n=178) between December 1997 and January 2005. Diagnoses included NHL and HD (29.5%), MM (19.4%), acute leukemias (20%), chronic leukemias (14.8%) and others (16.3%). Pts’ age ranged from 9 months to 74.5 (median 50.1) years. We also asked whether ABO incompatibility increased transfusion requirements in NM recipients, and whether there were differences in transfusion requirements between related and unrelated recipients within the subgroup of ABO-mismatched recipients. Further, overall transfusion requirements were compared to those among 1430 concurrent HLA-matched recipients given M-HCT. Among NM recipients, a higher percentage of unrelated recipients required transfusions than of related recipients (48% vs.25% for platelets p<0.0001, and 87% vs.68% for RBC p<0.0001). Unrelated recipients were also given more daily platelet and RBC transfusion units compared to related recipients (p<0.0001). Major and bi-directional ABO-mismatched recipients had increased requirements for both platelet and RBC transfusions compared to either ABO-matched or minor ABO-mismatched recipients (p=0.0394 and 0.0009 for platelets and RBC, respectively). Within the ABO-mismatched subpopulation, a higher percentage of unrelated recipients received transfusions, and had greater number of daily RBC transfusion requirements compared with related recipients (median of 0.09 versus 0.04, respectively; p=0.039), while platelet transfusion requirements were comparable. Finally, 36% and 77% of NM recipients respectively received platelet and RBC transfusions, compared to 99% and 94% of M recipients respectively (p<0.0001). In conclusion, our data showed that the NM regimen reduced the requirements for platelet and RBC transfusions compared to M regimens. ABO-incompatibility between donors and recipients adversely affected transfusion requirements. Unrelated recipients experienced more profound pancytopenias, possibly owing to greater non-HLA disparities, resulting in greater transfusion requirements.
Transfusion requirements during first 100 days after HCT % of pts requiring platelets transfusions Daily units (Median) p % of pts requiring RBC transfusions Daily units (Median) p Conditioning Nonmyeloablative 36 0 77 0.052 Myeloablative 99 0.420 <0.0001 94 0.100 <0.0001 Nonmyeloablative     related 25 0 68 0.040     unrelated 48 0 <0.0001 87 0.080 <0.0001 Nonmyeloablative     ABO-matched 33 0 72 0.040     Major and bidirectional ABO-mismatched 48 0 0.0394 88 0.100 0.0009     ABO-minor mismatched 34 0 80 0.060 Nomyeloablative ABO-mismatched     related 33 0 78 0.040     unrelated 47 0 0.121 88 0.090 0.039