#OA1-AM25-TU-15 - Duffy-Null Status and Delayed Neutrophil Engraftment in Autologous Hematopoietic Transplantation: A Call for Awareness

Duffy-null–associated neutropenia (DANC), characterized by constitutionally low absolute neutrophil counts (ANC) in individuals of African descent, is now recognized as a benign hematologic phenotype. However, prevailing definitions of engraftment do not account for this genetic variation, potentially leading to inappropriate risk stratification and improper diagnoses and potential exposure to medications (e.g. G-CSF). 

Study

Design/Methods:

This study was performed as part of a quality improvement initiative evaluating engraftment assessment.  Engraftment kinetics in Duffy-null patients (n=20) who underwent autologous hematopoietic cell transplantation (AHCT) at a large tertiary-care cancer center were retrospectively analyzed.  Days to absolute neutrophil count (ANC) and platelet count engraftment were the markers analyzed; for the purposes of this study platelet count was used as a control marker that should be unaffected by patient Duffy status.  Engraftment was defined as ANC ≥0.5×10⁹/L and platelet count ≥20×10⁹/L for three consecutive days without transfusion.  Time to engraftment was compared to institutional averages across all patients undergoing AHCT.

Results/Findings:

• Mean time to neutrophil engraftment in Duffy-null patients was 12.8 days (SD: 5.08), compared to 11 days in the general AHCT population.


• Mean platelet engraftment time was 21.0 days (SD: 4.34), identical to the overall cohort.

These findings are consistent with prior work (Avigan et al., Blood Advances, 2025), which demonstrated delayed ANC recovery in Duffy-null patients post–CAR-T therapy without adverse clinical outcomes. Additionally, our results mirror conclusions from large-scale AHCT cohorts (Lutfi et al., Hematol Oncol Stem Cell Ther, 2020), though those lacked genotype-specific stratification.

Conclusions:

Duffy-null patients exhibit a modest, non-harmful delay in neutrophil engraftment post-AHCT. Although these patients run similar risk for post-transplantation complications of neutropenia, they do not appear to be at greater risk based upon the slower ANC recovery. Given this physiologic variation, rigid adherence to conventional ANC-based criteria may unjustifiably stratify this population into a higher-risk category. Our data support further evaluation of genotype-aware engraftment definitions and reinforce the need for widespread Duffy antigen testing and education, as championed by the ASH DANC Project.  Additional investigation(s) with a larger duffy-null patient population is warranted.