Intraprocedural Yield Estimation Using Interim Product CD34 + Concentration Improves the Prediction Accuracy in Allogeneic Peripheral Blood Stem Cell Harvest

Introduction Accurate prediction of final CD34+ cell yield may reduce donor burden by limiting processed blood volume (PBV) during allogeneic peripheral blood stem cell harvest. Methods We retrospectively analyzed 86 procedures in 81 healthy donors. Predictions based on preprocedure peripheral blood CD34+ cell concentration and interim collection‐product CD34+ cell concentration, measured when PBV reached approximately 50 mL/kg, were compared. Absolute prediction error was compared within procedures. We also evaluated CD34 percent change (CD34% change), defined as the relative change in product CD34+ cell concentration from interim sampling to the final product, and factors associated with CD34% change ≤ −10%. Results Interim‐CD34‐based prediction showed a smaller absolute prediction error than Pre‐CD34‐based prediction ( p = 0.034). Median CD34% change was −3.6%, and CD34% change ≤ −10% occurred in 27.9% of procedures. Higher preprocedure platelet count was associated with this decrease. Conclusion Interim‐CD34‐based prediction improved yield estimation and may enable PBV optimization during apheresis while maintaining target doses.