How long after neutrophil recovery should myeloid growth factors be continued in autologous hematopoietic stem cell transplant recipients?

Growth factors are routinely used after autotransplantation to accelerate hematopoietic recovery, and are continued until the absolute neutrophil count (ANC) is ≥0.5 × 10⁹/l on 3 consecutive days. Since ANC often increases to very high levels with this strategy, we discontinued growth factor on the first day ANC reached 0.5 × 10⁹/l in 45 patients (Study Group), and compared their subsequent ANC to 108 historic controls who received growth factor longer. While ANC on the day after reaching 0.5 × 10⁹/l was comparable between groups, ANC on the third day was significantly higher in the Control Group (2.3 vs 4.9 × 10⁹/l; P = 0.0003). When compared to the first day, ANC in the Study Group was higher by a median of 140% on the third day and by 450% in the Control Group (P = 0.0002). A significantly higher proportion of patients experienced a decline in ANC after the first day in the Study Group. However, only one patient in the Study Group became neutropenic transiently and ANC recovered spontaneously the next day. The incidence of fever and hospitalization were comparable. We conclude that growth factors can be discontinued after autotransplantation the day the ANC reaches 0.5 × 10⁹/l, without compromising neutrophil recovery.