A risk-adapted protocol for delayed administration of filgrastim after high-dose chemotherapy and autologous stem cell transplantation

Introduction: The routine use of recombinant human granulocyte-colony stimulating factor (rhG-CSF) after high-dose chemotherapy and autologous stem cell transplantation (auto-SCT) is associated with increased costs. We prospectively explored a strategy that used prophylactic delayed filgrastim only in patients with risk factors. Patients and Methods: This sequential cohort analysis compared the outcomes of consecutive patients, treated on the risk-adapted protocol (RAP) (risk factors: prior febrile neutropenia; age >60 years; and CD34+ cell infused dose of <2 × 10^6//kg), who received filgrastim from day +6 after auto-SCT with a historical cohort (historical day-1 cohort [HD1]), who received filgrastim from day +1. Results: Eighty-two patients were treated in the RAP cohort and compared with 115 patients in the HD1 cohort. There were no differences in median age (55 years) or median CD34+ cell dose (5.21 × 10⁶/kg [range, 2-62.2 × 10⁶/kg] vs. 5.24 × 10⁶/kg [range, 2.4-29.8 × 10⁶/kg]). Filgrastim was used for 6 fewer days in the RAP cohort (median 5 days [range, 0-11 days] vs. 11 days [range, 9-47 days]). There was a small absolute but significant difference in median time to neutrophil recovery in the HD1 cohort for the whole group, 10 days (range, 8-46 days) vs. 11 days (range, 9-22 days) (P =.03) and in patients with myeloma; 10 days (range, 9-14 days) vs. 11 days (range, 9-18 days) (P <.0001) as compared to the RAP cohort. There was no difference in median inpatient duration, 13 days (range, 10-26 days) vs. 12 days (range, 1-38 days) (P =.22) and 3-year survival (79% vs. 83% [P =.43]) between HD1 and RAP cohorts respectively. Conclusions: The use of a RAP to identify patients likely to benefit from prophylactic filgrastim is safe and results in cost savings. Patients with myeloma benefit from earlier introduction of filgrastim in terms of neutrophil recovery; this disease-specific observation is an important consideration for future studies.