Of note, in this study, rHuG-CSF was used only to correct the neutropenia and the drug was stopped when the neutrophil count was above 1,000/μL, the mean duration of use was 3.8 ± 0.8 days, and the patients had been on cyclophosphamide prior to the neutropenia that could have prevented a disease flare. This evidence concerns the gene CSF2 and neutropenia.