Clinical and Ultrasonic Evaluation of Spleen Size during Peripheral Blood Progenitor Cell Mobilization by Filgrastim: Results of an Open-Label Trial in Normal Donors

Rare reports of splenic rupture have been associated with filgrastim treatment during peripheral blood progenitor cell (PBPC) mobilization in allogeneic donors. We performed a prospective study of spleen volume change in 309 normal donors who received filgrastim according to local institutional practices. Splenic assessments consisted of ultrasonography and clinical examination at baseline and on the first day of leukapheresis in 304 donors. Of these, 90 donors were also examined 2 and 4 days after the first leukapheresis and 7 days after the last leukapheresis. Median spleen volume increased 1.47-fold (range: 0.63 to 2.60) on the first leukapheresis day and declined to near pretreatment levels at 7 days after last leukapheresis. Nine percent of donors had ≥2-fold increase in splenic volume. Spleen palpability did not correlate with change in spleen volume. No donors experienced a splenic rupture. There was no correlation between change in spleen volume and filgrastim dosage, number of doses/day, peak absolute neutrophil count (ANC), CD34⁺ yield, or donor baseline weight. Most donors experienced ≥1 adverse event, with 6 donors reporting serious adverse events. We conclude that the increase in splenic volume during PBPC mobilization in donors was transient, and that filgrastim was well tolerated in this study. This trial was registered at www.ClinicalTrials.gov as NCT00115128.

Key Words: Stem cell, Mobilization, Spenomegaly, Spleen size