Pegfilgrastim successfully mobilizes megakaryocyte progenitors into the peripheral blood in subjects with solid...

Cytokine-mobilized PBPC transplants result in rapid neutrophil and platelet engraftment following high-dose chemotherapy. A total of 61 patients with solid tumours, sensitive to carboplatin and paclitaxol, were recruited as part of a phase I/II study and randomized to receive a single dose of 6, 12 or 18 mg pegfilgrastim on day 1 of a 14-day prechemotherapy cycle or daily filgrastim (10 microg/kg) for up to 7 days. The kinetics of megakaryocyte progenitor mobilization were studied using immunohistochemical assays and flow cytometry in a subset of 31 patients. There was no significant difference among treatment groups with respect to the timing of total progenitor colony-forming units (CFUs) and megakaryocyte progenitor (CFU-MK) mobilization, with the highest median peak falling on day 4/5 in all groups. In the pegfilgrastim 18 mg group, the mean peak total CFUs and CFU-MK were statistically significantly higher than in the filgrastim group (2.031x10(4) vs 8.06x10(3) per millilitre, P=0.024 and 1.12x10(4) vs 4.56x10(3) per millilitre, P=0.024, respectively). The kinetic profiles generated using immunohistochemical assays for CFU-MK and FACS analysis for CD41a were closely correlated suggesting that CD41a can be used as a surrogate marker for megakaryocytic mobilization.