Pegfilgrastim for peripheral CD34+ mobilization in patients with solid tumours.

The efficacy of pegfilgrastim±chemotherapy for mobilizing stem cells in patients with solid tumours was assessed. In cycle 0, a 14-day prechemotherapy cycle, patients (N=61) were randomized open-label to single doses of pegfilgrastim (6, 12 or 18 mg) on day 1, or daily filgrastim (10 μg/kg) for 7 days. Mean peak peripheral CD34+ cell counts increased with pegfilgrastim dose, but were significantly higher than filgrastim only at the 18 mg dose (10.17 vs 4.96 × 104/ml; P=0.014). In the clinically relevant period of days 3–7, both 12 and 18 mg pegfilgrastim doses produced significantly higher peak CD34+ counts (8.18 and 9.96 vs 4.51 × 104/ml for filgrastim; P=0.034 and 0.006). In cycle 1, patients received carboplatin/paclitaxel on day 1, followed from day 2 by pegfilgrastim 6–18 mg or daily filgrastim (5 μg/kg/day for 14 days) as per randomization in cycle 0. There were no significant differences in mean peak CD34+ count between pegfilgrastim and filgrastim, but there was an advantage for pegfilgrastim 18 mg in the relevant period of days 7–12 (3.14 vs 1.19 × 104/ml; P=0.043). A single pegfilgrastim dose (6 mg) could be substituted for daily filgrastim in cytokine-only peripheral CD34+ cell mobilization.