Mobilization of Allogeneic Peripheral Blood Stem Cells in Family Donors with Single-Dose Pegfilgrastim.

The standard procedure for obtaining peripheral blood stem cells (PBSC) is donor mobilization with G-CSF. Pegfilgrastim is a covalently bound conjugate of filgrastim and monomethoxypolyethylene glycol with longer half-life elimination due to decreased plasma clearance and could represent an alternative approach for PBSC mobilization in healthy donors.

From July 2006 till August 2009 28 related healthy donors (50% male, 50% female) were treated with single dose of 12 mg pegfilgrastim for mobilization of allogeneic PBSC. The harvests were performed as large-volume, continuous-flow collections using a Cobe Spectra blood cell separator on day 4 and if necessary on day 5 of the mobilization regimen. In case of inadequate CD34⁺ counts (less than 4×10⁶/kg body weight of recipient on day 5), stimulation was continued with filgrastim. In addition, the serum level of filgrastim was determined twice daily.

We present the results of 27 donors (the results of the 28^th donor are still pending). In all 27 cases the harvests were successful. In 22 out of 27 donors (82%) only a single apheresis was needed to reach the target. Two of the donors required additional treatment with non-pegylated filgrastim.

The maximal concentration of circulating CD34+ cells was achieved on day 4 (median 74.3/μl; range 24.6-136.6). The median yield of CD34+ cells was 5.9×10⁶/kg of the recipients body weight (range 3-14.5), and the median CD3+ count was 9.1×10⁸/kg of the recipient body weight (range 1.4-6.2). Serum filgrastim level peak was on day 2 of the mobilization regimen with a median level of 226 ng/ml (range 35 to 1123 ng/ml), thus preceding the increase of CD34+ cells in blood. The main adverse events were WHO grade 1 and included headaches, bone pain and transient elevations of alkaline phosphatase and lactate dehydrogenase.

PBSC mobilization with a single dose of pegfilgrastim is feasible for healthy donors. The graft composition was comparable to that obtained with the conventional regimen of short-term G-CSF. Long-term follow-up of healthy donors treated with pegfilgrastim should be further investigated.

No relevant conflicts of interest to declare.