SHORT REPORT Prospective randomized study comparing the efficacy of bioequivalent doses of glycosylated and nonglycosylated rG-CSF for mobilizing peripheral blood progenitor cells F. DE A RRIBA, M. L. L OZANO, F. O RTUN ˜ O, I. HERAS , J. M. MORALEDA AND V. V ICENTE Unit of Haematology and Haemotherapy, School of Medicine, Hospital General Universitario, Murcia, Spain Received 8 August 1996; accepted for publication 16 October 1996 Summary. Thirty patients diagnosed with breast cancer were included in a prospective randomized study comparing the in vivo priming effect of bioequivalent doses of glycosylated (lenograstim) and nonglycosylated (filgrastim) rG-CSF administration. Analysis of the efficacy of equivalent biological doses of both rG-CSFs showed no significant differences either in the mobilization of the subpopulations of PBPC considered (CD34 + , CD34 + /38 ¹ , CD34 + /DR ¹ ), the content of such CD34 + cell subsets in the leukapheresis product, or the cost of the mobilization and collection procedures between both recombinant molecules. These results suggest that priming with bioequivalent doses of the two commercially available forms of glycosylated or non- glycosylated rG-CSF has a similar in vivo effect on PBPC mobilization. Keywords: filgrastim, lenograstim, granulocyte colony- stimulating factor, CD34, mobilization. Recombinant human granulocyte colony-stimulating factor (rG-CSF) is available for clinical use in Europe and Japan in two forms: a nonglycosylated form (Escherichia coli derived) and a glycosylated form [Chinese Hamster Ovary (CHO) cell- derived]. Glycosylation of the rG-CSF molecule has been postulated to confer greater biological activity both in in vitro neutrophil colony assays (Nissen, 1994; Nissen et al, 1994) and in in vivo studies of peripheral blood progenitor cells (PBPC) mobilization (Ho ¨glund et al, 1995). These assays were all performed on a mg basis comparison between the glycosylated and nonglycosylated product. In 1994 the Expert Committee on Biological Standardization (ECBS) of the World Health Organization (W.H.O.) established an international potency standard for G-CSF (W.H.O., 1994), based in an international collaborative study (Mire-Sluis et al, 1995) which showed that mass units were not equivalent between different recombinant materials. Since then, by means of validated bioassays, the potency of all available rG-CSFs has been calibrated, in terms of biological units, compared to the international standard. The aim of this in vivo prospective randomized single-blind study was to compare the efficacy of equivalent doses – in terms of biological activity – of glycosylated (lenograstim) and nonglycosylated (filgrastim) rG-CSF for mobilizing PBPC. Moreover, we assessed the effect of both rG-CSFs on the release of primitive subsets of haemopoietic cells to peripheral blood (PB), analysed by the presence of CD34 + 38 ¹ and CD34 + DR ¹ phenotypes, and quantitated the content of such cells in leukapheresis preparations. MATERIAL AND METHODS Thirty patients who had histologically-proven breast cancer (21 stage II or III, and nine stage IV) were randomized to receive either glycosylated rG-CSF (lenograstim: mean age 41, range 35–56 years) or nonglycosylated rG-CSF (filgrastim: mean age 44, range 31–57 years). Stage II or III patients (10 filgrastim, 11 lenograstim) had received five to eight cycles of chemotherapy using CEF (cyclophosphamide, 600 mg/m 2 , day 1; epirubicin, 90 mg/m 2 , day 1; 5-fluorouracil, 600 mg/ m 2 , day 1), whereas patients with stage IV breast cancer (five filgrastim, four lenogastrim) had been treated with different regimens of induction chemotherapy. 15 patients received nonglycosylated rG-CSF (Filgrastim, Amgen, Thousand Oaks, Calif., U.S.A.) at a mean  SEM dose of 0 . 84  0 . 01 MU/kg/d [8 . 4  0 . 1 mg/kg/d]), and glycosylated rG-CSF (Lenograstim, Chugai-Rho ˆne-Poulenc, Antony, France) was administered to 15 patients at a mean  SEM dose of 0 . 82 0 . 02 MU/kg/d [6 . 4  0 . 1 mg/kg/d]). British Journal of Haematology , 1997, 96, 418–420 418  1997 Blackwell Science Ltd Correspondence: Professor V. Vicente Garcı ´a, Centro Regional de Hemodonacio ´n, C/. Ronda de Garay s/n, 30003 Murcia, Spain.