In this paper, the group from Pamplona shows data of stem cell mobilization with filgrastim (G-CSF) in 36 healthy family donors, of which 18 underwent stem cell mobilization with Neupogen and 18 with the biosimilar Zarzio. In this retrospective observational noninterventional study, they showed that with a median follow up time of 13.5 months Zarzio appears to be safe and with a comparable safety profile as Neupogen. In terms of efficacy, no differences were observed regarding circulation CD34+ cells; however, higher numbers of CD 34+ cells were harvested in donors mobilized with Neupogen. This can however be explained in part by the change of Apheresis device (in all 18 donors mobilized with Neupogen the COBE Spectra was used, and in 15 of the Zarzio mobilized donors Spectra Optia was used as apheresis device). The processed blood volume was higher with the COBE Spectra.  However, 3 out of 18 donors mobilized with Zarzio failed to mobilize the optimal cell dose.
Engraftment was comparable in the two groups.
Given retrospective design of this study, the small donor numbers and the short follow up time the results have to be interpreted with care. More long term follow up data preferably in registries (such as e.g. EBMT Donor Outcome Registry) is needed to determine the safety of donor stem cell mobilization with biosimilars

Marıa Luisa Antelo,et al. , Journal of Clinical Apheresis 31:48–52 (2016)