Biosimilar Compared With Originator Filgrastim For Related-Donor Allogeneic Stem Cell Mobilisation: A Prospective-Historical Control Study

Biosimilars of filgrastim have been available for over five years In Europe, where their use now exceeds that of the originator product. However, some professional bodies have raised concerns over their use in healthy donors for allogeneic mobilisation given the absence of clinical data in this setting. Here we report the use of biosimilar filgrastim compared with a matched historical control group in allogeneic transplant.

A total of 26 healthy related-donors (parent or sibling) received biosimilar filgrastim (HX575) for allogeneic stem cell mobilisation at a single centre between 2011 and 2013. Donors and recipients were compared with a matched historical control group (n=48) who had been treated with original filgrastim (Neupogen) at the same centre between 2005 and 2011. Donors and patients in both groups were treated according to the same clinical protocol, with G-CSF 10 µg/kg/day administered to donors on days 1-5 with leukapheresis performed on day 5.

Donor and recipient characteristics (age, gender, body weight) were similar in both groups. Both the biosimilar and originator groups had similar donor mean white blood cell counts at baseline (6.13 vs 6.24 x 10⁹/l) and on day 5 (46.9 vs 45.3 x 10⁹/l). Mean donor CD34+ cell count on day 5 was 92/µl in the biosimilar group and 88/µl in the originator group (p=0.713). Mean number of CD34+ cells per recipient body weight was 9.7 x 10⁶ in the biosimilar group and 8.00 x 10⁶ in the originator group (p=0.437). Occurrence and intensity of bone pain was similar in donors in both groups. The majority of recipients in both groups had acute leukemia, myeloma, lymphoma or congenital immunodeficiency syndrome and around half underwent a non-myeloablative transplant. Median time to neutrophil engraftment (>500/µl) was similar in both the biosimilar and originator groups (16.5 [range 11-44] vs 15.0 [range 9-23] days; p=0.078), as was platelet recovery (>20 g/l) (12.5 [range 8-28] vs 12.5 [range 3-38] days; p=0.990). Acute graft-versus-host disease (GVHD) occurred in 27% of patients in the biosimilar group and 38% patients in the original group, while chronic GVHD occurred in 15% and 19% of recipients, respectively.

Biosimilar G-CSF is as effective and well tolerated as originator G-CSF for related-donor allogeneic stem cell mobilisation. Long-term follow-up of donors is required to confirm the safety of biosimilar and originator G-CSF.

Lefrère: Sandoz Biopharmaceuticals: Consultancy, Honoraria. Turner:Sandoz Biopharmaceuticals: Employment.