Biosimilar Compared with Originator Filgrastim for Autologous Stems CELL Mobilisation: A Prospective-Historical Control Study in Multiple Myeloma REAL-Life Setting

Introduction:Biosimilars of filgrastim have been available since 2008 and are now in widespread use also for stem cells (SCs) mobilization. There are no previously published data on the use of biosimilar G-CSF for peripheral blood (PB) SCs collection only in patients with Multiple Myeloma (MM) as they always had been presented aggregated with other different hematological malignancies. Here we report the use of a biosimilar filgrastim (Zarzio®) compared with a matched historical control group in PBSCs in patients with de-novo MM treated with reference product (Neupogen®) and scheduled to receive a double autologous transplantation.

Material and Methods: A total of 26 consecutive patients received biosimilar filgrastim after cyclophosphamide (CTX) 4g/m2 chemotherapy for PBSCs mobilization between January and July 2014, this group was compared with a matched historical control cohort (n=26) who had been treated with originator filgrastim between 2012 and 2013. In both groups G-CSF was administered 5 μg/kg/day until almost a minimal count of 4 x106 CD34+ cells/kg was collect. Monitoring of peripheral blood CD34+ cell concentrations began as soon as WBC recovery reached 1x10⁹/L and leukapheresis was initiated when the CD34⁺cell concentration reached 10/mL.

Results: Characteristics (age, gender, body weight, type of induction CHT, radiation therapy) were similar in both groups. The median peak CD34+ cells value was 187.8 ± 159.5 x ml in the biosimilar group compared with 223.7 ± 206.5 x ml in the originator group (P=n.s.). The median number of leukapheresis necessary to harvest a minimal count of 4 and 8 x10E6 CD34+/kg was similar in both biosimilar and originator groups: 1.4 ± 0.6 vs 1.3 ± 0.6 (P=n.s.) and 1.8 ± 0.8 vs 1.4 ± 0.7 (P=n.s), respectively. One and 3 patients failed to mobilize 4 and 8 x 10 E /kg CD34+ cells in the biosimilar group compared with 3 and 8 patients in the originator group (P=n.s), respectively). Short-term hematological reconstitution was evaluated for all transplanted patients. Number of CD34+ cells reinfused at the first transplant were 4.8 ± 0.75x10E6/Kg in the biosimilar group compared with 5.1 ± 0.75x10E6/Kg in the originator group (P=n.s.). Median time to neutrophil engraftment (>500/μl) was similar in both the biosimilar and originator groups (10.7 ± 0.8 vs 10.3 ± 1.1 days; P=n.s), as was platelet recovery (13.6 ± 1.8 vs13.4 ± 1.2 days; P=n.s.

Conclusions:Our study shows that biosimilar filgrastim administered following chemotherapy is equivalent to originator filgrastim for autologous stem cell mobilization and PBSCs collection when used with the same schedules and doses in a MM real life setting. Long-term follow-up is required to confirm the safety of biosimilar and originator G-CSF.