Peripheral blood stem cell mobilization and engraftment after autologous stem cell transplantation with biosimilar rhG-CSF.

Introduction: Biosimilar versions of filgrastim [recombinant human granulocyte colony-stimulating factor (rhG-CSF)] are now widely available. To date, biosimilar rhG-CSF has demonstrated a comparable quality, safety and efficacy profile to the originator product (filgrastim [Neupogen(®)], Amgen Inc., CA, USA) in the prevention and management of neutropenia. Biosimilar rhG-CSFs have also been used to induce peripheral blood stem cell (PBSC) mobilization in patients undergoing autologous stem cell transplantation (AHSCT). The authors have examined the effectiveness of a biosimilar rhG-CSF (Zarzio(®), Sandoz Biopharmaceuticals, Holzkirchen, Germany) in two retrospective studies across two medical centers in Hungary.

Methods: In Study 1, 70 patients with hematological malignancies scheduled to undergo AHSCT received chemotherapy followed by biosimilar rhG-CSF (2 × 5 μg) for facilitating neutrophil, leukocyte, and platelet engraftment. In study 2, 40 additional patients with lymphoid malignancies and planned AHSCT received chemotherapy followed by biosimilar rhG-CSF for PBSC mobilization. The effectiveness of treatment was assessed by the average yield of cluster of differentiation (CD) 34+ cells and the number of leukaphereses required.

Results: In Study 1 (patients undergoing AHSCT), the median age was 56 years and most patients were male (60%). The conditioning regimens were mainly high-dose melphalan (n = 41) and carmustine (BiCNU(®), Bristol-Myers Squibb, NJ, USA), etoposide, cytarabine and melphalan BEAM (n = 21). Median times to absolute neutrophil and leukocyte engraftment were 9 (range 8-11 days) and 10 (8-12) days, respectively. Median time to platelet engraftment was 10.5 days (7-19 days). In Study 2, the patients' median age was 54 years and the majority (57.5%) were female. The median time interval between day 1 of mobilizing chemotherapy and first leukapheresis was 12 (9-27) days. In the autologous PBSC grafts, the median number of CD34+ cells harvested was 5.2 × 10(6)/kg (2.22-57.07 × 10(6)/kg). The median yield of CD34+ cells per leukapheresis product was 2.47 × 10(6)/kg. In total, 58 leukaphereses were performed in 40 successfully harvested patients.

Conclusions: In line with previous studies with originator rhG-CSF, the findings of this study indicate that biosimilar rhG-CSF following AHSCT is effective and generally well tolerated in the engraftment setting. In addition, biosimilar rhG-CSF is comparable to the originator rhG-CSF in terms of kinetics of PBSC mobilization and yield of CD34+ cells. In conclusion, the authors have demonstrated that the use of biosimilar rhG-CSF is effective and safe in autologous PBSC mobilization and engraftment after AHSCT.