Efficacy of a conversion from filgrastim to filgrastim-sndz in stem cell transplant patients undergoing mobilization

Abstract

During autologous stem cell transplant, granulocyte colony-stimulating factors (G-CSF) serve the integral role of mobilizing hematopoietic cells into the peripheral blood for subsequent collection by leukapheresis. Filgrastim (Neupogen®) is a G-CSF and affects hematopoietic cells by stimulating growth and differentiation of neutrophils. Filgrastim-sndz (Zarxio®), a biosimilar of filgrastim, received landmark approval as the first biosimilar product approved by the FDA in the United States. As a result of the recent FDA approval, our medical center made the conversion in August 2016 from using filgrastim to filgrastim-sndz to provide patients the same benefits of the filgrastim injection at a reduced cost. This retrospective, observational cohort study evaluated the comparative efficacy of the filgrastim-sndz biosimilar in 147 patients who underwent mobilization prior to stem cell transplant with filgrastim between 1 August 2015 and 31 July 2016 or filgrastim-sndz between 1 September 2016 and 30 November 2017. The mean number of CD34 cells collected during apheresis was 7.38 × 106 in the filgrastim group and 8.86 × 106 in the filgrastim-sndz group. Filgrastim-sndz was significantly non-inferior, as the difference between filgrastim and filgrastim-sndz was −1.48 × 106 with an upper 95% confidence bound equal to −0.24 × 106 that did not include the non-inferiority margin of 1 × 106 ( p = 0.0006). The median number of days of apheresis was 2 in both groups ( p= 0.3273). In conclusion, the biosimilar product was non-inferior for mobilization and the conversion from filgrastim to filgrastim-sndz afforded patients similar efficacy for mobilization in stem cell transplant at a reduced cost.