Efficacy and Cost Savings Associated with a Conversion from Filgrastim to Filgrastim-Sndz in Stem Cell Transplant Patients Undergoing Mobilization

Abstract

In patients undergoing autologous stem cell transplantation (aSCT), the recombinant human granulocyte colony-stimulating factor, filgrastim, has been historically utilized during mobilization. Filgrastim-SNDZ, a biosimilar of filgrastim, received landmark approval as the first biosimilar product approved by the FDA in the United States. Biosimilar products offer cost benefit over the reference product, while maintaining similar efficacy. As a result of the recent approval, our medical center made the conversion from using filgrastim to filgrastim-SNDZ as the preferred mobilizing agent to provide patients the same benefits at a reduced cost. The primary objective of this retrospective, observational cohort study was to assess the efficacy of filgrastim-SNDZ as a mobilizing agent in the SCT patient population compared to the formerly used reference product, filgrastim. The secondary objective was to confirm the cost savings associated with the conversion from filgrastim to filgrastim-SNDZ. Data was collected on two cohorts of patients undergoing mobilization prior to an aSCT who received either filgrastim or filgrastim-SNDZ. Efficacy was assessed based of the number of days of stem cell apheresis and number of CD34 stem cells collected during apheresis in both cohorts. Cost savings were assessed based on cost difference (average wholesale price) between the drug products. In total, 186 patients received an aSCT during this time frame. Sixty-nine patients were included in the filgrastim group and 78 were included in the filgrastim-SNDZ group. The difference in number of CD34 cells collected was not significant (p = 0.17). The median number of CD34 cells collected was 7.24 × 106 in the filgrastim group and 8.245 × 106 in the filgrastim-SNDZ group. The filgrastim-SNDZ group had a larger range of CD34 cells collected during apheresis than the filgrastim group. There was no statistically significant difference in number of CD34 cells collected between the groups in patients with multiple myeloma (p = 0.0969) or with non-Hodgkin's lymphoma (p = 0.976). Number of CD34 cells collected was also tested for non-inferiority with a non-inferiority margin of 0.73 (10%) and filgrastim-SNDZ was shown to be non-inferior in this outcome to filgrastim. The median number of days of apheresis was 2 in both groups and there was no significant difference in this outcome between the groups (p = 0.36). The cost comparison between groups showed significant cost savings with filgrastim-SNDZ. Annual cost savings is projected to be $92,000 for 93 patients receiving an average of 5 doses of filgrastim-SNDZ. This study shows that using filgrastim-SNDZ is an effective and cost savings option for mobilization prior to aSCT.