A Real-World Analysis of Filgrastim and Biosimilars for Engraftment After Hemopoietic Cell Transplantation: Balancing Efficacy and Economics

Presenting Authors: Dennis Marjoncu, PharmD, BCOP, and Kori Holman, PharmD, BCOP, Methodist Cancer Institute, Memphis, TN

BACKGROUND: Hematopoietic cell transplantation (HCT) is a consolidative treatment for hematologic malignancies, with granulocyte colony-stimulating factors, such as filgrastim, facilitating neutrophil engraftment. Biosimilars have gained traction in solid-tumor malignancies as a result of their cost-effectiveness, but real-world evidence of their impact after HCT remains limited.

OBJECTIVE: To evaluate the efficacy and cost implications of filgrastim biosimilars in neutrophil engraftment after HCT.

METHODS: A retrospective analysis was conducted at Methodist University Hospital from 2015 to 2023, evaluating filgrastim to filgrastim-sndz after a formulary switch in September 2020. Data were collected for patients receiving reference filgrastim or filgrastim-sndz post-HCT and stratified by transplant type (autologous vs allogeneic). The primary outcome was neutrophil engraftment time, with secondary outcomes including length of stay (LOS), incidence of engraftment syndrome, bone pain, and cost-savings.

RESULTS: A total of 41 patients received filgrastim-sndz and 188 patients received filgrastim. The baseline characteristics were primarily similar between the groups, including median age (55 years vs 59 years), male sex (56% vs 55%), and indication for HCT of multiple myeloma being the most common (37% vs 44%). There was a difference in the type of allogeneic donor (P=.014), with more mismatched unrelated donors in the filgrastim-sndz arm (11% vs 0%). In the autologous HCT group, filgrastim-sndz recipients had a significantly shorter median time to neutrophil engraftment (6 days vs 8 days; P<.001) and LOS (13.5 days vs 18 days; P=.038). The total cumulative dose per patient was also lower in the filgrastim-sndz group (2880 mcg vs 3840 mcg; P<.001), providing a 56% cost-savings (P<.001). Bone pain was not significantly higher in the filgrastim-sndz group (18% vs 7%; P=.096). In the allogeneic HCT group, there were no significant differences in median time to neutrophil engraftment (9 days vs 10 days; P=.514), LOS (28 days vs 25 days; P=.169), or cumulative dose per patient (6240 mcg vs 4800 mcg; P=.330), with a 24% cost-savings, although this was not statistically significant. The rates of engraftment syndrome, bone pain, graft failure, and dose escalation were comparable between the groups.

CONCLUSION: This study supports the real-world efficacy of filgrastim-sndz in post-HCT neutrophil engraftment, demonstrating comparable clinical outcomes to reference filgrastim while also providing cost-savings opportunities, particularly in autologous HCT.

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