Clinical Outcomes of Treatment with Filgrastim Versus a Filgrastim Biosimilar and Febrile Neutropenia-Associated Costs Among Patients with Nonmyeloid Cancer Undergoing Chemotherapy.

BACKGROUND: Granulocyte colony-stimulating factors such as filgrastim are used to decrease the incidence of febrile neutropenia (FN) among patients with nonmyeloid cancers undergoing chemotherapy treatment. Although the biosimilar filgrastim-sndz has been approved in the United States since 2015, limited real-world comparisons of filgrastim-sndz versus reference filgrastim (filgrastim-ref) have been conducted.
OBJECTIVE: To compare FN incidence and assess overall FN-related health care resource utilization and medical costs among U.S. patients with non-myeloid cancer who received filgrastim-sndz or filgrastim-ref during their first chemotherapy cycle.
METHODS: This was a retrospective claims analysis of patients with non-myeloid cancer who were enrolled in commercial or Medicare Advantage insurance plans from March 2015 through June 2016 and received filgrastim-sndz or filgrastim-ref during their first observed chemotherapy cycle. Patients with evidence of hematopoietic stem cell transplantation or pregnancy and those with missing demographic information were excluded. FN was defined on the basis of diagnosis codes for neutropenia and fever (N/F); neutropenia and infection (N/I); and neutropenia, infection, and fever (N/I/F). Cohorts were adjusted for differences in baseline patient characteristics using the inverse probability of treatment weighting (IPTW) method, and equivalence testing was used to compare the proportion of patients who developed FN between weighted cohorts. On the basis of the range of neutropenic fever incidence found in the PIONEER clinical trial, FN incidence was considered equivalent if 90% CIs for between-cohort differences were within ± 6%. Mean FN-related health care resource utilization and total FN-related medical costs were calculated for the overall study population.
RESULTS: A total of 3,542 patients were included in the study (172 filgrastim-sndz; 3,370 filgrastim-ref; mean ages 62.1 years and 64.7 years, respectively). After IPTW, there were 162 patients in the filgrastim-sndz cohort and 3,297 in the filgrastim-ref cohort (mean age 64.5 years for both). FN incidence in the weighted filgrastim-sndz versus filgrastim-ref cohorts, respectively, was 1.4% versus 0.9% for N/F, 2.3% versus 1.7% for N/I, and 0.0% versus 0.3% for N/I/F; FN incidence was statistically equivalent between treatment cohorts. Among patients in either treatment cohort who developed FN, the proportion with FN-related inpatient stays during the first chemotherapy cycle ranged from 35.0% for N/I to 70.0% for N/I/F. Mean (SD) FN-related total medical costs across all patients who developed FN were $11,977 ($18,383) for N/F, $8,040 ($14,809) for N/I, and $21,733 ($30,003) for N/I/F, in 2015 U.S. dollars. For all 3 definitions of FN, the largest proportions (73.5%-93.4%) of medical costs were inpatient related.
CONCLUSIONS: In this real-world study of patients with nonmyeloid cancers undergoing chemotherapy, the incidence of FN was statistically equivalent between individuals treated with filgrastim-sndz versus filgrastim-ref during their first chemotherapy cycle. FN-related health care resource utilization and medical costs among patients who developed FN were substantial. DISCLOSURES: This work was funded by Sandoz, which participated in the study design, data interpretation, writing and revision of the manuscript, and decision to submit the manuscript for publication. Balu and Campbell are employees of Sandoz, which is the manufacturer of the filgrastim biosimilars Zarzio and Zarxio. DeLeon was an employee of Sandoz at the time this study was conducted. Lal, Brekke, Elliott, and Korrer are employees of Optum, which was contracted by Sandoz to conduct this study.