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Chen X, Agiro A, Barron J, Debono D, Fisch M. Early Adoption of Biosimilar Growth Factors in Supportive Cancer Care. JAMA Oncol. 2018;4(12):1779–1781. doi:10.1001/jamaoncol.2018.5090
In 2010, the US Food and Drug Administration established an approval pathway for biosimilar agents, biological agents with an active ingredient highly similar to the reference biological agent, to facilitate drug competition and lower costs. It is unclear whether biosimilar drugs could yield large cost savings in the United States given the previously documented market and regulatory barriers.1-3 Moreover, few studies have investigated the real-world safety and effectiveness profile of biosimilar agents compared with that of brand-name (reference) biological agents.
The colony-stimulating growth factors (CSF) filgrastim-sndz and tbo-filgrastim reduce risk of chemotherapy-induced neutropenia and were the first biosimilar agents approved in the United States. We examined the incidence of febrile neutropenia (FN), CSF-related adverse events (AEs), and drug cost among commercially insured US patients with cancer treated with chemotherapy.
This retrospective observational study analyzed administrative health claims data from a large commercially insured population. Only deidentified data were used, and the study was exempt from review by an institutional review board. The study included commercially insured adults with cancer treated with chemotherapy who received reference filgrastim or biosimilar filgrastim from September 1, 2012, through April 30, 2017. Patients with atypical risk for FN (ie, those with previous bone marrow or stem cell transplant or prior FN) were excluded from the study. The population was divided into either biosimilar or reference filgrastim groups according to the earliest filgrastim use (index date).
Patients were observed for 21 days postindex to assess filgrastim treatment cost (total and per day of use) and the incidence of FN and AEs (eg, spleen rupture, acute respiratory syndrome, serious allergic reactions). Two validated claim-based algorithms (neutropenia and/or fever requiring hospitalizations) were used to capture the incidence of FN.4 Study outcomes were compared using multivariable regression model adjusted for baseline risk factors (Table 1).
Of 11 202 patients included in the study, 1531 (13.7%) used biosimilar CSF. The median patient age was 61 years, 6927 patients (61.8%) were female, and 5782 patients (51.6%) had at least 1 non–cancer-related comorbid condition. No meaningful differences in baseline risk factors were observed between the filgrastim and biosimilar filgrastim groups. Biosimilar filgrastim accounted for 7% of filgrastim users in 2014 (171 of 2580), which increased to 16% in 2015 (384 of 2420) and to 36% in 2016 (778 of 2180).
Incidence rates of strict (neutropenia and fever) and broad (neutropenia or fever) definitions of FN were similar between the 2 groups. The incidence of broad FN in patients receiving biosimilar agents was 11.3%, whereas the incidence in those receiving brand-name agents was 9.4% (P = .12). Incidence rates in patients with strict FN were 4.5% and 3.9% in patients receiving biosimilar agents or brand-name agents, respectively (P = .39; Table 1). No difference in the rate of AEs was observed (biosimilar agents, 6.9%; brand-name agents, 6.4%; P = .72). The mean filgrastim drug costs per patient were similar between the biosimilar and reference filgrastim groups (biosimilar agents, $2522; brand-name agents, $2516; P = .27; Table 2); the cost per day of use was 2.3% less for biosimilar filgrastim (biosimilar agents, $731; brand-name agents, $748; P = .02). Compared with reference filgrastim, the mean total costs per patient and per day of use were 6.1% and 10.8% less for filgrastim-sndz (P = .07 and P < .001), respectively, and were marginally higher for tbo-filgrastim (2.7% and 2.3%, respectively; P = .64 and P = .50, respectively).
The findings suggest biosimilar filgrastim is similar to reference filgrastim in terms of safety and effectiveness in the real-world setting. The results are reassuring regarding the intended clinical outcomes associated with filgrastim. The savings associated with biosimilar filgrastim have been modest because early adoption of biosimilar agents has been slow, and current pricing for biosimilar drugs is closely tracking that of the brand-name product. However, the market for biosimilar agents seems to be increasing over time, indicating broader acceptance of these drugs. As more biosimilar agents enter the market, continuing research is needed to assess the drug uptake, clinical outcomes, and realized cost savings. Our study, which was conducted using claims data, has the advantage of rich cost information, but it is limited by the lack of clinical detail for most patients.
Accepted for Publication: August 31, 2018.
Corresponding Author: Abiy Agiro, PhD, HealthCore, Inc, 123 Justison St, Ste 200, Wilmington, DE 19801 (email@example.com).
Published Online: November 1, 2018. doi:10.1001/jamaoncol.2018.5090
Author Contributions: Ms Chen and Dr Agiro had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Chen, Agiro, Barron, Fisch.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Chen, Agiro.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Chen, Agiro.
Obtained funding: Agiro.
Administrative, technical, or material support: Chen.
Study supervision: Agiro, Barron.
Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Ms Chen, and Drs Agiro and Barron reported being full-time employees of HealthCore. Dr Debono reported being a full-time employee of Anthem and has stock and other ownership interest in Eli Lilly. Dr Fisch reported being a full-time employee of AIM Specialty Health and has stock and other ownership interest in Anthem. No other disclosures were reported.
Funding/Support: This study was funded by Anthem Inc.
Role of the Funder/Sponsor: The sponsor had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation of the manuscript; or the decision to submit the manuscript for publication.
Disclaimer: The interpretation and reporting of these data are the sole responsibility of the authors.
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