Study: Biosimilar Filgrastim Use Is Concordant With EORTC Guidelines

Some studies have found that granulocyte colony-stimulating factor (G-CSF) therapies are underused for the prophylaxis of febrile neutropenia (FN) in Europe, but the widespread availability of cheaper biosimilar options has led to increased use. A new study, published in BMC Cancer, sought to examine the use of the biosimilar filgrastim, Zarzio (sold in the United States as Zarxio), by oncologists and hematologists in patients receiving chemotherapy, and found that the use of the biosimilar in patients with solid tumors is now generally in line with the European Organisation for Research and Treatment of Cancer (EORTC) guidelines.

In the ZOHé study, 1816 patients (1179 with solid tumors) were evaluated at 125 sites in France between 2013 and 2014. Among the patients with solid tumors (data for patients with hematologic malignancies will be reported separately), data from follow-up visits were collected from 1141. At baseline, 9.3% of patients had experienced at least 1 episode of severe neutropenia, and 35.8% had experienced prior FN. Chemotherapy planned at study inclusion varied by tumor type.

Prescriptions for the biosimilar filgrastim were “predominantly in accordance with the label indication,” wrote the authors, with the first dose administered 24 hours or more after chemotherapy, and with daily dosing that continued at 0.5 MIU/kg per day until neutrophil count had recovered, up to 14 days. The biosimilar was initiated on a median day 4 after the chemotherapy cycle. Median duration of treatment with the biosimilar was 5 days.

The majority of the patients (65.8%) were in cycle 1 of chemotherapy at inclusion, and the biosimilar filgrastim was administered for a median of 4 cycles, though mean number of cycles varied by tumor type, disease stage, and chemotherapy protocol.

In total, 39.4% of patients stopped receiving the biosimilar after a median of 3 cycles. The main reason for discontinuation was cessation of chemotherapy (74.6%).

The biosimilar was prescribed as the primary prophylaxis for the majority of patients (65.8%), and patients with a high FN risk category were more likely to be given the biosimilar as primary prophylaxis. The majority of the primary prophylaxis patients were female (53.9%), had a mean age of 62.2  (± 11.8) years, had advanced tumors (55.9% had stage IV tumor), had a good performance status (81.5% had Eastern Cooperative Oncology Group performance score of less than  2), and had few prior episodes of severe neutropenia or FN.

The primary prophylaxis group was more likely to be prescribed the biosimilar filgrastim for reasons of concomitant pathologies or poor functional or nutritional status versus patients who received the biosimilar in subsequent cycles.

Almost all of the patients who received the biosimilar filgrastim (99.1%) had at least 1 patient-related EORTC risk factor for FN. Clinicians’ reasons for prescribing filgrastim were mostly related to age, functional or nutritional status, leucocyte levels, and concomitant pathologies. Notably, clinicians tended to assess a higher FN risk category for a given chemotherapy regimen than that documented in EORTC guidelines, and 10.8% of patients were given the biosimilar filgrastim despite low FN risk.

In total, 7.6% of patients had severe neutropenia, and 3.5% had FN. There were 62 adverse events (AEs) associated with the biosimilar filgrastim, and these occurred in 3.4% of patients. Fourteen of these AEs were considered serious. Discontinuation due to toxicity was observed in less than 5% of patients.

“Zarzio use in this study is largely in keeping with EORTC guidelines for G-CSF prophylaxis for neutropenia,” concluded the authors, adding that patient-related risk factors are a strong driver of providers’ decisions to initiate treatment with biosimilar filgrastim.

Reference

Roché H, Eymard JC, Radji A, et al. Biosimilar filgrastim treatment patterns and prevention of febrile neutropenia: a prospective multicentre study in France in patients with solid tumours (the ZOHé study). BMC Cancer. 2018;18:1127. doi: 10.1186/s12885-018-4986-1.