French Clinicians' Use of Zarzio for Neutropenia Risk Driven by Patient Factors

Data from a recent study show that biosimilar filgrastim is readily used in France for the prophylaxis of chemotherapy-induced neutropenia. The data also demonstrate that clinicians’ assessment of febrile neutropenia (FN) risk is driven by patient factors more than by the European Organisation for the Research and Treatment of Cancer’s (EORTC) risk category of the chemotherapy regimen.

A filgrastim biosimilar with demonstrated equivalence in clinical safety and efficacy to the reference filgrastim (Novartis’ Neupogen), Zarzio is mostly used as primary prophylaxis for chemotherapy-induced neutropenia in patients with solid tumors or hematological malignancies (HM). Data from the ZOHé study on Zarzio, sponsored by Sandoz, were reported in the June 2017 issue of Clinical Lymphoma, Myeloma & Leukemia.

The prospective, observational, multicenter study was conducted between June 2013 and April 2014 across 125 sites in France in order to assess the use of biosimilar filgrastim Zarzio in adults undergoing chemotherapy for either solid tumors (1174 patients) or a HM (633 patients). The present publication reports only the results for the use of Zarzio in patients with hematologic malignancy who had a first prescription for the biosimilar filgrastim.

The biosimilar filgrastim was administered for a median of 4 cycles of chemotherapy across the cohort. Treatment stayed constant in subsequent cycles for 89.6% of patients; among the 10.4% of patients who had treatment modifications, most changes were to treatment duration. Overall, 28.6% of patients stopped receiving biosimilar filgrastim before the end of the study, mostly due to cessation of chemotherapy; 8 patients stopped treatment because of adverse events linked to the drug.

All treatment guidelines recommend granulocyte colony-stimulating factor (G-CSF) prophylaxis where a risk of FN due to chemotherapy is greater than or equal to 20%, and for patients with intermediate risk (10% to 20%) who have additional risk factors (eg, 65 years or older, advanced stage of disease, previous episodes of FN, low performance status, and comorbidities). In the study, most patients had 2 or more EORTC patient-related risk factors for FN. Chemotherapy dose intensity was maintained in 85.2% of evaluable patients and 89.6% of patients with non-Hodgkin lymphoma receiving rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone. A total of 53 adverse events (AEs) associated with Zarzio occurred in 4.9% of all patients. None of the AEs were reported as being serious.

The study’s results suggest that, in real-world practice, clinicians predominantly give biosimilar filgrastim to patients whom they consider to be at high risk of FN, either due to their chemotherapy regimen, a combination of risk factors due to patient characteristics, or both. “However, many of the chemotherapy regimens used in clinical practice do not have an FN risk category in the guidelines,” the authors point out. With these patients, clinicians must rely on patient-related risk factors to guide their decision to prescribe G-CSF support.

“Most patients in the HM cohort of ZOHé had 2 to 3 patient-based risk factors for increased incidence of FN, which along with the ≥10% FN risk intrinsic to HM, most likely underlies the clinicians’ decision to prescribe primary prophylaxis,” they said. “The need for G-CSF support to maintain dose intensity in patients with HM who are given chemotherapy with curative intent could also underlie clinicians’ use of Zarzio.”