Real-World Data Reaffirm Biosimilar Filgrastim's Safety and Efficacy

Patients who have severe chronic neutropenia, a rare groups of blood disorders that involve long periods of low levels of neutrophils, have benefitted from treatment with granulocyte colony-stimulating factor (G-CSF) therapies since their introduction in 1987.

During the 24th European Hematology Association (EHA) Congress, researchers from the European branch of the Severe Chronic Neutropenia International Registry reported on experience with reference G-CSF products—including filgrastim (Neupogen), pegfilgrastim (Neulasta), and lenograstim (Granocyte)—and a biosimilar filgrastim (Zarzio, also sold in Europe as Filgrastim Hexal).¹

According to the investigators, 789 patients with severe chronic neutropenia—including congenital, cyclic, idiopathic, autoimmune, and other neutropenia—were enrolled in the European registry between 2011 and 2018, and 578 of them received G-CSF therapy.

Among these patients, 21 had received the biosimilar, and 16 of this group had switched from another G-CCSF product. Median treatment duration was 1.5 years (range, 0.1-4.4) and the median dose was 2.27 μg per kg per day (range, 0.25-40.0). Absolute neutrophil counts (ANC) during treatment showed that all patients responded well to the biosimilar, say the investigators, and ANCs were stable in patients who switched to the biosimilar from a branded drug.

Of the patients who received any G-CSF, 50 developed leukemia secondary to neutropenia. Only 1 of these patients had received the biosimilar. No cases of osteoporosis, severe splenomegaly, splenic rupture, severe side effects, or immunogenicity have been reported in patients who received the biosimilar.

In addition to the data presented on the biosimilar in the context of chronic neutropenia, the EHA congress also featured the presentation of data on the past decade of experience with the biosimilar.²

The authors of a narrative review of the evidence on Zarzio noted that post-approval studies have provided further evidence of the efficacy and safety of the biosimilar, particularly in the case of MONITOR-GCSF, which demonstrated, in sub-analyses, the efficacy and safety profile of the biosimilar in the prophylaxis of neutropenia in patients with multiple different tumor types.

In addition, data from studies of autologous stem cell mobilization show that the biosimilar is as safe and effective as the reference filgrastim, the authors note, and evidence is also accruing in the area of allogenic stem cell mobilization.

According to the review’s authors, the past 10 years of experience with the biosimilar, including 21 million patient days of exposure, show that the extrapolation of indications for biosimilars is based on strong scientific evidence and principles.

References

1. Zeidler C, Mellor-Heineke S, Nakov R, Natek M, Mathieson N, Gattu S. Patient with severe chronic neutropenia subtypes treated with biosimilar filgrastim: a study by the European branch of the severe chronic neutropenia international registry. Presented at: the 24th European Hematology Association Congress; June 13-16, 2019; Amsterdam, the Netherlands. Abstract PF353.

2. Gascón P, Mathieson N, Natek M, Krendyukov A, Aapro M. Ten years of clinical experience with biosimilar filgrastim in oncology and haematology. Presented at: the 24th European Hematology Association Congress; June 13-16, 2019; Amsterdam, the Netherlands. Abstract PF723.