Biosimilars Important in Management of Neutropenia

The potential of biosimiliars of granulocyte colony stimulating factor (G-CSF) to be important in the management of neutropenia has been supported by a recent analysis published in Biologics: Target and Therapy.

The analysis, with evidence compiled by researchers from the University Hospital of Verona in Italy, reviewed both biologic and economic factors of using G-CSF biosimilars to treat neutropenia that may affect post-chemotherapy and post-op patients.

Neutropenia can manifest as a low neutrophil count or high fever, as a result of infections that patients contract after specific treatments. G-CSFs, biological growth factors that promote the proliferation, differentiation, and activation of neutrophils in the bone marrow, have long been used to boost the number of circulating neutrophils in a patient either prior to or during treatment. This would allow a patient to start with a higher amount of neutrophils to compensate for the ones that would be lost as a result of the treatment.

The strategy of use includes using the G-CSF as “primary” prophylaxis (prevention) to reduce the risk of developing fever when the risk is over 20% likelihood. Evidence from multiple randomized trials and meta-analyses also support the benefit of primary prophylaxis in reducing the frequency of hospitalization for antibiotic therapy and documented infection. There is less evidence supporting G-CSF use as secondary prophylaxis (when the patient had a neutropenic fever in a previous course of chemotherapy and is expected to do so again) or as an adjunct to an antibiotic regimen.

Currently, the most commonly used type of G-CSF is filgrastim. The patent for filgrastim expired in 2006 in Europe and in 2013 in the US, and since then, the efficacy and safety of using a biosimilar has been a topic of interest in clinical practice. The biosimilar licensure pathway is part of an effort to encourage competition and thus keep drug prices low.

Results from studies conducted by several centers around the world have shown the benefit of biosimilars in stem cell transplant in neutropenic patients. Other trials have confirmed the bioequivalence of biosimilar G-CSF and their originator products. The European Medicines Agency has approved 16 G-CSF biosimilars since 2008, 3 of which are commercially available. The US approved Zarxio, a filgrastim biosimilar, in March 2015.

Aside from efficacy and safety, the review also found that prophylaxis or treatment of neutropenia with biosimilars is cost efficient. Biosimilars can play “an important role by offering the opportunity to reduce costs, thus contributing to the financial sustainability of treatment programs,” analysts wrote.