Granulocyte colony-stimulating factor (G-CSF) can be used to mobilize peripheral blood stem cells (PBSCs) in healthy donors. Over the last 10 years, the procedure has become the preferred option for donors compared to the donation of bone marrow.
Donation of PBSCs is performed to re-establish haematopoietic function in patients whose bone marrow or immune system is damaged or defective, such as in patients with multiple myeloma or leukaemia.
The first biosimilar G-CSF was licensed by EMA in 2008, and there are currently six biosimilar G-CSF products licensed for use in the EU. All of these biosimilars are also approved for haematopoietic stem cell transplantation.
Several organizations, including the World Marrow Donor Association (WMDA), the European Group for Blood and Marrow Transplantation (EBMT), the Austrian Society of Hematology Oncology (ASHO) and the Società Italiana di Emaferesi e Manipolazione Cellulare (SIdEM), have however expressed their reservations over the use of G-CSF biosimilars in healthy donors.
The reasons for their caution relate to the fact that all the G-CSF biosimilars approved in Europe were authorized for this indication by extrapolation. The groups are also concerned about ‘an absence of published experience in the field’.
EMA, however, has stated that extrapolation of data to other indications of the reference biological – and thus formal lack of a clinical trial in the respective clinical indication – does not imply less reassurance as regards to efficacy and safety of the biosimilar. For extrapolation of data to be considered, the biosimilar must show convincing evidence of similarity with the reference product, based on a thorough comparability exercise. Only if clinical similarity can be shown in a key indication, may extrapolation of efficacy and safety data to other indication(s) of the reference product be possible. All of this is also based on the fact that the safety profile of the biosimilar has been properly characterized and unacceptable immunogenicity excluded.
Although Alberto Bosi claims that ‘no evidence definitely supports safety and efficacy of G-CSF biosimilars for [stem cell] mobilization in healthy donors’; evidence does exist. A recent study of mobilization of PBSCs in healthy donors found a lack of significant differences between the biosimilar G‑CSFs tested (Biograstim, Ratiograstim or Tevagrastim) versus the brand-name reference G-CSF (Neupogen). The authors concluded that their study clearly demonstrated the ‘similarity’ of the biosimilars in terms of both efficacy and safety for this indication.
Conflict of interest
The author of the research paper did not declare any conflict of interest.
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