Biosimilar Filgrastim Performs in Stem Cell Mobilization

In 2016, the Saskatchewan Cancer Agency switched from the brand-name filgrastim, Neupogen, to a biosimilar, Apotex’s Grastofil, for stem cell mobilization prior to autologous stem cell transplants (ASCT).

In a study presented at the American Society of Hematology’s Annual Meeting, held from December 1 to 4, 2018, in San Diego, California, researchers sought to determine the safety and efficacy of using a biosimilar for this setting.

In order to analyze the efficacy of the 2 products, the study’s authors reviewed patient charts and compared the efficacy of CD34+ collection in 170 patients who received the brand-name filgrastim with 47 patients who received the biosimilar between 2012 and 2018.

They found that the brand-name and the biosimilar demonstrated similar efficacy for stem cell mobilization, as 92.4% of the patients treated with the brand name had a successful harvest (as defined as a collection of 2x10⁶ or more CD34+ cells for patients planned for 1 stem cell transplant and 4x10⁶ or more CD34+ cells for patients planned for 2 transplants) compared with 100% of the patients taking the biosimilar.

In addition, the study’s authors also looked at the efficacy of mobilization with both filgrastim products, either alone or in combination with chemotherapy, in patients requiring more than 1 apheresis day and requiring the stem cell—stimulating agent, plerixafor. Clinical efficacy was defined in this portion of the study by using time to engraftment and length of hospital stay post-ASCT as parameters.

Importantly, the 2 products did not demonstrate a statistically significant difference in plerixafor requirement when patients had a low CD34+ count. There was also no statistically significant difference between each patient group that required more than 1 day of apheresis. In total, 59.4% of patients mobilized with the branded product required more than 1 apheresis day compared with 76.9% of patients mobilized with the biosimilar (P = .11).

Similarly, the researchers found that 42.5% of patients in the reference product group received chemotherapy, as compared with 38.1% in the biosimilar group, a difference that was not statistically significant (P = .71).

In analyzing differences in length of hospital stay for patients, the researchers found that, again, there was no statistically significant difference. In patients taking the reference without chemotherapy, the median length of stay was 18.5 days (interquartile range [IQR], 17.0-21.0) compared with 19.0 days (IQR, 17.0-22.0) for patients taking the biosimilar without chemotherapy (P = .10). For patients also taking chemotherapy, lengths of hospital stays increased, but not in a statistically significant manner.

Based on these findings, the researchers determined that, when using either the biosimilar or the reference product for ASCT, each medication has similar efficacy. The study authors concluded that, due to the similar efficacy, prescribing a biosimilar over a reference product would be able to “provide substantial cost savings to the healthcare system.”

Reference

Stakiw J, Sabry W, Elemary M, et al. Biosimilar G-CSF versus originator G-CSF for autologous peripheral blood stem cell mobilization: a comparative analysis of mobilization and engraftment. Presented at the 60th Annual Meeting and Exposition of the American Society of Hematology, December 1-4, 2018; San Diego, California. Abstract 3345. ash.confex.com/ash/2018/webprogram/Paper115341.html.