Safety of Marketed Cancer Supportive Care Biosimilars in the US: A Disproportionality Analysis Using the Food and Drug Administration Adverse Event Reporting System (FAERS) Database.

Background: Since the approval and availability of the first biosimilar in 2015 in the United States (US), evidence regarding the post-marketing safety of cancer supportive care biosimilars remains limited.

Objective: The aim was to explore the adverse event (AE) reporting patterns and detect disproportionate reporting signals for cancer supportive care biosimilars in the US compared to their originator biologics.

Methods: The US Food and Drug Administration Adverse Event Reporting System database (January 1, 2004-March 31, 2020) was used to identify AE reports for filgrastim, pegfilgrastim, and epoetin alpha by type of product (originator biologics vs. biosimilars) and report characteristics. Plots of AE reports against years were used to reveal the reporting patterns. Disproportionality analyses using reporting odds ratios (RORs) were conducted to detect differences in serious and specific AEs between studied drugs and all other drugs. Breslow-Day tests were used to determine homogeneity between the originator biologic-biosimilar pair RORs for the same AE.

Results: Total numbers of AEs for all studied biosimilars increased after marketing. More AE reports were from female patients for all of the studied drugs. More AEs for originator biologics and filgrastim biosimilar were reported by health professionals, while the highest proportion of reports came from consumers for pegfilgrastim and epoetin alpha biosimilars (29% and 44.1%, respectively). Signals of disproportionate reporting in serious AEs were detected for a pegfilgrastim biosimilar (Fulphila) compared to its originator biologic.

Conclusion: Our findings support the similarity in the signals of disproportionate reporting between cancer supportive care originator biologics and biosimilars, except for Fulphila.