OBJECTIVES: Cost of cancer treatment in the United States is expected to be more than $174 billion annually in 2020. Recently, there has been an increase in the production of biologic products for cancer that stimulate the body’s immune system to combat cancer cells. Nevertheless, long-term data for the use of biologics and biosimilars are limited, in which challenges are created in assessing the safety of these biotherapeutics. This study evaluated the reports of adverse events of biologics and biosimilars reported to the FDA Adverse Event Reporting System (FAERS) during the period of January 1, 1999, through September 30, 2019.

METHODS: A retrospective analysis was conducted on oncology data publicly available through FAERS. Reporting odds ratios (RORs) and 95% confidence intervals (CI) were used to identify signals of disproportionate reporting in adverse reactions among biologics used in oncology along with disproportionate signals were assessed.

RESULTS: Disproportionality reporting signals were detected for serious adverse events among patients using interferon alfa-2a (ROR [95%CI] =26.63 [12.79, 55.42]), interferon beta-1a (ROR [95%CI] =2.24 [2.10, 2.38]), interferon beta-1b (ROR [95%CI] =3.16 [2.94, 3.40]). In monoclonal antibodies products, disproportionality signals were found for the occurrence of serious adverse events in patients using alemtuzumab (ROR [95%CI] = 2.92 [2.61-3.27]), atezolizumab (ROR [95%CI] = 1.55 [1.33-1.80]), and bevacizumab (ROR [95%CI] = 2.94 [2.76-3.12]).

CONCLUSIONS: This study identified disproportionate reporting signals of safety associated with biologics and biosimilars used in oncology. Evaluation of long-term clinical effects and risks, including immunological complications, is needed due to the growing interest in early initiation of biologics in cancer treatment. While causal inferences cannot be determined through use of signals identified from voluntary reporting systems, analysis of FAERS is a valuable part of the ongoing surveillance of the safety and efficacy of biologics in clinical practice.