Biosimilars: Illustration of scientific issues in two examples

Purpose. Scientific issues and clinical implications associated with the use of biosimilars (biopharmaceuticals that are similar to an innovator product, notwithstanding minor differences) are illustrated in two examples, botulinum neurotoxins and erythropoietic agents. Summary. Comparison of Botox and Dysport, products that both contain botulinum toxin type A, revealed distinct differences in physicochemical characteristics, approved indications, dosing,. and frequency of adverse events. Differentiating between botulinum toxin products on the basis of immunogenicity in the clinical setting would be of value in product selection, and pharmacists could play a valuable role in collecting antigenicity rate data and reporting them to the Food and Drug Administration (FDA) and the manufacturer. Various ethical and practical considerations are associated with the use of erythropoietic agents. The desire to optimize patient care and outcomes must be weighed against,the likelihood of obtaining reimbursement for erythropoietic therapy, and reimbursement policies vary from one state to another. Comparing erythropoietic agents requires the use of a consistent and valid definition of treatment response. The definition of response that FDA will accept in the future when evaluating applications for approval of new biosimilar erythropoietic agents and establishing equivalence remains to be determined. Conclusion. A variety of scientific and practical clinical issues are associated with the use of biosimilars, including product differences in physicochemical characteristics, reimbursement policies, and the need for valid and clinically relevant criteria for comparing the efficacy and safety of biosimilars and innovator products.