Biosimilars in dermatology: identifying myths and knowledge gaps.

Biosimilars are beginning to gain regulatory approval in the United States. Biosimilars are structurally near identical to the innovator and must demonstrate identical pharmacokinetics via the same binding affinity and biological function on assays. However, biologics are so complex that even the innovator company cannot produce exact duplicates; there is batch-to-batch variation. The International Psoriasis Council has outlined a biosimilarity index, which aims to standardize preclinical definitions of biosimilarity. Such an index, paired with post-approval monitoring, could provide a transparent, quantitative definition of biosimilarity. Such an index could increase trust in biosimilar medicines and the preclinical assessment process without increasing costs. As preclinical analyses are critical to biosimilar approval, manufacturers should devote proportionate resources to completing them. Dermatologists, who might reflexively look for indication-specific clinical data, might also shift their focus to preclinical variables. Finally, it should be noted that biosimilars provide more evidence of similarity than we have for different batches of the innovator product. Thus, any clinical testing standards, or lack thereof, for different batches of innovator products should also apply to biosimilars.