Strict regulatory mechanisms are in place to ensure that biosimilar medicines are suitable for patients and accessible by their HCPs. The concept of extrapolation is based on stringent, scientifically validated procedures.1 But what is extrapolation? When talking about biosimilars, extrapolation refers to the approval of a biosimilar for use in an indication held by the reference biologic not directly studied in a comparative clinical trial with the biosimilar. Extrapolation is only feasible once biosimilarity has been proven in a sensitive study population. In other words, to get the same indication of a reference product, we can take existing data without having to complete a whole new randomized controlled trial (RCT) against the originator product to prove the indication. Interestingly, this concept of extrapolation was already happening historically in the EU, particularly with CMC – Chemistry, Manufacturing, and Controls.2 This is something rarely discussed.2 In other words, we are using this concept to help replicate good practices in biologics manufacturing. Why reinvent the wheel every time if we do not need to?