Both biologics and biosimilars are created in living cells. Biosimilars are drugs that are highly similar to an originator biologic that has already been approved by for use by regulatory bodies. This means that there cannot be any meaningful differences between the biosimilar and the reference drug with respect to effectiveness and safety. In order to establish biosimilarity, extensive analytical testing confirms matching of structure and function of the drug, followed by limited but targeted clinical trials in a patient population to demonstrate the same efficacy and safety. For approval of a biosimilar, it is not necessary to repeat studies in all the conditions for which the drug is used, as extrapolation is used for the other conditions for which the reference biologic is approved.