Compared with its reference product, a does not need to be taken through the discovery stage and phase II clinical stage, meaning the cost is quite reduced. However, it is not an easy thing to develop and manufacture biosimilars. Unlike generics manufactured simply by chemical synthesis, biosimilars are produced from living cells due to their larger size and more complex structures. Since some of the manufacturing details of the reference product are not disclosed, the biosimilar manufacturers have to develop their own cell clones and manufacturing processes.