Biologics are all drugs in which the active substance is prepared with the use of living organisms. Obtaining a biological medicine entails a long and complicated process. However, it is worth investing in biologics because they imitate processes which occur naturally in the human body as closely as possible, thanks to which we can obtain an adequately strong reaction of the body while at the same time minimising the toxicity of the drug, and thus – achieve a therapeutic effect.
The first stage of developing a biologic is the identification of its molecular target, i.e. the target molecule in the body with which the drug is to interact. Identification and analysis of this molecule's structure allows the preliminary development of a compound which would potentially interact with it. Knowing the theoretical structure of the drug and using the tools offered by molecular biology makes it possible to develop a nucleotide sequence encoding the developed protein molecule. This sequence is inserted into the expression vector. Such a construct is then introduced into the host cell which will serve as the location where the biologic is created. The host is selected by considering characteristic features of the drug under development. Bacterial, yeast or mammalian cells can all act as the host for the production of biological drugs. A number of vital processes which are conditioned by other proteins take place in the host cell in addition to therapeutic protein synthesis. Hence, another challenge consists in the selection of cultivation conditions determining the highest-level expression of the gene which codes for the desired protein. Despite of established cultivation conditions, it is impossible to eliminate synthesis of other proteins in the host cell. Therefore after cells are cultivated, a mixture of various compounds is obtained. The objective of the subsequent stages of the process is to isolate the desired protein, and thus to purify the compounds which may be created after cell cultivation, such as host proteins, host cell DNA or the culture medium. To that end, several stages of protein purification with the use of filtration and chromatographic methods are applied. To ensure drug safety, it is crucial to obtain high-purity protein. Hence purity of the obtained protein as well as its quality and biological activity are controlled at every stage. One of the last steps in the process of obtaining a biologic drug is selecting the product's additional ingredients which will ensure stability of the therapeutic protein with simultaneous lack of negative impact on the patient.