[Development of New Biologics through Creation of a Functional Cytokine Mutant]

The clinical use of cytokines is fairly limited because of their characteristics of having significant bioactivity and low stability, although some are useful biopharmaceuticals, such as interferon. Cytokines, which are secreted from various immune cells, show many kinds of bioactivities including unexpected activities; thus it would be desirable to regulate cytokine activity. Recently, we have developed a new drug delivery system (DDS) to create structural mutant cytokines using a phage display system. This system can produce functional mutant proteins that can bind their objective targets specifically. In this study, tumor necrosis factor (TNF) was used as a model cytokine to create agonist and antagonist activities against two TNF receptors TNFR1 and TNFR2, respectively. We created a phage library expressing mutant TNF, where the amino acids in the binding interface between TNF and TNF receptors were alternately exchanged. Affinity panning was performed at the optimum condition and the bioactivities of these mutant TNFs were analyzed to obtain the objective agonists or antagonists. The pharmacological activity and toxicity of these engineered TNF mutants could indicate their potential use as novel biopharmaceutical agents.