Discovery and Characterization of Inhibitors of Protein/Protein Interactions by ITC.

The inhibition of protein-protein interactions is a major goal in the therapy of different pathological conditions including cancer, inflammation, autoimmune diseases, diabetes, osteoporosis, infection, etc. Since protein-protein interactions play a critical role in biological signaling, the identification and optimization of molecules that inhibit those interactions is a major research objective in the pharmaceutical industry. The number of targets of interest is continuously increasing and range from a vast number of cell surface receptors, such as EGFr, TNFr, and IGFr to other proteins involved in signaling and regulation (1, 2). In the case of HIV infection, for example, the first event is the binding of the viral envelope glycoprotein gp120 to the cell surface receptor CD4 (3, 4). Until now, biologics, i.e. monoclonal antibodies or recombinant versions of ligand proteins and/or soluble regions of the receptors, have defined the therapeutic arsenal aimed at targeting protein/protein interactions. The identification of small molecules that accomplish the same goals has become a new frontier in drug research.