Circle Pharma is a biotech company that designs and develops macrocyclic peptide therapeutics for important clinical targets, particularly intracellular protein-protein interactions in cancer. They use a computational structure-based design approach that combines physics, chemistry, and biology. Circle has received funding from Pfizer, Mission Bay Capital, ShangPharma, The Column Group, and NextTech Invest. They utilize proprietary algorithms to design large libraries of cell permeable macrocyclic scaffolds and test candidate compounds for permeability and target affinity.