Circle Pharma initiated operations in June 2014 with seed funding from Pfizer, Inc. and Mission Bay Capital, LLP; we received additional seed funding from ShangPharma Investment Group Limited in November 2015. We recently raised Series B and Series C financing from The Column Group and NextTech Invest. We design and develop bioavailable macrocyclic peptide therapeutics against important clinical targets. We do this by applying a computational structure-based design approach that combines physics (conformational modeling), chemistry (innovative molecular components) and biology (protein target structure and function). We have selected intracellular protein-protein interactions that play key roles in cancer as the initial target group for our internal pipeline development. Circle is taking a new approach to the development of macrocylic peptide therapeutics that is based on the pioneering work of its founders to understand and computationally predict drug-like properties of macrocycles. Circle is advancing this understanding to design novel, inherently permeable macrocyclic peptide drug candidates against Circle’s internal targets and those of our collaboration partners. Our workflow includes the use of proprietary algorithms to design large, conformationally diverse, virtual libraries of cell permeable macrocyclic scaffolds that incorporate natural and non-natural backbone components. We deploy these virtual scaffold libraries in subsequent design steps that include the incorporation of functional side chains selected for both target binding and maintenance of permeability. Candidate compounds are synthesized and tested for both permeability and target affinity and the results are used to inform subsequent design cycles.