Centyrins are small, engineered proteins derived from a human protein, Tenascin C, found in the extracellular matrix of various tissues. The Centyrin framework was selected to confer exceptional stability and biophysical properties, an important consideration in the context of effective delivery of therapeutics within the intracellular environment. By varying amino acids within select regions of the Centyrin framework, we have created libraries containing trillions of Centyrin variants and can rapidly identify Centyrin clones that bind with high specificity and affinity against antigens of interest. We have also mapped the Centyrin framework to identify specific amino acid residues where we can chemically conjugate drug payloads, without affecting the underlying stability, solubility or antigen binding properties of the Centyrin. To achieve cell specific drug delivery, we select Centyrins that are specific for cell surface receptors in mono, bi or multi specifics formats as needed to optimize binding and internalization of conjugated drug payloads such as oligonucleotides. Aro has exclusive rights to the extensive Centyrin IP portfolio.