XL-protein is a privately owned German biotech company commercializing the PASylation technology, which allows the extension of the plasma half-life of biopharmaceuticals. XL-protein focuses on the preclinical and clinical development of PASylated proteins in several disease areas. Its goal is to provide improved second-generation biopharma­ceuticals allowing less frequent and lower dosing together with better tolerability, making treatment cheaper and supporting patient compliance and safety.