A robust and versatile nanobody platform for drug delivery

Therapeutic and diagnostic efficacies of numerous small biomolecules and chemical compounds are hampered by the short half-lives. Here we report the development of a repertoire of diverse, high-affinity albumin-nanobodies (NbHSA) to facilitate drug delivery. By integrating biophysics, and hybrid structural biology, we have systematically characterized the NbHSA for albumin binding, mapped the epitopes, and resolved the architecture of a tetrameric Nb-albumin complex. We employed quantitative proteomics for accurate, multiplex Nb pharmacokinetic analysis. Using a humanized albumin mouse model, we found that the NbHSA has outstanding pharmacokinetics; the most stable NbHSA has a 771-fold T1/2 improvement compared with a control Nb. Interestingly, the pharmacokinetics of NbHSA is related to their biophysical and structural properties. To demonstrate the utility of NbHSA, we developed a highly stable NbHSA-hIL-2 cytokine conjugate "Duraleukin" and confirmed its improved anticancer properties than hIL-2 alone. We envision that this high-quality Nb resource will advance research into novel biotherapeutics.