A resource of high-quality and versatile nanobodies for drug delivery

Therapeutic and diagnostic efficacies of small biomolecules and chemical compounds are hampered by suboptimal pharmacokinetics. Here, we developed a repertoire of robust and high-affinity antihuman serum albumin nanobodies (Nb-HSA) that can be readily fused to small biologics for half-life extension. We characterized the thermostability, binding kinetics, and cross-species reactivity of Nb(HSA)s, mapped their epitopes, and structurally resolved a tetrameric HSA-Nb complex. We parallelly determined the half-lives of a cohort of selected Nb(HSA)s in an HSA mouse model by quantitative proteomics. Compared to short-lived control nanobodies, the half-lives of Nb(HSA)s were drastically prolonged by 771-fold. Nb(HSA)s have distinct and diverse pharmacokinetics, positively correlating with their albumin binding affinities at the endosomal pH. We then generated stable and highly bioactive Nb-HSA-cytokine fusion constructs Duraleukin'' and demonstrated Duraleukin's high preclinical efficacy for cancer treatment in a melanoma model. This high-quality and versatile Nb toolkit will help tailor drug half-life to specific medical needs.

Automated summary

Researchers developed a Nb-HSA nanobody that can be fused to small biologics to extend half-life, significantly prolonging the half-lives of Nb(HSA)s and finding that their pharmacokinetics positively correlate with their albumin binding affinities at endosomal pH.