Abstract
Nanobodies are antigen-binding, single variable domain proteins derived from naturally-occurring, heavy chain only antibodies. They are highly soluble, stable, and can be linked to build multi-specific formats. Several Nanobodies are currently in clinical development in different therapeutic areas, for both chronic and acute applications. For the former, prolonged exposure is achieved by half-life extending moieties that target endogenous albumin, while for the latter, non-half-life extended constructs are preferable. To demonstrate the general pharmacokinetic behavior of both formats, serum levels of seven intravenously administered Nanobodies were analyzed in cynomolgus monkeys, mice or rabbits. In monkeys, the total clearance of a monomeric irrelevant Nanobody was rapid (2.0 mL/(min*kg)) and approximated the species glomerular filtration rate, indirectly suggesting that the Nanobody was mainly eliminated via the kidneys. When linked to an anti-albumin Nanobody, a 376-fold decrease in clearance was observed, resulting in a terminal half-life of 4.9 days, corresponding to the expected species albumin half-life. Similar conclusions were drawn for (non-) half-life extended mono-, bi- and trimeric Nanobodies in mice or rabbits, suggesting that these kinetic principles apply across species. Applying this knowledge to species translation and study design is crucial for successful pre-clinical development of novel therapeutic Nanobody candidates.
Highlights
Nanobodies are antigen-binding, single variable domain proteins derived from naturally-occurring heavy chain only antibodies [1]
Following a single i.v. bolus administration, the serum PK of seven Nanobodies composed of varying constructs of a combination of irrelevant (‘Irr’: no target binding) and albumin binding (‘Hle’: Half-life extension) building blocks, were evaluated in mice, rabbits or cynomolgus monkeys
The estimated clearance drastically increased (48-fold), with corresponding decrease in area under the curve (AUC) (48-fold decrease in dose normalized AUC), when Irr2-Hle2-Irr2 was administered to rabbits (i.v. 2.5 mg/kg) compared with mice (i.v. 1.2 mg/kg), as Hle2 binds strongly to mouse albumin but not to rabbit albumin. These results clearly indicate that half-life extension via anti-albumin binding proved successful in decreasing the total Nanobody clearance resulting in prolonged exposure in terms of estimated AUC and measurable serum levels in mice and monkeys, as shown by a set of different
Summary
Nanobodies are antigen-binding, single variable domain proteins derived from naturally-occurring heavy chain only antibodies [1]. The single domain nature and small size allow easy formatting by genetic fusion into multimeric constructs with multiple specificities [2,3]. Owing to these favorable properties, several Nanobodies are being developed for a wide variety of therapeutic applications [4,5]. Small proteins are expected to be filtered by the renal glomerulus. The sieving coefficient at which albumin is filtered through the glomerulus is small, estimated at 0.062% [10,11] to 0.19% in rats [12]. Proteins of similar size, such as nartograstim (19 kDa) and filgrastim (19 kDa) have been reported to be extensively cleared by renal excretion in rats [13,14]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
