Due to their small size and unique structure, Nanobodies are ideal building blocks for the generation of novel biological drugs with multiple advantages:
Ability to bind multiple targets with one therapeutic Nanobody molecule. These therapeutic molecules may contain Nanobody building blocks combined with each other (up to 7), or be combined with other protein domains or with other molecules or drugs.
Multi-specific (binding different targets; currently 2 bi-specific Nanobodies in the clinic), multivalent (binding identical targets; currently 2 Nanobodies in the clinic) and bi-paratopic (binding different epitopes on the same target) Nanobody molecules have been successfully produced and their potential therapeutic effect demonstrated. The different Nanobody building blocks are linked together with Glycine-Serine linkers with flexible lengths.
Nanobodies can interact with epitopes on targets which are hidden or shielded from the much larger conventional antibodies.Functional selective Nanobodies have been generated against GPCRs as well as ion-gated, ligand-gate and voltage-gated ion channels (multiple programmes on-going, both internally and with partners including Merck & Co., Novartis, and Genzyme).
The robustness and stability of Nanobodies allows administration through multiple delivery routes, including intravenous and subcutaneous injection (currently 5 Nanobodies in the clinic)and nebulisation directly into the respiratory tract (currently 1 Nanobody in the clinic), as well as potentially through the ocular route and orally for local treatment in the gut.
Ability to tailor the in vivo half-life of a Nanobody from a few hours to >3 weeksto achieve the desired properties, such as the use in chronic versus acute indications. Ablynx’s proprietary half-life extension technology is based on a Nanobody that binds to human serum albumin, thereby increasing the in vivo serum half-life of the therapeutic molecule.
Two clinical proof-of-concepts have been achieved in patients with rheumatoid arthritis with two Nanobodies that incorporate this proprietary half-life extension technology.
As a result of their formatting flexibility, specific Nanobody formats can be developed to increase cell specificity. For example, Nanobodies with low activity on normal cells can be linked to an anti-“anchor”-Nanobody resulting in avid binding on tumour cells, dramatically improving the potency of the Nanobody on tumour cells. The same principle can also be applied for localised treatment in certain tissues like the joints and the eye, using a tissue-specific anchor to ensure high local concentrations while minimising systemic exposure. Lastly, taking advantage of the ability of Nanobodies to be readily formatted into multi-specifics, we can design Nanobody drugs that result in improved tumour cell killing by recruiting immune cells to tumours.
Nanobodies can be applied in the field of antibody-drug conjugate technologies (ADC), which uses antibodies or antibody-derived molecules to deliver highly potent anticancer agents to cancer cells.
An ADC consists of a cell-killing agent which is covalently attached to a Nanobody that binds to a target antigen on cancer cells. In this case, the Nanobody serves to deliver the cell-killing agent specifically into the cancer cells where the cytotoxic is internalised and released to specifically kill the cancer cells.
Because of their simple structure and stability, Nanobodies can be easily coupled to cytotoxic compounds without losing any binding affinity, and yielding a uniform conjugate, whereas for antibodies the result can often be a mixture of antibodies with a varying number of warheads linked to it. In addition, the formatting flexibility of Nanobodies can be leveraged to combine different binding specificities into one drug to minimize killing of normal cells, or to target different receptors to enhance efficiency of uptake of the cytotoxic payload into tumour cells.
Nanobodies (including multi-specific, multivalent and bi-paratopic constructs) are encoded by single genes and are efficiently produced in various prokaryotic and eukaryotic hosts, including bacteria, yeast, and mammalian cells. They can be formulated at high concentrations and maintain low viscosity, enabling multiple routes of administration, including low volume injectables.
Mix and Match
Presentation: "Nanobodies as a Versatile Approach for Developing Next Generation Immunotherapies"
Poster presentation: by Boehringer Ingelheim: "Dual targeting of angiogenesis pathways: combined blockade of VEGF and Ang2 signalling"
Presentation: "Nanobodies as a versatile and clinically validated approach for multi-specific therapeutics"
Presentation: "Bi-specific Nanobodies with enhanced cell specificity"
Presentation: "Strategies and Challenges in Analytical Testing of Nanobody-Based Multi-specifics"
Cell- /tissue homing
Presentation: "The Nanobody platform: opportunity for next generation T-cell recruitment"
Challenging and intractable targets
Presentation: "Ion channel modulating Nanobodies - 2 in vitro and in vivo case studies"
Poster: "Characterization of anti-Kv1.3 Nanobodies and activity in inflammatory model systems"
Poster: "Formatting flexibility of Nanobodies is ideally suited for ion channels: Kv1.3 case study"
Presentation: "Nanobodies against difficult targets: Tackling ion channels”
Poster: "Development of highly potent and selective anti-Kv1.3 Nanobodies that operate through allosteric modulation"
Alternative delivery routes
Poster: "Non-clinical safety assessment of ALX-0171, anti-RSV Nanobody intended for clinical administration through inhalation"
Presentation: "Double digit-titers and high product quality of Nanobodies"