Very small and extremely stable
Nanofitins® are small, single-chain proteins (7 kDa, around 20 times smaller than a monoclonal antibody) derived from a naturally hyperstable scaffold, from which they retain most of the biochemical features such as resistance to temperature (70-80°C) and pH (10-13) (Mouratou et al., Remodeling a DNA-binding protein as a specific in vivo inhibitor of bacterial secretin PulD, Proceedings of the National Academy of Science of the USA, 2007).
They are not stabilized by any disulphide bridge. Nanofitins® can be manufactured by simple, scalable, GMP-compliant bacterial fermentation at very attractive costs but full chemical synthesis is also possible.
Nanofitins® have demonstrated a very high protease resistance and can thus survive in gastric fluids, which enables development of orally formulated Nanofitins® for therapeutics applications. They can also be formulated in a large spectrum of buffers and be concentrated up to 300 mg/mL to reach very high doses in a small volume, making them compatible with nebulization and pulmonary delivery. The combination of these features make Nanofitins® highly druggable compounds.
Particularly fitted for combination
N-/C- termini are not involved in the binding site. Thus, Nanofitins® can be:
- Assembled in multimers for enhanced avidity or for multi-specificity (up to 5 Nanofitins®as one multivalent compound with retained individual affinity). In every instance, the binding property of each single Nanofitin® is not affected.
- Conjugated to other moieties (small molecules, proteins, antibodies, radionuclides, nucleic acids, T-cells…) by genetic fusion or click chemistry
- Easily tethered to a support for detection and capture (regioselective conjugation through insertion of one single Cysteine in the sequence)
Progressing toward clinical phases with a de-risked protein scaffold
Through the different pre-clinical stage programs currently developed by Affilogic, itself or with partners, the safety profile of the Nanofitins® has been found acceptable in regulatory-compliant toxicology analyses: no genotoxicity or cardiotoxicity, no mortality or clinical signs at a very high dose of 200 mg/kg, low immunogenicity of the Nanofitin® scaffold in a T-cell prediction model from 50 different donors and after rodent vaccination. As regards biodistribution, Nanofitins® injected systemically do not aggregate in kidneys and have a rapid bladder clearance, due to their short plasmatic half-life wich can be extended by fusion with another Nanofitin®.