Stabilized single domain antibodies

Abstract

The present invention relates to heterospecific polypeptide constructs comprising at least one single domain antibody directed against a therapeutic and / or diagnostic target and at least one single domain antibody directed against a serum protein, said construct having a prolonged lifetime in biological circulatory systems. The invention further relates to methods for stabilising VHHs in biological circulatory systems.

Description

FIELD OF THE INVENTION [0001] The present invention provides heterospecific polypeptide constructs comprising one or more single domain antibodies, said constructs having improved stability in vivo and their use in diagnosis and therapy. BACKGROUND OF THE INVENTION [0002] Polypeptide therapeutics and in particular antibody-based therapeutics have significant potential as drugs because they have exquisite specificity to their target and a low inherent toxicity. However, in order to be effective as therapeutic agent, their pharmacokinetic profile should be optimized. The majority of current antibody applications are for acute disorders. There are however significant opportunities to develop antibody therapeutics for chronic conditions. This will require large doses of protein over a long period of time. Since the cost of antibody production in mammalian cells is high, the development of traditional antibody therapeutics for these applications has been discouraged. An alternative appro...

AI Technical Summary

Benefits of technology

[0069] One embodiment of the present invention is a polypeptide construct as described above, or a nucleic acid as described above for use in treating, preventing and / or alleviating the symptoms of a disease requiring a therapeutic or diagnostic compound which remains active in the circulation for extended periods of time.

[0077] One embodiment of the present invention is a method for prolonging the half-life of a single domain antibody in the blood stream of a subject, said antibody directed against a therapeutic and / or diagnostic target by joining thereto one or more single domain antibodies directed against a serum protein.

Problems solved by technology

This will require large doses of protein over a long period of time.

Since the cost of antibody production in mammalian cells is high, the development of traditional antibody therapeutics for these applications has been discouraged.

Such chemical methods, however, suffer from a number of disadvantages, such as inactivation of the target protein or peptide due to the chemical modification of certain amino acid side chains, instability of the target protein / peptide during the chemical reaction.

The drawback of these peptide-based approaches is that the peptides have to fold properly and be accessible to binding to serum albumin when fused to the therapeutic protein.

Therefore, these peptides are inherently unstable and have affinities in the submicromolar range rather than subnanomolar or low nanomolar range, as is the case with conventional antibodies.

However, such heterospecific constructs based on conventional antibodies or Fab fragments have several important drawbacks: these are complex, large molecules composed of two polypeptide chains (VH and VL) and therefore difficult and expensive to produce in high amounts in mammalian expression systems.

Furthermore, producing bifunctional antibodies composed of 4 chains (2 VH's and 2 VL's) have the inherent risk of resulting in molecules with the unproductive VH-VL combinations and consequent loss of activity.

Diabodies are known to be inherently difficult to produce due to stickiness of their exposed surface and due to non-productive associations between the four different V-regions (2 VH+2 VL).

Covalent binding to serum proteins as disdosed in, for example, EP0793506B1, U.S. Pat. Nos. 5,612,034, 6,103,233, and US20020009441 using reactive groups forming stable covalent bonds to a serum protein or a cell have the inherent disadvantage of unwanted target modification through the reactive groups.

Such fusions have the disadvantage of inefficient production and causing unwanted immunological reactions.

Such approach has the inherent risk of impairing the biological activity of the interferon since the size of the construct raises the problem of steric hindrance.

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