Techniques for predicting, detecting and reducing aspecific protein interference in assays involving immunoglobulin single variable domains
This invention provides, and in certain specific but non-limiting aspects relates to: assays that can be used to predict whether a given ISV will be subject to protein interference as described herein and/or give rise to an (aspecific) signal in such an assay (such as for example in an ADA immunoassay). Such predictive assays could for example be used to test whether a given ISV could have a tendency to give rise to such protein interference and/or such a signal; to select ISV's that are not or less prone to such protein interference or to giving such a signal; as an assay or test that can be used to test whether certain modification(s) to an ISV will (fully or partially) reduce its tendency to give rise to such interference or such a signal; and/or as an assay or test that can be used to guide modification or improvement of an ISV so as to reduce its tendency to give rise to such protein interference or signal; methods for modifying and/or improving ISV's to as to remove or reduce their tendency to give rise to such protein interference or such a signal; modifications that can be introduced into an ISV that remove or reduce its tendency to give rise to such protein interference or such a signal; ISV's that have been specifically selected (for example, using the assay(s) described herein) to have no or low(er)/reduced tendency to give rise to such protein interference or such a signal; modified and/or improved ISV's that have no or a low(er)/reduced tendency to give rise to such protein interference or such a signal.
1. A fusion protein comprising:
at least two heavy chain variable domains (VH or VHH), wherein at least one of the at least two heavy chain variable domains (VH or VHH) binds serum albumin and the remaining of the at least two heavy chain variable domains (VH or VHH) bind(s) a therapeutic target; and
one of the at least two heavy chain variable domains (VH or VHH) is at the C-terminal end of the fusion protein,
wherein the heavy chain variable domain (VH or VHH) at the C-terminal end of the fusion protein binds serum albumin and terminates in the sequence VTVSS(X) n (SEQ ID NO: 34, wherein: (i) n=1 or 2 in which each X is independently chosen from glycine (G), valine (V), leucine (L) or isoleucine (I); or (ii) n=3, 4 or 5 in which each X is independently chosen from alanine (A), glycine (G), valine (V), leucine (L), or isoleucine (I).
2. The fusion protein according to claim 1 , in which:
(a) n=1, 2 or 3 in which each X=Gly; or
(b) n=3 in which each X=Ala.
3. The fusion protein according to claim 1 , in which said VH is a camelized VH or wherein said VHH is a humanized VHH.
4. Pharmaceutical composition that comprises a fusion protein according to claim 1 , and at least one suitable carrier, diluent or excipient.
5. A fusion protein comprising:
at least two heavy chain variable domains (VH or VHH), wherein at least one of the at least two heavy chain variable domains (VH or VHH) binds serum albumin and the remaining of the at least two heavy chain variable domains (VH or VHH) bind(s) a therapeutic target; and
one of the at least two heavy chain variable domains (VH or VHH) is at the C-terminal end of the fusion protein,
wherein the heavy chain variable domain (VH or VHH) at the C-terminal end of the fusion protein binds serum albumin and terminates in the sequence VTVSS(X) n (SEQ ID NO: 34, in which:
(a) n=1 or 2 and each X is chosen from any naturally occurring amino acid except cysteine (C) or alanine (A); or
(b) n=3, 4 or 5 and each X is independently chosen from any naturally occurring amino acid except cysteine (C).
6. The fusion protein according to claim 5 , wherein n=3, 4 or 5 in which each X is independently chosen from the group consisting of alanine (A), glycine (G), valine (V), leucine (L) and isoleucine (I).
7. The fusion protein according to claim 5 , in which said VH is a camelized VH or wherein said VHH is a humanized VHH.
8. The fusion protein according to claim 5 , wherein n=1 or 2 in which each X is independently chosen from glycine (G), valine (V), leucine (L) or isoleucine (I).
9. Pharmaceutical composition that comprises a fusion protein according to claim 5 , and at least one suitable carrier, diluent or excipient.