The Sequence Listing submitted herewith, entitled “Jan-11-2019-SEQ-LIST_ST25.TXT”, created Nov. 16, 2018, and having a size of 626 bytes, is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a brain delivery protein, which enables transportation of a protein, such as an antibody, which binds to a target in the brain, across the blood brain barrier.

BACKGROUND

The blood brain barrier (BBB) is comprised of tightly connected endothelial cells and serves as a protector of the brain by keeping both small drug-like molecules and larger molecules like proteins outside the brain. Although essential for brain homeostasis, the presence of this barrier is an obstacle to treatment and diagnostics of diseases in the brain. For example, only around 0.1% of unmodified antibodies enter the brain due to the tightly connected endothelial cells of the BBB (Bard F. et al, Nat. Med. 6: 916-919 (2000)).However, active transport from blood across the BBB into the brain has been described for some proteins. One such example is transferrin that transports iron to the brain via the transferrin receptor (TfR) located at the BBB. The transferrin-TfR complex is formed at the luminal side of the BBB and subsequently endocytosed. Iron dissociates from the transferrin in the endosomes where the pH is lower. Transferrin with no iron bound, apotransferrin, has a low affinity for the TfR and is released together with the iron at the abluminal side of the BBB. Not only transferrin but also other proteins that bind to the TfR can be endocytosed from the luminal to the abluminal side of the BBB and this mechanism can be exploited to actively transport molecules into the brain (Boado R J. et al, Biotechnol. Bioeng. 102: 1251-1258 (2009); Pardridge W M, Expert Opin. Drug Deliv. 12: 207-222 (2015)).To avoid degradation in the lysosomes, it is necessary that the protein/antibody binding to the TfR dissociates from the receptor in the endosome. It has been proposed that the dissociation from TfR can be facilitated by the low pH environment in the endosome for binders that display pH dependent affinity (Sade H. et al, PLOS one 4: e96340 (2014)). Dissociation is also more likely when the overall affinity to TfR is moderate or low (Yu Y J. et al, Sci. Transl. Med. 3: 84ra44 (2011)). Bivalent binding to the target has also been found to be disadvantageous (Niewoehner J. et al, Neuron 81: 49-60 (2014)). Antibody bivalent binding decreases the rate of dissociation from the TfR since antibody dissociation requires a simultaneous dissociation from two epitopes (binding sites) i.e. the avidity effectA bispecific protein consisting of an anti-amyloid β protofibril antibody, referred to as mAb158, chemically conjugated to a TfR antibody 8D3 has previously been disclosed (Sehlin D. et al, Nat. Commun. 7: 10759 (2016)). This protein displayed 20-fold higher brain-to-blood concentrations than mAb158 at 3 days post injection. The increased ratio was found to be partly due to increased brain concentration and partly due to a decreased half-life in blood compared with mAb158.An antibody with low affinity to a BBB receptor has previously been disclosed in WO 2012/075037. Moreover, this publication discloses differences observed in brain uptake for a bispecific antibody (anti-TfRA/BACE1) that binds both TfR and the amyloid precursor protein (APP) cleavage enzyme, beta secretase (BACE1), between administration at a trace dose and at a therapeutic dose.In WO 2014/033074 another variant of a BBB antibody shuttle is disclosed. The BBB shuttle comprises a brain effector entity, a linker and one monovalent binding entity which binds to TfR, wherein the linker couples the effector entity to the monovalent binding entity which binds to the TfR.In order to provide improved therapy and diagnosis of diseases in the brain, and for research purposes, there is still need for proteins/antibodies with improved uptake.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide novel proteins for treatment and diagnosis of diseases in the brain, as well as for research purposes.There is, in a first aspect of the invention, provided a brain delivery protein, comprisinga target binding antibody or fragment thereof which binds to a target in a mammalian brain;two carrier moieties, each of which being capable of monovalent interaction with a protein expressed on a blood brain barrier (BBB) endothelial cell,wherein each of said carrier moieties is linked to a C-terminal end of the target binding antibody.The brain delivery protein as disclosed herein comprises two types of moieties; a target binding antibody which binds to a target in the brain and two carrier moieties which enable transportation of the brain delivery protein across the BBB into the brain. Both carrier moieties are capable of monovalent interaction with, or monovalent binding to, a protein on a BBB endothelial cell. Monovalent interaction or binding indicates that the interaction between the carrier moiety and the protein expressed on a BBB endothelial cell takes place through one single epitope. Due to the structure of the brain delivery protein, typically only one of the carrier moieties at a time may bind to the protein expressed on the BBB. This may in turn prevent bivalent, high avidity binding to the BBB protein and lead to a more efficient BBB transfer, and may also prevent any dimerization/conformational change of the BBB protein.In one embodiment, one of said two carrier moieties binds at a time to said protein expressed on a BBB endothelial cell. Monovalent interaction of the brain delivery protein as such with the protein expressed on the BBB endothelial cell is thus enabled.Thus, by maintaining monovalent binding despite having two carrier moieties that potentially may bind to said BBB protein, the efficiency of transport across the BBB may be increased. By having two carrier moieties connected to the target binding antibody, the number of available binding sites to a protein expressed on BBB cells will be doubled compared to a brain delivery protein comprising only one carrier moiety. Dosing experiments conducted in mice moreover demonstrated that a brain delivery protein according to the present invention comprising two carrier moieties improves brain uptake at both therapeutic and trace doses (Example 2). The specific brain delivery protein studied in Example 2, RmAb158-scFv8D3, with two single chain TfR binding antibodies (scFv8D3), was found to increase brain uptake by approximately 80 times at 2 h post injection at trace dosing, compared to the brain uptake of a “naked” target binding antibody (RmAb158) without carrier moiety. Similar results have been obtained for RmAb48-scFv8D3 (Example 5). At therapeutic dosing the brain uptake of RmAb158-scFv8D3 was found to be 10 times higher than the brain uptake of the corresponding naked target binding antibody. It is hypothesized that this difference may, at least in part, depend on the brain delivery protein having two TfR binding moieties. By comparison, brain shuttles of the prior art have demonstrated approximately 40 times increased uptake of anti-TfR antibody at trace dosing, whereas brain uptake of the same shuttle at therapeutic doses is increased only 1.4 times (Yu et al, supra, (2011)). This might be due to the TfR system getting saturated at therapeutic doses. Similar results have however been previously published for a brain shuttle based on CD98 as a BBB shuttle. At trace dosing the uptake was found to be 80 times higher than antibody without CD98 but at therapeutic dosing it was only 3.2 times higher (Zuchero Y J Y. et al, Neuron 89: 70-82 (2016)).The carrier moieties of the brain delivery protein as disclosed herein are linked to the target binding antibody at a C-terminal end of the target binding antibody. The carrier moieties are preferably located at a C-terminal end of a heavy chain or at a light chain of the target binding antibody. Preferably, the carrier moieties are linked to separate chains of the target binding antibody, preferably to a separate light chain or to a separate heavy chain.According to one embodiment, each of said carrier moieties is linked to the target binding antibody by a linker. The linkers for connecting the carrier moieties to the target binding antibody may be the same or different, i.e. they may have identical length and/or amino acid sequences, or they may have different length and/or amino acid sequences. In particular, in respect of each of said carrier moieties, each of said linkers individually comprises a peptide having an amino acid sequence consisting of 1-30 amino acid residues, preferably 1-25 amino acid residues, preferably 1-19 amino acid residues, preferably 3-19 amino acid residues, preferably 3-15 amino acid residues, preferably 5-15 amino acid residues. One example of a linker is a linker having 11 amino acids. Such a linker length has been used in the appended examples. Thus, said linker is preferably a relatively short peptide. However, the length of the linker may be different depending on the specific position of the linker on the target binding antibody. A short linker may be advantageous in that the carrier moieties may be further sterically hindered to bivalently bind to a protein, e.g. a dimeric receptor, expressed on an endothelial BBB cell. Compared with bivalent binding, monovalent binding with a protein expressed on a BBB endothelial cell might provide improved transfer across the BBB. Bivalent binding decreases the rate of dissociation, which in turn may increase the probability of binding and hence the binding time, i.e. the avidity effect leading to reduced BBB transport.In one embodiment, each of said two carrier moieties is linked to a C-terminal end of a light chain of the target binding antibody. In particular, a brain delivery protein comprising two carrier moieties linked to said target binding antibody by short peptide linkers, e.g. each linker comprising a peptide having 1-30 amino acid residues, may still enable monovalent interaction with the protein expressed on BBB endothelial cells. For example, each linker may comprise a peptide having 1-25 amino acids, preferably 1-19 amino acids, more preferably 5-19 amino acids. A non-limiting example of a linker for linking each of the carrier moieties to the C-terminal ends of the light chains of the target binding antibody is a linker having a length of 11 amino acid residues. Such a linker is disclosed in the appended examples. It should be understood that the linkers for linking the carrier moieties with the target binding antibody could be identical or different, i.e. they may have identical length and/or amino acid sequences, or they may have different length and/or amino acid sequences.In one embodiment, each of said two carrier moieties is linked to a C-terminal end of a heavy chain of the target binding antibody. In particular, a brain delivery protein comprising two carrier moieties linked to said target binding antibody by short peptide linkers, e.g. each linker comprising a peptide having 1-19 amino acid residues, may still enable monovalent interaction with the protein expressed on BBB endothelial cells. For example, each linker may comprise a peptide having 1-19 amino acids, preferably 1-15 amino acids, more preferably 1-10 amino acids. It should be understood that the linkers linking the carrier moieties with the target binding antibody could be identical or different, i.e. they may have identical length and/or amino acid sequences, or they may have different length and/or amino acid sequences.In one embodiment, a first carrier moiety is linked to a C-terminal of a heavy chain of the target binding antibody, and a second carrier moiety is linked to a C-terminal end of a light chain of the target binding antibody. It should be understood that the linkers linking the carrier moieties with the target binding antibody could be identical or different, i.e. they may have identical length and/or amino acid sequences, or they may have different length and/or amino acid sequences. Example lengths of linkers are disclosed in related embodiments herein.As disclosed in the appended examples, a relatively short peptide linker, linking two carrier moieties (scFv8D3) to the C-terminal ends of the light chain of a target binding antibody (RmAb158), has been found to sterically hinder bivalent binding to the protein expressed on the BBB (TfR dimer). The peptide linker used in the appended examples was flexible and hydrophilic, and contained 11 amino acid residues. Thus, one non-limiting example of a linker that may be used in the brain delivery protein according to the present invention is a linker comprising a peptide having the amino acid sequence APGSYTGSAPG (SEQ ID NO:1). Peptide linkers having different lengths and amino acid sequences are also encompassed by the present disclosure. The skilled person would understand how to design alternative linker sequences, i.e. select alternative amino acid residues having/providing similar properties in terms of e.g. hydrophilicity and flexibility.In one embodiment, said linker is flexible. A flexible linker may comprise amino acid residues having small side chains. A non-limiting example of a flexible peptide linker is a glycine rich linker. In one embodiment, said linker is hydrophilic. Thus, a hydrophilic linker typically comprises hydrophilic amino acid residues. In one embodiment, said linker comprises a peptide comprising at least one proline residue, such as two proline residues. Such a proline residue(s) is/are preferably located near the C- and/or N-terminal ends of the linker sequence.The term “antibody” is used herein in its broadest sense, including both monoclonal and polyclonal antibodies, and full-length antibodies such as full length IgG and other antibody isotypes and subtypes. A full-length antibody should be understood as an antibody comprising an antigen-binding variable region as well as a light chain constant domain (CL) and heavy chain constant domains, CH1, CH2 and CH3. Included in the term “antibody” is also antibody fragments such as Fab, Fab′, F(ab′)2and Fv fragments. Single chain fragments thereof such as scFv, Fv, sFab, VHHor a VNAR are also encompassed by the term as used herein. Thus, in one embodiment the target binding antibody is selected from an antibody and a fragment thereof as mentioned above. Antibodies as referred to herein are preferably humanized antibodies.In one embodiment, each of said carrier moieties comprises an antibody or an antibody fragment. Said antibody fragment may be selected from a scFv, Fv, scFab, or a VHH; transferrin or a mutant or variant thereof, or a variant of protein Z derived from domain B of staphylococcal protein A. Said antibody or an antibody fragment is preferably humanized.In one embodiment, each of said carrier moieties comprises a scFv. By using single chain fragments of an antibody, manufacturing of the brain delivery protein may for example be simplified.It should be understood that several different proteins expressed on BBB endothelial cells could be exploited as transportation pathways into the brain for a target binding antibody. Such transportation pathways may utilize receptor-mediated transcytosis for delivery of e.g. antibodies across the BBB. Thus, in one embodiment, said protein expressed on a BBB endothelial cell is selected from transferrin receptor (TfR), insulin receptor (InsR), insulin-like growth factor receptor, low density lipoprotein receptor-related protein 8 (Lrp8), low density lipoprotein receptor-related protein 1 (Lrp1), CD98, transmembrane protein 50A (TMEM50A), glucose transporter 1 (Glut1), basigin (BSG) and heparin-binding epidermal growth factor-like growth factor. Preferably, said protein expressed on a BBB endothelial cell is selected from TfR, InsR, Lrp1, CD98, Glut1 and BSG. In one embodiment, said protein expressed on a BBB endothelial cell is TfR. In one embodiment, said protein expressed on a BBB endothelial cell is InsR. In one embodiment, said protein expressed on a BBB endothelial cell is Lrp1. In one embodiment, said protein expressed on a BBB endothelial cell is CD98. In one embodiment, said protein expressed on a BBB endothelial cell is Glut1. In one embodiment, said protein expressed on a BBB endothelial cell is BSG.It should thus be understood that said two carrier moieties each are capable of monovalent interaction with a protein expressed on a BBB endothelial cell, as exemplified above. In particular, each of said carrier moieties may be an antibody or a protein capable of interacting with for example TfR, InsR, Lrp1, CD98, Glut1 or BSG. In one embodiment, each of said carrier moieties is an antibody fragment directed to TfR. An example of an anti-TfR binding antibody is 8D3. A single chain fragment of the variable domain (scFv8D3) has, as demonstrated in the appended examples, proven advantageous in an example of a brain delivery protein according to the invention.In one embodiment, each of said carrier moieties is an anti-TfR antibody which has low-to-moderate affinity for TfR. An anti-TfR carrier antibody having low-to-moderate affinity for TfR may, compared to a high affinity counterpart, improve brain uptake and distribution of the brain delivery protein, since the TfR system first of all seemingly is saturated at therapeutic doses. Whereas a high affinity variant of an anti-TfR antibody at therapeutic dosing may saturate the TfR system, a low or moderate affinity anti-TfR variant antibody may at the same dosing avoid such TfR saturation. In addition, a low or moderate affinity variant may, compared to a high affinity variant, be released more quickly after encapsulation in the endosome. The high affinity variant may not be released at all which may thus result in degradation of the protein. Moreover, antibodies with less affinity for TfR may remain in circulation at higher concentration than their high affinity counterparts, since they are not cleared from the system as efficiently as those with higher affinity for the TfR. A low or moderate affinity variant of an anti-TfR carrier antibody for instance has a binding affinity for the TfR in the range of 1-10 μM.In one embodiment, said target binding antibody is a full-length antibody, a Fab, F(ab′)2or a Fv. In one embodiment, said target binding antibody is a full length antibody.A brain delivery protein comprising two carrier moieties as disclosed above may moreover prove advantageous from a manufacturing perspective, since the generation of an antibody based brain delivery protein comprising two identical light chains is likely to be produced in higher yields compared with the production of an antibody with two different light chains (i.e. one with and one without a linked carrier antibody).A brain delivery protein according to the present invention may thus comprise a target binding antibody which has binding affinity for any target of interest in the mammalian, such as a human or animal, brain. The brain target may in particular be a target of interest for research purposes, therapy or diagnostics, such as a target involved in a brain disorder, in particular a neurodegenerative disorder. In one embodiment, said target in the brain is selected from amyloid β (Aβ) peptide, alpha synuclein, superoxide dismutase (SOD), huntingtin, transthyretine, P-secretase 1, epidermal growth factor, epidermal growth factor receptor 2, Tau, phosphorylated Tau, apolipoprotein E4, CD20, prion protein, leucine rich repeat kinase 2, parkin, presenilin 2, gamma secretase, death receptor 6, amyloid precursor protein, p75 neurotrophin receptor, neuregulin and caspase 6.Alzheimer's disease (AD) is one of the most common neurodegenerative disorders. Numerous trials have been conducted with antibodies targeting the self-aggregating protein amyloid-β (Aβ). Although amyloid plaques, consisting of fibrillar deposits of Aβ, are a hallmark of AD, soluble Aβ, in particular oligomers and protofibrils, measured in post mortem AD brain tissue and CSF, have been shown to correlate better with disease progression and to be harmful to synapses and neurons. Soluble Aβ assemblies are therefore a suitable target for immunotherapy with Aβ specific antibodies. Thus, in one embodiment, said brain target is an Aβ peptide. In a particular embodiment, said Aβ peptide is soluble Aβ aggregate, preferably selected from oligomers and protofibrils. Examples of anti-Aβ antibodies that bind protofibrils, as well as methods for production thereof, are disclosed in WO 2002/03911, WO 2005/123775, WO 2007/108756, WO 2011/001366, and WO 2016/005466, the disclosures of which are hereby incorporated by reference. A well-studied mouse monoclonal antibody, referred to as mAb158, and its humanized form, referred to as BAN2401, which binds to Aβ protofibrils is disclosed e.g. in WO 2007/108756. In addition, it has no affinity for the Aβ protein precursor. Mutated variants of BAN2401 are disclosed in WO 2016/005466. RmAb158, used as a target binding antibody in the appended examples, is a recombinant version of mAb158 with identical Aβ binding properties.There are other disorders associated with Aβ protein aggregation, such as traumatic brain injury (TBI), Lewy body dementia (LBD), Down syndrome (DS), Amyotrophic lateral sclerosis (ALS), Frontotemporal dementia, tauopathies, systemic amyloidosis, atherosclerosis and Parkinson's disease dementia (PDD). A brain delivery protein comprising a target binding antibody having affinity for an Aβ peptide may prove useful in e.g. therapy or diagnosis of such disorders.In one embodiment, said brain delivery protein comprises an Aβ binding antibody, and two carrier moieties. The Aβ binding antibody may be an antibody having binding specificity for Aβ protofibrils, such as mAb158/BAN2401 or a mutant or variant thereof as disclosed in any one of the prior art publications specifically mentioned above. In particular embodiments, such a brain delivery protein comprises two carrier antibodies, each being linked to a C-terminal end of a (separate) light chain of the Aβ binding antibody by a linker. Each of the carrier moieties may for example be an anti-TfR antibody or a fragment thereof as defined herein, such as a scFv8D3, optionally linked by a linker as set out in SEQ ID NO:1 to the target binding moiety.In one embodiment, said Aβ binding antibody is mAb158/BAN2401 or a mutant or variant thereof and each of said carrier moieties is a scFv8D3, wherein each of said scFv8D3 is linked to a C-terminal end of a light chain of said mAb158/BAN2401 or mutant or variant thereof, said protein optionally further comprising two linkers, each linker having an amino acid sequence as set out in SEQ ID NO:1, for linking said scFv8D3 to said said mAb158/BAN2401 or mutant or variant thereof.In one embodiment, said brain target is alpha synuclein. Parkinson's disease (PD) and Lewy body dementia (LBD) are the two most prevalent examples of neurodegenerative disorders with alpha synuclein brain pathology. Other examples include the Lewy body variant of Alzheimer's disease, multiple system atrophy, psychosis, schizophrenia, and Creutzfeldt-Jakob disease. In one embodiment, said alpha synuclein is soluble alpha synuclein, preferably selected from oligomers and protofibrils. A target binding antibody which binds alpha synuclein may in particular have high affinity for human alpha synuclein protofibrils and low binding of alpha synuclein monomers. Specific examples of anti-alpha synuclein antibodies are disclosed in WO 2009/133521, WO 2011/104696, which are hereby incorporated by reference.In one embodiment, said brain delivery protein comprises an alpha synuclein binding antibody, and two carrier moieties. In one embodiment, said alpha synuclein binding antibody binds human alpha synuclein protofibrils, preferably said alpha synuclein binding antibody does not bind alpha synuclein monomers. The alpha synuclein binding antibody may be an antibody or an antibody variant as disclosed in any one of the prior art references mentioned above. One example of a alpha synuclein binding antibody is mAb48, or a mutant or variant thereof. mAb48 is disclosed in WO 2011/104696 and denoted “48611/8” and described inter alia on pages 31-32 in Tables 1 and 2. In particular embodiments, such a brain delivery protein comprises two carrier antibodies, each being linked to a C-terminal end of a light chain of the alpha synuclein binding antibody by a linker. Each of the two carrier moieties may for example be an anti-TfR antibody, such as a scFv8D3, optionally linked by a linker as set out in SEQ ID NO:1 to the target binding moiety.In one embodiment, said alpha synuclein binding antibody is mAb48 or a mutant or variant thereof and each of said carrier moieties is a scFv8D3, wherein each of said scFv8D3 is linked to a C-terminal end of a light chain of said mAb48 or mutant or variant thereof, said protein optionally further comprising two linkers, each linker having an amino acid sequence as set out in SEQ ID NO:1, for linking said scFv8D3 to said said mAb48 or mutant or variant thereof.In one embodiment, said brain target is SOD. A brain delivery protein comprising a SOD directed antibody may be useful in e.g. treatment and diagnosis of ALS.In one embodiment, said brain target is huntingtin. A brain delivery protein comprising an antibody directed to huntingtin may be useful in e.g. treatment and diagnosis of Huntington's disease.In one embodiment, said brain target is transthyretin. A brain delivery protein comprising an antibody directed to transthyretin may be useful in e.g. treatment and diagnosis of familial amyloid neuropathy.In one embodiment, said target binding antibody is a humanized antibody.In one embodiment, said brain delivery protein is recombinant.In one embodiment, said protein is a fusion protein. In particular, said protein may be expressed as a fusion protein.In a related aspect there is provided an isolated nucleic acid encoding the protein according to any one of the preceding claims. An expression vector comprising such a nucleic acid may enable production of a brain delivery protein for example by expression in a host cell.The brain delivery protein according to the invention may be useful as a therapeutic or diagnostic agent or as a research tool, e.g. as a PET or SPECT ligand. In one embodiment, said brain delivery protein is for use in prophylaxis or therapy. For example, said brain delivery protein is for use in treatment and/or prophylaxis of a brain disorder such as a neurodegenerative disorder.In one embodiment, said brain delivery protein is for use in treatment and/or prophylaxis of a neurodegenerative disorder selected from the group consisting of Alzheimer's disease and other disorders associated with Aβ protein aggregation, such as traumatic brain injury (TBI), Lewy body dementia (LBD), Downs syndrome (DS), Amyotrophic lateral sclerosis (ALS), Frontotemporal dementia, tauopathies, systemic amyloidoses, atherosclerosis and Parkinson's disease dementia (PDD); the Lewy body variant of Alzheimer's disease; multiple system atrophy; psychosis; schizophrenia; Creutzfeldt-Jakob disease; Huntington's disease, and Familial amyloid neuropathy.In one embodiment, said brain delivery protein is for use in treatment and/or prophylaxis of Alzheimer's disease. In particular, such a brain delivery protein comprises a target binding protein which binds to Aβ peptide, preferably a soluble form of an Aβ peptide such as oligomers and/or protofibrils.In one embodiment, said brain delivery protein is for use in treatment and/or prophylaxis of Parkinsons's disease. In particular, such a brain delivery protein comprises a target binding protein which binds alpha synuclein, preferably a soluble form of alpha synuclein, such as oligomers and/or protofibrils.In one embodiment, said brain delivery protein is for use in in vivo diagnostics. For example, said brain delivery protein is for use in in vivo diagnostics of a brain disorder such as a neurodegenerative disorder.In one embodiment, said brain delivery protein is for use in in vivo diagnostics of a neurodegenerative disorder selected from the group consisting of Alzheimer's disease and other disorders associated with Aβ protein aggregation, such as traumatic brain injury (TBI), Lewy body dementia (LBD), Downs syndrome (DS), Amyotrophic lateral sclerosis (ALS), Frontotemporal dementia, tauopathies, systemic amyloidoses, atherosclerosis and Parkinson's disease dementia (PDD); the Lewy body variant of Alzheimer's disease; multiple system atrophy; psychosis; schizophrenia; Creutzfeldt-Jakob disease; Huntington's disease, and familial amyloid neuropathy.In one embodiment, said brain delivery protein is for use in in vivo diagnostics of Alzheimer's disease. In particular, such a brain delivery protein comprises a target binding protein which binds to Aβ peptide, preferably a soluble form of an Aβ peptide such as oligomers and/or protofibrils.In one embodiment, said brain delivery protein is for use in treatment of Parkinsons's disease. In particular, such a brain delivery protein comprises a target binding protein which binds alpha synuclein, preferably a soluble form of alpha synuclein, such as oligomers and/or protofibrils.In one embodiment, said brain delivery protein is for use in in vivo diagnostics using PET.In one embodiment, said brain delivery protein further comprises a label enabling detection of said protein in the brain. In this context a label should be understood as a marker which is coupled to the brain delivery protein and which is intended for use in detection and/or imaging for inter alia medical, diagnostic or research purposes. The label may be coupled either to the target binding antibody or to one of the carrier moieties. Non-limiting examples of such labels include radiolabel, a fluorophore, a chromophore, or an affinity tag. In one embodiment, the label is a radiolabel used for medical or diagnostic imaging, for example Zr89, I124, I125, I131, C11, C14, H3, F18, or Gallium68, suitable for use in SPECT (Single-photon emission computed tomography) or PET (Positron Emission Tomography) imaging.The brain delivery protein as disclosed herein is suitably directed to a target in the mammalian brain. Thus, the brain delivery protein of the present invention is suitable for therapeutic or diagnostic use in a mammal. A mammal as used herein includes, but is not limited to, domesticated animals (e.g. cows, sheep, cats, dogs, and horses), primates (e.g. humans and non-human primates such as monkeys), rabbits, and rodents (e.g. mice and rats). In certain embodiments, the mammal is a human.In a related aspect, there is provided a pharmaceutical composition comprising a brain delivery protein according to the present invention and a pharmaceutically acceptable carrier. In a specific embodiment for therapeutic use, the compositions are physiologically acceptable formulations comprising a therapeutically active amount of a brain delivery protein according to the invention in a physiological buffer suitable for administration to humans and/or animals. The brain delivery protein can be freeze dried for better stability. The freeze dried formulation may contain any suitable conventional excipients, including stabilizers, lyoprotectants, buffers, and the like, such as, but not limited to, mannitol, for protecting and/or stabilizing the product during and/or after freeze drying and/or subsequent storage.In a related aspect, there is provided a method for treatment and/or prophylaxis of a brain disorder in a mammal having, or being at risk of developing said disorder, comprising administering to said mammal a therapeutically effective amount of the brain delivery protein according to the invention. In particular, said disorder is a neurodegenerative disorder selected from the group consisting of Alzheimer's disease and other disorders associated with Aβ protein aggregation, such as traumatic brain injury (TBI), Lewy body dementia (LBD), Downs syndrome (DS), Amyotrophic lateral sclerosis (ALS), Frontotemporal dementia, tauopathies, systemic amyloidoses, atherosclerosis and Parkinson's disease dementia (PDD); the Lewy body variant of Alzheimer's disease; multiple system atrophy; psychosis; schizophrenia; Creutzfeldt-Jakob disease; Huntington's disease, and familial amyloid neuropathy. As disclosed above, particular target binding antibodies may be useful in treatment of certain neurodegenerative disorders due to their binding affinity for certain brain targets. The embodiments as disclosed for related aspects of the present invention are thus equally relevant also for the method of treatment aspect of the invention.In a related aspect, there is provided a method for diagnosing and/or detecting a brain disorder in a mammal suspected of having, or being at risk of developing said disorder, comprising administering to said mammal the brain delivery protein according to the invention in an amount sufficient to enable diagnosis and/or detection. In a particular embodiment, said disorder is a neurodegenerative disorder such as a neurodegenerative disorder selected from the group consisting of Alzheimer's disease and other disorders associated with Aβ protein aggregation, such as traumatic brain injury (TBI), Lewy body dementia (LBD), Downs syndrome (DS), Amyotrophic lateral sclerosis (ALS), Frontotemporal dementia, tauopathies, systemic amyloidoses, atherosclerosis and Parkinson's disease dementia (PDD); the Lewy body variant of Alzheimer's disease; multiple system atrophy; psychosis; schizophrenia; Creutzfeldt-Jakob disease; Huntington's disease, and familial amyloid neuropathy. As disclosed above, particular target binding antibodies may be useful in diagnosis or detection of certain disorders due to their binding affinity for certain brain targets. It should be understood that specific embodiments of the method for diagnosing and/or detecting may be in vivo or in vitro methods, such as in vivo diagnostics in the brain of a mammal or such as in vitro diagnostics of a cell sample. The embodiments as disclosed for related aspects of the present invention are thus equally relevant also for the aspect of diagnosing/detecting as disclosed above.The invention will be further illustrated by the following non-limiting examples.

