Patent Publication Number: US-2022235139-A1

Title: Anti-csf-ir antibody

Description:
FIELD OF THE INVENTION 
     The present invention relates to a monoclonal antibody, or fragment thereof, which binds to CSF-1R (Colony stimulating factor 1 receptor), in particular to human CSF-1R. The present invention further relates to the in vitro use of the monoclonal antibody, or fragment thereof, of the present invention for the detection of CSF-1R in a sample. Further encompassed by the present invention is a complex comprising the monoclonal antibody, or fragment thereof, of the present invention and CSF-1R such as the human CSF-1R polypeptide. 
     BACKGROUND OF THE INVENTION 
     The human CSF-1 receptor (CSF-1R; colony stimulating factor 1 receptor) is a growth factor and encoded by the c-fms proto-oncogene (reviewed e.g. in Roth, P., and Stanley, E. R., Curr. Top. Microbiol. Immunol. 181 (1992) 141-167). 
     Currently two CSF-1R ligands that bind to the extracellular domain of CSF-1R are known. The first one is CSF-1 (colony stimulating factor 1) and is found extracellularly as a disulfide-linked homodimer (Stanley et al., Stem Cells 12 Suppl. 1 (1995) 15-24). The second one is IL-34 (Hume et al., Blood 119 (2012) 1810-1820). The main biological effects of CSF-1R signaling are the differentiation, proliferation, migration, and survival of hematopoietic precursor cells to the macrophage lineage. Activation of CSF-1R is mediated by its CSF-1R ligands, CSF-1 and IL-34. Binding of CSF-1 to CSF-1R induces the formation of homodimers and activation of the kinase by tyrosine phosphorylation (Stanley et al., Mol. Reprod. Dev. 46 (1997) 4-10). 
     CSF-1R has been associated with many diseases and disorders (see e.g. Cannarile, M. A., et al. (2017), J Immunother Cancer 5(1): 53, Ries, C. H., et al. (2014), Cancer Cell 25(6): 846-859). For example, CSF-1R plays an important role in initiating inflammatory, cancer, and bone disorders. Therefore, many CSF-1R inhibitors (such as small molecule inhibitors and monoclonal antibodies) have been described and are analyzed in clinical trials (reviewed by El-Gamal et al., J Med Chem. 2018, 61(13):5450-5466). 
     Anti-CSF-1R antibodies are e.g. disclosed in WO2011/123381, WO2011/140249 and WO2012/110360. 
     The extracellular domain of the CSF-1 receptor (CSF-1R-ECD) comprises five subdomains (D1 to D5). The biologically active homodimer CSF-1 binds to the CSF-1R within the subdomains D1 to D3. The subdomains D4 to D5 of the extracellular domain are not involved in the CSF-1 binding (Wang et al., Molecular and Cellular Biology 13 (1993) 5348-5359). The subdomain D4 is involved in dimerization (Pixley et al., Trends Cell Biol. 14 (2004) 628-638). 
     Many therapeutic candidate anti-CSF-1R antibodies bind to the extracellular domain of the CSF-1 receptor (CSF-1R-ECD). E.g. WO 2009/026303 and WO 2009/112245 disclose anti-CSF-1R antibodies binding to CSF-1R within the first three subdomains (D1 to D3) of the extracellular domain. WO2011/070024 discloses anti-CSF-1R antibodies binding to CSF-1R within the dimerization domain (D4 to D5). 
     In addition to antibodies which bind to the extracellular domain of the CSF-1 receptor, antibodies which bind to other domains have been described such as antibodies which bind the CSF-1R kinase domain. For example, polyclonal antibodies which bind to phosphorylation sites of CSF-1R are commercially available from Thermo Fisher such as Phospho-CSF1R (Tyr561), Phospho-CSF1R (Tyr699), Phospho-CSF1R (Tyr708), Phospho-CSF1R (Tyr723), Phospho-CSF1R (Tyr809), Phospho-CSF1R (Tyr921). The polyclonal antibodies were generated by using chemically synthesized phosphopeptides as immunogen. 
     Further, a monoclonal antibody has been produced by immunizing rabbits with a synthetic phosphopeptide corresponding to residues surrounding Tyr708 of human CSF-1R receptor protein. The antibody, termed “Phospho-M-CSF Receptor (Tyr708) (D5F4Y) Rabbit mAb #14591” is commercially available from Bioke (Leiden, The Netherlands). The antibody recognizes endogenous levels of CSF-1R only when phosphorylated at Tyr708, but may cross-react with other activated protein tyrosine kinases such as phospho-Src. Accordingly, the antibody might not be suitable for immunohistochemistry (IHC). 
     WO2012/150320 describes a scaffold technology for the production of antibodies. The document describes a fusion polypeptide comprising one or more fragments of a peptidyl-prolyl cis/trans isomerase or FKBP domain family members and its use in methods for antibody screening/selection, for epitope mapping as well as its use as immunogen for the production of antibodies specifically binding an immunogenic peptide or secondary structure presented by the fusion polypeptide. WO2015/044083 discloses that the  Thermus thermophilus  SlyD FKBP domain is suited in the fusion polypeptide for generating antibodies. 
     The inventors have grafted a fragment of the kinase domain of human CSF-1R onto the  Thermus thermophilus  SlyD FKBP scaffold. The generated fusion polypeptide was used as immunogen for the generation of monoclonal antibodies in rabbits. It was shown that the antibodies showed high antibody/receptor affinity and specificity versus CSF-1R, in particular the antibody termed “1H11”. The antibody showed excellent immunohistochemistry performance and could be therefore applied in clinical studies with small molecules or antibodies targeting CSF-1R. Surprisingly, the antibody was capable of detecting both native and denatured CSF-1R. 
     BRIEF SUMMARY OF THE PRESENT INVENTION 
     The present invention relates to a monoclonal antibody, or fragment thereof, which binds to CSF-1R (Colony stimulating factor 1 receptor), in particular to human CSF-1R. 
     In an embodiment of the present invention, the monoclonal antibody, or fragment thereof, comprises a light chain variable domain that is at least 85% identical to the light chain variable domain having a sequence as shown in SEQ ID NO: 2, and/or wherein said monoclonal antibody, or fragment thereof, comprises a heavy chain variable domain that is at least 85% identical to the heavy chain variable domain having a sequence as shown in SEQ ID NO: 3. 
     In an embodiment of the present invention, the monoclonal antibody, or fragment thereof, comprises
         (a) a light chain variable domain comprising
           (a1) a light chain CDR1 that differs by not more than a total of three amino acid additions, substitutions, and/or deletions from a light chain CDR1 having an amino acid sequence as shown in SEQ ID NO: 4 (QSSESVYSNNFLS),   (a2) a light chain CDR2 that differs by not more than a total of three amino acid additions, substitutions, and/or deletions from a light chain CDR2 having an amino acid sequence as shown in SEQ ID NO: 5 (EASKVAS), and/or   (a3) a light chain CDR3 that differs by not more than a total of three amino acid additions, substitutions, and/or deletions from a light chain CDR3 having an amino acid sequence as shown in SEQ ID NO: 6 (AGGYDVSDDA),   
           (b) a heavy chain variable domain comprising
           (b1) a heavy chain CDR1 that differs by not more than a total of three amino acid additions, substitutions, and/or deletions from a heavy chain CDR1 having an amino acid sequence as shown in SEQ ID NO: 7 (TASGFSLSRYWMT),   (b2) a heavy chain CDR2 that differs by not more than a total of three amino acid additions, substitutions, and/or deletions from a heavy chain CDR2 having an amino acid sequence as shown in SEQ ID NO: 8 (RSGNTYFADWAKG), and/or   (b3) a heavy chain CDR3 that differs by not more than a total of three amino acid additions, substitutions, and/or deletions from a heavy chain CDR3 having an amino acid sequence as shown in SEQ ID NO: 9 (GGQNNGYDL), or   
           (c) both the light chain variable domain as defined under (a) and the heavy chain variable domain as defined under (b).       

     In an embodiment of the monoclonal antibody of the present invention, or the fragment thereof, the epitope of the monoclonal antibody, or fragment thereof, comprises a sequence as shown in SEQ ID NO: 1 (YKNIHLEKKY). Preferably, at least one of the two Tyrosine residues, in particular both Tyrosine residues, of said epitope is phosphorylated. 
     In an embodiment, the monoclonal antibody, or fragment thereof, comprises
         (a) a light chain variable domain comprising
           (a1) a light chain CDR1 having a sequence as shown in SEQ ID NO: 4 (QSSESVYSNNFLS),   (a2) a light chain CDR2 having a sequence as shown in SEQ ID NO: 5 (EASKVAS), and   (a3) a light chain CDR3 having a sequence as shown in SEQ ID NO: 6 (AGGYDVSDDA), and   
           (b) a heavy chain variable domain comprising
           (b1) a heavy chain CDR1 having a sequence as shown in SEQ ID NO: 7 (TASGFSLSRYWMT),   (b2) a heavy chain CDR2 having a sequence as shown in SEQ ID NO: 8 (RSGNTYFADWAKG), and   (b3) a heavy chain CDR3 having a sequence as shown in SEQ ID NO: 9 (GGQNNGYDL).   
               

     The present invention further relates to the in vitro use of the monoclonal antibody, or fragment thereof, of any one the present invention for the detection of CSF-1R in a sample. 
     The present invention further contemplates a method for detecting CSF-1R in a sample, comprising
         (a) contacting a sample comprising CSF-1R with the monoclonal antibody, or fragment thereof, of the present invention, thereby forming a complex comprising CSF-1R and said monoclonal antibody, or fragment thereof, and   (b) detecting the complex formed in step (a), thereby detecting CSF-1R in said sample.       

     The present invention further contemplates a complex comprising the monoclonal antibody, or fragment thereof, of the present invention and CSF-1R such as the human CSF-1R polypeptide. 
     DETAILED DESCRIPTION OF THE INVENTION 
     As set forth above, the present invention relates to a monoclonal antibody, or fragment thereof, which binds to CSF-1R (Colony stimulating factor 1 receptor), in particular to human CSF-1R. 
     CSF-1R is a polypeptide belonging to the class III subfamily of receptor tyrosine kinases and is encoded by the c-fms proto-oncogene. Synonyms of CSF-1R are M-CSF receptor; Macrophage colony-stimulating factor 1 receptor, Fms proto-oncogene and c-fms. Binding of CSF-1 or IL-34 induces receptor dimerization, followed by autophosphorylation and activation of downstream signaling cascades. Activation of CSF-IR regulates the survival, proliferation and differentiation of monocytes and macrophages (Xiong, Y. et al., J. Biol. Chem. 286 (2011) 952-960). Preferably, the monoclonal antibody (or antigen-binding fragment thereof) of the present invention binds to the human CSF-1R polypeptide. Human CSF-IR is known since 1986 (Coussens, L., et al, Nature 320 (1986) 277-280). The cloning of the receptor was described for the first time in Roussel, M. F., et al., Nature 325 (1987) 549-552. CSF-1R is a single chain, transmembrane receptor tyrosine kinase (RTK) and a member of the family of immunoglobulin (Ig) motif containing RTKs characterized by 5 repeated Ig-like subdomains D1-D5 in the extracellular domain (ECD) of the receptor (Wang, Z., et al Molecular and Cellular Biology 13 (1993) 5348-5359). The intracellular domain of CSF-1R comprises, inter alia, the kinase domain of CSF-1R. 
     
       
         
           
               
            
               
                 The amino acid sequence of full length human CSF- 
               
               
                 1R is as follows (SEQ ID NO: 10): 
               
               
                 MGPGVLLLLLVATAWHGQG IPVIEPSVPELVVKPGATVTLRCVGNGSVEW   
               
               
                   
               
               
                 
                   DGPPSPHWTLYSDGSSSILSTNNATFQNTGTYRCTEPGDPLGGSAAIHLY 
                 
               
               
                   
               
               
                 
                   VKDPARPWNVLAQEVVVFEDQDALLPCLLTDPVLEAGVSLVRVRGRPLMR 
                 
               
               
                   
               
               
                 
                   HTNYSFSPWHGFTIHRAKFIQSQDYQCSALMGGRKVMSISIRLKVQKVIP 
                 
               
               
                   
               
               
                 
                   GPPALTLVPAELVRIRGEAAQIVCSASSVDVNFDVFLQHNNTKLAIPQQS 
                 
               
               
                   
               
               
                 
                   DFHNNRYQKVLTLNLDQVDFQHAGNYSCVASNVQGKHSTSMFFRVVESAY 
                 
               
               
                   
               
               
                 
                   LNLSSEQNLIQEVTVGEGLNLKVMVEAYPGLQGFNWTYLGPFSDHQPEPK 
                 
               
               
                   
               
               
                 
                   LANATTKDTYRHTFTLSLPRLKPSEAGRYSFLARNPGGWRALTFELTLRY 
                 
               
               
                   
               
               
                 
                   PPEVSVIWTFINGSGTLLCAASGYPQPNVTWLQCSGHTDRCDEAQVLQVW 
                 
               
               
                   
               
               
                 
                   DDPYPEVLSQEPFHKVIVQSLLTVETLEHNQTYECRAHNSVGSGSWAFIP 
                 
               
               
                   
               
               
                   ISAGAHTHPPDEFLFTP VVVACMSIMALLLLLLLLLLY KYKQKPKYQVRW   
               
               
                   
               
               
                 
                   KIIESYEGNSYTFIDPTQLPYNEKWEFPRNNLQFGKTLGAGAFGKVVEAT 
                 
               
               
                   
               
               
                 
                   AFGLGKEDAVLKVAVKMLKSTAHADEKEALMSELKIMSHLGQHENIVNL 
                 
               
               
                   
               
               
                 
                   LGACTHGGPVLVITEYCCYGDLLNFLRRKAEAMLGPSLSPGQDPEGGVD 
                 
               
               
                   
               
               
                 
                   
                   
                   VRRDSGFSSQGVDTYVEMRPVSTSSNDSFSEQDLDKEDGR 
                 
               
               
                   
               
               
                 
                   PLELRDLLHFSSQVAQGMAFLASKNCIHRDVAARNVLLTNGHVAKIGDF 
                 
               
               
                   
               
               
                 
                   GLARDIMNDSNYIVKGNARLPVKWMAPESIFDCVYTVQSDVWSYGILLWE 
                 
               
               
                   
               
               
                 
                   IFSLGLNPYPGILVNSKFYKLVKDGYQMAQPAFAPKNIYSIMQACWALEP 
                 
               
               
                   
               
               
                 
                   THRPTFQQICSFLQEQAQEDRRERDYTNLPSSSRSGGSGSSSSELEEESS 
                 
               
               
                   
               
               
                 
                   SHLTCCEQGDIAQPLLQPNNYQFC 
                 
               
            
           
         
       
     
     The extracellular domain of human CSF-1R is underlined, the intracellular domain is shown in italics in the above sequence. The first 19 amino acids (signal peptide) are cleaved off after translation to form the mature form of the CSF-1R polypeptide. The epitope region of the antibody identified in studies underlying the present invention is shown in bold. The sequence of the epitope is also shown in SEQ ID NO: 1 (YKNIHLEKKY). As described herein below in more detail, the Tyrosine residue at position 699 and/or the Tyrosine residue at position 708 is/are phosphorylated. 
     Advantageously, the antibody of the present invention binds to both the native form, i.e. the undenatured form, of CSF-1R and the denatured form of CSF-1R. Thus, the term “CSF-1R” includes native CSF-1R and denatured CSF-1. 
     The antibody, or antigen-binding fragment of the present invention shall have the following sequence: 
     Preferably, the monoclonal antibody, or fragment thereof, which binds to CSF-1R (Colony stimulating factor 1 receptor) comprises a light chain variable domain that is, in increasing order of preference at least 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99% identical to the light chain variable domain having a sequence as shown in SEQ ID NO: 2, and/or a heavy chain variable domain that is at least 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99% identical to the heavy chain variable domain having a sequence as shown in SEQ ID NO: 3. In particular, the monoclonal antibody, or fragment thereof, comprises a light chain variable domain that is, in increasing order of preference at least 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99% identical to the light chain variable domain having a sequence as shown in SEQ ID NO: 2, and a heavy chain variable domain that is at least 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99% identical to the heavy chain variable domain having a sequence as shown in SEQ ID NO: 3. For example, the monoclonal antibody, or fragment thereof, comprises a light chain variable domain that is, in increasing order of preference at least 85% identical to the light chain variable domain having a sequence as shown in SEQ ID NO: 2, and a heavy chain variable domain that is at least 85% identical to the heavy chain variable domain having a sequence as shown in SEQ ID NO: 3. 
     In an aspect, the monoclonal antibody comprises a light chain variable domain having a sequence as shown in SEQ ID NO: 2, and a heavy chain variable domain having a sequence as shown in SEQ ID NO: 3. 
     
       
         
           
               
            
               
                 The sequence of the light chain variable region is 
               
               
                 a follows (SEQ ID NO: 2): 
               
               
                 AAVLTQTPSPVSAAVGGTVTISCQSSESVYSNNFLSWYQLKPGQRPRLLI 
               
               
                   
               
               
                 YEASKVASGVPSRFSGSGSGTQFTLTISGVQCDDAATYYCAGGYDVSDDA 
               
               
                   
               
               
                 FGGGTEVLVK 
               
               
                   
               
               
                 The sequence of the heavy chain variable region is 
               
               
                 a follows (SEQ ID NO: 3): 
               
               
                 QSVEESGGRLVTPGTPLTLTCTASGFSLSRYWMTWVRQAPGKGLEYIGWI 
               
               
                   
               
               
                 DRSGNTYFADWAKGRFTGSKTSTTRDLKITSPTTEDTATYFCGRGGQNNG 
               
               
                   
               
               
                 YDLWGPGTLVTVSS 
               
            
           
         
       
     
     Alternatively or additionally, the monoclonal antibody, or fragment thereof, of the present invention comprises
         (a) a light chain variable domain comprising
           (a1) a light chain CDR1 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a light chain CDR1 having an amino acid sequence as shown in SEQ ID NO: 4 (QSSESVYSNNFLS),   (a2) a light chain CDR2 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a light chain CDR2 having an amino acid sequence as shown in SEQ ID NO: 5 (EASKVAS), and/or   (a3) a light chain CDR3 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a light chain CDR3 having an amino acid sequence as shown in SEQ ID NO: 6 (AGGYDVSDDA), and/or   
           (b) a heavy chain variable domain comprising
           (b1) a heavy chain CDR1 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a heavy chain CDR1 having an amino acid sequence as shown in SEQ ID NO: 7 (TASGFSLSRYWMT),   (b2) a heavy chain CDR2 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a heavy chain CDR2 having an amino acid sequence as shown in SEQ ID NO: 8 (RSGNTYFADWAKG), and/or   (b3) a heavy chain CDR3 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a heavy chain CDR3 having an amino acid sequence as shown in SEQ ID NO: 9 (GGQNNGYDL),   or   both the light chain variable domain as defined under (a) and the heavy chain variable domain as defined under (b).   
               

     Alternatively or additionally, the monoclonal antibody, or fragment thereof, of the present invention comprises
         (a) a light chain variable domain comprising
           (a1) a light chain CDR1 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a light chain CDR1 having an amino acid sequence as shown in SEQ ID NO: 4 (QSSESVYSNNFLS),   (a2) a light chain CDR2 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a light chain CDR2 having an amino acid sequence as shown in SEQ ID NO: 5 (EASKVAS), and   (a3) a light chain CDR3 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a light chain CDR3 having an amino acid sequence as shown in SEQ ID NO: 6 (AGGYDVSDDA),   and   
           (b) a heavy chain variable domain comprising
           (b1) a heavy chain CDR1 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a heavy chain CDR1 having an amino acid sequence as shown in SEQ ID NO: 7 (TASGFSLSRYWMT),   (b2) a heavy chain CDR2 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a heavy chain CDR2 having an amino acid sequence as shown in SEQ ID NO: 8 (RSGNTYFADWAKG), and   (b3) a heavy chain CDR3 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a heavy chain CDR3 having an amino acid sequence as shown in SEQ ID NO: 9 (GGQNNGYDL).   
               

     In an aspect, the monoclonal antibody, or fragment thereof, of the present invention comprises
         (a) a light chain variable domain comprising
           (a1) a light chain CDR1 comprising at least 11, in particular at least 12 consecutive amino acids of the amino acid sequence as shown in SEQ ID NO: 4 (QSSESVYSNNFLS),   (a2) a light chain CDR2 comprising at least 5, in particular at least 6 consecutive amino acids of the amino acid sequence as shown in SEQ ID NO: 5 (EASKVAS), and/or   (a3) a light chain CDR3 comprising at least 8, in particular at least 9 consecutive amino acids of the amino acid sequence as shown in SEQ ID NO: 6 (AGGYDVSDDA),   and/or   
           (b) a heavy chain variable domain comprising
           (b1) a heavy chain CDR1 comprising at least 11, in particular at least 12 consecutive amino acids of the amino acid sequence as shown in SEQ ID NO: 7 (TASGFSLSRYWMT),   (b2) a heavy chain CDR2 comprising at least 11, in particular at least 12 consecutive amino acids of the amino acid sequence as shown in SEQ ID NO: 8 (RSGNTYFADWAKG), and/or   (b3) a heavy chain CDR3 comprising at least 7, in particular at least 8 consecutive amino acids of the amino acid sequence as shown in SEQ ID NO: 9 (GGQNNGYDL).   
               

     In an aspect, the monoclonal antibody, or fragment thereof, of the present invention comprises
         (a) a light chain variable domain comprising
           (a1) a light chain CDR1 having a sequence as shown in SEQ ID NO: 4 (QSSESVYSNNFLS),   (a2) a light chain CDR2 having a sequence as shown in SEQ ID NO: 5 (EASKVAS), and/or   (a3) a light chain CDR3 having a sequence as shown in SEQ ID NO: 6 (AGGYDVSDDA),   and/or   
           (b) a heavy chain variable domain comprising
           (b1) a heavy chain CDR1 having a sequence as shown in SEQ ID NO: 7 (TASGFSLSRYWMT),   (b2) a heavy chain CDR2 having a sequence as shown in SEQ ID NO: 8 (RSGNTYFADWAKG), and/or   (b3) a heavy chain CDR3 having a sequence as shown in SEQ ID NO: 9 (GGQNNGYDL).   
               

     In an aspect, the monoclonal antibody, or fragment thereof, of the present invention comprises
         (a) a light chain variable domain comprising
           (a1) a light chain CDR1 having a sequence as shown in SEQ ID NO: 4 (QSSESVYSNNFLS),   (a2) a light chain CDR2 having a sequence as shown in SEQ ID NO: 5 (EASKVAS), and   (a3) a light chain CDR3 having a sequence as shown in SEQ ID NO: 6 (AGGYDVSDDA), and   
           (b) a heavy chain variable domain comprising
           (b1) a heavy chain CDR1 having a sequence as shown in SEQ ID NO: 7 (TASGFSLSRYWMT),   (b2) a heavy chain CDR2 having a sequence as shown in SEQ ID NO: 8 (RSGNTYFADWAKG), and   (b3) a heavy chain CDR3 having a sequence as shown in SEQ ID NO: 9 (GGQNNGYDL).   
               

     Also preferably, the monoclonal antibody, or fragment thereof, which binds to CSF-1R (Colony stimulating factor 1 receptor) comprises a light chain variable domain that is, in increasing order of preference at least 70%, 75%, 80%, 85%, 90%, 95%, 98%, 99% or 100% identical to the light chain variable domain having a sequence as shown in SEQ ID NO: 2, and/or a heavy chain variable domain that is at least 70%, 75%, 80%, 85%, 90%, 95%, 98%, 99% or 100% identical to the heavy chain variable domain having a sequence as shown in SEQ ID NO: 3, 
     wherein the light chain variable domain comprises
         (a1) a light chain CDR1 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a light chain CDR1 having an amino acid sequence as shown in SEQ ID NO: 4 (QSSESVYSNNFLS),   (a2) a light chain CDR2 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a light chain CDR2 having an amino acid sequence as shown in SEQ ID NO: 5 (EASKVAS), and   (a3) a light chain CDR3 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a light chain CDR3 having an amino acid sequence as shown in SEQ ID NO: 6 (AGGYDVSDDA),   and
 
wherein the a heavy chain variable domain comprises
   (b1) a heavy chain CDR1 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a heavy chain CDR1 having an amino acid sequence as shown in SEQ ID NO: 7 (TASGFSLSRYWMT),   (b2) a heavy chain CDR2 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a heavy chain CDR2 having an amino acid sequence as shown in SEQ ID NO: 8 (RSGNTYFADWAKG), and   (b3) a heavy chain CDR3 that differs by not more than a total of three, two, or in particular one amino acid additions, substitutions, and/or deletions from a heavy chain CDR3 having an amino acid sequence as shown in SEQ ID NO: 9 (GGQNNGYDL).       

     “Percent (%) amino acid sequence identity” with respect to a reference polypeptide sequence is defined as the percentage of amino acid residues in a candidate sequence that are identical with the amino acid residues in the reference polypeptide sequence, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity. Preferably, standard parameters are applied for determining the degree of sequence identity of two sequences. Preferably, the degree of identity is to be determined by comparing two optimally aligned sequences over a comparison window, where the fragment of amino acid sequence in the comparison window may comprise additions or deletions (e.g., gaps or overhangs) as compared to the reference sequence (which does not comprise additions or deletions) for optimal alignment. The percentage is calculated by determining the number of positions at which the identical amino acid residue occurs in both sequences to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the window of comparison and multiplying the result by 100 to yield the percentage of sequence identity. Optimal alignment of sequences for comparison may be conducted by the local homology algorithm of Smith and Waterman Add. APL. Math. 2:482 (1981), by the homology alignment algorithm of Needleman and Wunsch J. Mol. Biol. 48:443 (1970), by the search for similarity method of Pearson and Lipman Proc. Natl. Acad. Sci. (USA) 85: 2444 (1988), by computerized implementations of these algorithms (GAP, BESTFIT, BLAST, PASTA, and TFASTA in the Wisconsin Genetics Software Package, Genetics Computer Group (GCG), 575 Science Dr., Madison, Wis.), or by visual inspection. Given that two sequences have been identified for comparison, GAP and BESTFIT are preferably employed to determine their optimal alignment and, thus, the degree of identity. Preferably, the default values of 5.00 for gap weight and 0.30 for gap weight length are used. In an embodiment, the percent identity between two amino acid sequences is determined using the Needleman and Wunsch algorithm (Needleman 1970, J. Mol. Biol. (48):444-453) which has been incorporated into the needle program in the EMBOSS software package (EMBOSS: The European Molecular Biology Open Software Suite, Rice, P., Longden, I., and Bleasby, A., Trends in Genetics 16(6), 276-277, 2000), a BLOSUM62 scoring matrix, and a gap opening penalty of 10 and a gap entension pentalty of 0.5. A preferred, non-limiting example of parameters to be used for aligning two amino acid sequences using the needle program are the default parameters, including the EBLOSUM62 scoring matrix, a gap opening penalty of 10 and a gap extension penalty of 0.5. 
     The term “antibody” refers to immunoglobulins or immunoglobulin-like molecules including by way of example and without limitation, IgA, IgD, IgE, IgG and IgM, combinations thereof, and similar molecules produced during an immune response in any vertebrate, for example, in mammals such as goats, rabbits and mice, as well as non-mammalian species, such as shark immunoglobulins. For example, the antibody may be a rabbit antibody. The term “antibody” includes intact immunoglobulins and “antibody fragments” or “antigen binding fragments” that specifically bind to a molecule of interest (or a group of highly similar molecules of interest) to the substantial exclusion of binding to other molecules. The term “antibody” also includes genetically engineered forms such as chimeric antibodies (for example, humanized murine antibodies), heteroconjugate antibodies (such as, bispecific antibodies). See also, Pierce Catalog and Handbook, 1994-1995 (Pierce Chemical Co., Rockford, 111.); Kuby, J., Immunology, 3rd Ed., W.H. Freeman &amp; Co., New York, 1997. 
     In particular, the term “antibody” refers to a polypeptide ligand comprising at least a light chain and heavy chain immunoglobulin variable region which specifically recognizes and binds an epitope of an antigen. Antibodies are composed of a heavy and a light chain, each of which has a variable region, termed the variable heavy (VH) region and the variable light (VL) region. Together, the VH region and the VL region are responsible for binding the antigen recognized by the antibody. Typically, the antibody of the present invention has heavy (H) chains and light (L) chains interconnected by disulfide bonds. The term “light chain” as used herein includes a full-length light chain and fragments thereof having a sufficient variable region sequence to confer binding specificity. A full-length light chain includes a variable region domain, V L , and a constant region domain, C L . The variable region domain of the light chain is at the amino-terminus of the polypeptide. Light chains include kappa chains and lambda chains. The term “heavy chain” includes a full-length heavy chain and fragments thereof having sufficient variable region sequence to confer binding specificity. A full-length heavy chain includes a variable region domain, V H , and three constant region domains, C H 1, C H 2, and C H 3, The V H  domain is at the amino-terminus of the polypeptide, and the C H  domains are at the carboxyl-terminus, with the C H 3 being closest to the carboxy-terminus of the polypeptide, 
     There are five main heavy chain classes (or isotypes) which determine the functional activity of an antibody molecule: IgM, IgD, IgG, IgA and IgE. Each heavy and light chain contains a constant region and a variable region (the regions are also known as “domains”). In combination, the heavy and the light chain variable regions specifically bind the antigen. Light and heavy chain variable regions contain a “framework” region interrupted by three hypervariable regions, also called “complementarity-determining regions” or “CDRs”. The CDRs are primarily responsible for binding to an epitope of an antigen. The CDRs of each chain are typically referred to as CDR1, CDR2, and CDR3, numbered sequentially starting from the N-terminus, and are also typically identified by the chain in which the particular CDR is located. Thus, a VH CDR3 is located in the variable domain of the heavy chain of the antibody in which it is found, whereas a VL CDR1 is the CDR1 from the variable domain of the light chain of the antibody in which it is found. An antibody that binds CSF-1R will have a specific VH region and the VL region sequence, and thus specific CDR sequences. 
     The antibody, or fragment thereof, of the present invention may be a single chain antibody, an IgD antibody, an IgE antibody, an IgM antibody, an IgG antibody and fragments thereof. For example, the antibody may be an IgG antibody such as an IgG1 antibody; an IgG2 antibody; an IgG3 antibody; or an IgG4 antibody. In an embodiment, the antibody, or fragment thereof, has been produced recombinantly. 
     Also encompassed by the present invention are fragments of the monoclonal antibody of the present invention. The fragment shall be an immunologically functional fragment, i.e. an antigen-binding fragment. Accordingly, the fragment of the monoclonal antibody of the present invention shall be capable of the binding CSF-1R, such as human CSF-1R. Accordingly, the term “immunologically functional fragment” of an antibody, as used herein, refers to a portion of an antibody that lacks at least some of the amino acids present in a full-length chain but which is capable of specifically binding to CSF-1R. Immunologically functional immunoglobulin fragments include Fab, Fab′, F(ab′) 2 , and Fv fragments. How to produce antigen-binding fragments is well-known in the art. For example, the fragments can be produced by enzymatic cleavage of an antibody of the present invention. In addition, the fragments can be generated by synthetic or recombinant techniques. Fab fragments are preferably generated by papain digestion of an antibody, Fab′ fragments by pepsin digestion and partial reduction, F(ab′)2 fragments by pepsin digestion. Fv fragments are preferably produced by molecular biology techniques. 
     The fragment of an antibody may also be a diabody, which are small antibody fragments with two antigen-binding sites. Diabodies preferably comprise a heavy chain variable domain connected to a light chain variable domain in the same polypeptide chain. 
     The antibody of the present invention is preferably a monoclonal antibody. As used herein, the term “monoclonal antibody” refers to an antibody produced by a single clone of B-lymphocytes or by a cell into which the light and heavy chain genes of a single antibody have been transfected. Monoclonal antibodies are produced by methods known to those of skill in the art, for instance by making hybrid antibody-forming cells from a fusion of myeloma cells with immune spleen cells. 
     In an embodiment, the antibody of the present invention is an isolated antibody. Thus, the antibody shall be an antibody which has been purified. Purification of an antibody can be achieved by methods well-known in the art such as Size Exclusion Chromatography (SEC). Accordingly, the antibody shall have been isolated from the cells in which the antibody was produced. In some embodiments, an isolated antibody is purified to greater than 70% by weight of antibody as determined by, for example, the Lowry method, and in some embodiments, to greater than 80%, 90%, 95%, 96%, 97%, 98% or 99% by weight. In one preferred embodiment the isolated antibody according to the present invention is purified to greater than 90% purity as determined by SDS-PAGE under reducing conditions using Coomassie blue staining for protein detection. 
     The monoclonal antibody of the present invention, or fragment thereof, shall specifically bind to the CSF-1R polypeptide, e.g. to the human CSF-1R polypeptide. The expression “binding” and “specifically binding” are well understood and are used to indicate that an antibody (or fragment thereof) does not significantly bind to other biomolecules. 
     Preferably, the antibody of the present invention (or fragment thereof) shall specifically bind to the intracellular domain of the CSF-1R polypeptide, in particular to the kinase domain. The epitope of the monoclonal antibody, or fragment thereof, preferably comprises a sequence as shown in SEQ ID NO: 1 (YKNIHLEKKY). SEQ ID NO: 1 corresponds to the amino acids 699 to 708 of human CSF-1R (see SEQ ID NO: 10). Thus, the monoclonal antibody of the present invention, or the fragment thereof, shall specifically bind to this region. Preferably, at least one of the two Tyrosine residues of said epitope is phosphorylated, i.e. the Tyrosine residue at position 699 or the Tyrosine residue at position 708. More preferably, both Tyrosine residues of said epitope are phosphorylated, i.e. the Tyrosine residue at position 699 and the Tyrosine residue at position 708. Accordingly, it is envisaged that the antibody of the present invention, or fragment thereof, binds the human CSF-1R polypeptide, wherein the Tyrosine residue at position 699 and/or the Tyrosine residue at position 708 is/are phosphorylated. 
     The term “epitope” denotes a protein determinant capable of specifically binding to an antibody. Thus, the term preferably refers to the portion of the CSF-1R polypeptide (such as the human CSF-1R polypeptide) capable of being specifically bound by the antibody of the present invention (or the fragment thereof). Epitopes usually consist of chemically active surface groupings of molecules such as amino acids and usually epitopes have specific three-dimensional structural characteristics, as well as specific charge characteristics. Conformational and nonconformational epitopes are distinguished in that the binding to the former but not the latter is lost in the presence of denaturing solvents. 
     In a preferred embodiment, the antibody of the present invention or the fragment thereof is linked to a detectable label. A detectable label as described herein is preferably a label which is not naturally linked to an antibody or antigen-binding fragment thereof. Thus, the detectable label is preferably heterologous with respect to the antibody. Suitable labels are any labels detectable by an appropriate detection method. In an embodiment said detectable label is an enzyme, biotin, a radioactive label, a fluorescent label, a chemiluminescent label, an electrochemiluminescent label, a gold label, or a magnetic label. 
     Enzymatic labels include e.g. horseradish peroxidase, alkaline phosphatase, beta-galactosidase, and luciferase. The substrates for these enzymes are well-known in the art. Suitable substrates for detection include di-amino-benzidine (DAB), 3,3′-5,5′-tetramethylbenzidine, NBT-BCIP (4-nitro blue tetrazolium chloride and 5-bromo-4-chloro-3-indolyl-phosphate). A suitable enzyme-substrate combination may result in a colored reaction product, fluorescence or chemoluminescence, which can be measured according to methods known in the art. Fluorescent labels, e.g., include 5-carboxyfluorescein, fluorescein isothiocyanate, rhodamine, tetramethylrhodamine, Cy2, Cy3, and Cy5, fluorescent proteins such as GFP (Green Fluorescent Protein), Texas Red and the Alexa dyes. Radioactive labels, e.g., include radioactive isotopes of iodide, cobalt, selenium, tritium, carbon, sulfur and phosphorous. A radioactive label can be detected by any method known and appropriate, e.g. a light-sensitive film or a phosphor imager. Magnetic labels e.g. include paramagnetic and superparamagnetic labels. Chemiluminescent labels of use may include luminol, isoluminol, an aromatic acridinium ester, an imidazole, an acridinium salt or an oxalate ester. 
     The definition and explanations given herein above, preferably, apply mutatis mutandis to the following. 
     The antibody of the present invention, or antigen-binding fragment thereof, is useful in methods relating to the localization and/or quantitation of CSF-1R polypeptide. For example, the antibody, or fragment thereof, allows for determining the amount of the CSF-1R polypeptide in a sample, for use in diagnostic methods, or for imaging the CSF-1R polypeptide. 
     Accordingly, the present invention is directed to a method for detecting CSF-1R in a sample, comprising
         (a) contacting a sample comprising CSF-1R with the monoclonal antibody, or fragment thereof, of any one of the present invention, thereby forming a complex comprising CSF-1R and said monoclonal antibody, or fragment thereof, and   (b) detecting the complex formed in step (a), thereby detecting CSF-1R in said sample.       

     The “subject” as referred to herein is, preferably, a mammal. Mammals include, but are 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). Preferably, the subject is a mammalian subject, such as a human subject. In some aspects of the method, the sample is obtained from a subject that is diagnosed as having, suspected as having, or at risk of having cancer. 
     The term “sample” as used herein is intended to include tissues, cells and biological fluids isolated from a subject, as well as tissues, cells, and fluids present within a subject. Biological samples of the present disclosure include, e.g., but are not limited to, whole blood, plasma, semen, saliva, tears, urine, fecal material, sweat, buccal, skin, cerebrospinal fluid, and hair. Biological samples can also be obtained from biopsies of internal organs or from cancers. 
     In an embodiment, the sample contains cancer cells. Cancer cells are cells that have undergone a malignant transformation that makes them pathological to the patient. The term “cancer cell”, as used herein, includes not only a primary cancer cell, but also any cell derived from a cancer cell ancestor. This includes metastasized cancer cells, and in vitro cultures and cell lines derived from cancer cells. 
     Preferably, the sample containing cancer cells is biopsy tissue containing cancer cells. Thus, the sample has been obtained from a subject who suffers from cancer. 
     In accordance with the present invention, the sample has been obtained from a subject who has been contacted with candidate compound for the treatment of cancer. Thus, said candidate compound has been administered to the subject, in particular a subject suffering from cancer, before obtaining the sample to be tested. Alternatively, the sample has been contacted with a candidate compound for the treatment of cancer. 
     In an embodiment, the candidate compound for the treatment of cancer is an inhibitor of CSF-1R such as a small molecule inhibitor or a monoclonal antibody which binds CSF-1R, such as a monoclonal antibody which binds the extracellular domain of CSF-1R. 
     In an embodiment, the inhibitor of CSF-1R is selected from xidartinib, PLX7486, ARRY-382, JNJ-40346527, BLZ945, Emactuzumab, AMG820, and IMC-CS4 (see Cannarile et al., 2017 Journal for Immunotherapy of Cancer. 5 (1): 53). 
     In an embodiment of the above method, the detection of CSF-1R is the quantitative detection of CSF-1R. Thus, the amount of the CSF-1R in the sample is determined. The determined amount of CSF-1R may be compared to the amount of CSF-1R in a control biological sample. Thus, it may be e.g. assessed whether the amount of CSF-1R in the test sample is increased or decreased as compared to the control sample. 
     In an alternative embodiment of the above method, the detection of CSF-1R is the immunohistochemical detection of CSF-1R. Thus, CSF-1R is identified within the context of intact cells by labeling the test sample with the antibody (of antigen-binding fragment thereof) of the present invention in a manner that can be visualized on a microscope. By identifying CSF-1R in the context of a tissue environment or cellular environment, spatial relationships between the biomarkers and other morphological or molecular features of the cell or tissue sample can be elucidated, which may reveal information that is not apparent from other molecular or cellular techniques. 
     For detecting CSF-1R, the antibody of the present invention (or fragment thereof) may comprise a detectable label as described elsewhere herein. 
     The present invention is further directed to the in vitro use of the monoclonal antibody, or fragment thereof, of the present invention for the detection of CSF-1R, such as human CSF-1R in a sample. 
     The term “sample” and “subject” has been defined above. The sample is a cancer cell or cancer tissue. The definitions apply accordingly. As described above, the sample may have been contacted with a candidate compound for the treatment of cancer. Alternatively, the sample has been obtained from a subject who has been contacted with said candidate compound. 
     The present invention also relates to a complex comprising the monoclonal antibody, or fragment thereof, of the present invention and CSF-1R. Typically, the monoclonal antibody, or fragment thereof, is bound to CSF-1R (such as human CSF-1R) in said complex. 
     In an embodiment of the method and use of the present invention, the native form of CSF-1R (such as human CSF-1R) is detected. Thus, undenatured CSF-1R is detected. In an alternative embodiment, denatured CSF-1R is detected. Accordingly, the sample may have been subjected to at least one pre-treatment step which results in the denaturation of CSF-1R. E.g. the sample may have been subjected to heat, or at least one denaturing agent has been added to the sample. 
     The present invention also relates to a host cell producing the antibody of the present invention, or the antigen-binding fragment thereof. In a preferred embodiment, the host producing the antibody of the present invention is a hybridoma cell. Moreover, the host cell may be any kind of cellular system which can be engineered to generate the antibodies according to the current invention. For example, the host cell may be an animal cell, in particular a mammalian cell. In one embodiment HEK293 (human embryonal kidney cells) such as HEK 293-F cells as used in the Examples section, or CHO (Chinese hamster ovary) cells are used as host cells. In another embodiment, the host cell is a non-human animal or mammalian cell. 
     The host cell preferably comprises at least one polynucleotide encoding for the antibody of the present invention, or fragment thereof. For example, the host cell comprises at least one polynucleotide encoding for the light chain of the antibody of the present invention and at least one polynucleotide encoding the heavy chain of the antibody of the present invention. Said polynucleotide(s) shall be operably linked to a suitable promoter. 
     The invention further relates to a pharmaceutical composition comprising the monoclonal antibody, or fragment thereof, of the invention and a pharmaceutically acceptable diluent, solvent, carrier, salt and/or adjuvant. 
     The invention provides for an in vivo or in vitro method for decreasing CSF-1R expression in a target cell which is expressing CSF-1R, said method comprising administering an the monoclonal antibody, or fragment thereof, or pharmaceutical composition of the invention in an effective amount to said cell. 
     The invention provides for a method for treating or preventing a disease comprising administering a therapeutically or prophylactically effective amount of the monoclonal antibody, or fragment thereof, or pharmaceutical composition of the invention to a subject suffering from or susceptible to the disease. In some embodiments, the disease is cancer. 
     The invention provides monoclonal antibody, or fragment thereof, or pharmaceutical composition of the invention for use in medicine. 
     The invention provides for the monoclonal antibody, or fragment thereof, or pharmaceutical composition of the invention for use in the treatment or prevention of a cancer. 
     The invention provides for the use of the monoclonal antibody, or fragment thereof, or pharmaceutical composition of the invention, for the preparation of a medicament for treatment or prevention of cancer. 
    
    
     
       The Figures show: 
         FIG. 1  Circular Dichroism Analyses. Temperature ramp up/down experiment with the TtSlyD-CSF1R immunogen. TtSlyD-CSF1R is at least stable until 60° C. and restructures when cooling. 
         FIG. 2  Circular Dichroism Analyses of the immunogen TtSlyD-CSF1R before and after heating/cooling. TtSlyD-CSF1R restructures after thermal denaturation. 
         FIG. 3  Biacore Sensorgram showing concentration-dependent kinetics of captured antibody 1H11 versus phosphorylated TtSlyD-CSF1R as analyte in solution, Overlay of analyte concentrations and Langmuir Fitting model (straight black lines). Affinity K D  0.2 nM, k a  5.78 E+05 1/Ms, k d  1.22 E-04 1/s. 
         FIG. 4  Biacore Sensorgram showing an overlay of 300 nM single analyte concentration injections of four analytes in solution. Highest signal amplitude was found with the analyte TtSlyD-CSF1R (dashed line), Second highest signal response with the analyte pY723 phosphorylated peptide CSF1R[716-729] (thick black line). The negative control analytes are TtSlyDsh3 and the non-phosphorylated peptide CSF1R[716-729] (grey) with just background binding signal level. Antibody 1H11 shows phosphotyrosine-specific epitope binding properties. 
         FIG. 5  CelluSpots™ epitope mapping technology. Right: glass slide with CSF-1R 15-mer peptides in duplicate. Left: CSF-1R peptide sequences are given as single amino acid code. pY means phosphorylated tyrosin: 
       
         
           
             
                 
              
                 
                   SEQ ID NO: 13: P-E-G-G-V-D-pY-K-N-I-H-L-E-K-K, 
                 
                 
                     
                 
                 
                   SEQ ID NO: 14: E-G-G-V-D-pY-K-N-I-H-L-E-K-K-pY 
                 
                 
                     
                 
                 
                   SEQ ID NO 15: G-G-V-D-pY-K-N-I-H-L-E-K-K-pY-V 
                 
                 
                     
                 
                 
                   SEQ ID NO 16: G-V-D-pY-K-N-I-H-L-E-K-K-pY-V-R 
                 
                 
                     
                 
                 
                   SEQ ID NO 17: V-D-pY-K-N-I-H-L-E-K-K-pY-V-R-R 
                 
                 
                     
                 
                 
                   SEQ ID NO 18: D-pY-K-N-I-H-L-E-K-K-pY-V-R-R-D 
                 
                 
                     
                 
                 
                   SEQ ID NO 19: pY-K-N-I-H-L-E-K-K-pY-V-R-R-D-S 
                 
                 
                     
                 
                 
                   SEQ ID NO 20: K-N-I-H-L-E-K-K-pY-V-R-R-D-S-G 
                 
                 
                     
                 
                 
                   SEQ ID NO 21: N-I-H-L-E-K-K-pY-V-R-R-D-S-G-F 
                 
              
             
           
         
           
           
             
               The 1H11 epitope sequence was determined by a single amino acid step analysis through the CSF-1R sequences. 
             
           
         
      
         FIG. 6  IHC double stain. As compared to other antibodies that were isolated in the studies underlying the present invention that showed only a weak staining (not shown), the antibody 1H11 showed a very strong staining. 
         FIG. 7  Western-Blot analysis of selected antibodies. (lane 1: Western Standard; lane 2: NIH3T3 wt; lane 2 NIH 3T3+CSF1 K4; lane 4: NIH 3T3+CSF1 K8, lane 5: protein standards). Antibody 1H11 showed the strongest staining and overexposed the blot. The other tested antibodies showed a weak staining only. 
     
    
    
     EXAMPLES 
     The invention will be merely illustrated by the following Examples. The said Examples shall, whatsoever, not be construed in a manner limiting the scope of the invention. 
     Example 1: Preparation of the Immunogen 
     TtSlyD-CSF1R and TtSlyD-sh3 ORFs were synthetized by GeneArt and delivered within an ampicillin resistance cloning vector. TtSlyD-CSF1R encodes the amino acids sequence: 
     
       
         
           
               
               
            
               
                   
                 &gt;TtSlyD-CSF1R 
               
               
                   
                 (SEQ ID NO: 11) 
               
               
                   
                 MRSKVGQDKV VTIRYTLQVE GEVLDQGELS YLHGHRNLIP 
               
               
                   
                   
               
               
                   
                 GLEEALEGRE EGEAFQAHVP AEKAYGAGSM LGPSLSPGQD 
               
               
                   
                   
               
               
                   
                 PEGGVDYKNI HLEKKYVRRD SGFSSQGVDT YVEMRPVSTS 
               
               
                   
                   
               
               
                   
                 SNDSFSEQDL DKEDGRPGSS GKDLDFQVEV VKVREATPEE 
               
               
                   
                   
               
               
                   
                 LLHGHAHGGG SRPLLPPLPG GGSRKHHHHH HHH 
               
            
           
         
       
     
     TtSlyD-sh3 was applied as insertion free control protein and encodes the amino acid sequence: 
     
       
         
           
               
               
            
               
                   
                 &gt;TtSlyDsh3 
               
               
                   
                 (SEQ ID NO: 12) 
               
               
                   
                 MRSKVGQDKV VTIRYTLQVE GEVLDQGELS YLHGHRNLIP 
               
               
                   
                   
               
               
                   
                 GLEEALEGRE EGEAFQAHVP AEKAYGAGSG SSGKDLDFQV 
               
               
                   
                   
               
               
                   
                 EVVKVREATP EELLHGHAHG GGSRPLLPPL PGGGSRKHHH 
               
               
                   
                   
               
               
                   
                 HHHHH 
               
            
           
         
       
     
     Restriction Enzymes and “Rapid DNA Ligation Kit” were obtained from Roche.  E. coli  XL1-Blue Supercompetent Cell and BL21 Codon Plus were obtained from Stratagene. To purify the DNA “High Pure Plasmid Isolation Kit” and “High Pure PCR Product Purification Kit” (Roche) were used. pQE80L was used as cloning and expression vector. 
     The bacteria were grown in Lysogeny Broth (LB: 5 g/l Yeast Extract, 10 g/l Trypton, 5 g/l NaCl, pH7.0) with selection antibiotic (100 μg/ml Ampicillin). For improved growing during protein expression LB medium was exchanged to Super Broth medium (SB: 20 g/l Yeast Extract, 32 g/l Trypton, 5 g/l NaCl, pH7.0). 
     TtSlyD-CSF1R was released from the delivering vector with EcoRI and HindIII and ligated into the expression vector pQE80-L, the later digested with EcoRI and HindIII. After transformation of  E. coli  XL1-Blue bacteria, plasmidic DNA was obtained and transformed in  E. coli  BL21 Codon Plus. In brief, for recombinant expression and purification, cells were grown in SB medium at 37° C. When the exponential phase was reached, TtSlyD variants expression was induced using 0.5 mM isopropil-β-D-thiogalactoside (IPGT) for at least 3 h. Inclusion bodies from the cell pellet were resuspended in chilled sodium phosphate buffer (pH8.0) containing 7.0M GdmCl, and stirred for 2 h until complete cell lysis. The precleared lysate was applied into a Ni-NTA column and 10-15 column volumes of wash buffer (phosphate buffer pH8.0, 7.0M GdmCl, 10 mM imidazole) were applied. To avoid reactivation of copurifying proteases, a protease inhibitors cocktail (Complete EDTA-free, Roche) was included in the refolding buffer (phosphate buffer pH8.0, 20 mM imidazole). A total of 20-25 column volumes of refolding buffer were applied slowly over night. The inhibitors cocktail was removed, with 5-10 column volumes of further washing with refolding buffer, before eluting the protein in a gradient of 250 mM imidazole. Protein containing fractions were pooled and purified again through a size-exclusion chromatography column (HiLoad™ 26/60 Superdex™ 75 size exclusion chromatography column, Amersham Pharmacia) in Storage Buffer (50 mM KH 2 P04 pH6.95, 100 mM KCl, 0.5 mM EDTA). Only monomer containing fractions were recovered and assessed for purity in SDS denaturizing gels. Novex® NuPAGE® SDS-PAGE Gel Systems (Invitrogen) were used for Western Blot analysis. Commassie-like protein staining was performed using SimplyBlue™ Safe-Stain (Invitrogen). Protein concentration measurements were performed with a DU®7400 Spectrophotometer (Beckman Coulter™). The molar extinction coefficients (ε 280 ) for fusion proteins were calculated by bioinformatics 
     Example 2: Circular Dichroism Spectra Analysis 
     Protein concentration measurements were performed with a DU®7400 Spectrophotometer (Beckman Coulter™). The molar extinction coefficients (ε 280 ) for fusion proteins were calculated by bioinformatics. 
     Near-UV CD spectra were recorded using a Jasco-720 spectropolarimeter with a thermostatic cell holder set to 20° C. and converted to mean residue ellipticity. The buffer was 50 mM potassium phosphate (pH6.95), 100 mM KCl and 0.5 mM EDTA. The spectra was recorded between 330-250 nm with a path length of 0.2 cm, and the protein concentration was 500 μM. The bandwidth was 1 nm, the scanning speed was 20 nm/min at a resolution of 0.5 nm, and the response was 1 s. To improve the signal to noise ratio, spectra were measured nine times and averaged. FAr-UV CD spectra were recorded using a Jasco-720 spectropolarimeter with a thermostatic cell holder set to 20° C. and converted to mean residue ellipticity. The buffer was 10 mM potassium phosphate (pH6.95) and 10 mM KCl. The spectra was recorded between 250-190 nm with a path length of 0.2 cm, and the protein concentration was 5 μM. The bandwidth was 1 nm, the scanning speed was 20 nm/min at a resolution of 0.5 nm, and the response was 1 s. To improve the signal to noise ratio, spectra were measured nine times and averaged. 
     For the thermal unfolding transitions of fusion proteins, the proteins were measured at 500 μM in 50 mM potassium phosphate (pH6.95), 100 mM KCl and 0.5 mM EDTA. Thermally induced unfolding-refolding transitions were recorded at 278 nm, and the path length of the cuvette was 0.2 cm. Heating and cooling rages were 1° C./min, and the response time was 4 s. To assess the reversibility of the unfolding, near-UV CD spectra of the fusion proteins were recorded before and after the thermally induced unfolding-refolding cycle. 
     Protein concentration measurements were performed with a DU®7400 Spectrophotometer (Beckman Coulter™). The molar extinction coefficients (ε 280 ) for fusion proteins were calculated by bioinformatics according to Gasteiger et al 2005. 
     Fluorescence spectra were recorded using a Cary Eclipse fluorescence spectrophotometer (Varian) with a thermostatic cell holder set to 20° C. The buffer was 50 mM potassium phosphate (pH6.95), 100 mM KCl and 0.5 mM EDTA. The samples were excited at 280/290/295 nm and the spectra were recorded between 300-425 nm with a path length of 1 cm. The protein concentration was 10-30 μM. The bandwidth was 5 nm, the scanning speed was 120 nm/min at a resolution of 1 nm, and the response was 0.5 s. 
     For the thermal unfolding transitions of fusion proteins, the same concentration and buffer were used. The full spectra were recorded for thermally induced unfolding transitions, with the same specifications as for single measurements. Heating intervals were set to 5° C., and the stabilization period between temperature changes was set to 10 min. To assess the reversibility of the unfolding, fluorescence spectra of the fusion proteins were recorded before and after the thermally induced unfolding-refolding cycle. 
     Example 3: Phosphorylation and Purification of TtSlyD-CSF1R 
     Buffer components were obtained from Merck, Roche and Sigma. Src (1-530) active kinase was purchased from Upstate (Millipore). According to manufacture instructions Src kinase was diluted (20 mM MOPS-NaOH pH7.0, 1 mM EDTA, 0.01% Brij-30, 5% glycerol, 0.1% 3-mercaptoethanol and 1 mg/ml BSA), aliquoted and stored at −80° C. Novex® NuPAGE® SDS-PAGE Gel Systems (Invitrogen) were used for Western Blot analysis. To detect phosphorylated protein, several pan-pTyr primary antibodies were used: P-Tyr-4G10 (Millipore), P-Tyr-100 and P-Tyr-102 (Cell Singaling), and an HRP-conjugated goat-anti-mouse-IgG (Invitrogen) as secondary. The results were analyzed by ChemiDoc™ MP (Bio-Rad), incubating the membrane with Lumi-Light PLUS Western Blotting Substrate (IRoche). 
     4.5 mg TtSlyD-CSF1R was diluted to a 60 μM concentration with reaction buffer (10 mM MOPS-NaOH pH7.0, 50 mM NaCl, 0.3 mM EDTA, 0.001% Brij-30, 0.5% glycerol, 10 mM MgAc, 0.1 mM ATP, 0.25 mM orthovanadate and 0.1 mg/ml BSA). 4 units of Src were added (1.97 U/μg) and the reaction was incubated for 2 h at 30° C. Afterwards the reaction was stopped by chelating Mg 2+  cations using EDTA. To remove the buffer and contaminating proteins, the solution was loaded in a HiLoad™ 16/60 Superdex™ 200 size exclusion chromatography column (Amersham, Pharmacia) using sterile-filtrated PBS pH6.95 as a sheath solution. TtSlyD-CSF1R containing fractions were recovered and the protein was concentrated using Ultracell™ 10 k Amicon (Millipore). 81% of the initial protein was recovered. 
     Example 4: Rabbit Monoclonal Antibody Production 
     Rabbits were immunized subcutaneous each 30 days with 100 μg antigen. Serum was taken starting at day 45 and the antibody titers against the antigens were tested. After 2 month the immunogen titer was over 200.000. Peripheral blood was monthly taken 5 to 6 days after the boost. The blood was treated with citrate to avoid coagulation, and was freshly processed the same day. The Peripheral Blood Mononuclear Cells (PBMCs) were required for either obtaining antibody-producing B-cells or macrophages for their secreted grown factors. PBMCs were obtained from peripheral rabbit blood and antigen specific monoclonal antibodies were generated as it is described in Seeber et al. (2014), PLoS One. 2014 Feb. 4; 9(2). 5.10e7 PMBCs/ml were resuspended in FACS Puffer (PBS+0.1% BSA) with 250 nM of the biotinylated antigen. After 15-20′ incubation at 4° C., the cells were washed with 40 ml PBS, and resuspended to 10e8 PMBCs/ml in Labeling Buffer (PBS+2 mM EDTA). 10% volume of Streptavidin Beads was added (MACS Miltenyi Biotec) and they were incubated 15-20′ at 4° C. The cells were washed with 40 ml PBS, and resuspended to 2.10e8 PMBCs/ml in MACS Buffer (PBS+2 mM EDTA+0.5% BSA). The suspension was loaded in a preequilibrated MS Columns (MACS Mitenyi Biotec), washed with three volumes of MACS Buffer, and the bound cells were recovered in 1 ml MACS Buffer. To discriminate between cell types, the recovered cells were stained with a fluorescent antibody against rabbit IgG (AbD Serotec), and the IgG positive cells were single cell sorted using a FACSAria I cell sorter (BD Biosciences). The cells were incubated in B-cell medium as described in Seeber et al. for one week. After one week, the supernatant of the clones were tested for IgG production and antigen specificity using HitELISA techniques. The positive clones were selected and stored at −80° C. with RNA lysis buffer. HitELISAs with cell culture supernatans and purified mAbs. ELISA plates (Roche) were coated with 100-250 ng/ml of antigens in carbonate buffer, pH9.6. Biotinylated antigens were bound directly to Streptavidin coated plates (Roche) using the same antigen concentration. After washing, plates were blocked with Incubation Buffer (IB: 1% BSA 0.05% Tween-PBS). The plates were incubated with cell supernatants or purified mAbs diluted with IB. After washing, the plates were developed by incubation for 1 h with HRP-conjugated F(ab′)2 fragment goat anti-rabbit IgG (Dianova) and adding 100 μl ABTS solution (Roche). Optical densities were measured at the appropriate wavelength using an ELISA microplate reader. IgG concentration sandwich-ELISA. ELISA plates were coated with 3 μg/ml of goat anti-rabbit IgG in carbonate buffer, pH9.6. After washing, plates were blocked with IB. The plates were incubated with cell supernatants diluted in D3. Subsequent ELISAs were performed similarly as described above. 
     The B-cell mRNA was purified with RNeasy® Plus Mini Kit (Qiagen®) from the positive single memory B-cells cultures frozen at −80° C. Reverse transcription was performed with Transcription Universal cDNA Master (Roche). The cDNA plates were stored at −20° C. until further use. The IgH, Igλ and Igκ variable genes were amplified independently by PCR with the appropriate primers, starting from 2 μl cDNA as a template with Expand High Fidelity PCR System (Roche). The purified single amplified bands and the plasmids containing the IgG constant regions were digested with T4 DNA Polymerase (Roche) to generate 5′ overhangs, followed by RecA treatment (NE Biolabs) to be religated by Sequence and Ligation-Independent Cloning (SLIC). The recombined plasmids were transformed and tested for correct insertion cloning using standard digestion and sequencing protocols. 
     Full length IgG mAbs were produced by transient cotransfection of the paired heavy and light chain TIPE plasmids into FreeStyle 293-F cells (Invitrogen) grown in serum-free FreeStyle™ 293 Expression Medium (Gibco®Invitrogen) using 293-Free™ Transfection Reagent (Novagen®). Cells were cultivated one week at 37° C./5-8% CO 2  with continuous shaking at 180 rpm. The supernatants were collected by centrifugation and stored at −20° C. 
     Example 5: Interaction Analysis 
     A Biacore B3000 instrument (GE Healthcare) was used to kinetically assess the rabbit antibodies for kinetics and binding specificity for TtSlyD-CSF1R. A CMS series sensor was mounted into the system and was normalized in HBS-ET buffer (10 mM HEPES pH 7.4, 150 mM NaCl, 3 mM EDTA, 0.005% w/v Tween 20) according to the manufacturer&#39;s instructions. The sample buffer was the system buffer supplemented with 1 mg/ml CMD (Carboxymethyldextran, Sigma #86524). The system operated at 25° C. 10000 RU GAR&lt;F(ab)2&gt; (relative units of goat anti rabbit F(ab)2/Jackson Laboratories, cat. No. 100018) were immobilized according to the manufacturer&#39;s instructions using EDC/NHS chemistry on all flow cells. The sensor was saturated with 1M ethanolamine. The binding activity of the antibodies against the analytes were kinetically tested. Analytes in solution were two 2 kDa peptides CSF1R (716-729) with Y723 phosphorylated and non-phosphorylated, a 14 kDa TtSlyDsh3 control protein with a CSF1R unrelated insertion domain and the 21 kDa TtSlyD-CSF1R protein. Antibodies were captured by a 2 min injection at 10 μl/min of cell culture HEK supernatant diluted 1:2 in sample buffer. The flow rate was set to 100 μl/min. The analyte was injected at different concentration steps of 0 nM, 1.1 nM, 3.7 nM, 11.1 nM, 33.1 nM, 100 nM and 300 nM for 2 min. The dissociation was monitored for 5 min. Kinetic signatures were monitored and evaluated using the Biaevaluation Software and a binary Langmuir Fitting model with R MAX  local. Acidic regeneration of the sensor surface was achieved using three consecutive injections of 10 mM Glycine pH 1.7 at 30 μl/min for 60 sec. 
     Example 6: Linear Epitope Mapping 
     Peptide based epitope mappings were carried out as described and commercially offered by Intavis, Cologne Germany, http://www.intavis.com) using the CelluSpots™ technology. Epitope mappings were carried out by means of a library of overlapping, immobilized peptide fragments (length: 15 amino acids) corresponding to the sequences of human CSF1R KID domain. Each peptide synthesized was shifted by one amino acid, i.e. it had 14 amino acids overlap with the previous and the following peptide, respectively. For preparation of the peptide arrays the Intavis CelluSpots™ technology was employed. In this approach, peptides are synthesized with an automated synthesizer (Intavis MultiPep RS) on modified cellulose disks which are dissolved after synthesis. The solutions of individual peptides covalently linked to macromolecular cellulose are then spotted onto coated microscope slides. The CelluSpots™ synthesis was carried out stepwise utilizing 9-fluorenylmethoxycarbonyl (Fmoc) chemistry on amino-modified cellulose disks in a 384-well synthesis plate. In each coupling cycle, the corresponding amino acids were activated with a solution of DIC/HOBt in DMF. Between coupling steps un-reacted amino groups were capped with a mixture of acetic anhydride, diisopropylethyl amine and 1-hydroxybenzotriazole. Upon completion of the synthesis, the cellulose disks were transferred to a 96-well plate and treated with a mixture of trifluoroacetic acid (TFA), dichloromethane, triisoproylsilane (TIS) and water for side chain deprotection. After removal of the cleavage solution, the cellulose bound peptides are dissolved with a mixture of TFA, TFMSA, TIS and water, precipitated with diisopropyl ether and re-suspended in DMSO. The peptide solutions were subsequently spotted onto Intavis CelluSpots™ slides using an Intavis slide spotting robot. 
     For linear epitope analysis, the slides prepared as described above were treated using the BenchMark XT Automated Slide Preparation System (Ventana). The slides were developed with OptiView DAB IHC Detection Kit plus OptiView Amplification Kit (Ventana), according to the standardized protocols. Briefly described, the slides were “wet-loaded” in the system, and blocked for 32 minutes with 1% BSA in Phosphate Buffer (PBS). The antibody was diluted to 1 μg/ml in Antibody Diluent (Ventana) and applied manually on the slide for 1 h at room temperature; both Amplifier and Amplification Multimer reagents were incubated for 8 minutes each without counterstain staining. To analyze the colorimetric staining, a ChemiDoc Analyzer (BioRAD) was used. 
     When a high signal was desired, the slides were treated manually with chemiluminiscent reagents. Briefly, the slides were washed with ethanol and then with Tris-buffered saline (TBS; 50 mM Tris, 137 mM NaCl, 2.7 mM KCl, pH 8) before blocking for 16 h at 4° C. with 5 mL 10× Western Blocking Reagent (Roche Applied Science), 2.5 g sucrose in TBS, 0.1% Tween 20. The slide was washed with TBS and 0.1% Tween 20 and incubated afterward with 1 μg/mL of the corresponding antibodies in TBS and 0.1% Tween 20 at ambient temperature for 2 h and subsequently washed with TBS+0.1% Tween 20. For detection, the slide was incubated with anti-rabbit/anti-mouse secondary HRP-antibody (1:20000 in TBS-T) followed by incubation with chemiluminescence substrate luminol and visualized with a Lumilmager (Roche Applied Science). ELISA-positive SPOTs were quantified and through assignment of the corresponding peptide sequences the antibody binding epitopes were identified. 
     Immunohistochemistry 
     Immunohistochemistry was performed using the BenchMark XT Automated Slide Preparation System (Ventana). The slides were developed with iVIEW DAB Detection Kit (Ventana), according to the standardized protocols. Briefly described, the slides were deparafined with Cell Conditioning 1 (CC1, Ventana), and blocked for 32 minutes with 1% BSA in Phosphate Buffer (PBS). The antibody was diluted to 1 μg/ml in Antibody Diluent (Ventana) and applied manually on the slide for 1 h at room temperature.