The invention relates to leptin fusion polypeptides and dimers; nucleic acid molecules
encoding said polypeptides and methods of treatment that use said polypeptides/dimers.
Cytokine receptors can be divided into three separate groups. Class 1 (referred to as
the haemotopoietin or growth hormone family) receptors are characterised by four
conserved cysteine residues in the amino terminal part of their extracellular domain and
the presence of a conserved Trp-Ser-Xaa-Trp-Ser motif in the C-terminal part. The
receptors consist of two polypeptide chains. Class I receptors can be sub-divided into the
GM-CSF sub-family (which includes IL-3, IL-5, GM-CSF, GCSF) and IL-6 sub-family
(which includes IL-6, IL-11 and IL-12). In the IL-6 sub-family there is a common
tranduscing subunit (gp130) that associates with one or two different cytokine subunits.
There is a further sub-family referred to as the IL-2 sub-family (includes IL-2, IL-4, IL-7,
IL-9 and IL-15. The repeated Cys motif is also present in Class 2 (interferon receptor
family) the ligands of which are α, β and γ interferons but lack the conserved Trp-Ser-
Xaa-Trp-Ser motif.
Human leptin is a 16kD protein hormone encoded by the lep gene in humans and the ob
gene in mice. Leptin acts through the leptin receptor which is a single transmembrane
receptor of the cytokine family. There is a single gene that encodes leptin in humans
which includes three exons and two introns and spans about 18kb of genomic DNA.
Leptin links nutritional status and the immune system to control, inter alia, appetite and
the immune function. The existence of mutations in either leptin or leptin receptor can
result in an obese phenotype with attendant secondary symptoms associated with obesity
(e.g. heart disease, diabetes type II). Leptin is mainly produced by adipose tissue in
proportion to the body mass index (BMI) and, at lower levels, by organs such as the
stomach and placenta. Leptin regulates body weight through inhibition of food intake and
stimulation of energy expenditure. Moreover, leptin affects both the innate and adaptive
immunity. On innate immunity, leptin modulates the activity of neutrophils, increases the
phagocytosis of monocytes/macrophages and enhances the secretion of inflammatory
mediators of the acute-phase response. On adaptive immunity, leptin promotes
proliferation and interleukin 2 (IL-2) secretion by naive T cells whereas on memory T
cells, it promotes the switch towards T helper 1 (Th1) immune response by increasing
interferon-γ (INF-γ) and tumor necrosis factor- a (TNF- α secretion).

1
If leptin expression and/or production is perturbed then the pathological manifestation of
disease is complicated with effects on energy metabolism and immune status. Apart from
the established linkage to obesity, reduction in leptin is associated with infertility,
osteoporosis and immune suppression.
This disclosure relates to the identification of leptin recombinant forms that have
improved pharmacokinetics (PK) and activity. The new leptin molecules have biological
activity, form dimers and have improved stability.
According to an aspect of the invention there is provided a nucleic acid molecule
comprising a nucleic acid sequence that encodes a polypeptide that has the activity of
leptin comprising a leptin polypeptide linked, directly or indirectly, to at least one leptin
binding domain of the leptin receptor polypeptide.
According to an aspect of the invention there is provided a fusion polypeptide comprising:
the amino acid sequence of the leptin polypeptide, or active part thereof linked, directly or
indirectly, to at least one leptin binding domain of the leptin receptor polypeptide.
In a preferred embodiment of the invention said fusion polypeptide comprises two leptin
binding domains.
In a further preferred embodiment of the invention said fusion polypeptide comprises an
immunoglobulin-like domain.
In a preferred embodiment of the invention said fusion polypeptide comprises at least
one cytokine-like homology domain; preferably two cytokine-like homology domains.
In a yet further preferred embodiment of the invention said fusion polypeptide comprises
at least one fibronectin III binding domain; preferably two fibronectin III binding domains.
In a preferred embodiment of the invention said fusion polypeptide comprises amino acid
residues 428-535 of SEQ ID NO: 41.
In a preferred embodiment of the invention said fusion polypeptide comprises amino acid
residues 536-635 of SEQ ID NO: 41.

In a preferred embodiment of the invention said fusion polypeptide comprises amino acid
residues 326-437 of SEQ ID NO: 41.
In a preferred embodiment of the invention said fusion polypeptide comprises amino acid
residues 62-178 of SEQ ID NO: 41.
In a preferred embodiment of the invention said fusion polypeptide comprises amino acid
residues 235-325 of SEQ ID NO: 41.
In a preferred embodiment of the invention said fusion polypeptide comprises amino acid
residues 639-732 of SEQ ID NO: 41.
In a preferred embodiment of the invention said fusion polypeptide comprises amino acid
residues 734-829 of SEQ ID NO: 41.
In a further preferred embodiment of the invention said fusion polypeptide comprises
amino acid residues 428-635 of SEQ ID NO: 41.
In a preferred embodiment of the invention said leptin polypeptide is linked to at least one
leptin binding domain of leptin receptor wherein said leptin polypeptide is positioned
amino-terminal to said leptin binding domain in said fusion polypeptide.
In a preferred embodiment of the invention said leptin polypeptide is linked to at least one
leptin binding domain of leptin receptor wherein said leptin polypeptide is positioned
carboxyl-terminal to said leptin binding domain in said fusion polypeptide.
In a preferred embodiment of the invention said leptin polypeptide is linked to at least one
binding domain of the leptin receptor polypeptide by a peptide linker; preferably a flexible
peptide linker.
In a preferred embodiment of the invention said peptide linking molecule comprises at
least one copy of the peptide Gly Gly Gly Gly Ser.

In a preferred embodiment of the invention said peptide linking molecule comprises 2, 3,
4, 5, 6, 7, 8, 9 or 10 copies of the peptide Gly Gly Gly Gly Ser.
Preferably said peptide linking molecule consists of 6 copies of the peptide Gly Gly Gly
Gly Ser.
Preferably said peptide linking molecule consists of 8 copies of the peptide Gly Gly Gly
Gly Ser.
In an alternative embodiment of the invention said polypeptide does not comprise a
peptide linking molecule and is a direct fusion of leptin polypeptide and at least one leptin
binding domain of the leptin receptor polypeptide.
According to an aspect of the invention there is provided a nucleic acid molecule
comprising a nucleic acid sequence selected from:
i) a nucleic acid sequence as represented in SEQ ID NO:3 ;
ii) a nucleic acid sequence as represented in SEQ ID NO:5;
iii) a nucleic acid sequence as represented in SEQ ID NO:7;
iv) a nucleic acid sequence as represented in SEQ ID NO:9;
v) a nucleic acid sequence as represented in SEQ ID NO:11;
vi) a nucleic acid sequence as represented in SEQ ID NO: 13;
vii) a nucleic acid sequence as represented in SEQ ID NO: 15;
viii) a nucleic acid sequence as represented in SEQ ID NO: 17;
ix) a nucleic acid sequence as represented in SEQ ID NO: 19;
x) a nucleic acid sequence as represented in SEQ ID NO:21;
xi) a nucleic acid sequence as represented in SEQ ID NO:23;
xii) a nucleic acid sequence as represented in SEQ ID NO:25;
xiii) a nucleic acid sequence as represented in SEQ ID NO:27;
a nucleic acid molecule comprising a nucleic sequence that hybridizes under stringent
hybridization conditions to SEQ ID NO: 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25 or 27 and
which encodes a polypeptide that has leptin receptor modulating activity.
In a preferred embodiment of the invention said nucleic acid molecule encodes a leptin
agonist.

In an alternative preferred embodiment of the invention said nucleic acid molecule
encodes a leptin antagonist.
Hybridization of a nucleic acid molecule occurs when two complementary nucleic acid
molecules undergo an amount of hydrogen bonding to each other. The stringency of
hybridization can vary according to the environmental conditions surrounding the nucleic
acids, the nature of the hybridization method, and the composition and length of the
nucleic acid molecules used. Calculations regarding hybridization conditions required for
attaining particular degrees of stringency are discussed in Sambrook et al., Molecular
Cloning: A Laboratory Manual (Cold Spring Harbor Laboratory Press, Cold Spring
Harbor, NY, 2001); and Tijssen, Laboratory Techniques in Biochemistry and Molecular
Biology—Hybridization with Nucleic Acid Probes Part I, Chapter 2 (Elsevier, New York,
1993). The Tm is the temperature at which 50% of a given strand of a nucleic acid
molecule is hybridized to its complementary strand. The following is an exemplary set of
hybridization conditions and is not limiting:
Very High Stringency (allows sequences that share at least 90% identity to hybridize)
Hybridization: 5x SSC at 65°C for 16 hours
Wash twice: 2x SSC at room temperature (RT) for 15 minutes each
Wash twice: 0.5x SSC at 65°C for 20 minutes each
High Stringency (allows sequences that share at least 80% identity to hybridize)
Hybridization: 5x-6x SSC at 65°C-70°C for 16-20 hours
Wash twice: 2x SSC at RT for 5-20 minutes each
Wash twice: 1x SSC at 55°C-70°C for 30 minutes each
Low Stringency (allows seguences that share at least 50% identity to hybridize)
Hybridization: 6x SSC at RT to 55°C for 16-20 hours
Wash at least twice: 2x-3x SSC at RT to 55°C for 20-30 minutes each.
In a preferred embodiment of the invention said nucleic acid molecule comprises or
consists of a nucleic acid seguence as represented in SEQ ID NO:3 .
In a preferred embodiment of the invention said nucleic acid molecule comprises or
consists of a nucleic acid seguence as represented in SEQ ID NO: 5.

In a preferred embodiment of the invention said nucleic acid molecule comprises or
consists of a nucleic acid sequence as represented in SEQ ID NO: 7.
In a preferred embodiment of the invention said nucleic acid molecule comprises or
consists of a nucleic acid sequence as represented in SEQ ID NO: 9.
In a preferred embodiment of the invention said nucleic acid molecule comprises or
consists of a nucleic acid sequence as represented in SEQ ID NO: 11.
In a preferred embodiment of the invention said nucleic acid molecule comprises or
consists of a nucleic acid sequence as represented in SEQ ID NO: 13.
In a preferred embodiment of the invention said nucleic acid molecule comprises or
consists of a nucleic acid sequence as represented in SEQ ID NO: 17.
In a preferred embodiment of the invention said nucleic acid molecule comprises or
consists of a nucleic acid sequence as represented in SEQ ID NO: 19.
In a preferred embodiment of the invention said nucleic acid molecule comprises or
consists of a nucleic acid sequence as represented in SEQ ID NO: 21.
In a preferred embodiment of the invention said nucleic acid molecule comprises or
consists of a nucleic acid sequence as represented in SEQ ID NO: 23.
In a preferred embodiment of the invention said nucleic acid molecule comprises or
consists of a nucleic acid sequence as represented in SEQ ID NO: 25.
In a preferred embodiment of the invention said nucleic acid molecule comprises or
consists of a nucleic acid sequence as represented in SEQ ID NO: 27.
According to an aspect of the invention there is provided a polypeptide encoded by the
nucleic acid according to the invention.

According to a further aspect of the invention there is provided a polypeptide comprising
or consisting of an amino acid sequence as represented in SEQ ID NO: 4, 6, 8, 10, 12,
14, 16, 18, 20, 22, 24, 26, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40.
According to an aspect of the invention there is provided a homodimer consisting of two
polypeptides wherein each of said polypeptides comprises:
i) a first part comprising leptin, or a receptor binding domain thereof,
optionally linked by a peptide linking molecule to
ii) a second part comprising at least one leptin binding domain or part
thereof, of the leptin receptor.
In a preferred embodiment of the invention said homodimer comprises two polypeptides
comprising or consisting of SEQ ID NO: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28,
29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40.
According to a further aspect of the invention there is provided a vector comprising a
nucleic acid molecule according to the invention.
In a preferred embodiment of the invention said vector is an expression vector adapted to
express the nucleic acid molecule according to the invention.
A vector including nucleic acid (s) according to the invention need not include a promoter
or other regulatory sequence, particularly if the vector is to be used to introduce the
nucleic acid into cells for recombination into the genome for stable transfection.
Preferably the nucleic acid in the vector is operably linked to an appropriate promoter or
other regulatory elements for transcription in a host cell. The vector may be a bi-
functional expression vector which functions in multiple hosts. By "promoter" is meant a
nucleotide sequence upstream from the transcriptional initiation site and which contains
all the regulatory regions required for transcription. Suitable promoters include
constitutive, tissue-specific, inducible, developmental or other promoters for expression in
eukaryotic or prokaryotic cells. "Operably linked" means joined as part of the same
nucleic acid molecule, suitably positioned and oriented for transcription to be initiated
from the promoter. DNA operably linked to a promoter is "under transcriptional initiation
regulation" of the promoter.

In a preferred embodiment the promoter is a constitutive, an inducible or regulatable
promoter.
According to a further aspect of the invention there is provided a cell transfected or
transformed with a nucleic acid molecule or vector according to the invention.
Preferably said cell is a eukaryotic cell. Alternatively said cell is a prokaryotic cell.
In a preferred embodiment of the invention said cell is selected from the group consisting
of; a fungal cell (e.g. Pichia spp, Saccharomyces spp, Neurospora spp); insect cell (e.g.
Spodoptera spp); a mammalian cell (e.g. COS cell, CHO cell); a plant cell.
According to a further aspect of the invention there is provided a pharmaceutical
composition comprising a polypeptide according to the invention including an excipient or
carrier.
In a preferred embodiment of the invention said pharmaceutical composition is combined
with a further therapeutic agent.
When administered the pharmaceutical composition of the present invention is
administered in pharmaceutically acceptable preparations. Such preparations may
routinely contain pharmaceutically acceptable concentrations of salt, buffering agents,
preservatives, compatible carriers, and optionally other therapeutic agents.
The pharmaceutical compositions of the invention can be administered by any
conventional route, including injection. The administration and application may, for
example, be oral, intravenous, intraperitoneal, intramuscular, intracavity, intra-articuar,
subcutaneous, topical (eyes), dermal (e.g a cream lipid soluble insert into skin or mucus
membrane), transdermal, or intranasal.
Pharmaceutical compositions of the invention are administered in effective amounts. An
"effective amount" is that amount of pharmaceuticals/compositions that alone, or together
with further doses or synergistic drugs, produces the desired response. This may involve
only slowing the progression of the disease temporarily, although more preferably, it
involves halting the progression of the disease permanently. This can be monitored by

routine methods or can be monitored according to diagnostic methods.
The doses of the pharmaceuticals compositions administered to a subject can be chosen
in accordance with different parameters, in particular in accordance with the mode of
administration used and the state of the subject (i.e. age, sex). When administered, the
pharmaceutical compositions of the invention are applied in pharmaceutically-acceptable
amounts and in pharmaceutically-acceptable compositions. When used in medicine salts
should be pharmaceutically acceptable, but non-pharmaceutically acceptable salts may
conveniently be used to prepare pharmaceutically-acceptable salts thereof and are not
excluded from the scope of the invention. Such pharmacologically and pharmaceutically-
acceptable salts include, but are not limited to, those prepared from the following acids:
hydrochloric, hydrobromic, sulfuric, nitric, phosphoric, maleic, acetic, salicylic, citric,
formic, malonic, succinic, and the like. Also, pharmaceutically-acceptable salts can be
prepared as alkaline metal or alkaline earth salts, such as sodium, potassium or calcium
salts.
The pharmaceutical compositions may be combined, if desired, with a pharmaceutically-
acceptable carrier. The term "pharmaceutically-acceptable carrier" as used herein
means one or more compatible solid or liquid fillers, diluents or encapsulating substances
that are suitable for administration into a human. The term "carrier" denotes an organic
or inorganic ingredient, natural or synthetic, with which the active ingredient is combined
to facilitate the application. The components of the pharmaceutical compositions also are
capable of being co-mingled with the molecules of the present invention, and with each
other, in a manner such that there is no interaction that would substantially impair the
desired pharmaceutical efficacy.
The pharmaceutical compositions may contain suitable buffering agents, including: acetic
acid in a salt; citric acid in a salt; boric acid in a salt; and phosphoric acid in a salt.
The pharmaceutical compositions also may contain, optionally, suitable preservatives,
such as: benzalkonium chloride; chlorobutanol; parabens and thimerosal.
The pharmaceutical compositions may conveniently be presented in unit dosage form
and may be prepared by any of the methods well-known in the art of pharmacy. All
methods include the step of bringing the active agent into association with a carrier that

constitutes one or more accessory ingredients. In general, the compositions are
prepared by uniformly and intimately bringing the active compound into association with a
liquid carrier, a finely divided solid carrier, or both, and then, if necessary, shaping the
product.
Compositions suitable for oral administration may be presented as discrete units, such as
capsules, tablets, lozenges, each containing a predetermined amount of the active
compound. Other compositions include suspensions in aqueous liquids or non-aqueous
liquids such as syrup, elixir or an emulsion.
Compositions suitable for parenteral administration conveniently comprise a sterile
aqueous or non-aqueous preparation that is preferably isotonic with the blood of the
recipient. This preparation may be formulated according to known methods using
suitable dispersing or wetting agents and suspending agents. The sterile injectable
preparation also may be a sterile injectable solution or suspension in a non-toxic
parenterally-acceptable diluent or solvent, for example, as a solution in 1, 3-butane diol.
Among the acceptable solvents that may be employed are water, Ringer's solution, and
isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally
employed as a solvent or suspending medium. For this purpose any bland fixed oil may
be employed including synthetic mono-or di-glycerides. In addition, fatty acids such as
oleic acid may be used in the preparation of injectables. Carrier formulation suitable for
oral, subcutaneous, intravenous, intramuscular, etc. administrations can be found in
Remington's Pharmaceutical Sciences, Mack Publishing Co., Easton, PA.
According to a further aspect of the invention there is provided a method to treat a
human subject suffering from a condition that would benefit from administration of a
leptin agonist comprising administering an effective amount of at least one polypeptide
according to the invention.
In a preferred method of the invention said condition is obesity.
In a further preferred method of the invention said condition is an obesity related
condition.
In a preferred method of the invention said obesity related condition is type II diabetes.
In a preferred method of the invention said obesity related condition is heart disease.

In an alternative preferred method of the invention said condition is immune suppression.
According to a further aspect of the invention there is provided a method to treat a
human subject suffering from a condition that would benefit from administration of a
leptin antagonist comprising administering an effective amount of at least one
polypeptide according to the invention.
In a preferred method of the invention said condition is anorexia.
In a further preferred method of the invention said condition is an autoimmune disease.
In a preferred method of the invention said autoimmune disease is selected from the
group consisting of: multiple sclerosis, type 1 diabetes, autoimmune thyroid disease,
autoimmune hepatitis, rheumatoid arthritis, autoimmune colitis, crohns disease, celiac
disease, autoimmune nephritis, autoimmune neuropathy (guillan Barre), encephalopathy
(Rasmussen), fibrosing alveolitis.
In a preferred method of the invention said polypeptide is administered intravenously.
In an alternative preferred method of the invention said polypeptide is administered
subcutaneously.
In a further preferred method of the invention said polypeptide is administered at two day
intervals; preferably said polypeptide is administered at weekly, 2 weekly or monthly
intervals.
According to a further aspect of the invention there is provided a monoclonal antibody
that binds the polypeptide or dimer according to the invention.
Preferably said monoclonal antibody is an antibody that binds the polypeptide or dimer
but does not specifically bind leptin or leptin receptor individually.
The monoclonal antibody binds a conformational antigen presented either by the
polypeptide of the invention or a dimer comprising the polypeptide of the invention.

In a further aspect of the invention there is provided a method for preparing a hybridoma
cell-line producing monoclonal antibodies according to the invention comprising the steps
of:
i) immunising an immunocompetent mammal with an immunogen
comprising at least one polypeptide according to the invention;
ii) fusing lymphocytes of the immunised immunocompetent mammal with
myeloma cells to form hybridoma cells;
iii) screening monoclonal antibodies produced by the hybridoma cells of step
(ii) for binding activity to the polypeptide of (i);
iv) culturing the hybridoma cells to proliferate and/or to secrete said
monoclonal antibody; and
v) recovering the monoclonal antibody from the culture supernatant.
Preferably, the said immunocompetent mammal is a mouse. Alternatively, said
immunocompetent mammal is a rat.
The production of monoclonal antibodies using hybridoma cells is well-known in the art.
The methods used to produce monoclonal antibodies are disclosed by Kohler and
Milstein in Nature 256, 495-497 (1975) and also by Donillard and Hoffman, "Basic Facts
about Hybridomas" in Compendium of lmmunology V.Il ed. by Schwartz, 1981, which are
incorporated by reference.
According to a further aspect of the invention there is provided a hybridoma cell-line
obtained or obtainable by the method according to the invention.
Throughout the description and claims of this specification, the words "comprise" and
"contain" and variations of the words, for example "comprising" and "comprises", means
"including but not limited to", and is not intended to (and does not) exclude other
moieties, additives, components, integers or steps.
Throughout the description and claims of this specification, the singular encompasses the
plural unless the context otherwise requires. In particular, where the indefinite article is
used, the specification is to be understood as contemplating plurality as well as
singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in
conjunction with a particular aspect, embodiment or example of the invention are to be
understood to be applicable to any other aspect, embodiment or example described
herein unless incompatible therewith.
An embodiment of the invention will now be described by example only and with
reference to the following figures:
Table 1 LR fusion nomenclature;
Table 2 Expression levels of the leptin LR-fusions as determined by ELISA using
antibodies against the leptin receptor, (nd = not detectable)
Figure 1a is the nucleic acid sequence of bacterial expressed leptin; Figure 1b is the
amino acid sequence;
Figure 2a is the nucleic acid sequence of LR 2A1; Figure 2b is the amino acid sequence
of LR 2A1;
Figure 3a is the nucleic acid sequence of LR 2A1; Figure 2b is the amino acid sequence
of LR 2A1 adapted for bacterial expression;
Figure 4a is the nucleic acid sequence of LR 2B1; Figure 2b is the amino acid sequence
of LR 2B1;
Figure 5a is the nucleic acid sequence of LR 2D1; Figure 2b is the amino acid sequence
of LR 2D1;
Figure 6a is the nucleic acid sequence of LR 2E1; Figure 2b is the amino acid sequence
of LR 2E1;
Figure 7a is the nucleic acid sequence of LR 2F1; Figure 2b is the amino acid sequence
of LR 2F1;

Figure 8a is the nucleic acid sequence of LR 2G1; Figure 2b is the amino acid sequence
of LR 2G1;
Figure 9a is the nucleic acid sequence of LR 2H1; Figure 2b is the amino acid sequence
of LR 2H1;
Figure 10a is the nucleic acid sequence of LR 211; Figure 2b is the amino acid sequence
of LR 2M;
Figure 11a is the nucleic acid sequence of LR 2J1; Figure 2b is the amino acid sequence
of LR 2J1;
Figure 12a is the nucleic acid sequence of LR 2K1; Figure 2b is the amino acid sequence
of LR 2K1;
Figure 13a is the nucleic acid sequence of LR 2L1; Figure 2b is the amino acid sequence
of LR 2L1;
Figure 14 is the nucleic acid sequence of LR 2M1; Figure 2b is the amino acid sequence
of LR 2M1;
Figure 15 a) The leptin binding domain (LBD) is ligated into the expression vector
pSecTag to generate pSecTaglinkSSLBD. b) leptin is ligated into pSecTaglinkSSLBD to
generate pSecTag2A1(lm). c) DNA is synthesised and ligated into pSecTag2A1 (Im) to
introduce a (G4S)5;
Figure 16 Western blot of media from CHO cells expressing leptin LR-fusion. The
contents of the lanes are 1 2A1 expression; 2.2B1 expression; 3 2D1 expression; 4.
Markers (20, 25, 37, 50, 75, 100, 150, 200 kDa). The western blot was probed with
antibodies against leptin.
Figure 17 a) The leptin receptor extracellular domains (ObRex) are ligated into the
expression vector pSecTag to generate pSecTaglinkSSObRex. b) leptin is ligated into
pSecTaglinkSSObRex to generate pSecTag2B1(lm). c) DNA is synthesised and ligated
into pSecTag2B1(lm) to introduce a (G4S)5;

Figure 18 a) PCR was used to generate DNA consisting of the gene of interest flanked
by suitable restriction sites (contained within primers R1-4). b) The PCR products were
ligated into a suitable vector either side of the linker region, c) The construct was then
modified to introduce the correct linker, which did not contain any unwanted sequence
(i.e. the non-native restriction sites);
Figure 19 a) Oligonucleotides were designed to form partially double-stranded regions
with unique overlaps and, when annealed and processed would encode the linker with
flanking regions which would anneal to the ligand and receptor, b) PCRs were performed
using the "megaprimer" and terminal primers (R1 and R2) to produce the LR-fusion gene.
The R1 and R2 primers were designed so as to introduce useful flanking restriction sites
for ligation into the target vector;
Figure 20 is the amino acid sequence of full length leptin receptor;
Figure 21 is a schematic diagram of the leptin LR-fusion constructs;
Figure 22 is an Immuno-blot analysis of CHO Flp-ln stable cell lines expressing 2A1, 2B1
and 2D1 constructs. Lane M = Markers (at 250, 150, 100, 75, 50, 37, 25 and 20kDa);
Lane 1= CHO Flp-ln control cells, Lane 2 = 2A1 expression media, Lane 3 = 2B1
expression media, Lane 4 = 2D1 expression media;
Figure 23 is expression of 2A1Ecopt. A) Coomassie stained gels showing 2A1Ecopt
expression. Lane M = Markers (at 250, 150, 100, 75, 50, 37, 25, 20 and 15kDa); Lane 1
= Expression at induction; Lane 2 = Expression 4 hours post-induction; Lane 3 =
Expression after overnight incubation, post-induction; Lane 4 = insoluble fraction of
2A1Ecopt expressing cells; Lane 5 = soluble fraction of 2A1Ecopt expressing cells. B)
Immuno-blot of 2A1Ecopt expression. Lane M = Markers (at 250, 150, 100, 75, 50, 37,
25, 20 and 15kDa); Lane 1 = Expression at induction; Lane 2 = Expression 4 hours post-
induction; Lane 3 = Expression after overnight incubation, post-induction;
Figure 24 is a Coomassie stained SDS-PAGE gel of the inclusion body prep for
2A1Ecopt. Lane M = Markers (at 250, 150, 100, 75, 50, 37, 25 and 20kDa); Lane 1= E
coli BL21(DE3):2A1Ecopt whole cell; Lane 2 = Cell lysate - soluble fraction; Lane 3 = cell

t
lysate - insoluble fraction; Lanes 4-7 = 2% sodium deoxychlate washes 1-4; Lanes 8-9 =
water washes 1-2; Lane 10 = Inclusion body prep.
Figure 25 is an In vitro bioassay of crude media from CHO Flp-ln cells expressing 2A1.
Crude media (10x concentrate) from CHO Flp-ln cells expressing 2A1 was used to
stimulate the cells in the leptin in vitro bioassay. The media gave agonistic activity, media
from cells not expressing 2A1 gave no activity (black columns); and
Figure 26 is an In vitro bioassay of the purified 2A1Ecopt. Refolded 2A1Ecopt samples
which showed a single band at the correct size for 2A1 Ecopt in the immuno-blots were
used to stimulate the cells in the leptin in vitro bioassay. The samples showed agonistic
activity.
Materials and Methods
In vitro testing
In vitro methods to detect and assess the activity of leptin are known in the art. For
example see Liu et al (Endocrinology (1997) 138, 8: p3548-3554); White et al (J. Biol
Chemistry (1997) 272(7): p4065-4071); and Maamra et al (Endocrinology (2007) 142(10):
4389-4393) which each describe, inter alia, the expression of leptin receptor in a cell
based assay.
In addition Leptin LR-fusions were tested for in vitro activity using a dual-luciferase
bioassay. Briefly, MCF-7 mammalian cells were transfected with plasmids expressing
firefly luciferase induced by SIE, leptin receptor (ObR), STAT3 and Renilla luciferase (the
latter three proteins are constitutively expressed). Twenty-four hours later the cells are
stimulated for six hours with the leptin LR-fusion. The cells were lysed and the Firefly
luciferase activity measured, this is proportional to the stimulation of the leptin receptor
by the LR-fusion. Dividing this value by the activity of the constitutively expressed Renilla
luciferase gives an activity corrected for experimental error.
In vivo testing

In vivo animal models are known in the art. The ob/ob mouse model (Zhang et al Nature
(1994) 372: 425-432) is homozygous for a leptin mutation and has been used to assess
the activity of leptin agonists and antagonist; see Chehab et al (Nature Genetics (1996)
12: 318-320); Lord et al (Nature (1998) 394: 897-901); and Pellymounter et al (Science
(1995)269:540-542).
Immunological testing
Immunoassays that measure the binding of ligand or receptor to polyclonal and
monoclonal antibodies are known in the art. Commercially available antibodies are
available to detect the ligand or receptor in samples and also for use in competitive
inhibition studies. For example, see http://www.abcam.com/index.html, Abcam PLC.
Recombinant Production of fusion proteins
The components of the fusion proteins were generated by PCR using primers designed
to anneal to the ligand or receptor and to introduce suitable restriction sites for cloning
into the target vector (Fig X1a). The template for the PCR comprised the target gene and
was obtained from IMAGE clones, cDNA libraries or from custom synthesised genes.
Once the ligand and receptor genes with the appropriate flanking restriction sites had
been synthesised, these were then ligated either side of the linker region in the target
vector (Fig X1b). The construct was then modified to contain the correct linker without
flanking restriction sites by the insertion of a custom synthesised length of DNA between
two unique restriction sites either side of the linker region, by mutation of the linker region
by ssDNA modification techniques, by insertion of a primer duplex/multiplex between
suitable restriction sites or by PCR modification (FigXIc).
Alternatively, the linker with flanking sequence, designed to anneal to the ligand or
receptor domains of choice, was initially synthesised by creating an oligonucleotide
duplex and this processed to generate double-stranded DNA (Fig X2a). PCRs were then
performed using the linker sequence as a "megaprimer", primers designed against the
opposite ends of the ligand and receptor to which the "megaprimer" anneals to and with

the ligand and receptor as the templates. The terminal primers were designed with
suitable restriction sites for ligation into the expression vector of choice (Fig X2b).
Expression and Purification of Fusion Proteins
Expression was carried out in a suitable system (e.g. mammalian CHO cells, E. coli, etc.)
and this was dependant on the vector into which the LR-fusion gene was generated.
Expression was then analysed using a variety of methods which could include one or
more of SDS-PAGE, Native PAGE, western blotting, ELISA.
Once a suitable level of expression was achieved the RL-fusions were expressed at a
larger scale to produce enough protein for purification and subsequent analysis.
Purification was carried out using a suitable combination of one or more chromatographic
procedures such as ion exchange chromatography, hydrophobic interaction
chromatography, ammonium sulphate precipitation, gel filtration, size exclusion and/or
affinity chromatography (using nickel/cobalt-resin, antibody-immobilised resin and/or
ligand/receptor-immobilised resin).
Purified protein was analysed using a variety of methods which could include one or
more of Bradford's assay, SDS-PAGE, Native PAGE, western blotting, ELISA.
Characterisation of LR-fusions
Denaturing PAGE, native PAGE gels and western blotting were used to analyse the
fusion polypeptides and western blotting performed with antibodies non-conformationally
sensitive to the LR-fusion. Native solution state molecular weight information can be
obtained from techniques such as size exclusion chrmoatography using a Superose
G200 analytical column and analytical ultracentrifugation.
Construction of LR-fusions
The 2A1, 2B1 and 2D1 genes were synthesised by generating the Ob, LBD, ObREc and
linker components with unique, compatible restriction sites at either end and ligating them
together to form the complete gene. Extraneous sequence (i.e. the restriction sites) in

2B1 and 2D1 were subsequently removed by ligating in custom synthesised DNA
fragments (Genecust, France) between unique restriction sites within the Ob, LBD and
ObREc genes, this generated 2B2 and 2D2. The 2A1Ecopt gene was generated by
custom DNA synthesis (Genecust, France) and ligated into pET21a+. The 2A1Ecopt
sequence is codon optimised for expression in E. coli and has a C-terminal His tag.
Expression of LR-fusions
Mammalian expression:
Stable cell lines were generated using a modified Invitrogen vector pSecTag-V5/FRT-Hist
in 6-well plates using Fugene-6 as the transfection reagent. The CHO Flp-ln cells were
co-transfected with the expression vector and pOG44, a plasmid that expresses flp
recombinase an enzyme which causes the recombination of the LR-fusion gene into a
"hot-spot" of the cell chromosome. Hygromycin B was used to select for cells with
positive recombinants.
Once the stable cell lines had been established they were grown on 75cm2 culture plates,
at a confluency of 50-70% the media was changed to serum free media. The cultures
were incubated for a further 2-4 days after which media samples were taken. These were
run on 13% SDS-PAGE gels and transferred to PVDF membrane for immuno- blotting.
After blocking in 5% (w/v) milk protein in PBS + 0.05% (v/v) Tween 20, sample detection
was carried out using a specific anti-leptin antibody together with a Horse Radish
Peroxidase (HRP) conjugated secondary antibody. Visualisation was by
chemiluminesence on photographic film using an HRP detection kit.
The immuno-blots showing the expression of the LR-fusions from the mammalian system
are shown in Figure 22.
E. coli expression:
pET21a+:2A1Ecopt was transformed into chemically competent E. coli BL21(DE3) cells.
Clones expressing 2A1Ecopt were then grown in LB media supplemented with
carbenicillin (100ug/ml) and grown on a flat bed shaker at room temperature. Induction
was performed with 1mM IPTG at an OD600 of 0.4 and the culture grown for overnight.
The cells were then harvested and lysed, samples were then run on SDS-PAGE gels and
coomassie stained or immuno-blotted.

The immuno-blots showing the expression of the LR-fusions from the E.coli system are
shown in Figure 23.
Purification of LR-fusions
E. co//expressed LR-fusion purification (2A1Ecopt)
2A1Ecopt was expressed in E. coli BL21(DE3) cells from the plasmid
pET21a+:2A1Ecopt.
2A1Ecopt was purified using a Ni-Probond resin column. The insoluble fraction of the
lysed cells was washed four times with 2% sodium deoxycholate and the two times with
distilled water to give an inclusion body prep. This step removed most of the
contaminating proteins giving >80% purity for 2A1 Ecopt; Figure 24.
Statistics
Two groups were compared with a Student's test if their variance was normally
distributed or by a Student-Satterthwaite's test if not normally distributed. Distribution was
tested with an F test. One-way ANOVA was used to compare the means of 3 or more
groups and if the level of significance was p<0.05 individual comparisons were performed
with Dunnett's tests. All statistical tests were two-sided at the 5% level of significance and
no imputation was made for missing values.
Example 1: 2A1
DNA encoding the leptin binding domain (LBD) domains of the leptin receptor (ObR)
flanked by BamHI and Hindlll was produced by PCR. This was then ligated into a
modified pSecTag-FRT-V5-His TOPO vector to produce pSecTagLinkSSLBD (Fig 15a).
DNA encoding leptin flanked by Nhel and BamHI was produced by PCR using the
primers; NheObssF (5'-gggaaagctagccaccatgcattggggaaccctgtgcg-3') and
ObBamR (5'-gggaaaggatccgcacccagggctgaggtcc-3'). This was ligated into
pSecTagLinkSSLBD to produce pSecTag2A1(lm) (Fig 15b). The linker region was

custom synthesised between Alel and Nsil restriction sites and this inserted into
pSecTag2A1 (Im) to give pSecTag2A1stop (Fig 15c). pSecTag2A1stop was transfected
into Chinese Hamster Ovary (CHO) cells and transient and stable expression cell lines
developed. However western blot of the expression media, using antibodies against
leptin, showed 2A1 was expressed (Fig 16). 2A1 was also expressed in Escherichia coli
cells. The amino acid sequence for 2A1 was back-translated with optimisation for E. coli
codon usage. The codon optimised gene (2A1Ecopt) was custom gene synthesised and
then inserted into the pET21a+ expression vector and the protein expressed from E. coli
BL21 (DE3) cells.
Example 2: 2B1
DNA encoding the leptin receptor extracellular domain (ObRex) flanked by BamHI and
Hindi 11 was produced by PCR. This was then ligated into a modified pSecTag-FRT-V5-
His TOPO vector to produce pSecTagLinkSSObRex (Fig 17a). DNA encoding leptin
flanked by Nhel and BamHI was produced by PCR using the primers; NheObssF (5'-
gggaaagctagccaccatgcattggggaaccctgtgcg-3') and ObBamR (5'-
gggaaaggatccgcacccagggctgaggtcc-3'). This was ligated into
pSecTagLinkSSObRex to produce pSecTag2B1(lm) (Fig 17b). The linker region was
custom synthesised between Alel and BstBI restriction sites and this inserted into
pSecTag2B1(lm) to give pSecTag2B1stop (Fig 17c). pSecTag2B1stop was transfected
into Chinese Hamster Ovary (CHO) cells and transient and stable expression cell lines
developed. Expression levels were determined to be in the low ng/ml levels as measured
by ELISA using antibodies against ObR (Table 2). However these expression levels may
have been underestimated by the ELISA since the western blot of the expression media
suggests that higher levels of expression have been achieved (Fig 16).
Example 3: 2D1
pSecTag2D1stop was synthesised in a similar way to pSecTag2B1stop, above.
pSecTag2B1stop was transfected into Chinese Hamster Ovary (CHO) cells and transient
and stable expression cell lines developed. Expression levels were determined to be in
the low ng/ml levels as measured by ELISA using antibodies against ObR (Table 2).
However these expression levels may have been underestimated by the ELISA since the

western blot of the expression media suggests that higher levels of expression have been
achieved (Fig 16).
Example 4 In vitro bioassay results
The in vitro bioassay utilises a dual-luciferase reporter system to measure the activity of
stimulated MCF-7 cells.
MCF-7 cells were transfected with plasmid expressing ObR, STAT5, SIE and Renilla
luciferase. Activation of the ObR caused an inducible, proportional expression of firefly
luciferase via STAT3 and SIE; the Renilla luciferase was constitutively expressed and
acted as a control to normalise the firefly luciferase activity measurement. Both the firefly
and Renilla luciferase were measured using the Dual-Luciferase Reporter Assay System
(Promega) and a luminometer. Dividing the firefly luciferase measurement by the Renilla
luciferase measurement gave a corrected activity (i.e. correction for differences between
samples such as cell density and transfection efficiency). The corrected activity was then
divided by the activity of un-stimulated cells to give a "fold induction" value.
The bioactivity for 2A1 (10x concentrate) and 2A1Ecopt (purified) is shown in Figures 25
and 26 respectively.

WE CLAIM :
1 A nucleic acid molecule comprising a nucleic acid sequence that encodes a
polypeptide that has the activity of leptin comprising a leptin polypeptide linked, directly or
indirectly, to at least one leptin binding domain of the leptin receptor polypeptide.
2. A fusion polypeptide comprising: the amino acid sequence of the leptin
polypeptide, or active part thereof linked, directly or indirectly, to at least one leptin
binding domain of the leptin receptor polypeptide.
3. A fusion polypeptide according to claim 2 wherein said polypeptide comprises two
leptin binding domains.
4. A fusion polypeptide according to claim 2 or 3 wherein said fusion polypeptide
comprises an immunoglobulin-like domain.
5. A fusion polypeptide according to any of claims 2-4 wherein said polypeptide
comprises at least one cytokine-like homology domain.
6. A fusion polypeptide according to any of claims 2-4 wherein said polypeptide
comprises two cytokine-like homology domains.
7. A fusion polypeptide according to any of claims 2-6 wherein said polypeptide
comprises at least one fibronectin III binding domain.
8. A fusion polypeptide according to any of claims 2-6 wherein said polypeptide
comprises two fibronectin III binding domains.
9. A fusion polypeptide according to any of claims 2-8 wherein said polypeptide
comprises amino acid residues 425-535 of SEQ ID NO: 41.
10. A fusion polypeptide according to any of claims 2-9 wherein said polypeptide
comprises amino acid residues 536-635 of SEQ ID NO: 41.

11. A fusion polypeptide according to any of claims 2-10 wherein said polypeptide
comprises amino acid residues 326-427 of SEQ ID NO: 41.
12. A fusion polypeptide according to any of claims 2-11 wherein said polypeptide
comprises amino acid residues 62-178 of SEQ ID NO: 41.
13. A fusion polypeptide according to any of claims 2-12 wherein said polypeptide
comprises amino acid residues 235-325 of SEQ ID NO: 41.
14. A fusion polypeptide according to any of claims 2-13 wherein said polypeptide
comprises amino acid residues 636-733 of SEQ ID NO: 41.
15. A fusion polypeptide according to any of claims 2-14 wherein said polypeptide
amino acid residues 734-829 of SEQ ID NO: 41.
16. A fusion polypeptide according to any of claims 2-15 wherein said polypeptide
comprises amino acid residues 428-635 of SEQ ID NO: 41.
17. A fusion polypeptide according to any of claims 2-16 wherein said leptin
polypeptide is linked to at least one leptin binding domain of leptin receptor wherein said
leptin polypeptide is positioned amino-terminal to said leptin binding domain in said fusion
polypeptide.
18. A fusion polypeptide according to any of claims 2-16 wherein said leptin
polypeptide is linked to at least one leptin binding domain of leptin receptor wherein said
leptin polypeptide is positioned carboxyl-terminal to said leptin binding domain in said
fusion polypeptide.
19. A fusion polypeptide according to any of claims 2-18 wherein said leptin
polypeptide is linked to at least one binding domain of the leptin receptor polypeptide by a
peptide linker.
20. A fusion polypeptide according to claim 19 wherein said peptide linking molecule
comprises at least one copy of the peptide Gly Gly Gly Gly Ser.

21. A fusion polypeptide according to claim 20 wherein said peptide linking molecule
comprises 2, 3, 4, 5, 6, 7, 8, 9 or 10 copies of the peptide Gly Gly Gly Gly Ser.
22. A fusion polypeptide according to claim 21 wherein said peptide linking molecule
consists of 6 copies of the peptide Gly Gly Gly Gly Ser.
23. A fusion polypeptide according to claim 21 wherein said peptide linking molecule
consists of 8 copies of the peptide Gly Gly Gly Gly Ser.
24. A fusion polypeptide according to any of claims 2-18 wherein said fusion
polypeptide is a direct fusion of leptin polypeptide and at least one leptin binding domain
of the leptin receptor polypeptide.
25. A nucleic acid molecule comprising a nucleic acid sequence selected from:
i) a nucleic acid sequence as represented in SEQ ID NO:3 ;
ii) a nucleic acid sequence as represented in SEQ ID NO:5;
iii) a nucleic acid sequence as represented in SEQ ID NO:7;
iv) a nucleic acid sequence as represented in SEQ ID NO:9;
v) a nucleic acid sequence as represented in SEQ ID NO:11;
vi) a nucleic acid sequence as represented in SEQ ID NO: 13;
vii) a nucleic acid sequence as represented in SEQ ID NO: 15;
viii) a nucleic acid sequence as represented in SEQ ID NO: 17;
ix) a nucleic acid sequence as represented in SEQ ID NO: 19;
x) a nucleic acid sequence as represented in SEQ ID NO:21;
xi) a nucleic acid sequence as represented in SEQ ID NO:23;
xii) a nucleic acid sequence as represented in SEQ ID NO:25;
xiii) a nucleic acid sequence as represented in SEQ ID NO:27;
a nucleic acid molecule comprising a nucleic sequence that hybridizes under stringent
hybridization conditions to SEQ ID NO: 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25 or 27 and
which encodes a polypeptide that has leptin receptor modulating activity.
26. A nucleic acid molecule according to claim 25 wherein said nucleic acid molecule
encodes a leptin agonist.

27. A nucleic acid molecule according to claim 25 wherein said nucleic acid molecule
encodes a leptin antagonist.
28 A nucleic acid molecule according to any of claims 25-27 wherein said nucleic
acid molecule comprises a nucleic acid sequence as represented in SEQ ID NO: 3.
29. A nucleic acid molecule according to any of claims 25-27 wherein said nucleic
acid molecule comprises a nucleic acid sequence as represented in SEQ ID NO: 5.
30. A nucleic acid molecule according to any of claims 25-27 wherein said nucleic
acid molecule comprises a nucleic acid sequence as represented in SEQ ID NO: 7.
31. A nucleic acid molecule according to any of claims 25-27 wherein said nucleic
acid molecule comprises a nucleic acid sequence as represented in SEQ ID NO: 9.
32. A nucleic acid molecule according to any of claims 25-27 wherein said nucleic
acid molecule comprises a nucleic acid sequence as represented in SEQ ID NO: 11.
33. A nucleic acid molecule according to any of claims 25-27 wherein said nucleic
acid molecule comprises a nucleic acid sequence as represented in SEQ ID NO: 13.
34. A nucleic acid molecule according to any of claims 25-27 wherein said nucleic
acid molecule comprises a nucleic acid sequence as represented in SEQ ID NO: 15.
35. A nucleic acid molecule according to any of claims 25-27 wherein said nucleic
acid molecule comprises a nucleic acid sequence as represented in SEQ ID NO: 17.
36. A nucleic acid molecule according to any of claims 25-27 wherein said nucleic
acid molecule comprises a nucleic acid sequence as represented in SEQ ID NO: 19.
37. A nucleic acid molecule according to any of claims 25-27 wherein said nucleic
acid molecule comprises a nucleic acid sequence as represented in SEQ ID NO: 21.
38. A nucleic acid molecule according to any of claims 25-27 wherein said nucleic
acid molecule comprises a nucleic acid sequence as represented in SEQ ID NO: 23.

39. A nucleic acid molecule according to any of claims 25-27 wherein said nucleic
acid molecule comprises a nucleic acid sequence as represented in SEQ ID NO: 25.
40. A nucleic acid molecule according to any of claims 25-27 wherein said nucleic
acid molecule comprises a nucleic acid sequence as represented in SEQ ID NO: 27.
41. A polypeptide encoded by the nucleic acid molecule according to any of claims 1
or 25-40.
42. A polypeptide comprising an amino acid sequence as represented in SEQ ID NO:
4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or
40.
43. A homodimer consisting of two polypeptides wherein each of said polypeptides
comprises:
i) a first part comprising leptin, or a receptor binding domain thereof,
optionally linked by a peptide linking molecule to
ii) a second part comprising at least one leptin binding domain or part
thereof, of the leptin receptor.
44. A homodimer according to claim 43 wherein said homodimer comprises two
polypeptides comprising SEQ ID NO: of SEQ ID NO: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22,
24, 26, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40..
45. A vector comprising a nucleic acid molecule according to any of claims 1 or 25-
40.
46. A cell transfected or transformed with a nucleic acid molecule or vector according
to any of claims 1, 25-40 or 45.
47. A cell according to claim 46 wherein said cell is a eukaryotic cell.
48. A cell according to claim 46 wherein said cell is a prokaryotic cell.

49. A pharmaceutical composition comprising a polypeptide according to any of
claims 2-24 or 41 or 42 including an excipient or carrier.
50. A pharmaceutical composition according to claim 49 wherein composition is
combined with a further therapeutic agent.

This disclosure relates to leptin fusion polypeptides; nucleic acid molecules encoding said
polypeptides and methods of treatment that use said polypeptides.