1. XTEN Concept
O O O
O O O O PEG
O O O
N
N
N
N
N
N
Polypeptide Backbone = XTEN
N
O O O
Composed of natural amino acids
• Biodegradable
• No risk of kidney vacuolation
• No toxic metabolites
Encoded by DNA
• Precisely-controlled sequence and length
• Option to introduce conjugation sites
• Large-scale production via fermentation
XTEN is a protein that mimics the polymer properties of PEG
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2. Versatility of XTEN
Genetic Fusion Chemical Conjugation
XTEN
XTEN Drug
Drug XTEN
XTEN
Expression Plasmid Expression Plasmid
ORI Select
ion ORI Select
ion
Payloads: Payloads:
• Proteins • Proteins
• Peptides • Peptides
• Peptidomimetics
• Organic molecules
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3. XTEN Design and Properties
Goals
•Long Serum Half-life
•Stable in Plasma Composition A, G, E, P, S, T
•Degraded Intracellularly Size 864 AA = 75 kDa
•High Expression Level
•Genetically Stable Expression E. coli & Mammalian
•No Non-specific Binding SDS-PAGE, SEC, MS Homogeneous
•No Aggregation
•Non-Immunogenic Solubility >117 mg/mL
Viscosity Similar to PEG
Plasma Stability >30 days
Solution
•No unstable AA Biodegradable Yes
•No hydrophobic AA Endotoxin/DNA/HCP All easily removed
•Multiple AA types
•Not Repetitive
Current XTEN meets all goals and requirements
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4. XTEN Technology
Protein-Based Polymer Monodisperse by ESI-MS
…GSTSESPSGTAPGTSPSGESSTAP
GSTSESPSGTAPGSTSESPSGTAPGT
STPESGSASPGTSTPESGSASPGST
SESPSGTAPGSTSESPSGTAPGTSPS
GESSTAPGSTSESPSGTAPGTSPSG
ESSTAPGTSPSGESSTAPGSTSSTAE
SPGPGTSPSGESSTAPGTSPSGESS
TAPGSTSE…
Unstructured by CD Large Hydrodynamic Radius by SEC
XTEN
Schellenberger et al., (2009) Nature Biotechnology, 27, 1186-90
XTEN is a protein polymer with properties similar to those of PEG
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5. Homogeneity by ESI Mass Spec
XTEN PEG
GLP2-XTEN880 G-CSF-PEG20 (Neulasta)
Calc. 84,830 Da
Exp. 84,831 Da
38000 39000 40000 41000 42000 43000
Mass (Da) Mass (Da)
Bagal D., et al. (2008) Anal. Chem., 80: 2408-18
1 Species >100 Species
XTEN is homogeneous whereas PEG is highly heterogeneous
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6. XTEN Properties
Property Details
Composed of natural amino acids • Biodegradable
• Non-toxic metabolites
Encoded by DNA • Precisely-controlled sequence and length
• Option to introduce conjugation sites
• Large scale production via fermentation
Extremely hydrophilic • Long in vivo half-life
Large hydrodynamic radius • Non-immunogenic
• Option to solubilize hydrophobic payloads
Chemically defined structure • Purification by RP-HPLC
• Characterization by Mass Spectrometry
Strong IP protection • Broad portfolio of patents and applications
Flexible product format • Controlled valency
• Bispecific products
• Drug conjugates
XTEN offers a superior combination of properties
compared to other half-life technologies
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7. Comparison of XTEN vs. PEG
Property XTEN PEG
Large Hydrodynamic Radius Yes Yes
In vivo Half-Life Very Long Very Long
Immunogenicity Extremely Low Extremely Low
Manufacturing Process Recombinant Chemical
Conjugation Chemistries Many Many
Solubility Very High Very High
PK Assays Available Available
Biodegradable = Safety Benefit Yes No
Uniform Polymer Length Yes No
Peptide Mapping Yes No
Chemical Structure Confirmation by MS Yes No
RP-HPLC Peak Resolution High Low
Capture by Ion Exchange Yes No
Number & Position of Functional Groups Fully Flexible Few Choices
Patent Life Extension Yes Limited
XTEN offers multiple advantages over PEG
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8. Benefits of Long In Vivo Half-Life
Simulated PK Curves
Free Drug XTENylated Drug
Plasma Concentration
Toxicity
Free XTENylated
Parameter
Drug Drug
Therapeutic T1/2 (hrs) 2 168
Window
Distribution T1/2 (hrs) 2 30
Dose Interval (hrs) 12 Single dose
No Efficacy
Time
• Prevent spikes in plasma concentration  reduced toxicity
• Prevent periods of low plasma concentration  increased efficacy
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9. XTEN Preclinical PK data data
XTEN Preclinical PK
-XTEN +XTEN
Payload Product Species Fold Increase
T1/2 (hr) T1/2 (hr)
Exenatide VRS-859 Monkey 0.48 60 125
hGH VRS-317 Monkey 1.6 110 69
AAT Monkey 1 120 120
GLP2-2G Rat 0.5 44 88
GLP2-2G Mouse 0.4 34 85
XTEN greatly extends the serum half-life of proteins and peptides
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10. Pharmacokinetics - Example
PK of GLP2-2G-XTEN in Cynomolgus Macaques
• T1/2 = 120 hours,
• Bioavailability = 96%
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11. XTEN Publications
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12. Safety
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13. XTEN Immunogenicity Summary
• Zero hydrophobic residues
• Zero epitopes by Tepitope prediction
• Zero epitopes by Epivax prediction
• Morphosys panned 4 times – no binders
• Non-immunogenic in in-house animal studies
• Mice, rats, rabbit, cyno: 439 epitopes; 67 animals; <10 sc injections
• Non-immunogenic in 2 toxicology studies
• Mice: 14 SC injections; Monkeys: 5 SC injections
• Monkeys: 7 SC injections
• Non-immunogenic in 2 clinical trials (120 patients)
• 1 monthly dose, but Exenatide payload shows response after 10 days
• Non-immunogenic even with Freund’s adjuvant
• 20 mice, 6 rabbits: antibody titer too low to be useful
• All data suggest that XTEN is non-immunogenic in animals
• XTEN is as foreign to animals as to humans
• XTEN is therefore expected to be non-immunogenic in humans
• Initial clinical results support this conclusion
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14. Biodegradation
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15. Kidney Vacuolation: PEG versus XTEN
PEG XTEN
• Stable in serum • Stable in serum
• Not bio-degradable • Degraded by intracellular proteases
• Accumulates in kidney cells • No accumulation in kidney cells
• Forms vacuoles • No vacuolation
“The non-biodegradable nature of PEG may become a limiting factor for the next generation of
protein pharmaceuticals” Gaberc-Porekar, V., et al. (2008) Curr Opin Drug Discov Devel, 11: 242
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16. Biodegradation of XTEN versus PEG
Monkey Plasma Monkey, In vivo Kidney Homogenate
Time (days) Time (days) Time (days)
0 1 7 0 1 7 0 1 7
Incubated at 37C in Injected into cynomolgus Incubated at 37C in rat
50% plasma monkey and recovered by IP kidney homogenate
XTEN is stable in blood but degraded by intracellular proteases
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