Fusion proteins comprising sulfoglucosamine sulfohydrolase enzymes and methods thereof
Inventors
Giese, Tina • Kannan, Gunasekaran • Kariolis, Mihalis S. • Mahon, Cathal S.
Assignees
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Publication Number
US-11884944-B2
Publication Date
2024-01-30
Expiration Date
Abstract
Provided herein are proteins, which are capable of being transported across the blood-brain barrier (BBB) and comprise sulfoglucosamine sulfohydrolase (SGSH) enzyme-Fc fusion polypeptides. Certain embodiments also provide methods of using such proteins to treat Sanfilippo syndrome A.
Core Innovation
The disclosed invention relates to enzyme replacement therapy for Sanfilippo syndrome A (MPS IIIA) using an ETV:SGSH (SGSH-Fc) approach. The therapy comprises a protein having SGSH activity delivered as a fusion construct intended to act in the central nervous system while reducing toxic metabolite accumulation associated with Sanfilippo syndrome A.
The core protein architecture is a protein comprising a first fusion polypeptide and a second fusion polypeptide. Each fusion polypeptide includes an Fc polypeptide linked to an N-sulfoglucosamine sulfohydrolase (SGSH) amino acid sequence, using specified SGSH sequence options for the first fusion polypeptide and the second fusion polypeptide.
The described design includes Fc modifications configured for transferrin receptor (TfR) binding to cross the blood-brain barrier (BBB). The disclosure characterizes Fc mutation sets, including knob/hole heterodimerization and TfR-binding substitutions, and evaluates retention of SGSH in vitro and in cells together with brain uptake and downstream reduction of heparan sulfate (HS)-derived substrates in brain and in CSF after intravenous dosing.
A TfR-binding SGSH-Fc fusion protein (ETV:SGSH; Bizyme Structure 1) increases brain SGSH-Fc exposure versus a control SGSH-Fc lacking TfR-binding mutations after intravenous dosing. In an MPS III (Sgshmps3a×TfRmu/hu) KI model, a single ETV:SGSH dose reduces heparan-sulfate (HS) in brain and CSF, and an Fc variant with P329S retains comparable brain HS reduction while differing in critical post-translational processing and purification outcomes.
Claims Coverage
The independent claim coverage includes a defined dual fusion protein architecture using two Fc-linked SGSH fusion polypeptides with specific allowable SEQ ID selections, together with additional constraints that exclude immunoglobulin variable regions and antigen-binding portion. Dependent claims further refine the scope with particular SEQ ID combinations and, in at least one dependent claim, a quantitative brain uptake constraint tied to TfR-binding modifications of the second Fc polypeptide.
Two Fc-linked SGSH fusion polypeptides with defined SGSH sequence options
A protein comprising a first fusion polypeptide comprising a first Fc polypeptide linked to a first N-sulfoglucosamine sulfohydrolase (SGSH) amino acid sequence, wherein the first fusion polypeptide comprises any one of SEQ ID NOs: 65-68, and a second fusion polypeptide comprising a second Fc polypeptide linked to a second SGSH amino acid sequence, wherein the second fusion polypeptide comprises any one of SEQ ID NOs: 93-96.
Increased brain uptake with TfR-binding on the second Fc
The uptake of the SGSH amino acid sequence into the brain is at least four-fold greater than uptake of the SGSH enzyme lacking modifications to the second Fc polypeptide that confer TfR binding.
Exclusion of immunoglobulin variable regions and antigen-binding portions
The protein is characterized by lacking an immunoglobulin heavy and/or light chain variable region sequence and lacking an antigen-binding portion thereof.
Specific fusion polypeptide sequence identities for first and second fusions
The protein is defined such that its first fusion polypeptide contains SEQ ID NO:67 or 68 and its second fusion polypeptide contains SEQ ID NO:95 or 96.
Specific second fusion polypeptide sequence identity
The protein includes a second fusion polypeptide defined by SEQ ID NO:93.
Overall, claim coverage focuses on a two-part SGSH-Fc fusion protein with defined SGSH sequence options, together with dependent-claim refinements specifying particular SEQ ID NO selections, brain uptake, and structural omission constraints.
Stated Advantages
Increased uptake of the SGSH amino acid sequence into the brain, stated as at least four-fold greater than a SGSH enzyme lacking TfR-binding modifications on the second Fc.
Increased brain SGSH-Fc exposure versus a control SGSH-Fc lacking TfR-binding mutations.
Reduced accumulation of toxic metabolites associated with Sanfilippo syndrome A by decreasing heparan sulfate-derived oligosaccharides in brain and CSF after dosing.
Reduced heparan-sulfate (HS) in brain in an MPS III KI model.
Reduced heparan-sulfate (HS) in CSF in an MPS III KI model.
Retained comparable brain HS reduction for an Fc variant described as Bizyme Structure 4 with P329S.
Documented Applications
Enzyme replacement therapy for Sanfilippo syndrome A (MPS IIIA) using the disclosed SGSH-Fc fusion protein to decrease toxic metabolite accumulation (heparan sulfate-derived oligosaccharides).
Treatment use involving administering the fusion protein to reduce heparan sulfate-derived substrates in brain and CSF after intravenous dosing.
Use in KI mouse studies to assess brain SGSH-Fc exposure after intravenous dosing of a TfR-binding SGSH-Fc fusion protein and a control SGSH-Fc.
Use in an MPS III (Sgshmps3a×TfRmu/hu) KI model to reduce heparan-sulfate (HS) in brain and CSF after a single dose.
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