Soluble engineered monomeric Fc
Inventors
Dimitrov, Dimiter S. • Ying, Tianlei
Assignees
US Department of Health and Human Services
Publication Number
US-10633447-B2
Publication Date
2020-04-28
Expiration Date
2033-03-14
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Abstract
Fc domains and CH3 domains are disclosed that bind the neonatal Fc (FcRn) receptor and are at least 99% monomeric. Monomeric Fc domain molecules and CH3 domain molecules are disclosed herein that include a monomeric Fc domain or a monomeric CH3 domain and an effector molecule. In some embodiments, the monomeric Fc or monomeric CH3 domain include amino acid substitutions and/or CDR insertions in the beta strands such that they specifically bind an antigen. Methods for using these monomeric Fc domains, monomeric CH3 domains, monomeric Fc domain molecules and CH3 domain molecules are also provided.
Core Innovation
The invention relates to monomeric Fc domains and CH3 domains engineered to bind the neonatal Fc receptor (FcRn) and maintain at least 99% monomeric character. These monomeric Fc domain molecules include amino acid substitutions and complementarity determining region (CDR) insertions in the beta strands to achieve specific antigen binding while retaining FcRn binding for extended half-life.
The problem being addressed is the poor tissue penetration and short half-life of traditional antibody fragments, and the large size of full antibodies that limits their use. Although smaller antibody fragments such as Fab, Fv, scFv, VH, and VHH have been developed, their therapeutic utility is limited by reduced half-lives compared to full-length IgG. Current Fc fusion proteins extend half-life via FcRn binding but are typically dimeric and relatively large (~50 kDa). There is a need for smaller, stable monomeric Fc domains that maintain FcRn binding and can produce small antigen-binding molecules with extended half-life.
Claims Coverage
The patent presents one independent claim focusing on a monomeric Fc polypeptide engineered for antigen binding, specifying key structural and functional features.
Monomeric Fc polypeptide with antigen specificity
A monomeric Fc polypeptide comprising CH2 and CH3 domains that specifically binds an antigen and binds the neonatal Fc receptor. The polypeptide includes mutations in at least one beta strand of CH2 or CH3 domains and/or replacement of a portion of CH2 or CH3 domain by a complementarity determining region (CDR) or specificity determining region (SDR) from a heterologous immunoglobulin variable domain.
Molecular weight less than about 30 kD
The monomeric Fc polypeptide has a molecular weight less than approximately 30 kilodaltons, ensuring a smaller size relative to full-length Fc
Amino acid sequence conformity
The monomeric Fc polypeptide comprises the amino acid sequence of one of SEQ ID NOs: 7-10, representing antigen-binding monomeric Fc domains.
Fusion proteins including monomeric Fc polypeptides
Fusion proteins comprising the monomeric Fc polypeptides linked to one or more effector molecules are claimed, expanding functional utility.
Pharmaceutical compositions comprising monomeric Fc polypeptides
Pharmaceutical compositions including monomeric Fc polypeptides and pharmaceutically acceptable carriers are claimed for therapeutic applications.
The claims cover engineered monomeric Fc polypeptides with antigen binding capacity via beta strand mutations or CDR/SDR replacement, possessing small molecular weight and FcRn binding, along with fusion proteins and pharmaceutical compositions comprising these polypeptides.
Stated Advantages
Monomeric Fc domains have a small size (~27 kD), enabling improved tissue penetration.
These domains retain binding to the neonatal Fc receptor (FcRn), providing extended in vivo half-life compared to smaller antibody fragments.
Monomeric Fc molecules exhibit high stability and solubility, with some variants showing high serum stability and reversible thermal refolding.
Improved expression yields relative to wild-type Fc have been demonstrated, including efficient bacterial expression.
They enable construction of antigen binding molecules with long half-life, small molecular weight, and high binding affinity to any antigen of interest.
Documented Applications
Therapeutic use in treating infectious diseases caused by pathogens including viruses, bacteria, fungi, protozoa, and parasites.
Treatment of cancers, including solid tumors like sarcomas and carcinomas, hematological cancers such as various leukemias and lymphomas, by targeting tumor-associated antigens.
Treatment of autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, systemic lupus erythematosis, and others.
Diagnostic applications including immunoassays to detect antigens, fluorescence-activated cell sorting (FACS), and separation of antigen-positive cells.
Use as fusion proteins incorporating effector molecules such as cytokines, toxins, antibody variable domains, or labels to enhance therapeutic or diagnostic functions.
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