Optimization of Multivalent Bispecific Antibodies and Immunocytokines

Nov 1, 2012 - Immunomedics, Inc., Morris Plains, New Jersey, United States. ‡. Garden State Cancer Center, Center for Molecular Medicine and Immunol...
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Optimization of multivalent bispecific antibodies and immunocytokines with improved in vivo properties Edmund Anthony Rossi, Chien-Hsing Ken Chang, Thomas M Cardillo, and David M Goldenberg Bioconjugate Chem., Just Accepted Manuscript • DOI: 10.1021/bc300488f • Publication Date (Web): 01 Nov 2012 Downloaded from http://pubs.acs.org on December 5, 2012

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Bioconjugate Chemistry

Optimization of multivalent bispecific antibodies and immunocytokines with improved in vivo properties

Edmund A Rossi, †,§* Chien-Hsing Chang,†,§ Thomas M Cardillo, § and David M Goldenberg†,§,‡ †

IBC Pharmaceuticals, Inc.; §Immunomedics, Inc.; ‡Garden State Cancer Center, Center

for Molecular Medicine and Immunology; each in Morris Plains, NJ, USA

*To whom correspondence should be addressed. Immunomedics, Inc. 300 American Road, Morris Plains, NJ 07950. [email protected]. Phone 973-605-8200; Fax 973-605-1340.

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Bioconjugate Chemistry

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ABSTRACT Multifunctional antibody-based biologics, such as bispecific antibodies and immunocytokines, can be difficult to produce with sufficient yield and stability, and often exhibit inferior pharmacokinetics. DOCK-AND-LOCKTM (DNLTM) is a modular method that combines recombinant engineering with site-specific conjugation, allowing the construction of various complex, yet defined, biostructures with multivalency and multispecificity. The technology platform exploits the natural interaction between two interactive human protein binding domains that are modified to provide covalent fusion. We explored the potential application of a new class of IgG-based DNL modules with an anchor domain fused at the C-terminal end of the kappa light chain (Ck), instead of the Cterminal end of the Fc. Two Ck-derived prototypes, an anti-CD22/CD20 bispecific hexavalent antibody, comprising epratuzumab (anti-CD22) and four Fabs of veltuzumab (anti-CD20), and a CD20-targeting immunocytokine, comprising veltuzumab and four molecules of interferon-α2b, were compared to their Fc-derived counterparts. The Ckbased conjugates exhibited superior Fc-effector functions in vitro, as well as improved pharmacokinetics, stability and anti-lymphoma activity in vivo. These results favor the selection of DNL conjugates with the Ck-design for future clinical development.

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Bioconjugate Chemistry

Biomedical research is trending to the development of increasingly sophisticated antibody-based biologics, such as bispecific antibodies, immunocytokines and antibodydrug conjugates. The development of more complex, and less natural, fusion proteins are challenged by problems with yield, stability, immunogenicity and pharmacokinetics (PK). In particular, immunoconjugates based on antibody fragments, including singlechain Fv (scFv), Fab, or other Fc-lacking formats,1 are often difficult to produce with homogeneity and sufficient yield, lack Fc-effector functions, and inherently suffer from short circulating serum half-lives (T1/2). Immunoconjugates of IgG can be produced in high yields, with longer T1/2 and in-vivo stability. Further, intact monoclonal antibodies (mAbs) offer high-avidity bivalent binding with Fc-effector functions, including antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). The enhanced PK of IgG is attributed to two major factors. Its larger molecular size (~150 kDa) precludes renal clearance, which is responsible for the rapid elimination of smaller constructs (130 and 71 days with 100% and 10% survival for 22*-(20)-(20) and 22-(20-(20), respectively (P