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Novel enzymatic methods for the site-specific modification of therapeutic proteins

English title Novel enzymatic methods for the site-specific modification of therapeutic proteins
Applicant Schibli Roger
Number 112437
Funding scheme Project funding (Div. I-III)
Research institution Institut für Pharmazeutische Wissenschaften ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Inorganic Chemistry
Start/End 01.05.2006 - 30.04.2008
Approved amount 121'153.00
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All Disciplines (4)

Discipline
Inorganic Chemistry
Pharmacology, Pharmacy
Biochemistry
Organic Chemistry

Keywords (10)

Radiolabeling; Site-Specific; Antibody; Tumor Targeting; Enzyme; Transglutaminase; Enzymatic protein-labeling; MRI; optical imaging; antibodies

Lay Summary (English)

Lead
Lay summary
Background: Cancer is responsible for more than 20 % of deaths in developed countries (www.cancer.org). Specific, noninvasive targeting of cancerous sites by means of therapeutic proteins such as monoclonal antibodies (MAb) has become an indispensable tool for therapy. Empowering the efficacies of such antibodies with diagnostic and therapeutic entities is of highest interest to understand molecular interactions and improve therapy. Particularly, radiometal labeled mAbs have proven to play a crucial role in detection and treatment of aggressive metastatic diseases because of their negligible side effects and high efficacy. However, chemical labeling methods available today for the decoration of proteins with probes of interest suffer from serious limitations (e.g. loss of protein activity due to unspecific or over-labeling).Working Hypothesis: Toward this goal, we aim to improve and simplify the site-(amino acid)specific functionalization and (radio) labeling of proteins under physiological conditions using the enzymatic activity of the family of transglutaminases (TGase; EC-number 2.3.2.13). TGases form very stable isopeptidic bonds between the side chains of glutamine and lysine in peptides and proteins. Therefore, we reasoned to attach covalently and specifically Lys- or Gln-substrates bearing various diagnostic and therapeutic probes (e.g. PET, SPECT, optical and MRI) to proteins of interest. Compared to chemical modification we expect modification via TGase to be: (i) more site-specific, (ii) more gentle to the precious protein, (iii) reliably reproducible, (iv) stable and (v) versatile.Goals: The main goal of the presented project is to prove and assess the superior characteristic of enzymatic radiolabeling of therapeutic proteins with different diagnostic and therapeutic radionuclides as well as the development of new, non-radioactive targeting immunoconjugates for MRI and optical imaging. For this purpose, we plan to evaluate and test different TGase under various reaction conditions for their efficiency, substrate specificity and site-specificity. Then, the focus will be on the development, synthesis and characterization of new bifunctional chelating systems (BFCAs) tailor-made for the TGase approach. The most effectiveTGase(s) and the most promising BFCAs and the radiometal complexes thereof (i.e. with Cu-64/67, Tc-99m, In-111, Lu-177, Re-186/188) will be selected for modification of in-house used and available therapeutic proteins(chCE7 and Fab2-fragments thereof) and further assessed in vitro (cellularlevel) and in vivo (mouse tumor model). The insights gained from the radiolabeled immunoconjugates will be directly employed to the development of BFCAs for other metal ions such as e.g. Gd3+, Eu3+, which exhibit paramagnetic (and/or luminescent) characteristics for MRI and/or optical imaging.
Direct link to Lay Summary Last update: 21.02.2013

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Associated projects

Number Title Start Funding scheme
120158 Novel enzymatic methods for the site-specific modification of therapeutic proteins 01.05.2008 Project funding (Div. I-III)

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