Enabling The Targeted Delivery Of DNA G-quadruplex Ligands using a Novel Antibody DAR-1 Platform
Lead Research Organisation:
University College London
Department Name: School of Pharmacy
Abstract
DNA is often assumed to be a double helix, the "twisted ladder" structure which was first proposed by Watson and Crick in 1953. However, it is not widely known that DNA can adopt many different shapes. Since the structure of DNA was first revealed, much research has shown that DNA takes many different forms and these are related to the role it plays in biology.
DNA is comprised of four bases, often described as the "building blocks" for life because they encode all the information required to build and maintain an organism. The sequence of these four bases (adenine, guanine, thymine and cytosine) is what defines us as humans and what makes us different to bacteria, yeast and plants. DNA sequences which contain lots of the base guanine can form alternative secondary structures which instead of appearing like the normal "twisted ladder" of two strands, are a very tightly packed "cube" of four strands of DNA. We call these structures G-quadruplexes. Sequences of this type are also widespread throughout the human genome, exist in cells and have been shown to play a role in gene expression and defining how long our cells live. These DNA sequences are found in cancer-causing genes more than other genes and a lot of research has been dedicated to designing drug-like compounds to target G-quadruplex structures. Despite these advances in knowledge, targeting these G-quadruplex structures specifically has not been achieved. We know that unspecific but potent compounds can be made more specific for certain types of cells by connecting them to antibodies. Antibody-drug conjugates are a class of biological drugs that can be used as a targeted therapy to treat conditions such as cancer. By connecting a drug-like molecule to an antibody, the antibody will be able to find the specific diseased cells and leave healthy cells alone. This enables us to have a drug that targets only the cells that need the treatment, for example between cancer and healthy cells. Importantly, this overall approach could be applied to many different diseases and conditions.
The central aim of this proposal is to develop antibody drug conjugates for compounds that target G-quadruplex DNA. Our previous work has given us an understanding of strategies and tactics for connecting drugs to antibodies. We have preliminary data to show different ways to connect drugs to antibodies. We will develop antibody drug conjugates, characterise their properties and their ability to release their payload specifically to only diseased cells. The outcomes and potential impact of this project will advance our understanding of how to connect drugs to antibodies (and will be applicable to other biomolecules). The work will also develop the first antibody drug conjugate with a G-quadruplex binding compound as the payload. The outcomes will reveal a new family of antibody drug conjugates, with a pathway for applying the knowledge to other systems.
DNA is comprised of four bases, often described as the "building blocks" for life because they encode all the information required to build and maintain an organism. The sequence of these four bases (adenine, guanine, thymine and cytosine) is what defines us as humans and what makes us different to bacteria, yeast and plants. DNA sequences which contain lots of the base guanine can form alternative secondary structures which instead of appearing like the normal "twisted ladder" of two strands, are a very tightly packed "cube" of four strands of DNA. We call these structures G-quadruplexes. Sequences of this type are also widespread throughout the human genome, exist in cells and have been shown to play a role in gene expression and defining how long our cells live. These DNA sequences are found in cancer-causing genes more than other genes and a lot of research has been dedicated to designing drug-like compounds to target G-quadruplex structures. Despite these advances in knowledge, targeting these G-quadruplex structures specifically has not been achieved. We know that unspecific but potent compounds can be made more specific for certain types of cells by connecting them to antibodies. Antibody-drug conjugates are a class of biological drugs that can be used as a targeted therapy to treat conditions such as cancer. By connecting a drug-like molecule to an antibody, the antibody will be able to find the specific diseased cells and leave healthy cells alone. This enables us to have a drug that targets only the cells that need the treatment, for example between cancer and healthy cells. Importantly, this overall approach could be applied to many different diseases and conditions.
The central aim of this proposal is to develop antibody drug conjugates for compounds that target G-quadruplex DNA. Our previous work has given us an understanding of strategies and tactics for connecting drugs to antibodies. We have preliminary data to show different ways to connect drugs to antibodies. We will develop antibody drug conjugates, characterise their properties and their ability to release their payload specifically to only diseased cells. The outcomes and potential impact of this project will advance our understanding of how to connect drugs to antibodies (and will be applicable to other biomolecules). The work will also develop the first antibody drug conjugate with a G-quadruplex binding compound as the payload. The outcomes will reveal a new family of antibody drug conjugates, with a pathway for applying the knowledge to other systems.
Technical Summary
G-rich regions of DNA can form alternative secondary structures called G-quadruplexes, which have been shown to exist and act as molecular switches in cells. GQs have been the target of many different small molecules and although there have been significant advances in this field, we still do not have ligands that can target specific cells.
Our aims are to create a set of new antibody drug conjugates (ADCs) based on trastuzumab/Herceptin with GQ ligands as the payload. The project will test this using a range of synthetic chemistry, biophysical and cell biology techniques.
Our team has already developed several chemistries and methodologies for the creation of ADCs. We will build on this preliminary work and expand this by the creation of ADCs with a drug to antibody ratio of one. We will combine synthesis of strained alkyne bearing tetra-dibromopyridazinedione-antibody conjugates and azide-functionalized GQ-interacting ligands with linkers that are designed to be cleavable in distinct environments: acid-cleavable, thiol reducible and enzyme-cleavable. Our novel ADCs and intermediates will be characterised in vitro and in HER2 positive (BT474) and HER2 deficient cells (MCF7).
The new chemistries that will be developed in the context of developing this GQ-targeting platform will serve as a general means for conjugating highly hydrophobic molecule to antibodies or proteins where the loading may only be limited to only one drug/ligand per antibody, thereby opening up new avenues in small-molecule-protein conjugation.
Our aims are to create a set of new antibody drug conjugates (ADCs) based on trastuzumab/Herceptin with GQ ligands as the payload. The project will test this using a range of synthetic chemistry, biophysical and cell biology techniques.
Our team has already developed several chemistries and methodologies for the creation of ADCs. We will build on this preliminary work and expand this by the creation of ADCs with a drug to antibody ratio of one. We will combine synthesis of strained alkyne bearing tetra-dibromopyridazinedione-antibody conjugates and azide-functionalized GQ-interacting ligands with linkers that are designed to be cleavable in distinct environments: acid-cleavable, thiol reducible and enzyme-cleavable. Our novel ADCs and intermediates will be characterised in vitro and in HER2 positive (BT474) and HER2 deficient cells (MCF7).
The new chemistries that will be developed in the context of developing this GQ-targeting platform will serve as a general means for conjugating highly hydrophobic molecule to antibodies or proteins where the loading may only be limited to only one drug/ligand per antibody, thereby opening up new avenues in small-molecule-protein conjugation.