New Strategies For Therapeutic Antibodies – Synthetic bispecific antibodies & Antibody-Drug Conjugates with controlled drug loading. General methods for unexplored ADCs and personalised therapies.

Project Information

NSFTA

Grant agreement ID: 838703

DOI

10.3030/838703

Project closed

EC signature date 11 April 2019

Start date 15 January 2020

End date 9 March 2022

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 224 933,76

EU contribution

€ 224 933,76

Coordinated by

UNIVERSITY COLLEGE LONDON
United Kingdom

Periodic Reporting for period 1 - NSFTA (New Strategies For Therapeutic Antibodies – Synthetic bispecific antibodies & Antibody-Drug Conjugates with controlled drug loading. General methods for unexplored ADCs and personalised therapies.)

Reporting period: 2020-01-15 to 2022-01-14

Summary of the context and overall objectives of the project

Antibodies can recognize invaders and call immune cells in order to destroy them. They notably recognize cancer cells. It is possible to attach toxic drugs to an antibody so they are driven directly to the cancer cells to destroy them, sparing the healthy cells and avoiding secondary effects.
An antibody is a chemical structure possessing “chemical hooks” on its surface. Chemical reactions allow attaching interesting payloads (e.g. drug) to these antibody's hooks. However, antibodies possess on their surface a multitude of identical hooks. As a consequence, it is hard to have perfect control over the number and location of the payloads being attached. For instance, if the aim is to attach only two payloads per antibody, it will rather end up with a "mixture", a statistical distribution of antibodies having 0 or 1 or 2 or 3 or 4 elements attached.

The lack of control over the number of payloads per antibody is problematic regarding multiple aspects: 1. It is hard to generate and identify the optimal ratio payload/antibody for the best therapeutic result. 2. Regarding validation of the production process, homogeneity is preferred. Ideally, only one type of ratio should be obtained. 3. New developments consist in attaching different types of payloads to the antibody, in order to get a synergistic effect. The challenge is improved when attaching two different drugs to the antibody.

Besides, “bispecific antibodies” are a new sort of antibody, able to recognize two different targets. They are kind of a “mix” between two antibodies. Their capacity to act simultaneously on two different targets is very useful for cancer treatment, but they are made through bioengineering: an expensive and time-consuming process, especially when various bispecific antibodies are meant to be evaluated (“screening” process). Thus, a faster method to create bispecific antibodies would be helpful to speed up screening processes.

Developing chemical methods that allow attaching active compounds to the antibody with perfect control is of huge importance. In the long-term view, this should allow to develop optimized treatments and thus benefit patients. Regarding the easier and faster generation of bispecific antibodies, this could highly improve the number of bispecific antibodies evaluated and thus speed up the finding of new treatments.

Overall objectives:
1. To develop a method that allows attachment of one type of payload to an antibody in a controlled manner. Notably, having access to various and rare drug/antibody ratios with the same generic method is a pursued goal.
2. To develop a method that allows attachment of different payloads to an antibody in a controlled manner.
3. To develop a fast and generic method to generate bispecific antibodies without requiring bioengineering, but rather using chemical reactions.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

After a first year, highly disrupted by COVID pandemic, compounds were made in order to modify the antibody with only two payloads, solely on the Fab fragment (the two upper parts of the Y-shaped antibody which are able to recognize a target). However, we were not able to specifically modify the Fab fragments. First compounds were made and evaluated for the controlled modification of antibodies.
The quarantine period has been an opportunity to write a review on immunotherapy and chemical biology.

During the second year, a battery of new compounds was made in order to develop a generic method that would give access to different drug/antibody ratios in a controlled manner. Optimisation was a success - antibodies could be modified in a controlled way, with 2, 4 or 6 copies of a payload, or even 4 copies of a payload and 2 copies of another payload.
We also applied the methodology to Fc fragment (which is responsible to trigger an immune response), and to Fab fragments (the ones allowing the antibody to recognize its target). Again, after optimization, we managed to generate Fc of Fab fragments having 1, 2 or 3 copies of a payload attached to them, or 2 copies of one payload and one copy of another payload attached.

In parallel, new compounds were designed, synthesised, optimised in order to generate a bispecific antibody only using native antibodies and chemical methods (no engineering). After months of work, a method was developped that allows the generation of a bispecific antibody from two native antibodies in only few days! Biological evaluation is ongoing by collaborators and not included in the project timeframe.


RESULTS

- A review paper "Enabling the next steps in cancer immunotherapy: from antibody-based bispecifics to multispecifics, with an evolving role for bioconjugation chemistry" (RSC Chem Bio, 2022, 3, 140-169). Meant to share ideas in order to improve the development of new cancer immunotherapies

- A chemical biology method was developed to attach payloads on a full antibody, Fab fragment or Fc fragment in a controlled manner. A scientific paper reporting this work will be submitted soon.

- A chemical biology method was developed to generate bispecific antibodies only from native antibodies, and solely using chemical reactions. This work will also be published soon.

We will disseminate results in scientific conferences even after the end of the project funding period as well as on the project website.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Many methodologies to generate antibody-drug conjugates with 2, 4 or 8 payloads attached already exist. However, they generally give access to only one of these ratios. Some methods generate a mixture of multiple species. Attaching two different types of payloads in a controlled manner is rare.
The method developed in this project brings more control and flexibility, with three possibilities of monofunctional ratios and one possibility of bifunctional ratio. Antibodies are homogeneously modified (no mixture). The developed method gives access to a wider range of antibody-drug conjugates, to their optimization, and broadens the perspective to find optimal treatments.

The method could be adapted to Fab fragments. Methods allowing modifications of Fabs to generate Fab-drug conjugates already exist. But we were able to generate Fab-conjugates with four different payload/Fab ratios (1, 2, 3 or 2+1) with only one generic method. Such flexibility has not been described so far. Our method will broaden the range of Fab-conjugates, hopefully giving access to optimized treatments.

The modification of Fc fragment is not highly reported in the literature. The flexibility and control offered by our method are really innovative. It permits to combine an Fc fragment with various ligands to generate what could be named “synthetic antibodies” (a molecule that recognizes a target and is able to trigger an immune response, but which is not a natural antibody). This could be particularly useful when no natural antibody exists for a specific target and open access to a range of new treatments. Regarding economic impact, patenting is envisioned.


BsAbs are particularly used in cancer treatment. But their production is time and cost-consuming. That is why our method is a breakthrough – it allows the fast and versatile production of BsAbs only using native antibodies and chemical reactions! No such chemical method has been published so far. We expect an important impact on the scientific community, as it could reduce the costs and speed up the process of BsAb production and screening, in turn accelerating the discovery of new treatments.

General overview of the project

Scheme of the controlled modification of antibodies