With Sara Mangsbo, Senior Associate Lecturer at Uppsala University Summary by Candace Kastanis
Candace Kastanis visits the highlights of this presentation by Sara Mangsbo, Senior Associate Lecturer at Uppsala University
The co-founder of Strike Pharma, Sara Mangsbo PhD, opens with the concept and project details regarding introducing neoantigens into dendritic cells through a bispecific antibody design.
This sets up the premise for the basis for the ADAC’s (Adaptable Drug Affinity Conjugates) Targeting CD40 Proof of Concept and profile that she outlined for the audience.
Challenges with Tumor Vaccines
Mangsbo enters into the presentation with the fact that non-live vaccines, subcomponent, and/or peptide vaccines require an investment to enter into formulation in an effort to provide adjuvant and antigen stability.
She goes on to say that live vaccines are interesting subjects because they induce a cellular immunity or T cell response, but they also show an immunodominant response that responds more to the vector.
Therefore, for the project featuring the peptide vaccines, the goal was to create an adaptation to a scenario where flexibility is a feature.
Challenges with CD 40 Antagonistic Bodies
The focus here was to explore and provide solutions to the core question regarding CD40 antibodies. Can you make the antibodies be effective when they do not link to an antigen?
Mangsbo illustrates how CD40 was historically used as an intravenous drug without any focus on the antigen. She then points out how the dendritic cell targeted by the antibodies which should lead to an activation of the T cells.
However, T cells also requires T cell presentation. However, if there is no antigen, we may realize we are in a situation where the antibody doesn’t do anything.
If it becomes impossible to reach T-cell activation with enough antibodies because of a narrow therapeutic window these antibodies have, then it could create adverse side effects such as possible liver toxicity and cytokine release.
We risk not achieving signal 1, 2, or 3 to achieve T cell activation. A way around this problem is to use intertumoral delivery of these antibodies. However, it can lead to an expansion and recruitment of myeloid derived tumor cells.
CD40 Benefits in the Antigen Presentation Pathway
Mangsbo expanded on the benefits of using CD40. In doing so, she framed the following question to help set up their research findings.
How do you do the drug development without linking to cargo molecules, but instead provide an adaptable platform for drug delivery?
This is an important question and the answers set up the foundation for the project goal of achieving a viable driver for preclinical development.
The framework around working with peptides highlighted their beneficial characteristics such as:
The challenges with working with peptide-based vaccines were also highlighted:
The solution brought forward in the presentation was to involve bispecific antibodies to deliver peptide molecules to the dendritic cells through CD40 (hence, ADAC). These provide the following characteristics:
With the bi-specific design, the antibody can interact with the CD40.
They can then pull in the materials, attach to the antibody thereby allowing the peptide delivery to complete the process.
This paired with improved activation signal that leads to improving the co-stimulation properties.
CD40 Design and Mechanism of Action Based on Isotope Choice
This helps the audience understand the activity of the isotype rigid iG2 isotype matters a great deal. Depending on which isotype it binds to, it can lead to potentiation.
Applications included exploring the potential for agonistic activity based on the various isotope bond and its correlating activity.
They took bones from CD40 transgenic mice, isolated bone marrow dendritic cells and cultured them to become immature dendritic cells. This made it possible to add antibodies to the cells and study their behavior.
Experiment 1: Proof of concept
Co-culture experiments included using the dendritic cells described above.
They studied how the parental antibodies, as well as bispecific, stimulated the dendritic cells. The goal was to see if they could retain bispecific antibodies with agonistic activity.
The results showed a very anti-agnostic in 1G1 format, but very agnostic IG2 format. The co-culture experiment revealed that all bispecific antibodies have agonistic activity retained.
Testing CD8 T-cells Result
The research team performed a co-culture of the dendritic cells delivered with the peptide and the antibody mixed with a hybridoma cell line (T-cell receptor) which triggers T-cell activation.
When looking at T-cell activation co-culture where they express CD40, they noticed they all display t-cell activation pattern. Also, they observed a slight dependence on isotype.
*In a controlled experiment involved using cells that do not express cd40, they did not see any inactivation of the T-cells.
CD40 Research In Vivo
The research showed no indications of target medial expansion in vivo.
Transferring to CD40 bone marrow dendritic cells or wild type dendritic cells highlighted the following attributes and findings:
The project confirmed they were able to assign CD40’s bispecific antibodies for professional antigen cells.
They were able to establish improved T cell expansion in both in vitro and in vivo, and high affinity. Through this combination of CD40 antibodies, they can leverage the CD40 stimulation efficacy in the clinic.
The ADAC strategy would allow for flexible but targeted antigen delivery strategy based on synthetic peptides.
This enables the research team to further narrow their focus on a specific drug design and protein manufacturing process for preclinical drug development.
