BD FACSymphony™ helping unravel virus-specific T-cells in human cancer immunotherapy
This month’s interview features Dr. John Connolly, Chief Scientific Officer of Tessa Therapeutics, Singapore. Dr. Connolly is a leading immunologist whose research focuses primarily on target discovery for immune modulation. At Tessa Therapeutics, Dr. Connolly and his team are working on virus-specific T-cells (VSTs) and exploring their potential use in human cancer immunotherapy. As Dr. Connolly explains in this interview, the BD FACSymphony™ high parameter flow cytometer is a vital and an extremely useful tool for his research.
1. Please share with us about Tessa Therapeutics’ vision and direction in the near-term and long-term
Tessa Therapeutics is a clinical stage cellular immunotherapy company committed to solving the solid tumor challenge. If we take a step back, we see ourselves as an immunology company that is focused on cancer. We aim to harness the entire immune response and redirect it against tumors. One of the key questions that we asked early on is what is the right kind of immune response for actual attacks on cancer cells? There are many types of immune response, for instance, allergic, anti-bacterial, anti-fungal, and autoimmune responses. But particularly when we look at anti-viral immunity, it shares many of the qualities of a successful anti-tumor response. It shows incredible precision, potency, and penetration in the treatment of solid tumors. These are the attributes we are looking for in terms of anti-tumor immunity. Tessa focuses on redirecting anti-viral immunity towards tumors by harnessing its Virus-Specific T cell (VST) platform technology. VSTs are generally used to fight off viral infections and they last for a very long time. VSTs have the ability to recognize and kill infected cells while activating other parts of the immune system for a coordinated response. Gene-marked VSTs have demonstrated long persistence of over ten years¹. Just as the immune response to chicken pox lasts for a person’s entire life, this is also true for the response to many other viruses. We are redirecting VSTs against tumors and initiating a multi-cellular, anti-viral response that targets solid tumors. We do that through a number of methods, primarily by adding Chimeric Antigen Receptors (CARs) to redirect the anti-viral response of VSTs or by armoring VSTs, for example to avoid the suppressive effects of Transforming Growth Factor beta (TGF-B).
2. How is Tessa going to move into the next stage of manufacturing cell products?
At Tessa, we believe in evolution over engineering. We aim to generate VSTs in the most natural way possible and cultivate these cells with the right properties, such as the ability to penetrate tumors, high durability in a tumor microenvironment, and long-term persistence in hunting and killing tumor cells. We set up competition (cultures of effectors and targets) and allow them to kill their targets. As the VSTs kill the targets, they divide and expand; we can then influence conditions, like changing oxygen concentration and putting in immunosuppressive cytokines so that only the strongest, most resistant ones make their way. By doing so, we are able to optimize our cells through an evolutionary process.
3. How does Flow Cytometry (FCM) play a part in this?
Flow cytometry is a core technology of most immunology labs, without which our understanding of immunology in general would not be the same. From our standpoint, there are two areas in which FCM plays a critical role. The first is in the characterization of VSTs. As much as we understand anti-viral immunity, we don’t fully understand what makes these VSTs so special. High dimensional FCM is critical in comparing conventional activated T cells with VSTs and identifying the characteristics that give VSTs all those powerful anti-tumor properties we are looking for. The second key area is in the understanding of the quality of the immune response which correlates to clinical efficacy in patients. Even though VSTs are there to initiate an anti-tumor response, other cells play an important role. In order to fully understand the mechanism of action, we use a high dimensional FCM to look at all cellular populations pre- and post-treatment.
4. Why did you opt for the BD FACSymphony™ A5 to tackle this high dimensional topic?
BD has been a pioneer since the 70’ies in FCM. The A5 offers many advantages over other products in terms of high dimensional flow, including pushing the limit of available colors. The BD FACSymphony™ A5 represents cutting edge high dimensional FCM. This makes it a perfect system for Tessa to monitor our clinical trials.
5. How do you currently assess clinical safety and efficacy of these cell products? Is FCM part of that?
VSTs have demonstrated a remarkable safety profile in the clinic, with hundreds of patients treated and no cases of severe toxicities. It is one thing to produce cells quickly but it is actually more important to produce potent cells that function correctly. Understanding the T cells that come out of a process – their ability to develop into long term memory cells and their ability to produce granzymes and kill targets – are all things that can be addressed by FCM. We only want to move forward with a product for which we have a good level of quality control.
6. Do you see any challenges or bottlenecks in the cell therapy space?
The process is always a bottleneck. In the cell therapy space there is a lot of great technology, particularly in the synthetic biology field, but realistically if companies want to scale from Phase 1 to Phase 2, Phase 2 to Phase 3, or Phase 3 to commercialization, there are enormous gaps in their abilities to do that and maintain potency. Companies can always develop a faster process and a more robust bulk yield process but being able to do that and still maintain potency is a huge challenge in the field. This is why Tessa is pushing this field forward and remains focused on process development.
7. Designing a high dimensional panel for the BD FACSymphony™ can be quite a difficult process. How do you find the panel development with BD so far?
To date, panel development with BD has been very good and I think this is true for any kind of high dimensional FCM – companies need a good partner in the development of assays. Understanding the density of the antigens on the surface of the cell as well as the relative expression of these proteins on different cell types are critical for any kind of high dimensional panel design. BD has put a lot of time into developing real maps of immune cells showing how the antigen density and relative expression are distributed and that allows us to work with Bob Balderas and his team in putting together very good flow panels. We had a great experience.
8. What do you envision in the next generation of FCM to help you further your work?
I think the next generation of FCM should start to tackle gene expression. The competition is going to get broader – when it comes to combination protein and RNA analysis on the same platform. I know BD is approaching single cell sequencing and it is fully capable of both protein and RNA analysis. Moving away from fluorophores into DNA-labelled antibodies and barcode-labelled antibodies would be important in the future.
¹ Heslop H et al. Blood 2010
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