Nicolas Thiault, Ph.D.

What if there is a new immune cell that could be engineered to safely kill tumor cells and cure cancer?

FUNDED BY: The generosity of the LJI Board Director Emeritus Larry Spitcaufsky and Tiki Spitcaufsky

What was the goal of your SPARK project?

Recently, we discovered a new cellular actor in the immune system. These cells, called DNT, possess unique features that distinguish them from ones currently used in immunotherapies. Indeed, we have strong evidence showing that these cells are potent killer cells without inducing tissue damage or organ failure. However, before this DNT cell-based therapeutic approach can be tested in clinical trials, we critically require proof-of-concept in mouse models.

A cutting-edge technology, chimeric antigen receptor (CAR) T cells, has shown interesting promise in the field of cancer immunotherapy, allowing us to hijack resistance mechanisms developed by solid tumors. Unfortunately, CAR T cells are often associated with severe toxicity and a high failure rate in certain types of cancers when associated with the mainstream immune cells, currently used in immunotherapies. My goal is to apply existing CAR T cell technology to new immune cells, discovered at LJI, called double negative T (DNT) cells in order to design a superior therapeutic strategy aiming to eliminate solid tumors with a lower toxicity.

Did you face any challenges?

Unfortunately, because of the COVID-19 pandemic and multiple reagent shortages, the in vitro experiments I needed to run were delayed, so I was
granted a six-month extension in January 2022. During this period, I have received all critical components for the in vitro and in vivo experiments to validate our working hypothesis. I can now address whether engineered DNT cells can safely kill tumors and cure cancer in vivo. I look forward to providing a final update this fall.

SPARK project updates:

One of the main challenges facing CAR T cell technology is the engineering of the DNT cells as carriers of the exogenous receptor. As such, my first operation was to perform a retrovirus-based transduction protocol to integrate an exogenous DNA construction coding for an anti-CD19 CAR
into DNT cells genome. I also worked on engineering the target of anti-CD19 CAR DNT cells. Although the optimization of these different protocols doesn’t represent any potential clinical relevance, they are yet essential to conduct the main upcoming in vitro and in vivo experiments. Nonetheless, such characterization of the DNT cell biology has never been described in fundamental nor translational research and would be worth considering for further investigation.

The second step consisted of testing the anti-tumor capacity of the anti-CD19 CAR DNT cells in vivo and compared their suspected efficiency to the mainstream killer CD8 T cells, which are profusely used in current Adoptive Cell Transfer (ACT) therapies against cancer. I have observed that DNT cells bearing the anti-CD19 CAR-injected six days after tumor implantation have tremendously controlled the growth of the melanoma
tumor cells expressing the CD19 protein.

This greatly enhanced the survival of mice bearing tumors compared to the untreated group. Remarkably, the unique injection of these cells has even led to a partial remission of cancer. Moreover, I have observed that anti-CD19 CAR DNT treatment exhibits a superior ability to eradicate tumors than the one using mainstream killer CD8 T cells. These preliminary results might represent a hope for the development of better therapeutic strategies to treat cancer in a global fashion, given the versatility of the DNT cells.

What’s next for this project?

Thanks to my SPARK award, I may have generated some very promising data, which suggest that DNT cells are a new player in anticancer immunotherapies. Nevertheless, the B16 melanoma mouse model, although useful, is physiologically distant from human cancer. Therefore, it is essential to confirm these preliminary results into other mouse models that reflect more human disease. As such, I will repeat these experiments using human-derived cells transplanted into transgenic “humanized” mice and DNT cells obtained from healthy donor blood draws. Moreover, together with Dr. Hilde Cheroutre, I secured a $350,000 grant from a private family in January 2022 to build on this work in the context of glioblastoma (brain cancer) in mice and humans.

What’s next for Nicolas?

I wish to pursue finishing the in vitro experiments in order to prove a direct lethal hit to the tumor cells by DNT cells and address the toxicity in genetically mismatched settings. I also would like to start implementing the framework to test our hypothesis using human samples.

Finally, with our new funding, I have started to repeat this set of experiments in glioblastoma cancer (mouse and human), and we are already showing encouraging results.