The "CAR-T" revolution: in Paris, the biotech Cellectis is working hard against cancer - France 24

Paris (AFP)

It is a promise that makes doctors and patient associations dream.

With its molecular scissors, the French biotech Cellectis wants to treat recalcitrant leukemia and cancers, illustration of a revolution underway.

It is in an ultra secure laboratory in the 13th arrondissement of Paris that cell editing begins, to arm them against cancer cells.

But before advancing further in these sanitized premises, it is better to revise your vocabulary.

Because Cellectis works on CAR-T cells, or "chimeric antigen receptor T cells".

In lambda language, our immune system has T lymphocytes to protect itself, which identify and destroy foreign cells.

"The T cell is extraordinary. It is a sort of little soldier, capable of repeatedly killing and multiplying," explains André Choulika, the enthusiastic researcher who founded Cellectis more than twenty years ago.

However, for several years, scientists have known how to genetically modify these cells to express a specific protein on their surface.

"We put a little researcher on this T cell, which will recognize the cancer cell", decrypts André Choulika.

This cutting-edge technology allows tumors to be targeted very precisely without affecting other organs, unlike chemotherapy.

Technicians work on CAR-T cells in a laboratory of the French biotech Cellectis, September 23, 2021 in Paris THOMAS COEX AFP

Two treatments based on CAR-T are already on the market for certain cancers.

These are Yescarta, the American laboratory Gilead, and Kymriah, developed by the Swiss company Novartis.

In these two cases, the T cells are taken from the patient, before being edited, personalized and multiplied in laboratories, and finally reinjected.

- "New optics" -

Cellectis is developing “off-the-shelf” CAR-T: not taken from the patient, but from cell banks, they can be stored at very low temperature in hospitals, then injected into patients as needed.

This would make the therapies potentially less burdensome and faster to produce.

The challenge is big.

"There is a fundamental principle in medicine: one cannot take the cells of a donor and inject them into a recipient", otherwise at the risk of causing a graft versus host syndrome, a very serious syndrome, underlines André Choulika .

Technicians work on CAR-T cells in a laboratory of the French biotech Cellectis, September 23, 2021 in Paris THOMAS COEX AFP

To avoid this, Cellectis therefore reprograms the cell: "We give it a new perspective: it only sees one thing, the cancerous cell," he continues.

Biotech, which has production sites in Paris and the United States, had significant success in 2015, treating a baby with leukemia.

Since then, some 120 patients have been treated with products resulting from its research, currently in clinical trials, says its founder.

For specialists in the sector, the CAR-T technology is highly promising: "It is one of the next technological revolutions in the world of health," says Loïc Plantevin, of the consultancy firm Bain et Company.

"We are at the heart of personalized medicine. In the next ten years, we will see more and more treatments, with therapies that are more and more effective and easy to use."

But managing to edit genes requires tools, in this case RNA, this ribonucleic acid that has become famous thanks to anti-Covid vaccines.

Cellectis thus manufactures these RNA molecules in part of the Paris laboratory, which is then sent to the production site across the Atlantic.

It will turn, after many more operations, into molecular scissors capable of cutting a fragment of DNA in T cells.

“At a time when global demand for RNA exploded during the Covid, it was all the more useful to manufacture it in-house,” recalls Leopold Bertea, vice-president of technical operations.

A technician works on CAR-T cells in a laboratory of the French biotech Cellectis, September 23, 2021 in Paris THOMAS COEX AFP

Biotech is counting on a first commercialization planned for 2023 or 2024. Eventually with the possibility of potentially reducing the prices of these expensive therapies, which cost several hundred thousand euros per dose.

© 2021 AFP