CAR-T Cell Therapy

The human immune system fights disease using special defense cells known as T-cells. In cancer, this system often fails because cancer cells disguise themselves. CAR-T cell therapy works around this problem by genetically reprogramming a patient’s T-cells in the lab. The modified cells are given an artificial recognition site — the so-called chimeric antigen receptor, or CAR for short — that is specifically designed to match a feature of the cancer cells. Once back in the patient’s body, these cells seek out the cancer cells and destroy them. This makes it a living drug: it is not a chemical that works, but the modified cells themselves.

Why CAR-T cell therapy is a different category of treatment

Classic cancer therapies such as chemotherapy often attack anything that divides quickly — including healthy tissue. CAR-T cells, by contrast, are programmed for a specific target. This makes them more precise and more effective for certain patients in whom other treatments have failed.

The durability of the effect is especially striking. T-cells can multiply within the body and build up what is known as immunological memory. This means that if cancer cells reappear, the body can respond more quickly. In some patients with certain forms of blood cancer who were considered to have exhausted all treatment options, no cancer cells were found for good after CAR-T treatment.

At the same time, it is one of the most expensive treatments currently available. A single treatment cycle can cost the equivalent of several hundred thousand euros. This is because the cells are manufactured individually for each patient — mass production is not possible.

From the patient’s blood to a tailor-made cell weapon

The process begins with T-cells being drawn from the patient’s blood. These cells are sent to a specialized laboratory, where scientists use a virus — which serves as a tool but has itself been rendered harmless — to introduce a new gene into the T-cells. This gene contains the blueprint for the CAR recognition site.

The modified cells are then multiplied in the lab until hundreds of millions of them are available. They are then frozen, transported back to the clinic, and administered to the patient via infusion. Before the infusion, the patient usually receives mild chemotherapy — not to fight the cancer, but to make room in the immune system so that the CAR-T cells can establish themselves more effectively.

The treatment carries serious risks. If many cancer cells are attacked at the same time, the immune system can overreact and trigger what is known as a cytokine storm — a dangerous inflammatory reaction throughout the body. Patients are therefore closely monitored after the infusion, often for days in an intensive care unit.

CAR-T cell therapy in news and products

The first CAR-T drugs were approved in the United States in 2017, followed shortly afterward by approval in Europe. The products go by names such as Kymriah (manufacturer: Novartis) or Yescarta (manufacturer: Kite Pharma, now Gilead). Both are approved for certain forms of leukemia and lymphoma — cancers affecting the blood and the lymphatic system.

CAR-T cell therapy regularly appears in business news in connection with approval decisions, clinical trials, or acquisitions in the biotech sector. Many start-ups and large pharmaceutical companies are investing in the next generation of these therapies. A central goal is to make CAR-T cells effective against solid tumors as well — that is, cancerous growths in organs such as the lungs or intestines — which has so far proven difficult to achieve.

Efforts are also underway to develop so-called “off-the-shelf” products: CAR-T cells that no longer come from the patient themselves but are manufactured from donated cells and can be used for many patients. This would drastically reduce costs and make the treatment accessible to far more people.