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Was Sie heute wissen sollten

von NFI Redaktion

In 1996, Doug Olson was diagnosed with chronic lymphocytic leukemia (CLL), a type of cancer that begins in white blood cells. Due to the slow growth of this cancer, his doctor decided to monitor him and wait to begin treatment.

However, when Olson’s cancer started to grow a few years later, he had to undergo several rounds of chemotherapy. Then, in 2009, the tumor changed. Chemotherapy was no longer effective. Olson’s doctor, Dr. David Porter, recommended a bone marrow transplant. However, none of Olson’s siblings were a good match.

„The news just kept getting worse,“ Olson recalls.

Then, Olson’s doctor suggested a clinical trial for a new type of cancer treatment. Specifically, it was an immunotherapy called CAR-T cell therapy. The goal was to reengineer Olson’s immune cells in the lab to turn them into weapons to hunt down cancer cells.

CAR-T cell therapy can work when other treatments fail. Unlike chemotherapy and radiation, which kill both healthy and cancerous cells, immunotherapy targets tumors more specifically.

CAR-T cell therapy, also known as CAR T, is one of the few types of immunotherapy. Each functions in different ways.

Doctors may turn to CAR T when T cells, which normally patrol the bloodstream to recognize germs and other invaders, fail to identify cancer as a foreign cell. This happens when the T cells lack specific proteins that bind to the tumor and attack it.

In CAR-T cell therapy, doctors first remove T cells from your body. They then add a gene that instructs the T cells to produce special proteins called CARs (chimeric antigen receptors) on their surface that can stick to cancer cells. After the CAR-T cells have multiplied in the lab, doctors reinfuse them into your body.

The modified T cells „were trained to recognize and kill tumor cells,“ says Dr. Renier Brentjens, Professor of Medicine and Director of the Cell Therapy Service at Memorial Sloan Kettering Cancer Center.

Furthermore, „the T cells multiply in the body by 1,000 to 10,000 times.“ And each of these cells can kill more cancer cells,“ says Porter.

Olson received three doses of CAR-T cells. After a few weeks, almost 20% of his white blood cells were CAR-T. When he returned to Porter for tests, „he told me they couldn’t find a single cancer cell in my body,“ Olson recalls.

The FDA approved the first CAR-T cell therapy in 2017. So far, the agency has approved two CAR-T cell therapies for cancer.

Axicabtagene ciloleucel (Yescarta). This is approved for adult B-cell lymphomas that have not responded to other treatments or have recurred after treatment.

Tisagenlecleucel (Kymriah). It has the same approval as Axicabtagene ciloleucel but can also be used to treat children and young adults with acute lymphoblastic leukemia.

In studies, 9 out of 10 people with acute lymphoblastic leukemia, whose cancer did not respond to other treatments or recurred, achieved complete remission with CAR-T cell therapy. Remission means that cancer cannot be detected in tests.

„It’s comparable to a severe flu,“ says Dr. Terry Fry, a cancer researcher and professor at Children’s Hospital Colorado.

Cytokines are proteins released by immune cells when attacking an infection. Symptoms include high fever, nausea, chills, headaches, rash, and breathing difficulties. CRS can be life-threatening but is treatable in a hospital.

CAR-T cell therapy can also affect the brain, causing confusion, difficulty speaking, and sometimes seizures. Typically, these symptoms occur within a few weeks after infusion and improve in about a month.

It’s been less than a decade since the first human received CAR-T cell therapy, so doctors are not yet aware of long-term risks.

CAR-T cell therapy works for blood cancers. But solid tumors like breast or lung cancer have not been successfully treated with it yet.

Leukemia and lymphoma cells are easier to detect because the target protein is on the surface and not on healthy cells.

„Solid tumors are harder to crack because it’s more challenging to distinguish between targeted proteins on cancerous tumors and those on healthy tissue,“ says Fry.

„I’m an optimist, so I would say we could have some CAR-T cells capable of attacking some solid tumors in the next five to ten years,“ he adds. „But there’s still a lot of work to do.“.“

Despite the challenges, CAR-T cell therapy has been a life-saving treatment for many who have received it. „A significant proportion of patients treated with these CAR-T cells will be long-term survivors. And the patients we treat are those whose survival prognosis was minimal to none,“ says Brentjens.

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