'CAR-T cells can cure patients with leukemia', according to a decade long study

Source: Axios

Ten years after receiving a treatment that modifies a patient's own immune cells to attack cancer, two patients who had a form of blood cancer show no signs of the disease, researchers report.

Why it matters

The patients' remissions hint at how long the effects of CAR-T therapy — a promising but currently very costly treatment— may persist in some people.

“We can now conclude CAR-T cells can cure patients with leukemia based on these results," Carl June, an immunologist and oncologist at the University of Pennsylvania and an author of the paper published in Nature, said in a press briefing last week.

"We need many more patients to be followed but at least in these two patients there is no more leukemia."

How it works

CAR-T therapy involves collecting a patient's T cells — a type of immune cell — from their blood, modifying the cells so they have a receptor that targets and then destroys cancer cells, growing the T cells and infusing them back into a patient's blood.

CAR-T therapies have been approved by the FDA to treat several types of leukemia and lymphoma, as well as multiple myeloma.

It's also being studied in clinical trials for the treatment of a range of other cancers.

The therapies have shown promise but can come with risks, including developing cytokine release syndrome and neurological effects.

What they found

Three patients with chronic lymphocytic leukemia (CLL) — a slow-progressing cancer that starts in the bone marrow and goes to the blood — received a CAR-T therapy in 2010 at the University of Pennsylvania as part of a clinical trial assessing the safety and effectiveness of the treatment.

Two patients went into complete remission that year.

The researchers analyzed the patient's CAR-T cells over time and found that 10 years later the cells continued to be active and surveilling for cancer cells, and no leukemia cells were detected, June said.

The cells also evolved in the patients as normal T cells do: They went from active killer T cells to another type of immune cells called helper T cells that are bystanders but were still able to kill cancer cells.

How the remission is maintained is difficult to study, the researchers said. They can't determine if every cancer cell is gone or if they are "coming up like whack-a-moles and keep getting killed by the cells," June said.

"Clinically he is cured because 10 years down the line there is no leukemia."

Keep in mind

The therapy doesn't work for all patients or all types of cancers.

The new study provides details about how the CAR-T cells work and could help to improve the therapy to be effective in more people.

"The deep learning built into these trials is key. That will bring us to the next step," said J. Joseph Melenhorst, an immunologist at the University of Pennsylvania and another author of the study.

What's next

"The big scientific challenge is how to make it work in solid cancers," June said.

The majority of cancers produce solid tumors surrounded by proteins and cells that CAR-T cells struggle to penetrate.