Engineered immune cells boost leukemia survival for some

Patients with low disease load had best outcomes in first long-term look

CAR-T cell attacking a leukemia cell

IMMUNE ATTACK  Doctors can engineer a patient’s own immune cells to kill cancer cells. These engineered cells, called CAR-T cells, were effective for some people against relapses of leukemia over the long term. Here, a CAR-T cell (red) attacks a leukemia cell (yellow).

Eye of Science/Science Source

WASHINGTON — Immune cells engineered to hunt and destroy cancer cells may help some people with acute lymphoblastic leukemia (ALL) live much longer.

Outcomes depended upon disease severity before treatment, oncologist Jae Park reported April 3 at the American Association for Cancer Research annual meeting.

In ALL — expected to strike 5,970 people and kill 1,440 in the United States in 2017 — immune cells called B cells grow out of control in bone marrow and can spread to other tissues. Overall, five-year survival rates are 71 percent. But fewer than 10 percent of people survive for five years after a relapse of the cancer, said Park of Memorial Sloan Kettering Cancer Center in New York City.

Park and colleagues genetically engineered T cells from 51 people whose leukemia came back or who didn’t respond to initial chemotherapy. These CAR-T cells seek out and kill the rogue B cells.

Of 20 people who started the study with leukemia cells making up less than 5 percent of their bone marrow, 95 percent had a complete response to the CAR-T treatment. Most are still alive with no signs of leukemia; one patient remains in remission five years after treatment.

But 31 people who started immune therapy with leukemia cells composing more than 5 percent of their bone marrow didn’t fare as well. After good initial responses, the cancer came back a median of 6.3 months later. Patients survived a median of 17 months, although some are still alive after three years.

The second group also tended to have more severe side effects, including an immune reaction called cytokine release syndrome and neurotoxicity, or nerve problems.

Park and his colleagues are not yet sure why the therapy works better for some people than others. But, he said, CAR-T cell therapy “still provides better survival than traditional treatments.”

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master’s degree in science journalism from Boston University.

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