Immune cells working as cancer assassins help with personalised treatment

13 June 2017
They doctors treating  Shefveland  embarked upon on a radical approach after standard treatment failed: they removed some of his immune cells, engineered them into cancer assassins and unleashed them into his bloodstream. Immune therapy, AP’s Lauran Neergaard writes, is the hottest trend in cancer care and this is its next frontier — creating "living drugs" that grow inside the body into an army that seeks and destroys tumors.

Shefveland is in full remission because of the experimental therapy. It marks an entirely new way to treat cancer — if scientists can make it work, and work safely. Early-stage studies do give hope as one-time infusions of supercharged immune cells help a remarkable number of patients with intractable leukemia or lymphoma.

Power of the immune system

Dr. David Maloney, Fred Hutch's medical director for cellular immunotherapy - who treated Shefveland with a type called CAR-T cells – says the immune therapy shows the unbelievable power of ‘your own immune system’.  "We're talking, really, patients who have no other options, and we're seeing tumors and leukemias disappear over weeks," added immunotherapy scientific director Dr. Stanley Riddell. But, "there's still lots to learn."

T cells are key immune system soldiers. But cancer can be hard for them to spot, whichs puts the brakes on an immune attack. Current immunotherapy drugs called ‘checkpoint inhibitors’release one brake so nearby T cells can strike. The new cellular immunotherapy approach aims to be more potent: give patients stronger T cells to begin with.

The first CAR-T cell therapies for a few blood cancers could hit the market later this year – right now they are available only in studies at major cancer centers. The Food and Drug Administration is evaluating one version developed by the University of Pennsylvania and licensed to Novartis, and another created by the National Cancer Institute and licensed to Kite Pharma.

Now scientists are tackling a tougher next step: making T cells target far more common cancers — solid tumors like lung, breast or brain cancer. Cancer kills about 600,000 Americans a year, including nearly 45,000 from leukemia and lymphoma. But there are still formidable challenges. For example, scientists still are unraveling why these living cancer drugs work for some people and not others.

Still in early stages

The research into the work of CAR-T cell therapie is, still in its early stages.  Small, early studies in the U.S. made headlines as 60 percent to 90 percent of patients trying CAR-Ts as a last resort for leukemia or lymphoma saw their cancer rapidly decrease or even become undetectable. Recently, Chinese researchers reported similar early findings as 33 of 35 patients with another blood cancer, multiple myeloma, reached some degree of remission within two months.   But too few people have been studied so far to know how long such responses will last. A recent review reported up to half of leukemia and lymphoma patients may relapse.

Also, doctors must learn to manage potentially life-threatening side effects from an overstimulated immune system. Concerning as well is a small number of deaths from brain swelling, an unexplained complication that forced another company, Juno Therapeutics, to halt development of one CAR-T in its pipeline.

CAR-Ts cause collateral damage, killing some healthy white blood cells, called B cells, along with cancerous ones because both harbor the same marker. Finding the right target to kill solid tumors but not healthy organ tissue will be even more complicated. And CARs aren't the only approach. Researchers also are trying to target markers inside tumor cells rather than on the surface, or even gene mutations that don't form in healthy tissue. Still, there is promise for a new big step in treating cancer.