New Gene Treatment Effective for Some Leukemia Patients

Denise Grady in The New York Times:

A new way of genetically altering a patient’s cells to fight cancer has helped desperately ill people with leukemia when every other treatment had failed, researchers reported on Monday in the journal Nature Medicine. The new approach, still experimental, could eventually be given by itself or, more likely, be used in combination treatments — analogous to antiviral “cocktails” for H.I.V. or multidrug regimens of chemotherapy for cancer — to increase the odds of shutting down the disease. Researchers say the treatment may be more promising as part of a combination than when given alone because, although some patients in the small study have had long-lasting remissions, many others had relapses. The research, conducted at the National Cancer Institute, is the latest advance in the fast-growing field of immunotherapy, which fires up the immune system to attack cancer. The new findings build on two similar treatments that were approved by the Food and Drug Administration this year: Kymriah, made by Novartis for leukemia; and Yescarta, by Kite Pharma for lymphoma.

In some cases, those two treatments have brought long and seemingly miraculous remissions to people who were expected to die. Kymriah and Yescarta require removing millions of each patient’s T-cells — disease-fighting white blood cells — and genetically engineering them to seek and destroy cancer cells. The T-cells are then dripped back into the patient, where they home in on protein molecules called CD19 found on malignant cells in most types of leukemia and lymphoma. The new treatment differs in a major way: the T-cells are programmed to attack a different target on malignant cells, CD22. Researchers have been eager to test this type of T-cell. One reason is that they hoped to find that CD19 was not the only vulnerable target, “not some kind of unicorn,” said Dr. Crystal L. Mackall, the senior author of the study and the associate director of the Stanford University School of Medicine’s cancer institute. Cancer cells are highly adaptable and often find ways to evade treatments aimed at only one target. “The idea that we could have one magic bullet is naïve,” she said. Another reason is that some patients with leukemia or lymphoma do not have CD19 on their cells, so the existing T-cell treatments do not work for them. Other patients, perhaps 30 percent or more, have CD19 at first and go into remission when treated, but then lose the protein and relapse within six months — a wrenching outcome for patients and their families, whose hopes soar and then crash. In theory, a treatment that goes after a different target could rescue patients who lack CD19 or lose it. An even more important reason for the interest in a new type of engineered T-cell is that it would enable scientists to develop combination immunotherapy that would attack cancer cells on different fronts at the same time — a proven key to success with chemotherapy.

More here.