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Research using T-cells may help in treatment of Leukaemia and related blood cancers
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Emma Whitehead has been bounding around the house, practising somersaults and rugby-style tumbles that make her parents wince. It is hard to believe, but last spring Emma, then 6, was near death from leukaemia. She had relapsed twice after chemotherapy, and doctors had run out of options. Desperate to save her, her parents sought an experimental treatment at The Children’s Hospital of Philadelphia, US, one that had never before been tried in a child or in anyone with the type of leukaemia Emma had. The experiment, in April, used a disabled form of the acquired immune deficiency syndrome (AIDS) virus to reprogramme Emma’s immune system genetically to kill cancer cells.
The treatment nearly killed her. But she emerged from it cancer-free and seven months later is still in complete remission. She is the first child and one of the first humans ever on whom new techniques have achieved a long-sought goal—giving a patient’s own immune system the lasting ability to fight cancer.
Emma had been ill with acute lymphoblastic leukaemia since 2010, when she was 5, her parents, Kari and Tom, say. She is their only child. She is among just a dozen patients with advanced leukaemia to have received the experimental treatment, which was developed at the University of Pennsylvania. Similar approaches are being tried at other centres, including the National Cancer Institute and Memorial Sloan-Kettering Cancer Center in New York.
“Our goal is to have a cure, but we can’t say that word," says Dr Carl June, who leads the research team at the University of Pennsylvania. He hopes the new treatment will replace bone-marrow transplantation, an even more risky and expensive procedure that is now the last hope when other treatments fail in leukaemia and related diseases.
Three adults with chronic leukaemia treated at the University of Pennsylvania have also had complete remissions, with no signs of disease; two of them have been well for more than two years, says Dr David Porter. Four adults improved but did not have full remissions, and one was treated too recently to evaluate. A child improved and then relapsed. In two adults, the treatment did not work at all.
Despite the mixed results, cancer experts not involved with the research say it has tremendous promise, because even in this early phase of testing it has worked in seemingly hopeless cases.
Hervé Hoppenot, president of Novartis Oncology, Greater New York City Area, says the research has the potential—if the early results hold up—to revolutionize the treatment of leukaemia and related blood cancers.
To perform the treatment, doctors remove millions of the patient’s T-cells—a type of white blood cell—and insert new genes that enable the T-cells to kill cancer cells. The new genes programme the T-cells to attack B-cells, a normal part of the immune system that turns malignant in leukaemia.
The altered T-cells—called chimeric antigen receptor cells—are then dripped back into the patient’s veins, and if all goes well they multiply and start destroying the cancer. The T-cells home in on a protein called CD-19, found on the surface of most B-cells, whether they are healthy or malignant.
A sign that the treatment is working is that the patient becomes terribly ill, with raging fevers and chills—a reaction that oncologists call “shake and bake", Dr June says. Its medical name is cytokine-release syndrome, or cytokine storm, referring to the natural chemicals that pour out of cells in the immune system as they are being activated, causing fevers and other symptoms.
Dr Michel Sadelain, who conducts similar studies at the Sloan-Kettering Institute, says: “These T-cells are living drugs. With a pill, you take it, it’s eliminated from your body, and you have to take it again." “But T-cells," he says, “could potentially be given only once, maybe only once or twice or three times."
The research is still in its early stages, and many questions remain. The researchers are not entirely sure why the treatment works, or why it sometimes fails.
©2012/The New York Times
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