Monday, December 10, 2012

Reprogramming T-Cells to Fight Cancer

Doctors from the Children's Hospital of Philadelphia have just reported the first clinical successes from a technique that has been talked about for years, reprogramming T-cells to kill cancerous cells:
It is hard to believe, but last spring Emma, then 6, was near death from leukemia. 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, one that had never before been tried in a child, or in anyone with the type of leukemia Emma had. The experiment, in April, used a disabled form of the virus that causes AIDS to reprogram Emma’s immune system genetically to kill cancer cells.

The treatment very nearly killed her. But she emerged from it cancer-free, and about seven months later is still in complete remission. She is the first child and one of the first humans ever in whom new techniques have achieved a long-sought goal — giving a patient’s own immune system the lasting ability to fight cancer. . . .

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 technique employs a disabled form of H.I.V. because it is very good at carrying genetic material into T-cells. The new genes program the T-cells to attack B-cells, a normal part of the immune system that turn malignant in leukemia.

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 that is found on the surface of most B-cells, whether they are healthy or malignant.
As always with experimental cancer treatments, it is very early to say if this will work on a large scale. But our growing prowess in manipulating genes opens up all sorts of new approaches to fighting disease, and over the next 20 years we may see many novel therapies along this general line. This approach is crude in that it attacks all B-cells, cancerous or not, leaving the patient's immune system weakened, possibly for life.

These doctors say the treatment costs $20,000 per patient, and that's only direct costs, since it is still an experiment and they aren't factoring in any overhead or the like. But even so it is much less costly than a bone marrow transplant, and the cost may fall over time as they get better at it.

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