Wednesday, November 27, 2013

Cancer Meets its Nemesis in Reprogrammed Blood Cells

"The results are holding up very nicely." Cancer researcher Michel Sadelain is admirably understated about the success of a treatment developed in his lab at the Memorial Sloan-Kettering Cancer Center in New York.

In March, he announced that five people with a type of blood cancer called acute lymphoblastic leukaemia (ALL) were in remission following treatment with genetically engineered immune cells from their own blood. One person's tumours disappeared in just eight days.

Sadelain has now told New Scientist that a further 11 people have been treated, almost all of them with the same outcome. Several trials for other cancers are also showing promise.

What has changed is that researchers are finding ways to train the body's own immune system to kill cancer cells. Until now, the most common methods of attacking cancer use drugs or radiation, which have major side effects and are blunt instruments to say the least.

The latest techniques involve genetically engineering immune T-cells to target and kill cancer cells, while leaving healthy cells relatively unscathed.

T-cells normally travel around the body clearing sickly or infected cells. Cancer cells can sometimes escape their attention by activating receptors on their surface that tell T-cells not to attack. ALL affects another type of immune cell, the B-cells, so Sadelain takes T-cells from people with ALL and modifies them to recognise CD19, a surface protein on all B-cells – whether cancerous or healthy. After being injected back into the patient, the reprogrammed T-cells destroy all B-cells in the person's body. This means they need bone marrow transplants afterwards to rebuild their immune systems. But because ALL affects only B-cells, the therapy guarantees that all the cancerous cells are destroyed.

by Andy Coghlan, New Scientist | Read more:
Image: Steve Gscheissner/Science Photo Library