Developing Resistance to Gleevec

[Guest guest]

CHICAGO (Reuters) - " Leukemia patients may be able to avoid developing

resistance to the drug Gleevec through a mathematical formula that predicts when

they should receive an immune-boosting vaccine, researchers said on Thursday.

The approach, which marries math and medicine, may help extend the effectiveness

of the drug and may even help cure some patients, they said.

" The hope really is to get patients off Gleevec ultimately, " said Dr. Lee

of Stanford University School of Medicine, a leukemia specialist who worked on

the study. It's very very early days, but that is the hope. Gleevec, or

imatinib, a once-a-day pill made by Novartis, transformed treatment of chronic

myelogenous leukemia, or CML, because it is effective and easy to use. Before

its introduction in 2001, the five-year survival rate was 50 percent. That has

jumped to 95 percent. But patients must stay on the drug indefinitely, and the

fear is that they may develop resistance to it, Lee said.

" The idea behind the new approach is to get the body's own immune system to take

over the fight against the cancer, said Doron Levy, a mathematician at the

University of land, whose study appears in Public Library Journal of Science

journal PLoS Computational Biology. The researchers developed a mathematical

model based on immune responses of people with CML who were taking Gleevec for

four years. " We saw it has a certain profile if you look at it over time, " Levy

said in a telephone interview.

" When first diagnosed, the immune system of CML patients is low, but as they

begin to respond to treatment, the immune system strengthens and starts to fight

off the cancer. As the drug continues to attack cancers cells, however, the

body's immune response falls. That is the ideal point for introducing a cancer

vaccine, Levy said. Using their model and information gathered from patients'

blood, Levy and colleagues think they can develop a personalized method of

predicting when patients might get the most benefit from a vaccine.

" What you can try to do is to boost the immune response when it needs it he

most, " he said. " The timing is the crucial issue. The vaccine the researchers

propose is an injection of the patient's own blood taken when they are first

diagnosed, but purged of any cancer cells. " You basically take the blood of the

patient and introduce it back after you kill everything in it, " Levy said.

" He said the body recognizes these dead cells as foreign invaders, and starts to

rev up the immune system. Levy said patients would need monthly blood tests to

monitor their immune systems and determine when the time is right for vaccine.

So far, the research is based on work on patients' blood in the lab and on

mathematical simulations, Levy said. But the progress has been enough to win a

five-year grant from the National Cancer Institute to continue studying the

approach. CML is relatively rare. In the United States, it strikes about 4,600

people a year. " ***************

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FYI,

Lottie