New Test Predicts Response to Cancer Treatment

A new test can indicate if a cancer patient is likely to respond to a common drug treatment and thereby help doctors target the drug for those patients who are likely to respond, according to the results of a clinical study. The study was reported in the November 9 issue of The New England Journal of Medicine.

The test detects whether the MGMT gene has a methyl molecule attached to it. The study showed that brain tumor patients who tested positive, meaning their MGMT genes were methylated, were 16 times more likely to respond to treatment with the most common form of chemotherapy, drugs called alkylating agents. They were also found less likely to die during the three years of follow-up than were those who tested negative. Alkylating drugs work by attaching to the genes in cancer cells, causing various changes that lead to the death of the cancer cell. If the MGMT gene has no methyl attached, it can switch on a repair process, thereby counteracting the effect of the alkylating drug, and the patient is unlikely to respond to treatment.

Of the 47 patients in the study, 40% tested positive for methylation of the MGMT gene. Of these, 64% showed either complete or partial response to alkylating agents compared with only 4% of those testing negative. The average time to tumor progression was 21.4 months for those with a positive test, compared to only eight months for those testing negative. The test is the product of Virco (Baltimore, MD, USA).The company is now developing a routine version of the test.

"This has the potential to be turned into a diagnostic tool that could help improve cancer therapy significantly,” said Steven Baylin, M.D., one of the main authors of the study and associate director for research at Johns Hopkins University (Baltimore, MD, USA).



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