DNA from Blood Shows Chemotherapy Response

A special test kit containing DNA isolated from blood, rather than from tissue samples, has shown the ability to predict the response to chemotherapy in patients with lung cancer.

The more invasive practice of obtaining a tumor biopsy from lung cancer patients has not enabled detection of low levels of specific mutations shed from tumors into blood. This is because of the high background of normal DNA. A paper published in the July 1, 2006, issue of Clinical Cancer Research indicates that DNA isolated from blood can be used to measure mutations in serum, which can predict the response to the drug gefitinib (Iressa).

The study was conducted by the National Cancer Center in Tokyo (Tokyo, Japan) using the DxS (Manchester, UK) epidermal growth factor receptor (EGFR) mutation test kit. The kit is a molecular assay combining allele-specific polymerase chain reaction (PCR) with an amplification refractory mutation system (arms) and Scorpions, a rapid fluorescing system.

In addition to heralding the introduction of blood-based detection, the authors of the paper concluded that patients who were EGFR-mutation-positive appeared to have better outcomes with gefitinib treatment in terms of progression-free survival, overall survival, and response, than those patients who were EGFR-mutation-negative.

The main author of the paper, Dr. Kazuto Nishio said, The DxS test kit detected mutations that were missed by direct-sequencing techniques. We anticipate that the detection of EFGR mutations in serum DNA using the Scorpion arms assay will be useful as a feasible approach for predicting tumor reponse to gefitinib.

DxS has already developed assays for the 26 most common EGFR mutations, which predict both drug response and drug resistance. Further oncology kits are being developed.



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