Test Designed to Screen Resistance to Cancer Drug

Researchers in Japan have designed a test to identify patients who are likely to be resistant to imatinib, the standard drug for treating leukemia or cancer of the blood cells.

Such a test is important as imatinib resistance occurs usually to relapse patients, who tend to deteriorate very rapidly if they are given the wrong treatment.

In a paper published in Clinical Cancer Research on Thursday, the scientists said they developed a test which will help doctors tell if a patient with chronic myeloid leukemia (CML) is resistant to imatinib.

Imatinib, known by the brand Gleevac, is sold by Novartis AG to treat CML and other cancers. It blocks the enzymes of cancer cells instead of killing all rapidly multiplying cells.

"Most patients are sensitive to imatinib when they are diagnosed with CML, but resistance can indeed be acquired during or after imatinib treatment," said Yusuke Ohba, an associate professor at Hokkaido University Graduate School of Medicine.

"Even in cases where resistance develops or becomes apparent gradually, the most critical issue is what to switch over to. If the patient is switched to another (treatment) to which he/she is also resistant, the treatment will just be a waste of time and detrimental to the patient's condition."

"With our test, we can identify the most suitable drug, dose and/or drug combination, enabling therapy to be tailor-made for each individual patient. I believe this approach will make CML care more accurate and effective," he said in an email reply to questions from Reuters.

New drugs being developed for treating CML claim to overcome imatinib resistance, but until now, it is difficult to tell who has that resistance.

Using this test developed by Ohba and his colleagues, blood samples are collected from patients and then cultured and tested to see if they are resistant to imatinib.

These tests should help doctors determine if the patient may require stronger doses, combination therapy, or other drugs, Ohba said.