Gene tests offer hope for cancer patients

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iol scitech aug 8 cancer cell

Reuters

Most cancer deaths are not caused by initial tumours, but by secondary tumours that are created by cancerous cells invading other parts of the body.

Chicago - A new way of evaluating tumours may soon help cancer patients identify the underlying genetic link to their disease - and the best possible treatment - all in a single test.

Researchers are set to begin clinical trials using a more comprehensive testing method that looks for all of the known genes that may be active in a tumour.

The new method could guide patients to the right drug earlier, potentially replacing current tests known as companion diagnostics that only look for a specific biological trait or “biomarker.” The presence of a biomarker can predict whether a new class of drugs called targeted therapies will work on particular tumours.

Results of these broader tests could even be used to quickly identify which patients might benefit from experimental drugs being tested in clinical trials. US health officials see it as the future direction of cancer diagnostics.

“We really are moving away from this one drug, one biomarker, one companion diagnostic,” said Dr Richard Pazdur, the US Food and Drug Administration's oncology chief.

In advanced melanoma, for example, about half of patients' tumours have a mutation in the BRAF gene. Roche makes a drug called Zelboraf that blocks that pathway, at least for a time. To get Roche's drug, patients need to be evaluated with an FDA-approved companion diagnostic test. One of the tests is also made by Roche.

In many cases, the FDA requires single-biomarker companion diagnostics as part of the drug approval process, but the broader testing model opens the door to additional players in the diagnostics space, including US-based Foundation Medicine Inc and Thermo Fisher's Life Technologies.

In a trial starting later this month, for example, patients with squamous cell carcinoma of the lung could be recommended for one of five experimental treatments based on which genes are active. Foundation Medicine's next-generation sequencing platform will be used to screen about 6 000 lung cancer patients over five years.

The Lung Master Protocol trial, also known as Lung-MAP, will take place in some 400 research centres. It is a public-private partnership between the National Cancer Institute, Amgen Inc , AstraZeneca Plc and its US-based biotech arm MedImmune, Roche's Genentech unit and Pfizer.

A similar effort called the National Lung Matrix trial being organised in Britain by AstraZeneca, Pfizer and Cancer Research UK is set to start taking patients in July or August. Pazdur said a conference this fall will also discuss plans for a trial in metastatic breast cancer.

“This is a new paradigm in many, many ways,” said Ellen Sigal, chairperson and founder of Friends of Cancer Research, which is organising the US lung cancer trial. “We're revolutionising not only the genetic testing but how patients get into a trial.”

 

ONE TISSUE, MANY TESTS

Dr Mace Rothenberg, senior vice president of clinical development for Pfizer's cancer business, said having a single test looking for a single biological marker made sense when there were only a few targeted cancer drugs, which exploit specific weaknesses in patients' tumours.

“In the past 10 years, we've now identified many more potential targets of drugs, and these molecules are involved in critical functions of a cancer cell,” he said. “Now it becomes very relevant that we be able to go beyond that one tissue, one test to one tissue, many tests.”

In non-small cell lung cancer, for example, there are more than a dozen different molecular abnormalities that are known to influence tumour growth.

Dr Vince Miller, Foundation Medicine's chief medical officer, said as more of the drugs win approval, doctors might need to run five to eight tests, all from a tiny scrap of tumour.

“Tissue scarcity was becoming a very real issue,” he said.

It's an issue that Dr. Tadd Lazarus, chief medical officer at Germany's Qiagen NV, knows about personally.

Lazarus' father is battling his second round of lung cancer, and biopsies must be done using a long needle, a process that produces only a tiny tissue sample. “You get a fixed amount of tissue and you have to maximize it,” he said.

The German diagnostics company has three companion diagnostic tests on the US market, including one recently approved for Amgen's colorectal cancer drug Vectibix.

Qiagen has also invested in a new testing platform from PrimeraDx, a privately held Boston-area company. Under an expanded partnership with Eli Lilly and Co, the companies plan to use the new platform to analyze both DNA and RNA biomarkers, targeting multiple molecular pathways active in common cancers.

Roche's Genentech is developing companion tests for about half of the experimental medicines in its pipeline, and is evaluating tests that can look at more than one target at a time, said spokeswoman Holli Dickson. - Reuters

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