The future of genetics and genomics

December 15, 2010

The promise of genomic discoveries is tremendous, but modern medicine is not yet ready to use the bulk of these discoveries, said Muin Khoury, MD, PhD, at the annual meeting of the American College of Clinical Pharmacology (ACCP) in Baltimore, Md.

The promise of genomic discoveries is tremendous, but modern medicine is not yet ready to use the bulk of these discoveries, said Muin Khoury, MD, PhD, at the annual meeting of the American College of Clinical Pharmacology (ACCP) in Baltimore, Md.

“We’ve made tremendous progress in the past 10 years, but we are not there yet. Yes, the technology is cheaper, we can map whole genome sequences, and people have tried to put this to use in their clinics. But it will take a few more years before we get there,” said Dr. Khoury, founder and director of the National Office of Public Health Genomics, of the Centers for Disease Control and Prevention (CDC), Atlanta, Ga.

Not there yet

Genetics and genomics are wonderful tools for scientific discovery, but are they currently useful tools for clinical practice?

At present there are many genetic tests on the market, Dr. Khoury said, but they are mainly for rare genetic diseases. “Their pharmacogenetic applications are up-and-coming, but they are not there yet.”

According to Dr. Khoury, genetics is no different from other areas of medical research and should be subject to the same standards of evidence and protection applied to other areas of medicine.

“We need to protect genetic information as well; it is sensitive information that has the potential to be misused. Genetic information requires the same level of protection from ethical and legal perspectives. But we should also subject it to the same standards of evidence in evidence-based testing,” he said.

Moving forward

How can genomics be translated from the bench to the bedside?

“The challenge the medical community faces now is finding the balance between premature translation and inappropriate cost utilization. The potential of these new technologies must be defined, or premature and inappropriate use will have to be dealt with,” said Dr. Khoury.

One example of premature use of information is personal genomic testing, aimed mainly at the public so far. A number of companies provide genomic findings to individuals, yet the accuracy and even utility of these tests in clinical practice have yet to be determined and proved.

The BRCA example

To illustrate how long it takes genetic discovery to travel from “bench to bedside,” Dr. Khoury cited the example of the BRCA1 gene mutation. The strong association between this gene mutation and an increased risk for breast cancer was discovered in 1994, but it took the U.S. Preventive Service Task Force until 2005 to recommend gene testing for BRCA1 and 2 in women whose family incidence of these gene mutations is high, said Dr. Khoury.

“The incidence of BRCA1 testing is even spotty right now,” he said. “In addition, relatively few insurers will cover the costs of such testing. This is something that was discovered in 1994, and this example shows how long it takes to go through that pipeline from discovery to implementation.”

HER2 and trastuzumab

Another example Dr. Khoury cited was the discovery of the association between the expression of HER2 in breast cancer and the success of trastuzumab (Herceptin) therapy.

In the 1980s, it was discovered that 20% to 40% of women with breast cancer overexpressed HER2. HER2 overexpression may predict tamoxifen failure and different rates of response to chemotherapeutic agents such as the taxanes and anthracyclines. Clinical data showed that outcomes were much better when trastuzumab was used in women with an overexpression of the HER2 gene.

The detection of HER2 and its overexpression is performed using fluorescent in situ hybridization (FISH) and/or immunohistochemistry (IHC).

“This is one example of a genetic-testing success story,” Dr. Khoury said.

Stakeholder agreement

Another issue to be dealt with concerns the various stakeholders in the medical community: academics and business people, federal and state policymakers, and payors.

“We need the right balance here. Can we get the stakeholders together and speaking the same language about genomics? This is very hard to do, but I am trying,” said Dr. Khoury.

In 2005, Dr. Khoury established a collaborative initiative at the CDC known as Evaluation of Genomic Applications in Practice and Prevention (EGAPP). EGAPP is an independent panel comprising multidisciplinary experts who examine the clinical literature and determine the validity of genetic tests for any given use. They are currently funding several comparative research initiatives.

“Can we have genomic medicine that still subscribes to the principles of evidence-based medicine? I think we can. For common disease states, we should be able to compare whether the outcomes will be different if we use pharmacogenomics versus not,” Dr. Khoury said.