Lilly, Amgen: data backs cancer drug use with normal gene

GAITHERSBURG, Md. (Reuters) - ImClone Systems and Amgen Inc told a U.S. advisory panel on Tuesday they have enough data from earlier studies to show their colon cancer drugs help those with a normal version of a certain gene.

Analyses of several trials for the drugs, ImClone's Erbitux and Amgen's Vectibix, found that patients with a normal version of a gene called K-ras benefited from treatment while those with a mutant version did not, the drugmakers told a U.S. Food and Drug Administration panel of outside experts.

"The data are ... nothing less than transformational," said Hagop Youssoufian, senior vice president of clinical research and development at ImClone, which was recently acquired by Eli Lilly and Co .

Both ImClone and Amgen are seeking FDA permission to tell doctors that patients with the mutant gene should not be treated with their respective drugs by including the trial findings on the products' labels.

About 60 percent of patients have tumors that express the normal K-ras gene, according to Bristol-Myers, which co-markets Erbitux in the United States. Merck KGaA sells it in other countries.

While marketing the drugs only for patients screened for normal versions of the K-ras genetic marker would curb their use, it would expand the field of personalized medicine in which certain treatments can be tailored for certain patients based on their genetic profile.

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Proponents of such medicine say it will curb costs by providing treatment only to those who will benefit and help those who won't improve avoid side effects, which can be particularly toxic with cancer therapies.

But the FDA, concerned about whether a retrospective look at earlier K-ras data is sufficient or whether more data needs to be collected, is seeking advice from its panelists over just how much evidence companies need to have when looking to target their therapies based on genetics.

Information from some early studies can help point to possible beneficial genetic makers that may guide a drug's development.

"However, it cannot directly address whether a particular biomarker test ... distinguishes patients who will or will not benefit from the drug," said Robert Becker, a diagnostic medical officer at the FDA's device division.

Analyzing data from earlier studies can lead to false conclusions or misinterpretation that could erroneously exclude patients who might benefit, FDA officials said. Genes can also have a wide expression, meaning it may be less clear whether patients have a normal version or not.

Tests that screen for a particular gene, including K-ras, also must be separately approved by the FDA. While some labs can screen for the gene, there are no approved K-ras tests, according to Amgen, which has said it is working with other companies to help develop them.

Amgen, like ImClone, said there was enough consistent evidence now to help doctors better use its drug. While the company is planning further studies, the information on K-ras emerged after many trials had already been set up.

"We recognize that, clearly, the science outpaced the studies," Paul Eisenberg, Amgen's senior vice president for global regulatory affairs.

The issue is growing, and FDA officials said they were looking for the panelists to address the overall issue of biomarker data, not just for Erbitux, also known generically as cetuximab, and Vectibix, known as panitumumab.

The FDA panel members were scheduled to discuss the issue later on Tuesday.

Genentech Inc has said its rival colon cancer drug Avastin works in patients with either type of K-ras.

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