UPDATE 2-US panel wants test data on ChemGenex cancer drug

* Omapro designed for patients with genetic mutation

* Panel says genetic test should be cleared by FDA (Adds panel member, company comments)

By Lisa Richwine

GAITHERSBURG, Md., March 22 (Reuters) - A proposed leukemia drug from ChemGenex Pharmaceuticals CXS.AX should not be approved until the company shows a genetic test will accurately identify patients likely to benefit, a U.S. advisory panel said on Monday.

The Australian company is seeking Food and Drug Administration approval to sell the injectable drug Omapro in the United States for chronic myeloid leukemia patients with a specific genetic mutation.

In a 7-1 vote, an FDA advisory panel said the agency needed to require and review data on a "well-characterized" test for the mutation before considering approval of Omapro. ChemGenex used two different laboratory tests in a company study, but the tests are not FDA approved.

"I feel strongly if we don't have a good test ... how can we pick the right people?" said Virginia Mason, a registered nurse who served as the panel's consumer representative.

The agency usually follows panel recommendations when deciding whether to approve new medicines.

Omapro, or omacetaxine, is aimed at chronic myeloid leukemia (CML) patients who do not improve with Novartis AG's (NOVN.VX) Gleevec pill. CML is a type of cancer that originates in bone marrow, the spongy tissue that makes blood cells.

While Bristol-Myers Squibb Co's (BMY.N) Sprycel and Novartis's Tasigna also treat patients after unsuccessful Gleevec treatment, Omapro targets only those who test positive for a specific genetic mutation known as Bcr-Abl T315I.

The company has not submitted information about the test's performance to the FDA, which raised concerns about the possibility of inaccurate results, agency staff said.

With a false positive finding, "the patient may not receive more effective, less toxic therapy," said Dr. Richard Pazdur, head of the FDA's cancer drugs office.

ChemGenex Chief Medical Officer Adam Craig, speaking to reporters after the meeting, said the company has been working with the FDA to gain approval for a test. Asked how long that could take, Craig said "I suspect it would be months." The company has a meeting scheduled with FDA officials next month, he said.

ChemGenex plans to develop Omapro in Europe, the Middle East and parts of Africa under a deal with Hospira (HSP.N). (Reporting by Lisa Richwine; editing by Carol Bishopric)