By Randall Osborne
Calypte Biomedical Corp. won FDA approval of a confirmatory urine test for HIVinfection, giving the company the second half of a package for which it has waited twoyears.
The HIV-1 Western Blot test, developed with Cambridge Biotech Corp. and its parentcompany, bioMerieux Vitek Inc., of St. Louis, confirms the presence of antibodies to HIVin samples that are repeatedly reactive in Calypte's HIV-1 urine antibody screening test,approved in 1996 but used only in modest quantities.
A full HIV blood test by other makers already is on the market. Calypte's is the first thatworks the same way, but with urine.
"The starting gun goes off now," said Bill Boeger, CEO of Berkeley, Calif.-based Calypte,adding that marketing will begin as soon as possible. An inventory of the screen and theconfirmation tests, manufactured by Rockville, Md.-based Cambridge Biotech, already hasbeen built.
Cost for the screening test will range from $1 in overseas markets to as high as $3 in theU.S., Boeger told BioWorld Today.
"The real advantage is not so much in the cost of the test," he said. "The huge differencecomes in the cost of [sample] collection." Eventually, Calypte will seek approval for anover-the-counter version of the urine test.
"I'm guessing that's probably a year away," Boeger said.
Easier and less expensive than the blood test, the urine diagnostic exposes patients to lessrisk. Health-care workers, who might otherwise worry about accidental needle sticks, alsoare protected.
Patients often avoid screening because of their dislike of needles. The urine test avoidsthat problem, too.
Test Produces 100 Percent Specificity
Calypte verified the specificity of the test by conducting trials on a low-risk population, inwhich blood and urine samples were tested and results compared. Specificity was 100percent.
To determine sensitivity of the test, Calypte conducted clinical trials with people known tobe HIV-positive by blood test. Again, serum and urine were tested and results compared.Sensitivity was 99.7 percent (746 of 748 patients).
The two samples that turned up urine-negative were from blood-positive patients who hadAIDS and were undergoing anti-retroviral therapy.
In a second study of 391 high-risk patients of unknown HIV status, 17 showed positive byurine and serum tests. But, in three samples, the urine test was positive and the blood testnegative or uncertain.
Such outcomes lead Calypte to suggest the confirmatory test might be used not only as asupplement to the urine screen, but as a supplement to the blood test as well.
The urine test also has a lower frequency of indeterminate results than the blood test.Package inserts from two HIV-1 Western Blot blood test makers say indeterminate resultsfor low-risk people range from 11 percent to 37 percent, but the urine Western Blotresults showed only 0.2 percent (1 out of 515) indeterminate results in a low-riskpopulation.
"When the blood test was approved, there was nothing to compare it against," Boegersaid. "The gold standard finally has a rather rigorous test."
Approval of the confirmatory urine test took two years because of additional trialsrequired by the FDA, which, "in its wisdom, wanted to look at a number ofsubpopulations before they let this be a stand-alone test," Boeger told BioWorldToday. "They made us jump through a lot of hoops."
In previous use, positive results in repeated urine screens for HIV had to be confirmed bya blood test.
"That defeated the purpose," Boeger said. "It was like telling Nike, 'You can sell the shoefor the right foot but not the left.'"
Calypte, founded in 1988, will develop urine tests for chlamydia and H. pylori, aswell as "rapid" HIV tests, now that the second part of the urine test has been approved.
"This has taken so long, we've shepherded our cash," Boeger said.
As of March 31, Calypte had $8.4 million in cash, with a net loss for the quarter of $1.6million. The company's stock (NASDAQ:CALY) closed Monday at $6.093, down $0.281.*