HIV-I Confirmatory Urine Test Approval Completes First Urine-Only System

Calypte Biomedical's urine HIV-1 Western Blot confirmatory test, approved by FDA on June 1, is available immediately at a cost of $25-30 per test, according to the company.

The product is intended for samples "repeatedly reactive" with the Sentinel HIV-1 urine antibody screening test, which cleared FDA via product licensing application in August 1996 ("The Gray Sheet" Aug. 12, 1996, p. 3).

The screening test, which costs around $4, combined with the confirmatory test, comprise the first urine-only HIV-1 test system available, the company maintains.

Ease in administration as well as greater patient comfort and lower risk of accidental infection are among the advantages of the exclusively urine-based system being touted by Calypte, which hopes to capture a major share of the roughly 60 mil. HIV tests performed in the U.S. annually. The company estimates that 1-8 samples per 1,000 screened would be candidates for the confirmatory test.

Approved via PLA supplement, the confirmatory test will be marketed in the U.S. by Indianapolis-based Seradyn, Inc., which also markets the Sentinel. In addition to its 20-person direct sales force, Seradyn will also use a network of 25 distributors, the largest being Fischer CMS, to market the test in the U.S.

Both tests will be packaged individually as well as together. The Sentinel is available in cartons of 192 and 480 tests. For now, the confirmatory test will be packaged in 27-strip packs, but Seradyn says that larger quantities will be available on request.

Like the Sentinel, the confirmatory test is being manufactured by Cambridge Biotech, the holder of the PLA. Production to satisfy current demand is expected to be achieved in two to four weeks, Seradyn says. The company currently reports a backlog of orders.

Large reference labs like Lab Core, Quest and SmithKline Beecham have expressed interest in the test, Seradyn says. The company also hopes to capture the large hospital and institutional market.

"Many of the people seen in settings like STD clinics, prison and drug rehabilitation facilities, for example, are at high risk for HIV," says Seradyn VP-Sales and Marketing Tedd Mishkin. "Not only will the urine HIV test be more acceptable than blood to many of these people, but the ability to do additional testing such as drug screens on the same urine sample could really help these institutions control their testing costs."

Seradyn also markets the test internationally with the exception of the Far East, India and Australia, which are handled by the Japanese firm Otsuka Pharmaceuticals. Another potentially large market that has been awaiting FDA clearance of the product is Mexico, which now requires HIV testing prior to marriage, Seradyn says.

Results of clinical studies of the confirmatory test showed minimal false positive and false negative rates. Specificity of 100% was reported in 515 low-risk patients cross-tested with serum tests. To determine sensitivity, investigators tested 748 individuals known to be HIV-1 positive. In this group there were two false negatives, resulting in a 99.7% sensitivity for the test. Researchers attributed the two false negatives to the anti-retroviral drug therapy the two patients were receiving.

In addition to screening and confirmatory uses, use of urine-based testing along with serum testing in clinical trials led researchers to wonder whether HIV antibodies could be present in some tissue and not present in others.

"Finding the HIV-1 antibody in only one part of the body, as we did by testing both urine and blood, suggested to us that HIV infection may be compartmentalized," Calypte founder and Chief Science Officer Howard Urnovitz, PhD, said. The finding was reported by Harvard Medical School researcher Ann A. Kiessling at Beth Israel Deaconess Medical Center in Boston.

"Urine-positive, serum-negative individuals represent an important group of people who may have limited the virus infection to a few compartments in the body," Kiessling said. "Understanding the mechanism of compartmentalization is urgently needed in order to design fully effective antiviral treatment strategies."