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Quest Diagnostics Launches HIV-1 Coreceptor Tropism Test

Quest Diagnostics Incorporated announced that its HIV-1 Coreceptor Tropism Test is available for physicians. The test determines whether a patient with a history of HIV drug resistance will respond to the latest class of HIV antiretroviral therapies. The test provides physicians with timely information reporting the results in approximately half the time of the nearest competing test. With the information provided by HIV-1 Coreceptor Tropism Test physicians can quickly determine or change therapy based on how the HIV virus infects cells in the individual patient.

Diagnostic testing is at the center of personalized medicine, providing genetic insights necessary to understand which medicines are most likely to produce a favorable health outcome for the individual patient, said Jon R. Cohen, M.D., senior vice president and chief medical officer, Quest Diagnostics. Our new HIV tropism test will advance personalized medicine for HIV by helping physicians identify suitable patients for a particular therapy and ensure those who are not suitable do not lose precious treatment time potentially better spent on a different drug.

The strains of HIV bind to activate and infect cells promoting disease progression based on the type of coreceptor on the cell’s surface in the process HIV coreceptor tropism. The antiretroviral drugs help immune system to fight infection by targeting the tropism process involving one or both coreceptors, CCR5 or CXCR4, of CD4 cells. HIV-1 viral particles are called R5-tropic when they use CCR5 coreceptor, X4-tropic when they use CXCR4 and those using both are called dual-tropic. X4- and dual-tropic are found in up to half of patients with a history of drug resistance or those with advanced disease. The viruses typically emerge after years of infection. Testing tropism prior to the start of a CCR5 inhibitor, such as maraviroc is recommended by US Department of Health and Human Services. It is observed that three out of four people taking HIV drugs experience treatment failure which is linked to drug resistance.

CCR5 antagonist entry inhibitors have given physicians new options for treating thousands of patients with HIV who have shown resistance to earlier HIV therapies. Yet, they are only suitable for about half of these patients due to different ways the virus tries to infect cells, said Jay G. Wohlgemuth, M.D., vice president of Science and Innovation, Quest Diagnostics. With our new tropism test, we expect to report results within seven days of receiving a patient specimen, compared to the leading commercial HIV tropism test, which requires two weeks of processing time once a sample is received. Considering that tropism status can change in as little as a few weeks in patients with a history of HIV drug resistance, faster results potentially translate into earlier initiation of efficacious therapy.

Quest Diagnostics scientists presented results of a three-way study using samples from patients with histories of drug resistance at the XVIII International HIV Drug Resistance Workshop in Fort Meyers, Florida. It is demonstrated that Quest Diagnostics’s HIV-1 Coreceptor Tropism test is in 74 percent agreement with Trofile, a leading phenotypic tropism test from Monogram Biosciences, and 74 percent agreement with SensiTrop II, a genotypic tropism test previously available from Pathway Diagnostics. The SensiTrop II test was 73 percent in agreement with Trofile. The investigators of Quest Diagnostics concluded that the concordance between the two independently developed genotypic tropism tests was comparable to the concordance of each assay with the Trofile, and that the proportion of X4 viruses detected did not vary significantly by assay type.

The prior version of the SensiTrop test is offered by Quest Diagnostics through a license with Pathway Diagnostics before acquiring the company during the fourth quarter 2008. The novel molecular-based technology developed by Quest Diagnostics scientists is used in new HIV-1 Coreceptor test.

The Quest Diagnostics HIV laboratory testing services include HIV tropism testing, HIV diagnostic testing to monitoring HIV viral load, determining a viral genotype and testing for the HLA-B.