Date: Mon, 27 Sep 1999 11:19:23 -0700 From: Andrew Shih Subject: Study Shows Superiority of Phenotypic HIV Drug Resistance Testing Embargoed Until Monday, September 27, 1999 12 noon Pacific Time PHENOTYPIC HIV DRUG RESISTANCE TESTING SUPERIOR TO TREATMENT HISTORY IN PREDICTING SALVAGE THERAPY SUCCESS -- Late Breaker Study Presented Monday at ICAAC Uses Novel Phenotypic Assay, PhenoSense(TM) HIV -- SAN FRANCISCO -- A late breaker study presented today at the 39th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) by Dr. Michael Saag of the University of Alabama, Birmingham found that phenotypic HIV drug resistance testing is superior to treatment history in predicting sustained HIV suppression in antiretroviral therapy (ART) -experienced patients who are starting new treatment regimens. Today's presentation, "Predictive Value of HIV Phenotypic Susceptibility Testing in an HIV Clinical Cohort" (Late Breaker Session, Monday, Sept. 27, 12:00pm, Room 103/104), described the use of ViroLogic, Inc.'s novel phenotypic drug susceptibility assay, PhenoSense HIV. ViroLogic's rapid test directly measures the sensitivity or resistance of a patient's HIV to all available anti-HIV drugs. In the study, Dr. Saag and his colleagues followed 71 ART-experienced HIV patients with plasma viral loads of >5000 RNA copies/ml who were beginning a new salvage regimen. Plasma collected at baseline was tested retrospectively for phenotypic drug susceptibility. Patient data obtained included complete ART history. The data showed that a patient's phenotypic susceptibility profile, as measured by the PhenoSense HIV assay, best predicted sustained virologic suppression in these ART-experienced patients. Therapy history was less predictive of treatment success and did not provide additional predictive value when added to the phenotypic susceptibility information. These results suggest that phenotypic testing should supplement treatment history in selecting salvage regimens for patients. "Reduced drug susceptibility has become a significant roadblock to successfully treating people with HIV," noted lead investigator Dr. Michael Saag of the University of Alabama, Birmingham. "As we have shown, relying on a patient's treatment history alone to design salvage therapy regimens will be less predictive. Phenotypic susceptibility testing is clearly a useful tool which is superior to a thorough patient history as a predictor of salvage therapy success in heavily treated patients." About PhenoSense HIV and ViroLogic PhenoSense HIV directly measures the susceptibility of HIV to each of the currently available antiretroviral drugs, providing highly accurate, reproducible, and individualized drug susceptibility information in two weeks, rather than the nearly 4-6 weeks for other currently available phenotypic resistance tests. The substantial advantage in turnaround time, sensitivity and reproducibility provided by PhenoSense HIV makes phenotypic HIV resistance testing a practical tool for physicians. ViroLogic, a privately held South San Francisco-based biotechnology company, is a leader in the development of novel therapy guidance tools to enable patients, physicians and medical reimbursers to make rational treatment decisions in the management of viral diseases and cancer. The company's proprietary technology is also being used in the fields of viral pharmacogenomics to identify, analyze and select new drug candidates for treating viral diseases and cancer, and in disease management through the development of therapy guidance algorithms to guide patient therapy. Today's study, "Predictive Value of HIV Phenotypic Susceptibility Testing in an HIV Clinical Cohort," is one of seven studies utilizing the PhenoSense HIV assay presented at ICAAC. Contact: Sidney Ho, Director of Public Affairs (650) 635-1100 x206 sho@virologic.com # # #