Date: Thu, 23 Sep 1999 08:48:24 -0700 From: Andrew Shih Subject: Seven ViroLogic Studies to be Presented at ICAAC Embargoed Until Presentation (Times listed are Pacific) SEVEN STUDIES UTILIZING VIROLOGIC'S PHENOTYPIC HIV DRUG RESISTANCE ASSAY TO BE PRESENTED AT THE 39TH INTERSCIENCE CONFERENCE ON ANTIMICROBIAL AGENTS AND CHEMOTHERAPY (ICAAC) -Data Highlight Utility and Reliability of New Assay, PhenoSense™ HIV- SOUTH SAN FRANCISCO (September 23, 1999) - ViroLogic, Inc.'s novel phenotypic HIV drug resistance assay, PhenoSense™ HIV, will be the subject of seven studies to be presented at the 39th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in San Francisco, September 26-29. Included among research studies demonstrating the clinical applications of the assay will be a late-breaker presentation by University of Alabama, Birmingham researcher Michael S. Saag, MD, which addresses the correlation between the use of baseline phenotypic drug susceptibility testing and sustained viral suppression in antiretroviral-experienced patients on new treatment regimens. "We are proud that this newly available assay is already so well-represented in research presentations at this important conference," noted Dr. Nicholas Hellmann, Vice President of Clinical Research at ViroLogic. "These studies are part of the growing body of research demonstrating the scientific and clinical utility of PhenoSense HIV, its accuracy and sensitivity in measuring HIV drug susceptibility in individual patients, and its value as a research tool in the search for effective HIV therapies." Among the studies to be presented at ICAAC involving PhenoSense HIV are three oral and four poster presentations: Oral Presentations · "Predictive Value of HIV Phenotypic Susceptibility Testing in an HIV Clinical Cohort" (Late Breaker Session, Monday, Sept. 27, 12:00 p.m., Room 103/104) describes the research of Dr. Michael Saag of the University of Alabama, Birmingham, who examined the correlation between sustained viral suppression and baseline phenotypic drug susceptibility testing. In a cohort of antiretroviral therapy (ART) experienced patients starting a new ART regimen, phenotypic susceptibility to drugs in the new regimen was the best predictor of sustained virologic suppression. ART history was a less significant predictor of sustained virologic suppression than phenotypic susceptibility, suggesting a role for phenotypic testing in selecting salvage regimens for ART-experienced patients. · "The N88S Amino Acid Substitution in HIV-1 Protease…" (Abstract 1175, p. 496, Slide Session 116.1 "Resistance to Antiretroviral Drugs," Monday, Sept. 27, 2:00 p.m.) describes a study led by Dr. Neil Parkin of ViroLogic, which examined the N88S mutation to determine how it affects HIV's susceptibility to the recently approved protease inhibitor, amprenavir. Unexpectedly, the scientific team discovered that N88S increased resistance to the commonly prescribed antiretroviral drugs indinavir and nelfinavir, but also made the virus far more susceptible to amprenavir. Using the PhenoSense HIV assay, the researchers also identified several other mutations in HIV's genetic structure that influence the role of N88S in determining resistance. Because drug resistance is the result of a highly complex interaction of mutations, the scientists concluded that phenotypic testing was necessary to unravel the interplay of multiple mutations in determining drug resistance. · "Differences in Protease Inhibitor (PI) Phenotypic Susceptibility after Failure of the First PI-Containing Regimen" (Abstract 1167, p. 493, Slide Session 116.1 "Resistance to Antiretroviral Drugs," Monday, Sept. 27, 2:00 p.m.) describes the findings of a California Collaborative Treatment Group study led by Dr. Richard Haubrich of the University of California, San Diego. The study included patients who experienced treatment failure with commonly prescribed protease inhibitor combination therapies. Using PhenoSense HIV, the scientists searched for "cross-resistance," in which HIV from the patients developed resistance to multiple protease inhibitors despite treatment with only one of the drugs. The study found that, compared to all other protease inhibitors, nelfinavir was associated with less cross-resistance. Dr. Haubrich's study also examined the feasibility of using statistical modeling rather than phenotyping to predict emerging cross-resistance. However, the study found that the best statistical model misclassified 41% of patients with drug-sensitive virus. Thus, the model did not adequately predict phenotypic resistance. Poster Sessions · "Reproducibility of an HIV Phenotype Resistance Assay in Clinical Practice" (Abstract 417, p. 461, Poster Session 35.I "Antiretroviral Resistance and Resistance Testing," Sunday, Sept. 26, 1:30 p.m.) details a study from the California Collaborative Treatment Group led by Dr. Richard Haubrich of the University of California, San Diego demonstrating that the ViroLogic phenotypic assay provides consistent and reproducible results. · "Validation of the Performance Characteristics of a Novel, Rapid Phenotypic Drug Susceptibility Assay, PhenoSense HIV" (Abstract 418, p. 461, Poster Session 35.I "Antiretroviral Resistance and Resistance Testing," Sunday, Sept. 26, 1:30 p.m.), by ViroLogic researcher Dr. Nicholas Hellmann, demonstrates that PhenoSense HIV is a rapid (8-10 days) assay with greater sensitivity (500 copies/mL), accuracy, and reproducibility (<2.5 fold) than that offered by traditional HIV drug resistance assays. · "Retrospective Analysis of Baseline Susceptibility of Adefovir Dipivoxil (ADV)…" (Abstract 435, p. 467, Poster Session 35.I ""Antiretroviral Resistance and Resistance Testing," Sunday, Sept. 26, 1:30 p.m.) by a team led by Dr. Michael Miller of Gilead Sciences, employed PhenoSense HIV to examine patients' response to the experimental NRTI drug adefovir dipivoxil. The study found that the M184V mutation in HIV makes the virus highly susceptible to adefovir dipivoxil, while at the same time conferring resistance to 3TC. · "Complex Interactions Involving Multiple Amino Acid Substitutions Alter NNRTI Susceptibility" (Abstract 439, p. 468, Poster Session 35.I "Antiretroviral Resistance and Resistance Testing," Sunday, Sept. 26, 1:30 p.m.), led by Dr. Jeannette Whitcomb of ViroLogic, examines the role of multiple mutations in affecting resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs). The researchers found that cross-resistance among NNRTIs is extremely complex and difficult to measure using genotypic analysis, but that small to moderate changes in NNRTI susceptibility can be measured using the phenotypic assay, PhenoSense HIV. Other ViroLogic Activities at ICAAC ViroLogic is the proud sponsor of a Satellite Symposium at ICAAC, "Choosing the Path of Least Resistance: Viral Dynamics, HAART, and HIV Drug Resistance," which will be held on Sunday evening, September 26, immediately following the ICAAC Opening Session. The program will feature David Ho, M.D. of the Aaron Diamond AIDS Research Center, Victoria Johnson, M.D. of the University of Alabama, Birmingham, Douglas Richman, M.D. of the University of California, San Diego, Robert Schooley, M.D. of the University of Colorado, and Paul Volberding, M.D. of the University of California, San Francisco. ViroLogic representatives will be available during the conference to answer questions about HIV drug resistance and PhenoSense HIV at the ViroLogic booth in the ICAAC Exhibit Hall. About PhenoSense HIV and ViroLogic PhenoSense HIV rapidly and directly measures the sensitivity or resistance of a patient's virus to each of the currently available antiretroviral drugs for HIV, providing highly accurate, reproducible, 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. Contact: Sidney Ho, Director of Public Affairs (650) 635-1100, x206 sho@virologic.com # # #