ViroLogic Assays Used to Characterize and ID Potential Treatments for Virulent Multi-Drug Resistant Strain of HIV

02/14/05 -- ViroLogic, Inc. (Nasdaq: VLGC) today announced that the highly pathogenic isolate of HIV recently identified in a New York City resident was characterized at ViroLogic using its PhenoSense(TM), GeneSeq(TM), and Entry Assays to assess resistance to all currently available antiretroviral drugs. The isolate was sent to ViroLogic for more extensive testing after initial evaluation at the Aaron Diamond AIDS Research Center (ADARC) in New York suggested that the recently transmitted virus was resistant to three of the four classes of standard antiretroviral therapy. ViroLogic's analysis confirmed the data from ADARC, and importantly, revealed therapeutic options that informed the selection of a drug regimen for the patient.

Additional testing was performed using several newer assays developed at Virologic. The Entry Assay demonstrated that the virus was susceptible to enfuvirtide (Fuzeon(R)), the only commercially available entry inhibitor drug. The analysis at ViroLogic also identified the cellular receptors that this virus uses to enter CD4 cells, the targets of viral infection. The test results indicate that the virus uses a receptor that has been linked to accelerated immune destruction and rapid progression to clinical AIDS. Viruses with significant resistance often replicate less well than wild-type viruses. In this case however, the ViroLogic Replication Capacity (RC) assay indicated that virus replication was comparable to most wild-type strains. Replication Capacity is the focus of intensive study at ViroLogic and preliminary data indicate that viruses with high RC values are associated with more rapid immunosuppression.

"This episode serves as a sobering reminder of the potential danger of transmitted resistant viruses," said David D. Ho, M.D., Scientific Director and Chief Executive Officer of ADARC in New York and a Professor at The Rockefeller University. "This is an interesting case because it has features that we often see, although not typically in the same virus. While we see triple-class resistance fairly commonly in patients with a long history of antiretroviral drug experience, this case is noteworthy in that a single virus harbors triple-class resistance, a high RC, and CXCR4 receptor tropism in the setting of recent infection. The value of having access to comprehensive drug resistance testing technologies helped to clarify this patient's best treatment options."

"While the receptor tropism and RC of this virus suggest possible explanations for the rapid pace of disease progression in this patient, additional clinical tests regarding the individual patient's genetic make-up need to be conducted and are underway. Nonetheless, this appears to be a virus that is resistant to most antiretroviral drugs, replicates efficiently, and has led to the rapid onset of AIDS in this patient," continued Dr. Ho.

"This case reinforces the importance of resistance testing in the management of HIV patients, including those individuals who have not received prior antiretroviral treatment," said Michael Bates, M.D., Vice President of Clinical Research at ViroLogic. "At ViroLogic, we're focused on understanding how to use parameters like resistance, RC and tropism more effectively in patient management. We continue to define and broaden the clinical utility of ViroLogic's technology, improving the clinician's ability to optimize the management of antiretroviral therapy for their patients, and assisting our pharmaceutical colleagues in developing novel drugs to treat HIV infection."

ViroLogic's drug resistance test PhenoSense GT(TM) combines phenotypic and genotypic testing into one assay that is performed using a single patient sample, and is reported on a single form. This combination assay was developed to provide physicians with a more comprehensive look at an individual's drug susceptibility profile.

Understanding the clinical utility of Replication Capacity in the management of HIV-infected patients is currently the subject of a $1.5M grant awarded to ViroLogic by the National Institutes of Health. The Tropism Assay is currently being utilized in multiple pharmaceutical sponsored phase 2 and phase 3 clinical development programs designed to evaluate the efficacy and safety of inhibitors that block the ability of HIV to infect new cells.

About ViroLogic

ViroLogic is a biotechnology company advancing individualized medicine by discovering, developing and marketing innovative products to guide and improve treatment of serious infectious diseases and cancer. The Company's products are designed to help doctors optimize treatment regimens for their patients that lead to better outcomes and reduced costs. The Company's technology is also being used by numerous biopharmaceutical companies to develop new and improved antiviral therapeutics and vaccines as well as targeted cancer therapeutics. More information about the Company and its technology can be found on its web site at www.virologic.com.

Forward Looking Statements

Certain statements in this press release are forward-looking, including statements regarding operating results, the future role of ViroLogic's technology in the management of HIV-infected patients. These forward-looking statements are subject to risks and uncertainties and other factors, which may cause actual results to differ materially from the anticipated results or other expectations expressed in such forward-looking statements. These risks and uncertainties include, but are not limited to, risks and uncertainties relating to the performance of our products; our ability to successfully conduct clinical studies and the results obtained from those studies; whether larger confirmatory clinical studies will confirm the results of initial studies; our ability to establish reliable, high-volume operations at commercially reasonable costs; expected reliance on a few customers for the majority of our revenues; actual market acceptance of our products and adoption of our technological approach and products by pharmaceutical and biotechnology companies; our estimate of the size of our markets; our estimates of the levels of demand for our products; the timing and ultimate size of pharmaceutical company clinical trials; whether payors will authorize reimbursement for its products; whether the FDA or any other agency will decide to regulate ViroLogic's products or services; whether the Company will encounter problems or delays in automating its processes; whether intellectual property underlying the Company's PhenoSense technology is adequate; whether we may be deemed to infringe on the intellectual property of others and whether licenses to third party technology will be available; whether ViroLogic is able to build brand loyalty and expand revenues; and whether ViroLogic will be able to raise sufficient capital when required. For a discussion of other factors that may cause ViroLogic's actual events to differ from those projected, please refer to the Company's most recent annual report on Form 10-K and quarterly reports on Form 10-Q, as well as other subsequent filings with the Securities and Exchange Commission.

Source: ViroLogic, Inc.