Data Reported at ICAAC Indicates Selzentry Phase III Treatment-Naive Trial Shows Increased Efficacy When Used With Enhanced Trofile Assay

SOUTH SAN FRANCISCO, Calif., Oct. 26 /PRNewswire-FirstCall/ -- Monogram Biosciences, Inc. announced today that data presented this week demonstrated that in Pfizer Inc's phase III trial of Selzentry(TM) (maraviroc) in treatment naive individuals with CCR5-tropic HIV-1, increased efficacy was shown as a result of the enrichment of the patient population by use of the enhanced version of Monogram's Trofile(TM) Assay.

The data were reported this week at the 48th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) / 46th Annual Meeting of the Infectious Diseases Society of America (IDSA) in Washington DC.

Pfizer's HIV medication Selzentry (maraviroc) is approved for use in treatment-experienced individuals with R5-tropic HIV-1. In July 2007 Pfizer reported data from the phase III trial of Selzentry in treatment naive individuals ("MERIT"), in which patients had been selected for treatment by Monogram's Trofile Assay. The reported differences in outcome for individuals treated with Selzentry did not meet a predefined study endpoint of non-inferiority to an established first line treatment regimen. To week 48, 65% of individuals receiving Selzentry had HIV-1 RNA <50 copies/mL, compared to 69% of those individuals in the control arm of the trial.

In June 2008 Monogram introduced an enhanced sensitivity version of the Trofile Assay, with 30-fold greater sensitivity to detect low-level X4 HIV compared to the original assay. Monogram reassessed the original samples from the MERIT trial using the enhanced Trofile assay. These samples had been previously archived by Monogram and laboratory personnel had no knowledge of previous testing results or clinical outcomes data from the trial. The results obtained with the enhanced sensitivity version of the Trofile Assay were provided to Pfizer who conducted the clinical analysis in accordance with a prespecified statistical analysis plan.

Using the enhanced Trofile assay, 15% of MERIT screening samples previously defined as R5 HIV were reclassified as CXCR4-using (Dual/Mixed) HIV, and thus would have been unable to participate in the study. Analyses restricted to individuals with CCR5-tropic HIV as determined by the enhanced Trofile assay demonstrated an overall improvement in Selzentry efficacy relative to efavirenz (the control arm of the trial). In the new retrospective analysis of the MERIT trial samples, powered by the enhanced Trofile assay, 68% of individuals achieved HIV-1 RNA <50 copies/mL at week 48 in both the Selzentry and efavirenz arms of the study.

"The data presented this week demonstrate the value of selecting the appropriate individuals for Selzentry therapy," said William Young, Monogram CEO. "With proper patient selection, using Trofile, a positive response to therapy can be expected, even in early stage individuals where the standard of care is already very high. Monogram's commitment to scientific excellence is clearly reflected in the data presented this week, which provides increased hope for individuals infected with HIV that new classes of drug and new drugs, such as Selzentry, may benefit all HIV infected individuals, not just those individuals with advanced disease."

"Selzentry already has a proven record as a safe and effective therapeutic option for treatment-experienced HIV positive patients," said W. David Hardy, MD, Director, Division of Infectious Diseases at Cedars-Sinai Medical Center and Associate Professor of Medicine at the David Geffen School of Medicine at UCLA. "Improving our ability to select the best therapy for patients is critical. These new data enhance the confidence that physicians need when making treatment choices."

Conference Call

Monogram will host a conference call Monday, October 27 at 4:30 p.m. Eastern Time, in which Dr. David Hardy will review the clinical use of Selzentry and Trofile. This call will be in conjunction with Monogram's third quarter conference call. Dr. Hardy is Director, Division of Infectious Diseases at Cedars-Sinai Medical Center and is Associate Professor of Medicine at the David Geffen School of Medicine at UCLA. To participate in the live teleconference please call [phone], or [phone] for international callers, fifteen minutes before the conference begins. Live audio of the call will be simultaneously broadcast over the Internet and will be available to members of the news media, investors and the general public. Access to live and archived audio of the conference call will be available by following the appropriate links at http://www.monogrambio.com/ and clicking on the Investor Relations link. Following the live broadcast, a replay of the call will also be available at [phone], or [phone] for international callers. The replay passcode is 4461917. The information provided on the teleconference is only accurate at the time of the conference call, and Monogram assumes no obligation to provide updated information except as required by law.

About Trofile

Trofile is a clinically validated patient selection tropism assay that determines whether a patient is infected with a strain of HIV that uses either the CCR5 coreceptor, the CXCR4 coreceptor, or a combination of CCR5 and CXCR4 to enter cells. The use of CCR5, CXCR4 or both coreceptors defines the "tropism" of the virus strain. Trofile amplifies the envelope gene from a patient's HIV genome (from their blood sample) and then uses it to make HIV particles containing the patient's virus envelope protein. The resultant HIV particles are then used to infect cells that contain the CCR5 co-receptor or the CXCR4 co-receptor on the cell surface. Once the virus infects the cell, it undergoes a single round of replication. Virus replication results in the production of luciferase from a luciferase gene that is carried into the cell by the virus. The production of luciferase in either CCR5 cells, CXCR4 cells or both cell types defines the co-receptor tropism of the patient virus. Trofile is the only clinically validated tropism assay and has been used to select patients in all phase II and phase III studies of CCR5 antagonists to date.

In June 2008, optimization of Trofile made it substantially more sensitive at identifying very low levels of CXCR4 using virus (X4 or dual/mixed tropic) in HIV-1 patient samples while maintaining a high degree of accuracy. The assay can now detect X4 virus present at levels less than 0.3% of the total virus population, and at that level of X4 virus, the assay is 100% sensitive.

About Monogram Biosciences, Inc.

Monogram is 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 http://www.monogrambio.com/.

Forward-Looking Statements

Certain statements in this press release are forward-looking, including statements regarding the performance, demand and outlook for our products, including our Trofile and our projected revenues. 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 and acceptance of our products; the growth in revenues; the size, timing and success or failure of any clinical trials for CCR5 inhibitors, entry inhibitors or integrase inhibitors; our ability to establish reliable, high-volume operations at commercially reasonable costs; expected reliance on a few customers for the majority of our revenues; the annual renewal of certain customer agreements; 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 impact of competition; the timing and ultimate size of pharmaceutical company clinical trials; whether payers will authorize reimbursement for our products and services and the amount of such reimbursement that may be allowed; whether the FDA or any other agency will decide to further regulate our products or services, including Trofile; whether existing levels of reimbursement will be reviewed and reduced by third party payers, including Medicare; whether the draft guidance on Multivariate Index Assays issued by the FDA will be subsequently determined to apply to our current or planned products; whether we will encounter problems or delays in automating our processes; the ultimate validity and enforceability of our patent applications and patents; the possible infringement of the intellectual property of others; whether licenses to third party technology will be available; whether we are able to build brand loyalty and expand revenues; restrictions on the conduct of our business imposed by the Pfizer, G.E. and other debt agreements; potential Nasdaq proceedings to delist our common stock, our ability to regain compliance with Nasdaq listing requirements, the impact of a possible reverse split of the shares of our common stock, the impact of additional dilution if our convertible debt is converted to equity; and whether we will be able to raise sufficient capital in the future, if required. For a discussion of other factors that may cause actual events to differ from those projected, please refer to our 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. We do not undertake, and specifically disclaim any obligation, to revise any forward-looking statements to reflect the occurrence of anticipated or unanticipated events or circumstances after the date of such statements

Trofile is a trademark of Monogram Biosciences, Inc. Selzentry is a trademark of Pfizer Inc.

contacts: Alfred G. Merriweather Jeremiah Hall Chief Financial Officer Feinstein Kean Healthcare Tel: [phone] Tel: [phone]