Monogram launches Trofile HIV co-receptor tropism test

On 6 August 2007, South San Francisco-based Monogram Biosciences announced the launch of its latest HIV diagnostic test, the “Trofile” co-receptor tropism assay.

This coincided with the US FDA decision to approve the CCR5 inhibitor maraviroc (see above), which requires a screening tropism test to determine whether a patients has R5-tropic virus.

The Trofile test determines which co-receptor a person’s HIV uses, and therefore whether maraviroc and similar drugs are likely to work for that individual. Trofile was used for patient selection for maraviroc clinical trials, and Pfizer and Monogram are collaborating to make the test available for use worldwide.

Trofile Assays have been performed on more than 23,000 samples in the company’s CLIA-certified laboratory. Trofile results are summarised in a report indicating the patient’s HIV tropism and are delivered to physicians in approximately 14 days.

Trofile is a patient selection co-receptor tropism assay that determines which co-receptor a patient’s HIV strain or strains use for viral entry – CCR5, CXCR4, or a combination of CCR5 and CXCR4. Trofile amplifies a patient’s HIV genome from a blood sample to make HIV particles specific to that individual patient. The resultant HIV particles are then used to infect CCR5- and CXCR4-expressing cell lines. Once the virus infects the cell and undergoes its single round of replication, a reporter gene expresses its indicator gene (luciferase), giving a visible signal-thus identifying the patient’s viral tropism. Viral load must be at least 1000 copies/mL to determine a patient’s viral tropism.

Source: Press statement: Monogram announces commercial introduction of Trofile assay

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