Box 3. Infectious diseases driving the diagnostics bus

The infectious disease market and in vitro diagnostics (IVD) in general are expected to grow steadily (Fig. 4). The need for more rapid diagnosis and the emergence of resistance in big markets like HIV and HCV are fueling the development engine. While the big diagnostics companies—Roche, Abbott and Becton Dickinson—duke it out with competing HIV viral load assays along with the traditional infection assays, small biotechs are garnering some attention for their innovative contributions to viral diagnosis.

Such companies are already reaping rewards in the form of deals with large pharma. Earlier this year, Monogram Biosciences (S. San Francisco, CA), which has a cadre of HIV-related assays, had its longstanding relationship with Pfizer expanded to include its tropism assay, which Pfizer used during the development of its co-receptor antagonist Selzentry (maraviroc)—a deal estimated to be worth $25 million to the smaller company. Applying Monogram's Trofile assay in a pivotal phase 3 clinical trial to the selection of patients that expressed the CCR5 receptor on CD4⁺ T cells proved critical to the success of that trial. Patients expressing the CXCR4 receptor were considered unlikely to respond and hence were excluded from the trial. The FDA approved Selzentry for CCR5-positive HIV patients in August of this year; Monogram has since marketed the Trofile assay, which works by amplifying HIV RNA from patient samples, packaging it into particles and testing for infectivity on CCR5- and CXCR4-expressing cell lines.

Monogram reports alliances with a number of other pharmaceutical giants, including Merck, which reportedly used Monogram's PhenoSense assay in selecting a background antiretroviral treatment for testing its integrase inhibitor drug raltegravir. The Phenosense assay determines drug resistance in virus isolated from patients' blood.

Addressing a large market, HPV in women—made larger by the introduction of the HPV vaccine in 2006, which raised awareness of the issue—Digene (Gaithersburg, MD) has parlayed its hybrid capture test for the 13 subtypes of HPV associated with cervical cancer into a sweet acquisition deal. After enjoying several years of increasing sales since its first HPV diagnostic launch in 2000, the company was acquired (in July 2007) by the giant diagnostics Qiagen for $1.6 billion.

Some see the present situation with anti-virals as revolutionary. Bruce Patterson, a professor of pathology at Stanford Medical School and founder of the diagnostics company Invirion (Oak Brooke, IL), likens today's climate in virology to the way bacteriology flourished after the discovery of penicillin. Once there are therapies, it becomes necessary to identify the cause of a viral infection and to have ways of measuring drug susceptibility and resistance if it occurs, he points out. This is driving the growth rate and rate of change in viral diagnostics market, but even so, drug developers are out ahead of diagnostics. Invirion, which has a cell-based technology based on work from Patterson's laboratory, is working with companies early in development—it has a number of products going through phase 2 and phase 3 clinical trials—so that once a product is approved, the diagnostic will be in the ready

But the sector has its challenges. With new technologies come considerable barriers to adoption, as some newer techniques require expensive and difficult-to-operate instrumentation and are also likely to encounter physician resistance and lack of experience in applying tests appropriately and interpreting test results. Test developers have to tailor their products to the marketplace to achieve success. According to a 2006 Frost and Sullivan report, US Infectious Disease Diagnostics Market, this requires that US clinical laboratories develop "custom solutions" that take into account challenges such as testing volume, reimbursement rates in different locales and the focuses of physicians and clinical laboratories.

Laura Defrancesco