One in four HIV patients is resistant to all three classes of HIV drug regimens -- One in nine has resistance that can escape detection
SITGES, SPAIN, June 13, 2000 -- Data presented by Virco at the 4th International Workshop on HIV Drug Resistance & Treatment Strategies demonstrates that 27.2% of 11,990 HIV patients being surveyed had HIV that was resistant to all three classes of HIV drugs currently available. The U.S. survey conducted in 1999 and based on the routine clinical practice of testing HIV samples for drug resistance, also found that 29.1% had resistance to two classes of drugs, and 21.9% were resistant to one, leaving only 21.8% sensitive to all three classes.
"These data are very sobering," says John Mellors, M.D. of the University of Pittsburgh Medical Center and Co-Chair of the workshop. "The results of this survey not only reveal the extent of the resistance problem -- a major cause of treatment failure -- but also underline the importance of resistance testing to support treatment decision-making in HIV clinical practice".
According to one result of the survey, the choice of an adequate resistance test may also be a critical factor in determining the accuracy of the results. The study reveals that many of the HIV patients may have a virus with a mutation in its genetic code that cannot be detected by most of the current resistance tests. The mutation -- a change at codon 333 in the reverse transcriptase gene that facilitates dual AZT/3TC resistance -- was found in 12.1 % of the HIV samples. Many of the current tests for HIV drug resistance do not cover this region of HIV's genetic code.
"These data show that this is a relatively common mutation and serves as an important reminder to physicians that resistance testing technologies have to change to keep pace with the evolving patterns of HIV drug resistance," said Dr. Mellors. "It is important that physicians and their patients have up-to-date resistance information and select resistance tests accordingly," added Dr Mellors.
The survey was conducted by Stuart Bloor and his colleagues from Virco's research centre in Cambridge, UK. Virco provides genotypic and phenotypic resistance testing services to an increasing number of physicians world wide as part of routine clinical practice and has also developed the world's largest database of resistance information with over 70.000 genotypes and phenotypes.
"We are keen to use our resistance in formation and expertise at a population level as well as for the use of the individual physician and patient," commented Bloor. "Our database can provide extremely useful information on the evolution of HIV resistance and highlight important issues for HIV management technologies and strategies."
Company background
Virco is a multinational biotechnology company with operating subsidiaries in the United States, Belgium, The United Kingdom and Ireland. It applies the most advanced technologies in molecular biology, automation, ultra high-throughput screening and electronic data processing to the diagnosis and management of HIV, other infectious diseases and cancer. Virco is the only company to provide both genotyping and phenotyping HIV drug resistance testing and believes it provides the most sophisticated and comprehensive portfolio of phenotyping and genotyping decision support tools for physicians treating HIV infected patients. Virco sells its testing services via Laboratory Corporation of America Holdings (LabCorp) as well as directly to HIV/AIDS centres in Europe, Canada, Japan and Australia. Virco has also recently announced a two-year agreement with Gilead for the promotion of Virco Resistance Monitoring Services to US HIV Prescribers by the Gilead sales force. For further in formation, please visit Virco's website: http://www.vircolab.com.
The workshop
The International Workshop on HIV Drug Resistance and Treatment strategies brings together 250 of the worlds top experts on HIV resistance for a four-day closed meeting each year. It is generally regarded as the most prestigious meeting on this subject.
Virco scientists and resistance monitoring technologies were involved in more than 30 of the 200 papers accepted for presentation at the meeting.