PRNewswire - Thursday September 24, 1998

The data shows that after six months, 39.1% of the patients tracked with genotyping have undetectable levels of HIV, while only 9.5% of the SOC control group have undetectable viral levels. The data further shows a six-fold decrease in viral load in favor of therapy adapted to genotypic analysis.

"We are excited by these results and did not expect to see statistical significance with only 47 of the 108 patients at the six month time point," says John K. Stevens, CEO of Visible Genetics Inc. "This study is pivotal because it is the first prospective HIV genotyping trial to reach statistical significance. It strongly suggests that drug selection in HIV patients based on the virus's genotype may play a critical role in the treatment of AIDS. It is essential, however, that we complete the full six month data analysis before we draw final conclusions."

Research has shown that HIV, like many other infectious organisms, is a highly polymorphic (genetically variable) virus that constantly mutates within infected individuals. The virus is so variable that it is unlikely that HIV viruses isolated from any two patients will have the same DNA sequence. Because of this rapid mutation rate, drugs used to treat HIV, while often effective for a period of time, eventually lose efficacy to newly-resistant HIV mutants. Development of such resistant HIV strains frequently leads to the return of high virus levels in the patient. Experts and on-going research have demonstrated that by genotyping HIV, it may be possible to treat individual patients by selecting drugs to which the virus has not yet developed resistance, and thus keep the virus at low levels.

The study sponsored by Visible Genetics, known as the VIRADAPT trial, is a randomized, controlled clinical trial carried out at Centre Hospitalier Universitaire de Nice, under the direction of Professor Pierre Dellamonica, an infectious disease specialist. Three sites and five physicians are involved in the trial. An additional 61 patients still have to reach the six month analysis point before the study is completed. All 108 patients participating in the study have reached the three-month point, and 47 patients have reached the six-month point. All the patients entered the study with high HIV viral loads (average 4.7 log units), all had failed triple drug therapy at least once, and all were taking at least one protease inhibitor. The detailed interim results will be presented as an oral presentation at the 4th International Congress on Drug Therapy in HIV Infection, Glasgow, Scotland (November 8-12).

"If the early results of the VIRADAPT study are confirmed in the longer follow-up, then this would be an important step towards a future where genotyping will be a routine procedure in the treatment of HIV-infected patients," says Charles A.B. Boucher, M.D., Ph.D., Clinical Virologist at the University Hospital in Utrecht, a leading HIV research center in Europe.

Genotyping by Visible Genetics' OpenGene system and TruGene HIV kit provides rapid (under 24 hour), high-resolution read-out of the virus's DNA codes, irrespective of polymorphic variability. The process is cost-competitive compared to other genotyping methods and is highly accurate. The kit contains all the reagents and standards required to sequence the DNA from the protease and Reverse Transcriptase (RT) regions of the AIDS virus, making it possible to genotype these therapeutically critical regions of the virus. These regions are known to develop mutations that make the virus resistant to drugs. Over 140 different resistant mutations have been discovered within the protease and RT regions. Combinations of these mutations develop over time within an individual patient and eventually confer resistance to the over 100 combinations of drugs now commonly used to fight AIDS.

Visible Genetics Inc. manufactures and markets high performance automated DNA sequencing systems and complete diagnostic kits for the analysis of genes linked to disease. The Company's OpenGene system employs proprietary stratified DNA testing and single-tube, single-step sequencing methods to significantly reduce the time and cost involved in identifying clinically relevant genetic information. VGI is a leader in the emerging field of pharmacogenomics, which uses genetic information in the identification, analysis and treatment of medical conditions in order to improve patient care and reduce healthcare costs.

SOURCE: Visible Genetics Inc.
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