By LESLIE H. LANG UNC-CH School of Medicine
CHAPEL HILL, N.C. - AIDS investigators at the University of North Carolina at Chapel Hill are testing the first of a new class of drugs that attacks HIV before it enters the cell and may prove effective for patients with drug-resistant HIV.
The fusion inhibitor, known as T-20, prevents HIV from fusing with the cell surface membrane. Thus, T-20 attacks HIV in an entirely different way than the most potent HIV agents now in use.
"HIV resistant to the currently available medications would not be expected to be resistant to this drug because of its unique action," says Dr. Joseph Eron, associate professor of medicine at the UNC-CH School of Medicine.
On Feb. 4, Eron will present detailed findings of the study at the Sixth Conference on Retroviruses and Opportunistic Infections in Chicago.
Eron is a principal investigator for this multi-center study begun in August and sponsored by Durham-based Trimeris, Inc., maker of T-20. He says the results are impressive, "particularly when one considers the population that enrolled in this clinical trial is extremely difficult to treat."
The infectious disease specialist notes that the average number of anti-HIV medications taken by the 78 HIV-infected patients prior to the Trimeris Phase II Clinical Trial was nine. None of the agents, including an average of three protease inhibitors per patient, had proven effective in these patients over the long-term. Additionally daunting was the patients' very high average baseline viral load - the concentration of HIV particles per milliliter of blood. But according to Eron, patients in the new trial taking higher T-20 doses showed up to 90 percent reductions in viral load without major side effects.
In the trial, T-20 was given for 28 days either by continuous subcutaneous infusion or simply by injecting it subcutaneously (much like insulin is administered in diabetes). T-20 was also given either as part of an anti-retroviral drug "cocktail" or as the sole drug.
Eron says the new results definitively show that injection can be an alternative to infusion. Targeted blood levels of T-20 were achieved both through infusion and with twice-daily injections.
"This finding is important because twice-daily injection is far more convenient for patients than a continuous subcutaneous infusion pump," Eron explains.
"I think the study is extremely important because it is a clear demonstration of anti-retroviral effects with an agent that is completely novel, one that works by a different mechanism of action than currently available therapies," Eron says.
Results of this and subsequent T-20 investigations by Trimeris will be aimed at meeting rigorous Food and Drug Administration scrutiny to obtain approval for the drug.
"This particular trial was aimed at finding the correct dose and to show 'proof of principle' that the drug could be administered in a relatively convenient way," Eron says. "The trial lets me and others test a new drug on HIV patients who have failed lots of drugs and provides important information that will allow us to go on and study T-20 in combination with other HIV medications for longer durations."
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