Results from two studies show T-20 reduces HIV in treatment experienced patients over a one year period

Basel, February 19 - The body’s immune response can be improved and HIV viral levels reduced when the ground-breaking investigational HIV drug, T-20, is added to conventional powerful combination therapy "cocktails". These promising research results for the first in a new class of HIV drugs known as "fusion inhibitors" will be welcome news as Roche and Trimeris lead the way in the challenge to keep one step ahead of growing drug resistance. Unlike existing AIDS drugs, Fusion Inhibitors prevent HIV entering human cells.

Promising results are reported from two Phase II studies, one (T20-208) compared several formulations of T-20 in patients experienced with the three currently available classes of antiretrovirals (triple class experienced) and the other (T20-206) studied people who have taken just two of the existing classes (nucleoside reverse transcriptase inhibitors and protease inhibitors) but have not yet been exposed to non-nucleoside reverse transcriptase inhibitors (known as NNRTI naïve patients).

T20-208 assessed the antiviral activity, safety, tolerability, and pharmacokinetics of three T-20 formulations in treatment-experienced patients over a 48-week period. The patients entering this study had advanced disease with average blood levels of over half a million copies of HIV per mL and an average CD4 cell count of just 24 cells/mm³.

"After long term treatment (48 weeks) half (23 of 46) of the triple class experienced patients who used T-20 in combination therapy had their viral loads reduced beneath the limit of detection (<400 copies/mL). This is an impressive result for this growing and difficult to treat population," stated Dr. Joseph Wheat, Professor of Medicine, Indiana University School of Medicine, Division of Infectious Diseases. "We are also delighted to see that virtually all patients in the study (93% of 46 patients) completed a full year of treatment, indicating that long term treatment with T-20 administered subcutaneously twice daily is tolerable and acceptable to these patients."

In the other study, T20-206, among patients with exposure to only two classes of antiretroviral therapies, and earlier stage HIV disease, the addition of T-20 to a fixed highly active anti-retroviral (HAART) regimen enhanced virologic and immunologic response over the oral antiretroviral (ARV) regimen at 48 weeks.

The 48-week controlled study, T20-206, compared three doses of T-20 in combination with a regimen of oral antiretrovirals (containing abacavir, amprenavir, ritonavir and efavirenz) in 71 NNRTI naïve patients.

A comparison between the combined T-20 containing arms of the study versus the control arm highlighted that by the end of a year more than half (55%) of the patients taking drug regimens containing T-20 had their plasma viral load reduced to less than 400 copies per mL, whereas, 37% of the patients taking the control regimen succeeded in attaining this level of viral load reduction. Almost half (47%) of T-20-treated patients achieved viral loads reduced beneath the limit of detection (<50 copies/mL) compared to only 37% treated with the background regimen alone. CD4 cell counts were also higher in patients on T-20 containing regimens. This phase II study was not designed to show differences among treatment arms.

There was no increase in adverse events between those patients in the control arm and those patients receiving T-20. Approximately two-thirds of patients taking T-20 experienced local reaction at the site of injection but only three patients experienced sufficient discomfort to discontinue treatment.

"We are pleased to report that T-20 was shown to contribute to the activity of a conventional combination regimen and was an acceptable therapy to most patients over 48 weeks" said Dr. Jacob P. Lalezari, Director of Quest Clinical Research Institute, San Francisco. "As in previous studies, those receiving T-20 demonstrated enhanced virologic and immunologic responses above the oral ARV regimen alone, although this time in patients with less advanced disease and less previous antiretroviral drug experience".