Gilead Sciences has revealed that a preliminary 24 week analysis of a study comparing tenofovir/FTC/efavirenz to AZT/3TC/efavirenz shows a significant advantage to the tenofovir/FTC arm, with a higher proportion of patients in this arm achieving and maintaining a viral load below 400 copies/ml at week 24. The results are likely to give a major impetus to the marketing of a new pill containing tenofovir and FTC, called Truvada, that was approved in the United States on August 2nd.
The results come from a planned interim analysis of Gilead’s Study 934, a Phase III open-label 48-week clinical trial that has enrolled 517 HIV-infected treatment-naive patients in the United States and Europe. Participants in one arm of the study receive tenofovir (Viread) 300mg, FTC (Emtriva) 200mg and efavirenz (Sustiva) 600mg, all dosed once daily. Patients in the comparator arm receive AZT/3TC (Combivir) twice daily and efavirenz 600mg once daily.
The interim analysis shows 88% of patients in the tenofovir/FTC arm compared to 80% of patients in the Combivir arm achieved and maintained HIV RNA below 400 copies/ml at week 24 (p = 0.019; 95% confidence interval [CI], 0.8% - 13.3%). Close attention is likely to be paid to the wide confidence interval when these results are presented at scientific conferences later this year and clinicians will also be eager to see the results of a comparison of patients with viral load below 50 copies/ml, the gold standard for any regimen. Information on the baseline characteristics of the two treatment groups, including any factors that might bias the results in favour of one group, will also need to be examined.
In the analysis used in this study, any patient whose viral load was suppressed below 400 copies/ml who subsequently experienced a viral load blip above this level before resuppression of viral load would be counted as a treatment failure.
Three percent of patients in the tenofovir/FTC arm compared to 9% of patients in the Combivir arm discontinued from study regimens due to adverse events (p = 0.013). The incidence of grade 3 or 4 clinical adverse events was 9% in the tenofovir/FTC arm compared to 15% in the Combivir arm. Patients who switched from efavirenz due to intolerance were not counted as treatment failures.