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Eviplera works well regardless of viral load or CD4 count, may improve lipid levels
Liz Highleyman, 2013-10-11 16:30:00
The single-tablet regimen Eviplera (rilpivirine/tenofovir/emtricitabine) worked as well as Atripla (efavirenz/tenofovir/emtricitabine) for treatment-naive people across a range of viral load and CD4 T-cell levels, researchers reported at the Second IDWeek conference last week in San Francisco. Another study found that switching from a boosted protease inhibitor to Eviplera lowered cholesterol and triglyceride levels
Calvin Cohen from the Community Research Initiative of New England reported findings from the open-label STaR trial, the first head-to-head comparison of Eviplera vs Atripla in people starting antiretroviral therapy (ART) for the first time.
Unlike the earlier ECHO and THRIVE trials, which compared the same drug combinations taken as separate pills plus placebos -- requiring multiple daily pills with different food requirements -- all participants in STaR took a single tablet once-daily.
The study included 786 participants. More than 90% were men, about two-thirds were white, one-quarter were black and the median age was 36 years. At baseline the mean CD4 count was approximately 390 cells/mm3. Two-thirds started treatment with a viral load at or below 100,000 copies/ml, about 27% had 100,000 to 500,000 copies/ml and about 7% had above 500,000 copies/ml at baseline.
Overall, both single-tablet regimens produced good virological suppression: 86% of participants in the Eviplera arm and 82% in the Atripla arm achieved undetectable viral load (<50 copies/ml) at 48 weeks in a 'snapshot' analysis. Virological failure occurred in 8% and 6%, respectively, and CD4 gains were similar (200 vs 191 cells/mm3).
Cohen reported results from a sub-analysis looking at response rates according to baseline viral load and CD4 count. Amongst people with 100,000 copies/ml or less at baseline, 89% taking Eviplera and 82% taking Atripla had undetectable viral load at week 48, a statistically significant difference. Amongst those with viral load above 100,000 copies/ml, response was lower overall but similar for the two regimens, 80% vs 82%, respectively.
A similar pattern emerged for CD4 counts. Amongst people with greater than 200 cells/mm3, response rates were 88% for Eviplera and 83% for Atripla. Response rates were lower overall for people who started treatment with 200 cells/mm3 or less but similar for the two regimens, 72% and 71%, respectively. These differences were not significant.
Turning to adherence as determined by pill counts, people with 95% or better adherence had high response rates with either Eviplera or Atripla: 90% and 88%, respectively. Response rates dropped amongst people with less than 95% adherence, to 75% and 66%, respectively. But neither difference between the two regimens was significant.
Looking at these factors together, in an analysis that excluded patients with missing data, virological response rates were statistically similar amongst Eviplera and Atripla recipients with all combinations of baseline viral load, CD4 count and adherence levels. Amongst people with the least favourable combination -- high viral load, low CD4 count and sub-optimal adherence -- only 50% achieved viral suppression with either single-tablet regimen.
Turning to virological failure, rilpivirine appeared to fare a bit more poorly, especially amongst people with low CD4 counts. In the lower viral load/lower CD4, strata, two out of ten people (20%) with excellent adherence and three out of nine (33%) with lower adherence experienced virological failure on Eviplera, compared with none (0%) on Atripla. However, patterns were not consistent and the number of failing patients was small and affected by missing data, so differences were not significant.
People with at least 95% adherence reported better tolerability of both regimens. In particular, highly adherent patients taking Atriplareported fewer efavirenz-associated central nervous system side effects such as abnormal dreams or depression, but this study could not determine the direction of cause and effect. Although rilpivirine has been associated with fewer CNS adverse events than efavirenz in clinical trials, this sub-group analysis showed that in people with CD4 counts above 200 and greater than 95% adherence, the difference in tolerability was much less pronounced.
People with at least 95% adherence reported better tolerability. In particular, highly adherent patients taking Atripla reported fewer efavirenz-associated central nervous system side-effects such as abnormal dreams or depression, but this study could not determine the direction of cause and effect.
Cohen noted that this analysis was intended in part to see if rilpivirine is more vulnerable than efavirenz to resistance and treatment failure if patients miss doses. The findings indicated that although "both drugs suffered from missed doses," rilpivirine did not appear to do worse.
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