Darunavir efficacy is promising at 48 weeks
Darunavir (Prezista), a new protease inhibitor for HIV patients (PJ, 10 March, p273), has shown promising results in phase II trials comparing it with control protease inhibitors in treatment-experienced patients
(Lancet 2007;369:1169).
The ongoing POWER 1 and 2 studies aim to evaluate the efficacy and safety
of darunavir in combination with low-dose ritonavir. In this pooled analysis
at 48 weeks, the researchers compare patients randomised to receive darunavir-ritonavir
(600/100mg twice daily) and those receiving an individually optimised
protease inhibitor-based regimen (control PIs); all patients receive
an optimised background regimen (two or more nucleoside reverse transcriptase
inhibitors, with or without enfuvirtide).
At week 48, the response rate (10-fold drop in HIV RNA) for the darunavir-ritonavir
patients was 61 per cent compared with 15 per cent for control PI patients
(difference 46 per cent, 95 per cent confidence interval 35–57;
P<0.0001). The proportion of patients with viral load less than 50
copies/ml was greater in the darunavir-ritonavir group than in the control
PI group (45 per cent versus 10 per cent; P<0.0001). Increases in
CD4 count were also greater in the darunavir-ritonavir group at 102 cells/µl
compared with 19 cells per µl in the control PI group (P<0.0001).
The darunavir-ritonavir combination was not associated with any new safety
concerns during the 48-week analysis, say the researchers.
The author of an accompanying comment (ibid, p1143) points out that clinical
endpoint data need to be obtained, ideally at two to three years or later.
He adds that the darunavir-ritonavir regimen also needs to be compared
with tipranavir-ritonavir. However, he concludes that, for now, those
treating patients “will probably rejoice in the availability of
darunavir, since it seems to be a safe, well-tolerated and truly effective
agent against multidrug-resistant HIV”.
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