Bristol-Myers Squibb reports encouraging results from HIV study

The difference between treatment arms may have been related to the 16% discontinuation rate in the Reyataz/r arm and the 21% discontinuation rate in the lopinavir/r arm, the company said.

The international, multi-center, open-label, 96-week Castle study randomized 883 treatment-naive patients infected with HIV-1. Approximately 440 patients were randomized to receive Reyataz 300mg and ritonavir 100mg (Reyataz/r) once daily and 443 patients were randomized to receive lopinavir 400mg and ritonavir 100mg (lopinavir/r) twice daily, each in combination with a once-daily, fixed-dose combination of emtricitabine 200mg/tenofovir disoproxil fumarate 300mg.

All patients had a baseline viral load of greater than or equal to 5,000 copies/ml; there was no CD4+ cell count restriction for study entry. The primary endpoint for the study was the proportion of patients with viral load less than 50 copies/m at 48 weeks.

The Castle results demonstrated the non-inferiority of Reyataz/r once daily versus lopinavir/r twice daily, each as part of HIV combination therapy in previously untreated HIV-1 infected adult patients. A number of secondary endpoints were also measured with regard to efficacy, resistance, safety, tolerability, and lipid effects.

The Reyataz/r arm was associated with significantly lower increases from baseline compared to the lopinavir/r arm in total cholesterol, non-HDL cholesterol, and triglycerides at 96 weeks (p<0.0001). Approximately 2% of patients in the Reyataz/r arm and 9% of patients in the lopinavir/r arm required initiation of lipid-lowering therapy while on study. Safety events in this study were consistent with prior experience. No new or unexpected safety events were identified.