CTN 161: Simplified Protease Inhibitor Trial (SPRINT)

About the Study

This trial set out to evaluate the antiviral effect, tolerability, safety and pharmacokinetics of simplified dosing of two combinations of protease inhibitor (PI) therapy. Participants were assigned to take a once daily saquinavir Soft Gel Capsle (SGC) plus ritonavir combination, or a twice daily indinavir plus ritonavir combination. The two study arms were compared with respect to proportions of participants with viral loads below 50 and changes in CD4 counts after 24 weeks of treatment.

Study Approach

This was an open-label, randomized international study with a target enrollment of 150 volunteers with viral loads above 5,000 copies/ml. Participants were randomized to receive either 1,600 mg saquinavir SGC plus 100 mg ritonavir once daily (SQV/r), or 800mg indinavir plus 100 mg ritonavir twice daily (IDV/r), with two reverse transcriptase inhibitors (RTIs), or one nucleoside reverse transcriptase inhibitor plus one non-nucleoside reverse transcriptase inhibitor, as selected by their physicians. Eligible volunteers had never been on a regimen containing protease inhibitors, or had discontinued PIs without viral rebound.

Population

A total of 164 participants were enrolled in this study a clinical sites across Canada (72), Argentina (51) and the United States (41). The study analysis was then restricted to 147 eligible and participants who could be fully evaluated. Baseline characteristics were similar in both treatment groups: 70% were male, median age was 40, 90% had never taken PIs, 20% were injection drug users and the median viral load was 5.0 log10 copies.

Results

PI discontinuations or changes in PIs were considered failures. At 24 weeks, 51% of participants in the SQV/r group and 42% in the IDV/r group had viral loads below 50. The proportion of PI discontinuations or changes in PIs due to adverse events before 24 weeks was 10% in the SQV/r group and 26% in the IDV/r. Proportions of participants still on treatment at week 24 who had viral loads below 50 were 60% for the SQV/r group and 57% for IDV/r group. Median changes in CD4 cells were 134 and 120 respectively.

Conclusion

A once-daily regimen of saquinavir SGV/ritonavir with two RTIs is as effective as a twice-daily regimen of indinavir/ritonavir with two RTIs in suppressing viral load at 24 weeks in patients with PI-susceptible HIV virus. However, a higher rate of discontinuation for adverse events was observed among participants taking indinavir/ritonavir.

Note: These results are taken from an abstract presented at the XVth International AIDS Conference in Bangkok in July 2004.