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Good Long-Term Efficacy and Safety With Once-Daily Ritonavir-Boosted Saquinavir Plus 2 NRTIs: Presented at AIDS 2006

By Danny Kucharsky

TORONTO, CANADA -- August 18, 2006 -- Once-daily saquinavir/ritonavir- (SQV/r) based highly active antiretroviral therapy (HAART) shows excellent long-term antiviral efficacy and safety when used in treatment-naive patients, concludes a study presented here at the 16^th International AIDS Conference (AIDS 2006).

The study presented data for up to 144 weeks of therapy from the full Thai, treatment-naive population (n = 272) of the Staccato study, a randomized, collaborative trial of intermittent versus continuous HAART.

"Overall we see over 80% viral load undetectability after 3 years," said lead investigator Jintanat Ananworanich, MD, clinical trials coordinator, HIV Netherlands Australia Thailand Research Collaboration (HIV-NAT), Bangkok, Thailand.

The study began with 1,272 treatment-naive patients who entered an induction phase of at least 24 weeks with SQV/r and 2 nucleoside reverse transcriptase inhibitors (NRTIs) daily.

Patients with undetectable viral loads (HIV RNA < 50 copies/mL) and CD4 counts > 350 cells/mm³ were randomized to 1 of 3 treatment arms: 1) continuous treatment with their existing HAART regimen; 2) CD4-guided treatment interruptions, resuming HAART only when CD4 count fell below 350 cells/ mm³; 3) 1 week on, 1 week off therapy.

A preliminary analysis of the 1 week on, 1 week off therapy arm found an unacceptably high failure rate, leading to the termination of that arm.

Following a median of 94.9 weeks of treatment, all patients received 12 to 24 weeks of further therapy. "We used SQV/r 1600/100 mg once daily until 2005. With the new (film-coated) formulation we used 1500/100 mg -- 3 pills of saquinavir with ritonavir 100 once daily," Dr. Ananworanich said.

Of the 272 treatment-naive patients in Staccato, 261 completed at least 24 weeks of therapy, with a median follow-up time of 32 weeks (interquartile range: 24.0-89.2).

In the intent-to-treat analysis, 83.8% and 81.6% of patients in the 2 treatment arms, respectively, achieved HIV RNA levels of < 50 copies/mL following 24 weeks of treatment.

There were no new AIDS-defining illnesses but 4.8% of patients developed new Centers for Disease Control class B illnesses -- 4 cases of zoster, 2 oral candidiasis, 3 cases of thrombocytopenia without bleeding, and 4 pruritic papular eruptions.

There were 89 drug-related adverse events reported in 63 patients (23.2%), of which 77.5% were grade 1 in severity, 21.3% grade 2, and 1.1% grade 3. Diarrhea and nausea were the most common adverse events.

More than 81% of all treatment-naive patients achieved an undetectable viral load (< 50 HIV RNA copies/mL) following 24 weeks or more therapy with SQV/r and 2 NRTIs.

More than 90% of patients receiving continuous treatment maintained undetectable viral loads throughout the study (median follow-up 128 weeks). Continuous improvements in CD4 cell counts were also seen in this treatment arm. The overall median CD4 count increased from 422 cells/mm³ at randomization to 721 cells/mm³ after at least 144 weeks of treatment.

Dr. Ananworanich said data from the CD4-guided treatment interruption arm suggest such interruptions can provide a useful option if CD4 counts are maintained above 350 cells/ mm³; 85% of patients randomized to this arm subsequently achieved undetectable viral loads following after at least 12 weeks of treatment with the same regimen.

The study shows that in Thai patients, SQV/r 1500/100 mg or 1600/mg once-daily provides effective first-line therapy, she said. In Western patients, a once-daily regimen of SQV/r 2000/100 mg provides comparable exposure.

The regimen "worked very well in our population," Dr. Ananworanich noted during the presentation on August 16^th. "Our patients are very adherent to treatment." She added that lipid data was not shown in the study, but that no lipid increases were seen.

The study was supported by Roche, Gilead and Abbott.


[Presentation title: Long-term Efficacy and Safety of Once-Daily Ritonavir-Boosted Saquinavir Mesylate (SQV/r) Plus 2 NRTIs. Abstract WEPE0110]

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