Antiviral Potency of HAART Regimens and Clinical Success Are Not Strictly Coupled in Real Life Conditions: Evidence from the MASTER-1 Study

Abstract

Purpose: To compare in a real clinical setting the largely unknown midterm clinical effectiveness of two protease inhibitor (PI)-based highly active antiretroviral therapy (HAART) regimens with different potency and tolerability profiles in naïve patients. Method: This study was a multicenter, open-label, randomized trial in naïve patients with less than 400 CD4+ cell count/μL, regardless of viral load. Treatment arms were hard gel capsule saquinavir (HGC-SQV)-based HAART (Arm A), with an expected more favorable tolerability profile, and indinavir (IDV)-based HAART (Arm B), with more potent virologic activity. While viro-immunological surrogate markers and World Health Organization (WHO) grade III toxicity (secondary endpoints) were regularly monitored, primary endpoints of the study were clinical and defined as any AIDS-defining event, AIDS-related death, WHO grade IV toxicity, drop outs, and protocol violations. Results: 262 consecutive patients were enrolled in the study from March 1, 1997 to December 31, 1997, in 24 different Italian clinical centers (132, Arm A; 130, Arm B). After 24 months of follow-up, patients who were enrolled in Arm B showed a significantly higher rate of virological success (75% had viremia below 500 copies/mL, CI = 12.9%, in the on-treatment analysis) and immunological gain (mean CD4+ cell count increase of 274 CD4+ cells/μL, SD = 234) when compared to patients enrolled in arm A (57%, CI = 15.5% and 223 CD4+ cells/μL, SD = 192; p = .0353 and .026, respectively). Despite the significant difference observed in surrogate markers, the number of total primary endpoints did not differ in the two groups (55 out of 132 in Arm A vs. 58 out of 130 person-years in Arm B; p = .86). Conclusion: Our results suggest that, after 24 months of follow-up in a real clinical setting, a PI-based HAART induces significant clinical benefits in naïve patients even in the absence of a complete suppression of viral replication. However, the long-term clinical impact of the possible accumulation of viral mutations in the presence of low-grade viral replication remains to be elucidated.

Keywords:

• clinical endpoints
• HAART
• real clinical setting