ATV+c or ATV+r With FTC/TDF: Effective Options for All Patients with HIV?

ATV+c or ATV+r With FTC/TDF: Effective Options for All Patients with HIV?
ATV+c or ATV+r With FTC/TDF: Effective Options for All Patients with HIV?

SAN DIEGO, CA—The combination of either atazanavir plus cobicistat (ATV+c) or atazanavir plus ritonavir (ATV+r) with emtricitabine/tenofovir disoproxil fumarate (FTC/TDF) is an effective treatment option for patients who are infected with HIV regardless of race, sex, and age, with high and similar virologic success rates, a Week 48 subgroup analysis of a randomized Phase 3 trial confirmed at IDWeek 2015.

These results were also observed in patients with baseline CD4 count ≤200 cells/mm3 or baseline viral load >100,000 copies/mL, noted study investigators.

“Virologic success was high and virologic failure was low, and both were similar between ATV+c and ATV+r groups at Week 48, regardless of race, age, and sex” reported Edwin DeJesus, MD, FACP, FIDSA, of Orlando Immunology Center in Orlando, Florida, and colleagues, and “support the combination of either ATV+c or ATV+r with FTC/TDF as effective treatment options” for patients infected with HIV. Results were consistent “across ranges of viral load and CD4 counts, including patients with a baseline CD4 count ≤200 cells/mm3 or baseline viral load ≥100,000 copies/mL.”

Virologic failure at Week 48 were 5.8% vs. 4.0% for ATV+c and ATV+r, respectively. Discontinuation due to toxicity was uncommon through Week 48 and “similar between regimens for all subgroups,” Dr. DeJesus reported.

Cobicistat itself has no antiretroviral activity, he explained, but instead has been shown to enhance ATV pharmacokinetics as effectively as ritonavir in both healthy volunteers and in adults infected with HIV.

Previously, results of the Phase 3 randomized, double-blind, active-controlled trial in treatment-naïve adults infected with HIV found that at Weeks 48 and 144, ATV+c was non-inferior to ATV+r, both in combination with FTC/TDF. . The overall Week 48 virologic success rates were 85.2% for ATV+c vs. 87.4% for ATV+r.

In addition, “both regimens achieved high rates of virologic success with comparable safety and tolerability,” Dr. Dejesus noted.

At IDWeek 2015, the investigators described subgroup analyses for Week 48 virologic response and treatment discontinuation, including analyses for race, gender, and age (<40, ≥40 years), baseline CD4 count (≤200, 201–350, >350 cells/mm3), and HIV-1 RNA viral loads(HIV-1 RNA  ≤100,000, >100,000 copies/mL). Virologic suppression was defined as viral load <50 copies/mL in the intent-to-treat population using the FDA snapshot algorithm.

The virologic success rates of the 692 patients randomly assigned to receive ATV+c or ATV+r are summarized in the Table.

Table 1: Virologic Success Rate by Subgroup


Subgroup

ATV+c (n=344)  ATV+r (n=348)
 

Baseline CD4 count (cells/mm3)

  ≤200

  201-350

  >350

88.3%

90.4%

80.6%
 

87.7%

90.5%

84,8%
 

Baseline VL (c/mL)

  <100,000

  ≥100,000 c/mL

 

84.4%

86.4%
 

88.3%

86.0%

Race

  White

  Black/African American

  Asian

  Other
 

85.4%

73.8%

97.7%

89.2%

 

88.8%

82.5%

86.5%

87.9%

Age

  <40 years

  ≥40 years
 

80.9%

91.9%
 

85.9%

89.5%
 

Sex

  Male

  Female

 

85.0%

86.0%
 

89.2%

78.7%

There were no significant differences in ATV+c vs. ATV+r odds ratios for virologic success on the FDA snapshot algorithm, overall or by subgroup.

Discontinuation due to adverse events occurred in 7.3% of the ATV+c group and 7.2% of the ATV+r group and did not significantly differ by regimen within each subgroup. A fixed-dose combination tablet of atazanavir plus cobicistat received U.S. Food and Drug Administration (FDA) approval on January 29, 2015.



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