About The Study

This study compared AZT therapy alone vs AZT plus 3TC vs AZT plus 3TC plus loviride.

Study Approach

This was a double-blinded study (neither doctors nor volunteers knew which therapy volunteers received). Participants were randomly assigned to one of three treatment groups: existing AZT therapy only; AZT-based therapy plus 3TC (150 mg twice daily); or AZT-based therapy plus 3TC (150 mg twice daily) plus loviride (100 mg three times daily). The duration of treatment was 52 weeks and the primary endpoint of the study was progression to a new AIDS diagnosis or death.

Study population

One thousand, eight hundred and ninety-two volunteers in 14 countries participated, including over 200 people in 11 Canadian centres. Australian, European and South African sites were also major participants in the trial. CD4 counts were between 25 and 250. Characteristics at the beginning of the trial were well-matched across the three treatment groups. Median CD4 count was 131, and 62% entered the trial with AZT monotherapy as current treatment. The average age of participants was 36 years and 90% were males.


Both 3TC groups showed a significant survival benefit. Progression to new AIDS events or to death occurred in 17% of patients in the placebo group (those receiving only their existing AZT therapy); in nine percent of patients in the 3TC group; and in eight percent of those in the 3TC/loviride arm. Both disease progression and mortality were cut in half in the two 3TC trial groups, and there was no increase in grade three or four toxicities (severe side effects) in the two 3TC groups. CD4 counts and viral load levels measured in a subset of 332 patients showed benefit in the 3TC groups with significant changes from baseline and control. The addition of loviride did not result in additional clinical benefit over that seen with 3TC; however, the trial was not large enough to detect this.


Compared to AZT-based therapy alone, 3TC added to AZT-based regimens significantly reduced progression to AIDS or death and increased survival.