Scott Hammer presented data from ACTG 364, a "rollover" study from an earlier NIH trial. This is a Phase II, randomized, trial designed for nucleoside reverse transcriptase inhibitor (NRTI) experienced patients. There were three treatment arms comparing nelfinavir (NFV) and/or efavirenz (EFZ) in combination with two nucleoside analogs. This important study points the way to effective regimens (so-called "salvage regimens") even for patients who have been heavily pre-treated. Each patient with a viral load above 500 copies was assigned to Treatment Group A and received, in an open-label fashion at least 1, and if possible 2, new NRTIs. Each patient was then randomized, in a double-blind fashion, to one of three possible arms featuring either NFV and/or EFZ, as follows:

The possible dual NRTI combinations were ddI/d4T, ddI/3TC, or d4T/3TC.

Subjects with viral loads below 500 copies were assigned to Treatment Group B and remained on their originally assigned ACTG 302/303 dual nucleoside analog therapy. A total of 195 patients were in Treatment Group A, while 41 people were in Treatment Group B. The patients' baseline median viral load was 7776 copies and mean CD4 (T-cell) count was 389 cells. Of the 195 patients on Treatment Group A, 66 were on the NFV+NRTIs arm, 65 were on the EFZ+NRTIs arm, and 64 were on the NFV+EFZ+NRTIs arm.

A total of 33 patients, or 17%, discontinued study participation during the 52 week follow-up period. The majority of the dropouts were due to treatment failure: 20 (61%) of the 33 patients (61%) had their viral load rise above 2,000, and one patient developed lymphoma. Additionally, 2 patients died while on study. One death was attributed to respiratory failure (this death occurred in the NFV arm at week 40) and the other death was a result of pancreatitis and multi-organ failure. This was reported in the EFZ arm at week 28.

Overall, 106 of 189 patients (56%) across all treatment arms at week 40-48 enjoyed viral load decreases by weeks 40-48, with the individual regimen breakdown as follows:

This result was highly statistically significant, with the NFV+EFV arm providing the most powerful anti-HIV activity, even in this highly experienced population. With regard to T-cell count increases, there were no significant differences among the three treatment arms at week 40-48, with patients enjoying a median increase of 94 cells.