Approximately equal numbers of patients with fewer than three TAMs and at least three TAMs were enrolled in the study. As well as M184V, the K65R mutation is associated with resistance to 3TC and the accessory mutations E44D and V118I may also affect 3TC susceptibility. No patient enrolled in the study had the K65R mutation at day 0 (two patients had K65R present on screening, but failed other screening criteria and so were not enrolled in the study). Most patients had neither the E44D nor V118I mutation at buy I-BET-762 day 0: one patient had an

E44E/D mixture, six patients had V118I or a V118V/I mixture and three patients had both E44D and V118I or a V118V/I mixture. All patients were receiving 3TC prior to screening and up to day 0; no patient was receiving FTC at screening. From day 0 to day 21, all but one patient were receiving two NRTIs (one of which was ATC or 3TC) (Table 2). The most common NRTI was zidovudine (32 patients in total), followed by abacavir (11 patients). Approximately 43% of patients were receiving a protease inhibitor (PI) and approximately 55% of patients were receiving a nonnucleoside reverse transcriptase inhibitor (NNRTI). The most common ZD1839 molecular weight PI and NNRTI were lopinavir (10 patients) and nevirapine (17 patients), respectively. There were two co-primary efficacy

endpoints in this study: the mean time-weighted average change in viral load from baseline to day 21 and the mean absolute change in viral load from baseline at day 21. The time-weighted average change in viral load from baseline to day 21 for the D21 PP population is shown in Figure 3. The effect of ATC on viral load was apparent at day SPTLC1 7 in both the 600 and 800 mg dose groups and the viral load continued to decrease to day 21 in both groups. The reductions in viral load at day 21 in the 600 and 800 mg ATC groups were statistically significant compared with the 3TC group, which showed little change in viral load to day 21 (Fig. 3). For the mean absolute change in viral load from baseline

at day 21, there were mean decreases in viral load of 0.90 and 0.71 log10 HIV-1 RNA copies/mL in the 600 and 800 mg ATC groups, respectively, compared with the mean decrease of 0.03 log10 copies/mL in the 150 mg 3TC group (P=0.006 and P=0.053, respectively, compared with the 3TC arm). The 600 mg dose produced slightly greater reductions in viral load over the 21 days compared with the 800 mg dose. This was not statistically significant and may reflect the fact that slightly more patients in the 600 mg arm had virus with the highest susceptibility to ATC: at baseline, 10 out of 17 patients in the 600 mg arm had virus with a <2-fold change in the IC50 for ATC to wild type, compared to six out of 16 patients in the 800 mg arm (data not shown). Five patients (29.4%) in the 600 mg ATC group and two patients (11.