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Abacavir + Lamivudine Fixed Dose Combination Tablet Once Daily Compared with Abacavir and Lamivudine Twice Daily in HIV-1-infected Subjects (ESS30008)
N Sosa*1, C Hill-Zabala2, E DeJesus3, G Herrera4, A Florance2, M Watson2, and M Shaefer2
1Social Security Hosp, Panama City, Panama; 2GlaxoSmithKline, Research Triangle Park, NC, USA; 3IDC Res Initiative, Altamonte Springs, FL, USA; and 4Hosp CIMA, San Jose, Costa Rica
Background: ESS30008
compared abacavir (ABC) twice daily and lamivudine (3TC) twice daily to ABC+3TC fixed dose
combination (Epzicom, EZC) daily, both in combination
with a protease inhibitor (PI) or non-nucleoside reverse transcriptase
inhibitor (NNRTI).
Methods: We enrolled 260 HIV-infected subjects who
received > 6 months ABC+3TC twice daily and a PI or NNRTI as initial
antiretroviral therapy (ART), had
HIV-1 RNA < 400 copies/mL for > 3 months, and
had CD4 > 50 cells/mm3 at entry. Subjects were randomized to
continue ABC+3TC twice daily (n = 130) or switch to EZC daily (n = 130) for 48
weeks, in combination with the initial PI or NNRTI. Randomization was
stratified by background ART (PI
or NNRTI). Adherence to randomized therapy was assessed by pill count.
Results: At baseline median time on ABC+3TC twice daily
was 22 months, median CD4 was 554 cells/mm3,
and median HIV RNA was < 50 copies/mL. The most
common third agent was efavirenz (62%), fosamprenavir+ritonavir (17%), and nelfinavir
(14%). Non-inferiority of EZC daily to ABC+3TC twice daily was established
based on the primary endpoint of proportion of subjects who did not meet virologic failure criteria (confirmed HIV RNA ≥1265 copies/mL) (90% CI: –3.3 to
6.5) (ITT M=F). Proportions with
HIV RNA < 50 at week 48 (ITT
M=F) were 81% and 82% for EZC daily and ABC+3TC twice daily, respectively. Virologic failure was rare (2% daily, 3% twice daily). CD4
counts were stable through week 48. The most common grade 2 to 4 adverse effects
were similar across groups and included:
nasopharyngitis, headache, upper respiratory
infection, depression, arthralgia, nausea. No
drug-related severe adverse effects or hypersensitivity reactions were reported.
Over 48 weeks, median adherence was 93% in both groups; however, a higher
proportion of the EZC daily group (38.6%) than the ABC+3TC twice daily (31.0%)
had ≥ 95% adherence to randomized treatment.
Conclusions: EZC daily was established as noninferior to ABC+3TC twice daily in a regimen containing either
a NNRTI or PI over 48 weeks. A dual nucleoside backbone of ABC and 3TC
administered daily or twice daily is effective, durable, and well-tolerated.
Keywords: HIV; durability; epzicom
