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CLINICAL EFFICACY OF SALVAGE REGIMENS CONTAINING BOTH AMPRENAVIR (APV) AND
LOPINAVIR/RITONAVIR (LPV/r) AS COMPARED TO SALVAGE REGIMENS CONTAINING ONLY
LPV/r STRATIFIED BY NNRTI-EXPERIENCE
M Loutfy, C Thompson, M Trpeski, C Kovacs, A Rachlis, J Goodhew,
G Rubin, K Gough, S Walmsley
University of Toronto, Toronto, Ontario
Objective: To compare responses between patients with VL failure treated
with salvage therapy containing LPV/r and APV vs. LPV/r alone.
Method: Patients enrolled in the LPV/r EAP with at least 1M F/U were
analyzed in 2 groups: those receiving APV (600-1200 mg BID) plus LPV/r or LPV/r
as sole PI. The analysis compared the proportion achieving VL <50 c/mL and CD4
count change stratified by NNRTI-experience. Effect of APV dose on VL response
was evaluated.
Results: 96 patients initiated APV and LPV/r and 141 initiated LPV/r
as sole PI. 20.4% and 51.0% were NNRTI-naïve, respectively (p<0.01). The mean
duration of F/U was 5.7M. The dual-PI group was diagnosed with HIV for longer
(p<0.01) and had more previous ARVs (p<0.01). The baseline VL was 4.61 log in
the dual-PI group and 4.39 log in the LPV/r only group (p=0.12). In the NNRTI-experienced
strata, 22.0% (N=50) of the dual-PI group achieved VL<50/mL at 4-6 M vs. 32.6%
(N=46) of the LPV/r group (p=0.24). In the NNRTI-naïve strata, similar results
were found (50.0% vs. 76.5%; p=0.10). The baseline CD4 count was 170.2 c/mL
in the dual-PI group and 195 c/mL in the LPV/r group
(p=0.25). There was no difference in immunologic responses (p=0.76). When evaluating
the effect of APV BID dose, 0% on 600-mg (N=4), 21.7% on 750-mg (N=23), 35.3%
on 900-mg (N=17) and 80.0% on 1200-mg (N=5) achieved VL<50/mL by 4-6 M (p=0.03).
This relationship persisted using logistic regression controlling for NNRTI-experience
and use (p=0.01).
Conclusions: The combination of APV and LPV/r in salvage therapy had
no virologic or immunologic advantage over LPV/r alone; however, the dual-PI
group had greater ARV-experience. The VL response to this dual-PI regimen was
directly related to the dose of APV supporting the in vitro observation of a
pharmacokinetic interaction. When using APV with LPV/r, clinicians should consider
using a higher dose of APV.