Evolution of Resistance Mutations during Low-Level Viral Replication in HIV-1–Infected Patients Treated with Zidovudine/Lamivudine/Abacavir as a First-Line Regimen
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Medientyp:
E-Artikel
Titel:
Evolution of Resistance Mutations during Low-Level Viral Replication in HIV-1–Infected Patients Treated with Zidovudine/Lamivudine/Abacavir as a First-Line Regimen
Beschreibung:
<jats:sec><jats:title>Objective</jats:title><jats:p>Long-term evaluation of viral evolution in patients who continued first-line therapy with zidovudine/lamivudine/abacavir (Trizivir [TZV]) in the presence of low-level viral replication and assessment of the impact of mutational patterns selected under TZV on viral load (VL), CD4<jats:sup>+</jats:sup>T-cell count (CD4) and subsequent therapeutic options.</jats:p></jats:sec><jats:sec><jats:title>Design</jats:title><jats:p>Analysis of viral evolution based on genotypic resistance tests (GRT) from samples collected during non-suppressive first-line therapy with TZV.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Patients from the Frankfurt HIV cohort with at least 3 months uninterrupted first-line therapy with TZV in whom VL and CD4 measurements were performed at baseline and at follow up were identified. Criteria for virological failure (VF) were two consecutive VL >400 copies/ml. GRTs were required at baseline, VF and last visit (LV).</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Initially, 23/119 patients were classified as VF; 4/23 were lost to follow up. Median time to VF was 48 weeks. Because of the observed virological and immunological benefit, patients continued TZV for a median of 87 weeks despite detectable viraemia. Median CD4 increase and VL reduction at LV were 120 cells/mm<jats:sup>3</jats:sup>and 317,100 copies/ml, respectively, compared to baseline. After 54 weeks of treatment with detectable VL, three mutational patterns were observed: Group A ( n=4) characterized by M184V without further regimen-associated mutations, group B ( n=9) by M184V accompanied by one to three thymidine analogue mutations (TAMs), and group C ( n=6) by M184V and four to six TAMs. No virological or CD4 parameters correlated with these patterns. Group A remained unchanged, thus preserving activity of most nucleoside analogues (NA). However, in the majority of patients (groups B and C) accumulation of mutations at different rates was observed, leading to a sequential loss of NA options.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Continuous treatment with TZV in the presence of viral replication is associated with a stepwise accumulation of resistance mutations. M184V was present in all cases, not followed by further selection of TAMs in a small, unpredictable subgroup of patients. However, in the majority of patients selection of M184V was associated with accumulation of TAMs at different rates leading to a substantial loss of active NAs, despite continuous virological and immunological benefit when compared with baseline.</jats:p></jats:sec>