A Randomized Trial to Evaluate Continuation versus Discontinuation of Lamivudine in Individuals Failing A Lamivudine-Containing Regimen: The Colate Trial

Abstract

Background

Lamivudine (3TC) therapy can cause the emergence of M184I/V. Previous studies suggest a higher fidelity of the mutant reverse transcriptase and lower replication capacity of the mutant virus. No data exist from clinical comparative studies evaluating the benefit of M184I/V in patients receiving combination antiretroviral therapy (cART).

Methods

HIV-1-infected adults failing a 3TC-containing regimen were randomized to continue (On-3TC) or discontinue 3TC (Off-3TC) whilst receiving cART. The primary efficacy measure was the log₁₀ average-area-under-the-curve-minus-baseline reduction in HIV RNA over 48 weeks. Cryopreserved plasma samples from patients with baseline and ≥1 follow-up sample with HIV RNA >500 copies/ml were sequenced for a nucleotide distances substudy. Evolutionary distances were compared between treatment arms and between viruses with and without M184I/V

Results

The overall 48-week log₁₀ HIV RNA change was -1.4 (95% CI: -1.6, -1.1) for On-3TC (n=65) and -1.5 (95% CI: -1.7, -1.2) for Off-3TC (n=66; P=0.51). No difference was seen in the magnitude of the CD4⁺ T-cell count increases (median increase: 87 vs 76 cells/ml for 3TC vs Off-3TC, respectively). Thirty-seven patients had baseline and follow-up sequencing. Overall, there were 1.2 (95% CI: -2.2, 4.6) more nucleotide substitutions from baseline for Off-3TC patients (P=0.50), and 10.7 (95% CI: 7.5, 14.0) fewer nucleotide changes in viruses containing M184I/V (P<0.0001).

Conclusion

This study found no added virological or immunological benefit of continuing 3TC in patients on cART harbouring M184I/V Evolutionary distances from baseline were larger in viruses that did not contain M184I/V. More discernable benefits may be seen in patients with fewer drug options as potent cART may eclipse a benefit of M184I/V in COLATE.