The effect of lopinavir/r monotherapy on viral load and on the selection of resistance-associated mutations in seminal plasma
E. Nunes1,2, M. Santini-Oliveira2, S. Tuboi1, R. Diaz3, T. Vergara3, M. Norton4, M. Schechter1
1Universidade Federal do Rio de Janeiro, Projeto Praça Onze, Rio de Janeiro, Brazil, 2Fiocruz, Instituto de Pesquisa Clínica Evandro Chagas, Rio de Janeiro, Brazil, 3Unifesp, Laboratorio de Retrovirologia, São Paulo, Brazil, 4Abbott Laboratories, Virology, Linden, United States
Background: Although lopinavir/r monotherapy is considered by some as an attractive simplification strategy, others have expressed concerns relative to the potential lack of efficacy in sites with poor drug penetration, such as the genital tract.
Methods: KalMo was a randomized, open label 96-week study to assess the efficacy and safety of using LPV/r monotherapy in patients with no prior virologic failure and on a stable, successful HAART regimen for at least 6 months. Patients were randomized (1:1) to either switch from HAART to LPV/r monotherapy or to maintain their previous regimen. Semen samples were collected at the end of follow-up. Seminal viral load was measured by Real- time PCR. Genotypic resistance analysis was performed on every sample that had a detectable viral load.
Results: Semen samples were collected from 15 male patients randomized to monotherapy, all of whom had undetectable plasma viral load at the end of the follow-up period. Only one patient had a detectable seminal viral load (260cp/mL). This was a patient who experienced virologic blips during his follow-up, and had a plasma viral load of 850 copies/mL at a post-study visit performed two weeks after semen was collected. Genotypic resistance analysis on the semen sample showed a pattern similar from that obtained in plasma at week 48 and at the post- study visit, including 2 primary mutations on positions 46 and 84 and minor substitutions on positions 15 and 63.
Conclusions: In our study Lopinavir/r monotherapy was effective in suppressing viral load in semen samples. Virus present in seminal and blood plasma had similar resistance associated mutations.
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