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Resistance by PrEP linked to acute seronegative infections at initiation
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New data suggest that although resistance selected by pre-exposure prophylaxis, or PrEP, is rare among those who acquire HIV, it can occur in patients with unknown acute HIV infection at PrEP initiation, according to data published in the Journal of Infectious Diseases.
“Multiple clinical trials have shown that the use of PrEP is a safe and effective HIV prevention method,” Dara Lehman, PhD, of the Fred Hutchinson Cancer Research Center and the University of Washington in Seattle, told Infectious Disease News. “However, before PrEP is rolled out on a large scale, it is important to understand the risk of drug resistance in those who become infected while taking PrEP. These data confirm that the risk of resistance from PrEP is low, and that the number of HIV infections averted by PrEP use outweighs the risk of drug resistance.”
Lehman and colleagues used data from the Partners PrEP study to evaluate resistance associated with PrEP. The Partners PrEP study included HIV-negative partners from 4,747 serodiscordant couples who were randomly assigned emtricitabine/tenofovir disoproxil fumarate (FTC/TDF; Truvada, Gilead), TDF alone (Viread, Gilead Sciences) or placebo. For this analysis, the researchers evaluated the plasma from 121 patients who seroconverted during the study. They performed 454 sequencing on plasma samples taken when the seroconversion was detected and/or 1 month after seroconversion to determine the presence of resistance mutations.
They identified five patients with PrEP-related resistance mutations, including K65R, K70E and/or M184IV, at frequencies of more than 1%. The patients had evidence of PrEP use during infection: four in the FTC/TDF arm and one in the TDF arm. All cases in the FTC/TDF arm had M184IV mutation or M184V mutation alone.
Resistance was mainly associated with individuals who had an unknown acute infection when they began PrEP. Among the five patients with evidence of PrEP use and a resistance frequency of more than 1%, three cases of resistance occurred in individuals with unrecognized acute infection: two patients in the FTC/TDF arm and one in the TDF arm. Two seroconverters assigned to active PrEP who were infected after enrolling in the trial had a resistance frequency of more than 1%, and both were in the FTC/TDF arm.
“This study was done in the context of a carefully monitored clinical trial setting in which participants were tested for HIV on a monthly basis,” Lehman said. “We are interested in determining the rate of PrEP-related resistance that occurs in clinical settings in which HIV monitoring and clinic visits occur only every 3 months, where there may be a longer time in which PrEP is taken between HIV infection and the detection of HIV and cessation of PrEP.” – by Emily Shafer
Dara Lehman, PhD, can be reached at: dlehman@fhcrc.org.
Disclosure: Lehman reports no relevant disclosures.
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