Resistance to drugs acquired in rare cases of HIV infection during treatment with pre-exposure prophylaxis (PrEP) quickly disappears after discontinuation of the medication, the researchers report in a report on AIDS. Using ultrasound tests performed six months after seroconversion and abandonment of prEP in failure, did not find any remnant of resistant copies.
Several studies have shown that the risk of developing PrEP resistance is very low, but it is a major concern for those starting PrEP during acute unrecognized infection, the authors write. "Our data show that the selected resistance in these cases decays rapidly to levels below the highly sensitive detection of the same assays."
PrEP with tenofovir and emtricitabine (Truvada) or tenofovir (Viread) isolate is highly effective in preventing HIV infection. However, resistance to these antiretroviral drugs has been detected in individuals who initiated PrEP not recognized during acute HIV infection, and very rarely, in HIV-infected patients receiving PrEP.
Such resistance may limit future treatment options for HIV. Therefore, it is important to determine if it is important or necessary to persist after discontinuation of treatment. To answer this question, researchers from the Partnes study on PrEP designed a longitudinal study involving nine patients who had resistance to anti-HIV drugs (with K65R, K70E and / or MUMUXV mutations) detected during seroconversion. The archived blood samples were tested to see if resistance was transmitted or acquired because of PrEP. Ultra-sensitive assays were used to monitor virus-resistant strains six, twelve and 18 months after PrEP cessation.
Blood samples that were archived with RNA from HIV-positive, antibody-negative individuals were available prior to seroconversion to four of nine patients. None of these patients had resistance mutations prior to seroconversion, suggesting that resistance was acquired due to PrEP therapy rather than being transmitted.
PrEP was stopped immediately after detection of seroconversion. Ultrasensitive assays were used to see if the resistance persisted after PrEP was withdrawn.
Resistant virus levels had declined - or fallen - to below the detection limit in all patients six months after treatment had been discontinued and remained undetectable twelve and 24 months after follow-up.
"Resistance related to PrEP falls rapidly after PrEP cessation," the researchers commented. "For six months after seroconversion (after PrEP was discontinued), the K65R, K70E and / or M184IV resistance mutations that were present in the seroconversion were no longer detectable, even with highly sensitive resistance testing."
Only one patient started treatment with antiretrovirals (ART) within 40 months after seroconversion. This patient started treatment at month 33, taking a combination of nevirapine / emtricitabine and tenofovir. Viral load was approximately 19.000 copies / ml. Three months after starting ART, this patient had an undetectable viral load.
The researchers were called for further studies to examine whether PrEP associated with resistance affects subsequent response to treatment.
Translated by Claudio Souza's original During acquired drug resistance HIV PrEP rapidly disappears after medication is discontinued.
Reviewed by Mara macedo
Written po Michael Carter
Posted in: 14 December 2015