LONDON — Drug resistance acquired in rare cases of HIV infection during treatment with pre-exposure prophylaxis (PrEP) rapidly disappears once medication is discontinued, investigators report in the journal AIDS. Use of ultra-sensitive tests performed six months after seroconversion and discontinuation of PrEP failed to find any resistant virus, AIDSmap reports.
“Multiple studies have now shown that the risk of developing resistance from PrEP is very low, but is an important concern for those who initiate PrEP during unrecognized acute infection,” researchers wrote. “Our data show that resistance selected in these cases decays rapidly to levels below detection of even highly sensitive assays.”
PrEP with emtricitabine/tenofovir (Truvada) or tenofovir (Viread) alone is highly effective at preventing infection with HIV. However, resistance to these antiretroviral drugs has been detected in individuals who initiated PrEP during unrecognized acute HIV infection, and, very rarely, in patients infected with HIV while taking PrEP, AIDSmap reports.
Such resistance could limit future HIV treatment options. It is therefore important to determine if it persists once treatment is withdrawn. To answer this question, investigators from the Partners PrEP study designed a longitudinal study involving nine patients who had drug-resistant HIV of various mutations detected during HIV seroconversion.
By testing archived blood samples taken of the virus six, 12 and 24 months after they stopped taking PrEP, researchers found that the resistance appeared to be related to the PrEP usage as their levels of resistant virus fell to undetectable levels in all nine patients and stayed at those levels six, 12 and 24 months after they stopped taking PrEP, AIDSmap reports.