Canadian patient acquires HIV while being on PrEP

The New England Journal of Medicine has published data from David C. Knox, MD, of the Maple Leaf Medical Clinic in Toronto and described what is considered to be the first case of a patient contracting HIV despite long-term adherence to pre-exposure prophylaxis, or PrEP. It is the first case to demonstrate failure with Truvada (emtricitabine/tenofovir disoproxil fumarate), the drug developed by Gilead and widely used for pre-exposure prophylaxis with a proven prevention efficacy of around 95% in patients who adhere to the once-a day regimen treatment.

Pharmacy records show that the 43-year-old Toronto resident was adhering to the treatment as prescribed but was infected with HIV after having condomless sex with another man. Based on a genetic analysis of the virus, it was revealed that the patient acquired the virus with a mutation, M184V, which compromises FTC activity; plus several thymidine analogue mutations, which slightly decreases TDF susceptibility.

"There's tens of thousands of people who are believed to be on HIV PrEP, and there have been only two documented cases of people who were infected with drug-resistant strains of HIV.I wouldn't use this case as a reason to stop taking PrEP or to dissuade anybody from initiating PrEP if they are at high risk for HIV." Knox said.