Study: 'Rare' Infection During PrEP

Out of the Conference on Retroviruses and Opportunistic Infections (CROI) held in Boston last week came news of a 43-year-old gay man who seroconverted despite being compliant with the drug taken for pre-exposure prophylaxis, or PrEP.
But scientists were quick to point out the case was "rare" and an exception to the high efficacy of the drug. They noted that the patient in the case contracted a virus that had resistance to several drugs used to treat HIV, including both drugs in Truvada, the brand name of the drug that is used as PrEP. Studies on the virus the man contracted showed resistance to drugs in nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, and integrase inhibitors classes of drugs.
Drug resistance is linked to people living with HIV failing to continue to take their prescribed medicine properly — cited reasons for this include missing doses or not taking them on time. In Michigan, a study of newly diagnosed people living with HIV found 15.3 percent of cases of the virus contained resistance to at least one drug used to treat HIV. About 11 percent of the 422 cases studied had resistance to the two drug classes found in Truvada.
Angela Minicuci, a spokesperson for the Michigan Department of Health and Human Services, said the state data could not be parsed to determine how many of those viruses studied had resistance to both drugs in Truvada.
"We don't have a way to link up genotypes with the data collected on the case report form either because those algorithms and software are only housed at CDC," Minicuci said in an email Friday. "We can watch if NRTI resistance is increasing in general, and perhaps correlate that to PrEP prescriptions. We will have a new MHS report coming out soon but because it is CDC data, there is a significant lag in the timing and the data would likely be a year behind."
Despite the heavy resistance to three of the seven classes of HIV medications, scientists reported the man was able to start treatment and has suppressed his viral load.
While the case was trumpeted as evidence of a need for caution related to PrEP as a prevention option by some, the scientists stressed that having resistance to both drugs found in Truvada is exceptionally rare, and very unlikely to happen on a regular basis. Scientists said testing and pharmacy records provided evidence to show the man was likely compliant with the drug regimen — taking it daily as prescribed.
Studies have put the efficacy of the drug when taken daily at over 92 percent effective. A model of efficacy from the National Institutes of Health put the efficacy at 99 percent. In addition to PrEP, those living with HIV who take their medications properly and suppress their virus to "undetectable" levels are significantly less like to transmit the virus. That intervention is known as treatment as prevention, or TasP.
At the same conference, the CDC released a study showing that PrEP in combination with TasP and increased testing could significantly reduce new HIV infections in the U.S.
"Reaching the nation's treatment goal of ensuring 80 percent of all of those diagnosed with HIV achieve viral suppression (that is, keeping their virus under control and at a level that dramatically reduces the risk of transmission) alone would prevent an estimated 168,000 infections over the next five years," the federal agency reported on its website. "Increasing the use of PrEP, a daily anti-HIV pill, among people who are uninfected but at high risk could prevent an additional 17,000 infections over the same time span."
"If we expand the use of our current prevention strategies today, we can significantly reduce new HIV infections tomorrow," said Dr. Jonathan Mermin, director of CDC's National Center for HIV/AIDS, Viral Hepatitis, STD, and Tuberculosis Prevention. The statement was made in the same press release. "This study confirms that we have the right tools to dramatically reduce new HIV infections, but we have a long way to go in order to make those reductions a reality."
There are currently an estimated 48,000 new HIV infections in the U.S. annually — with a significant number of those infections in men of color who have sex with men. Another study released by the CDC found that one in two black men who have sex with men could be infected with the virus in their lifetime.