There’s no HIV vaccine yet, but research on injectable PrEP and vaginal rings may yield new prevention and treatment solutions.
Development of an HIV vaccine remains slow and, so far at least, vaccine candidates have not been very promising in terms of conferring total protection against the virus.
But those gathering this week for the first-ever HIV Research for Prevention (HIV R4P) conference in South Africa were buoyed by news of research on injectable pre-exposure prophylaxis drugs and microbicides.
Speaking at a press conference on Monday, Dr. Ian McGowan of the University of Pittsburgh offered preliminary news about clinical trials for TMC278-LA, a long-lasting, injectable form of rilpivirine. Rilpivirine is a powerful new non-nucleoside reverse transcriptase inhibitor, or NNRTI.
The drug is being studied both for use in HIV treatment and prevention.
In trials conducted on 36 men and women with HIV, the drug suppressed their viral loads to undetectable levels within a month, McGowan reported. “The injection was very well tolerated and safe and acceptable,” McGowan said, calling its ability to suppress viral load “profound.”
On the prevention side, large amounts of the drug remained in rectal tissue four months after injection, “showing remarkable persistence of the antiretroviral effect,” McGowan said. However, very little of the drug persisted in vaginal tissue after four months.
Larger phase II trials, including 225 subjects, are set to begin in Pittsburgh in December.
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In a separate development, Meredith Clark of CONRAD, a nonprofit organization dedicated to contraception and HIV and AIDS research, presented work showing that tenofovir reservoir vaginal rings not only protect against HIV, but also herpes.
Dr. Jeanne Marrazzo of the University of Washington in Seattle said that Clark’s findings were intriguing because herpes and HIV “go hand in hand.”
Because the disease presents open sores, people with herpes are more likely to transmit the virus, and people with herpes also are more likely to contract it.
Research is also underway that could offer doctors a way to determine exactly where a person’s HIV infection came from, a sort of “virus fingerprint” that could offer clues toward better treatment and prevention.
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Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told attendees via video that while he does believe an HIV vaccine will eventually come to fruition, it may only be modestly effective.
Fauci stressed the importance of using tools already at our disposal, such as Truvada as pre-exposure prophylaxis, or PrEP.
With any non-vaccine prevention method, adherence is the biggest challenge, according to Fauci. He stressed that the best prevention is testing and focusing prevention efforts on so-called “hot spots” where the virus is prevalent.
Fauci cited San Francisco’s Castro district as an example, and urged health workers to “push” PrEP. Truvada as PrEP is “close to 100 percent effective when taken four or more times per week,” he said.
When a person tests negative for HIV, a risk assessment should be performed, with prevention methods tailored to that particular person, Fauci urged.
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In a separate presentation, Dr. Chris Beyrer, director of the Johns Hopkins Center for Public Health and Human Rights in Baltimore, discussed why PrEP is so underutilized in the United States.
Beyrer cited stigma against homosexuality and lack of access to basic medical care as roadblocks to implementing this important prevention tool. Certain populations, Beyrer said, are at especially high risk of transmission and do not receive the preventative care they need.
Beyrer said, “Sex workers are really facing systematic discrimination in healthcare facilities. Transgender women worldwide are 48.9 percent more likely to contract HIV. Now that’s a health disparity.”