Marc Walker had many worries in April when he first stepped into the manila office building above a FedEx on Market Street in University City.
He’d recently stopped taking pre-exposure prophylaxis, called PrEP, a daily pill regimen shown to be effective at preventing HIV. He got nervous about the chance of a side effect that might damage his liver.
Walker, who does not have HIV, wondered whether researchers at the University of Pennsylvania would give him a high dose, low dose or a placebo of an antibody that has controlled the virus in another man. But he won’t find out for two years.
Having read a packet in preparation, he’d learned that researchers didn’t know if the antibody — which they would deliver via infusion over the next two hours — would prevent HIV. If it does prove effective, the goal is to reverse-engineer a vaccine that would trigger the body to produce on its own the same kind of protective antibody.
“I had a lot of questions, but they answered all of them,” said Walker, who is gay, a couple weeks after his first infusion. “You’re going to have a guinea pig for everything. Every drug that’s out there, there had to be human guinea pigs that had to try it … If I could prevent HIV without having to think of taking something daily, then yeah, I’d take a vaccine.”
Study design
Walker is one of 27 participants Penn has enrolled so far in a new study called the AMP study for antibody-mediated prevention. Four participants are transgender women. Recruiters are also looking for trans men. It’s the first time they will be included in an HIV vaccine study.
Deb Dunbar, clinic coordinator for Penn’s portion of the study, served on the team through the National Institutes of Health that designed the study. She called it a “benign oversight” that trans men had not previously been asked to participate. Because estrogen has some impact on HIV susceptibility, it took time to include trans women who were taking hormones in HIV studies. Once trans women were included, Dunbar said, it naturally followed to include trans men.
There are 125 people enrolled so far in North America for the AMP study, which will eventually become a 4,000-participant international study funded by the NIH. It opened in April after being developed for just over a year by a 30-person team of scientists, physicians, regulatory and laboratory experts working with the National Institute of Allergy and Infectious Diseases, which is part of the NIH.
The institute’s HIV Vaccine Trials Network and HIV Prevention Trials Network collaborated on the AMP study.
The study uses antibodies that have all been cloned from one man with HIV whose body naturally produced an antibody that controls the virus. Participants alternate every four weeks between getting an infusion, which comes with $100 compensation, and getting an HIV test, which comes with $50. The process lasts for 20 months.
“We try to enroll the highest-risk folks,” Dunbar said. “Sometimes that means people who do a little sex work. If they can make more money doing sex work than coming here, we want to be competitive with that.”
Multiple strategies welcome
Tyler Doppelheuer, another study participant, brought his laptop with him to take care of some business during his first infusion this spring. The health-care consultant said he’s long been interested in HIV prevention and participated in several Penn studies in that vein.
“A lot of the materials and results that I receive, I send over to my primary [doctor],” said Doppelheuer. He added participating in the vaccine study has made him talk more about PrEP, which he takes, with his friends. It has opened the doors for wider conversations about sexual health and HIV prevention, he said.
Doppelheuer said he has a very regimented morning routine that makes it easy for him to remember to take PrEP daily, but he liked the idea of participating in research that could one day make vaccines a viable preventative option for those who would prefer a long-acting strategy.
Dr. Ian Frank, principal investigator for Penn’s portion of the study, said vaccines and PrEP could be combined with other prevention strategies in the way diet, exercise and cholesterol medication can be variously combined to prevent heart attacks.
“This is not this or that,” Frank said. “It’s an and.”
He added researchers would like to reverse-engineer a vaccine because it would be cheaper and could last for years, instead of months, like an antibody infusion, should it prove effective.
“Maybe it isn’t too expensive to use in the United States,” Frank said. “But in South Africa, people are not going to be coming in for infusions every two months. In South Africa, 20 percent of the population is HIV-infected. People are going to have contact with people who have HIV. You can’t have the whole sexually active population coming in for infusions.
“You want an inexpensive approach to prevention,” he added. “One that doesn’t cause a lot of side effects and one that doesn’t require somebody to strictly adhere to some kind of a prevention regimen.”
For more information, visit www.phillyvax.org or www.ampstudy.org.