From the "Swiss statement" to the overwhelming success of studies such as PARTNER and HPTN 052, HIV treatment as prevention has become a well-known and powerful tool in the global HIV response. Could there be a future for this model in the prevention of hepatitis C -- a virus with a number of characteristics in common with HIV, as well as notable differences in detection and management?
Mark Sulkowski, M.D., medical director of the Johns Hopkins Infectious Disease Center for Viral Hepatitis, discussed the treatment-as-prevention concept during a symposium at IDWeek 2015 in San Diego, Calif. I caught up with Dr. Sulkowski afterward to learn more about this potentially exciting development in hepatitis C management and prevention.
Talk to me about the concept of hepatitis C (HCV) treatment as prevention. Where do you see overlaps with the treatment-as-prevention model in HIV, and what are the potential limitations of this model for HCV?
The concept of treatment as prevention is certainly not new. It really comes from the HIV world, where studies have proven that individuals who take highly effective antiretroviral therapy and suppress their HIV RNA to undetectable levels have a lower risk of transmitting to others. That model has been proven.
In hepatitis C, the outcome of therapy is cure. So the idea is, if you cure someone, they won't transmit to other people. In theory, it makes a lot of sense. But I think we have to be cautious. Remember that it took a long time for HIV treatment as prevention to be accepted and to be the standard practice or concept.
In hepatitis C, we don't really have any evidence that treatment as prevention works. But we have two groups of individuals with hepatitis C, in general, who previously engaged in behaviors that placed them at risk to transmit to others.
We also have people who really never engaged in high-risk behaviors. They received blood transfusions or got their hepatitis C through contaminated blood in some other form, but they weren't actually engaged in high-risk injection drug use or high-risk sex. When you treat those folks, they benefit because you cure their hepatitis C and their liver disease won't progress. But you haven't done anything about prevention, because they were not at risk to spread it to begin with.
This leads us to the two groups that are at risk of transmitting HCV. The first is, in particular, HIV-positive men who have sex with men, for whom transmission of hepatitis C is occurring where one individual has both HCV and HIV, and the other just has HIV. We're seeing transmissions; that's being reported in many cities around the world. It's a pretty well-accepted phenomenon now.
The other group is persons who actively inject drugs. If you're actively injecting and you have hepatitis C, and others were to use that needle, or potentially even water or some other injection material that was contaminated, they could be infected. The point is, if you can cure that person, you could render them no longer infectious and then break the chain. In theory, that is what would happen.
But we don't really have anything other than models that demonstrate how that would play out. So a lot of people are talking about this, and there are proposals for studies. For example, Greg Dore's group in Australia is getting ready to carry out such a project, and there's talk of such things in the United States, as well. But, to date, it's really just a concept.
There's one major potential flaw -- that it is very easy to become reinfected with hepatitis C after being cured. So for a person who's at high risk to transmit to others, who by definition is at high risk to become reinfected -- how do you ensure that person remains HCV negative?
The other concern is, while we could treat again and again (there's no limit to how often we could cure someone with hepatitis C) there is a major discussion about the cost of treatment. Unlike HIV where it's a chronic therapy, these are really the short courses.
A lot has to be worked out. We probably need to develop different strategies that focus on communities or networks, if you will, of high-risk individuals -- not particularly on individuals.
Taking the HIV treatment-as-prevention model as an example, knowing that there are clearly significant differences in the treatment and management of HIV versus HCV, how long do you think it will be before we see the results of an HCV treatment-as-prevention study?
It really depends on what population you're focused on. Just this week, the government of Iceland announced they plan to eradicate hepatitis C in that country. Now, there, it's quite feasible. It's a small country. It's got water around it. It's quite possible they could actually achieve eradication of hepatitis C in Iceland.
On the other hand, if you look at more dynamic populations, it's really difficult to say if it's even possible. In fact, many people think that you really can't treat your way out of the problem of hepatitis C -- that we really do need a vaccine. So if we had an effective vaccine, what you would do is cure an individual, and then you would vaccinate them. And you would render them immune to reinfection, thereby truly breaking the transmission chain.
As of right now, we don't have an effective vaccine for hepatitis C.
This transcript has been lightly edited for clarity.