Transcripts: amfAR Scientists Discuss Their Cutting-Edge HIV Cure Research

Interview with Dr. Nicolas Chomont:

Dr. Chomont: I'm trying to understand how HIV hides during antiretroviral therapy and what we are trying to do with the support of amfAR is to find the cells in which HIV is able to persist during very long-term antiretroviral therapy.

amfAR: Does that happen in all patients?

Chomont: That happens in pretty much all patients except the ones that start receiving treatment very early on. There is some data right now showing that if you treat very early on you can prevent the establishment of this latent reservoir. But even if you do so, by using a very sensitive assay, you can always find cells in which HIV has established those latent reservoirs.

amfAR: Are you working with any patients who have very very early therapy?

Chomont: We do. We actually have access to two different cohorts of patients who start receiving ART early. The first one is the one that's been developed by the French at ANRS, which is called the VISCONTI patients, and Asier Saez-Cirion from Institut Pasteur is part of this ARCHE collaboration. He's trying to understand why these people do not rebound when ART is interrupted. The other cohort of very acute infection that we are working with is the one developed by the Military HIV Research Program and the Thai Red Cross—in collaboration with Jintanat Ananworanich and others— that is people who started receiving ART very very early on, as early as Fiebig one, which is basically the first few weeks after HIV infection. The work we have been doing so far shows that in those patients who started receiving ART very early on, the frequency of cells in which HIV establishes a reservoir is extremely low and usually undetectable.

amfAR: What is amfAR's role in supporting this research?

Chomont: amfAR basically put all of us together. We are large group of people coming from different continents—from the U.S., Thailand, from Australia, from France. amfAR gave us the opportunity to all work together. The idea of this was not only to exchange ideas, which of course is great, but also to exchange patient samples because we share different expertise. By putting everything in common, in the context of this ARCHE amfAR collaboration, I think we're going to get the best we can do with the samples.

amfAR: What are the biggest challenges you need to overcome?

Chomont: One of the biggest challenges is of course to get rid of the viral reservoir. But I would say that even before that, what we have to develop are assays that will give us a very clear and precise idea of the size of the latent reservoir. There is still a lot of controversy in the field about what should be measured; what is correlated to viral rebound or viral control after antiretroviral interruption. I think we still don't know, so we still have a lot of work to do in this area.

amfAR: How optimistic are you that we will find a broadly applicable cure for HIV in the next five or 10 years?

Chomont: You know, the news of the Mississippi baby and the Boston patients has been quite depressing to the field, but I think we should not get depressed at all. I'm actually very confident. I think all the progress that has been made in the field of HIV vaccination, for instance, is very promising. I think pretty much everyone now agrees that we will not find a cure by only trying to get rid of the reservoir, but we also have to induce some kind of control that will be mediated by the immune system. I think that in this area we have made considerable progress in the past few years, so I'm very confident.

Interview with Dr. Steven Deeks:

Dr. Deeks: We’re interested in untangling the complex relationship that exists between the immune system of a person on antiretroviral drugs and the amount of virus that exists in that person.

amfAR: Why are you interested in doing that?

Deeks: The central theme of our work is that if you can figure out what characteristics of the host immune system define how much virus is around, then we can identify immune-based therapeutics so that we can get rid of the reservoir.

amfAR: Ultimately, would you say your goal is to try to cure HIV?

Deeks: Our goal is to harness the immune system to reduce the amount of virus or control the amount of virus. It's a combination approach to curing HIV.

amfAR: What are the biggest challenges or hurdles that you need to overcome?

Deeks: The most fundamental thing that we're struggling with is that the immune system in humans—or immune systems in general—is incredibly complex. At the end of the day, you can do all these descriptive studies, but you're never really going to understand what's happening unless you take an intervention, a drug, and do something to the immune system and see what happens. Those types of studies are hard to get off the ground for a variety of reasons. That's been the major thing that's blocked us from understanding the things that we’re most interested in.

amfAR: How has amfAR been supporting your work?

Deeks: amfAR’s been supporting our work for several years now. Probably in terms of the issue of how the immune system controls the virus, the best examples of that happening are the so-called elite controllers. Several years ago, with a very important pilot grant from amfAR, we developed a cohort which I think has now grown into one of the largest, if not the largest, single-center cohort of elite controllers. That group of HIV-infected people who control virus on their own is being used to support a lot of research over in San Francisco and around the world. So that was the first thing.

And then after that, we got involved in the ARCHE collaboration, which led to a whole number of really important studies including one with the Siliciano laboratory, which led to a really high-profile, high impact paper that looked at the various different ways of measuring how much HIV persists in individuals. At around that time, the Berlin patient, who remains the last man standing in terms of the cure world, showed up in San Francisco. With amfAR funding, we were able to do a series of investigations to see to what degree Mr. Timothy Brown was cured, and this involved accessing the ARCHE collaboration that amfAR had initially put together.

I think currently we're doing a fair amount of work with amfAR funding on two questions. We're supporting Nicolas Chomont and his team to figure out what happens in individuals after they've been on therapy for 15 or so years. This is the first time anyone has tackled that question. And we are supporting some really innovative work to try to figure out whether or not the amount of HIV that persists in women differs in any way from men. No one has ever tackled that question.

Interview with Dr. Victor Garcia-Martinez:

Dr. Garcia-Martinez: Our research is focused on HIV cure. We’re trying to find ways in which we might be able to eradicate the virus from the body. For that, we're taking advantage of a model that we developed a few years back called the bone marrow-liver-thymus or BLT mice. Those are very special animals in the sense that they recapitulate very key aspects of HIV infection, including latency. It provides us with an in vivo model in which we can actually test a variety of novel approaches before they can be implemented in the clinic. We can take a lot of risks that you can't take with a patient.

amfAR: How important is it to be able to do work in animals before you go to humans?

Garcia-Martinez: It's of fundamental importance to do experiments in animals before you do humans. The proof of principle that you need in order to translate into clinical application is one of the fundamental aspects of the scientific enterprise. We can perform experiments much faster. We can ask deeper questions. We can perform analysis that would be impossible to do in a human being. In that sense, I think animal experimentation in this particular context is extremely well ethically justified.

amfAR: Can you give us an example of something you can do in your mice that can't be done in humans?

Garcia-Martinez: One of the most important questions currently is where are the HIV-infected cells that represent the reservoir responsible for the continuous presence of the virus despite extended years on therapy. We don't know where they are. We can't go and look in the liver of an infected individual. We can't go and look in the thymus or spleen or in the lymph nodes. But in the mice we can. We can go and dissect exactly where they are, how many are present, where they last longer, and then, if we have a way to eradicate them, we can actually count how many cells get killed in each specific tissue.

For example, people are very concerned about the brain. The brain is a reservoir of HIV. It would be impossible to go and do any type of experiment that asks how many latently infected cells are in the brain of a human being. That is the type of experiment that is extremely sophisticated, is extremely expensive, is virtually impossible to do in any other system except perhaps non-human primates and humanized mice. I think it challenges us to come up with experiments that were impossible before—that you wouldn't even think of because it would be perceived to be just not feasible. But now we can do them and I think the information is forthcoming.

amfAR: What are the biggest challenges you face with your work?

Garcia-Martinez: The main challenge we face with our work is to keep thinking out-of-the-box; to keep the preconceived notions that we have from influencing what we do next; to try to really let go of what we perceive to be the truth to actually find out what exactly the truth is. When we face that, we not only face it ourselves in our own daily life, but we actually face it with the people that are judging what we do. Particularly the people who fund the work that we do in the sense that they get an aggressive proposal that is looking at parts of the anatomy or parts of the science that have not been probed before, and it’s sometimes difficult for people to make that leap of faith that we will be able to find something. Or more importantly, that it's worth their money to let us take the risk. I think we need innovation. I think we need an opportunity to go where nobody's been before. I think a lot of people would have a very difficult time letting us do that. I speak for many, not just ourselves.

amfAR: You raised funders. What role has amfAR played in your career, in your research?

Garcia-Martinez: amfAR is the reason I'm talking to you today. When I was a postdoctoral fellow at the Fred Hutchinson Cancer Research Institute, I started to do my independent work. If it had not been for a seed grant from amfAR, we would not be here today. This is going back almost 25 years ago. Since then, amfAR has played an integral role in everything we do. Now, it’s not me receiving the funds, but the people who train under my tutelage that are actually benefiting from having the opportunity to do the work because amfAR is taking a chance on them.

Interview with Dr. Sarah Palmer:

Dr. Palmer: The current focus of our research is to determine where the virus is essentially hiding in the patient’s body when they're on suppressive therapy. So what cells are actually harboring the virus when the patients are taking therapy? Even though the therapy does reduce the virus to very low levels in the plasma, we know that it persists in certain cells. We're really trying to determine which cells harbor the most virus and which cells are most important to be targeted so that we can move the virus from those cells.

amfAR: What are the biggest challenges that you're facing with your research?

Palmer: The largest challenges would be that at times we can't get enough cells from the patients. Even though the patients are very very generous, there is a limit to the number of cells that you can get from patients, so we do have to look at a pretty large patient cohort, so we can make some determination as to where the virus is in their cells during suppressive therapy. But I have to say that, in collaboration with the University of California, San Francisco—they've been very very generous with their patients— and the patients have been very generous with their cells and samples, so we have been able to do some very in-depth studies.

amfAR: And why are you so interested in knowing exactly which cells the virus is in?

Palmer: I think it's really important for us to be able to target those cells with certain... whether it's an agent that can actually stimulate the cells to produce the virus and then purge the virus from these cells. I think it's also important that if we can't really target those cells, those will be the cells that we should actually measure the virus in to see how well we are reducing the reservoir in patients. So I think really identifying the cells where this virus is actually latently held, or the reservoir, the cellular reservoir that's holding the virus during suppressive therapy, is really really key in developing eradication strategies. And also following how well eradication strategies are working.

amfAR: What role has amfAR played in your research?

Palmer: amfAR has been absolutely instrumental in our research. In fact, I began this research in Sweden and the funding for HIV research is very very low in Sweden. At one point I really thought we would just have to stop our program. Even though we had the collaboration built with University of California, San Francisco, we did not have the funding in Sweden. And then amfAR gave us a very large ARCHE grant and that saved our program. From that funding, I've actually graduated two Ph.D. students. I have a third student who will be finishing up in Sweden, and we've been able to actually transfer this work now to Australia. I have two soon-to-be Ph.D. students who will be continuing on with this work. Without the funding from amfAR, this work would not have been done.

amfAR: That's great. Is it fair to say that ultimately you're interested in finding a cure for HIV?

Palmer: Yes, that is my dream. And I hope within my lifetime—and it doesn't have to be me, but I just hope that within my lifetime, we do have a cure for HIV.

amfAR: So how optimistic would you be that we'll find a broadly applicable cure in the next five or 10 years?

Palmer: I think within the next 10 years, I think we will find a cure. I think I'm quite certain of that. I think it's also… it's so helpful for the funding from amfAR, from other countries, the Australian government has also been very generous to our group, so with this funding, this will push the agenda forward, I'm sure of that.

Interview with Dr. Deborah Persaud:

Dr. Persaud: Our major goal is to try to figure out how to make HIV infected children… how to put them in a state of remission such that they won’t require a lifetime of antiretroviral treatment. So how are we doing that? First by studying viral reservoirs in these children—where the virus continues to persist under effective antiretroviral treatment, and then to find out ways to clear those reservoirs in kids with established HIV infection, and in those who do not yet have established infection to try and see if we can block reservoirs or reduce these reservoirs from forming by very early treatment approaches.

amfAR: What are the biggest challenges you face with your work?

Dr. Persaud: The biggest challenge is the population we work with. It’s a pediatric population. As you know, these studies are very intensive with respect of the amount of blood that’s required to conduct these studies, with using the sophisticated tests that are available. Issues around the fact that the virus can hide in tissues, meaning that we may have to extend our studies to include looking at tissues in these children. I think really the difficulty is the population we’re dealing with—the young age and small size and limitation of the amount of blood or materials we can get to really study reservoirs and cure.

amfAR: And I think comparing to adults, it’s hard to take a large volume of blood, for example, from an infant. And it’s hard to do tissue biopsies too, right?

Dr. Persaud: It is. It’s hard to do those things, but I should point out that we’ve had success in studying these reservoirs to date in children. We have over 15 years of experience in using small blood volumes to quantify viral reservoirs in children, but we’ve not been able to extend it to the level of tissue reservoirs. With the recent case in the Mississippi child, and now breakthrough viremia—all be it after a long period of time, 27 months—this really puts us in a position to begin discussions in terms of tissue reservoirs and other reservoirs in these children.

amfAR: You did raise the issue of the Mississippi child. Maybe you could just tell us briefly what has recently happened.

Dr. Persaud: As you know, the Mississippi child was our first case of viral remission. We weren't sure the child was cured but certainly the child had gone two years off of antiretroviral treatment without having rebound, but in the last two weeks has rebounded. The virus has reemerged in the bloodstream of that child.

amfAR: Can you confirm for us, because two years is a very long time to be off therapy with no rebound, that's the longest ever recorded in anybody, isn't it?

Persaud: That's correct. I don't think there's even an HIV-infected adult who's been off treatment, where there's no detectable replication competent virus or HIV-specific immune response present, and have been able to go off treatment for two years or more. In fact, it's 27 months in this child, and we think every month counts in this case. So it is a first. In the field, it's unprecedented in HIV infection in general and certainly for pediatric HIV infection.

amfAR: 27 months is a long time in the life of this child. Do you think there was something unusual about the immune system of this child, or maybe something unusual about the virus?

Persaud: Using the standard assays that we have available in terms of measuring immune responses in children, we've used a standard assay for antibody responses, cell mediated immunity and obviously this child had no detectable HIV-specific immunity. But there may be other immune cells that may have played a role in controlling the virus in this child that we have not yet identified. Certainly we’re going to continue to follow this child to try to understand better why this case of remission. But my own assessment is that since this child had no evidence of active virus producing cells off nearly two years of treatment. The negative HIV-specific immune response really supports the idea of viral persistence in a quiescent cell rather than the immune control of a cell that's continuing to produce virus.

amfAR: Can you tell us, how has amfAR been involved in some of the work that you’ve done?

Persaud: You know Rowena, that amfAR did fund our first pediatric study characterizing viral reservoirs in children on long-term ART. We got a pilot grant from amfAR to support that work. And in the context of that funding, or during that funding cycle, is when the Mississippi child and the case emerged. We were just beginning to develop our cure agenda for pediatrics, so it was certainly seed money that was a catalyst for cure research.

Interview with Dr. Asier Saez-Cirion:

Dr. Saez-Cirion: My research is focused on understanding the natural mechanisms of control of infection. We're studying in vivo models of control like natural HIV controllers, monkeys controlling infection, and also post-treatment controllers from the VISCONTI study.

amfAR: You've just mentioned VISCONTI. Can you tell us a little bit about what that is?

Saez-Cirion: The VISCONTI study is studying some people that are in remission from HIV infection, who were treated for many years in the very early stages of infection, and who have been able to control infection after the interruption of treatment for many years.

amfAR: Do you work directly with the patients or do you work with samples of blood, for example?

Dr. Saez-Cirion: Because of ethical reasons we don't have the right to meet with patients when we are conducting the research. We work with clinical partners that refer to us the patients and the samples from the patients.

amfAR: What are the greatest difficulties for you when you're doing your research? What are the big challenges you have to work with? Scientific challenges.

Dr. Saez-Cirion: The scientific challenges are to understand the mechanisms of control in populations. Even if they have a very clear phenotype, the mechanisms are probably very heterogeneous. So trying to pick one mechanism that explains the whole control of infection or the whole phenomenon of remission is tricky, so we need to have a large group of patients to be able to identify the mechanisms that are probably the most relevant ones.

amfAR: So if you found the mechanisms that would explain how the VISCONTI patients, for example, can control their infection even though they're not taking antiretroviral therapy, what would you do with that information?

Dr. Saez-Cirion: The idea is to be able to take that information to be able to create new therapies to apply to other patients. For instance, we know right now that the VISCONTI patients were treated, all of them, from primary infection and that that has a huge impact on the level of the reservoir. We know that this is not sufficient, but it's a starting point. All the VISCONTI patients have lower reservoirs and this is the point that we want to start with in other patients. We need to identify other mechanisms or markers that will allow us to further proceed from treatment interruption trials with more chances of success to achieve remission.

amfAR: Has amfAR played any role in your research?

Dr. Saez-Cirion: amfAR has contributed to allow us to implement new technologies in the laboratory. Actually, it also helped us to recruit a new postdoc to the laboratory to develop this whole new idea of research in my team. Also, it's helping us to better understand how the reservoir is seeded in the primary CD4 T cells; also, taking into account the conditions of the primary infection when compared to the current phase of infection.

amfAR: Are you working with other people that were funded by amfAR?

Dr. Saez-Cirion: I'm working in an ARCHE collaboration with Nicolas Chomont, with Steve Deeks, with many other researchers from this consortium.

amfAR: What is that whole project about?

Dr. Saez-Cirion: The whole project is meant to better understand how the reservoir is distributed in the different CD4 T cell subsets, which are the subsets that are the most important ones to target with therapy for instance, and the ones that are the most relevant in the persistence of the reservoir.

amfAR: I have just one more question for you. How optimistic do you feel that we'll have a cure for HIV in, say, the next five to 10 years?

Dr. Saez-Cirion: I am optimistic that we will have a cure for HIV, but don't feel ready to say how long that will take us. I think we are making significant steps forward towards an HIV cure. Under the steps we are coming closer and closer every year, but I think we are still a little bit far from a scalable cure for HIV.

Interview with Dr. Ole Søgaard:

Dr. Søgaard: Currently, my research is to pursue the “kick and kill” strategy to see, first of all, if we find a compound or a combination of compounds that effectively activate HIV from latency.

amfAR: Tell us a couple of the different experiments you've done.

Søgaard: In the past, about a year and a half ago, we did an experiment with the HDAC inhibitor panobinostat in 15 HIV patients on antiretroviral treatment. This year, we're starting with a different HDAC inhibitor called romidepsin to see if this agent can also activate HIV from latency—most importantly, if we can measure induction of virus in the plasma of these patients.

amfAR: Can you explain in very simple terms what are you hoping to achieve with HDAC inhibitors?

Søgaard: What we hope to achieve is to have these cells—that lie dormant, but have HIV DNA as part of their own DNA material; to have these cells unmasked to the immune system, so they can be cleared. Because these cells—you can call them silent or resting, non-active cells; these cells are the reason why HIV persists because they don't express, or they don't show, any parts of HIV on their surface, so they are not recognized as being infected by the immune system. What we hope to do with this strategy is to unmask the infected cells to expose them to the immune system and in turn we hope that the immune system will be able to kill the cells to clear them from the body. Ultimately, if this strategy is successful it can be hoped that a large part of the reservoir, or perhaps all of the reservoir, is cleared from the body. A person could be cured of HIV.

amfAR: What role has amfAR played in your research?

Søgaard: amfAR has played actually quite an important role because we've been used to just getting our funding from Danish foundations. With this research we hope to aim for a broader audience, and amfAR has really given us both funding, but also a huge recognition for what we do because, at least in our opinion, getting amfAR funding is also a sign that the research you do is high quality. To us, it has really been a major boost to get recognition from a U.S. independent foundation, rather than from the people we know in Denmark who sit on the different boards of the funders.

amfAR: Great. How optimistic are you that there's going to be a cure for HIV in the next five or 10 years?

Søgaard: That's a tricky question. I'm optimistic that there will be a cure, but I'm not sure that it will be within the next five to 10 years. That's the short version. I think what we realize now, or have been realizing over the past years, is that it's very difficult to cure HIV. Even in patients with no measurable virus in the plasma or within their cells, we still see virus coming out of these very tiny, small reservoirs. I guess in theory you could say one infected cell, one latently masked cell, is enough to restart the infection. So it's very difficult to cure HIV, but I'm optimistic that it will happen sometime in the future.

Interview with Dr. Jan van Lunzen:

Dr. Van Lunzen: Basically we're focusing on two major issues related to HIV cure research at the moment. One is to really find out where are the so-called reservoirs where the virus hides despite effective therapy. We know that these are dormant cells that are infected by the virus, yet we do not know all of the cells where the virus can hide. We do know some of them, but not all of them. And we do not know exactly how and where they are distributed throughout the body. That means that they're at different anatomical sites. We learn a lot from analysis from the blood, but we need to know much more about things from the gut, from the lungs, from other tissues like brain and also lymph nodes because these are the anatomical sites where most likely the virus persists despite very effective therapy.

The second topic we are actually interested in now is to find ways to actually heal the cells from HIV infection. This healing of HIV-infected cells, we are thinking that we may use or get the chance to use so-called nucleases. What are nucleases? Nucleases are basically enzymes which can cut out DNA from cells. Since the provirus, HIV provirus, is integrated in the form of DNA into the host genome, we are trying to exploit these nucleases to cut out the virus out of infected cells. Actually, this works in cell culture. We even know that it works in mice now who are infected by HIV who have been transplanted with a human immune system. However, there is still a long way to go, but we are pursuing this since we believe that the experiences which have been made with the Berlin patient indicate that potential cure is actually possible by using these mechanisms, and this is the second line that we are following.

amfAR: That's interesting. I've never heard anybody use the word “heal” in that setting, but that's a pretty good way to describe it—to take the HIV out of the cells. What are the biggest challenges in your research?

Van Lunzen: First of all I think it is always money. It is money in the sense that we do have a lot of funding that is related to basic research, but as soon as we are going into the clinic, it becomes extensively... the amount of money needed is extended by magnitudes because we have to do proper clinical trials. Clinical trials involving patients are expensive. So this will be one thing. One major issue is clearly funding. There is a lot of funding in the basic research arena, but when it comes up to the translation, the translational part into the clinics, then we have either to find pharmaceutical companies who will supplement it or other funding sources—like amfAR for instance. This is something that is clearly a major issue.

More scientifically, I think as I said, we have learned a lot of things from the peripheral blood of patients with HIV. However, we have to go into the tissues. The tissue is much harder to sample because you cannot do for instance brain biopsies on patients, or you can only take lymph nodes under specific circumstances and also do gut biopsies. So I think we need to learn more about anatomical sites where the virus hides; that we need proper cohorts of patients which we study. It's a kind of passe-partout approach where we use the best characterized patient cohorts, like for instance those who can control HIV after cessation of therapy—so-called post-treatment controllers or elite controllers. What makes them so different from others, especially in the sites where HIV is hiding? And why can those patients actually control HIV infection without therapy, whereas others fail to do so?