On a special episode (first released on September 25, 2024) of The Excerpt podcast: This year, for just the seventh time since the start of the HIV pandemic, a person was cured of the virus. That patient, along with the others cured, had received stem cell transplants to treat another life-threatening disease, blood cancer. But because these transplants carry a significant mortality risk, they’re simply not a viable cure for the roughly 40 million people globally living with the virus. Dr. Sharon Lewin, Professor of Medicine at Doherty Institute at the University of Melbourne, Australia joins The Excerpt to discuss why, in the 40 years since the onset of the HIV pandemic, we still don’t have a cure.
Hit play on the player below to hear the podcast and follow along with the transcript beneath it. This transcript was automatically generated, and then edited for clarity in its current form. There may be some differences between the audio and the text.
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Dana Taylor:
Hello and welcome to The Excerpt. I’m Dana Taylor. Today is Wednesday, September 25th, 2024, and this is a special episode of The Excerpt. This year for just the seventh time since the start of the HIV pandemic, Person, a German man, was cured of the virus. Following stem cell transplants to treat blood cancer, only seven HIV patients have survived the treatment with no viable HIV virus left present in their bodies.
Stem cell transplants are not without risk though. And in the 40 years since the onset of the HIV pandemic, a cure for the roughly 40 million people globally living with the virus remains elusive. Joining us now to discuss why HIV remains such a challenging virus to treat and cure is Dr. Sharon Lewin, Professor of Medicine at Doherty Institute at University of Melbourne Australia. Thanks for being on The Excerpt, Sharon.
Dr. Sharon Lewin:
Thanks very much, Dana.
Dana Taylor:
Stem cell transplants have now been proven to eradicate HIV in the human body. Why is this not a viable treatment for most of those living with HIV?
Dr. Sharon Lewin:
Well, stem cell transplants are actually quite a dangerous procedure, and they’re only done for people that also have a life-threatening illness such as a blood cancer. And that was the case in the seven people that you described who have been cured of HIV. Each of them had a life-threatening blood cancer or leukemia, needed a bone marrow transplant for their blood disease.
And at the same time, the transplant also cured their HIV. So these transplants actually have a mortality of about 20%. So they’re seriously dangerous procedures and they could never be used for someone that doesn’t have a blood cancer. But they have taught us a tremendous amount and shown us that a cure is possible. And we have a number of leads now that can be taken in other forms.
Dana Taylor:
So I do want to get into that. But first, in layman’s terms, can you explain how the HIV virus behaves in the human body?
Dr. Sharon Lewin:
The HIV virus primarily infects one immune cell in our immune system called a T cell. And once it gets inside that cell, it becomes part of the person’s DNA. And when you go on an antiviral treatment, which is actually highly effective for HIV, it will stop the virus replicating inside the cell, but it never gets rid of the virus that’s sitting inside someone’s DNA.
And that’s very different to many other viruses that your viewers or listeners will know about, like COVID-19 doesn’t integrate into the person’s DNA. Therefore, someone that’s on an antiviral treatment has an undetectable viral load, doing very well on treatment, normal health. As soon as they stop the treatment, within two to three weeks on average, the virus rapidly bounces back.
Dana Taylor:
I want to stay with the development of antiviral therapies, and I want to talk about how the prognosis for those living with HIV in 2024 has changed compared to those living with HIV in the 1980s and 1990s. Talk about the progression of these therapies.
Dr. Sharon Lewin:
Yes, we have seen a dramatic change in the treatments for HIV. They’ve become simpler, less toxic, and much easier to take and widely accessible across the world. And antiviral treatment has changed HIV from a death sentence in the early ’80s to people with HIV now having a normal life expectancy. People with HIV on antiviral drugs can safely have babies. They can’t transmit the virus to their sexual partner. The changes have been traumatic.
And then over the last two to three years, we’ve seen even further developments. And that is the option for people with HIV in some countries, not all, to receive their antiviral drugs, not as a tablet, but as an injection currently once every two months should they prefer to have antiviral therapy administered that way. And we’re seeing more and more improvements in delivery modalities, but currently most people around the world would be taking a single tablet a day.
It’s a co-formulated tablet, meaning that inside the tablet there is at least two or three different antivirals and they take that tablet every day and the virus essentially stays under control.
Dana Taylor:
So are we talking about prep? If so, what is it exactly, when is it prescribed, and how does it work?
Dr. Sharon Lewin:
PrEP is something different. PrEP is pre-exposure prophylaxis. It’s to prevent someone from getting HIV, as opposed to antivirals that treat someone already infected with HIV, although the actual drugs are the same. But for PrEP, one can take a single tablet, which contains two antiviral drugs. You take it every day, or you can take it before and after sex, and it will prevent someone from getting infected with HIV and is highly effective if you take it every day.
The big advances in PrEP right now are injectable PrEP. Because just like you can have injectable antivirals to treat the virus, you can also inject these antivirals to prevent. It’s a little bit like contraception. You can either take the pill or you can take an injection. And just recently at the International AIDS Conference in Munich, there was some amazing science presented of a new form of PrEP that can be injected, but now injected every six months.
Dana Taylor:
Are there other emerging technologies, gene editing, vaccines that we should know about?
Dr. Sharon Lewin:
We are seeing a lot of exciting technologies on the horizon for HIV. First are new ways to deliver antivirals, at the moment injections, but one day we may see implants. And gene therapy is really delivering some incredible opportunities for future treatments and cures. They’re not yet available, but you can technically deliver a gene that can insert the right type of antiviral inside your own DNA.
You can insert the gene for an antibody that continues to suppress the virus. So it’s like having a treatment that’s incorporated inside your DNA alongside the virus itself. And those experiments have been done in monkey models and look really quite powerful and effective, meaning that they keep the virus under control. Those experiments have actually been done in human clinical trials as well, but on a very small scale.
And the other approach to gene editing or gene therapy editing is essentially gene scissors. And so you can deliver gene scissors to target the virus itself that’s integrated in a person’s DNA to disable it. And those clinical trials of that form of gene therapy are currently underway in the US.
Dana Taylor:
In terms of new infection rates, where is your greatest area of concern?
Dr. Sharon Lewin:
Most places around the world are doing really well with regard to new HIV infections, and overall new HIV infections are decreasing. However, that’s an average across the world, and some places have got alarming rates of increases of new infections. The places we really worry about are in Eastern Europe and Central Asia, particularly Russia that’s seeing new HIV infections, the Middle East and North Africa and some countries in Asia.
Pakistan and the Philippines are two examples where HIV infections are increasing. Now, you might ask why they’re increasing in some countries and decreasing in many others. In the countries where HIV infections are increasing, this is mainly occurring in countries that have discriminatory laws against people at risk of HIV.
Because if you have a law against how you live, whether you’re gay or you inject drugs or you’re a sex worker, you don’t and can’t access the public health messages that you need to know about how to protect yourself from acquiring HIV or accessing tools such as PrEP.
Dana Taylor:
I was going to bring up the social stigma surrounding HIV infection that’s been hugely detrimental to efforts to stem the spread of the disease. The first HIV diagnosis was more than 40 years ago. Why do you think the harmful stigma still exists?
Dr. Sharon Lewin:
I think stigma still exists because this is a sexually transmitted infection. So many sexually transmitted infections carry stigma. It exists because of the populations that are at greater risk of HIV, such as men who have sex with men, people inject drugs, sex workers. These people undergo stigma and discrimination for other reasons in addition to HIV. But I think if we can get the message out there that HIV is a treatable disease, that people on treatment can’t transmit the virus, there are excellent ways to prevent HIV.
These are all really important messages that can reduce stigma, but it’s still our biggest challenge and may even be more challenge scientifically to overcome than these great hurdles like curing HIV. Stigma is very, very persistent and in some countries remains alarmingly high, quite incredible after such a long period of time and so much understanding about the virus.
Dana Taylor:
According to UNAIDS, in 2023, there are roughly 40 million people globally living with HIV, and approximately 1.3 million people became newly infected that year. What important lessons has the medical community learned from the battle against HIV infection?
Dr. Sharon Lewin:
Well, the medical community have learned the wonders of science, of what science can deliver, which was antiviral therapy. But in order to really make a big impact at a population level and to affect the numbers that you just quoted, you need more than science. You need an engaged community. You need a government that can demonstrate leadership. You need to eliminate stigma and discrimination. You need to eliminate discriminatory laws that worsen public health, don’t benefit public health.
Dana Taylor:
HIV is preventable. What do you see as the best tool in the fight against infection?
Dr. Sharon Lewin:
I think the best tool to prevent new infections is education of communities at risk, access to biomedical prevention strategies as we discussed, PrEP, oral or injectable, finding, testing, treating people with HIV because it reduces the amount of virus that can be transmitted. One tool we don’t have yet is a vaccine, and there’s a lot of debate about whether we even still need an HIV vaccine given all these other tools we now have to prevent infections.
The vaccines by far and away are the cheapest and most effective way to prevent new infections in every other infectious disease. An HIV vaccine is a lot harder, unfortunately, to develop than what we witnessed in COVID. I still remain optimistic that we’ll get there, but the science is going to be tough.
Dana Taylor:
What can the long battle against HIV teach us about addressing public health and future pandemics?
Dr. Sharon Lewin:
The HIV very, very much laid the groundwork for some of the great successes we had in COVID. Firstly, investment in science is really number one. Science can deliver effective diagnostics, effective treatments, and effective vaccines, and that requires deep, deep investment in understanding every of the virus you’re dealing with. And investment in one virus often will pay off in approaches to tackling other viruses, which is exactly what we saw in COVID.
All that investment in HIV treatments and diagnostics and attempt to get a vaccine, a lot of that science was used to accelerate our progress with COVID. But as we learned with HIV and also with COVID, that scientific tools are not enough. You need an engaged community. You need to have fantastically strong, evidence-based, science-driven political leadership, and three of those together, leadership, community, science, this is how we have to tackle current and future pandemics.
Dana Taylor:
The final hurdle to clear would be finding a cure. Are you optimistic that researchers will find a cure for HIV? Where does that stand today?
Dr. Sharon Lewin:
I am optimistic about finding a cure, but again, the science there is tough. We have 37 million people living with HIV currently, all of whom will require long-life treatment. About 78% of people living with HIV are on treatment currently. So we have to find a way to allow people to safely stop their antiviral therapy. And I think we’ve got a few leads that cure is possible, as we discussed earlier with the seven people who had bone marrow transplants.
But we’re also seeing ways that people can control HIV in the absence of antiviral therapy without a stem cell transplant. And that’s largely through using drugs that can enhance the immune control of HIV. Boosting the immune system can in some people allow control. So there’s a lot of work going on around the world in gene therapy, in strategies to reduce the pool of infected cells that persist on treatment to enhance immunity, learnings from the stem cell transplant that I think will deliver a cure one day.
I think the goal of a single-shot cure for everyone, like we have for some bacterial infections, for example, is a long way off. But the science is accelerating. And also as science accelerates in other disciplines such as treating cancer or gene therapy for rare diseases, this gives us more tools to tackle this challenging problem.
Dana Taylor:
Sharon, thank you so much for joining me in this important conversation.
Dr. Sharon Lewin:
It’s been a pleasure, Dana. Thanks for much.
Dana Taylor:
Thanks to our senior producer Shannon Rae Green for production assistance. Our executive producer is Laura Beatty. Let us know what you think of this episode by sending a note to podcasts@.com. Thanks for listening. I’m Dana Taylor. Taylor Wilson will be back tomorrow morning with another episode of The Excerpt.
