amfAR Awards New Funding for Gene Therapy Study Aimed at Curing HIV

-XH4wZag.jpg

Grant supports next phase of three-pronged approach to gene therapy-based cure

NEW YORK, Nov. 6, 2018 --- amfAR, The Foundation for AIDS Research, has awarded $800,000 in new funding to researchers developing an ambitious gene therapy-based approach to curing HIV. The award launches a critical new phase in a study initiated in 2017 with $2.3 million in grants awarded to seven teams of researchers. Six of the teams will move forward with the next phase of the project.

amfAR has forged a unique collaboration among world leaders in gene therapy that began with a think tank in 2016. The amfAR-led meeting gave rise to a plan to create the first combination intervention that will simultaneously address the main barriers to a cure. In a three-pronged attack on the HIV reservoir, the researchers will employ broadly neutralizing antibodies, CAR stem cells—cells genetically reprogrammed to recognize and attack disease cells—and molecular scissors targeting the virus.  

“This is an ambitious and complex project with very exciting potential,” said amfAR Chief Executive Officer Kevin Robert Frost. “It’s a carefully constructed strategy that involves some of the most talented and innovative scientists in the field. We think it holds great promise for developing the scientific basis of a cure by the end of 2020, which is the aim of our Countdown to a Cure for AIDS initiative.”

The researchers will test an approach that combines CAR stem cells that secrete broadly neutralizing antibodies, together with an enzyme (Brec1) that targets HIV DNA in the cell it has infected (while leaving other DNA intact), and long-term secretion of a broadly neutralizing antibody from the liver. The goal is to 1) induce CAR stem cells to kill reservoir cells; 2) to express two different antibodies to neutralize virions (virus that exists outside of cells) in the blood and tissues, and; 3) to use Brec1 to remove the provirus (virus that has been integrated into a cell’s DNA) from infected cells.

The investigators are: Hildegard Büning, Ph.D. (co-principal investigator, molecular biologist, Hannover Medical School, Hannover, Germany), who was recently named president of the European Society of Gene and Cell Therapy;  Keith Jerome, M.D., Ph.D. (co-principal investigator, virologist, University of Washington, Seattle); Hans-Peter Kiem, M.D., Ph.D. (transplantation biologist, Fred Hutchinson Cancer Research Center, Seattle); Scott Kitchen, Ph.D. (molecular biologist, UCLA, Los Angeles); Drew Weissman, M.D., Ph.D. (Immunologist, University of Pennsylvania, Philadelphia); and Richard Wyatt, Ph.D. (immunologist, The Scripps Research Institute, La Jolla).

Timothy Brown (the "Berlin patient") remains the only person known to have been cured of HIV. Brown received a stem cell transplant from a donor with a rare genetic mutation known as CCR5-delta 32, which conferred resistance to HIV infection. Ten years later, he remains free of the virus. 

“While Timothy Brown’s cure was the result of a very different gene therapy intervention, it nonetheless points to the enormous potential of gene therapy as a means of eliminating HIV,” said Dr. Rowena Johnston, amfAR Vice President and Director of Research. “We realize that delivering a gene therapy intervention to HIV-infected people around the world will be a considerable challenge. Part of the mandate of this group of researchers is to design a combination gene therapy intervention that could be effectively delivered by a single injection.”

The grant was supported in part by the Bill and Melinda Gates Foundation.

 About amfAR

amfAR, The Foundation for AIDS Research, is one of the world’s leading nonprofit organizations dedicated to the support of AIDS research, HIV prevention, treatment education, and advocacy.  Since 1985, amfAR has invested more than $517 million in its programs and has awarded more than 3,300 grants to research teams worldwide.

A Novel “Kick and Kill” Strategy to Eliminate HIV

These updates often focus on HIV cure strategies based on methods to eliminate latent reservoirs of HIV infection, the main barrier to a cure. amfAR-funded scientist Dan Barouch of Harvard University, with colleagues from the Ragon Institute, Gilead Sciences, and the University of Massachusetts, now present the results of a study using a novel combination of an immune activator and an HIV neutralizing antibody. The pairing delayed and, in some animals may have eliminated, viral rebound in their monkey model.

 Dr. Dan Barouch

Dr. Dan Barouch

Writing in the October issue of the prestigious journal Nature, Barouch and associates report on 44 monkeys infected with a strain of HIV. This hybrid strain, known as SHIV, contained components of both human and simian immune deficiency viruses.

Beginning on day 7 after infection, all animals received daily antiretroviral therapy (ART) for 96 weeks. They were then divided into four groups: one received nothing; one an antibody (PGT121) capable of neutralizing HIV; one an immune stimulant, vesatolimod (also known as GS-9620), which activates CD4+ T cells and other immune cells including monocytes and natural killer (NK) cells, via a protein known as TLR7; and a final group received both the antibody and the immune stimulant.

ART was continued for another 34 weeks, then stopped. The hope was that vesatolimod would “kick,” or activate, latently infected T cells, rendering them more susceptible to binding by the antibody, and also stimulate monocytes and NK cells to help “kill” infected T cells.

The results were striking.

In all the treated monkeys, the combination of stimulant and antibody delayed time to reappearance of virus after ART was stopped. In those monkeys showing no viral rebound, intensive investigations found no evidence of virus for more than 6 months of follow up.

Given that viral rebound can occur in humans long after stopping ART, the authors cautioned that they “cannot exclude the possibility that exceedingly low levels of virus may still exist in these monkeys.” In addition, ART was begun rapidly—only one week after infection—which is unlikely in the real world of HIV infection. But despite these caveats, the investigators concluded that their experiments provide proof of concept for combining neutralizing antibodies with immune activators in the design of a potential HIV cure.

Dr. Laurence is amfAR’s senior scientific consultant.

Training a Person’s Own T Cells to More Effectively Kill HIV

 Dr. Clio Rooney

Dr. Clio Rooney

CD8+ killer T cells are known to play a critical role in controlling the growth of HIV. But those cells, as produced during the course of an infection, are insufficiently potent to eliminate a persistent HIV infection, regardless of the use of antiretroviral therapy and strategies to induce—or “shock”—HIV from a dormant to an active state.

amfAR-funded scientists Clio Rooney, Cynthia Gay, Catherine Bollard, and David Margolis, working at the University of North Carolina at Chapel Hill and the Children’s National Health System in Washington, DC, along with colleagues from Baylor University, started a clinical trial aimed at overcoming obstacles to T cell-mediated clearance of HIV in ART-treated individuals.

Writing in the October issue of the journal Molecular Therapy, these investigators borrowed a page from the immunotherapy of cancer and certain viral infections. They removed T cells from HIV-infected individuals taking ART, and grew them to very large numbers in the presence of small pieces of HIV protein, immune hormones, and anti-HIV drugs (to prohibit the simultaneous growth of HIV). They then re-infused these “educated” cells—predominantly CD8+ killer T cells and so-called natural killer cells—into their original hosts on two occasions, two weeks apart.

Six subjects ranging in age from 35 to 65, on effective ART for 1 to 9.5 years, underwent this procedure known as adoptive T cell therapy. This first phase of the experiment was structured to evaluate the safety of the procedure. The infusions were well tolerated. As expected based on the study design, there was no change in the size of the latent HIV reservoir. The next step is to combine these infusions with a drug serving as a “latency-reversing agent” capable of inducing HIV growth from latent reservoirs. Such a clinical trial is already underway.

Dr. Laurence is amfAR’s senior scientific consultant.

The Mathilde Krim Effect

 Photo: Annie Leibovitz

Photo: Annie Leibovitz

The September issue of the journal AIDS Research and Human Retroviruses pays tribute to the life and legacy of Dr. Mathilde Krim, amfAR’s Founding Chairman, who died in January. It focuses on amfAR’s Mathilde Krim Fellowships in Basic Biomedical Research, awarded each year to advance the careers of promising young investigators and to invigorate the field of AIDS research, and features new research findings by several recent Krim Fellows.

“On January 15, 2018, the world lost Dr. Mathilde Krim, a woman who changed the life of every person who has ever worked in HIV research,” write Drs. Rowena Johnston and Marcella Flores, amfAR’s Director and Associate Director of Research, respectively, in an introductory essay. The authors go on to describe the extraordinary impact of the Krim Fellowships, now in their tenth year: “What is clear is that the Krim Fellowship program has been a highly successful propagator of exceptional talent.”  

“The Krim Fellowship program has been a highly
successful propagator of exceptional talent.”

amfAR’s Chief Executive Officer Kevin Robert Frost writes: “The cause of human rights was the thread that bound the fabric of Dr. Krim's life, a life defined by an unwavering commitment to the principle that every life was of equal value. She had neither the patience for, nor the interest in, moralizing or philosophizing on the human condition. Dr. Krim celebrated life in all its beautiful diversity, for she loved a colorful world.”

Former Krim Fellow Dr. Nuria Izquierdo-Useros describes Dr. Krim’s unrivaled legacy in advancing the role of women in science. She writes: “The Matilda effect illustrates how the contributions of women to science have been historically attributed to their male colleagues in some circumstances. As a way to overcome the Matilda effect I propose to embrace the Mathilde Krim effect, and commemorate how the will of a woman had such a profound impact on the fight against HIV and AIDS.”

AIDS Research and Human Retroviruses can be found at www.liebertpub.com/toc/aid/34/9

The CHAMP Study: Clues to Natural Control of HIV Infection

In the search for an HIV cure--complete eradication of virus in the absence of ongoing antiretroviral therapy (ART)--one interim strategy involves identification of treatments that can induce sustained suppression of the virus, even if it remains present at very low levels.

 Dr. Steven Deeks

Dr. Steven Deeks

The feasibility of such an approach is greatly strengthened by the existence of a small number of individuals known as post-treatment controllers, who maintain control of HIV growth after discontinuing ART. Writing in The Journal of Infectious Diseases, amfAR-funded scientist Dr. Steven Deeks from the University of California, San Francisco, with colleagues from eight AIDS Clinical Trials Groups (ACTG), identified such individuals and provided insights into their viral control.

In the CHAMP (Control of HIV after Antiretroviral Medication Pause) study, Deeks and colleagues sought to define the frequency of these post-treatment controllers. Reviewing participants in 14 ACTG studies enrolling over 700 individuals, they identified 67 people, of whom 38 were treated during early HIV infection and 25 during its chronic phase. These individuals maintained viral loads less than or equal to 400 copies at least two-thirds of the time after stopping ART, for a minimum of six months of follow-up.

Post-treatment controllers were over three times more prevalent among those who had started ART early in the course of their infection. But most impressive was the durability of HIV control. After one year, 75% still controlled their virus off ART. After five years, 22% still did. Deeks and colleagues also found that the level of virus at which participants in ART interruption trials restarted ART had a dramatic effect on the frequency of post-treatment controllers. Restarting ART at a threshold of 1000 viral copies would have failed to identify about half of those individuals.

The investigators also noted an unusual pattern: one of the 14 ACTG studies reported a surprisingly high number of post-treatment controllers. That study included cycles of ART treatment interruption, suggesting that the concept of “autovaccination,” by which bursts of virus following ART interruption stimulate effective immune responses, should be explored further in HIV cure research.

The authors concluded that “The presence of individuals who can maintain HIV suppression after discontinuing ART provides hope that the goal of sustained HIV remission is possible.”

Dr. Laurence is amfAR’s senior scientific consultant.

Potential New Targets to Block HIV Latency

  Dr. Sharon Lewin

Dr. Sharon Lewin

It’s been known for over two decades that HIV establishes a dormant, or latent, state in CD4+ T cells, in which virus is impervious to the effects of currently available antiretroviral therapies (ART). Multiple subtypes of these T cells can similarly harbor HIV, but it had been assumed that HIV latency occurred when these cells reverted from an activated state to a resting state. Infection of actively growing, proliferating cells was thought to favor productive over latent viral states.

But in a recent issue of the Journal of Immunology, amfAR-funded scientist Sharon Lewin and her colleagues demonstrate that HIV latency can indeed be maintained in actively growing cells. The researchers suggest that this finding may open new avenues to abolish latency.

Lewin and associates used a novel test-tube model, which the team developed, to study the establishment of the HIV reservoir in active and resting CD4+ T cells, simultaneously. The team found that latency was established in both types of T cells but by distinct mechanisms. HIV latency preferentially occurred in a portion of resting T cells through a prolonged interaction with a second cell, the myeloid dendritic cell (mDC). 

Unexpectedly, they found a greater frequency of latent infection in active rather than resting T cells. The active cells bore large amounts of PD-1, a so-called immune checkpoint protein. Blocking its activity is the focus of several new “miracle” anti-cancer drugs, which work for some patients when chemotherapy has failed.

The authors conclude that the means by which HIV induces latency in T cells, and thus evades current cure strategies, may be dependent on interactions with other immune cells such as mDC and immune checkpoint proteins. Overcoming latency therefore “may require targeted therapeutic strategies.”

Dr. Laurence is amfAR’s senior scientific consultant.

 

Sex and the HIV Reservoir

New research points to the powerful effect of estrogen

A newly published study reveals that the female hormone estrogen has a significant effect on the persistent HIV reservoir. It suggests that women may respond differently than men to some curative interventions that are currently under investigation or, perhaps, that an effective cure for women could differ from a cure for men.

 Dr. Jonathan Karn (Photo: Marcus Rose/IAS)

Dr. Jonathan Karn (Photo: Marcus Rose/IAS)

The reservoir of HIV that is impervious to antiretroviral therapy remains the principal barrier to a cure. Following a cohort of 26 men and 26 women, the researchers, led by Dr. Jonathan Karn of Case Western Reserve University, found that women have a smaller “inducible” reservoir than men. In other words, while the total size of the reservoir appears to be the same for both sexes, women have a smaller amount of reservoir virus that can be coaxed out of hiding by so-called latency-reversing agents (LRAs).

The finding has several important implications. First, one of the main cure strategies being pursued by researchers is “shock and kill” (or “kick and kill”). The intent is to shock HIV out of the reservoir so that it can be killed by the immune system or some other killing agent. Given their smaller inducible reservoir, would such a strategy be less effective in women?

Second, since reactivation of the reservoir is inhibited by estrogen, the researchers suggest that “studies of the impact of hormonal contraception on reservoir establishment and its long-term maintenance should be undertaken.”

And, given the small size and exploratory nature of cure-focused clinical studies to date, the inclusion of women in small clinical trials may lead to skewed results if hormone exposure is not considered.

The study concludes that further investigations into sex differences in latency reversal and HIV persistence “are mandatory to extend the benefits of the HIV cure effort to all men and women impacted by the global epidemic.”

Published in the Proceedings of the National Academy of Sciences, these findings are the most recent outgrowth of a multi-year amfAR investigation into sex differences in HIV. “We’ve long known that women and men differ in immune system function and response to antiretroviral therapy, but few researchers have followed up on these leads in cure research,” said amfAR Vice President and Director of Research Dr. Rowena Johnston, a co-author of the study. “It is imperative that we develop a cure that works for everyone.”

In 2012 Dr. Johnston was invited to give a talk on sex differences in HIV cure research at a conference. She soon realized, however, that there were very little available data on the topic. So she teamed up with Dr. Mary Heitzeg of the University of Michigan to undertake a systematic review of more than 150 published HIV cure research studies.

“It is imperative that we develop a cure that works for everyone.” —Dr. Rowena Johnston

The study, published in 2015, found that while there was a strong possibility that the efficacy of a potential cure could vary by demographic variables, only 8% of the studies reported conducting efficacy analyses by sex. They concluded that, “More data are needed to determine associations between demographic characteristics and safety/efficacy of curative interventions.”

Responding to this need, in 2016 amfAR awarded a grant to two teams of researchers led by Dr. Karn and Dr. Eileen Scully of Massachusetts General Hospital to explore how sex-based differences might affect the HIV reservoir and, by extension, a potential cure. The researchers were tasked with comparing the key differences in latent virus in men and women, and exploring the immune profile, activation levels and distribution of latent viral reservoirs in men versus women.

Their first set of findings, detailed in the PNAS paper, lay the groundwork for a preliminary trial to evaluate the effectiveness of the drug tamoxifen combined with the latency-reversing agent vorinostat in reactivating latent HIV in women.  Supported by the National Institutes of Health’s AIDS Clinical Trials Group, the study is expected to conclude in September 2019.  

The CD8 T Cell in HIV: New Insights from Tissue vs. Blood

For obvious reasons, physicians rely on peripheral blood samples to describe the state of the immune system in an HIV-infected individual, and follow the impact of antiretroviral therapies on activity of the virus and immune function. But new data from a large international collaboration that included amfAR-funded scientist Dr. Steven Deeks, suggest that most prior studies, all involving blood, failed to consider a major component of the body’s attack against HIV: the resident memory CD8 T cell, or CD8 TRM.

 Dr. Steven Deeks

Dr. Steven Deeks

Writing in the June issue of Science Immunology, Dr. Deeks, from the University of California, San Francisco, and colleagues* emphasize that the CD8+ killer T cell is required for effective immune control of HIV. However, this type of immune cell exists in three forms. Only two, the central memory and effector memory T cells, circulate in blood. The third form, TRM, resides in lymphoid and non-lymphoid tissues. Yet these TRM cells establish a front line of defense to eliminate invading viruses and bacteria, and do so largely without involvement of circulating CD8 T cells.

Deeks and associates demonstrate that TRM cells dominate the CD8+ killer T cell response against HIV in lymph nodes and other lymph tissue throughout the body. They obtained tissue samples from HIV-infected individuals in the acute and early stages of infection. The highest frequency of these cells was found in “elite controllers,” individuals who maintain very low levels of HIV in the absence of ART.

This discovery has several implications. Importantly, it is known that the potency of certain experimental vaccines against SIV, the simian form of HIV, in monkeys can be predicted from the magnitude of virus-specific CD8 T cells in the lymph tissue of these animals. Expanding knowledge of the activity of the CD8 TRM cells in these tissues should, as the authors conclude, inform “new approaches to the development of vaccines or immunotherapeutic strategies designed to eliminate the viral reservoir in established HIV infection.” In other words, help us reach a cure.

*From the University of Pennsylvania, the Karolinska Institute in Stockholm, the Instituto Nacional de Enfermedades Respiratorias in Mexico City, the National Institutes of Health, the University of Minnesota, Emory University, Case Western Reserve, and Cardiff University in Wales.

Dr. Laurence is amfAR’s senior scientific consultant.

A New Source of Latent HIV?

amfAR-funded researchers continue to study cells other than CD4+ T cells that may harbor latent HIV. Such cells may pose additional obstacles to an HIV cure. Last month’s update featured amfAR grantee Dr. Paula Cannon and her work on specialized cells in the brain. In a study published online in May in The Journal of Clinical Investigation, amfAR grantee Dr. Luis Agosto and colleagues from Boston University look at possible HIV reservoir cells in the vagina.

 Dr. Luis Agosto

Dr. Luis Agosto

Agosto and associates obtained vaginal biopsies from five HIV-negative women and two women with HIV who were receiving antiretroviral therapy. First, they documented that a special type of immune cell, known as a vaginal epithelial dendritic cell (VEDC), could be infected with HIV in the test tube. VEDCs are recognized by their shape, a characteristic internal structure on electron microscopy, and specific cell surface proteins.

But their research went further, showing that these cells were much more susceptible to infection by those strains of HIV that utilize a certain cell surface protein—known as CCR5—to enter a cell, rather than an alternative protein receptor, CXCR4. Based on their findings, the authors suggest that VEDCs may be strict “gatekeepers” for infection, selecting which strains of HIV will establish an infection in a woman.

The researchers also examined the possibility that VEDCs could establish a reservoir of latent virus. They found evidence that this may indeed be a possibility by identifying proviral HIV DNA in VEDCs obtained from the two HIV-positive women. By sequencing the DNA, they established that the VEDCs harbored “ancestral” fragments of HIV (the founder virus that established infection) in the women.

The number of such proviruses per VEDC was four- to eight-fold lower than those found in the women’s blood cells, but the amount was still highly significant. 

More work needs to be done to definitively conclude that vaginal cells are part of the latent HIV reservoir. It is possible that the VEDCs simply scavenged pieces of latent virus from T cells and could not produce infectious viruses when stimulated—the test of a true latent reservoir.

Dr. Laurence is amfAR’s senior scientific consultant.

Neutrophils: A Deadly, if Delicate, Killer

 Dr. Amy Chung

Dr. Amy Chung

Researchers have long focused on natural killer (NK) cells as the principal cells of the immune system that receive a signal via antibodies to kill HIV-infected cells. In the May issue of the Journal of Immunological Methods, amfAR Krim Fellow Dr. Amy Chung and colleagues shed new light on this topic by highlighting the role of neutrophils, a more numerous and much more difficult cell to study, and their less well studied role in killing infected cells via antibodies.

Unlike NK cells, which can persist for years, neutrophils live less than a week inside the body. Outside of the body, they die easily within a few hours and react so quickly to their new environment that, in a petri dish, they no longer resemble the cells the researchers set out to study. While it is known that neutrophils use antibodies to direct their killing ability towards HIV-infected cells, the mechanisms through which they do so remain a mystery.

A neutrophil

To spur this research, Dr. Chung developed a tool to study how antibodies in a patient’s blood might team up with neutrophils. To get around studying the fragile neutrophils in healthy blood, Dr. Chung developed the tool using cells from a cancer patient who donated her cells to science. It was Robert Gallo, one of three scientists credited with discovering that HIV causes AIDS, who archived the cells in 1977. In a petri dish, these cancerous cells can live indefinitely and maintain many of the same characteristics as fresh neutrophils.

Using this tool, Dr. Chung found, surprisingly, that neutrophils were six times better able than NK cells to kill HIV-infected cells when antibodies were present. The authors note that “neutrophil-mediated effector responses should be investigated in future HIV vaccine trials.”

Given what the field is learning about the diverse activities of antibodies (see here and here, for example), there is real potential for neutrophil function to also play an important role in an HIV cure.

Dr. Flores is amfAR’s associate director of research.

HIV in the Brain

 Dr. Paula Cannon

Dr. Paula Cannon

Most studies of the latent HIV reservoir, the primary impediment to a cure, focus on T cells. But amfAR grantee Dr. Paula Cannon, working at the University of Southern California with colleagues there and at Case Western Reserve University, has taken a different approach. She notes that the brain also contains distinct populations of three specialized cells infected with HIV: microglia, astrocytes, and macrophages. She sought to develop a mouse model to study these cells and their role in HIV latency.

Writing in the April issue of the Journal of Neurovirology, Cannon and associates emphasize the difficulty of studying brain cells from HIV-infected humans. In addition, the differences between simian immune deficiency virus and HIV make the monkey a less-than-ideal model for studying HIV in the brain. Instead, she used “humanized mice”—immune deficient animals transplanted with human blood-forming cells. When such cells enter the brain, they transform into just the types of cells thought to harbor the HIV reservoir.

The researchers also focused on a drug, phenelzine (Nardil), currently used to treat depression that doesn’t respond to other medications and able to enter the brain. Phenelzine stimulated HIV production from human microglial cells recovered from the brains of the HIV-infected humanized mice.

The authors felt that their model, and this new form of LRA, or latency reversing agent, shows “great promise as a model system for the development of strategies aimed at defining and reducing the central nervous system [brain] reservoir.”

Dr. Laurence is amfAR’s senior scientific consultant.

Gutting HIV

Very soon after an initial HIV infection, regardless of how it was acquired, HIV homes in on T cells in the gut. It establishes a latent HIV reservoir and, within days, disrupts the normal barrier between intestinal bacteria and the blood. These changes promote a state of chronic inflammation, which in turn fosters HIV growth and spread, and may accelerate disorders associated with aging of the heart, kidney and bone. Antiretroviral therapy (ART) may diminish, but does not stop, these processes.

 Dr. Peter Hunt and Dr. Steven Deeks

Dr. Peter Hunt and Dr. Steven Deeks

Writing in the March issue of the online journal PLoS Pathogens, Drs. Steven Deeks, Peter Hunt and associates from the amfAR Institute for HIV Cure Research at the University of California, San Francisco, and The Wistar Institute in Philadelphia, discovered a new link in this chain of events that may hold the key to promoting intestinal recovery in such individuals.

Using gut biopsies obtained from infected people taking ART, Deeks, Hunt and colleagues found higher levels of A20, a protein associated with reduced inflammation. In the gut biopsies of people not taking ART, on the other hand, A20 levels were reduced. The increase in A20 in those on ART was associated with an increase in three intestinal proteins that support healthy barrier functions of the gut.

But the link between A20 and gut integrity proved to be complex. Using a mouse model of the intestines—an “intestinoid” grown from gut cells in the test tube—they showed that A20 is critical for survival of those cells. But during untreated infection, A20 is suppressed by one element of the immune system’s response to the virus, namely interferon-alpha. The research team confirmed the link between interferon-alpha and A20 by studying the blood cells of HIV-infected individuals on ART who received additional treatment with interferon-alpha.  

Simply put, HIV infection increases the activity of interferon-alpha, which decreases A20 and thus causes harm. Conversely, antiretroviral therapy increases levels of A20, preventing the damage that would otherwise be done to cells in the gut.

The researchers concluded that “variation in A20 expression during the course of HIV infection could underlie both the development of [intestinal] epithelial dysfunction before the initiation of ART and the recovery of intestinal epithelial integrity thereafter…. Further studies are warranted.” Clearly they are, as this may be yet another part of the search for an HIV cure.

 

Dr. Laurence is amfAR’s senior scientific consultant.

 

Can "the Berlin Patient’s" Cure Be Replicated?

amfAR-funded European research consortium aims to find out

When the scientific community learned in a 2009 article in The New England Journal of Medicine that a man known as “the Berlin patient” had been cured of HIV, the news ushered in a new era of HIV research, one underpinned by the knowledge that curing HIV is possible.

But a single person represents an anecdote, and many questions remained unanswered. What are the best ways to measure a vanishingly small amount of virus to confirm that none remains? What were the key elements of his treatment that led to the cure? And most importantly, could this case be replicated?

  Co-Principal Investigators Drs. Javier Martinez-Picado (front right) and Annemarie Wensing (center right), pictured with ICISTEM members including Dr. Gero Hütter, “the Berlin patient’s” physician, and Dr. Maria Salgado. Also pictured are Dr. Rowena Johnston (front, second from right) and Dr. Jeffrey Laurence (back row, right) of amfAR. 

Co-Principal Investigators Drs. Javier Martinez-Picado (front right) and Annemarie Wensing (center right), pictured with ICISTEM members including Dr. Gero Hütter, “the Berlin patient’s” physician, and Dr. Maria Salgado. Also pictured are Dr. Rowena Johnston (front, second from right) and Dr. Jeffrey Laurence (back row, right) of amfAR. 

amfAR addressed the first question by bringing together a team of researchers to intensively study the blood and tissues of Timothy Brown, the Berlin patient, who has been remarkably generous with his body and his time in the service of science. We also brought together another team of researchers to compare every available assay that could quantify low levels of persistent viral reservoir.

amfAR subsequently funded three separate teams to more closely interrogate the circumstances and procedures that led to Timothy Brown’s cure. One of those researchers, Dr. Timothy Henrich, followed the two so-called “Boston patients,” who, after unusually long delays, experienced viral rebound, confirming that their transplants did not cure their HIV infection.

The groundbreaking work conducted by amfAR’s ICISTEM consortium has been recognized by two prestigious awards. Dr. Maria Salgado, a researcher from the IrsiCaixa AIDS Research Institute in Barcelona, Spain, was presented with the inaugural Dominique Dormont Award during the International ADIS Society Conference on HIV Science in Paris in July 2017. And Dr. Jon Badiola of the Virgen de las Nieves University Hospital in Granada, Spain, was presented with a Best Young Abstract Award at the Annual Meeting of the European Society for Blood and Marrow Transplantation in March 2018.

As ever in science, even disappointing results are an opportunity to learn new facts. Scientific findings were increasingly suggesting that the genetic mutation in the donor stem cells that Timothy Brown received were a vital, perhaps even foundational, element of his cure. Another grantee, Dr. Jonah Sacha, concluded that the rejection reaction of the transplanted cells against the recipient’s immune system (known as graft versus host disease) plays a central role in success against cancer and probably also HIV.

In 2012, amfAR began discussions with a group of European researchers with the goal of establishing a research consortium, now known as ICISTEM (www.icistem.org), that could take these questions even further. We chose Europe because it has the highest proportion of people living with the CCR5-delta32 genetic mutation that appears to have been central to Timothy Brown’s cure. The consortium is co-led by the IrsiCaixa AIDS Research Institute in Barcelona, Spain, and the University Medical Center Utrecht in the Netherlands. It includes HIV cure researchers, cancer transplant doctors, and doctors working to register stem cell donors and test their cells for the genetic mutation.

In January, amfAR met with the ICISTEM team in Berlin for an annual progress update and planning session. They have so far enrolled more than 30 patients with cancer and HIV who have received or soon will receive stem cell transplants. And they have identified over two million potential stem cell donors with the CCR5-delta32 mutation.

Most exciting, the group has conducted exhaustive testing for persistent reservoir in many of the transplanted participants and in several cases are unable to find evidence that any HIV remains. They are preparing to embark on the next phase of this scientific journey, the definitive test of a cure, namely the withdrawal of antiretroviral therapy. Results will take at least a year, and while we cannot promise that any of these people will be shown to be cured, we can promise that amfAR is pursuing every promising avenue to discover what it will take to finally cure HIV.

Dr. Johnston is an amfAR Vice President and Director of Research.

New Findings Point to Power of Antibodies

New research by amfAR grantee Dr. Dan Barouch and colleagues at Beth Israel Deaconess Medical Center in Boston further supports the idea that an HIV cure is likely to require a combination of agents rather than just one. It also offers further evidence of the potential role of antibodies in curing HIV.

 Dr. Dan Barouch

Dr. Dan Barouch

Barouch’s study involved a group of macaque monkeys infected with SHIV, a combination of HIV and SIV (the simian form of the virus). The researchers found that those monkeys that had been given a broadly neutralizing antibody called PGT121 combined with an immunotherapeutic drug that may act as a latency-reversing agent experienced a significant delay to viral rebound after being taken off antiretroviral treatment. They also rebounded to lower levels of virus. 

While the findings are extremely encouraging, the researchers cautioned that the results are very preliminary in relation to a cure for HIV. Dr. Barouch reported on his findings at the 2018 Conference on Retroviruses and Opportunistic Infections in Boston in February.

In a previous study reported in the August 2017 issue of the Journal of Virology, Dr. Barouch, along with colleagues from the Ragon Institute of MGH, MIT, and Harvard in Cambridge, MA, the National Institutes of Health in Bethesda, MD, and Leidos Biomedical Research and Frederick National Laboratory Center for Cancer Research in Frederick, MD, used a “passive immunization” approach to explore the potential role of antibodies in curing HIV infection.

This study also involved monkeys infected with SHIV. The monkeys were treated with either PGT121 or another antibody know to have anti-HIV properties called N6, a combination of both, or a placebo. The antibodies reduced the viral load in the monkeys.

The researchers then measured SHIV DNA in the blood and lymph nodes to see if the antibodies had any effect on infected cells. They found significantly reduced levels of SHIV DNA in the blood two weeks after the antibodies were administered; in the lymph nodes, SHIV DNA dropped markedly after 10 weeks.

These results suggest that passive immunization using these antibodies might, under the right conditions, kill cells of the persistent viral reservoir and thus play a role in curing HIV.

A Potential New Target for Eradication of HIV Reservoirs

In the January update we featured research led by amfAR-funded scientists at Case Western Reserve University on an FDA-approved drug, ruxolitinib, used in the experimental treatment of lymphoma. Writing in the February issue of the journal PLoS Pathogens, Drs. Timothy Henrich and colleagues at the amfAR Institute for HIV Cure Research at the University of California, San Francisco, and at Harvard University, continue this concept of evaluating anti-cancer drugs in anti-HIV strategies.  

 Dr. Timothy Henrich

Dr. Timothy Henrich

The investigators studied the FDA-approved drug brentuximab (Adcetris). It is a toxin linked to a monoclonal antibody in order to target the activity of that toxin to cells that express the molecule CD30 on their surface. The drug is an important part of the treatment of resistant Hodgkin disease, a type of cancer, and certain other types of aggressive lymphoma. Fortunately, its target is highly expressed on certain tumor cells, but on only a very small percentage of normal cells. Dr. Henrich and his colleagues took advantage of the fact that other researchers had reported high levels of CD30 in patients with untreated HIV infection.

Henrich and colleagues now document that HIV is highly enriched in CD4+ T cells expressing CD30 obtained from HIV-infected individuals, regardless of whether or not they are on suppressive antiretroviral therapy (ART). Furthermore, exposure of T lymphocytes obtained from these individuals to brentuximab in the test tube reduces the amount of HIV DNA—a measure of virus reservoir size.

Their studies also addressed the question of HIV reservoirs in tissue. Active HIV in gut samples obtained from some of the patients was concentrated in CD30 positive cells.

Bringing this research back to the patient, the investigators studied an HIV-infected individual given brentuximab for his lymphoma. He had no detectable virus in his blood after six cycles of treatment. This was unexpected, as HIV-infected individuals receiving other types of chemotherapy do not lack detectable HIV. Although brentuximab has serious side effects and must be given as an intravenous infusion, limiting its applicability for HIV-positive individuals who don’t require it for cancer treatment, the authors rightly conclude that “CD30 is a potential therapeutic target of persistent HIV-1 infection.”  


Dr. Laurence is amfAR’s senior scientific consultant.

Progress Toward a Better “Shock and Kill”?

amfAR-funded scientist Dr. Brad Jones of George Washington University in Washington, DC, has discovered an obstacle to the “shock and kill” strategy for curing HIV that may have implications for the success of this approach in the clinic.

“Shock and kill” involves using drugs to “shock” latent virus out of hiding so that it can be killed by the immune system or interventions such as a therapeutic vaccine or broadly neutralizing antibodies. In the February issue of The Journal of Clinical Investigation, Jones and colleagues report that the latent HIV reservoir resists attack by CD8 T cells, immune cells charged with clearing virally infected cells.

 Dr. Brad Jones

Dr. Brad Jones

The authors note that shortly after a person becomes infected, HIV begins to accumulate mutations. As a result, over 88% of viral genes are so defective they are unable to produce infectious virus. However, the reservoir makes up a tiny fraction of the remaining 12% of infected cells and harbors intact genomes capable of producing infectious virus.

Previous ”shock and kill” strategies aimed to reawaken this latent reservoir with drugs called latency-reversing agents (LRAs) to expose the infected cells to the killing power of the immune system. (View amfAR’s explanatory video here.) However, Jones’s research shows that even after reactivation of the reservoir, CD8 T cells prefer to kill cells infected with defective virus and thus have little effect on the reservoir. Even more intriguing, the scientists found evidence to suggest that the reservoir cells, when attacked by CD8 T cells, somehow shield themselves from their deadly onslaught.

At a December scientific conference in Miami, Jones presented related findings pointing to a drug that could make the reservoir more susceptible to killing in a “shock and kill” context. In this “prime, shock and kill” strategy, a drug is given to the patient to prime, or prepare, the reservoir to submit to being killed by CD8 T cells. Then, just as with “shock and kill,” LRAs are added to reawaken the reservoir and mark those cells for killing by the immune system.

“Overall,” Jones said, “I remain very optimistic about “shock and kill” … I just think we may be missing an extra piece of the puzzle. We may have more success with ‘prime, shock and kill.’”

While more work needs to be done to improve “shock and kill,” such as developing more potent LRAs, Jones’s findings could help improve the effectiveness of this strategy.

Dr. Flores is amfAR’s associate director of research. 

amfAR Renews Investment in Bioengineering Approaches to Curing HIV

amfAR, The Foundation for AIDS Research, today announced a pair of research grants that renew its support for innovative approaches to HIV cure research. Totaling nearly $1 million, the Investment grants will allow two collaborative teams of HIV researchers and bioengineers to embark on a second phase of projects initiated with amfAR funding awarded in February 2017. 

Transmitting HIV (in the Test Tube) Despite Antiretroviral Therapy

During initial infection with HIV from anal or vaginal intercourse, a type of immune cell known as a dendritic cell (DC) is the first component of the immune system to encounter the virus at mucosal surfaces. Such surfaces protect the body from viruses and bacteria. DCs can migrate to lymph nodes and similar tissues, where contact with T cells may then play a key role in spreading the virus. This process, known as “trans infection,” occurs despite the fact that DCs themselves cannot be directly infected with HIV.

 Dr. David Baltimore

Dr. David Baltimore

In the January issue of the journal PLOS ONE, amfAR grantee and Nobel Prize laureate Dr. David Baltimore of Caltech in Pasadena, CA, with colleagues from the University of California, Los Angeles, the Max Planck Institute for Infection Biology in Berlin, and the Africa Health Research Institute in Durban, South Africa, examines this process in the test tube.

The investigators found that DCs can transmit HIV to T cells by direct contact despite the presence of two very potent anti-HIV drugs: the reverse transcriptase inhibitor tenofovir and the integrase inhibitor raltegravir. This was dependent on the number of DCs contacting a T cell and the amount of virus present in the body.

Researchers also discovered that DCs may increase the probability of establishing an HIV infection not only by transporting the virus, but also by amplifying the number of cells it can infect. DCs also reduce the anti-HIV potency of drugs. The latter is of particular concern in lymph nodes, which may have lower drug levels than in the blood and other tissues. It also has implications for HIV cure strategies.

The authors conclude: “Transmission of HIV by DCs in trans may have important implications for viral persistence in vivo in environments where residual replication may persist in the face of antiretroviral therapy.”

Dr. Laurence is amfAR’s senior scientific consultant. 

Cancer Drug Leads to ‘Drastic Decrease’ of HIV Reservoir in Patient

A team of French doctors observed a “drastic and persistent decrease” of the HIV reservoir in a lung cancer patient given a drug commonly used to treat several cancers in their advanced stages.

The reservoir is the collection of HIV-infected cells that persists despite antiretroviral drugs and hides under the radar of the immune system. It is the wellspring of HIV that quickly rebounds when treatment is stopped.

“This is the first case of such a drastic decrease of the HIV reservoir,” said Dr. Jean-Philippe Spano, head of the medical oncology department at Pitié-Salpêtrière Hospital in Paris where the patient was treated. But, he cautioned, “we must remain careful, especially because this is only one case.” Spano and his colleagues detailed the case last month in a letter published in Annals of Oncology.

 Dr. Jean-Philippe Spano

Dr. Jean-Philippe Spano

The 51-year-old man was given nivolumab (marketed as Opdivo) once every two weeks starting in December 2016 after he relapsed following surgery and chemotherapy for his tumor. Nivolumab has been shown to be effective in treating melanoma, non-small cell lung cancer, and kidney cancer.

When the patient started treatment, his viral load was undetectable. It steadily climbed until day 45 before falling again. During that time, the activity of his T cells also increased. By day 120, he had experienced "a drastic and persistent decrease" in HIV reservoir levels, the researchers said.

Doctors believe the cancer drug may have enhanced the “killing” of HIV-infected cells by releasing the brakes the immune system deploys for safety. However, they noted that another HIV-infected patient given the same treatment did not experience a reduction in the reservoir.

Still, the findings “could have implications for HIV patients, both with and without cancer, as it can work on HIV reservoirs and tumor cells independently," Spano said. “The absence of side effects in this patient is also good news and suggests this could be an optimum treatment for HIV-infected patients with cancer."

Commenting on the study for HealthDay, Dr. Marcella Flores, amfAR’s associate director of research, called the case “interesting and hopeful.” However, she noted that while the drug caused a substantial decrease of the HIV reservoir, it did not completely eradicate the virus.

She told the news service that more work needs to be done to better understand this particular patient's experience and to figure out how it might help others.

See also: https://www.sciencedaily.com/releases/2017/11/171130214929.htm