Using Groundbreaking CAR-T Cancer Therapy to Eliminate HIV

On August 30, 2017, the U.S. Food and Drug Administration approved Kymriah as the first gene therapy for patients with a drug-resistant form of acute leukemia. The chimeric antigen receptor (CAR) therapy involves modifying a patient’s own T cells to seek and destroy cancer cells. It is a one-time treatment, and for many people, a lifesaving one. The approval of this therapy received worldwide publicity. But what may come as a surprise to many is the critical role HIV research played in the development of Kymriah, and how this proof-of-concept treatment for cancer relates to progress toward an HIV cure.

Dr. Scott Kitchen

Writing in the September issue of the journal Translational Research, amfAR-funded scientist Dr. Scott Kitchen and colleagues from the University of California, Los Angeles note that most investigators believe that enhancing a person’s natural immune response will be key in eliminating HIV-infected cells. Indeed, HIV-specific CD8+ killer T cells can be engineered to inhibit HIV growth and reduce the size of the HIV reservoir in the test tube. But this strategy has numerous drawbacks, including the need to alter HIV killer cells based on an individual’s HLA tissue type. CARs are based on engineering CD4+ T cells, which don’t have that requirement. Almost all HIV-infected patients can be treated with the therapy, regardless of genetic makeup.

The researchers explain that the first CAR T cells to be used in clinical trials were actually designed and tested for the treatment of HIV—not cancer. In addition, in order to enable those cells to recognize infected cells, a self-inactivating lentivirus—a modified form of HIV—was used to introduce the necessary genes. However, pilot trials showed less than satisfactory results, as unlike cancer, HIV can attack the very CAR T cells administered to fight the infection. With this in mind, Kitchen and associates discuss several novel approaches to enhance the activity of anti-HIV CAR T cells and to protect them against infection.

These strategies include removing, through genetic engineering, the primary HIV co-receptor CCR5. (The “Berlin patient” became the first person to be cured of HIV after receiving a stem cell transplant from a donor with a CCR5 mutation.) The scientists also propose a combination approach to kill infected cells and eliminate latent HIV reservoirs.

The authors conclude: “CAR-based therapy for HIV infection is becoming a promising approach to provide lifelong immune surveillance and viral suppression without the use of antiretroviral therapy … a closer step toward a functional cure for HIV.”

Dr. Laurence is amfAR’s senior scientific consultant. 

Injection of Specific Antibodies May Reduce HIV Viral Load

While the role of antibodies in preventing infection is clear, a growing number of researchers are enlisting antibodies to help cure HIV. One of the most promising avenues to achieve this is passive immunization, in which antibodies are injected directly into the patient.

Dr. Dan Barouch

In the August issue of the Journal of Virology, amfAR-funded scientist Dr. Dan Barouch of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston, 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, uses a passive immunization approach to explore the potential role of antibodies in curing HIV infection.

Barouch and associates tested two antibodies, PGT121 and N6, in 18 monkeys infected with SHIV, a combination of HIV and SIV (the simian form of the virus). Both PGT121 and N6 are known to be active against HIV. The monkeys were treated with either PGT121 or 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. The authors note that the monkeys’ naturally occurring antibodies and immune responses to SHIV were not enhanced as a result of the PGT121 or N6 infusions, arguing against their contribution to the observed viral effects.

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 Gene Therapy Revolution?

New amfAR gene therapy grants awarded as FDA panel recommends approval of first ever gene therapy-based treatment in the U.S.

On July 12, a Food and Drug Administration panel for the first time recommended approval in the U.S. of a gene therapy-based treatment. The treatment, first developed by Dr. Carl June of the University of Pennsylvania, a member of amfAR’s Cure Council, is based on the use of so-called CAR cells to kill cancer cells.  

On July 13, amfAR announced two new grants to research teams pursuing similar strategies involving CAR (chimeric antigen receptor) cells, which have shown significant potential for their ability to kill HIV-infected cells. The grants are part of a new round of seven awards totaling $2.3 million in support of gene therapy-based approaches to curing HIV.  They were awarded through the amfAR Research Consortium on HIV Eradication (ARCHE), a program that fosters collaboration among teams of scientists. 

“Curing HIV is no longer a pipe dream, and the case of ‘the Berlin patient’ provides proof-of-principle that a cure is possible. However, several complex scientific challenges remain, and these new grants reflect amfAR’s determination to pursue a range of strategies to overcome them.”

CAR Cells and Cure

Scott Kitchen, Ph.D., of University of California, Los Angeles, plans to improve the effectiveness of CAR cells at killing HIV-infected cells by increasing their ability to detect the appropriate target cells and prolonging their survival. He also plans to engineer improvements to minimize the loss of CAR cells to attack by the immune system, and to design a mechanism to “switch off” CAR cells should they become unsafe or are no longer needed.

And a team led by Richard Wyatt, Ph.D., of The Scripps Research Institute in La Jolla, CA, plans to generate CAR T cells with the ability to kill HIV-infected cells just as they begin to produce virus. Additionally, the CAR T cells will be engineered to produce antibodies that may destroy virus and the cells that produce it.

The other grantees are: Hildegard Büning, Ph.D., of Hannover Medical School in Hannover, Germany; Keith Jerome, M.D., Ph.D., of University of Washington in Seattle; Hans-Peter Kiem, M.D., F.A.C.P., of Fred Hutchinson Cancer Research Center, Seattle; Yasuhiro Takeuchi, Ph.D., of University College London, United Kingdom; Drew Weismann, M.D., Ph.D., of University of Pennsylvania, Philadelphia.

Genetic Scissors 

The researchers will pursue projects aimed at: designing and refining vectors that can accurately target the cells that make up the reservoir and regions such as the lymph nodes, where the reservoir cells tend to be concentrated; and exploring the potential of using viral and non-viral delivery mechanisms to deliver emerging types of genetic scissors that could cut the virus out of human DNA.

“Curing HIV is no longer a pipe dream, and the case of ‘the Berlin patient’ provides proof-of-principle that a cure is possible,” said amfAR Chief Executive Officer Kevin Robert Frost, referring to the only person known to have been cured of HIV. “However, several complex scientific challenges remain, and these new grants reflect amfAR’s determination to pursue a range of strategies to overcome them.” 

New Innovation Grants

In a second round of grants, amfAR awarded $1.2 million to six researchers who will explore mechanisms of HIV persistence and the potential for HIV eradication. These “Innovation” grants are designed to test and advance innovative ideas in the early stages of testing.

“Through these projects, we will continue to forge the scientific alliances − within HIV and beyond − that we believe are our best hope for accelerating progress toward a cure.”

For instance, Andrew Badley, M.D., from the Mayo Clinic College of Medicine in Rochester, MN, will test whether ixazomib, a drug currently used to treat the blood cancer multiple myeloma, can reduce the size of the viral reservoir in the body. Joshua Schiffer, M.D., from Fred Hutchinson Cancer Research Center in Seattle, WA, will test a drug normally used to prevent organ transplant rejection for its potential to eliminate the persistent HIV reservoir.

Andrew Henderson, M.D., from Boston University School of Medicine in Boston, MA, and Fabio Romerio, Ph.D., from University of Maryland, Baltimore, MD, will both explore a cure strategy known as “block & lock,” which aims to permanently silence HIV and prevent the emergence of virus when antiretroviral therapy is stopped.

Brad Jones, Ph.D., from The George Washington University, Washington, DC, aims to develop a new class of broadly neutralizing antibodies that enable the immune system to recognize proteins not normally accessible to the body’s antibody making machinery. The goal is to increase the number of people in whom broadly neutralizing antibodies are able to find and kill HIV-infected cells.

Berlin Patient

And to better understand how Timothy Brown, “the Berlin patient,” was cured of HIV, Benjamin Burwitz, Ph.D., from Oregon Health and Science University in Portland, will explore the precise mechanisms that led to his cure by generating a monkey model lacking the protein CCR5, the primary means by which most types of HIV infect cells.

“These two rounds of grants get to the heart of the scientific challenges we face in our search for a cure,” said Dr. Rowena Johnston, amfAR’s vice president of research. “Through these projects, we will continue to forge the scientific alliances − within HIV and beyond − that we believe are our best hope for accelerating progress toward a cure.” 

Learn more about the ARCHE and Innovation grants.

• Press Release: New amfAR Research Grants Advance Gene Therapy and Other Innovative Approaches to HIV Cure

New amfAR Research Grants Advance Gene Therapy and Other Innovative Approaches to HIV Cure

More than $3.5 million awarded to researchers
aiming to overcome barriers to curing HIV 

NEW YORK, NY, July 13, 2017 – amfAR, The Foundation for AIDS Research, has awarded more than $3.5 million for 13 new research grants to support innovative approaches to depleting or eliminating the persistent reservoirs of HIV not cleared by antiretroviral therapy – considered the main barrier to a cure. The grants represent the latest investments in the Foundation’s Countdown to a Cure for AIDS initiative, which is aimed at developing the scientific basis of a cure by the end of 2020. To date, amfAR has awarded Countdown grants totaling close to $42 million to support research conducted by more than 222 scientists working at 74 institutions in 10 countries around the world.

“Curing HIV is no longer a pipe dream, and the case of ‘the Berlin patient’ provides proof-of-principle that a cure is possible,” said amfAR Chief Executive Officer Kevin Robert Frost, referring to the only person known to have been cured of HIV. “However, several complex scientific challenges remain, and these new grants reflect amfAR’s determination to pursue a range of strategies to overcome them.”  

Through the amfAR Research Consortium on HIV Eradication (ARCHE), a program that fosters collaboration among teams of scientists, more than $2.3 million in grants was awarded to seven teams of researchers working on gene therapy-based approaches to curing HIV. While pharmacological and immunological approaches remain the dominant cure strategies, the Berlin patient’s cure involved a procedure that points to the promise of gene therapy.

The grantees are: Hildegard Büning, Ph.D., of Hannover Medical School in Hannover, Germany; Keith Jerome, M.D., Ph.D., of University of Washington in Seattle; Hans-Peter Kiem, M.D., F.A.C.P., of Fred Hutchinson Cancer Research Center, Seattle; Scott Kitchen, Ph.D., of University of California, Los Angeles; Yasuhiro Takeuchi, Ph.D., of University College London, United Kingdom; Drew Weissman, M.D., Ph.D., of University of Pennsylvania, Philadelphia; and Richard Wyatt, Ph.D., of The Scripps Research Institute in La Jolla, CA.

Gene therapy offers the tantalizing possibility of manipulating DNA as a means of attacking infected cells that make up the HIV reservoir, altering the susceptibility of cells to HIV infection, or enhancing the ability of the immune system to attack or block the virus. But it carries a number of risks and challenges. Scientists need to find ways to improve the efficiency of appropriately altering DNA, effectively target the correct cells, and enable the therapy to safely persist long enough to have an effect.

The researchers will pursue projects aimed at: designing and refining vectors that can accurately target the cells that make up the reservoir and regions such as the lymph nodes, where the reservoir cells tend to be concentrated; using so-called CAR T cells, which have shown remarkable promise in clearing some types of cancer, as a potential means of killing HIV-infected cells; and exploring the potential of using viral and non-viral delivery mechanisms to deliver emerging types of genetic scissors that could cut the virus out of human DNA.

In a second round of grants, amfAR awarded $1.2 million to six researchers who will explore mechanisms of HIV persistence and the potential for HIV eradication. These “Innovation” grants are designed to test and advance innovative ideas in the early stages of testing.

For instance, Andrew Badley, M.D., from the Mayo Clinic College of Medicine in Rochester, MN, will test whether ixazomib, a drug currently used to treat the blood cancer multiple myeloma, can reduce the size of the viral reservoir in the body. Joshua Schiffer, M.D., from Fred Hutchinson Cancer Research Center in Seattle, WA, will test a drug normally used to prevent organ transplant rejection for its potential to eliminate the persistent HIV reservoir.

Andrew Henderson, M.D., from Boston University School of Medicine in Boston, MA, and Fabio Romerio, Ph.D., from University of Maryland, Baltimore, MD, will both explore a cure strategy known as “block & lock,” which aims to permanently silence HIV and prevent the emergence of virus when antiretroviral therapy is stopped.

Brad Jones, Ph.D., from The George Washington University, Washington, DC, aims to develop a new class of broadly neutralizing antibodies that enable the immune system to recognize proteins not normally accessible to the body’s antibody making machinery. The goal is to increase the number of people in whom broadly neutralizing antibodies are able to find and kill HIV-infected cells.

And to better understand how Timothy Brown, “the Berlin patient,” was cured of HIV, Benjamin Burwitz, Ph.D., from Oregon Health and Science University in Portland, will explore the precise mechanisms that led to his cure by generating a monkey model lacking the protein CCR5, the primary means by which most types of HIV infect cells.

“These two rounds of grants get to the heart of the scientific challenges we face in our search for a cure,” said Dr. Rowena Johnston, amfAR’s vice president of research. “Through these projects, we will continue to forge the scientific alliances - within HIV and beyond - that we believe are our best hope for accelerating progress toward a cure.”

Click here for full descriptions of the ARCHE and Innovation grants.

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 the advocacy of sound AIDS-related public policy. Since 1985, amfAR has invested more than $480 million in its programs and has awarded grants to more than 3,300 research teams worldwide.

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ARCHE Gene Therapy Grants

July 2017

Hildegard Büning, Ph.D. – principal investigator
Hannover Medical School, Hannover, Germany
$386,578 (109570)
Vector-mediated in vivo targeting of HIV reservoir cells or provirus elimination: To maximize safety of gene therapy, methods to specifically target reservoir cells are required. The HIV reservoir consists mainly of CD4+ T cells, with certain subsets more commonly harboring latent HIV. Dr. Büning plans to design an adeno-associated viral vector that specifically targets one of these main subsets, the central memory T cells. The vector will be designed to carry a gene editing tool called Brec1, previously shown to suppress HIV. One reported advantage of Brec1 over other gene editing tools is the apparent lack of off-target effects. 

Keith Jerome, M.D., Ph.D. – principal investigator
University of Washington, Seattle, WA
$399,955 (109575)
Subcutaneous administration of DARPin-modified adeno-associated virus vectors for selective targeting of CD4+ T cells: Curing a diffuse disease such as HIV, as opposed to a localized tissue-specific disease, requires a way to target the gene therapy to the target cells of interest, which in HIV are dispersed throughout the body. Dr. Jerome plans to use adeno-associated viral virus vectors engineered to utilize small, antibody-like  proteins to target the vectors and their gene-editing cargo directly to CD4+ T cells, which comprise the majority of the HIV reservoir. He will also experiment with ways of infusing the vectors such that they preferentially reach the lymph nodes, where most reservoir cells are found.

Hans-Peter Kiem, M.D., F.A.C.P. – principal investigator
Fred Hutchinson Cancer Research Center, Seattle, WA
$200,000 (109608)
Engineering blood cells to produce broadly neutralizing anti-HIV antibodies: Antibodies have been the focus of increasing optimism in the HIV cure research field due to their ability to not only neutralize virus particles, but also to target and help kill infected cells. Dr. Kiem plans to genetically modify immune system progenitor cells to serve as a constant source of antibodies. By engineering cells that will differentiate into a variety of types of immune cells, Dr. Kiem hopes that the progeny cells will migrate to various parts of the body, including lymph nodes and brain known to be important reservoirs of HIV.

Scott Kitchen, Ph.D. – principal investigator
University of California, Los Angeles, Los Angeles, CA
$400,000 (109577)
Optimized efficacy and persistence of engineered HIV-specific cellular immunity: Chimeric antigen receptor (CAR) cells have shown remarkable promise in their ability to clear some cancers in patients, and additionally have shown potential in HIV cure. Dr. Kitchen plans to improve the ability of CAR cells to kill HIV-infected cells by increasing their ability to detect the appropriate target cells and prolonging their survival. He also plans to engineer improvements to minimize the loss of CAR cells to attack by the immune system, and to design a mechanism to “switch off” CAR cells should they become unsafe or are no longer needed.

Yasuhiro Takeuchi, Ph.D. – principal investigator
University College London, London, United Kingdom
$360,034 (109584)
LentiStim: Mass production of lentiviral vectors for in vivo gene delivery: Curing HIV by gene therapy may require long-term persistence of the gene editing tools delivered by lentiviral vectors, which are closely related to HIV. Because the reservoir that harbors persistent HIV consists almost entirely of resting cells, such vectors cannot gain entry into the cells to deliver their cargo. Dr. Takeuchi plans to modify lentiviral vectors with a cocktail of stimulatory molecules that induce an optimal level of activation in the target cell, thus allowing entry of the vector. The effectiveness of lentiviral vectors is also plagued by immune responses raised against the vector, so the team will produce vectors that are resistant to destruction by the immune system.

Drew Weissman, M.D., Ph.D. – principal investigator
University of Pennsylvania, Philadelphia, PA
$400,000 (109587)
Targeting of nucleic acid therapeutics to cure HIV: Gene therapy approaches to cure HIV include efforts to cut the virus out of the human DNA, or to imbue the human host cells with characteristics that protect them from infection. Dr. Weissman plans to employ nucleic acid therapeutics as the tools to edit DNA to achieve either or both of these goals. One advantage of nucleic acid therapeutics is the ability to administer them repeatedly without raising an immune response that would destroy them. He plans to optimize their delivery to the appropriate cells by packaging them inside lipid nanoparticles that can be engineered with surface particles that guide them to specific targets.

Richard Wyatt, Ph.D. – principal investigator
The Scripps Research Institute, La Jolla, CA
$199,362 (109618)
Vector-mediated in vivo targeting of HIV reservoir cells or provirus elimination: Chimeric antigen receptor (CAR) cells have shown remarkable promise in their ability to clear some cancers in patients, and additionally have shown potential in HIV cure. One advantage is their ability to overcome a cancer or virus-infected cell’s ability to hide from the immune system. Dr. Wyatt plans to generate CAR T cells with the ability to kill HIV infected cells just as they begin to produce virus. Additionally, the CAR T cells will be engineered to produce antibodies that can neutralize any virus that is produced.

Innovation Grants 2017

PI: Andrew Badley, MD
Mayo Clinic College of Medicine, Rochester, MN
$200,000 (#109593)
Ixazomib to reduce HIV reservoir size: Cells have a recycling mechanism that disposes of or reuses old proteins—the proteasome. If the proteasome is disrupted, these damaged proteins persist, clogging up the cell and eventually leading to cell death. Ixazomib is a drug that is currently used in multiple myeloma, a form of blood cancer. Dr. Andrew Badley proposes to conduct a clinical study to test the ability of the drug to reduce the viral reservoir, the main barrier to a cure. 

PI: Benjamin Burwitz, PhD
Oregon Health and Science University, Portland, OR
$199,948 (#109596)
Creation of CCR5 knockout Mauritian cynomolgus macaques for stem cell transplants:
The Berlin patient, the first and only patient so far to have been cured of HIV, received a stem cell transplant from a donor who was genetically resistant to HIV because the donor lacked a key HIV receptor, the protein CCR5.  The Berlin patient’s difficult medical history and complications have made it difficult to determine exactly what led to his cure: was it the stem cell transplant, the complications presented by his new immune system attacking HIV-infected cells as part of a transplant complication known as graft vs. host disease, the chemotherapy and radiation used in the transplant, or some combination of these? Dr. Benjamin Burwitz proposes to answer these questions by generating a monkey model lacking CCR5, enabling him to test the multiple hypotheses concerning the Berlin patient’s cure.

PI: Andrew Henderson, PhD
Boston University School of Medicine, Boston, MA
$200,000 (#109603)
Disabling HIV provirus by promoting chromatinization: CRISPR/Cas9, a protein complex recently discovered in bacteria, has revolutionized biology because of the flexibility and ease with which scientists can use it to target and edit DNA, cutting out unwanted pieces, including the DNA form of HIV. Dr. Andrew Henderson is proposing to use this protein complex to silence the HIV DNA in a so-called “Block & Lock” approach. Unlike “Shock & Kill”, which requires the cell to wake up from latency- a formidable challenge - “Block & Lock” would permanently silence HIV and prevent the emergence of virus when ART is stopped.

PI: Brad Jones, PhD
The George Washington University, Washington, DC
$199,998 (#109606)
HLA-E specific TCR-like Antibodies for the Universal Targeting of Persistent HIV Reservoirs: Broadly neutralizing antibodies that target the viral protein Env—the only viral protein expressed on the surface of infected cells - must circumvent the high mutation rate of Env in order to be effective. On the other hand, viral proteins present inside the cell are much less subject to mutation but are poorly accessible to our body’s antibody making machinery. Because of a newly discovered immune mechanism, scientists have now found that the internal viral proteins may be digested and displayed on the surface of cells in a molecule called HLA-E. Dr. Brad Jones proposes to engineer antibodies that will recognize the digested protein/HLA-E complex and make the cell susceptible to death by Natural Killer cells.

PI: Fabio Romerio, PhD
University of Maryland, Baltimore, MD
$199,999 (#109612)
Permanent Silencing of HIV-1 Expression through the Polycomb Repressor Complex 2 epigenetic pathway: Dr. Fabio Romerio has uncovered a unique mechanism through which HIV drives its own latency, namely by making a molecule called Ast. He proposes that Ast participates in actively preventing the viral DNA from making virus. Dr. Romerio aims to determine how Ast asserts its effect and whether it can be delivered to all HIV infected cells to permanently and specifically block viral DNA. In contrast to the curative approach “Shock & Kill”, this “Block & Lock” approach aims to silence HIV and prevent the emergence of virus when ART is stopped.

PI: Joshua Schiffer, MD
Fred Hutchinson Cancer Research Center, Seattle, WA
$200,000 (#109614)
Anti-proliferative therapy for eradication of the HIV reservoir: Antiretroviral therapy (ART) controls viral load because the virus is prevented from infecting new cells. However, the reservoir persists even under ART through mechanisms that are still being uncovered. One possibility is that normal cell division of latent HIV infected cells maintains the reservoir even in the absence of viral replication. Dr. Joshua Schiffer aims to determine if CellCept, a drug that reduces cell replication – normally used to prevent organ transplant rejection - can also eliminate the persistence of the reservoir. His clinical trial will span 2 years, after which participants will discontinue their ART and determine whether the curative intervention worked.

ARCHE Gene Therapy Grants

July 2017

Hildegard Büning, Ph.D. – principal investigator
Hannover Medical School, Hannover, Germany
$386,578 (109570)
Vector-mediated in vivo targeting of HIV reservoir cells or provirus elimination: To maximize safety of gene therapy, methods to specifically target reservoir cells are required. The HIV reservoir consists mainly of CD4+ T cells, with certain subsets more commonly harboring latent HIV. Dr. Büning plans to design an adeno-associated viral vector that specifically targets one of these main subsets, the central memory T cells. The vector will be designed to carry a gene editing tool called Brec1, previously shown to suppress HIV. One reported advantage of Brec1 over other gene editing tools is the apparent lack of off-target effects. 

Keith Jerome, M.D., Ph.D. – principal investigator
University of Washington, Seattle, WA
$399,955 (109575)
Subcutaneous administration of DARPin-modified adeno-associated virus vectors for selective targeting of CD4+ T cells: Curing a diffuse disease such as HIV, as opposed to a localized tissue-specific disease, requires a way to target the gene therapy to the target cells of interest, which in HIV are dispersed throughout the body. Dr. Jerome plans to use adeno-associated viral virus vectors engineered to utilize small, antibody-like  proteins to target the vectors and their gene-editing cargo directly to CD4+ T cells, which comprise the majority of the HIV reservoir. He will also experiment with ways of infusing the vectors such that they preferentially reach the lymph nodes, where most reservoir cells are found.

Hans-Peter Kiem, M.D., F.A.C.P. – principal investigator
Fred Hutchinson Cancer Research Center, Seattle, WA
$200,000 (109608)
Engineering blood cells to produce broadly neutralizing anti-HIV antibodies: Antibodies have been the focus of increasing optimism in the HIV cure research field due to their ability to not only neutralize virus particles, but also to target and help kill infected cells. Dr. Kiem plans to genetically modify immune system progenitor cells to serve as a constant source of antibodies. By engineering cells that will differentiate into a variety of types of immune cells, Dr. Kiem hopes that the progeny cells will migrate to various parts of the body, including lymph nodes and brain known to be important reservoirs of HIV.

Scott Kitchen, Ph.D. – principal investigator
University of California, Los Angeles, Los Angeles, CA
$400,000 (109577)
Optimized efficacy and persistence of engineered HIV-specific cellular immunity: Chimeric antigen receptor (CAR) cells have shown remarkable promise in their ability to clear some cancers in patients, and additionally have shown potential in HIV cure. Dr. Kitchen plans to improve the ability of CAR cells to kill HIV-infected cells by increasing their ability to detect the appropriate target cells and prolonging their survival. He also plans to engineer improvements to minimize the loss of CAR cells to attack by the immune system, and to design a mechanism to “switch off” CAR cells should they become unsafe or are no longer needed.

Yasuhiro Takeuchi, Ph.D. – principal investigator
University College London, London, United Kingdom
$360,034 (109584)
LentiStim: Mass production of lentiviral vectors for in vivo gene delivery: Curing HIV by gene therapy may require long-term persistence of the gene editing tools delivered by lentiviral vectors, which are closely related to HIV. Because the reservoir that harbors persistent HIV consists almost entirely of resting cells, such vectors cannot gain entry into the cells to deliver their cargo. Dr. Takeuchi plans to modify lentiviral vectors with a cocktail of stimulatory molecules that induce an optimal level of activation in the target cell, thus allowing entry of the vector. The effectiveness of lentiviral vectors is also plagued by immune responses raised against the vector, so the team will produce vectors that are resistant to destruction by the immune system.

Drew Weissman, M.D., Ph.D. – principal investigator
University of Pennsylvania, Philadelphia, PA
$400,000 (109587)
Targeting of nucleic acid therapeutics to cure HIV: Gene therapy approaches to cure HIV include efforts to cut the virus out of the human DNA, or to imbue the human host cells with characteristics that protect them from infection. Dr. Weissman plans to employ nucleic acid therapeutics as the tools to edit DNA to achieve either or both of these goals. One advantage of nucleic acid therapeutics is the ability to administer them repeatedly without raising an immune response that would destroy them. He plans to optimize their delivery to the appropriate cells by packaging them inside lipid nanoparticles that can be engineered with surface particles that guide them to specific targets.

Richard Wyatt, Ph.D. – principal investigator
The Scripps Research Institute, La Jolla, CA
$199,362 (109618)
Vector-mediated in vivo targeting of HIV reservoir cells or provirus elimination: Chimeric antigen receptor (CAR) cells have shown remarkable promise in their ability to clear some cancers in patients, and additionally have shown potential in HIV cure. One advantage is their ability to overcome a cancer or virus-infected cell’s ability to hide from the immune system. Dr. Wyatt plans to generate CAR T cells with the ability to kill HIV infected cells just as they begin to produce virus. Additionally, the CAR T cells will be engineered to produce antibodies that can neutralize any virus that is produced.

Shocking Latent HIV, Enhancing Immune Defense with a Single Drug

Last month we highlighted the work of scientists from the amfAR Institute for HIV Cure Research at the University of California, San Francisco, and their identification of a new pathway to induce HIV out of its latent state. Such activation renders the virus vulnerable to attack by the immune system. Unfortunately, many of the drugs currently being studied as such latency reversing agents work much better in the test tube than in patients.

Dr. Ole Søgaard

Writing in the June issue of the journal Clinical Infectious Diseases, amfAR-funded scientist Dr. Ole Søgaard of Aarhus University in Denmark, with colleagues from there and the University of Copenhagen, joining an international team from Barcelona, Berlin, Belgium, Boston, San Francisco, and Philadelphia, report on an experimental drug with the capacity not only to activate latent HIV, but also to enhance the patient’s innate immune defenses against the activated virus.

Lefitolimod, also known as MGN1703, activates a protein known as TLR9, found on the surface of many types of immune cells. It belongs to a class of agents known as “immune surveillance reactivators,” which induce production of immune hormones, such as interferon-alpha, and enhance the function of dendritic cells, B cells, and natural killer cells. All of these cell types form part of our innate defense against HIV. Lefitolimod is currently in advanced stages of testing in colon cancer patients.

Based on promising studies in the test tube with cells from HIV-infected patients, Søgaard and associates sought to test the drug’s effects in patients themselves.

Fifteen adults taking effective antiretroviral therapy (ART) for at least one year were enrolled in the study. Lefitolimod was injected under the skin twice a week for four weeks. In 40% of the participants, HIV levels dramatically increased, from undetectable (less than 20 copies) to over 1500 copies, consistent with the role of a latency reversing agent. In addition, the researchers observed an enhancement of all immune responses evaluated.

The authors noted that the use of another drug to enhance TLR7, a related immune surveillance reactivator, in monkeys infected with the simian form of HIV also showed promising results, but only when combined with a therapeutic vaccine.

They concluded that their research is “the first clinical trial using a single drug in HIV-1-infected individuals on ART with the aim of both enhancing innate immunity and activating the HIV-1 reservoir.”

Further studies are underway in this promising area of cure research.

Dr. Laurence is amfAR’s senior scientific consultant.

Gene-Editing Tool Reduces HIV in Infected Mice

Dr. Marcella Flores, associate director of research at amfAR

Researchers at Temple University and the University of Pittsburgh have been able to cut a fraction of HIV out of infected mice using CRISPR gene-editing technology, according to a new study in Molecular Therapy. The study builds upon previous findings by the research team, including one where CRISPR was used to cut HIV out of transgenic mice (genetically modified mice with HIV DNA inserted into their genomes—as opposed to having been infected with HIV).

In this study, researchers reduced HIV RNA (a measure of HIV) in transgenic mice by 60−95%. They were able to achieve a 96% reduction when they used the method in mice with EcoHIV, a mouse equivalent of HIV, during acute infection.

Employing a more widely used humanized BLT (bone marrow, liver, and thymus) mouse model, the researchers found that CRISPR was able to cut a fraction of HIV out of latently infected cells in some organs.

“It’s a good step forward,” said Dr. Marcella Flores, amfAR’s associate director of research. “It would be important to repeat the studies in monkeys and ensure that CRISPR is able to excise HIV from reservoir cells.”

Read more about the study here: http://bit.ly/gene-editing-tool

Using Mice to Detect 'Undetectable' HIV

A major part of amfAR’s “Countdown to a Cure for AIDS” initiative, which is aimed at developing the scientific foundations for a cure by 2020, is to determine the best method to detect and measure latently infected cells from individuals on antiretroviral therapy (ART).

Dr. Ramesh Akkina

This is critical to assessing the outcome of a cure intervention. Writing in the April issue of the journal Virology, amfAR-funded scientist Dr. Ramesh Akkina and colleagues at Colorado State University, along with researchers from the amfAR Institute for HIV Cure Research and Harvard University, reported a very novel approach.

The current “gold standard” for detecting persistent HIV is a test-tube technique known as qVOA (quantitative viral outgrowth assay). It is cumbersome and involves chemicals and antibodies in an attempt to activate virus in latently infected cells. One of its greatest drawbacks, however, is its inability to detect every virus that is capable of growing out of infected cells, estimated at approximately 60 per million cells. Akkina and colleagues sought a living alternative, using mice with human immune systems.

To “humanize” the mice and thus enable HIV to grow in these animals, the researchers used genetically immune-deficient mice transplanted with human stem cells or with bone marrow, liver, and thymus gland cells. They injected these animals with varying numbers of CD4+ T cells—from 100,000 to 20 million cells per mouse—obtained from 11 HIV-positive donors, all on ART. Five of these donors had undetectable viral loads by the standard qVOA.

The injected mice were followed for eight weeks. At weekly intervals blood was obtained in an attempt to detect, by a very sensitive molecular test known as RT-PCR, virus that wasn’t detectable using qVOA. Of the five qVOA-negative samples, four proved positive in the mice. The one sample that failed to produce virus was said to be of “poor quality”—donor samples had been frozen and don’t always thaw out well.

The authors concluded that the higher sensitivity of their humanized mouse models over qVOA and other types of mice used in similar experiments may ultimately lead to avoiding ART interruption as the only means to definitively assess the effectiveness of a potential HIV cure.

Let the mice do the work.

Dr. Laurence is amfAR’s senior scientific consultant.

Lab Mice Photo By Maggie Bartlett, NHGRI. - http://www.genome.gov/pressDisplay.cfm?photoID=5006, Public Domain, https://commons.wikimedia.org/w/index.php?curid=19805359