TAG HIV Basic Science, Vaccines, and Cure Project Blog

TAG’s HIV Cure-Related Clinical Research Listing: Background on the April 2024 Update

The April 2024 update to TAG’s listing features eight changes.

New Additions

Three new studies were added this month. All are protocols being initiated by the U.S. government-funded ACTG Network (formerly known as the AIDS Clinical Trials Group, recently revised to Advancing Clinical Therapeutics Globally).

The Antiretrovirals Combined With Antibodies for HIV-1 Cure In Africa (ACACIA) trial will evaluate a combination of two long-acting broadly neutralizing antibodies (bNAbs), 3BNC117-LS and 10-1074-LS, with infusions given at the time antiretroviral therapy (ART) is initiated. After 24 weeks, eligible participants will have the option to undergo an analytical treatment interruption (ATI) to assess capacity to control HIV viral load in the absence of ART. The study aims to build on evidence that giving bNAbs when ART is first started can accelerate depletion of the HIV reservoir.

According to the listing, the study is pending and not yet open for enrollment. No location information is provided but the ACTG website indicates there are sites in Botswana, Malawi, and South Africa. The trial will enroll 135 participants, making it one of the largest cure-related protocols with an ATI (and the largest on the African continent), second only to an ongoing international study sponsored by the pharmaceutical company AbbVie which plans to recruit 140 people.

The ACTG has also launched a study of a “triple immune regimen” that consists of therapeutic vaccines, bNAbs, and vesatolimod (an immune-modulating toll-like receptor 7 agonist) in people who initiated ART within 28 days of being diagnosed with acute (recently acquired) HIV. The trial similarly involves an ATI to evaluate whether the interventions can enhance immune system control of HIV viral load. Enrollment is open and the intent is to recruit 45 participants at sites in the U.S. and Brazil.

The final addition is an ACTG observational protocol for any participants in these or other network (or related) trials who experience sustained (at least 24 weeks) low viral load levels after receiving a cure-related intervention and undergoing an ATI. The exact definition of low viral load will be based on the criteria used by the studies they were participating in, but the level cannot have risen to over 1,000 copies/ml for four or more consecutive weeks and CD4 T cell counts must be greater than 350.  

All three of these studies had been entered into the clinicaltrials.gov registry over the past few months, but a glitch with the search function of the recently overhauled website meant that we failed to identify them in searches of the database for “HIV” because the condition they’re listed under is “HIV-1-infection” and they fail to appear in results. The search function on the old “classic” version of clinicaltrials.gov doesn’t make the same error, which is something to be aware of for anyone who uses the registry to track HIV-related clinical research.

Updates to Enrollment Status

The RHIVIERA-02 study in France is now open for enrollment. The investigators are recruiting people with recently acquired HIV and testing whether giving the long-acting bNAbs 3BNC117-LS and 10-1074-LS at the time of ART initiation can lead to control of viral load during a subsequent ATI (after at least 52 weeks on treatment).

A clinical trial of baricitinib that was temporarily suspended is now open for enrollment at two sites in Atlanta. Baricitinib belongs to a class of drugs called Janus kinase inhibitors and is FDA-approved to treat severe rheumatoid arthritis and several other conditions. The HIV study is sponsored by William Tyor at Emory University, based on findings from laboratory experiments in humanized mice indicating that baricitinib has the potential to cross the blood-brain barrier and reduce viral persistence in the central nervous system. The trial will investigate if similar effects can be obtained in people with HIV, using blood samples, neurocognitive testing, magnetic resonance imaging (MRIs), and lumbar punctures.

Completed Studies

Occasionally research studies only get added to registries after completion, presumably due to an oversight. This is the case for AVIR, an observational study measuring the HIV reservoir in a large cohort of adolescents in Cameroon living with locally prevalent HIV clades. Results were published in the Journal of Virus Eradication on March 30, reporting that earlier ART initiation (within the first year of life) and longer duration of treatment (>9 years) were associated with smaller reservoirs as measured by HIV DNA. The researchers also identified modest correlations between levels of HIV DNA and HIV RNA, with higher viral loads linked to larger reservoirs.

New Links to Study Results

A link was added to another abstract from last month’s Conference on Retroviruses and Opportunistic Infections (CROI): Leah Carrere from the Ragon Institute presented a poster on a participant from the eCLEAR trial who has now maintained post-treatment control of HIV viral load for over five years after interrupting ART (the trial is completed and the primary results were published in Nature Medicine in 2022). Carrere also gave a brief talk during a poster discussion session at the meeting, which is now available for viewing via webcast (all the CROI materials were made publicly available on April 8th).

The study found evidence that cells containing intact, viable copies of HIV potentially capable of causing viral load rebound had been depleted by the individual’s immune responses, leaving behind a viral reservoir constricted in its ability to emerge and replicate. The constriction is a consequence of the HIV genetic code being integrated into areas of the cell’s DNA genome that are largely inactive, preventing the virus from hijacking the cell’s genetic machinery to make new copies of itself. A similar phenomenon has been reported in the two cases of HIV elite controllers who appear to have cleared all viable HIV from their bodies over time (Loreen Willenberg and the Esperanza Patient), and in some studies of people on long-term ART as well as in a small trial of panobinostat and alpha interferon (see also last month’s blog post and Tim Murphy's interview with Marie Armani-Tourret, Ph.D. for TheBody.com).

Results from a study of very early ART initiation being conducted at the University of California San Francisco that were presented at the IAS 2023 conference are now available as a preprint from medRxiv. Preprint means that the report has not yet been reviewed by scientific peers (a full publication in a peer-reviewed journal typically follows). The study documents a faster decline in levels of both intact and defective HIV after very early ART compared to studies of people who started treatment later.

Davey Smith and colleagues from the University of California San Diego have published their findings from a clinical trial that assessed the capacity of influenza and pneumococcal vaccines to essentially act as latency-reversing agents by stimulating the HIV reservoir to produce viral RNA. The analysis revealed that neither vaccine had significant effects on HIV RNA levels.

Lastly, 157 participants in the observational HEATHER (HIV Reservoir targeting with Early Antiretroviral Therapy) cohort study in the United Kingdom contributed samples to an analysis of the prevalence of resistance to the bNAb 10-1074, which is under investigation in multiple cure-related trials (the work was published in the journal Frontiers in Immunology).

The researchers found that HIV samples from around a third of the participants displayed genetic mutations associated with resistance to 10-1074, with evidence that the prevalence is increasing over time. Echoing previous reports, the study also documented that HIV from non-B clades (specifically CRF01-AE) displayed higher levels of resistance to 10-1074. The authors note that predicting resistance to bNAbs based on genetic analyses can be complex, and emphasize that improved tools are needed to screen potential recipients for baseline resistance to bNAbs.

TAG’s HIV Cure-Related Clinical Research Listing: Background on the March 2024 Update

The March 2024 revision to TAG’s listing includes 26 updates. The annual Conference on Retroviruses and Opportunistic Infections (CROI) took place in Denver from March 3-6, and the addition of links to results from HIV cure-related studies presented at the meeting typically makes this the busiest month for changes — hence the delay to this blog post.

New Additions

Three new studies were added this month.

Gilead Sciences is one of the few large pharmaceutical companies pursuing an HIV cure research program. As part of this effort, a phase I trial has been initiated of GS-8588, an immune-based therapeutic candidate described as a bispecific T cell engager.

The approach derives at least in part from research conducted with public funding at the National Cancer Institute by Dimiter Dimitrov and Weizao Chen. The scientists developed and patented a protein with two components (bispecific): mD1.22, an element from the human CD4 protein, and m36.4, from a human antibody, each specific for a different vulnerable target on HIV’s outer gp120 envelope protein. The Gilead construct includes a CD3 molecule to engage T cells to kill cells expressing the HIV gp120 protein; all the ingredients included in GS-8588 will be described in a presentation by Nathan D. Thomsen from Gilead at a conference in May of this year.

GS-8588 is an example of how research supported by public funding from the National Institutes of Health (NIH) can be licensed to a private company for potential profit. When the NIH requested public comment on their plan to license the fusion protein to Gilead, Jamie Love’s organization Knowledge Ecology International filed comments highlighting concerns about cost and the lack of any requirements for access and availability if the approach should prove successful:

“The NIH should include terms in the license that protect affordable, equitable access to patients in the US and around the world. Gilead has a track record of pricing its treatments - including HIV products - aggressively, and in the past, the high prices have been a barrier to the deployment of PrEP to prevent HIV infections.”

The response from NIH doesn’t disclose whether any such terms were included.

Gilead hasn’t entered the GS-8588 trial into the clinicaltrials.gov registry (at least so far), taking advantage of the lack of a requirement to register phase I trials. This has been a consistent problem with Gilead’s HIV cure research program, and it runs counter to their public commitments to community engagement in HIV research — it’s not possible for people to engage with a clinical trial if they’re not aware of it. Limited information is available online from individual study sites, such as the entry in the UPenn Medicine website. Gilead also states that GS-8588 is in a phase I trial on their website pipeline page, without providing any additional detail.

Casper Rokx and colleagues at the Erasmus Medical Center in the Netherlands are working to translate findings from laboratory analyses of candidate HIV latency-reversing agents into clinical interventions. Their newest trial (not yet recruiting) plans to investigate the activity of an approved antiepileptic drug, topiramate, in people with HIV on antiretroviral therapy (ART).

The rationale derives from laboratory studies showing that a particular cellular gene — glutamate ionotropic receptor kainate type subunit 5 (GRIK5 for short) — is involved in the maintenance of HIV latency. Topiramate is an inhibitor of GRIK5 and was found to reverse HIV latency in cell line models and in CD4 T cells isolated from people on ART, without inducing immune activation or causing significant toxicity.

The clinical trial will administer a single topiramate dose of 400mg to assess HIV latency-reversing activity, toxicity, and any differences in response related to sex assigned at birth.

The third addition is sponsored by the French National Agency for Research on AIDS and Viral Hepatitis (ANRS) and involves participants in a cohort of children with HIV treated early with ART in the ANRS Pediacam III cohort in Cameroon. The goal of the study is to better understand the factors that contribute to maintenance of HIV-negative results on antibody tests in a subset of cohort members.

Updates to Enrollment Status

A clinical trial in Spain investigating the tyrosine kinase inhibitor dasatinib in people with HIV is now open for enrollment. The protocol aims to recruit people with recent HIV acquisition (past 3-12 months) and will administer dasatinib (70mg a day) alone for four weeks before ART is initiated. Dasatinib will then be continued as an adjunct to ART for another 12 weeks. Study endpoints include the safety and tolerability of dasatinib both alone and in combination with ART, effects on HIV viral load prior to ART, and measurements of the HIV reservoir.

The impetus for the study (and another recently opened trial in Spain recruiting people on ART for >3 years) comes from evidence that the use of dasatinib to treat cancers in people with HIV is linked to smaller reservoir size and a diminished capacity to reactivate viable HIV from latently infected cells.

A phase I trial in China of ICVAX, a therapeutic vaccine candidate, is now closed to new enrollment. ICVAX takes a novel approach by targeting the PD-1 pathway to try to improve immune responses against the HIV Gag proteins included in the vaccine construct. Preliminary information from the trial was presented at an IAS 2023 pre-conference by Zhiwei Chen (see blog post from August 2023).

Completed Studies

An interesting-looking trial that planned to investigate an off-the-shelf natural kill cell product called FT538 in people with HIV on ART has unfortunately been withdrawn (and deleted from TAG’s listing). The study record provides no information except stating: “Withdrawn, Abandoned.” Fate Therapeutics, the company that produced FT538, no longer lists it in their pipeline suggesting development has been discontinued.

New Links to Study Results

The majority of newly added links to study results derive from CROI 2024. Links are included to the conference abstracts, with PDFs of posters already available but webcast links for oral presentations due to be added to the respective abstract pages and made publicly accessible on April 8, 2024.

The multinational IMPAACT P1115 study is evaluating whether the extended period of remission from detectable HIV viral load that was documented in the Mississippi baby case may be reproducible in other infants with HIV treated very early after birth. At CROI 2024, Dr. Deborah Persaud presented the first study results after analytical treatment interruptions (ATIs), noting that six infants met pre-specified criteria for stopping ART, including absence of detectable HIV DNA. The average age at time of interruption was 5.5 years. Viral load returned quickly in two of the children. In another participant, there was a delay of 80 weeks before viral load rebounded necessitating the reintroduction of ART. The reappearance of viral load was associated with symptoms of acute HIV infection in two of these cases. Three study participants currently remain off ART without viral load rebound after 48, 52 and 64 weeks of ongoing follow up, respectively.

Persaud noted that the study demonstrates that extended remission from detectable viral load is possible in very early-treated infants, but better biomarkers are needed to identify the ideal candidates. A second version of the IMPAACT P1115 protocol is investigating whether the inclusion of an integrase inhibitor and a broadly neutralizing antibody (bNAb) in treatment regimens can improve outcomes. See Liz Highleyman’s report for Aidsmap for detailed coverage. A second IMPAACT P1115 abstract presented as a poster reported results from a detailed analysis of the HIV reservoir among infants in the study, showing that around half of the HIV DNA detected at birth represented intact virus genomes, with levels subsequently declining after ART initiation.

Marie Armani-Tourret from the Ragon Institute described results from a completed clinical trial of the HDAC inhibitor panobinostat combined with interferon-alpha2a in people on ART. The results were also published in the journal Cell shortly before CROI 2024. The researchers found evidence that the interventions altered the makeup of the HIV reservoir, with a trend toward a reduction in the proportion of intact HIV (viable virus that can cause viral load rebound) and an apparent depletion of cells containing virus integrated in places in the cell’s genetic code known to be susceptible to the latency-reversing activity of panobinostat. The authors conclude “these results provide proof-of-principle that the viral reservoir is vulnerable to ‘shock and kill’ interventions.”

Two oral presentations reported on different approaches to combining three bNAbs (see also Gus Cairns’s coverage for Aidsmap). Boris Juelg conducted a study of PGT121, PGDM1400, and VRC07-523LS given as monthly infusions, with ART interrupted after the first infusion. At CROI, Juelg reported that a majority of participants (10 of 12) maintained viral load suppression during bNAb dosing, and several (5 of 12) displayed extended post-treatment control after antibody levels waned. Participants weren’t pre-screened for evidence of baseline resistance to the bNAbs, and the two individuals with early viral load rebound were found to have HIV mutations associated with reduced susceptibility to PGT121 and PGDM1400. A poster from the same study identified inflammatory markers that appeared to increase prior to viral load rebound, suggesting they could have a role as predictors of loss of control of HIV replication.

Athe Tsibris debuted results from an ACTG study of SAR441236, a construct originally developed by Sanofi Pasteur that combines three bNAbs (VRC01, PGDM1400 and 10E8v4) into a single antibody construct. The antibody behaved similarly to other long-acting bNAbs in terms of the levels achieved in the body after administration, but the viral load effect in people not on ART was very weak for reasons that are unclear (0.38 log reduction at the highest dose, compared to declines averaging around 1.5 logs observed previously with single bNAbs). The candidate has been acquired from Sanofi Pasteur by a company called ModeX Therapeutics who issued a modest press release noting only that the safety and pharmacokinetics support further development of multispecific antibody approaches.

Several abstracts presented additional information from the BEAT-2 trial conducted by the BEAT-HIV Martin Delaney Collaboratory. Katherine Bar described evidence that both the bNAbs administered during the trial and the participants' own neutralizing antibody responses against HIV (called autologous neutralizing antibody responses) exerted activity against the virus that led to the selection of mutations associated with resistance. The bNAb infusions were also linked to improvements in the potency of participant autologous neutralizing antibody responses. In two participants who experienced the longest delay in viral load rebound after an ART interruption, autologous neutralizing antibody responses against HIV were already detectable when they first entered the study. The findings imply that autologous neutralizing antibody responses can contribute to post-treatment control of viral load.

A separate poster abstract from BEAT-2 reported an unexpected decrease in antibody-mediated cellular cytotoxicity (ADCC) associated with the interventions. Two additional posters provided information on the development of an experimental home viral load testing device evaluated as part of the protocol, and presented results suggesting that the approach may have utility for home monitoring of viral load rebound during ATIs. The device works by allowing the collection of capillary blood samples at home; the blood dries and is then sent for HIV viral load analysis via mail.

Tim Henrich from the University of California San Francisco (UCSF) gave an update from an ongoing imaging study assessing immune activation in people with HIV using positron emission tomography (PET) scanning. Henrich found that T cell activation was generally elevated in the participants with HIV compared to HIV-negative controls, including in people on ART. An exception was inguinal (groin) lymph nodes, where T cell activation was lower in people with HIV compared to the controls, possibly suggesting a decline in the capacity to activate T cells in these locations linked to the persistent presence of the virus. As an aside, Henrich noted that background levels of T cell activation detectable by this method have increased among all study participants in the post-COVID era, as evinced in a different study investigating long COVID (results are available as a preprint). A poster from Frank Maldarelli’s research group at the National Cancer Institute offered an update on the use of the same technique in a currently open study involving an ATI.

The pharmaceutical company AbbVie provided updates on their HIV cure research program in the form of an oral presentation on biomarkers associated with responses to their PD-1 inhibitor budigalimab and a poster describing the potential ability of a partner antibody targeting the α4β7 integrin (ABBV-382) to both directly inhibit HIV and enhance the presentation of viral antigens to T cells. Results from their phase I budigalimab program were previously covered on the blog. A large multinational phase II trial is now underway which plans to enroll 140 participants and explore the combination of budigalimab and ABBV-382.

Many other CROI 2024 posters featured results from studies in TAG’s listing.

The PENTA Foundation is sponsoring an ongoing trial in adolescents who acquired HIV perinatally, testing two therapeutic HIV vaccine candidates and the Cervarix human papilloma virus (HPV) vaccine (the latter given as an adjuvant because it contains a toll-like receptor 4 agonist). No efficacy data is available yet, but a poster presented information showing that the interventions have demonstrated safety.

Three posters reported analyses of participant samples from the large 2000HIV cohort study in the Netherlands. An investigation into genetic associations with natural control of HIV viral load found evidence to suggest that certain gene variants contribute to an increased capacity to restrict viral replication by modulating the function of natural killer (NK) cells. A separate study conducted the largest assessment of the intact HIV reservoir in different populations of people living with HIV (total = 863), finding that participants with various degrees of natural control of viral load have lower levels of intact HIV DNA compared to those with a more typical pattern of disease progression (designated “normal progressors”). People with suboptimal CD4 T cell recovery despite ART displayed significantly higher levels of intact HIV DNA compared to the normal progressors. Additionally, participants with HIV variants that use the CXCR4 co-receptor to enter cells had higher levels of intact HIV DNA than counterparts with viruses targeting the CCR5 co-receptor. In a novel companion study that also involves HIV-negative family members of participants with HIV, a particular profile of increased responsiveness among innate immune cells called monocytes (referred to as trained immunity) was associated with elite controller status.

Two abstracts covered analyses from a small trial of multiple interventions (therapeutic HIV vaccines, bNAbs and a TLR9 agonist) being led by Michael Peluso at UCSF. Results were presented as a poster at CROI last year indicating viral load rebound after ATI was reduced compared to the typical pattern, with 5 out of the 10 participants controlling viral load to <1,000 copies/ml (there’s no placebo control group in the study). One participant maintained undetectable viral load for 18 months of follow up, which is potentially encouraging albeit a challenging situation for the individual, Luis Canales, as he described in a recent article for Positively Aware. The posters presented at CROI 2024 reported an association between control of viral load and the ability of CD8 T cells to proliferate (copy themselves) in response to the rise in HIV levels after ATI, as well as assessing the impact of bNAb levels and concluding that they likely didn’t directly contribute to the apparent reductions in set point viral load but were linked to the timing of rebound (with higher bNAb levels linked to a longer delay).

Another study at UCSF led by Sulggi Lee is investigating the effects of rapid ART initiation after HIV acquisition on the viral reservoir. Initial results presented at IAS 2023 showed that participants who started ART earliest experienced the most rapid declines of both intact and defective HIV DNA. One poster at CROI 2024 outlined an association between higher levels of the cytokines IL-10 and type I interferons and more rapid declines in intact HIV. A second poster featured an analysis by Steven Yukl and colleagues which found that ART reduced both the proportion of cells in which the HIV life cycle was being completed, and levels of intact HIV RNA (which is transcribed from intact HIV DNA during the viral life cycle).

The SCOPE cohort at UCSF is recruiting participants for an ATI study that restarts ART as soon as viral load is confirmed to have increased to detectable levels (or after around three weeks if viral load remains undetectable). Two poster abstracts at CROI reported initial results from current participants. An analysis by Mauro Garcia and colleagues found an association between time to viral load rebound and the levels of HIV variants in the reservoir that were susceptible to autologous neutralizing antibodies: participants with higher levels of HIV in their reservoir that could be inhibited by their autologous neutralizing antibody responses experienced a longer time to rebound. The results echo those of Katie Bar and add to the evidence that neutralizing antibody responses can play an important role in post-treatment control of HIV. The second poster presentation from Natalia de la Force notes that an increase in levels inflammatory monocytes preceded the rise of viral load to detectable levels.

An ACTG trial of the anti-CMV drug letermovir was stopped early because changes in the levels of certain inflammatory markers didn’t meet criteria prespecified in the protocol as necessary for recruiting additional participants. In a late-breaker poster at CROI, Sara Gianella Weibel described an analysis involving 40 participants after eight weeks. Unexpectedly, there was an increase in one marker of inflammation, soluble tumor necrosis factor receptor 2 (sTNFR2), likely connected to a reduction in levels of an immune-suppressive protein generated by CMV. However, other markers associated with inflammation and cardiovascular disease risk declined, suggesting the approach may deserve further evaluation.

The last of the CROI abstracts so far identified as related to trials in the TAG listing came from the RIVER trial in the UK, which tested therapeutic vaccination in people starting ART early after HIV acquisition. In a subset of 10 participants whose samples were studied in detail, early ART initiation was linked to a shift in the composition of the HIV reservoir suggestive of immune-mediated clearance of cells containing HIV capable of making viral proteins either intermittently or persistently (thereby making the infected cell visible to the immune system). The evidence derived from an increase in the proportion of cells with HIV integrated into locations in the cellular genetic code known to restrict the capacity of the virus to emerge and make new proteins, keeping it hidden. However, these effects on the HIV reservoir were associated with markers of innate immunity and not with receipt of the therapeutic vaccine.

Links to newly published results were added for four studies in the listing:

In the journal Open Forum Infectious Diseases, Cynthia Gay and colleagues reported complete findings from an ACTG trial of the PD-1 inhibitor cemiplimab which was stopped early due to two serious adverse events (already described at the 2020 Pre-CROI Community HIV Cure Research Workshop and in a paper in JAIDS). The new publication notes there was evidence of an increase in HIV-specific T cell responses in one of four recipients studied. Multiple other studies of PD-1 inhibitors in people with HIV (with or without cancer) remain ongoing.

An observational study in people on ART in Rakai, Uganda found evidence of a temporary increase in the size of the replication-competent HIV reservoir after switching to an integrase inhibitor-based ART regimen (primarily from previous NNRTI-based ART). The researchers note there might be possible confounding variables and that it will be important to assess whether a similar phenomenon occurs in other cohorts. The results were published in the open access journal EBioMedicine.

An ongoing observational study in France titled APRIL (Analysis of the Persistence, Reservoir and HIV Latency) presented an analysis of HIV target cells in people with late stage disease in the journal Pathogens & Immunity. The authors report that productively infected cells in people with AIDS were highly differentiated and exhausted — indicating they’d been exposed to multiple rounds of stimulation leading to dysfunction.

Lastly, the researchers conducting the Zurich Primary HIV Infection Study published a description of their cohort in the journal Microorganisms.

TAG’s HIV Cure-Related Clinical Research Listing: Background on the September 2023 Update

There are twelve updates to the listing this month: four new interventional trials and one observational study have been added (all yet to start recruiting), a planned observational study was withdrawn, a trial of immunomodulators has begun recruiting in China, one trial has shifted to the completed studies table, and links to presentations/publications describing results were added for four studies in the listing.

The ACTG is sponsoring a new placebo-controlled study of a single infusion of each of two long-acting broadly neutralizing antibodies (bNAbs) followed by an analytical treatment interruption (ATI) in people on antiretroviral therapy (ART) at sites in Botswana, Malawi, and South Africa. The bNAbs are 3BNC117-LS-J and 10-1074-LS-J. The plan is to enroll a total of 48 participants, who’ll be randomized to receive the bNAb infusions or placebo versions and start an ATI two days later. The eligibility criteria require that participants have been on a suppressive ART regimen for at least 96 weeks (with some allowance for a short interruption during that period). The researchers will evaluate the capacity of the bNAbs to delay viral load rebound above a threshold of 200 copies/ml (suggesting that an increase of viral load above this level will trigger the restarting of ART). The ACTG is currently in the process of revising their former name AIDS Clinical Trials Group to just the acronym, which has been altered to stand for: Advancing Clinical Therapeutics Globally for HIV/AIDS and Other Infections (to reflect the broadening of their mission).

At the Research Institute of the McGill University Health Centre in Canada, Jean-Pierre Routy is initiating a trial that will investigate the safety and effects of fecal microbiota transplantation (FMT) on gut integrity, inflammatory biomarkers, and HIV reservoir measures in people on ART. As outlined in a recent meta-analysis of 10 prior studies, FMT has shown some potential efficacy in restoring healthy gut bacteria and reducing the rate of gastrointestinal infections in PWHIV, with a safety profile similar to that observed in HIV-negative people. Routy’s study will enroll 20 participants with half randomized to receive FMT capsules and half receiving a placebo equivalent. The researchers are limiting the study to people with a CD4:CD8 ratio <1 in order to focus on a population most at risk for persistent inflammation.

The pharmaceutical company AbbVie recently entered the realm of HIV cure research without great fanfare and is now about to launch a combination trial assessing a combination of two antibody-based therapeutics that they’ve previously studied individually in PWHIV (results from those studies have not been publicly presented yet to our knowledge). Budigalimab is an anti-PD-1 antibody that belongs to the class of interventions called immune checkpoint inhibitors (several are licensed for the treatment of cancers), while ABBV-382 is an anti-α4β7 integrin antibody similar to vedolizumab (an antibody approved for ulcerative colitis and Crohn's disease). According to the study record, AbbVie plans to recruit 140 participants at approximately “90 sites worldwide.” The protocol involves an ATI and will evaluate the effect of the antibodies (alone or in combination) compared to placebo on time to viral load rebound greater than 1,000 copies/ml. Based on the company’s website pipeline page, it appears that the ultimate goal may be to combine the two antibodies into a single construct (codenamed ABBV-1882) that can target both PD-1 and the α4β7 integrin. The interventional trial that was completed this month is AbbVie’s phase Ib assessment of ABBV-382 alone — although results don’t appear to be available yet, it seems reasonable to assume that the data supported progressing to the larger combination study.

The last of the new interventional trials is sponsored by the HIV Vaccine Trials Network and aims to test an HIV vaccine construct in PWHIV on ART who will undergo an ATI. The vaccine is part of an effort to develop a “germline targeting” strategy that can eventually lead to the generation of bNAbs. The main goal of the study is to assess how HIV viral load rebound during ATI affects the B cell and antibody responses induced by the vaccine. The rationale is that further stimulation of vaccine-induced B cells by HIV may conceivably drive a process called maturation that can lead to the production of more effective antibody responses, and the researchers plan to study this very carefully. There are also a number of secondary outcome measures focused on the experience and perspectives of the study participants, because while this work may be able to contribute to cure research, the primary focus is on informing the development of an effective preventive HIV vaccine.

The lone new observational study is sponsored by the University Hospital, Ghent and intends to undertake a detailed characterization of the HIV reservoir in individuals who are naturally controlling viral load to low levels in the absence of ART. The observational study that was withdrawn this month was from the same sponsor; the clinicaltrials.gov record notes that it wasn’t able to open because a commercial partner decided not to proceed with the project.

A study of two potential immunomodulators, lenalidomide and adenosylmethionine (added to the listing in November 2022) is now open for enrollment at the First Affiliated Hospital of Zhejiang University School of Medicine in China.

The new links to publications and presentations include:

• Videos of talks at the IAS HIV Cure & Immunotherapy Forum related to the RIO trial and the ICVAX therapeutic vaccine study
• An IAS 2023 abstract reporting a new analysis involving participants in the completed ISALA ATI study in Belgium
• The published results of the completed TITAN trial that combined dual bNAbs with the toll-like receptor 9 agonist lefitolimod (these results were covered in TAG's 2023 Research Toward a Cure and Immune-Based Therapies Pipeline Report)

New Insights into Elite Control of HIV and a Possible Case of Virus Clearance

Several media outlets are reporting on a newly published study of elite controllers, a rare subset of people with HIV who suppress viral load to low or undetectable levels without treatment. A major impetus for the interest is a finding that one long-term elite controller, Loreen Willenberg, may have cleared all the intact HIV from her body. The study was published today in the journal Nature (paired with an open access commentary by Nicolas Chomont), and Apoorva Mandavilli covered the research in a story for the New York Times. Jon Cohen has authored an excellent explanatory article for Science. The study results offer potentially important clues about how HIV may be cured in some circumstances, but unfortunately do not directly help design interventions that might produce similar outcomes in the majority of people living with the virus (who are not elite controllers).

The crux of the new paper is that elite controllers appear to preferentially deplete the HIV-infected cells from their bodies that contain virus capable of replicating, likely due to potent anti-HIV immune responses (particularly HIV-specific CD8 and CD4 T cells). The HIV-infected cells that are left behind preferentially harbor viral DNA in regions of the cell’s genetic code that are inactive, essentially entombing the virus and preventing its reemergence. In some cases, the HIV DNA is not intact, which also prevents further replication. For Loreen Willenberg, analyses of huge numbers of cells from both the blood and gut could not find any intact HIV, leading to the suggestion that all virus capable of replicating (referred to as replication-competent HIV) has been eliminated over time.

In the New York Times article, scientist Steve Deeks notes that a somewhat similar phenomenon may occur in people with HIV on long term antiretroviral therapy (ART), raising the possibility that over a period of decades cells containing replication-competent virus might be eliminated. Deeks intends to investigate this scenario in people on very long-term ART. However, it’s important to note that the evidence is very thin—the most detailed paper indicating the phenomenon might be occurring involves only three individuals on ART. Furthermore, the Nature paper compares elite controllers with people on ART, finding that the entombment of HIV in cells is far more common in the former group than the latter. Given the significant uncertainty, people on long-term ART shouldn’t attempt to interrupt treatment outside of research studies.

Another way researchers are attempting to translate the knowledge gleaned from elite controllers is by testing approaches that may be able to enhance immune responses against HIV. Examples include therapeutic vaccines, broadly neutralizing antibodies, toll-like receptor agonists and gene therapies (see TAG’s Research Toward a Cure clinical trials listing and 2020 Pipeline Report). Success to date has been limited, and part of the challenge may be that elite controllers tend to possess particular genetic traits associated with superior HIV-specific immunity.

While the Nature paper was published today, the content was partially known to people who follow HIV research. Xu Yu described some of the data, including the case of Loreen Willenberg, at the IAS 2019 conference. Loreen was subsequently profiled in an article for Leapsmag by Bob Roehr. In a tour-de-force plenary talk on cure research at CROI 2020 earlier this year, Sharon Lewin highlighted the need to consider how much of the HIV reservoir that persists on ART is replication-competent and able to reemerge if treatment is interrupted. Lewin cited the work of the Nature paper’s lead author Chenyang Jiang, who also presented during the conference.

Halting Start for Kick & Kill, CROI Previews New Approaches on the Horizon

One of the most widely discussed and publicized ideas for targeting the HIV reservoir is “kick and kill” or “shock and kill.” The aim is to kick dormant, latent HIV into revealing itself so the cells that contain the virus are visible to the immune system; the kill aspect involves trying to enhance the immune response so it’s able to recognize and destroy these HIV-infected cells. The ultimate goal is to deplete the latent HIV reservoir that persists in people on antiretroviral therapy (ART).

The RIVER trial, launched in the UK in December 2015, represents the first large, randomized controlled evaluation of the approach. Preliminary results were first reported at the AIDS 2018 conference in Amsterdam, and have now been described in detail in a paper in Lancet HIV. While the interventions were unable to reduce the HIV reservoir, the negative outcome still holds important lessons for the cure research field. New candidates for both the kick and the kill are in the research pipeline.

RIVER recruited a total of 60 participants with primary HIV infection—all men—and randomized them to receive either a standard ART regimen plus the integrase inhibitor raltegravir or standard ART, raltegravir, a prime-boost therapeutic HIV vaccine combination and a short course of the HDAC inhibitor vorinostat (a latency-reversing agent reported to have some activity in prior trials). The vaccines consisted of chimpanzee adenovirus and modified Vaccinia Ankara strain virus vectors carrying HIV antigens designed to induce T cell immune responses focused on parts of the virus that mutate the least (conserved regions).

The results showed that after 16-18 weeks there were no differences between the two groups in any measures of HIV persistence, including HIV DNA and the quantitative virus outgrowth assay (QVOA). A laboratory test assessing the ability of CD8 T cells to kill HIV-infected cells indicated that therapeutic vaccination helped maintain this capacity: killing activity declined from baseline in the ART only arm of the study but was maintained in the intervention arm. Vorinostat increased histone acetylation after dosing (the mechanism by which it can trigger the activity of latent HIV), however sensitive tests for low-level HIV RNA did not reveal any concomitant increases suggestive of HIV latency reversal.

In discussing their findings, the authors posit a number of possible reasons why this particularly kick and kill combination did not prove effective. Fewer doses of vorinostat were used than in some prior trials, and the evidence of latency reversal that has been described (increases in HIV RNA associated with dosing) was obtained in people with chronic rather than primary HIV infection. Another possibility is that even if vorinostat did cause some latently infected cells to reveal themselves to the immune system by expressing HIV antigens, the HIV-specific CD8 T cells induced and/or maintained by therapeutic vaccination may not have been capable of recognizing these antigens. Presentation of the antigens to CD8 T cells could also be inhibited by the HIV Nef protein, which is known to have the capacity to interfere in this process.

The researchers also acknowledge the argument that analytical treatment interruptions (ATIs) may be a better test of the effects of interventions than laboratory measures of the HIV reservoir, but at the time RIVER was designed ATIs were not in favor due to safety concerns, and they still believe that an ATI wouldn’t be justified in this case. They conclude that:

“RIVER helps to set the standard for how future trials might be done because of the new insights gained with regard to trial design, the inclusion of community representation, the need for better interventions, the necessity for clarity regarding the most relevant measures of the reservoir, and probably the use of an analytical treatment interruption approach.”

An example of a next generation kick and kill study was presented last week at CROI by Ole Schmeltz Søgaard. Known as ROADMAP, the trial compared romidepsin (an HDAC inhibitor that appears to have greater latency-reversing activity than vorinostat) to romidepsin plus the broadly neutralizing antibody (bNAb) 3BNC117 in people with chronic HIV infection on long-term ART. The bNAb was included in hopes of both promoting killing of HIV-infected cells via antibody-dependent cellular cytotoxicity (ADCC) and enhancing HIV-specific T cell immunity (as recently reported in a study of 3BNC117 combined with another bNAb, 10-1074).

A total of 20 participants were enrolled (17 men and three women); 11 were randomized to receive 3BNC117 and romidepsin, nine to romidepsin. There were two cycles of romidepsin administration: at weeks 0, 1, 2 and weeks 8, 9, and 10. The 3BNC117 group received a single infusion of the bNAb two days prior to these cycles. After 24 weeks, participants underwent an ATI in order to evaluate time to viral load rebound (defined as two consecutive measures equal to or greater than 200 copies/mL). Two participants opted out of the ATI, while a third was excluded after stopping ART while receiving romidepsin.

Søgaard reported that, disappointingly, there was no significant difference in time to viral load rebound between the two arms of the study: it took an average of 28 days in the romidepsin group compared to 17.5 days in the 3BNC117 plus romidepsin group. The slight difference in favor of the romidepsin group wasn’t statistically significant and Søgaard noted it was driven by one outlying participant who didn’t experience rebound until 12 weeks into the ATI.

HIV DNA levels measured at the midpoint between the romidepsin cycles and immediately prior to the ATI showed no significant changes. HIV-specific CD8 T cell responses remained stable over the same period and weren’t enhanced by 3BNC117 administration or negatively affected by romidepsin.

As was the case in the RIVER trial, Søgaard concluded that this particular combination was ineffective and that superior strategies are needed.

At CROI, Sharon Lewin—a leading scientist in HIV cure research—delivered an impressive, comprehensive update on the field, providing reasons to hope that better results will be obtainable in the future.

One key development is that the scientific understanding of HIV latency has improved significantly in recent years. The picture is now far more nuanced compared to when the HIV reservoir was first identified in the late 1990s.

The first relatively new concept highlighted by Lewin is that not all latent HIV remains stably latent (inactive) in people on effective ART. The HIV DNA that’s integrated into the genomes of infected cells can be transcribed into HIV RNA (which in turn can make HIV proteins), either intermittently or possibly also continuously in some cases.

A number of factors can affect the transcription of HIV DNA into HIV RNA, including the location of the infected cell. Lymph nodes, the gastrointestinal tract and the female genital tract are sites where HIV RNA is most frequently detected. Time of day also has an influence because proteins involved in the circadian cycle can activate HIV transcription, leading to fluctuations in HIV RNA levels.

Lewin described this phenomenon as “reservoir activity” and it’s important to stress that it does not represent ongoing HIV replication—any new infectious HIV viruses that are produced would be blocked from infecting new cells by the presence of ART. Gaining an understanding of the processes involved in reservoir activity should help researchers develop better latency-reversing agents.

Another aspect of HIV latency that is now coming into view is the importance of where exactly the virus lands when it integrates into the genome of a cell. As a loose analogy, if you think of the genome as a factory for producing all the proteins a cell needs to go about its business, HIV DNA tends to land in machinery that gets switched on regularly, which gives the virus opportunities to hijack that machinery to make more HIV RNA (and potentially more copies of infectious HIV).

But HIV DNA can also land in the genomic equivalent of a darkened factory storage room nobody goes into—in that case, the virus may be trapped and unable to reactivate. Between these two extremes there are likely a range of possibilities, from HIV DNA being integrated in a spot where the transcription of HIV RNA is likely, to HIV DNA being integrated into a genomic dead end from which it can never emerge. Again, these new findings have implications for latency-reversing agents because they demonstrate that there’s a spectrum of reversibility that will need to be addressed.

The potential importance of where latent HIV resides in a cell’s genome has been emphasized by recent studies of elite controllers (as presented at CROI by Chenyang Jiang), which suggest that their immune responses can clear the more active HIV reservoir, leaving behind only those cells containing HIV integrated in places from which it cannot reactivate—essentially, the intact HIV that remains in their bodies may be trapped, and unable to replicate or cause harm.

A further wrinkle in the latency story is the ability of CD4 T cells containing integrated HIV to proliferate, duplicating the viral genes they contain along with the cell. As Lewin noted, it’s now recognized that a large proportion—typically around half—of the HIV reservoir in people on ART has been created by what is referred to as clonal proliferation of CD4 T cells. The proportion of the HIV reservoir generated by clonal proliferation can be identified because the viruses are genetically identical and integrated into exactly the same spot in the genome of CD4 T cells that contain them.

The mechanisms driving the proliferation of latently infected CD4 T cells are still being elucidated but Lewin listed several possibilities:

• Homeostatic proliferation: this is a normal part of the life of CD4 T cells that facilitates the survival of the cell and maintenance of overall CD4 T cell numbers. Evidence that it plays a role in maintaining the HIV reservoir was first published back in 2009.
• Antigen-specific proliferation: the process by which CD4 T cells proliferate after recognizing a specific antigen (e.g. an antigen derived from HIV or other infectious agents such as CMV) and becoming activated to respond. Lewin cited several studies reporting new data on the importance of antigen-specific proliferation in HIV persistence (including two at CROI: Simonetti et al and Mendoza et al)
• HIV integration site driven proliferation: in this scenario, it’s been proposed that HIV can influence the proliferation of CD4 T cells by integrating into certain places in a cell’s genome. At CROI, John Coffin described findings that may support this possibility, but only for a limited number of integration sites.

There are published studies showing that latently infected CD4 T cell clones contribute to viral load rebound after ART interruption, and also that HIV reservoir activity in these cells can in some cases generate sufficient HIV RNA to be measurable by standard viral load tests (making it necessary for clinicians to be alert to the possibility of mistakenly attributing detectable HIV RNA in people on ART to treatment failure).

The last but critical point made by Lewin about the HIV reservoir is the distinction between intact and defective HIV. It’s been known for some time that the vast majority of HIV DNA present in people on ART represents defective viruses that are incapable of replicating (although in some cases capable of generating viral proteins), but researchers have lacked the tools to easily distinguish replication-competent HIV.

The recently developed intact provirus detection assay (IPDA) is an example of progress on this front. Lewin cited an encouraging new analysis by Gregory Laird and colleagues indicating that levels of intact HIV decline on ART, while the amount of defective HIV DNA remains relatively stable. Based on the case of the elite controller Loreen Willenberg, in whom no intact HIV can be detected, Lewin also suggested that perhaps a cure should be defined as the elimination of all intact virus (rather than the absence of any detectable HIV genetic material).

Moving on to the future of kick and kill, Lewin selected some examples of advances that offer reasons for optimism. Earlier this year, results of an evaluation of the candidate latency-reversing agent AZD5582 were published in the journal Nature. The compound belongs to a class of drugs called SMAC mimetics, which appear to have considerably less potential to cause toxicity compared to the drugs studied to date. In studies in both HIV-infected humanized mice and SIV-infected macaques, potent induction of viral RNA expression was observed in blood and multiple tissues after dosing.

Immunomodulatory compounds such as immune checkpoint inhibitors (e.g. anti-PD1 antibodies that are approved for cancer) and toll-like receptor (TLR) agonists may have the ability to both reverse HIV latency and enhance killing of infected cells. Concerns about serious immune-mediated side effects are currently limiting the use of the former, but might eventually be addressed by different formulations and dosing strategies. Two studies are testing TLR agonists in combination with dual bNAbs (one with the addition of therapeutic vaccination): TITAN and JAWS. Both trials involve ATIs. JAWS is taking place at the University of California San Francisco (UCSF) but was only due to start enrolling very recently (and is not yet registered in clinicaltrials.gov), so may well be delayed by the current COVID-19 emergency.

The field of gene therapy is contributing another kill strategy: Chimeric Antigen Receptor (CAR) T cells, which are genetically modified to efficiently target virus-infected cells for destruction. Blake Rust presented results of a small CAR T cell experiment in SHIV-infected macaques at CROI, which showed some potential to control viral replication—one animal experienced an 89 day delay in viral load rebound after ATI, and two out of the four total animals displayed post-ATI suppression of viral load. Other research groups are also pursuing the idea.

At the Pre-CROI Community HIV Cure Research Workshop—an event co-sponsored by TAG that was held via webinar this year—James Riley described the status of efforts to translate the CAR T cell approach for use in people with HIV. A pilot trial combining CAR T cells with CD4 T cells gene-modified to lack the CCR5 co-receptor is now underway the University of Pennsylvania.

The lack of success observed to date with kick and kill may seem disheartening, but it does not necessarily spell doom—the ever-improving understanding of the biology of HIV latency combined with the expanding array of therapeutic candidates suggests the stubborn persistence of the HIV reservoir can yet be overcome.

Conference Catch Up: HIV Cure Research

A number of conferences and workshops related to HIV cure research have taken place over the past several months, many of which can be viewed or learned about online. Links and some brief reports from four events are provided below.

Promising Approaches to HIV Remission and Cure

HIV cure research was the chosen topic for the Harvard University Center for AIDS Research (CFAR) annual symposium, held on October 23rd. The organizers have created a YouTube playlist featuring all presentations and panel discussions from the event.  

5th Conference on Cell & Gene Therapy for HIV Cure

The only conference that specifically focuses on cell and gene therapy in HIV cure research was launched in 2014 under the auspices of the defeatHIV Collaboratory at the Fred Hutchinson Cancer Research Center in Seattle. The meeting has quickly become established as the key annual get together for this area of the cure research field. The 5th conference took place from August 22-23 in Seattle; the agenda is available on the event website and videos of presentations are now being added to the defeatHIV YouTube channel (a playlist is available for day 1).

Fred Hutch News published two stories about the conference, the first highlighting the work of keynote speaker Dr. Robert Siliciano and the second covering presentations and a workshop focused on strategies to make gene therapies more affordable and globally accessible.

The latter workshop was co-organized by the well-known HIV researcher Mike McCune, who is now leading the HIV Frontiers program at Global Health Innovative Technology Solutions, Bill & Melinda Gates Foundation. McCune recently co-authored a commentary in the journal EBioMedicine outlining how an accessible gene therapy might theoretically contribute to achieving an HIV cure.

A significant step toward making the hope of accessible gene therapies a reality was announced by the Bill & Melinda Gates Foundation and the National Institutes of Health (NIH) on October 23rd. The two research behemoths have joined forces to launch an initiative that will invest at least $100 million over the next four years to develop affordable, gene-based cures for sickle cell disease (SCD) and HIV.

In tandem with the Cell & Gene Therapy conference, defeatHIV’s indefatigable Community Engagement Project Manager Michael Louella organized a public event at the Seattle Library co-hosted by DeAunte' Damper, the LGBTQ Chair of the Seattle King County NAACP. Discussants included the researcher Carl June, gene therapy trial participants Matt Sharp and Matt Chappell, and defeatHIV Community Advisory Board members Tranisha Arzah and Manuel Venegas. Video is available on the Seattle Channel and the defeatHIV YouTube channel.

Finding and Characterizing HIV Reservoirs

A second example of collaboration between the Bill & Melinda Gates Foundation and the NIH in the area of cure research was a workshop on finding and characterizing HIV reservoirs, held July 30-31 on the NIH campus. Thanks to the wonders of the NIH videocast system, the entire meeting can be viewed online (see day 1 and day 2).

Particularly recommended is a tour de force presentation by Robert Siliciano, one of the first researchers to identify the HIV reservoir. Siliciano highlighted the recent shift in understanding of how the HIV reservoir persists despite antiretroviral therapy (ART). Initially, there were suspicions that continuing low-level viral replication in tissues (sometimes referred to as “sanctuary sites”) was playing a role, but it has now become apparent that—in his words— “the vast majority of cells in the reservoir are not generated by direct infection but by proliferation of previously infected cells.”

Siliciano also discussed a new assay developed in his laboratory that attempts to simplify the detection of the replication-competent HIV reservoir. In a study published in Nature earlier this year (now available free in PMC), Siliciano’s group described their approach to assessing the intactness of HIV DNA proviruses, which they’ve named the intact proviral DNA assay (IPDA).

In the workshop presentation, Siliciano showed unpublished data from Gregory Laird indicating that the decay of the HIV reservoir in people on ART is the same (~44 months) when measured with the IPDA or the far more cumbersome and expensive quantitative virus outgrowth assay (QVOA). He noted, however, that the IPDA also revealed outliers around the average value – some study participants had precipitous declines in their HIV reservoir, while others showed increases (likely the result of proliferation of latently infected CD4 T cells).

IAS HIV and HBV Cure Forum/IAS 2019

In recent years, the International AIDS Society (IAS) has scheduled symposiums on HIV cure research immediately preceding their main annual conference (which alternates between the International AIDS Conference and the IAS Conference on HIV Science). The theme differs at each event, and in 2019 the focus was on parallels between the efforts to cure HIV and hepatitis B (HBV).

A detailed report from the meeting was published on October 22nd in the open access Journal of Virus Eradication. Oral and poster abstracts are also available from the same journal. Slide presentations are posted on the IAS website for the event.

Among the presentations:

Maria Pino described research in the SIV/macaque model suggesting that the approved multiple sclerosis treatment fingolimod (trade name Gilenya) can cause retention of cytotoxic T cells in lymphoid tissue and reduce the reservoir of virus DNA in T follicular helper cells (some of the work was published in PLoS Pathogens on October 18th). A subset of macaques administered fingolimod at the time of ART initiation showed evidence of a delayed and lower magnitude viral load rebound after an analytical treatment interruption.

There is considerable interest in the prospects for Gilead Sciences toll-like receptor 7 (TLR-7) agonist vesatolimod in HIV, due to encouraging results in macaques. Preliminary data from a phase I trial in people on ART were presented by Sharon Riddler from the University of Pittsburgh School of Medicine. The compound appeared safe and there was evidence of immune-stimulating activity at doses over 6mg. The ultimate aim is to study vesatolimod in combination with other interventions such as broadly neutralizing antibodies.

One question that the trial didn’t address is whether responses to vesatolimod might be different in women compared to men. A decade ago the research group of Marcus Altfeld reported evidence of sex differences in responsiveness to TLR7 agonists, and female sex was associated with greater induction of interferon-stimulated gene expression in a previous trial of vesatolimod as a treatment for hepatitis B.

Out of 48 participants in the dose-escalating HIV trial, only five were women, and three of the six dose groups included only men. It will be important for future studies to investigate whether sex influences the response to vesatolimod in people with HIV. An ongoing trial is evaluating vesatolimod in HIV controllers who have started ART, but demographic information on participants is not yet available.

Sharon Lewin from the Doherty Institute in Australia described a new effort that is underway to develop a “target product profile” (TPP) for an HIV cure with particular focus on global accessibility, and the formation of a related “HIV Cure Acceleration for Africa” (HCAAP) working group. These plans grew out of a summit hosted by the IAS in partnership with the Annenberg Trust at Sunnylands.

A presentation at the main IAS 2019 conference that drew attention was delivered by Xu Yu from Massachusetts General Hospital. Yu highlighted cases of extreme elite control of HIV that may represent clearance of all replication-competent viruses, focusing in particular on a long-term elite controller referred to as the “San Francisco patient.” Recently, an article in Leapsmag by Bob Roehr revealed the individual to be Loreen Willenberg, who is renowned among activists for her key role in promoting elite controller research via the Zephyr Foundation. Official IAS 2019 video of Yu’s presentation is not available, but a partial recording is posted to the defeatHIV Facebook page.

Links to cure-related IAS 2019 sessions are appended below.

Stem cell and genome editing for HIV cure (plenary session, presentation starts at 0:31:40)
Paula Cannon, University of Southern California, United States

New and old players in HIV replication

HIV transcription: The sound of silence

What is the cure, why do we need it and how do we get there?

Keep control: Elite and post-treatment controllers

Hide and seek: Reservoirs and strategies to target them

Research by and for whom? Community engagement in research

HIV remission and control trials

50 shades of reservoirs

Kill the enemy: CTL and NK cells

Paediatric HIV infection: It's never too early

Pathogenesis: And the band plays on

Mission remission: Challenge accepted

Post-AIDS 2018 Updates on HIV Cure Research

In the aftermath of the 22nd International AIDS Conference (AIDS 2018), which took place in Amsterdam in July, there has been some reflecting on the challenges facing the HIV cure research field. The presentations that garnered the most news coverage described disappointing study results, but there were also nuggets of novelty and encouragement to be found amidst the sea of data on offer (see previous post for links to relevant conference sessions, many of which now have video and/or slides available).

The RIVER Trial

The most widely reported findings came from a clinical trial in the UK known as RIVER (Research In Viral Eradication of HIV Reservoirs). Participants with primary HIV infection were randomized to receive a standard antiretroviral therapy (ART) combination plus the integrase inhibitor raltegravir or ART plus raltegravir along with a therapeutic HIV vaccine regimen and a short course of the HDAC inhibitor vorinostat (a candidate HIV latency-reversing agent). The primary purpose was to evaluate whether the vorinostat and vaccine combination—a version of the proposed “kick & kill” approach to depleting the HIV reservoir—had a significant effect on HIV reservoir measures compared to ART.

As described in detail in multiple online reports (e.g. see i-Base, AIDSMap, and the Imperial College website), the size of the HIV reservoir—as assessed by both total HIV DNA and the viral outgrowth assay—remained equivalent between the two arms. Presenter Sarah Fidler pointed out some possible caveats, such as the relatively short follow up time, but the data appear to rule out any significant effect by this particular kick & kill combination.

The researchers cited several potential explanations: the latency-reversing activity of vorinostat may be suboptimal, and there is uncertainty as to whether the HIV-specific T cell responses that were successfully induced by the vaccines were targeting parts of the virus most likely to be displayed by infected cells after latency reversal. As is emphasized in much of the coverage, the study itself should not be considered a failure because it provided a clear answer to the question it was designed to address. The interventions were also found to be safe and no participants withdrew.

The results echo a theme that has been sounding recently in HIV cure research: randomized controlled trials are required to rigorously evaluate the potential of candidate interventions, and positive results from single-arm exploratory trials (which tend to compare results to baseline values or historical controls) need to be interpreted with caution.

Studies published over the past year that have reached a similar conclusion include randomized controlled evaluations of a therapeutic vaccine combination and single doses of the candidate latency-reversing agent romidepsin.

Vedolizumab

The second piece of unwelcome news related to vedolizumab, an antibody that targets the α₄β₇ integrin, a protein involved in CD4 T cell trafficking to the gut that may also facilitate HIV entry into target cells. In 2016, an experiment in SIV-infected macaques generated excitement when administration of a version of vedolizumab adapted for macaques (see comment by Robert Reinhard below) was associated with control of viral load after ART interruption. Human trials were initiated relatively quickly because vedolizumab is already FDA approved as treatment for ulcerative colitis and Crohn's disease.

During a talk at the conference on HIV remission, Anthony Fauci from the National Institute of Allergy and Infectious Diseases (NIAID) provided a glimpse at the data from the first of these trials, and sadly the results did not mirror the published macaque study. While it appeared that one or two participants displayed some evidence of viral load containment after an analytical treatment interruption (ATI), the majority did not.

Fauci suggested the variations in viral load levels were similar to those his group has observed in placebo recipients in prior trials, and were not indicative of any effect from vedolizumab. At least two other clinical trials involving the antibody are ongoing, so additional results will be forthcoming.

In a separate presentation, Michele DiMascio put another dent in the optimism that had surrounded vedolizumab by reporting that an attempt to repeat the original results obtained in SIV-infected macaques had failed. This time, there was no evidence of antibody-induced SIV control. The reasons for the divergent outcomes are unclear, but may relate to the type of SIV used in the experiments, which has a mutation in the nef gene (update 3/21/19: the journal Science has now published an "editorial expression of concern" about the original study).

Reservoir Targeting

A number of presentations described novel approaches for targeting the HIV reservoir, highlighting the amount of work that is underway to try and improve upon the interventions tested to date.  

Isa Munoz-Arias and colleagues from UCSF and Merck reported that a number of FDA-approved chemotherapeutic drugs have HIV latency-reversing activity in laboratory studies. In some cases the magnitude of the effect was demonstrated to be greater than the combination of bryostatin and romidepsin, which has previously been shown to be among the most potent latency-reversing strategies in vitro. The effects were not associated with significant T cell activation or CD4 T cell death (although it’s important to note that this does not mean the drugs are without side effects - those are described on their labels).

A total of 12 FDA-approved chemotherapies were found to reverse HIV latency via a variety of novel pathways, suggesting new avenues for exploration beyond the current candidates, which primarily comprise HDAC inhibitors. The details of the presentation can be found on Jules Levin’s NATAP website (which often does more to make information public than conferences themselves), and it was also covered by Simon Collins for i-Base.

The research group of Wen Kang debuted data from a small, uncontrolled pilot study of the HDAC inhibitor chidamide, which is approved in China as a cancer therapy. Kang described evidence that the drug had stimulated production of HIV RNA in seven individuals on ART, and may have slightly reduced HIV DNA levels. However in the Q&A after the talk Sharon Lewin noted that the various possible markers of activity that were analyzed did not appear to necessarily correlate with each other. A larger randomized controlled trial that should provide more definitive results is now ongoing.

Tim Henrich from UCSF followed up on work published earlier this year in PLoS Pathogens identifying CD30—a cell surface molecule known for its association with lymphoma—as preferentially expressed on HIV-infected CD4 T cells.

In the paper, the researchers describe an individual with HIV who exhibited undetectable viral RNA and DNA levels after receiving therapy for lymphoma including brentuximab vedotin, an anti-CD30 antibody-drug conjugate. Unfortunately the individual died after cancer recurrence so no further investigation was possible.

Henrich's conference abstract reports the identification of a second person with HIV who received brentuximab vedotin as part of treatment for lymphoma (now in remission). Three weeks after administration of the first dose, HIV RNA was reduced to undetectable from a previous level of 7,359 copies per million CD4 T cells (a greater than 3 log reduction). HIV DNA levels fell by 42%. The individual is now being followed longitudinally.

This research opens up the possibility of targeting CD30 as a means to deplete the HIV reservoir, and in addition to brentuximab vedotin there are also CD30-specific chimeric antigen receptor (CAR) T cells in development that are already being studied in clinical trials for cancer.

An interesting presentation by Sarah Joseph from the University of North Carolina at Chapel Hill outlined an effort to establish when viruses enter the latent reservoir. Using complex phylogenetic analyses (see the abstract for an example), Joseph uncovered evidence that in most individuals studied, the majority (~72%) of the replication-competent latent HIV reservoir was most closely related to viruses circulating in the year prior to ART initiation. In contrast, only 5% was derived from virus replicating during the first year of infection.

A paper published in the journal eLife in 2016, involving ten participants, reported similar results, although Joseph also pointed out that a much smaller study presented at the conference by Zabrina Brumme (subsequently published in PNAS) reached different conclusions, finding more diverse dates of establishment of the reservoir.

Joseph’s data suggests that latently infected cells tend to be shorter-lived during untreated infection, with ART initiation triggering the formation of the bulk of the long-lived HIV reservoir. The implication for therapeutic strategies targeting the reservoir is that there might be a window of opportunity to intervene at the time ART is started (currently, almost all clinical trials involve testing candidate therapies in individuals after ART has suppressed viral load). This idea could potentially be explored in the SIV/macaque model.

HIV Control Off ART

Participants in the VISCONTI cohort represent the best known and most widely cited examples of post-treatment control of HIV replication. In 2013, when Asier Sáez-Cirión and colleagues published a detailed report in PLoS Pathogens, the cohort comprised 14 individuals. Updates have been fragmented since that time, occurring at various conferences, and as yet there have been no follow up publications as thorough as the original paper (at least that I’m aware of - for the sake of disclosure I should note that I chided the investigators about this situation in a public comment to the PLoS Pathogens article in 2017).

At AIDS 2018, Laurent Hocqueloux and colleagues presented a poster on factors associated with loss of post-treatment controller status that included an update on the VISCONTI cohort. The study also offered results from analyses of inflammatory biomarkers, which I’ve not seen described previously.

A total of 24 post-treatment controllers have now been added to the VISCONTI cohort; all started ART during primary infection and then interrupted after a median of 3.5 years of treatment. During subsequent follow up (current median of 12 years), five (21%) have restarted ART, four due to increasing viral load and one as a result of a head and neck cancer diagnosis.

These five participants were among seven who experienced one or more viral load measurements above 400 copies/ml during monitoring; none of the 17 who remained below this viral load level restarted ART (a highly statistically significant difference). The fact that the individual who developed cancer was in the former group, despite not reinitiating ART based on viral load criteria, may raise concern that prior exposure to detectable HIV viremia was a risk factor for cancer development. Whether remaining on ART would have been associated with lower risk is an unanswerable question. This conundrum illustrates that firm conclusions about the clinical benefits of post-treatment control compared to continuous ART cannot be drawn until post-treatment control can be induced in sufficient numbers of people to allow a randomized comparison.

Overall, CD4 counts and CD4:CD8 ratios have remained stable in the cohort with medians not significantly different between the time of ART interruption and last follow up. Individual plots are not shown in the poster, however, so it’s unclear if declines occurred in participants who experienced viral load increases.

Encouragingly, the majority of VISCONTI cohort members have maintained viral loads below 50 copies/ml, and levels of three inflammatory biomarkers—IP-10, sCD163 and sCD14—were not significantly different between these post-treatment controllers and healthy HIV-negative individuals (see figure 6 in the poster).

In a separate oral presentation, Asier Sáez-Cirión showed evidence that certain immune response genes are associated with post-treatment control in the VISCONTI cohort, and may be mediating their effects—at least partly—through superior natural killer (NK) cell activity against HIV (unfortunately neither slides or video of this presentation are available on the conference website).

Lisa Chakrabarti described an investigation of potential mechanisms of HIV control in a different population: elite controllers participating in the ANRS CODEX cohort. The researchers focused on HIV Gag-specific CD4 T cell responses, and found that CCR5 expression was lower among elite controllers compared to a control group of people with HIV on ART. 

The lower CCR5 expression by Gag-specific CD4 T cells was associated with reduced susceptibility to HIV infection, suggesting this may contribute to elite controller status. The results may offer support to efforts to protect virus-specific CD4 T cells from HIV infection using gene therapies that ablate CCR5 expression (or otherwise attempt to protect the cells from HIV entry), an approach being pursued by researchers at the defeatHIV collaboratory.

Analytical Treatment Interruptions (ATIs)

A controversial component of research working toward achieving post-treatment control of HIV is the use of ATIs. A systematic review of past studies involving ART interruptions could help shed light on the safest approaches to conducting ATIs in clinical trials, and Jillian Lau and colleagues from Alfred Hospital and Monash University in Melbourne, Australia delivered just such a review as a poster presentation at the conference. Their work is now in press at a journal and will hopefully be published soon.

Online Post-Conference Coverage

As is always the case, an array of excellent reporting has become available online since the conference. See below for a selection; please leave a comment if you know of coverage I’ve missed that should be included.

AIDS 2018 HIV Cure Research Highlights - Karine Dubé and Jeff Berry, Positively Aware

The Road Ahead for HIV Cure Research - Benjamin Ryan, POZ Magazine, September 6, 2018

Cure Updates from AIDS 2018 - hivcure.com.au/Doherty Institute

AIDSMap

i-Base

NATAP

Elite Controllers: Sex Differences and Factors Associated with Loss of Immune Control

Over the past few months, several interesting papers addressing elite control of HIV infection have seen publication. The ability of elite controllers to maintain undetectable viral loads and relatively preserved CD4 T cell counts in the absence of ART has led them to be proposed as a model for a functional cure of HIV infection. But there is also evidence that many elite controllers exhibit elevated levels of inflammation compared to HIV-negative counterparts, and eventually experience disease progression, leading some researchers to call this proposition into question. The uncertain relevance of elite control to HIV cure research is prompting studies that attempt to parse the factors distinguishing individuals who preserve elite controller status from those who ultimately progress.

In the journal eBioMedcine, Wang Zhang and colleagues explore the expression of a variety of genes and proteins in a cohort of 19 elite controllers, compared to 32 individuals with progressive HIV infection and 23 healthy HIV-negative controls. Of particular note, nearly half the elite controllers (9) were women, allowing the researchers to compare results based on sex. The authors point out that several previous studies have reported that women tend to be overrepresented among elite controllers (e.g. see Crowell et al and de Azevedo et al).

A potentially important finding is that the gene expression profiles of female elite controllers were similar to HIV-negative females, but there were significant differences between male elite controllers and HIV-negative male controls. A potential implication is that women will be more likely to maintain elite controller status over time compared to men—this possibility will need to be investigated further. 

Among the differences observed in elite controllers compared to individuals with progressive HIV infection were downregulation of the genes for CXCR6 and SIGLEC1. The authors explain that these differences could be associated with decreased susceptibility of CD4 T cells for HIV entry and reduced cell-to-cell virus transmission mediated by myeloid cells.

Levels of the chemokine CCL4 (MIP-1β) were found to be higher among elite controllers versus progressors, consistent with a previous study. Conversely, levels of the inhibitory immune cell receptor PD-1 (and its ligand PD1-L2) were significantly lower, echoing another recent paper reporting lower levels of multiple inhibitory receptors in elite controllers.

BMC Medicine has published an analysis by José Benito and colleagues that looks at possible contributors to loss of elite control. The researchers evaluated 36 elite controllers followed for approximately a decade on average, comparing multiple immunological parameters between those with stable CD4 T cell counts (n=22) and those exhibiting significant CD4 T cell decline during the follow up period (n=14). Interestingly, women made up 67% of the former group but only 31% of the latter, a statistically significant difference (p=0.04). The authors don’t offer any comment on this apparent overrepresentation of women in the group of elite controllers with stable CD4 T counts.

Many immunological variables were found to differ between elite controllers and HIV-negative healthy controls, as well as between stable elite controllers and those experiencing CD4 T cell declines. Distinctions between elite controllers and HIV-negative healthy controls included lower levels of several T cell subsets: naïve, recent thymic emigrant, stem cell memory, and regulatory. Expression of the T cell costimulatory receptor CD28 was lower, whereas CD95—involved in apoptotic cell death—was increased.

Comparisons between the stable elite controllers and progressors revealed that the latter group had lower levels of naïve and recent thymic emigrant CD8 T cells, as well as higher levels of CD8 T cells with effector memory and senescent phenotypes. The finding suggests that CD8 T cells may have been differentiating at a higher rate in this group—in other words, naïve CD8 T cells were more frequently becoming activated and transitioning into memory cells (perhaps reflective of a more strenuous battle to keep HIV contained). The progressor group also showed increased expression levels of PD-1 in both total CD4 T cells and the central memory CD4 T cell subset.

In a separate study published in the Journal of Virology earlier this month, María Pernas and colleagues conducted a retrospective, longitudinal analysis of factors contributing to loss of viral load suppression in a cohort of elite controllers. A total of 31 elite controllers were included, defined based on having viral load below detectable levels (50 copies/ml) on three consecutive measures over a year of follow up.

Fourteen of these individuals subsequently experienced increases in viral load (two consecutive measures above the detection limit within a year), and were classified as transient controllers. The remaining 17 maintained undetectable viral loads and were classified as persistent controllers. Sex differences were not apparent in this study, with women making up 43% of the former group and 41% of the latter. The only significant differences were for time since diagnosis (averaging 8 years and 18 years, respectively) and sexual transmission as mode of HIV acquisition (71% vs. 35%).

The availability of samples prior to the viral load increases in the transient controller group allowed several factors associated with the loss of HIV suppression to be identified. CD8 T cells targeting the HIV Gag protein were found to be significantly less polyfunctional (assessed based on production of the cytokines IFN-γ, TNF-α and IL-2) and displayed a more activated phenotype a year prior to viral load becoming detectable. HIV genetic diversity within the env gene was also significantly higher, with a similar trend observed for the gag gene. In contrast, persistent controllers showed little or no evidence of ongoing viral evolution.

Inflammatory biomarkers were elevated in the transient controllers. and an analysis of 70 different cytokines and chemokines in plasma samples revealed that increased levels of RANTES and Platelet Derived Growth Factor (PDGF) AA were the best predictors of subsequent loss of elite controller status. RANTES in particular showed a strong association, being an average of four-fold higher in transient controllers.

In discussing their results, the authors emphasize the importance of focusing on examples of strict, persistent control of HIV if the goal is to identify “the right model of functional remission.” They also suggest that factors strongly predictive of future viral load rebound—such as RANTES levels—might have the potential to help discriminate elite controllers likely to benefit from ART from those who may not require it.

Similar points are made in a commentary in EBioMedicine by Laura Tarancon-Diez and colleagues. The commentary accompanies a paper describing an elite controller who has maintained extremely low levels of HIV RNA and HIV DNA for a decade, without fully seroconverting on the Western Blot antibody assay. Evidence of polyfunctional HIV-specific CD8 T cell responses and strong antibody-mediated cellular cytotoxicity (ADCC) by natural killer cells is reported. The individual acquired HIV from a partner who was not able to control the same CRF02_AG virus variant. Neither partner possesses known favorable HLA alleles although both are heterozygous for the CCR5Δ32 mutation.

The commentary also cites work published last year from the French CODEX cohort, which described a subset of HIV controllers in whom viral load had never been detectable using routine assays during an average of 18 years of follow up. In a comparison with controllers who had experienced viral load blips, T cell counts were reported to be stable (as opposed to progressively declining), and this was accompanied by lower T cell activation and HIV DNA measurements. This study also showed a trend toward an overrepresentation of women in the persistently undetectable group (34 out of 52, 65%) versus the viral load blips group (90 out of 178, 51%, p=0.06).

Tarancon-Diez and colleagues advocate concentrating on “this very scarce proportion of individuals that are able to persistently control the virus” in order to inform the design of cure strategies aiming to induce long-term remission in the absence of ongoing ART.

Whether there might be particular features of the immune response (or other factors) in women that increase the likelihood of persistent elite control needs to be elucidated. Ongoing work is investigating possible differences related to HIV persistence in women receiving ART, with Eileen Scully presenting the latest findings from her research as a poster at the CROI 2018 conference. Scully has uncovered a number of significant sex-based associations, including higher expression of several antiviral genes.

As Zhang and colleagues argue in the closing section of their EBioMedicine paper: "Despite extensive data on the male and female difference on disease outcome, research does not sufficiently take gender into account. Altogether, our study showed that it would be important to carefully consider gender in cohort design for future transcriptomic and intervention studies on HIV-1 patients."

New Case of “Remission” Reported in a Perinatally Infected Teenager

A new example of long-term post-treatment control of HIV viral load was reported this past Monday at the 8th IAS Conference on HIV Pathogenesis, Treatment and Prevention (IAS 2015) in Vancouver, attracting widespread media attention. Presented by Asier Sáez-Cirión from Institut Pasteur in France, the case involves a teenager who acquired HIV infection perinatally and was taken off ART at around the age of six, subsequently maintaining very strict control of viral load for over 12 years and counting (the slide presentation is now posted online). Sáez-Cirión is also the lead investigator for the well publicized VISCONTI cohort, a group of early-treated adults who are exhibiting long-term of HIV viral load after ART interruption (described in some detail in a paper in 2013, at which time the cohort had 14 members, and recently reported to now number 20 with an average time off ART of over nine years. Update 7/25/15: the status of several VISCONTI cohort participants has changed, see addendum below). 

The new case was discovered as a result of an analysis of the French National Agency for AIDS Research (ANRS) pediatric cohort study, which has been following over 10,000 mother-child pairs sine 1986. A total of 100 infants were identified who had begun ART within six months of birth and, of those, 15 had interrupted treatment after an average of 33 months. Only two of the 15 showed evidence of control of viral load: one for around three years before viral load climbed above 500 copies, the other on an ongoing basis, making her the subject of further investigation.

Records showed that the mother had advanced disease at the time of birth, with a viral load of 4.63 million copies and a CD4 count of 81. The baby received six weeks of AZT monotherapy in an unsuccessful attempt to prevent infection, after which HIV viral load became detectable and rose to 2.17 million copies leading to the initiation of ART consisting of AZT, ddI, 3TC and ritonavir (the AZT was later dropped from the regimen due to side effects). Viral load was suppressed but briefly rebounded during two periods of nonadherence, to 75,190 and 97,000 copies, respectively.

In an echo of the Mississippi baby case, the child was lost to follow up between 5.8 and 6.8 years of age. On return to care, it was learned that ART had been stopped several months previously, but viral load remained below 50 copies. During continued follow up, viral load has stayed undetectable with the exception of two readings, one a little over 500 copies at age 11 and another of 48 copies at age 14 (close to the borderline of the more sensitive assay used at that time).  Recently, ultrasensitive tests capable of detecting as few as 4 copies of HIV RNA per milliliter of blood have been employed, with no positive results recorded. The CD4 percentage is reportedly within the normal range for a comparable HIV-negative person. The individual is now 18.5 years old. The researchers have tested for the presence of ART in plasma samples to formally rule out any possibility of undisclosed usage, and these tests were all negative.

HIV reservoir measurements revealed that HIV DNA is present at around 125 - 316 copies per million CD4 T cells, and low levels of replication-competent virus were detected in samples of purified CD4 T cells after stimulation. HIV-specific CD8 T cells were detectable but were of a low magnitude, and no evidence of CD8 T cell-mediated suppression of HIV replication was observed in a laboratory assay. No data on HIV-specific CD4 T cell responses are available as yet—notably, a poster at IAS 2015 reported that VISCONTI cohort members have “robust” HIV-specific CD4 T cell responses, challenging the widely held view that anti-HIV immunity in these individuals is unusually weak (abstract appended below, an earlier version of the study was presented at CROI 2014)). No immune response genes known to be associated viral load control were present in the individual and they were homozygous for several HLA alleles, a phenomenon that has been associated with a greater risk of rapid progression in HIV in the absence of treatment. Analyses of inflammatory biomarkers have not been conducted yet (to the best of my knowledge, no data on inflammatory biomarkers in VISCONTI cohort members has been presented either).

As with the published paper on the VISCONTI cohort, Sáez-Cirión and colleagues were careful to use the term “virological remission” to describe the outcome in their IAS 2015 abstract describing the case. Although the distinction may seem subtle, this is not necessarily synonymous with just “remission” (the term used in most of the news reports), which is generally interpreted as meaning remission from any increased risk of disease. At the current time, it is not actually known for sure if the low levels of HIV present in these post-treatment controllers are associated with a long-term health prognosis that is similar to, better, or worse than a comparable HIV-positive individual whose virus is suppressed by ART. As covered in a recent blog post, there are some reasons to be concerned that the HIV suppression in at least some of these cases may not have equivalent health benefits to that achieved by ART.  

The researchers have also stressed that post-treatment control is an extremely rare phenomenon and that ART should not be interrupted outside of clinical trials at this time. There have been many published studies of ART interruptions in children and adolescents, some including quite large numbers of participants, but examples of even short-term post-treatment control are few and far between. Examples in the scientific literature include a teenager who maintained undetectable viral load for over five years after stopping ART; however there was no documented history of high viral load prior to treatment and they were found to be heterozygous for the CCR5-Δ32 mutation. Another paper mentions one participant whose viral load stayed below 400 copies for one year after ART interruption, but no further details are provided. The majority of children in these studies experienced viral load rebound and CD4 T cell loss as a result of treatment cessation.

The new case adds to the evidence that early ART is beneficial and may, in rare instances, facilitate long-term control of viral load after treatment interruption. Ongoing and planned trials in both children and adults aim to carefully investigate the extent to which virologic remission might be achieved by this strategy. Researchers are also exploring early ART combined with additional interventions such as latency-reversing agents and immunotherapies with the aim of increasing the likelihood of virologic remission.

Addendum 7/25/15, VISCONTI cohort update:  Asier Sáez-Cirión's slide presentation has now been posted on the International AIDS Society's Towards an HIV Cure Symposium website (along with the other materials from the meeting, which took place in Vancouver on July 18 & 19, immediately prior to IAS 2015). At the end, the slides include an important update on the current status of VISCONTI cohort participants. Of the 14 individuals described in the 2013 PLoS Pathogens paper, one has experienced a viral load rebound (reaching close to 100,000 copies) after six years off ART, necessitating reinstitution of treatment. Another has persistently detectable viral load (in the 100-1,000 copy range) and a declining CD4 T cell count that is now below 500 cells. A third is reported to have developed "ORL cancer" (which I believe refers to head and neck cancer), and resumed treatment. Lastly, a fourth member of the original 14 is lost to follow up. Of the remaining 10, nine continue to be followed with undetectable viral load while one had a viral load level of 211 copies at the time of the last measurement. 

The last slide of the presentation notes that six additional post-treatment controllers have been added to the VISCONTI cohort (explaining the reference to a total of 20 individuals in Sáez-Cirión's latest published review from earlier this year), but no details on their viral loads and CD4 T cell counts are provided. A graph is shown for one of the new additions who, like several of the initial cohort members, possesses the HLA B*35 allele; the viral load in this individual appears to be well-controlled off ART but the CD4 T count is below 400. Hopefully these updated findings will be fully disclosed and discussed soon.

8th IAS Conference on HIV Pathogenesis, Treatment and Prevention (IAS 2015), Vancouver, Canada, July 19-22, 2015

MOAA0105LB Oral Abstract 

HIV-1 virological remission for more than 11 years after interruption of early initiated antiretroviral therapy in a perinatally-infected child

P. Frange1,2,3, A. Faye4,5, V. Avettand-Fenoel1,2, E. Bellaton6, D. Deschamps7,8, M. Angin9, S. Caillat-Zucman10,11, G. Peytavin12,13, J. Le Chenadec14,15, J. Warszawski14,15, C. Rouzioux1,2, A. Saez-Cirion9, ANRS EPF-CO10 Pediatric Cohort 

1Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital Necker - Enfants malades, Laboratoire de Microbiologie clinique, Paris, France, 2EA7327, Université Paris Descartes, Paris, France, 3AP-HP, Hôpital Necker - Enfants malades, Unité d'Immunologie, Hématologie et Rhumatologie pédiatriques, Paris, France, 4AP-HP, Hôpital Robert Debré, Service de Pédiatrie générale, Paris, France, 5Université Paris 7 Denis Diderot, Paris, France, 6AP-HP, Hôpital Robert Debré, Service d'Hématologie pédiatrique, Paris, France, 7AP-HP, Hôpital Bichat - Claude Bernard, Laboratoire de Virologie, Paris, France, 8INSERM UMR1137 IAME Université Paris Diderot, Paris, France, 9Institut Pasteur, Unite de HIV inflammation et persistance, Paris, France, 10AP-HP, Hôpital Robert Debré, Laboratoire d'Immunologie, Paris, France, 11INSERM UMR1149, Université Paris Diderot, Paris, France, 12AP-HP, Hôpital Bichat, Laboratoire de Pharma-Toxicologie, Paris, France, 13IAME, INSERM UMR 1137, Université Paris Diderot, Paris, France, 14AP-HP, Hôpital Bicêtre, Service d'Epidémiologie et de Santé publique, Le Kremlin-Bicetre, France, 15INSERM U1018, Université Paris Sud, Le Kremlin-Bicetre, France

Background: Durable HIV-1 remission after interruption of combined antiretroviral therapy (cART) has been reported in some adults who started cART during primary HIV-1 infection. The in utero HIV-1-infected «Mississippi child», exhibited transient viral control after interrupting very early-initiated cART. However viremia rebounded 27 months later, leaving unclear the possibility of obtaining long-term post-treatment remission in vertically-infected children. Here we report the case of a perinatally-HIV-1-infected adolescent who shows unprecedented virological remission more than 11 years after cART discontinuation.

Methods: HIV-RNA and CD4+ T-cell counts have been monitored since birth. Ultrasensitive HIV-RNA, PBMC-associated HIV-DNA, flow-cytometry-assessed frequency of HIV-specific CD8+ T-cells, CD8+ T-cell mediated HIV-suppression, reactivation of the CD4+ T-cell reservoir were evaluated after 10 and 11 years of control off therapy. Plasma concentrations of antiretrovirals were determined by tandem mass spectrometry.

Results: One infant born from a woman with uncontrolled HIV-1 viremia received zidovudine-based prophylaxis during 6 weeks. HIV-RNA and DNA were not detected 3 and 14 days after birth. HIV-DNA was detected at 4 weeks of age. HIV-RNA reached a peak of 2.1x106 copies/ml at 3 months of age when cART (zidovudine, lamivudine, didanosine, ritonavir) was initiated. HIV-RNA was undetectable one month later and remained below assay-detection limits while on cART, except at 15 and 21 months of age. Between 5.8 and 6.8 years of age cART was discontinued by the family. HIV-RNA was undetectable at 6.8 years of age and cART was not resumed. HIV-RNA has remained < 50 copies/ml through 18.3 years of age, except for one blip (515 copies/ml). CD4+ T-cell counts remained stable. After 11 years of control off therapy (confirmed by undetectable plasma concentrations of antiretrovirals), HIV-RNA was below 4 copies/ml and HIV-DNA was 2.2 Log copies/106 PBMC. Low levels of HIV-RNA and p24 were detected upon activation of CD4+ T-cells with PHA. HLA genotype showed homozygosity at several loci (A*2301-;B*1503/4101;C*0210/0802;DRB1*1101-;DQB1*0602-). HIV-specific CD8+ T-cell responses and T-cell activation were very weak. HIV-1 western blot was positive with absence of antibodies against gp110 and p18.

Conclusions: This case provides first-time evidence that very long-term HIV-1 remission is possible in perinatally-infected-early-treated children, with similar characteristics as reported in adult post-treatment controllers.

TUPEA093 - Poster Exhibition

Robust HIV-specific T cells in post-treatment controllers from the VISCONTI cohort

A. Samri1, V. Avettand-Fenoel2,3, L. Hocqueloux4, C. Bacchus-Souffan5, A. Cheret6, A. Emarre7, B. Descours8, A. Saez-Cirion9, C. Rouzioux2,3, B. Autran10,11, VISCONTI Study Group

1Centre d'Immunologie et Maladies Infectieuses, UMR-S Inserm UPMCU 1135, Paris, France, 2Paris-Descartes University, Sorbonne Paris-Cité, Virology Laboratory, EA 3620, Paris, France, 3Necker Enfants-Malades Hospital, Virology Laboratory, Paris, France, 4Regional Hospital Center, Infectious and Tropical Diseases Department, Orléans, France, 5Université Pierre et Marie Curie, Sorbonne Universités, Centre d'Immunologie et Maladies Infectieuses, CIMI, UMR-S 1135, Paris, France, 6CHU Druon, Infectious Diseases Department, Tourcoing, France, 7Université Pierre et Marie Curie, Centre d'Immunologie et Maladies Infectieuses, CIMI, UMR-S 1135, Paris, France, 8Université Pierre et Marie Curie, Laboratoire Immunité et Infection UMR-S-945, Paris, France, 9Institut Pasteur, Unité de Régulation des Infections Rétrovirales, Paris, France, 10Université Pierre et Marie Curie, Sorbonne Universités, Centre d'Immunologie et Maladies Infectieuses, CIMI, Paris, France, 11Pitié-Salpétrière, C. Foix University Hospital, AP-HP, Immunology Department, Paris, France

Background: Post-Treatment-Controllers (PTCs) represent models of functional HIV remission with an exceptional HIV control years after interruption of an early-initiated antiretroviral therapy. The enrichment in the HLA-B35 allele, associated with symptomatic primary-infection and poor prognosis, instead of the protective HLA alleles reported in Elite Controllers (ECs) questions the role mechanism of this HIV control and the role of anti-HIV T cell responses, particularly those driven by HLA-B35. We therefore compared the PTCs HIV-specific CD4 and CD8 T cells to those from continuously early-treated patients (CETs) and ECs.

Methods: We included 12 PTCs from the VISCONTI study*, half HLA-B35+, 10 CETs under a cART initiated within 10 weeks post-infection and 8 ECs from the ANRS-Co15 cohort. Multiparametric flow-cytometry assessed HIV-specific IFNg, IL2, TNFα, MIP1β or CD40L producing CD4 and CD8 T cell stimulated with HIV-p24 protein and peptides. The cell-associated HIV-DNA was measured in PBMCs and naïve and memory sorted resting CD4 T cell subsets.

Results: High frequencies of HIV-p24 specific CD4+ cellswere observed in PTCs and did not differ from the ECs or CETs ones. A third of these PTCs HIV-p24 specific CD4 cells were highly polyfunctional producing 2, 3 and 4 functions, similarly to from CETs and ECs. HLA-B35 did not influence these results. In contrast frequencies of PTCs CD8+ cells producing against HIV-p24 peptides IFNg (p=0.015) or MIP1b (p=0.001) were lower than ECs but equivalent to CETs ones, without differences in poly-functionality between the 3 groups. Among the functions tested here-in there were 20-fold less IFN-g producing HLA-B35+ CD8 T cells than HLA-B35- ones (0.006% versus 0.130%, p=0.041) against HIV-p24 peptides.

Conclusions: The model of HIV remission represented by VISCONTI PTCs is characterized by robust polyfunctional HIV-specific CD4+ T cells similar to those from Elite Controllers and from continuously early-treated patients, independently from the HLA-B35 allele which negatively impacts IFN-g producing CD8 T cells. These results illustrate differences between ECs and PTCs linked to HLA background and suggest early initiation of treatment allows maintenance of robust HIV-p24 specific CD4 T cells in PTCs.

Perspectives on Post-Treatment Control of HIV

Several recent papers offer perspectives on the possibility of achieving post-treatment control of HIV replication by starting antiretroviral therapy (ART) during acute infection. Interest in this topic has been sharpened by reports about the VISCONTI cohort, a group of individuals in France who all started ART soon after HIV acquisition, maintained treatment for several years, then interrupted and are now controlling viral load to very low or undetectable levels. At the time of the last published update, the VISCONTI cohort included 20 individuals (identified from various trials) who have been off ART for an average of nine years.

In a paper titled “How often does treatment of primary HIV lead to post-treatment control?” in Antiviral Therapy, Janine Maenza and colleagues identify 22 individuals who started ART during acute infection (within 12 weeks of acquisition), continued for at least 11 months, then interrupted. Out of this group, only one individual with a low viral load of 2,248 copies at the time of ART initiation maintained viral load below 500 copies for three years after interruption. The viral load then rose to levels similar to baseline for the following three years.  The researchers state: “given our single controller’s relatively low HIV-1 RNA levels during primary infection…we question whether he might have become a natural controller, regardless of initiation of early therapy.”

A study led by Antoine Chéret, published in the Journal of Antimicrobial Chemotherapy, primarily set out to evaluate the size of the HIV reservoir in different CD4 T cell subsets in 11 participants from the OPTIPRIM clinical trial, who began ART an average of 36 days after becoming infected and maintained treatment for at least two years. But the authors note that two individuals in this study displayed control of viral load after ART interruption; in one case the level was consistently below 20 copies for 24 months, in the other there was a rebound followed by control to low but detectable levels (530 copies after 18 months off treatment). The case involving stricter containment of HIV replication showed traits similar to VISCONTI cohort members: high viral load and low CD4 T cell count prior to ART initiation, possession of the HLA B*35 allele that has been associated with faster disease progression in some studies, and low HIV DNA levels, particularly in naïve and central memory CD4 T cells. Also mirroring the VISCONTI cohort, HIV-specific CD8 T cell responses appeared weak and were not able to suppress viral replication in a laboratory assay. 

A third paper by Jessica Conway and Alan Perelson attempts to mathematically model the parameters that might contribute to post-treatment control, and suggests that both the HIV reservoir size and the strength of the HIV-specific cytotoxic T-lymphocyte (CTL) response may be important. The authors explain that the model is relatively simple and that other types of immune responses weren’t considered but could play a role, such as natural killer (NK) cells, CD4 T cells and antibodies. A forthcoming AIDS Clinical Trials Group (ATCG) study is mentioned that plans to evaluate whether the size of the HIV reservoir correlates with time to viral load rebound after ART interruption, as the model predicts (ACTG A5345).

An overarching and extremely important question relating to post-treatment control is not discussed in any of the papers: namely, whether the degree of HIV suppression in post-treatment controllers is equivalent to that achieved by ART when it comes to clinical outcomes. Conway and Perelson write that post-treatment control “corresponds to functional cure, sustained remission that does not require therapy,” but it isn't yet known if this is true. It has become apparent in recent years that elite controllers, who show similar suppression of viral load in the absence of treatment, can ultimately lose CD4 T cells and progress to AIDS (perhaps best documented in an analysis of a large cohort of HIV-positive individuals that was published in PLoS One last year).

The majority of elite controllers also show elevated levels of immune activation, inflammatory biomarkers, and lymph node fibrosis compared to similar HIV-negative individuals. A study presented at CROI last year, and published in January in the Journal of Infectious Diseases, found that elite controllers have higher hospitalization rates compared to HIV-positive individuals on ART, primarily due to cardiovascular disease (although there are some concerns about the influence of confounding variables in this analysis, as described in an excellent AIDSMap article on the paper by Gus Cairns). Furthermore, there is evidence that ART may benefit at least some elite controllers, reviewed recently in the new open access Journal of Virus Eradication by Trevor Crowell and Hiroyu Hatano.

The fact that some post-treatment controllers appear to have weaker HIV-specific T cell responses than elite controllers might suggest that immune activation and inflammation levels are likely to be lower, but there is a lack of data addressing this issue. The main published paper on the VISCONTI cohort only compares immune activation levels to individuals on ART, reporting that they are similar, and there is no comparison to HIV-negative individuals or elite controllers (there is a comparison to a group defined as "HIV controllers" with viral loads below 400 copies, as opposed to the threshold of 50 copies generally used to define elite control). To my knowledge, no data on inflammatory biomarker levels has been presented or published, even though this was one of the questions posed to the investigator Asier Sáez-Cirión when he first described the VISCONTI cohort at a conference several years ago.

The point of raising this concern isn’t to be pessimistic about post-treatment control, but rather to highlight that there needs to be greater clarity about what the term means in relation to clinical outcomes.  In particular, post-treatment control should not be considered synonymous with “remission” or “functional cure;” these designations should refer to a state of health that is at least comparable to, if not superior to, that obtained by ART. At the current time, how the long-term health of post-treatment controllers compares to individuals whose viral loads are suppressed by ART is not known.

The VISCONTI researchers do attempt to highlight this uncertainty by stating that cohort participants are examples of "long-term virological remission" (emphasis added); however, as the Conway and Perelson paper shows, this distinction is not always appreciated by other scientists and is certainly lost in much of the media coverage (the BBC headline on the VISCONTI cohort was: "Early HIV drugs 'functionally cure about one in 10'"). 

There are reasons for optimism: anecdotally, the health of VISCONTI cohort members has been described to be good, and it is possible that they will not face the long-term risks seen in some elite controllers. Additionally, reports indicate there is a subset of elite controllers with extremely low HIV DNA levels from whom infectious HIV cannot be recovered, and gene expression analyses suggest these individuals have similar profiles to HIV-negative individuals (see abstract below from the recent Keystone Symposia on HIV cure research; several similar cases were reported in 2012 by the research group of Stephen Migueles at NIAID).  While further studies are needed, this subset of elite controllers might turn out to represent a model of strict HIV control that lacks inflammatory and health consequences, thereby offering clues as to the degree of post-treatment control that equates to clinical remission.

Antivir Ther. 2015 Apr 23. doi: 10.3851/IMP2963. [Epub ahead of print]

How often does treatment of primary HIV lead to post-treatment control?

Maenza J1, Tapia K, Holte S, Stekler JD, Stevens CE, Mullins JI, Collier AC.

Abstract

BACKGROUND: Post-treatment control of viremia after discontinuation of antiretroviral therapy begun during primary HIV-1 infection is considered a potential path toward a sustained remission of infection.

METHODS: Subjects enrolled in an observational primary infection cohort who received at least 11 months of highly active antiretroviral therapy beginning within the first 12 weeks of HIV-1 infection and who subsequently discontinued therapy were evaluated for post-treatment control.

RESULTS: Within a cohort of 389 subjects with primary HIV-1 infection enrolled over 22 years, only 22 met criteria for evaluation of post-treatment control. Among these subjects, twenty-one (95%) had loss of viral control (HIV-1 RNA> 500 copies/mL) within 18 months after treatment discontinuation, and only 1 (4.5%, 95% CI (0.32%, 18.9%)) controlled viral load to levels <500 copies/mL for at least 24 months. The median time to virologic failure was 2.17 (IQR 1.18 - 3.39) months.

CONCLUSIONS: Our data suggest a low likelihood of post-treatment control even when highly active antiretroviral therapy is started within 12 weeks of HIV-1 infection.

J Antimicrob Chemother. 2015 Apr 21. pii: dkv084. [Epub ahead of print]

Combined ART started during acute HIV infection protects central memory CD4+ T cells and can induce remission.

Chéret A, Bacchus-Souffan C, Avettand-Fenoël V, Mélard A, Nembot G, Blanc C, Samri A, Sáez-Cirión A, Hocqueloux L, Lascoux-Combe C, Allavena C, Goujard C, Valantin MA, Leplatois A, Meyer L, Rouzioux C, Autran B; OPTIPRIM ANRS-147 Study Group.

Abstract

BACKGROUND: Therapeutic control of HIV replication reduces the size of the viral reservoir, particularly among central memory CD4+ T cells, and this effect might be accentuated by early treatment.

METHODS: We examined the effect of ART initiated at the time of the primary HIV infection (early ART), lasting 2 and 6 years in 11 and 10 patients, respectively, on the HIV reservoir in peripheral resting CD4+ T cells, sorted into naive (TN), central memory (TCM), transitional memory (TTM) and effector memory (TEM) cells, by comparison with 11 post-treatment controllers (PTCs).

RESULTS: Between baseline and 2 years, CD4+ T cell subset numbers increased markedly (P < 0.004) and HIV DNA levels decreased in all subsets (P < 0.009). TTM cells represented the majority of reservoir cells at both timepoints, T cell activation status normalized and viral diversity remained stable over time. The HIV reservoir was smaller after 6 years of early ART than after 2 years (P < 0.019), and did not differ between PTCs and patients treated for 6 years. One patient, who had low reservoir levels in all T cell subsets after 2 years of treatment similar to the levels in PTCs, spontaneously controlled viral replication during 18 months off treatment.

CONCLUSIONS: Early prolonged ART thus limits the size of the HIV reservoir, protects long-lived cells from persistent infection and may enhance post-treatment control.

Proc Natl Acad Sci U S A. 2015 Apr 28;112(17):5467-72. doi: 10.1073/pnas.1419162112. Epub 2015 Apr 13.

Post-treatment control of HIV infection.

Conway JM, Perelson AS.

Abstract

Antiretroviral therapy (ART) for HIV is not a cure. However, recent studies suggest that ART, initiated early during primary infection, may induce post-treatment control (PTC) of HIV infection with HIV RNA maintained at <50 copies per mL. We investigate the hypothesis that ART initiated early during primary infection permits PTC by limiting the size of the latent reservoir, which, if small enough at treatment termination, may allow the adaptive immune response to prevent viral rebound (VR) and control infection. We use a mathematical model of within host HIV dynamics to capture interactions among target cells, productively infected cells, latently infected cells, virus, and cytotoxic T lymphocytes (CTLs). Analysis of our model reveals a range in CTL response strengths where a patient may show either VR or PTC, depending on the size of the latent reservoir at treatment termination. Below this range, patients will always rebound, whereas above this range, patients are predicted to behave like elite controllers. Using data on latent reservoir sizes in patients treated during primary infection, we also predict population-level VR times for noncontrollers consistent with observations.

Keystone Symposia: Mechanisms of HIV Persistence: Implications for a Cure (E1), Abstract #2012

A subset of HIV elite controllers lacking evidence of ongoing viral replication

Katja Kleinsteuber1,2, Nzuekoh Nchinda1,2, Selena Vigano1, Maria J. Buzon1, Megan E. Curtis1, Anne-Sophie Dugast1, Christine D. Palmer1, R. Brad Jones1, Sean Harrington1, Marisol Romero-Tejeda1, Alicja Piechocka-Trocha1,2, Mathias Lichterfeld1 and Bruce D. Walker1,2

1Ragon Institute of MGH, MIT and Harvard, USA; 2 Howard Hughes Medical Institute (HHMI), USA

Elite controllers are individuals who control HIV infection in the absence of therapy. However, most of these individuals still show signs of ongoing viral replication, such as generalized immune activation, intermittent blips in viral load, persistent antibody responses, effector memory T cell responses, and some experience progressive CD4 T cell decline. Here, we identify a subgroup of stable elite controllers characterized by an incomplete Western blot for virus-specific antibodies and the absence of viral blips. Plasma of these individuals mediated diminished HIV-specific antibody-dependent cell-mediated cytotoxicity (ADCC) as compared to other elite controllers, providing additional evidence of decreased antibody levels. We also detected diminished effector and increased central memory HIV-specific CD8 T-cell populations by tetramer staining, as well as decreased HIV-specific responses by intracellular cytokine staining. Analysis of the HIV reservoir showed low but detectable HIV genome in CD4 T cells from those patients. In line with these results, previously performed principal component analysis of transcriptional data from two of these patients revealed grouping with uninfected persons rather than with other elite controllers. Moreover, preliminary studies have failed to recover infectious virus thus far. Together these results suggest sustained absence of replicating virus in a subset of elite controllers, with implications for functional cure studies.