Author Interviews, HIV, Immunotherapy, PLoS / 04.12.2015
How Does PD-L1 Blockade Impact HIV Immune Response?
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Dr. Meyerhans[/caption]
MedicalResearch.com Interview with:
Andreas Meyerhans, PhD
ICREA Research Professor at the University Pompeu Fabra
Infection Biology Group
Department of Experimental and Health Sciences
Universitat Pompeu Fabra
Barcelona Spain
Medical Research: What is the background for this study? What are the main findings?
Dr. Meyerhans: In brief, chronic HIV infections lead to a dampening of HIV-specific killer cells. This phenomenon is named exhaustion and is mediated by inhibitory proteins, such as PD-1, on the cell surface. A consequence of exhaustion is a reduction of the immune control over virus expansion.
We have studied the effect of blocking the negative signaling from the inhibitory proteins by means of PD-1/PD-L1 pathway inhibition on effector and regulatory T cells (Treg). We found that one can augment antiviral immune control only when the virus load was well controlled in the HIV-infected individuals i.e. by antiviral drugs. In that case, PD-1/PD-L1 pathway blockage led to an expansion of anti-HIV killer cells over Treg cells. This latter are suppressive white blood cells also subject to the same inhibitory pathway regulation. In contrast, when blood cells from viremic HIV-infected individuals were analyzed, Treg cells expanded efficiently and thus reduced the effector to regulatory T cell ratio that controls HIV. Taken together, our data point to Treg cells as an important component in the outcome of PD-1/PD-L1 pathway inhibitor therapies and suggest a net gain in anti-HIV immune responses only when the HIV loads are well controlled during the administration of these novel compounds.
Dr. Meyerhans[/caption]
MedicalResearch.com Interview with:
Andreas Meyerhans, PhD
ICREA Research Professor at the University Pompeu Fabra
Infection Biology Group
Department of Experimental and Health Sciences
Universitat Pompeu Fabra
Barcelona Spain
Medical Research: What is the background for this study? What are the main findings?
Dr. Meyerhans: In brief, chronic HIV infections lead to a dampening of HIV-specific killer cells. This phenomenon is named exhaustion and is mediated by inhibitory proteins, such as PD-1, on the cell surface. A consequence of exhaustion is a reduction of the immune control over virus expansion.
We have studied the effect of blocking the negative signaling from the inhibitory proteins by means of PD-1/PD-L1 pathway inhibition on effector and regulatory T cells (Treg). We found that one can augment antiviral immune control only when the virus load was well controlled in the HIV-infected individuals i.e. by antiviral drugs. In that case, PD-1/PD-L1 pathway blockage led to an expansion of anti-HIV killer cells over Treg cells. This latter are suppressive white blood cells also subject to the same inhibitory pathway regulation. In contrast, when blood cells from viremic HIV-infected individuals were analyzed, Treg cells expanded efficiently and thus reduced the effector to regulatory T cell ratio that controls HIV. Taken together, our data point to Treg cells as an important component in the outcome of PD-1/PD-L1 pathway inhibitor therapies and suggest a net gain in anti-HIV immune responses only when the HIV loads are well controlled during the administration of these novel compounds.
Dr. Andrew Auld[/caption]
MedicalResearch.com Interview with:
Dr. Andrew Auld MD, MSc
Prof. Molina[/caption]
MedicalResearch.com Interview with:
Dr Jean-Michel Molina
Department of Infectious Diseases
Saint-Louis Hospital and University of Paris Diderot
Paris France
MedicalResearch: What is the background for this study? What are the main findings?
Dr. Molina: Men who have sex with men (MSM) are disproportionately affected by HIV worldwide and represent the today in Europe the largest group in which new HIV infections are diagnosed with no decrease over the last 8 years.
The first study assessing preexposure prophylaxis (PrEP) efficacy among MSM was published in 2010 (the Iprex study) which reported for the first time a 44% reduced incidence of HIV in those randomized to receive daily tenofovir/emtricitabine TDF/FTC (one pill per day) as compared to placebo. Adherence to a daily pill regimen was found to be challenging however since only half of the participants (according to drug detection in blood) were taking their daily regimen. Post-hoc analyses suggested that among those with drugs detectable in plasma, PrEP efficacy could be as high as 92%. However, long term adherence to a daily regimen represents the Achille’s heel of daily PrEP, as shown later in other large PrEP trials among women in Africa (VOICE and Fem-PrEP).
Based on data from animal models we wished to assess whether PrEP with TDF/FTC taken on demand, at the time of sexual activity, could improve adherence, thereby efficacy and also improve safety and cost.
In this randomized double blind placebo controlled trial, on demand PrEP with TDF/FTC reduced the incidence of HIV by 86% in the intent to treat analysis as compared to placebo, and the only 2 participants who became infected in the TDF/FTC arm after more than a year of follow-up, had discontinued the use of PrEP months before infection.
The ANRS Ipergay study reports therefore a very high efficacy of PrEP, similar to that also reported in another PrEP study carried out in the UK among MSM with daily TDF/FTC (PROUD), which results were disclosed at the same time. Both studies have increased awareness about the real potential of PrEP and have had a strong impact on WHO and European guidelines.














