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Last updated 9/15/2022

Some individuals who initiate antiretroviral therapy (ART) experience limited recovery of CD4 T cell numbers despite suppression of HIV viral load to undetectable levels. The most common risk factors for this type of discordant response to ART are low CD4 T cell count at the time of starting and older age. Individuals in this situation still experience a benefit from ART in terms of a greatly reduced risk of opportunistic infections, illness and death, but their risk of these outcomes is higher than among people with greater CD4 T cell gains (for additional background see the webinar hosted by TAG on November 29, 2017, our March 2018 Issue Brief, and a scientific review published on February 17, 2021.)

A number of clinical trials are investigating approaches that might boost CD4 T cell recovery in individuals whose CD4 T cell counts remain relatively low despite viral load suppression. The purpose of this page is to provide a resource listing of these clinical trials, which will be updated on an ongoing basis.

Complete information on the trials is available from by clicking on the study title link.

COVID-19 Update, 8/16/21: The clinical research featured in this listing has been significantly affected by the COVID-19 pandemic. Trials that have yet to begin recruiting may be delayed, and there have been temporary suspensions of enrollment for some ongoing studies. Research is restarting as the situation improves in some areas, but study contacts listed in the individual trial registry entries should be contacted for the latest information. The International AIDS Society (IAS) has issued guidance on mitigation strategies to safely conduct HIV treatment research in the context of COVID-19.

A Safety Study of Brentuximab Vedotin in Participants With HIV
United States (no specific sites listed, contact Seagen Trial Information Support, 866-333-7436 or
CD4 cell count 51 to 200
On ART with an HIV viral load <50 copies/mL for at least 24 months

Inflammation, NK Cells, Antisense Protein and Exosomes, and Correlation with Immune Response During HIV Infection (INKASE)
Observational study (no interventions)
Age >45yrs, HIV viral load <50 copies/mL in the past 2 years
For immune non-responders: CD4 cell count < 350 on the last two tests

Changes in Immunologic Parameters Following the Addition of Fostemsavir in Virologically Suppressed Immunologic Non-responders Living With HIV – the RECOVER Study
Orlando Immunology Center
CD4 cell count<350 cells while on ART for at least 2 years, two viral load measurements <50 copies/mL within the last year prior to screening
Stable ART regimen for ≥6 months prior to screening
Stable insurance plan

Zadaxin and HIV-positive Patients With Immune Reconstitution Disorder
Fudan University, Shanghai, China
CD4 cell count >100 and <350 cells, on ART with undetectable viral load for at least 2 years

Allogeneic Adoptive Immune Therapy for Advanced AIDS Patients
Beijing 302 Hospital of China
CD4 cell count </=200 cells/uL

Probiotic Supplementation for Those Immune Non-responders With HIV-1 Infection
Peking Union Medical College Hospital, Beijing, China
ART for >2 years, CD4 cell count <350 for past 2 years, undetectable viral load for past 2 years

A Single Dose of Pembrolizumab in HIV-Infected People
National Institutes of Health Clinical Center, Bethesda, Maryland, United States
ART for >/= 12 months, CD4 cell count 100-350, viral load <40 copies/mL for >/= 12 month (single blip >40 copies/mL but <500 copies/mL allowed)

Pyridostigmine as Immunomodulator in People Living With HIV
(suspended – due to COVID-19, effective 3/19/2020 recruitment is halted until further notice)
Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán
Tlalpan, Ciudad de México, Mexico
Stable ART for at least six months, at least two undetectable viral load determinations in the previous six months.

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