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AIDSinfo Drug Database

AIDSinfo Drug Database

Drugs by class



Tucaresol  Audio icon

Other Names: 589C80
Drug Class: Immune Modulators
Molecular Formula: C15 H12 O5
Registry Number: 84290-27-7 (CAS)
Chemical Name: 4-[(2-formyl-3-hydroxy-phenoxy)methyl]benzoic acid
Chemical Class: Benzoic Acids
Company: GlaxoSmithKline
Phase of Development: Phase II
Chemical Image:
Click image to enlarge
Molecular Weight: 272.2548

(Compound details obtained from ChemIDplus Advanced1 and NIAID Therapeutics Database2)

What is an investigational drug?

An investigational drug is one that is under study and is not approved by the U.S. Food and Drug Administration (FDA) for sale in the United States. Medical research studies are conducted to evaluate the safety and effectiveness of an investigational drug. These research studies are also called clinical trials. Once an investigational drug has been proven safe and effective in clinical trials, FDA may approve the drug for sale in the United States.

What is tucaresol?

Tucaresol is an investigational drug that is categorized as an immune modulator.2 Immune modulators (also called immunomodulators) are substances that help to activate, boost, or restore normal immune function. Tucaresol is being studied for its ability to help restore or boost the immune systems of HIV-infected individuals. The drug may help to repair damage that HIV has done to the immune system and protect the long-term health of HIV-infected individuals.3-6

How are clinical trials of investigational drugs conducted?

Clinical trials are conducted in phases. Each phase has a different purpose and helps researchers answer different questions.7

  • Phase I trials: Researchers test an investigational drug in a small group of people (20–80) for the first time. The purpose is to evaluate its safety and identify side effects.
  • Phase II trials: The investigational drug is administered to a larger group of people (100–300) to determine its effectiveness and to further evaluate its safety.
  • Phase III trials: The investigational drug is administered to large groups of people (1,000–3,000) to confirm its effectiveness, monitor side effects, compare it with standard or equivalent treatments, and collect information that will allow the investigational drug to be used safely.7

In most cases, an investigational drug must be proven safe and effective in a Phase III clinical trial to be considered for approval by FDA for sale in the United States. Some drugs go through FDA’s accelerated approval process and are approved before a Phase III clinical trial is complete. After a drug is approved by FDA and made available to the public, researchers track its safety in Phase IV trials to seek more information about the drug’s risks, benefits, and optimal use.7

In what phase of testing is tucaresol?

Tucaresol is being studied in Phase II clinical trials.2

What are some studies on tucaresol?

A Phase I/II study compared the immune modulating effects of tucaresol in four groups of HIV-infected participants. 

  • Participants in two of the groups had taken antiretroviral therapy (ART) before entering the study (treatment-experienced patients). During the study, these participants continued on their ART regimens while also taking tucaresol. 
  • Participants in the third group had never taken ART before entering the study (treatment-naive patients), but they started ART plus tucaresol once the study began. 
  • Participants in the fourth group were also treatment-naive, but they did not start ART and took only tucaresol throughout the study.3,8,9 

The groups also differed according to the participants’ CD4 count and viral load levels. (Viral load is a measure of the amount of HIV in the blood. CD4 count is a measure of the number of CD4 cells in the blood, which shows how well the immune system is working.) Changes in participants’ CD4 counts and viral loads during the study were analyzed to determine the effectiveness of tucaresol.3,8,9

Participants took increasing doses of tucaresol for 12 weeks. They took the medicine one time during week 1 of the study, and then once daily for 4 days at weeks 4, 8, and 12. Participants were then followed for at least 40 weeks so that the long-term effects of tucaresol could be determined.3,8,9

In this study, tucaresol showed immune modulating effects. These effects were greatest in the participants who were taking ART (as well as tucaresol), and who had an undetectable level of HIV in their blood (called viral suppression). The immune modulating effects included an increase in the number and activity of certain cells of the immune system. Whether the immune modulating effects of tucaresol will have any clear health benefits for HIV-infected individuals is not known, and more clinical trials are needed to determine this.3,8,9 

In terms of safety, serious side effects occurred in the first week of the study in two participants, both of whom were treatment-naive before entering the study. (One participant was taking only tucaresol and not on ART during the study; the other participant started ART for the first time along with tucaresol.) No serious side effects occurred in the treatment-experienced participants taking both ART and tucaresol throughout the study.3

What side effects might tucaresol cause?

In the Phase I/II study discussed under the previous question, the most common side effects that occurred in the treatment-experienced participants who were taking ART and tucaresol were low-grade fever and other mild constitutional symptoms. (Constitutional symptoms are symptoms affecting the whole body, such as fever and weight loss.)3

Information on possible side effects of the drug is not complete. If testing of tucaresol continues, additional information on possible side effects will be gathered.

Where can I get more information about clinical trials studying tucaresol?

More information about tucaresol-related research studies is available from the AIDSinfo database of study summaries. Click on the title of any trial in the list to see the trial summary and more information about the study.

I am interested in participating in a clinical trial of tucaresol. How can I find more information about participating in a clinical trial?

Participating in a clinical trial can provide benefits. For example, a volunteer participant can benefit from new research treatments before they are widely available. Participants also receive regular and careful medical attention from a research team that includes doctors and other health professionals. However, clinical trials may also involve risks of varying degrees, such as unpleasant, serious, or even life-threatening side effects from the treatment being studied.7

Your health care provider can help you decide whether participating in a clinical trial is right for you. For more information, visit NIH Clinical Research Trials and You.


1. United States National Library of Medicine. ChemIDplus Advanced. Last accessed on April 23, 2014.

2. National Institute of Allergy and Infectious Diseases (NIAID). NIAID ChemDB, HIV Drugs in Development. Last accessed on April 23, 2014.

3. Gori A, Trabattoni D, Bandera A, et al. Immunomodulation induced by tucaresol in HIV infection: results of a 16 week pilot Phase I/II trial. Antivir Ther. 2004 Aug;9(4):603-14. Last accessed on April 23, 2014.

4. Corbeau P, Reynes J. Immune reconstitution under antiretroviral therapy: the new challenge in HIV-1 infection. Blood. 2011 May 26;117(21):5582-90. Last accessed on April 23, 2014.

5. Lévy Y. Immunotherapy in HIV infection; current and future challenges. Retrovirology. 2010; 7(Suppl 1): I13. Last accessed on April 23, 2014.

6. Napolitano LA. Approaches to immune reconstitution in HIV infection. Top HIV Med. 2003 Sep-Oct;11(5):160-3. Last accessed on April 23, 2014.

7. National Institutes of Health (NIH). NIH Clinical Research Trials and You. Last accessed on April 23, 2014.

8. Bandera A, Gori A, Trabattoni D, et al. Positive Immunomodulatory Effects of Tucaresol in HIV-infected Patients: Results from a Phase I/II Trial after 40 Weeks of Follow-up. Abstract presented at: 10th Conference on Retroviruses and Opportunistic Infections (CROI); February 10-14, 2003; Boston, MA. Abstract 654. Last accessed on April 23, 2014.

9. Gazzola L, Marchetti G, Bandera A, et al. Dynamics of T Cells Homeostasis Induced by Tucaresol. Abstract presented at: 11th Conference on Retroviruses and Opportunistic Infections (CROI); February 8-11, 2004; San Francisco, CA. Abstract 523. Last accessed on April 23, 2014.

Last Reviewed: April 23, 2014

Last Updated: January 21, 2015

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