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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:
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Molecular Weight: 272.2548

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


Mechanism of Action: Immune modulator. Tucaresol, a substituted benzaldehyde, is a low-molecular-weight compound that enhances co-stimulatory signaling to CD4-positive T-cells. Immune induction is dependent on transient covalent bonding (Schiff base formation) between carbonyls and amines expressed on antigen presenting cell (APC) and T-cell surfaces. Tucaresol substitutes for the natural donor of carbonyl groups to mimic the transient bonding that is essential for T-cell activation.3-5 

In preliminary studies, tucaresol has been shown to stimulate HIV-specific cytotoxic T lymphocyte responses and generation of naive T cells via thymopoiesis in patients receiving antiretroviral therapy (ART) who have suppressed viremia. Tucaresol appears to specifically increase type 1 cytokine production. The clinical benefits of tucaresol use as an adjuvant agent to enhance immune response and restoration in patients receiving ART are still unknown.6-8

: The tucaresol terminal elimination half-life ranged from 105 to 113 hours in a 200-mg single-dose study in healthy men and women who were not HIV-infected. (The investigational drug was administered on two separate occasions, under fed and fasted states).9

Resistance: In an analysis of HIV-1 envelope V3 sequences in viral specimens obtained from tucaresol-treated patients in a Phase I/II trial at study entrance and at week 16, tucaresol administration was found to not accelerate V3 evolution.10 

Dosing in Clinical Trials

Tucaresol is administered orally.6-8

Phase I/II (HIV-infected treatment-naive and treatment–experienced participants at varying levels of viremia and immunocompetence):

  • Pilot study to determine the safety and immunomodulating effects of tucaresol.
    Tucaresol was administered according to a pulse dose escalation protocol to patients in four groups: two groups on stable ART and two ART-naive groups, one of which started ART during the study. Pulse dose escalation was initiated with tucaresol 25 mg administered as a single dose during Week 1 and gradual dose increase to tucaresol 100 mg administered once daily for 4 days during Week 12 (approximately 3-week washout between each dose level).6-8

Other clinical trials of tucaresol have also been undertaken.

Adverse Events

In the Phase I/II pulse dose escalation study of tucaresol administered over 12 weeks, two tucaresol-related serious adverse events occurred in the first week of treatment: one in a patient taking tucaresol alone and the other in a patient starting both tucaresol and ART. Both serious adverse events involved constitutional signs and symptoms, as well as a decrease in HIV RNA and CD4-positive lymphocytes. After discontinuation of the study drug and administration of either anti-inflammatories or prednisone, all tucaresol-related symptoms subsided and immunovirological abnormalities reverted to prior states.6 

No serious adverse events were reported in patients who were receiving tucaresol as an adjuvant to ongoing ART. In this group of patients, the most common adverse events were low-grade fever and mild constitutional symptoms.6

Drug Interactions

Tucaresol drug interactions are currently unknown.


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. Chen H, Rhodes J. Schiff base forming drugs: mechanisms of immune potentiation and therapeutic potential. J Mol Med (Berl). 1996 Sep;74(9):497-504. Last accessed on April 23, 2014.

4. Rhodes J. Discovery of immunopotentiatory drugs: current and future strategies. Clin Exp Immunol. 2002 Dec;130(3):363-9. Last accessed on April 23, 2014.

5. Rhodes J. Therapeutic potential of Schiff base-forming drugs. Expert Opin Investig Drugs. 1996 Mar;5(3):257-268. Last accessed on April 23, 2014.

6. 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.

7. 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.

8. 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.

9. Peck RW, Wootton R, Wiggs R, Layton G, Posner J. Effect of food and gender on the pharmacokinetics of tucaresol in healthy volunteers. Br J Clin Pharmacol. 1998 Jul;46(1):83-6. Last accessed on April 23, 2014.

10. Bulgheroni E, Bandera A, Galli M, Gori A, Rusconi S. Analysis of the env V3 sequences obtained from patients with HIV type 1 infection treated with the immune modulant agent tucaresol. AIDS Res Hum Retroviruses. 2005 Sep;21(9):815-9. Last accessed on April 23, 2014.

Last Reviewed: April 23, 2014

Last Updated: January 21, 2015

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