16th International HIV Drug Resistance Workshop 12-16 June 2007, Barbados

NOVEL, SMALL MOLECULE INHIBITORS OF HIV-1 INTEGRASE

Antivir Ther. 2007; 12:S8 (abstract no. 6)

JJ Wu, G Milot, S Dandache, K Gouveia, Y Xiao, J Yelle, G Sevigny, A Dubois, B Tian, V Perron, D Herbart and BR Stranix
Ambrilia Biopharma Inc., Montreal, Canada

BACKGROUND: HIV-1 integrase (IN) has recently been validated clinically as an important target for the treatment of HIV/AIDS. A number of IN inhibitors are in late stages of clinical trials. We report here novel pyrazolopyridine compounds as a new class of IN inhibitors.

METHODS: The DNA competition and cross-competition kinetic studies were performed using the HIV-1 IN strand-transfer assay. The inhibitor cross-competition kinetics were based on a published method (Tian et al., J Biol Chem. 2003 Aug 1;278(31):28968-75). In the single-cycle infection assay, MT-4 cells were infected with a defective (env-), luciferase-bearing NL-4.3 virus pseudotyped with HIV-1 env (HXB-2). In the multicycle infection assay, the antiviral activity of the compounds was determined by a cytoprotection assay (MTT) using NL-4.3 in MT-4 cells. The cytotoxicity of the compounds was tested in parallel using the same assay but without adding virus to the cells.

RESULTS: Pyridoxal-5′-phosphate derivatives were initially developed as non-cytotoxic IN inhibitors with submicromolar activities against IN enzyme and wild-type HIV-1 viruses in cellular assays. The lead optimization of physiochemical properties and potency has lead to the identification of a novel pyrazolopyridine series. A number of pyrazolopyridine compounds demonstrated potent inhibition (IC₅₀=80–800 nM) of IN strand-transfer activity, but did not exhibit significant inhibition of IN 3′-processing activity. Preliminary kinetic analyses suggested that these compounds inhibited the strand transfer in a non-competitive manner with respect to the DNA substrate. Furthermore, preliminary inhibitor cross-competition studies showed that the pyrazolopyridine compounds did not compete kinetically with known competitive strand-transfer inhibitors such as diketo acid compounds, suggesting a different mechanism of action or a different binding site. Finally, a number of pyrazolopyridine compounds showed high nanomolar activity against wild-type viruses in cellular assays without cytotoxicity (IC₅₀ >100 µM).

CONCLUSIONS: A novel series of pyrazolopyridine IN inhibitors have been developed. These compounds demonstrated potent inhibition against HIV-1 IN strand-transfer activity. More importantly, pyrazolopyridine compounds showed a potentially distinct mechanism of strand-transfer inhibition, which may lead to a different resistance profile from known competitive strand-transfer inhibitors currently under clinical development.

2007-06-12
6

Copyright © 2006 - International Medical Press Ltd.. Reproduction of this abstract (other than one copy for personal reference) must be cleared through the International Medical Press Ltd. 2-4 Idol Lane, London EC3R 5DD UK.