CS-92

Computational approaches are developed to design or rationally select, from structural databases, pyrimidyl nucleosides with anti-HIV activity. A data set of 141 nucleoside derivatives was selected from literature, and a discriminant function was derived with the use of TOPS-MODE descriptors. The model is able to classify correctly 83% of the compounds in a training set and 88.5% in a cross-validation set. The use of an external prediction set selected from the most recent literature proved that the model has good predictive ability, with a good classification of 85% of the compounds in this set. This model permitted the structural interpretation of the anti-HIV activity of these nucleoside analogues. This interpretation is formulated as several rules concerning the influence of several structural features on the activity/inactivity of such compounds. A QSAR model for the most active compounds was developed with the combined use of 2D and 3D connectivity indices. This model explains 88% of the variance in the activity of these compounds in MT4 assay. The combination of both models will permit the selection of pyrimidyl nucleoside leads and their optimization to improve the potency of the selected ones.

Triangle Pharmaceuticals is developing DAPD, a prodrug of the viral replication inhibitor dioxolane guanosine, as a potential therapy for HIV and HBV infection. Phase I/II dose range studies have commenced for HIV, and clinical development for HBV was to have commenced by late 1999 [319145], [319956]. Phase II trials are scheduled for the second quarter of 2001. The FDA has designated DAPD as a Fast Track product [365894]. DAPD is from a different nucleoside series to FTC and CS-92, which are also in development by Triangle. The compound may offer advantages over several nucleosides from other series that are already on the market because of its unique structure and pharmacological properties [247083]. Both DAPD and DXG are dioxolane purine nucleoside analogs [319660]. Preclinical data suggest DAPD may be of use in combination therapies for HIV-infected patients who are therapy-naive, in addition to patients who have previously received treatment and including those infected with drug-resistant strains of HIV-1 [341145], [341335]. Triangle licensed DAPD from Emory University [216900]. In June 1999, Triangle and Abbott Laboratories entered into an alliance for the development and marketing of six antiviral products, including DAPD [326824].