Peldesine

IC50: 36 nM (Human RBC PNP), 5 nM (Rat RBC PNP), 32 nM (Mouse RBC PNP), and 800 nM (Human T-cell proliferation)
Ki: 23 nM (Human RBC PNP)
HIV

Peldesine (BCX 34; 0-50 µM; 72 hours; Jurkat cells) could inhibit the T-cell proliferation completely at a concentration of less than 10 μM, in the presence of dGuo (10 μM). In contrast, the B-cell proliferation is not affected by Peldesine.
Peldesine (BCX 34) suppresses T-cell immune reaction in an IL-2-independent manner, and this means that Peldesine might affect a late phase rather than an early stage in T-cell activation.
Peldesine also, in the presence but not in the absence of deoxyguanosine, inhibits human leukemia CCRF-CEM T-cell proliferation with an IC ₅₀ of 0.57 μM but not rat or mouse T-cell proliferation up to 30 μM.

Oral bioavailability of Peldesine in rats is 76%. Peldesine is orally active in elevating plasma inosine in rats (2-fold at 30 mg/kg), in suppressing ex vivo RBC PNP activity in rats (98% at 3 h. 100 mg/kg), and in suppressing ex vivo skin PNP in mice (39% at 3 h, 100 mg/kg).