BMS-200475 is a novel carbocyclic 2'-deoxyguanosine analog found to possess potent and selective anti-hepatitis B virus (anti-HBV) activity. BMS-200475 is distinguished from guanosine by replacement of the natural furanose oxygen on the sugar moiety with an exo carbon-carbon double bond. In the HepG2 stably transfected cell line 2.2.15, BMS-200475 had a 50% effective concentration (EC50) of 3.75 nM against HBV, as determined by analysis of secreted HBV DNA. Structurally related compounds with adenine, iodouracil, or thymine base substitutions were significantly less potent or were inactive. Direct comparison of the antiviral activities of BMS-200475 with those of a variety of other nucleoside analogs, including lamivudine (EC50 = 116.26 nM), demonstrated the clearly superior in vitro potency of BMS-200475 in 2.2.15 cells. Intracellular HBV replicative intermediates were uniformly reduced when cells were treated with BMS-200475, but rebounded after treatment was terminated. The concentration of BMS-200475 causing 50% cytotoxicity in 2.2.15 cell cultures was 30 microM, approximately 8,000-fold greater than the concentration required to inhibit HBV replication in the same cell line. Treatment with BMS-200475 resulted in no apparent inhibitory effects on mitochondrial DNA content.

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BMS-200475 was recently shown to have potent antiviral activity against hepatitis B virus (50% effective concentration ‫؍‬ 3.7 nM; 50% cytotoxic concentration ‫؍‬ 30 M). In metabolic studies in both HepG2 and hepatitis B virus-transfected 2.2.15 human hepatoma cell lines, the metabolism was similar, the primary products being the di-and triphosphates. The accumulation of triphosphate was rapid and detectable down to a 5 nM concentration of added drug. When cells were labeled at 25 M, the intracellular triphosphate concentration attained 30 pmol/10 6 cells (ϳ30 M). The intracellular half-life of the triphosphate was about 15 h. Compared with five other nucleoside analogs of medical interest (lamivudine, penciclovir, ganciclovir, acyclovir, and lobucavir), BMS-200475 was most efficiently phosphorylated to the triphosphate in HepG2 cells.

Daily oral treatment with the cyclopentyl 2′-deoxyguanosine nucleoside BMS-200475 at doses ranging from 0.02 to 0.5 mg/kg of body weight for 1 to 3 months effectively reduced the level of woodchuck hepatitis virus (WHV) viremia in chronically infected woodchucks as measured by reductions in serum WHV DNA levels and endogenous hepadnaviral polymerase activity. Within 4 weeks of daily therapy with 0.5 or 0.1 mg of BMS-200475 per kg, endogenous viral polymerase levels in serum were reduced about 1,000-fold compared to pretreatment levels. Serum WHV DNA levels determined by a dot blot hybridization technique were comparably decreased in these treated animals. In the 3-month study, the sera of animals that had undetectable levels of WHV DNA by the dot blot technique were further analyzed by a highly sensitive semiquantitative PCR assay. The results indicate that BMS-200475 therapy reduced mean WHV titers by 107- to 108-fold, down to levels as low as 102 to 103 virions/ml of serum. Southern blot hybridization analysis of liver biopsy samples taken from animals during and after BMS-200475 treatment showed remarkable reductions in the levels of WHV DNA replicative intermediates and in the levels of covalently closed circular viral DNA. WHV viremia in BMS-200475-treated WHV carriers eventually returned to pretreatment levels after therapy was stopped. These results indicate that BMS-200475 should be evaluated in clinical trials for the therapy of chronic human hepatitis B virus infections.

An asymmetric 10-step synthesis is developed affording the title compound (XII) in 18% overall yield. The use of commercial sodium cyclopentadienide (I) improves the yield of (III) 3-fold. The enantiomer of (XII) and the adenine analogue are prepared in the same manner, whereas the thymine and iodouracil analogues are prepared prior to the development of the optimized oxidation/methylenation sequence ((VII) → (X)). The novel compound (XII) is a potent inhibitor of hepatitis B virus with relatively low cytotoxicity. -(BISACCHI, G. S.; CHAO, S. T.; BACHARD, C.; DARIS, J. P.; INNAIMO, S.; JACOBS, G. A.; KOCY, O.; LAPOINTE, P.; MARTEL, A.; MERCHANT, Z.; SLUSARCHYK, W. A.; SUNDEEN, J. E.; YOUNG, M. G.; COLONNO, R.; ZAHLER, R.; Bioorg. Med. Chem. Lett. 7 (1997) 2, 127-132; Bristol-Myers Squibb Pharm. Res. Inst., Princeton, NJ 08543, USA; EN)