Phosphoramidate Prodrugs of 2′-C-Methylcytidine for Therapy of Hepatitis C Virus Infection

Abstract

The application of a phosphoramidate prodrug approach to 2'-C-methylcytidine (NM107), the first nucleoside inhibitor of the hepatitis C virus (HCV) NS5B polymerase, is reported. 2'-C-Methylcytidine, as its valyl ester prodrug (NM283), was efficacious in reducing the viral load in patients infected with HCV. Several of the phosphoramidates prepared demonstrated a 10- to 200-fold superior potency with respect to the parent nucleoside in the cell-based replicon assay. This is due to higher levels of 2'-C-methylcytidine triphosphate in the cells. These prodrugs are efficiently activated and converted to the triphosphate in hepatocytes of several species. Our SAR studies ultimately led to compounds that gave high levels of NTP in hamster and rat liver after subcutaneous dosing and that were devoid of the toxic phenol moiety usually found in ProTides.

In Vitro Phenotypic Characterization of Hepatitis C Virus NS3 Protease Variants Observed in Clinical Studies of Telaprevir

“…The susceptibility of telaprevir-resistant variants to IFN-␣, ribavirin, nucleoside NS5B polymerase inhibitors (mericitabine [37] and NM-107 [30]), and non-nucleoside NS5B polymerase inhibitors (VX-222 [31] binding to the thumb domain, HCV-796 [32] and CMPD 2 [33] binding to the palm domain, and CMPD 55 [34] binding to the finger-loop domain) was evaluated in the G1b 48-h replicon assay ( Table 4). The EC 50 s of IFN-␣ and ribavirin for replicon cells containing either single variant V36A/M, T54A, or R155K/M/T or double variant V36A/MϩR155K/T were comparable to that for WT cells (fold change ranging from 0.3 to 1.3).…”

“…Linear ketoamide NS3 protease inhibitors telaprevir (8-10) and boceprevir (26), macrocyclic NS3 protease inhibitors ciluprevir (27,28) and danoprevir (29), nucleoside NS5B polymerase inhibitor NM-107 (30), and nonnucleoside NS5B polymerase inhibitors VX-222 (31), HCV-796 (32), compound 2 (CMPD 2 [33]), and compound 55 (CMPD 55 [34]) were synthesized at Vertex Pharmaceuticals Incorporated (Cambridge, MA). Macrocyclic NS3 protease inhibitors simeprevir (35) and vaniprevir (36) were obtained from Acme Bioscience Inc. (Palo Alto, CA).…”

INX-08189, a Phosphoramidate Prodrug of 6- O -Methyl-2′- C -Methyl Guanosine, Is a Potent Inhibitor of Hepatitis C Virus Replication with Excellent Pharmacokinetic and Pharmacodynamic Properties

“…This approach facilitates the direct delivery of the monophosphorylated nucleoside analogue into the cell, bypassing the first rate-limiting phosphorylation step (4). The phosphoramidate prodrug strategy has been used successfully to improve the HCV antiviral potency of several modified nucleosides (14,19,25,27). In the case of 2Ј-C-MeG, a striking improvement in cell-based potency over that of the parent nucleoside can be achieved (Ͼ80 fold) with phosphoramidates incorporating 1-naphthyl as the aryl-leaving group (27).…”

Diastereoselective Synthesis of (Aryloxy)phosphoramidate Prodrugs

“…The antiviral evaluation of the diastereomers proved that the more lipophilic diastereomer was about 8-fold more active against HCV than the second diastereomer. [9] These examples clearly demonstrate the importance of the phosphorus configuration on the biological activity.…”