ABSTRACT
GS-9148 [(5-(6-amino-purin-9-yl)-4-fluoro-2,5-dihydro-furan-2-yloxymethyl)phosphonic acid] 4 is a novel nucleoside phosphonate HIV-1 reverse transcriptase (RT) inhibitor with a unique resistance profile toward N(t)RTI resistance mutations. To effectively deliver 4 and its active phosphorylated metabolite 15 into target cells, a series of amidate prodrugs were designed as substrates of cathepsin A, an intracellular lysosomal carboxypeptidase highly expressed in peripheral blood mononuclear cells (PBMCs). The ethylalaninyl phosphonamidate prodrug 5 (GS-9131) demonstrated favorable cathepsin A substrate properties, in addition to favorable in vitro intestinal and hepatic stabilities. Following oral dosing (3mg/kg) in Beagle dogs, high levels (>9.0microM) of active metabolite 15 were observed in PBMCs, validating the prodrug design process and leading to the nomination of 5 as a clinical candidate.
Subject(s)
Adenine/analogs & derivatives , Anti-HIV Agents/pharmacology , Guanosine/analogs & derivatives , HIV-1/drug effects , Reverse Transcriptase Inhibitors/pharmacology , Adenine/chemical synthesis , Adenine/pharmacology , Animals , Anti-HIV Agents/chemical synthesis , Anti-HIV Agents/chemistry , CD4-Positive T-Lymphocytes/drug effects , Dogs , Drug Design , Drug Resistance, Viral/drug effects , Drug Stability , Guanosine/pharmacology , Nucleosides/pharmacology , Organophosphonates/pharmacology , Prodrugs/metabolism , Prodrugs/pharmacology , Reverse Transcriptase Inhibitors/chemical synthesis , Tumor Cells, CulturedABSTRACT
A diphosphate of a novel cyclopentyl based nucleoside phosphonate with potent inhibition of HIV reverse transcriptase (RT) (20, IC(50)=0.13 microM) has been discovered. In cell culture the parent phosphonate diacid 9 demonstrated antiviral activity EC(50)=16 microM, within two-fold of GS-9148, a prodrug of which is currently under clinical investigation, and within 5-fold of tenofovir (PMPA). In vitro cellular metabolism studies using 9 confirmed that the active diphosphate metabolite is produced albeit at a lower efficiency relative to GS-9148.
Subject(s)
Anti-HIV Agents/chemical synthesis , Anti-HIV Agents/pharmacology , Nucleosides/chemical synthesis , Organophosphonates/chemical synthesis , Reverse Transcriptase Inhibitors/chemical synthesis , Cell Line, Tumor , Drug Design , HIV Reverse Transcriptase/antagonists & inhibitors , HIV Reverse Transcriptase/chemistry , Humans , Models, Molecular , Molecular Structure , Nucleosides/chemistry , Nucleosides/pharmacology , Organophosphonates/chemistry , Organophosphonates/pharmacology , Prodrugs/chemical synthesis , Prodrugs/pharmacokinetics , Prodrugs/pharmacology , Reverse Transcriptase Inhibitors/chemistry , Reverse Transcriptase Inhibitors/therapeutic use , Structure-Activity RelationshipABSTRACT
GS-9148 (2'-Fd4AP, 4) has been identified as a nucleoside phosphonate reverse transcriptase (RT) inhibitor with activity against wild-type HIV (EC(50)=12 microM). Unlike many clinical RT inhibitors, relevant reverse transcriptase mutants (M184V, K65R, 6-TAMs) maintain a susceptibility to 2'-Fd4AP that is similar to wild-type virus. The 2'-fluorine group was rationally designed into the molecule to improve the selectivity profile and in preliminary studies using HepG2 cells, compound 4 showed no measurable effect on mitochondrial DNA content indicating a low potential for mitochondrial toxicity.
Subject(s)
Anti-HIV Agents/chemical synthesis , Anti-HIV Agents/pharmacology , Fluorine/chemistry , Guanosine/analogs & derivatives , Guanosine/chemical synthesis , Guanosine/pharmacology , Nucleosides/chemical synthesis , Nucleosides/pharmacology , Organophosphonates/chemical synthesis , Organophosphonates/pharmacology , Reverse Transcriptase Inhibitors/chemical synthesis , Reverse Transcriptase Inhibitors/pharmacology , Anti-HIV Agents/chemistry , DNA, Mitochondrial/drug effects , Guanosine/chemistry , HIV Reverse Transcriptase/genetics , Humans , Molecular Structure , Nucleosides/chemistry , Organophosphonates/chemistry , Reverse Transcriptase Inhibitors/chemistry , Structure-Activity Relationship , Zidovudine/pharmacologyABSTRACT
A series of nucleoside phosphonate reverse transcriptase (RT) inhibitors have been synthesized and their anti-HIV activity and resistance profiles evaluated. The most potent analog [5-(6-amino-purin-9-yl)-2,5-dihydro-furan-2-yloxymethyl]-phosphonic acid (d4AP) demonstrated a HIV EC(50)=2.1 microM, and the most favorable resistance profile against HIV-1 variants with K65R, M184V or multiple thymidine analog mutations in RT.
