Development of Hexadecyloxypropyl Tenofovir (CMX157) for Treatment of Infection Caused by Wild-Type and Nucleoside/Nucleotide-Resistant HIV

Abstract

CMX157 is a lipid (1-0-hexadecyloxypropyl) conjugate of the acyclic nucleotide analog tenofovir (TFV) with activity against both wild-type and antiretroviral drug-resistant HIV strains, including multidrug nucleoside/ nucleotide analog-resistant viruses. CMX157 was consistently >300-fold more active than tenofovir against multiple viruses in several different cell systems. CMX157 was active against all major subtypes of HIV-1 and HIV-2 in fresh human peripheral blood mononuclear cells (PBMCs) and against all HIV-1 strains evaluated in monocyte-derived macrophages, with 50% effective concentrations (EC 50 s) ranging between 0.20 and 7.2 nM. The lower CMX157 EC 50 s can be attributed to better cellular uptake of CMX157, resulting in higher intracellular levels of the active antiviral anabolite, TFV-diphosphate (TFV-PP), inside target cells. CMX157 produced >30-fold higher levels of TFV-PP in human PBMCs exposed to physiologically relevant concentrations of the compounds than did TFV. Unlike conventional prodrugs, including TFV disoproxil fumarate (Viread), CMX157 remains intact in plasma, facilitating uptake by target cells and decreasing relative systemic exposure to TFV. There was no detectable antagonism with CMX157 in combination with any marketed antiretroviral drug, and it possessed an excellent in vitro cytotoxicity profile. CMX157 is a promising clinical candidate to treat wild-type and antiretroviral drug-resistant HIV, including strains that fail to respond to all currently available nucleoside/nucleotide reverse transcriptase inhibitors.

Antiviral Drug Resistance and the Need for Development of New HIV-1 Reverse Transcriptase Inhibitors

“…In contrast, TFV has EC 50 s against HIV-1 groups M and O that range between 500 and 2,200 nM in peripheral blood mononuclear cells (PBMCs) (24). In an in vitro study, CMX157 demonstrated potent activity against NRTIresistant strains, including multidrug-resistant viruses, against which it showed Ͼ300-fold the activity of TFV (38). The higher potency and lower EC 50 of CMX157 are due to better cellular uptake than that for TFV and the fact that it is not a substrate for organic anion transporters.…”

“…CMX157 (Fig. 1) is a lipid moiety prodrug of TFV that has activity against wt viruses of major HIV-1 subtypes, with EC 50 s ranging from 0.2 to 7.2 nM (38). In contrast, TFV has EC 50 s against HIV-1 groups M and O that range between 500 and 2,200 nM in peripheral blood mononuclear cells (PBMCs) (24).…”

“…4=-Ethynyl-2-fluoro-2=-dATP (EF-dATP) ( Fig. 1) is a new NRTI, now in preclinical development, that retains the 3= OH group and has excellent antiviral properties, i.e., 50% effective concentration (EC 50 ) of 0.07 nM against wt virus (31,35), compared to approved NRTIs that range in EC 50 between 17 and 89 nM (38). This robust antiviral activity is due to a mechanism of action that is different from those of approved NRTIs.…”

Inhibiting Early-Stage Events in HIV-1 Replication by Small-Molecule Targeting of the HIV-1 Capsid

“…Assays involving HIV-1 infection of human peripheral blood mononuclear cells (PBMCs) were performed as described previously (19,34). Fresh PBMCs, seronegative for HIV-1 and hepatitis B virus, were isolated from blood samples of the screened donors (Biological Specialty Corp., Colmar, PA) by using lymphocyte separation medium (density, 1.078 Ϯ 0.002 g/ml; Cellgro; Mediatech, Manassas, VA) and following the manufacturer's instructions.…”

Evaluation of PD 404,182 as an Anti-HIV and Anti-Herpes Simplex Virus Microbicide

“…Testing of the efficacy of PD against HIV-1 in PBMCs (Biological Specialty Corporation, Colmar, PA) was performed at the Southern Research Institute as described previously (24,25). Briefly, phytohemagglutinin-stimulated cells from at least two healthy donors were mixed together, diluted in fresh medium to a final concentration of 1 ϫ 10 6 cells/ml, and plated in a 96-well round-bottom microplate at 50 l/well (5 ϫ 10 4 cells/well).…”