Development of CMX001 for the Treatment of Poxvirus Infections

CMX001 (phosphonic acid, [[(S)-2-(4-amino-2-oxo-1(2H)-pyrimidinyl)-1-(hydroxymethyl)ethoxy]methyl]mono[3-(hexadecyloxy)propyl] ester) is a lipid conjugate of the acyclic nucleotide phosphonate, cidofovir (CDV). CMX001 is currently in Phase II clinical trials for the prophylaxis of human cytomegalovirus infection and under development using the Animal Rule for smallpox infection. It has proven effective in reduction of morbidity and mortality in animal models of human smallpox, even after the onset of lesions and other clinical signs of disease. CMX001 and CDV are active against all five families of double-stranded DNA (dsDNA) viruses that cause human morbidity and mortality, including orthopoxviruses such as variola virus, the cause of human smallpox. However, the clinical utility of CDV is limited by the requirement for intravenous dosing and a high incidence of acute kidney toxicity. The risk of nephrotoxicity necessitates pre-hydration and probenecid administration in a health care facility, further complicating high volume CDV use in an emergency situation. Compared with CDV, CMX001 has a number of advantages for treatment of smallpox in an emergency including greater potency in vitro against all dsDNA viruses that cause human disease, a high genetic barrier to resistance, convenient oral administration as a tablet or liquid, and no evidence to date of nephrotoxicity in either animals or humans. The apparent lack of nephrotoxicity observed with CMX001 in vivo is because it is not a substrate for the human organic anion transporters that actively secrete CDV into kidney cells. The ability to test the safety and efficacy of CMX001 in patients with life-threatening dsDNA virus infections which share many basic traits with variola is a major advantage in the development of this antiviral for a smallpox indication

STUDIES ON THE HYDROLYSIS AND PHARMACOLOGICAL UTILITY OF GEMINAL AMINOAMIDES

Geminal aminoamides are of interest since they have been used as amino termini in retro-inverso peptides, peptide protecting groups, intermediates in carboxyl-terminal peptide degradations, -amino-alkyl cation synthons and as prodrugs. The mechanism of hydrolysis of N-(1-aminoalkyl) amides has been studied. A pH rate-profile was obtained for the hydrolysis of N-(1-aminoisobutyl)-2-methoxyacetamide hydrochloride. Plateaus were observed both in the acidic and basic regions, while the rate of hydrolysis was faster in the basic region. The compounds hydrolyze to amides, aldehydes and ammonia. An iminium ion has been trapped in the basic pH region by cyanide proving it is an intermediate in hydrolysis. It has also been demonstrated that the hydrolysis of N-(1-aminoalkyl) amides is very sensitive to amide leaving group effects. Having demonstrated that an iminium ion is an intermediate product in the hydrolysis of N-(1-aminoalkyl)amides, further investigations were carried out to determine whether these compounds could act as serine protease suicide inhibitors. To date, no group has investigated whether geminal aminoamides can act as suicide inhibitors of acetylcholinesterase. Compounds were synthesized which were (1) geminal aminoamides , (2) positively charged, and (3) carbamates. It has been demonstrated that (methoxycarbonyl)-amino methylamine hydrochloride is a competitive inhibitor of acetylcholinesterase. The benzyl and naphthyl derivatives proved to inhibit acetylcholinesterase over time but activity was regenerated using hydroxylamine. A preliminary study on the hydrolysis of N-((alpha)-alkoxyalkyl)amides has been carried out. N-(1-Methoxy-2-methylpropyl)acetamide. From a plot of log k 5\u27 vs. H(,A) it was found that the hydrolysis of N-(1-methoxy-2-methylpropyl)acetamide is acid catalyzed. It has been hypothesized that N-((alpha)-alkoxyalkyl)amides might be developed as prodrugs in future research

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

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 (EC50s) ranging between 0.20 and 7.2 nM. The lower CMX157 EC50s 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

Evaluation of Hexadecyloxypropyl-9-R-[2-(Phosphonomethoxy)Propyl]- Adenine, CMX157, as a Potential Treatment for Human Immunodeficiency Virus Type 1 and Hepatitis B Virus Infections▿

9-R-[2-(Phosphonomethoxy)propyl]-adenine (tenofovir) is an acyclic nucleoside phosphonate with antiviral activity against human immunodeficiency virus type 1 (HIV-1) and hepatitis B virus (HBV). Tenofovir is not orally bioavailable but becomes orally active against HIV-1 infection as the disoproxil ester (tenofovir disoproxil fumarate [Viread]). We have developed an alternative strategy for promoting the oral availability of nucleoside phosphonate analogs which involves esterification with a lipid to form a lysolecithin mimic. This mimic can utilize natural lysolecithin uptake pathways in the gut, resulting in high oral availability. Since the mimic is not subject to cleavage in the plasma by nonspecific esterases, it remains intact in the circulation and facilitates uptake by target cells. Significant drops in apparent antiviral 50% effective concentrations (EC50s) of up to 3 logs have been observed in comparison with non-lipid-conjugated parent compounds in target cells. We have applied this technology to tenofovir with the goal of increasing oral availability, decreasing the apparent EC50, and decreasing the potential for nephrotoxicity by reducing the exposure of the kidney to the free dianionic tenofovir. Here we report that, in vitro, the hexadecyloxypropyl ester of tenofovir, CMX157, is 267-fold more active than tenofovir against HIV-1 and 4.5-fold more active against HBV. CMX157 is orally available and has no apparent toxicity when given orally to rats for 7 days at doses of 10, 30, or 100 mg/kg/day. Consequently, CMX157 represents a second-generation tenofovir analog which may have an improved clinical profile

Initiation factor modifications in the preapoptotic phase

Recent studies have identified several mechanistic links between the regulation of translation and the process of apoptosis. Rates of protein synthesis are controlled by a wide range of agents that induce cell death, and in many instances, the changes that occur to the translational machinery precede overt apoptosis and loss of cell viability. The two principal ways in which factors required for translational activity are modified prior to and during apoptosis involve (i) changes in protein phosphorylation and (ii) specific proteolytic cleavages. In this review, we summarise the principal targets for such regulation, with particular emphasis on polypeptide chain initiation factors eIF2 and eIF4G and the eIF4E-binding proteins. We indicate how the functions of these factors and of other proteins with which they interact may be altered as a result of activation of apoptosis and we discuss the potential significance of such changes for translational control and cell growth regulation