efficacy of next-generation dihydrotriazines and biguanides against babesiosis and malaria parasites.

and pathogens, the causative agents of babesiosis and malaria, are vector-borne intraerythrocytic protozoan parasites, posing significant threats to both human and animal health. The widespread resistance exhibited by these pathogens to various classes of antiparasitic drugs underscores the need for the development of novel and more effective therapeutic strategies. Antifolates have long been recognized as attractive antiparasitic drugs as they target the folate pathway, which is essential for the biosynthesis of purines and pyrimidines, and thus is vital for the survival and proliferation of protozoan parasites.

Relevance of Higher-Order Epistasis in Drug Resistance.

We studied five chemically distinct but related 1,3,5-triazine antifolates with regard to their effects on growth of a set of mutants in dihydrofolate reductase. The mutants comprise a combinatorially complete data set of all 16 possible combinations of four amino acid replacements associated with resistance to pyrimethamine in the malaria parasite Plasmodium falciparum. Pyrimethamine was a mainstay medication for malaria for many years, and it is still in use in intermittent treatment during pregnancy or as a partner drug in artemisinin combination therapy.

Efficacy and Pharmacokinetics of the 2-Aminomethylphenol Antimalarial JPC-3210 in the Monkey-Human Malaria Model.

Nonimmune monkeys infected with and were cured of their infections when treated with a single oral dose of 5 mg/kg and 10 mg/kg of the 2-aminomethylphenol, JPC-3210, respectively. Corresponding mean blood elimination half-lives of JPC-3210 were lengthy at 19.1 days and 20.

Multi-omic Characterization of the Mode of Action of a Potent New Antimalarial Compound, JPC-3210, Against .

The increasing incidence of antimalarial drug resistance to the first-line artemisinin combination therapies underpins an urgent need for new antimalarial drugs, ideally with a novel mode of action. The recently developed 2-aminomethylphenol, JPC-3210, (MMV 892646) is an erythrocytic schizonticide with potent antimalarial activity against multidrug-resistant lines, low cytotoxicity, potent efficacy against murine malaria, and favorable preclinical pharmacokinetics including a lengthy plasma elimination half-life. To investigate the impact of JPC-3210 on biochemical pathways within infected red blood cells, we have applied a "multi-omics" workflow based on high resolution orbitrap mass spectrometry combined with biochemical approaches.

Validation of the triple timed up-and-go test in Lambert-Eaton myasthenia.

Introduction: There are no validated, practical, and quantitative measures of disease severity in Lambert-Eaton myasthenia (LEM).

Methods: Data from the Effectiveness of 3,4-Diaminopyridine in Lambert-Eaton Myasthenic Syndrome (DAPPER) trial were analyzed to assess triple timed up-and-go (3TUG) reproducibility and relationships between 3TUG times and other measures of LEM severity.

Results: The coverage probability technique showed ≥0.

Characterization of the Preclinical Pharmacology of the New 2-Aminomethylphenol, JPC-3210, for Malaria Treatment and Prevention.

The new 2-aminomethylphenol, JPC-3210, has potent antimalarial activity against multidrug-resistant lines, low cytotoxicity, and high efficacy against murine malaria. Here we report on the pharmacokinetics of JPC-3210 in mice and monkeys and the results of screening assays, including the inhibition of cytochrome P450 (CYP450) isozymes. In mice, JPC-3210 was rapidly absorbed and had an extensive tissue distribution, with a brain tissue-to-plasma concentration ratio of about 5.

3,4-diaminopyridine base effectively treats the weakness of Lambert-Eaton myasthenia.

Introduction: 3,4-diaminopyridine has been used to treat Lambert-Eaton myasthenia (LEM) for 30 years despite the lack of conclusive evidence of efficacy.

Methods: We conducted a randomized double-blind placebo-controlled withdrawal study in patients with LEM who had been on stable regimens of 3,4-diaminopyridine base (3,4-DAP) for ≥ 3 months. The primary efficacy endpoint was >30% deterioration in triple timed up-and-go (3TUG) times during tapered drug withdrawal.

Population Pharmacokinetics/Pharmacodynamics of 3,4-Diaminopyridine Free Base in Patients With Lambert-Eaton Myasthenia.

Lambert-Eaton myasthenia (LEM) is a rare autoimmune disorder associated with debilitating muscle weakness. There are limited treatment options and 3,4-diaminopyridine (3,4-DAP) free base is an investigational orphan drug used to treat LEM-related weakness. We performed a population pharmacokinetic/pharmacodynamic (PK/PD) analysis using 3,4-DAP and metabolite concentrations collected from a phase II study in patients with LEM.

Reliability of the triple-timed up-and-go test.

Introduction: We report the reliability of a new measure, the triple-timed up-and-go (3TUG) test, for assessing clinical function in patients with Lambert-Eaton myasthenia (LEM).

Methods: Intrarater reproducibility and interrater agreement of the 3TUG test were assessed in 25 control participants, 24 patients with non-LEM neuromuscular disease, and 12 patients with LEM. The coverage probability (CP) method was the primary measure of reproducibility and agreement.

Lead Selection of a New Aminomethylphenol, JPC-3210, for Malaria Treatment and Prevention.

Structure-activity relationship studies of trifluoromethyl-substituted pyridine and pyrimidine analogues of 2-aminomethylphenols (JPC-2997, JPC-3186, and JPC-3210) were conducted for preclinical development for malaria treatment and/or prevention. Of these compounds, JPC-3210 [4-(tert-butyl)-2-((tert-butylamino)methyl)-6-(5-fluoro-6-(trifluoromethyl)pyridin-3-yl)phenol] was selected as the lead compound due to superior in vitro antimalarial activity against multidrug-resistant Plasmodium falciparum lines, lower in vitro cytotoxicity in mammalian cell lines, longer plasma elimination half-life, and greater in vivo efficacy against murine malaria.

Evolution from double to triple-antimalarial drug combinations.

Drug combinations are used to treat multiple-drug resistant malaria parasites and to attempt to further delay the evolution of drug resistance. Most current antimalarial combinations are binary but it is likely that new triple drug combinations will be required in the future. A review of previous triple combinations of antimalarial drugs was done to focus attention on past problems and possible future combinations.

JPC-2997, a new aminomethylphenol with high in vitro and in vivo antimalarial activities against blood stages of Plasmodium.

4-(tert-Butyl)-2-((tert-butylamino)methyl)-6-(6-(trifluoromethyl)pyridin-3-yl)-phenol (JPC-2997) is a new aminomethylphenol compound that is highly active in vitro against the chloroquine-sensitive D6, the chloroquine-resistant W2, and the multidrug-resistant TM90-C2B Plasmodium falciparum lines, with 50% inhibitory concentrations (IC50s) ranging from 7 nM to 34 nM. JPC-2997 is >2,500 times less cytotoxic (IC50s > 35 μM) to human (HepG2 and HEK293) and rodent (BHK) cell lines than the D6 parasite line. In comparison to the chemically related WR-194,965, a drug that had advanced to clinical studies, JPC-2997 was 2-fold more active in vitro against P.

Discrimination of potent inhibitors of Toxoplasma gondii enoyl-acyl carrier protein reductase by a thermal shift assay.

Many microbial pathogens rely on a type II fatty acid synthesis (FASII) pathway that is distinct from the type I pathway found in humans. Enoyl-acyl carrier protein reductase (ENR) is an essential FASII pathway enzyme and the target of a number of antimicrobial drug discovery efforts. The biocide triclosan is established as a potent inhibitor of ENR and has been the starting point for medicinal chemistry studies.

Novel diaryl ureas with efficacy in a mouse model of malaria.

Exploration of triclosan analogs has led to novel diaryl ureas with significant potency against in vitro cultures of drug-resistant and drug-sensitive strains of the human malaria parasite Plasmodium falciparum. Compound 18 demonstrated EC(50) values of 37 and 55 nM versus in vitro cultured parasite strains and promising in vivo efficacy in a Plasmodium berghei antimalarial mouse model, with >50% survival at day 31 post-treatment when administered subcutaneously at 256 mg/kg. This series of compounds provides a chemical scaffold of novel architecture, as validated by cheminformatics analysis, to pursue antimalarial drug discovery efforts.

Triclosan derivatives: towards potent inhibitors of drug-sensitive and drug-resistant Mycobacterium tuberculosis.

Triclosan has been previously shown to inhibit InhA, an essential enoyl acyl carrier protein reductase involved in mycolic acid biosynthesis, the inhibition of which leads to the lysis of Mycobacterium tuberculosis. Using a structure-based drug design approach, a series of 5-substituted triclosan derivatives was developed. Two groups of derivatives with alkyl and aryl substituents, respectively, were identified with dramatically enhanced potency against purified InhA.

The fatty acid biosynthesis enzyme FabI plays a key role in the development of liver-stage malarial parasites.

The fatty acid synthesis type II pathway has received considerable interest as a candidate therapeutic target in Plasmodium falciparum asexual blood-stage infections. This apicoplast-resident pathway, distinct from the mammalian type I process, includes FabI. Here, we report synthetic chemistry and transfection studies concluding that Plasmodium FabI is not the target of the antimalarial activity of triclosan, an inhibitor of bacterial FabI.

Novel triazine JPC-2067-B inhibits Toxoplasma gondii in vitro and in vivo.

Background And Methodology: Toxoplasma gondii causes substantial morbidity, mortality, and costs for healthcare in the developed and developing world. Current medicines are not well tolerated and cause hypersensitivity reactions. The dihydrotriazine JPC-2067-B (4, 6-diamino-1, 2-dihydro-2, 2-dimethyl-1-(3'(2-chloro-, 4-trifluoromethoxyphenoxy)propyloxy)-1, 3, 5-triazine), which inhibits dihydrofolate reductase (DHFR), is highly effective against Plasmodium falciparum, Plasmodium vivax, and apicomplexans related to T.

Multicenter randomized, double-blind, placebo-controlled, clinical trial of dapsone as a glucocorticoid-sparing agent in maintenance-phase pemphigus vulgaris.

Objective: To determine the efficacy of dapsone as a glucocorticoid-sparing agent in maintenance-phase pemphigus vulgaris (PV).

Design: A randomized, double-blind, placebo-controlled study with a crossover arm for those who failed treatment.

Setting: A US multicenter outpatient study.

Role of specific cytochrome P450 isoforms in the conversion of phenoxypropoxybiguanide analogs in human liver microsomes to potent antimalarial dihydrotriazines.

Phenoxypropoxybiguanides, such as PS-15, are antimalarial prodrugs analogous to the relationship of proguanil and its active metabolite cycloguanil. Unlike cycloguanil, however, WR99210, the active metabolite of PS-15, has retained in vitro potency against newly emerging antifolate-resistant malaria parasites. Recently, in vitro metabolism of a new series of phenoxypropoxybiguanide analogs has examined the production of the active triazine metabolites by human liver microsomes.

Antimalarial pharmacodynamics and pharmacokinetics of a third-generation antifolate--JPC2056--in cynomolgus monkeys using an in vivo in vitro model.

Objectives: To assess the antimalarial pharmacodynamics and pharmacokinetics of the novel dihydrofolate reductase (DHFR) inhibitor, JPC2056 and its principal active metabolite JPC2067 in cynomolgus monkeys using an in vivo-in vitro model.

Methods: In a two-phase crossover design, five cynomolgus monkeys were administered a single dose (20 mg/kg) and multiple doses (20 mg/kg daily for 3 days) of JPC2056. Plasma samples collected from treated monkeys were assessed for in vitro antimalarial activity against Plasmodium falciparum lines having wild-type (D6), double-mutant (K1) and quadruple-mutant (TM90-C2A) DHFR-thymidylate synthase (TS) and a P.

X-ray structural analysis of Plasmodium falciparum enoyl acyl carrier protein reductase as a pathway toward the optimization of triclosan antimalarial efficacy.

The x-ray crystal structures of five triclosan analogs, in addition to that of the isoniazid-NAD adduct, are described in relation to their integral role in the design of potent inhibitors of the malarial enzyme Plasmodium falciparum enoyl acyl carrier protein reductase (PfENR). Many of the novel 5-substituted analogs exhibit low micromolar potency against in vitro cultures of drug-resistant and drug-sensitive strains of the P. falciparum parasite and inhibit purified PfENR enzyme with IC50 values of <200 nM.

Synthesis and biological activity of diaryl ether inhibitors of malarial enoyl acyl carrier protein reductase. Part 2: 2'-substituted triclosan derivatives.

2'-Substituted analogs of triclosan have been synthesized to target inhibition of the key malarial enzyme Plasmodium falciparum enoyl acyl carrier protein reductase (PfENR). Many of these compounds exhibit good potency (EC50<500 nM) against in vitro cultures of drug-resistant and drug-sensitive strains of the P. falciparum parasite and modest (IC50=1-20 microM) potency against purified PfENR enzyme.

Synthesis, biological activity, and X-ray crystal structural analysis of diaryl ether inhibitors of malarial enoyl acyl carrier protein reductase. Part 1: 4'-substituted triclosan derivatives.

A structure-based approach has been taken to develop 4'-substituted analogs of triclosan that target the key malarial enzyme Plasmodium falciparum enoyl acyl carrier protein reductase (PfENR). Many of these compounds exhibit nanomolar potency against purified PfENR enzyme and modest (2-10microM) potency against in vitro cultures of drug-resistant and drug-sensitive strains of the P. falciparum parasite.

Identification of the optimal third generation antifolate against P. falciparum and P. vivax.

Inhibitors of dihydrofolate reductase (DHFR) have been mainstays in the treatment of falciparum malaria. Resistance to one of these antifolates, pyrimethamine, is now common in Plasmodium falciparum populations. Antifolates have not traditionally been recommended for treatment of vivax malaria.