Enantiospecific Reassessment of the Pharmacokinetics and Pharmacodynamics of Oral Eflornithine against Late-Stage Trypanosoma brucei gambiense Sleeping Sickness

ABSTRACTThis study aimed to characterize the stereoselective pharmacokinetics of oral eflornithine in 25 patients with late-stageTrypanosoma bruceigambiensesleeping sickness. A secondary aim was to determine the concentrations ofl- andd-eflornithine required in plasma or cerebrospinal fluid (CSF) for an efficient eradication of theT. brucei gambienseparasites. Patients were randomly allocated to receive either 100 (group I,n= 12) or 125 (group II,n= 13) mg/kg of body weight of drug every 6 h for 14 days. The concentrations ofl- andd-eflornithine in the plasma and CSF samples were measured using a stereospecific liquid chromatographic method. Nonlinear mixed-effects modeling was used to characterize the plasma pharmacokinetics. The plasma concentrations ofl-eflornithine were on average 52% (95% confidence interval [CI], 51, 54%;n= 321) of thed-enantiomer concentrations. The typical oral clearances ofl- andd-eflornithine were 17.4 (95% CI, 15.5, 19.3) and 8.23 (95% CI, 7.36, 9.10) liters/h, respectively. These differences were likely due to stereoselective intestinal absorption. The distributions of eflornithine enantiomers to the CSF were not stereoselective. A correlation was found between the probability of cure and plasma drug exposure, although it was not more pronounced for thel-enantiomer than for that of total eflornithine. This study may explain why oral treatment for late-stage human African trypanosomiasis (HAT) patients with racemic eflornithine has previously failed; the more potentl-enantiomer is present at much lower concentrations in both plasma and CSF than those of thed-enantiomer. Eflornithine stereoselective pharmacokinetics needs to be considered if an oral dosage regimen is to be explored further.

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A New NonpolarN-Hydroxy Imidazoline Lead Compound with Improved Activity in a Murine Model of Late-Stage Trypanosoma brucei brucei Infection Is Not Cross-Resistant with Diamidines

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03958-14 ◽

2014 ◽

Vol 59 (2) ◽

pp. 890-904 ◽

Cited By ~ 11

Author(s):

Carlos H. Ríos Martínez ◽

Florence Miller ◽

Kayathiri Ganeshamoorthy ◽

Fabienne Glacial ◽

Marcel Kaiser ◽

...

Keyword(s):

Trypanosoma Brucei ◽

Late Stage ◽

Parent Compound ◽

Central Nervous System Infection ◽

Sleeping Sickness ◽

Intrinsic Activity ◽

Cross Resistance ◽

Content Type

ABSTRACTTreatment of late-stage sleeping sickness requires drugs that can cross the blood-brain barrier (BBB) to reach the parasites located in the brain. We report here the synthesis and evaluation of four newN-hydroxy and 12 newN-alkoxy derivatives of bisimidazoline leads as potential agents for the treatment of late-stage sleeping sickness. These compounds, which have reduced basicity compared to the parent leads (i.e., are less ionized at physiological pH), were evaluatedin vitroagainstTrypanosoma brucei rhodesienseandin vivoin murine models of first- and second-stage sleeping sickness. Resistance profile, physicochemical parameters,in vitroBBB permeability, and microsomal stability also were determined. TheN-hydroxy imidazoline analogues were the most effectivein vivo, with 4-((1-hydroxy-4,5-dihydro-1H-imidazol-2-yl)amino)-N-(4-((1-hydroxy-4,5-dihydro-1H-imidazol-2-yl)amino)phenyl)benzamide (14d) showing 100% cures in the first-stage disease, while 15d, 16d, and 17d appeared to slightly improve survival. In addition, 14d showed weak activity in the chronic model of central nervous system infection in mice. No evidence of reduction of this compound with hepatic microsomes and mitochondria was foundin vitro, suggesting thatN-hydroxy imidazolines are metabolically stable and have intrinsic activity againstT. brucei. In contrast to its unsubstituted parent compound, the uptake of 14d inT. bruceiwas independent of known drug transporters (i.e.,T. bruceiAT1/P2 and HAPT), indicating a lower predisposition to cross-resistance with other diamidines and arsenical drugs. Hence, theN-hydroxy bisimidazolines (14d in particular) represent a new class of promising antitrypanosomal agents.

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Pharmacokinetics and Pharmacodynamics of the Nitroimidazole DNDI-0690 in Mouse Models of Cutaneous Leishmaniasis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00829-19 ◽

2019 ◽

Vol 63 (9) ◽

Cited By ~ 5

Author(s):

Gert-Jan Wijnant ◽

Simon L. Croft ◽

Raul de la Flor ◽

Mo Alavijeh ◽

Vanessa Yardley ◽

...

Keyword(s):

Cutaneous Leishmaniasis ◽

Mouse Models ◽

Drug Exposure ◽

Oral Treatment ◽

Drug Application ◽

Skin Tissue ◽

Drug Candidate ◽

Topical Formulation ◽

Content Type

ABSTRACT The nitroimidazole DNDI-0690 is a clinical drug candidate for visceral leishmaniasis (VL) that also shows potent in vitro and in vivo activity against cutaneous leishmaniasis (CL). To support further development of this compound into a patient-friendly oral or topical formulation for the treatment of CL, we investigated the free drug exposure at the dermal site of infection and subsequent elimination of the causative Leishmania pathogen. This study evaluates the pharmacokinetics (PK) and pharmacodynamics (PD) of DNDI-0690 in mouse models of CL. Skin microdialysis and Franz diffusion cell permeation studies revealed that DNDI-0690 permeated poorly (<1%) into the skin lesion upon topical drug application (0.063% [wt/vol], 30 μl). In contrast, a single oral dose of 50 mg/kg of body weight resulted in the rapid and nearly complete distribution of protein-unbound DNDI-0690 from the plasma into the infected dermis (ratio of the area under the curve [0 to 6 h] of the free DNDI-0690 concentration in skin tissue to blood [fAUC0-6 h, skin tissue/fAUC0-6 h, blood] is greater than 80%). Based on in vivo bioluminescence imaging, two doses of 50 mg/kg DNDI-0690 were sufficient to reduce the Leishmania mexicana parasite load by 100-fold, while 6 such doses were needed to achieve similar killing of L. major; this was confirmed by quantitative PCR. The combination of rapid accumulation and potent activity in the Leishmania-infected dermis indicates the potential of DNDI-0690 as a novel oral treatment for CL.

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Essential Assembly Factor Rpf2 Forms Novel Interactions within the 5S RNP in Trypanosoma brucei

mSphere ◽

10.1128/msphere.00394-17 ◽

2017 ◽

Vol 2 (5) ◽

Cited By ~ 4

Author(s):

Anyango D. Kamina ◽

Daniel Jaremko ◽

Linda Christen ◽

Noreen Williams

Keyword(s):

Trypanosoma Brucei ◽

Ribosome Biogenesis ◽

Sleeping Sickness ◽

5S Rrna ◽

Ribonucleoprotein Particle ◽

Content Type ◽

Assembly Factor ◽

Specific Proteins ◽

First Time ◽

Ribosome Formation

ABSTRACT Trypanosoma brucei is the parasitic protozoan that causes African sleeping sickness. Ribosome assembly is essential for the survival of this parasite through the different host environments it encounters during its life cycle. The assembly of the 5S ribonucleoprotein particle (5S RNP) functions as one of the regulatory checkpoints during ribosome biogenesis. We have previously characterized the 5S RNP in T. brucei and showed that trypanosome-specific proteins P34 and P37 are part of this complex. In this study, we characterize for the first time the interactions of the homolog of the assembly factor Rpf2 with members of the 5S RNP in another organism besides fungi. Our studies show that Rpf2 is essential in T. brucei and that it forms unique interactions within the 5S RNP, particularly with P34 and P37. These studies have identified parasite-specific interactions that can potentially function as new therapeutic targets against sleeping sickness. Ribosome biogenesis is a highly complex and conserved cellular process that is responsible for making ribosomes. During this process, there are several assembly steps that function as regulators to ensure proper ribosome formation. One of these steps is the assembly of the 5S ribonucleoprotein particle (5S RNP) in the central protuberance of the 60S ribosomal subunit. In eukaryotes, the 5S RNP is composed of 5S rRNA, ribosomal proteins L5 and L11, and assembly factors Rpf2 and Rrs1. Our laboratory previously showed that in Trypanosoma brucei, the 5S RNP is composed of 5S rRNA, L5, and trypanosome-specific RNA binding proteins P34 and P37. In this study, we characterize an additional component of the 5S RNP, the T. brucei homolog of Rpf2. This is the first study to functionally characterize interactions mediated by Rpf2 in an organism other than fungi. T. brucei Rpf2 (TbRpf2) was identified from tandem affinity purification using extracts prepared from protein A-tobacco etch virus (TEV)-protein C (PTP)-tagged L5, P34, and P37 cell lines, followed by mass spectrometry analysis. We characterized the binding interactions between TbRpf2 and the previously characterized members of the T. brucei 5S RNP. Our studies show that TbRpf2 mediates conserved binding interactions with 5S rRNA and L5 and that TbRpf2 also interacts with trypanosome-specific proteins P34 and P37. We performed RNA interference (RNAi) knockdown of TbRpf2 and showed that this protein is essential for the survival of the parasites and is critical for proper ribosome formation. These studies provide new insights into a critical checkpoint in the ribosome biogenesis pathway in T. brucei. IMPORTANCE Trypanosoma brucei is the parasitic protozoan that causes African sleeping sickness. Ribosome assembly is essential for the survival of this parasite through the different host environments it encounters during its life cycle. The assembly of the 5S ribonucleoprotein particle (5S RNP) functions as one of the regulatory checkpoints during ribosome biogenesis. We have previously characterized the 5S RNP in T. brucei and showed that trypanosome-specific proteins P34 and P37 are part of this complex. In this study, we characterize for the first time the interactions of the homolog of the assembly factor Rpf2 with members of the 5S RNP in another organism besides fungi. Our studies show that Rpf2 is essential in T. brucei and that it forms unique interactions within the 5S RNP, particularly with P34 and P37. These studies have identified parasite-specific interactions that can potentially function as new therapeutic targets against sleeping sickness.

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Efficacy of the Novel Diamidine Compound 2,5-Bis(4-Amidinophenyl)- Furan-Bis-O-Methlylamidoxime (Pafuramidine, DB289) against Trypanosoma brucei rhodesiense Infection in Vervet Monkeys after Oral Administration

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00831-08 ◽

2008 ◽

Vol 53 (3) ◽

pp. 953-957 ◽

Cited By ~ 25

Author(s):

R. E. Mdachi ◽

J. K. Thuita ◽

J. M. Kagira ◽

J. M. Ngotho ◽

G. A. Murilla ◽

...

Keyword(s):

Trypanosoma Brucei ◽

Late Stage ◽

Early Stage ◽

Vervet Monkey ◽

Sleeping Sickness ◽

Vervet Monkeys ◽

Trypanosoma Brucei Rhodesiense ◽

Dose Rates ◽

Group 4 ◽

Group 5

ABSTRACT Owing to the lack of oral drugs for human African trypanosomiasis, patients have to be hospitalized for 10 to 30 days to facilitate treatment with parenterally administered medicines. The efficacy of a novel orally administered prodrug, 2,5-bis(4-amidinophenyl)-furan-bis-O-methlylamidoxime (pafuramidine, DB289), was tested in the vervet monkey (Chlorocebus [Cercopithecus] aethiops) model of sleeping sickness. Five groups of three animals each were infected intravenously with 104 Trypanosoma brucei rhodesiense KETRI 2537 cells. On the seventh day postinfection (p.i.) in an early-stage infection, animals in groups 1, 2, and 3 were treated orally with pafuramidine at dose rates of 1, 3, or 10 mg/kg of body weight, respectively, for five consecutive days. The animals in groups 4 and 5 were treated with 10 mg/kg for 10 consecutive days starting on the 14th day p.i. (group 4) or on the 28th day p.i. (group 5), when these animals were in the late stage of the disease. In the groups treated in the early stage, 10 mg/kg of pafuramidine completely cured all three monkeys, whereas lower doses of 3 mg/kg and 1 mg/kg cured only one of three and zero of three monkeys, respectively. Treatment of late-stage infections resulted in cure rates of one of three (group 4) and zero of three (group 5) monkeys. These studies demonstrated that pafuramidine was orally active in monkeys with early-stage T. brucei rhodesiense infections at dose rates above 3 mg/kg for 5 days. It was also evident that the drug attained only minimal efficacy against late-stage infections, indicating the limited ability of the molecule to cross the blood-brain barrier. This study has shown that oral diamidines have potential for the treatment of early-stage sleeping sickness.

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Assessment of an abridged melarsoprol treatment schedule against late stage Trypanosoma brucei rhodesiense sleeping sickness, multinational phase II study (proof of concept)

http://isrctn.org/> ◽

10.1186/isrctn40537886 ◽

2012 ◽

Author(s):

Johannes Blum

Keyword(s):

Trypanosoma Brucei ◽

Phase Ii ◽

Late Stage ◽

Phase Ii Study ◽

Sleeping Sickness ◽

Treatment Schedule ◽

Proof Of Concept ◽

Trypanosoma Brucei Rhodesiense

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Basic Biology of Trypanosoma brucei with reference to the development of chemotherapies

Current Pharmaceutical Design ◽

10.2174/1381612827666210119105008 ◽

2021 ◽

Vol 27 ◽

Author(s):

Samuel Dean

Keyword(s):

Trypanosoma Brucei ◽

Late Stage ◽

Antigenic Variation ◽

Molecular Genetic ◽

Sleeping Sickness ◽

Tsetse Fly ◽

Tsetse Flies ◽

African Sleeping Sickness ◽

Stage Disease ◽

Late Stage Disease

: Trypanosoma brucei are protozoan parasites that causes the lethal human disease African sleeping sickness, and the economically devastating disease of cattle, Nagana. African sleeping sickness, or Human African Trypanosomiasis (HAT) threatens 65 million people, and animal trypanosomiasis makes large areas of farmland unusable. There is no vaccine and licenced therapies against the most severe, late-stage disease are toxic, impractical and ineffective. Trypanosomes are transmitted by tsetse flies and HAT is therefore predominantly confined to the tsetse fly belt in subSaharan African. They are exclusively extracellular, and they differentiate between at least seven developmental forms that are highly adapted to host and vector niches. In the mammalian (human) host they inhabit the blood, cerebrospinal fluid (late stage disease), skin and adipose fat. In the tsetse fly vector, they travel from the tsetse midgut to the salivary glands via the ectoperitrophic space and proventriculus. Trypanosomes are evolutionarily divergent compared with most branches of eukaryotic life. Perhaps most famous for their extraordinary mechanisms of monoallelic gene expression and antigenic variation, they have also been investigated because much of their biology is either highly unconventional or extreme. Moreover, in addition to their importance as pathogens, many researchers have been attracted to the field because trypanosomes have some of the most advanced molecular genetic tools and database resources of any model system. The following will cover just some aspects of trypanosome biology and how its divergent biochemistry has been leveraged to develop drugs to treat African Sleeping sickness. It is by no means intended to be a comprehensive survey of trypanosome features. Rather, it is hoped that it will present trypanosomes as one of the most fascinating and tractable systems in which to do discovery biology.

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Antitrypanosomal Activity of Fexinidazole, a New Oral Nitroimidazole Drug Candidate for Treatment of Sleeping Sickness

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00246-11 ◽

2011 ◽

Vol 55 (12) ◽

pp. 5602-5608 ◽

Cited By ~ 83

Author(s):

Marcel Kaiser ◽

Michael A. Bray ◽

Monica Cal ◽

Bernadette Bourdin Trunz ◽

Els Torreele ◽

...

Keyword(s):

Oral Treatment ◽

Sleeping Sickness ◽

Drug Candidate ◽

Pharmacokinetic Data ◽

Parent Molecule ◽

Content Type ◽

Trypanocidal Activity ◽

Parasite Strains

ABSTRACTFexinidazole is a 5-nitroimidazole drug currently in clinical development for the treatment of human sleeping sickness (human African trypanosomiasis [HAT]), caused by infection with species of the protozoan parasiteTrypanosoma brucei. The compound and its two principal metabolites, sulfoxide and sulfone, have been assessed for their ability to kill a range ofT. bruceiparasite strainsin vitroand to cure both acute and chronic HAT disease models in the mouse. The parent molecule and both metabolites have shown trypanocidal activityin vitroin the 0.7-to-3.3 μM (0.2-to-0.9 μg/ml) range against all parasite strains tested.In vivo, fexinidazole is orally effective in curing both acute and chronic diseases in the mouse at doses of 100 mg/kg of body weight/day for 4 days and 200 mg/kg/day for 5 days, respectively. Pharmacokinetic data indicate that it is likely that the sulfoxide and sulfone metabolites provide most, if not all, of thein vivokilling activity. Fexinidazole and its metabolites require up to 48 h exposure in order to induce maximal trypanocidal efficacyin vitro. The parent drug and its metabolites show noin vitrocross-reactivity in terms of trypanocidal activity with either themselves or other known trypanocidal drugs in use in humans. Thein vitroandin vivoantitrypanosomal activities of fexinidazole and its two principal metabolites provide evidence that the compound has the potential to be an effective oral treatment for both theT. b. gambienseandT. b. rhodesienseforms of human sleeping sickness and both stages of the disease.

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Pharmacodynamics of Tebipenem: New Options for Oral Treatment of Multidrug-Resistant Gram-Negative Infections

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00603-19 ◽

2019 ◽

Vol 63 (8) ◽

Cited By ~ 8

Author(s):

Laura McEntee ◽

Adam Johnson ◽

Nicola Farrington ◽

Jennifer Unsworth ◽

Aaron Dane ◽

...

Keyword(s):

Drug Exposure ◽

Drug Product ◽

Oral Treatment ◽

Phase Iii ◽

Dose Fractionation ◽

Infection Model ◽

Content Type ◽

Drug Concentrations ◽

Tebipenem Pivoxil ◽

Tract Infections

ABSTRACT Tebipenem pivoxil HBr (TBPM-PI-HBr) is a novel orally bioavailable carbapenem. The active moiety is tebipenem. Tebipenem pivoxil is licensed for use in Japan in children with ear, nose, and throat infections and respiratory infections. The HBr salt was designed to improve drug substance and drug product properties, including stability. TBPM-PI-HBr is now being developed as an agent for the treatment of complicated urinary tract infections (cUTI) in adults. The pharmacokinetics-pharmacodynamics of tebipenem were studied in a well-characterized neutropenic murine thigh infection model. Plasma drug concentrations were measured using liquid chromatography-tandem mass spectrometry. Dose fractionation experiments were performed after establishing dose-response relationships. The magnitude of drug exposure required for stasis was established using 11 strains of Enterobacteriaceae (Escherichia coli, n = 6; Klebsiella pneumoniae, n = 5) with a variety of resistance mechanisms. The relationship between drug exposure and the emergence of resistance was established in a hollow-fiber infection model (HFIM). Tebipenem exhibited time-dependent pharmacodynamics that were best described by the free drug area under the concentration-time curve (fAUC0-24)/MIC corrected for the length of the dosing interval (fAUC0–24/MIC · 1/tau). The pharmacodynamics of tebipenem versus E. coli and K. pneumoniae were comparable, as was the response of strains possessing extended-spectrum β-lactamases versus the wild type. The median fAUC0-24/MIC · 1/tau value for the achievement of stasis in the 11 strains was 23. Progressively more fractionated regimens in the HFIM resulted in the suppression of resistance. An fAUC0-24/MIC · 1/tau value of 34.58 to 51.87 resulted in logarithmic killing and the suppression of resistance. These data and analyses will be used to define the regimen for a phase III study of adult patients with cUTI.

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The Oral Antimalarial Drug Tafenoquine Shows Activity against Trypanosoma brucei

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00879-15 ◽

2015 ◽

Vol 59 (10) ◽

pp. 6151-6160 ◽

Cited By ~ 16

Author(s):

Luis Carvalho ◽

Marta Martínez-García ◽

Ignacio Pérez-Victoria ◽

José Ignacio Manzano ◽

Vanessa Yardley ◽

...

Keyword(s):

Trypanosoma Brucei ◽

Antimalarial Drug ◽

Protozoan Parasite ◽

Sleeping Sickness ◽

Phase Iii ◽

Content Type ◽

Clinical Phase ◽

Intracellular Ca ◽

Cytoplasmic Content

ABSTRACTThe protozoan parasiteTrypanosoma bruceicauses human African trypanosomiasis, or sleeping sickness, a neglected tropical disease that requires new, safer, and more effective treatments. Repurposing oral drugs could reduce both the time and cost involved in sleeping sickness drug discovery. Tafenoquine (TFQ) is an oral antimalarial drug belonging to the 8-aminoquinoline family which is currently in clinical phase III. We show here that TFQ efficiently kills differentT. bruceispp. in the submicromolar concentration range. Our results suggest that TFQ accumulates into acidic compartments and induces a necrotic process involving cell membrane disintegration and loss of cytoplasmic content, leading to parasite death. Cell lysis is preceded by a wide and multitarget drug action, affecting the lysosome, mitochondria, and acidocalcisomes and inducing a depolarization of the mitochondrial membrane potential, elevation of intracellular Ca2+, and production of reactive oxygen species. This is the first report of an 8-aminoquinoline demonstrating significantin vitroactivity againstT. brucei.

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