Toxic Profile of Benznidazole in Patients with Chronic Chagas Disease: Risk Factors and Comparison of the Product from Two Different Manufacturers

Efficacy of three benznidazole dosing strategies for adults living with chronic Chagas disease (MULTIBENZ): an international, randomised, double-blind, phase 2b trial

BACKGROUND

Treatment with benznidazole for chronic Chagas disease is associated with low cure rates and substantial toxicity. We aimed to compare the parasitological efficacy and safety of 3 different benznidazole regimens in adult patients with chronic Chagas disease.

METHODS

The MULTIBENZ trial was an international, randomised, double-blind, phase 2b trial performed in Argentina, Brazil, Colombia, and Spain. We included participants aged 18 years and older diagnosed with Chagas disease with two different serological tests and detectable T cruzi DNA by qPCR in blood. Previously treated people, pregnant women, and people with severe cardiac forms were excluded. Participants were randomly assigned 1:1:1, using a balanced block randomisation scheme stratified by country, to receive benznidazole at three different doses: 300 mg/day for 60 days (control group), 150 mg/day for 60 days (low dose group), or 400 mg/day for 15 days (short treatment group). The primary outcome was the proportion of patients with a sustained parasitological negativity by qPCR during a follow-up period of 12 months. The primary safety outcome was the proportion of people who permanently discontinued the treatment. Both primary efficacy analysis and primary safety analysis were done in the intention-to-treat population. The trial is registered with EudraCT, 2016-003789-21, and ClinicalTrials.gov, NCT03191162, and is completed.

FINDINGS

From April 20, 2017, to Sept 20, 2020, 245 people were enrolled, and 234 were randomly assigned: 78 to the control group, 77 to the low dose group, and 79 to the short treatment group. Sustained parasitological negativity was observed in 42 (54%) of 78 participants in the control group, 47 (61%) of 77 in the low dose group, and 46 (58%) of 79 in the short treatment group. Odds ratios were 1·41 (95% CI 0·69-2·88; p=0·34) when comparing the low dose and control groups and 1·23 (0·61-2·50; p=0·55) when comparing short treatment and control groups. 177 participants (76%) had an adverse event: 62 (79%) in the control group, 56 (73%) in the low dose group, and 59 (77%) in the short treatment group. However, discontinuations were less frequent in the short treatment group compared with the control group (2 [2%] vs 11 [14%]; OR 0·20, 95% CI 0·04-0·95; p=0·044).

INTERPRETATION

Participants had a similar parasitological responses. However, reducing the usual treatment from 8 weeks to 2 weeks might maintain the same response while facilitating adherence and increasing treatment coverage. These findings should be confirmed in a phase 3 clinical trial.

FUNDING

European Community's 7th Framework Programme.

Chagas Disease: A Silent Threat for Dogs and Humans

Chagas disease (CD) is a vector-borne Neglected Zoonotic Disease (NZD) caused by a flagellate protozoan, Trypanosoma cruzi, that affects various mammalian species across America, including humans and domestic animals. However, due to an increase in population movements and new routes of transmission, T. cruzi infection is presently considered a worldwide health concern, no longer restricted to endemic countries. Dogs play a major role in the domestic cycle by acting very efficiently as reservoirs and allowing the perpetuation of parasite transmission in endemic areas. Despite the significant progress made in recent years, still there is no vaccine against human and animal disease, there are few drugs available for the treatment of human CD, and there is no standard protocol for the treatment of canine CD. In this review, we highlight human and canine Chagas Disease in its different dimensions and interconnections. Dogs, which are considered to be the most important peridomestic reservoir and sentinel for the transmission of T. cruzi infection in a community, develop CD that is clinically similar to human CD. Therefore, an integrative approach, based on the One Health concept, bringing together the advances in genomics, immunology, and epidemiology can lead to the effective development of vaccines, new treatments, and innovative control strategies to tackle CD.

The impact of vaccine-linked chemotherapy on liver health in a mouse model of chronic Trypanosoma cruzi infection

BACKGROUND

Chagas disease, chronic infection with Trypanosoma cruzi, mainly manifests as cardiac disease. However, the liver is important for both controlling parasite burdens and metabolizing drugs. Notably, high doses of anti-parasitic drug benznidazole (BNZ) causes liver damage. We previously showed that combining low dose BNZ with a prototype therapeutic vaccine is a dose sparing strategy that effectively reduced T. cruzi induced cardiac damage. However, the impact of this treatment on liver health is unknown. Therefore, we evaluated several markers of liver health after treatment with low dose BNZ plus the vaccine therapy in comparison to a curative dose of BNZ.

METHODOLOGY

Female BALB/c mice were infected with a bioluminescent T. cruzi H1 clone for approximately 70 days, then randomly divided into groups of 15 mice each. Mice were treated with a 25mg/kg BNZ, 25μg Tc24-C4 protein/ 5μg E6020-SE (Vaccine), 25mg/kg BNZ followed by vaccine, or 100mg/kg BNZ (curative dose). At study endpoints we evaluated hepatomegaly, parasite burden by quantitative PCR, cellular infiltration by histology, and expression of B-cell translocation gene 2(BTG2) and Peroxisome proliferator-activated receptor alpha (PPARα) by RT-PCR. Levels of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were quantified from serum.

RESULTS

Curative BNZ treatment significantly reduced hepatomegaly, liver parasite burdens, and the quantity of cellular infiltrate, but significantly elevated serum levels of ALT, AST, and LDH. Low BNZ plus vaccine did not significantly affect hepatomegaly, parasite burdens or the quantity of cellular infiltrate, but only elevated ALT and AST. Low dose BNZ significantly decreased expression of both BTG2 and PPARα, and curative BNZ reduced expression of BTG2 while low BNZ plus vaccine had no impact.

CONCLUSIONS

These data confirm toxicity associated with curative doses of BNZ and suggest that while dose sparing low BNZ plus vaccine treatment does not reduce parasite burdens, it better preserves liver health.

Immunomodulatory proteins from hookworms reduce cardiac inflammation and modulate regulatory responses in a mouse model of chronic Trypanosoma cruzi infection

Introduction

Hookworms are parasitic helminths that secrete a variety of proteins that induce anti-inflammatory immune responses, stimulating increased CD4 + Foxp3+ regulatory T cells and IL-10 production. Hookworm-derived recombinant proteins AIP-1 and AIP-2 have been shown to reduce inflammation in mouse models of inflammatory bowel disease and inflammatory airway disease by inducing CD4+Foxp3+ cells and IL-10 production. In contrast, chronic infection with the protozoal parasite Trypanosoma cruzi, the causative agent of Chagas disease, leads to chronic inflammation in tissues. Persistence of the parasites in tissues drives chronic low-grade inflammation, with increased infiltration of inflammatory cells into the heart, accompanied by increased production of inflammatory cytokines. There are no current antiparasitic drugs that effectively reduce or prevent chronic myocarditis caused by the onset of Chagas disease, thus new therapies are urgently needed. Therefore, the impact of AIP-1 and AIP-2 on myocarditis was investigated in a mouse model of chronic T. cruzi infection.

Methods

Female BALB/c mice infected with bioluminescent T. cruzi H1 strain trypomastigotes for 70 days were treated once daily for 7 days with 1mg/kg AIP-1 or AIP-2 protein by intraperitoneal injection. Control mice were left untreated or treated once daily for 14 days with 25mg/kg aspirin in drinking water. At 84 days of infection, splenocytes, cardiac tissue and serum were collected for evaluation.

Results

Treatment with both AIP-1 and AIP-2 proteins significantly reduced cardiac cellular infiltration, and reduced cardiac levels of IFNγ, IL-6 and IL-2. AIP-2 treatment reduced cardiac expression of COX-2. Further, while incubation with AIP-1 and AIP-2 proteins did not induce a significant upregulation of an immunoregulatory phenotype in dendritic cells (DC), there was a modest upregulation of CD11c +CD11b+MHCII+SIRPα+ expression, suggesting a regulatory phenotype. Ex-vivo stimulation of splenocytes from the treatment groups with AIP-1 loaded DC induced reduced levels of cytotoxic and pro-inflammatory T cells, stimulation with AIP-2 loaded DC specifically induced enhanced levels of CD4+CD25+Foxp3+ regulatory T cells among treatment groups.

Discussion

All in vivo and in vitro results demonstrate that hookworm-derived AIP-1 and AIP-2 proteins reduce T. cruzi induced cardiac inflammation, possibly through multiple anti-inflammatory mechanisms.

The impact of vaccine-linked chemotherapy on liver health in a mouse model of chronic Trypanosoma cruzi infection

Background

Chagas disease, chronic infection with Trypanosoma cruzi, mainly manifests as cardiac disease. However, the liver is important for both controlling parasite burdens and metabolizing drugs. Notably, high doses of anti-parasitic drug benznidazole (BNZ) causes liver damage. We previously showed that combining low dose BNZ with a prototype therapeutic vaccine is a dose sparing strategy that effectively reduced T. cruzi induced cardiac damage. However, the impact of this treatment on liver health is unknown. Therefore, we evaluated several markers of liver health after treatment with low dose BNZ plus the vaccine therapy in comparison to a curative dose of BNZ.

Methodology

Female BALB/c mice were infected with a bioluminescent T. cruzi H1 clone for approximately 70 days, then randomly divided into groups of 15 mice each. Mice were treated with a 25mg/kg BNZ, 25μg Tc24-C4 protein/5μg E6020-SE (Vaccine), 25mg/kg BNZ followed by vaccine, or 100mg/kg BNZ (curative dose). At study endpoints we evaluated hepatomegaly, parasite burden by quantitative PCR, cellular infiltration by histology, and expression of B-cell translocation gene 2(BTG2) and Peroxisome proliferator-activated receptor alpha (PPARα) by RT-PCR. Levels of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were quantified from serum.

Results

Curative BNZ treatment significantly reduced hepatomegaly, liver parasite burdens, and the quantity of cellular infiltrate, but significantly elevated serum levels of ALT, AST, and LDH. Low BNZ plus vaccine did not significantly affect hepatomegaly, parasite burdens or the quantity of cellular infiltrate, but only elevated ALT and AST. Low dose BNZ significantly decreased expression of both BTG2 and PPARα, and curative BNZ reduced expression of BTG2 while low BNZ plus vaccine had no impact.

Conclusions

These data confirm toxicity associated with curative doses of BNZ and suggest that the dose sparing low BNZ plus vaccine treatment better preserves liver health.

Molecular targets for Chagas disease: validation, challenges and lead compounds for widely exploited targets

INTRODUCTION

Chagas disease (CD) imposes social and economic burdens, yet the available treatments have limited efficacy in the disease's chronic phase and cause serious adverse effects. To address this challenge, target-based approaches are a possible strategy to develop new, safe, and active treatments for both phases of the disease.

AREAS COVERED

This review delves into target-based approaches applied to CD drug discovery, emphasizing the studies from the last five years. We highlight the proteins cruzain (CZ), trypanothione reductase (TR), sterol 14 α-demethylase (CPY51), iron superoxide dismutase (Fe-SOD), proteasome, cytochrome b (Cytb), and cleavage and polyadenylation specificity factor 3 (CPSF3), chosen based on their biological and chemical validation as drug targets. For each, we discuss its biological relevance and validation as a target, currently related challenges, and the status of the most promising inhibitors.

EXPERT OPINION

Target-based approaches toward developing potential CD therapeutics have yielded promising leads in recent years. We expect a significant advance in this field in the next decade, fueled by the new options for Trypanosoma cruzi genetic manipulation that arose in the past decade, combined with recent advances in computational chemistry and chemical biology.

Theracurmin Modulates Cardiac Inflammation in Experimental Model of Trypanosoma cruzi Infection

Theracurmin is a nanoparticle formulation derived from curcumin, a bioactive compound known for its antioxidant and anti-inflammatory properties. Trypanosoma cruzi, the etiological agent of Chagas disease, triggers an intense inflammatory response in mammals and also causes severe tissue damage. To evaluate the immunomodulatory and antiparasitic effects of Theracurmin, Swiss mice were experimentally infected with 10³ trypomastigote forms of the Colombian strain of T. cruzi and submitted to daily therapy with 30 mg/kg of Theracurmin. In addition, daily benznidazole therapy (100 mg/kg) was performed as a positive control. We evaluated the systemic and tissue parasitism, the survival and the body mass rate, the release of inflammatory mediators (TNF, IL-6, IL-15, CCL2 and creatine kinase) and the tissue inflammation at day 30 post-infection. Theracurmin therapy reduced the parasitemia curve without altering the animals' survival rate, and it protected mice from losing body mass. Theracurmin also reduced CCL2 in cardiac tissue, IL-15 in cardiac and skeletal tissue, and plasma CK. Even without effects on TNF and IL-6 production and tissue amastigote nests, Theracurmin reduced the leukocyte infiltrate in both evaluated tissues, even in the case of more effective results observed to the benznidazole treatment. Our data suggest Theracurmin has an immunomodulatory (CCL2, IL-15, CK and tissue leukocyte infiltration) and a trypanocidal effect (on circulating parasites) during experimental infection triggered by the Colombian strain of T. cruzi. Further investigations are necessary to comprehend the Theracurmin role performed in combination with benznidazole or other potential anti-T. cruzi chemical compounds.

Vaccine-linked chemotherapy improves cardiac structure and function in a mouse model of chronic Chagas disease

Introduction

Chagas disease, caused by chronic infection with the protozoan parasite Trypanosoma cruzi, affects 6-7 million people worldwide. The major clinical manifestation of Chagas disease is chronic Chagasic cardiomyopathy (CCC), which encompasses a spectrum of symptoms including arrhythmias, hypertrophy, dilated cardiomyopathy, heart failure, and sudden death. Current treatment is limited to two antiparasitic drugs, benznidazole (BNZ) and nifurtimox, but both have limited efficacy to halt the progression of CCC. We developed a vaccine-linked chemotherapy strategy using our vaccine consisting of recombinant Tc24-C4 protein and a TLR-4 agonist adjuvant in a stable squalene emulsion, in combination with low dose benznidazole treatment. We previously demonstrated in acute infection models that this strategy parasite specific immune responses, and reduced parasite burdens and cardiac pathology. Here, we tested our vaccine-linked chemotherapy strategy in a mouse model of chronic T. cruzi infection to evaluate the effect on cardiac function.

Methods

Female BALB/c mice infected with 500 blood form T. cruzi H1 strain trypomastigotes were treated beginning 70 days after infection with a low dose of BNZ and either low or high dose of vaccine, in both sequential and concurrent treatments streams. Control mice were untreated, or administered only one treatment. Cardiac health was monitored throughout the course of treatment by echocardiography and electrocardiograms. Approximately 8 months after infection, endpoint histopathology was performed to measure cardiac fibrosis and cellular infiltration.

Results

Vaccine-linked chemotherapy improved cardiac function as evidenced by amelioration of altered left ventricular wall thickness, left ventricular diameter, as well as ejection fraction and fractional shortening by approximately 4 months of infection, corresponding to two months after treatment was initiated. At study endpoint, vaccine-linked chemotherapy reduced cardiac cellular infiltration, and induced significantly increased antigen specific IFN-γ and IL-10 release from splenocytes, as well as a trend toward increased IL-17A.

Discussion

These data suggest that vaccine-linked chemotherapy ameliorates changes in cardiac structure and function induced by infection with T. cruzi. Importantly, similar to our acute model, the vaccine-linked chemotherapy strategy induced durable antigen specific immune responses, suggesting the potential for a long lasting protective effect. Future studies will evaluate additional treatments that can further improve cardiac function during chronic infection.

A Review on the Immunological Response against Trypanosoma cruzi

Chagas disease is a chronic systemic infection transmitted by Trypanosoma cruzi. Its life cycle consists of different stages in vector insects and host mammals. Trypanosoma cruzi strains cause different clinical manifestations of Chagas disease alongside geographic differences in morbidity and mortality. Natural killer cells provide the cytokine interferon-gamma in the initial phases of T. cruzi infection. Phagocytes secrete cytokines that promote inflammation and activation of other cells involved in defence. Dendritic cells, monocytes and macrophages modulate the adaptive immune response, and B lymphocytes activate an effective humoral immune response to T. cruzi. This review focuses on the main immune mechanisms acting during T. cruzi infection, on the strategies activated by the pathogen against the host cells, on the processes involved in inflammasome and virulence factors and on the new strategies for preventing, controlling and treating this disease.

Tolerance and Adherence of Patients with Chronic Chagas Disease Treated with Benznidazole

BACKGROUND

Chagas disease (CD) treatment is commonly associated with a high incidence of adverse effects. It is crucial to study and update these adverse effects to improve the existing knowledge of which drugs to use and to clarify the information presented to patients.

METHODS

We analyzed the adverse effects of benznidazole in two cohorts of patients: a large retrospective study and a small prospective study.

RESULTS

This large retrospective study described the most and least common adverse effects in our area and characterized our Chagas disease population. This prospective study, along with a close follow-up of the treatment, detected more adverse effects and enhanced the patients' perception of the disease and treatment.

CONCLUSIONS

This information is important for preventing non-medical-related withdrawals and for removing baseless fears. Better knowledge of patients could help us provide better care.

Parasite Metalo-aminopeptidases as Targets in Human Infectious Diseases

BACKGROUND

Parasitic human infectious diseases are a worldwide health problem due to the increased resistance to conventional drugs. For this reason, the identification of novel molecular targets and the discovery of new chemotherapeutic agents are urgently required. Metalo- aminopeptidases are promising targets in parasitic infections. They participate in crucial processes for parasite growth and pathogenesis.

OBJECTIVE

In this review, we describe the structural, functional and kinetic properties, and inhibitors, of several parasite metalo-aminopeptidases, for their use as targets in parasitic diseases.

CONCLUSION

Plasmodium falciparum M1 and M17 aminopeptidases are essential enzymes for parasite development, and M18 aminopeptidase could be involved in hemoglobin digestion and erythrocyte invasion and egression. Trypanosoma cruzi, T. brucei and Leishmania major acidic M17 aminopeptidases can play a nutritional role. T. brucei basic M17 aminopeptidase down-regulation delays the cytokinesis. The inhibition of Leishmania basic M17 aminopeptidase could affect parasite viability. L. donovani methionyl aminopeptidase inhibition prevents apoptosis but not the parasite death. Decrease in Acanthamoeba castellanii M17 aminopeptidase activity produces cell wall structural modifications and encystation inhibition. Inhibition of Babesia bovis growth is probably related to the inhibition of the parasite M17 aminopeptidase, probably involved in host hemoglobin degradation. Schistosoma mansoni M17 aminopeptidases inhibition may affect parasite development, since they could participate in hemoglobin degradation, surface membrane remodeling and eggs hatching. Toxoplasma gondii M17 aminopeptidase inhibition could attenuate parasite virulence, since it is apparently involved in the hydrolysis of cathepsin Cs- or proteasome-produced dipeptides and/or cell attachment/invasion processes. These data are relevant to validate these enzymes as targets.

Trypanosoma cruzi iron superoxide dismutases: insights from phylogenetics to chemotherapeutic target assessment

Background

Components of the antioxidant defense system in Trypanosoma cruzi are potential targets for new drug development. Superoxide dismutases (SODs) constitute key components of antioxidant defense systems, removing excess superoxide anions by converting them into oxygen and hydrogen peroxide. The main goal of the present study was to investigate the genes coding for iron superoxide dismutase (FeSOD) in T. cruzi strains from an evolutionary perspective.

Methods

In this study, molecular biology methods and phylogenetic studies were combined with drug assays. The FeSOD-A and FeSOD-B genes of 35 T. cruzi strains, belonging to six discrete typing units (Tcl–TcVI), from different hosts and geographical regions were amplified by PCR and sequenced using the Sanger method. Evolutionary trees were reconstructed based on Bayesian inference and maximum likelihood methods. Drugs that potentially interacted with T. cruzi FeSODs were identified and tested against the parasites.

Results

Our results suggest that T. cruzi FeSOD types are members of distinct families. Gene copies of FeSOD-A (n = 2), FeSOD-B (n = 4) and FeSOD-C (n = 4) were identified in the genome of the T. cruzi reference clone CL Brener. Phylogenetic inference supported the presence of two functional variants of each FeSOD type across the T. cruzi strains. Phylogenetic trees revealed a monophyletic group of FeSOD genes of T. cruzi TcIV strains in both distinct genes. Altogether, our results support the hypothesis that gene duplication followed by divergence shaped the evolution of T. cruzi FeSODs. Two drugs, mangafodipir and polaprezinc, that potentially interact with T. cruzi FeSODs were identified and tested in vitro against amastigotes and trypomastigotes: mangafodipir had a low trypanocidal effect and polaprezinc was inactive.

Conclusions

Our study contributes to a better understanding of the molecular biodiversity of T. cruzi FeSODs. Herein we provide a successful approach to the study of gene/protein families as potential drug targets.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05319-2.

Drug associations as alternative and complementary therapy for neglected tropical diseases

The present paper aims to establish different treatments for neglected tropical disease by a survey on drug conjugations and possible fixed-dose combinations (FDC) used to obtain alternative, safer and more effective treatments. The source databases used were Science Direct and PubMed/Medline, in the intervals between 2015 and 2021 with the drugs key-words or diseases, like "schistosomiasis", "praziquantel", "malaria", "artesunate", "Chagas' disease", "benznidazole", "filariasis", diethylcarbamazine", "ivermectin", " albendazole". 118 works were the object of intense analysis, other articles and documents were used to increase the quality of the studies, such as consensuses for harmonizing therapeutics and historical articles. As a result, an effective NTD control can be achieved when different public health approaches are combined with interventions guided by the epidemiology of each location and the availability of appropriate measures to detect, prevent and control disease. It was also possible to verify that the FDCs promote a simplification of the therapeutic regimen, which promotes better patient compliance and enables a reduction in the development of parasitic resistance, requiring further studies aimed at resistant strains, since the combined APIs usually act by different mechanisms or at different target sites. In addition to eliminating the process of developing a new drug based on the identification and validation of active compounds, which is a complex, long process and requires a strong long-term investment, other advantages that FDCs have are related to productive gain and gain from the industrial plant, which can favor and encourage the R&D of new FDCs not only for NTDs but also for other diseases that require the use of more than one drug.

Trypanocidal treatment of Chagas disease

Chagas disease is a neglected parasitosis caused by the protozoan parasite Trypanosoma cruzi. This infection is present in most Latin American countries, although, due to migratory movements, it is a growing cause for concern in non-endemic countries. The only two drugs currently available for its treatment-benznidazole and nifurtimox-were marketed 50 years ago. While they are very effective for acute and recent infection, and for the prevention of maternofoetal transmission, their efficacy declines in people who have chronic infection, especially those older than 18 years of age. In the presence of visceral involvement, parasiticidal treatment is of little or no value. The safety profile of both drugs is far from ideal, with frequent adverse events and high rates of drug discontinuation, mainly in adults. So far, new drugs and new strategies have not been shown to improve the results of the current nitroimidazoles, although the results are promising. In this review, we focus on the aspects that allow clinicians to make the best use of currently available drugs. In addition, we discuss new therapeutic options and ongoing research in the field.

An aromatic imidazoline derived from chloroquinoline triggers cell cycle arrest and inhibits with high selectivity the Trypanosoma cruzi mammalian host-cells infection

Trypanosoma cruzi is a hemoflagellated parasite causing Chagas disease, which affects 6-8 million people in the Americas. More than one hundred years after the description of this disease, the available drugs for treating the T. cruzi infection remain largely unsatisfactory. Chloroquinoline and arylamidine moieties are separately found in various compounds reported for their anti-trypanosoma activities. In this work we evaluate the anti-T. cruzi activity of a collection of 26 "chimeric" molecules combining choroquinoline and amidine structures. In a first screening using epimastigote forms of the parasite as a proxy for the clinically relevant stages, we selected the compound 7-chloro-4-[4-(4,5-dihydro-1H-imidazol-2-yl)phenoxy]quinoline (named here as A6) that performed better as an anti-T. cruzi compound (IC50 of 2.2 ± 0.3 μM) and showed a low toxicity for the mammalian cell CHO-K1 (CC50 of 137.9 ± 17.3 μM). We initially investigated the mechanism of death associated to the selected compound. The A6 did not trigger phosphatidylserine exposure or plasma membrane permeabilization. Further investigation led us to observe that under short-term incubations (until 6 hours), no alterations of mitochondrial function were observed. However, at longer incubation times (4 days), A6 was able to decrease the intracellular Ca2+, to diminish the intracellular ATP levels, and to collapse mitochondrial inner membrane potential. After analysing the cell cycle, we found as well that A6 produced an arrest in the S phase that impairs the parasite proliferation. Finally, A6 was effective against the infective forms of the parasite during the infection of the mammalian host cells at a nanomolar concentration (IC50(tryps) = 26.7 ± 3.7 nM), exhibiting a selectivity index (SI) of 5,170. Our data suggest that A6 is a promising hit against T. cruzi.

Identification of a proteasome-targeting arylsulfonamide with potential for the treatment of Chagas' disease

Phenotypic screening identified an arylsulfonamide compound with activity against Trypanosoma cruzi, the causative agent of Chagas’ disease. Comprehensive mode of action studies revealed that this compound primarily targets the T. cruzi proteasome, binding at the interface between β4 and β5 subunits that catalyze chymotrypsin-like activity. A mutation in the β5 subunit of the proteasome was associated with resistance to compound 1, while overexpression of this mutated subunit also reduced susceptibility to compound 1. Further genetically engineered and in vitro-selected clones resistant to proteasome inhibitors known to bind at the β4/β5 interface were cross-resistant to compound 1. Ubiquitinated proteins were additionally found to accumulate in compound 1-treated epimastigotes. Finally, thermal proteome profiling identified malic enzyme as a secondary target of compound 1, although malic enzyme inhibition was not found to drive potency. These studies identify a novel pharmacophore capable of inhibiting the T. cruzi proteasome that may be exploitable for anti-chagasic drug discovery.

Development of new dinuclear Fe(III) coordination compounds with in vitro nanomolar antitrypanosomal activity

Chagas disease is a neglected tropical disease caused by the protozoan pathogen Trypanosoma cruzi. The disease is a major public health problem affecting about 6 to 7 million people worldwide, mostly in Latin America. The available therapy for this disease is based on two drugs, nifurtimox and benznidazole, which exhibit severe side effects, including resistance, severe cytotoxicity, variable efficacy and inefficiency in the chronic phase. Therefore, new drugs are urgently needed. Coordination compounds may be an interesting alternative for antiparasite therapy against Leishmania spp., Toxoplasma gondii and T. cruzi. Herein, we tested the in vitro effect on T. cruzi epimastigotes (Y strain) of two new μ-oxo Fe(III) dinuclear complexes: [(HL1)(Cl)Fe(μ-O)Fe(Cl)(HL2)](Cl)₂·(CH₃CH₂OH)₂·H₂O (1) and [(HL2)(Cl)Fe(μ-O)Fe(Cl)(HL2)](Cl)₂·H₂O (2) where HL1 and HL2 are ligands which contain two pyridines, amine and alcohol moieties with a naphthyl pendant unit yielding a N₃O coordination environment. Complexes (1) and (2), which are isomers, were completely characterized, including X-ray diffraction studies for complex (1). Parasites were treated with the complexes and the outcome was analyzed. Complex (1) exhibited the lowest IC₅₀ values, which were 99 ± 3, 97 ± 2 and 110 ± 39 nM, after 48, 72 and 120 h of treatment, respectively. Complex (2) showed IC₅₀ values of 118 ± 5, 122 ± 6 and 104 ± 29 nM for the same treatment times. Low cytotoxicity to the host cell LLC-MK2 was found for both complexes, resulting in impressive selectivity indexes of 106 for complex (1) and 178 for (2), after 120 h of treatment. Treatment with both complexes reduced the mitochondrial membrane potential of the parasite. Ultrastructural analysis of the parasite after treatment with complexes showed that the mitochondria outer membrane presented swelling and abnormal disposition around the kinetoplast; in addition, reservosomes presented anomalous spicules and rupture. The complexes showed low nanomolar IC₅₀ values affecting mitochondria and reservosomes, essential organelles for the survival of the parasite. The low IC₅₀ and the high selectivity index show that both complexes act as a new prototype of drugs against T. cruzi and may be used for further development in drug discovery to treat Chagas disease.

Why do few drug delivery systems to combat neglected tropical diseases reach the market? An analysis from the technology's stages

INTRODUCTION

Many drugs used to combat schistosomiasis, Chagas disease, and leishmaniasis (SCL) have clinical limitations such as: high toxicity to the liver, kidneys and spleen; reproductive, gastrointestinal, and heart disorders; teratogenicity. In this sense, drug delivery systems (DDSs) have been described in the literature as a viable option for overcoming the limitations of these drugs. An analysis of the level of development (TRL) of patents can help in determine the steps that must be taken for promising technologies to reach the market.

AREAS COVERED

This study aimed to analyze the stage of development of DDSs for the treatment of SCL described in patents. In addition, we try to understand the main reasons why many DDSs do not reach the market. In this study, we examined DDSs for drugs indicated by WHO and treatment of SCL, by performing a search for patents.

EXPERT OPINION

In this present work we provide arguments that support the hypothesis that there is a lack of integration between academia and industry to finance and continue research, especially the development of clinical studies. We cite the translational research consortia as the potential alternative for developing DDSs to combat NTDs.

The Chagas disease study landscape: A systematic review of clinical and observational antiparasitic treatment studies to assess the potential for establishing an individual participant-level data platform

Background

Chagas disease (CD), caused by the parasite Trypanosoma cruzi, affects ~6–7 million people worldwide. Significant limitations still exist in our understanding of CD. Harnessing individual participant data (IPD) from studies could support more in-depth analyses to address the many outstanding research questions. This systematic review aims to describe the characteristics and treatment practices of clinical studies in CD and assess the breadth and availability of research data for the potential establishment of a data-sharing platform.

Methodology/Principal findings

This review includes prospective CD clinical studies published after 1997 with patients receiving a trypanocidal treatment. The following electronic databases and clinical trial registry platforms were searched: Cochrane Library, PubMed, Embase, LILACS, Scielo, Clintrials.gov, and WHO ICTRP.

Of the 11,966 unique citations screened, 109 (0.9%) studies (31 observational and 78 interventional) representing 23,116 patients were included. Diagnosis for patient enrolment required 1 positive test result in 5 (4.6%) studies (2 used molecular method, 1 used molecular and serology, 2 used serology and parasitological methods), 2 in 60 (55.0%), 3 in 14 (12.8%) and 4 or more in 4 (3.7%) studies. A description of treatment regimen was available for 19,199 (83.1%) patients, of whom 14,605 (76.1%) received an active treatment and 4,594 (23.9%) were assigned to a placebo/no-treatment. Of the 14,605 patients who received an active treatment, benznidazole was administered in 12,467 (85.4%), nifurtimox in 825 (5.6%), itraconazole in 284 (1.9%), allopurinol in 251 (1.7%) and other drugs in 286 (1.9%). Assessment of efficacy varied largely and was based primarily on biological outcome; parasitological efficacy relied on serology in 67/85 (78.8%) studies, molecular methods in 52/85 (61.2%), parasitological in 34/85 (40.0%), microscopy in 3/85 (3.5%) and immunohistochemistry in 1/85 (1.2%). The median time at which parasitological assessment was carried out was 79 days [interquartile range (IQR): 30–180] for the first assessment, 180 days [IQR: 60–500] for second, and 270 days [IQR: 18–545] for the third assessment.

Conclusions/Significance

This review demonstrates the heterogeneity of clinical practice in CD treatment and in the conduct of clinical studies. The sheer volume of potential IPD identified demonstrates the potential for development of an IPD platform for CD and that such efforts would enable in-depth analyses to optimise the limited pharmacopoeia of CD and inform prospective data collection.

Chagas disease, also known as American trypanosomiasis, is a neglected tropical disease transmitted by triatomine insects, first identified in 1909. Chagas disease affects approximately 6–7 million people globally and is highly prevalent in Latin America where most cases are reported. However, there is increasing evidence that Chagas disease is now an important public health issue outside the “classical” endemic countries due to population migration. Our understanding of Chagas disease, including its pathologies and factors relating to progression, remains to date limited, and is also challenged by lack of diagnosis and highly effective treatment. This systematic review aims to describe studies with Chagas patients receiving antiparasitic treatment. Databases were searched for relevant studies published after 1997, and the results of these searches were screened.

Although a large volume of studies was identified in the review, heterogeneity was observed in study design, diagnostic methods, outcome assessment, and treatment regimens. While this aspect will be a limitation in pooling individual patient data, the volume of data available should allow sufficient comparison to form the basis of guidelines for future studies. The results of this review demonstrate that development of a Chagas disease data platform for clinical research would enable optimisation of existing data to strengthen evidence for the treatment and diagnosis of Chagas disease.

Nanotechnological interventions for treatment of trypanosomiasis in humans and animals

Trypanosomiasis is a parasitic infection caused by Trypanosoma. It is one of the major causes of deaths in underprivileged, rural areas of Africa, America and Asia. Depending on the parasite species responsible for the disease, it can take two forms namely African trypanosomiasis (sleeping sickness) and American trypanosomiasis (Chagas disease). The complete life-cycle stages of trypanosomes span between insect vector (tsetse fly, triatomine bug) and mammalian host (humans, animals). Only few drugs have been approved for the treatment of trypanosomiasis. Moreover, current trypanocidal therapy has major limitations of poor efficacy, serious side effects and drug resistance. Due to the lack of economic gains from tropical parasitic infection, it has always been neglected by the researchers and drug manufacturers. There is an immense need of more effective innovative strategies to decrease the deaths associated with this diseases. Nanotechnological approaches for delivery of existing drugs have shown significant improvement in efficacy with many-fold decrease in their dose. The review emphasizes on nanotechnological interventions in the treatment of trypanosomiasis in both humans and animals. Current trypanocidal therapy and their limitations have also been discussed briefly. Graphical abstract.

Fibronectin degradation as biomarker for Trypanosoma cruzi infection and treatment monitoring in mice

Biomarkers (coming from host or parasite) to monitor Chagas disease (CD) progression as well as the therapeutic response in chronic CD are critically needed, since seronegativization, which may be considered the best indicator of therapeutic cure, takes several years to be observed in adults. Several molecules have been suggested as biomarkers for CD, however, they have to be validated. Taking advantage of mouse models of Trypanosoma cruzi infection, we investigated changes in the degradation profile of fibronectin in plasma. The degradation profile of fibronectin was different in the acute phase compared to the chronic phase of the infection. Fibronectin fragments of approximately 150, 100, 40 and 30 kDa were identified. Furthermore, those degradation profiles correlated with acute parasitaemia as well as with cardiac parasite burden and tissue damage during the infection. The usefulness of fibronectin degradation as a biomarker for therapeutic response following drug treatment and immunotherapeutic vaccination also was evaluated and a decreased fibronectin degradation profile was observed upon benznidazole or a vaccine candidate treatment.

Benznidazole Treatment: Time- and Dose-Dependence Varies with the Trypanosoma cruzi Strain

As the development of new drugs for Chagas disease is not a priority due to its neglected disease status, an option for increasing treatment adherence is to explore alternative treatment regimens, which may decrease the incidence of side effects. Therefore, we evaluated the efficacy of different therapeutic schemes with benznidazole (BNZ) on the acute and chronic phases of the disease, using mice infected with strains that have different BNZ susceptibilities. Our results show that the groups of animals infected by VL-10 strain, when treated in the chronic phase with a lower dose of BNZ for a longer period of time (40 mg/kg/day for 40 days) presented better treatment efficacy than with the standard protocol (100 mg/kg/day for 20 days) although the best result in the treatment of the animals infected by the VL-10 strain was with100 mg/kg/day for 40 days. In the acute infection by the Y and VL-10 strains of T. cruzi, the treatment with a standard dose, but with a longer time of treatment (100 mg/kg/day for 40 days) presented the best results. Given these data, our results indicate that for BNZ, the theory of dose and time proportionality does not apply to the phases of infection.

Diet Rich in Lard Promotes a Metabolic Environment Favorable to Trypanosoma cruzi Growth

Background: Trypanosoma cruzi is a protozoan parasite that causes Chagas disease and affects 6-7 million people mainly in Latin America and worldwide. Here, we investigated the effects of hyperlipidic diets, mainly composed of olive oil or lard on experimental T. cruzi infection. C57BL/6 mice were fed two different dietary types in which the main sources of fatty acids were either monounsaturated (olive oil diet) or saturated (lard diet). Methods: After 60 days on the diet, mice were infected with 50 trypomastigote forms of T. cruzi Colombian strain. We evaluated the systemic and tissue parasitism, tissue inflammation, and the redox status of mice after 30 days of infection. Results: Lipid levels in the liver of mice fed with the lard diet increased compared with that of the mice fed with olive oil or normolipidic diets. The lard diet group presented with an increased parasitic load in the heart and adipose tissues following infection as well as an increased expression of Tlr2 and Tlr9 in the heart. However, no changes were seen in the survival rates across the dietary groups. Infected mice receiving all diets presented comparable levels of recruited inflammatory cells at 30 days post-infection but, at this time, we observed lard diet inducing an overproduction of CCL2 in the cardiac tissue and its inhibition in the adipose tissue. T. cruzi infection altered liver antioxidant levels in mice, with the lard diet group demonstrating decreased catalase (CAT) activity compared with that of other dietary groups. Conclusions: Our data demonstrated that T. cruzi growth is more favorable on tissue of mice subjected to the lard diet. Our findings supported our hypothesis of a relationship between the source of dietary lipids and parasite-induced immunopathology.

Tambjamines and Prodiginines: Biocidal Activity against Trypanosoma cruzi

The aim of this work was to explore new therapeutic options against Chagas disease by the in vitro analysis of the biocidal activities of several tambjamine and prodiginine derivatives, against the Trypanosoma cruzi CLB strain (DTU TcVI). The compounds were initially screened against epimastigotes. The five more active compounds were assayed in intracellular forms. The tambjamine MM3 and both synthetic and natural prodigiosins displayed the highest trypanocidal profiles, with IC₅₀ values of 4.52, 0.46, and 0.54 µM for epimastigotes and 1.9, 0.57, and 0.1 µM for trypomastigotes/amastigotes, respectively. Moreover, the combination treatment of these molecules with benznidazole showed no synergism. Finally, oxygen consumption inhibition determinations performed using high-resolution respirometry, revealed a potent effect of prodigiosin on parasite respiration (73% of inhibition at ½ IC₅₀), suggesting that its mode of action involves the mitochondria. Moreover, its promising selectivity index (50) pointed out an interesting trypanocidal potential and highlighted the value of prodigiosin as a new candidate to fight Chagas disease.

Combination With Tomatidine Improves the Potency of Posaconazole Against Trypanosoma cruzi

Azoles such as posaconazole (Posa) are highly potent against Trypanosoma cruzi. However, when tested in chronic Chagas disease patients, a high rate of relapse after Posa treatment was observed. It appears that inhibition of T. cruzi cytochrome CYP51, the target of azoles, does not deliver sterile cure in monotherapy. Looking for suitable combination partners of azoles, we have selected a set of inhibitors of sterol and sphingolipid biosynthetic enzymes. A small-scale phenotypic screening was conducted in vitro against the proliferative forms of T. cruzi, extracellular epimastigotes and intracellular amastigotes. Against the intracellular, clinically relevant forms, four out of 15 tested compounds presented higher or equal activity as benznidazole (Bz), with EC₅₀ values ≤2.2 μM. Ro48-8071, an inhibitor of lanosterol synthase (ERG7), and the steroidal alkaloid tomatidine (TH), an inhibitor of C-24 sterol methyltransferase (ERG6), exhibited the highest potency and selectivity indices (SI = 12 and 115, respectively). Both were directed to combinatory assays using fixed-ratio protocols with Posa, Bz, and fexinidazole. The combination of TH with Posa displayed a synergistic profile against amastigotes, with a mean ΣFICI value of 0.2. In vivo assays using an acute mouse model of T. cruzi infection demonstrated lack of antiparasitic activity of TH alone in doses ranging from 0.5 to 5 mg/kg. As observed in vitro, the best combo proportion in vivo was the ratio 3 TH:1 Posa. The combination of Posa at 1.25 mpk plus TH at 3.75 mpk displayed suppression of peak parasitemia of 80% and a survival rate of 60% in the acute infection model, as compared to 20% survival for Posa at 1.25 mpk alone and 40% for Posa at 10 mpk alone. These initial results indicate a potential for the combination of posaconazole with tomatidine against T. cruzi.

Vaccine-linked chemotherapy induces IL-17 production and reduces cardiac pathology during acute Trypanosoma cruzi infection

Chagas disease resulting from Trypanosoma cruzi infection leads to a silent, long-lasting chronic neglected tropical disease affecting the poorest and underserved populations around the world. Antiparasitic treatment with benznidazole does not prevent disease progression or death in patients with established cardiac disease. Our consortium is developing a therapeutic vaccine based on the T. cruzi flagellar—derived antigen Tc24-C4 formulated with a Toll-like receptor 4 agonist adjuvant, to complement existing chemotherapy and improve treatment efficacy. Here we demonstrate that therapeutic treatment of acutely infected mice with a reduced dose of benznidazole concurrently with vaccine treatment – also known as “vaccine-linked chemotherapy”—induced a T_H17 like immune response, with significantly increased production of antigen specific IL-17A, IL-23 and IL-22, and CD8 + T lymphocytes, as well as significantly increased T. cruzi specific IFNγ-producing CD4 + T lymphocytes. Significantly reduced cardiac inflammation, fibrosis, and parasite burdens and improved survival were achieved by vaccine-linked chemotherapy and individual treatments. Importantly, low dose treatments were comparably efficacious to high dose treatments, demonstrating potential dose sparing effects. We conclude that through induction of T_H17 immune responses vaccine-linked chemotherapeutic strategies could bridge the tolerability and efficacy gaps of current drug treatment in Chagasic patients.

Development and characterization of thermopressed polyvinyl alcohol films for buccal delivery of benznidazole

Given that oral preparations of benznidazole (BZN) have demonstrated limited efficacy in the treatment of Chagas' disease due to pharmacokinetic or toxicological problems, the development of buccal polymeric films was purposed in this study. These systems ensure high patient acceptability and direct access to the systemic circulation, improving drug bioavailability and toxicological profile. Polymer films were prepared through a thermopressing method by mixing BZN and polyvinyl alcohol (PVAL). In some preparations, propylene glycol (PG) and thymol (TM) were also included as plasticizer and chemical absorption enhancer, respectively. Morphology, X-ray diffraction, spectroscopic, thermal, mechanical, and water uptake properties, as well as ex vivo permeability studies, were performed to characterize the film formulations. BZN remained stable and in an amorphous form over 90 days. The addition of PG and TM improved the mechanical properties of the films, making them soft, flexible and tear-resistant. Also, these additives increased the water sorption rate of the films at 50 and 75% relative humidity and the TM increased the film erosion properties and drug permeability (close to 6×) compared to control. It was hypothesized that the permeability improvement of thymol-based films that follow a drug release profile through erosion is also associated with the inhibition of the crystallization of BNZ when the film is in contact with the buccal mucosa. Once the thymol has previously demonstrated a significant in vivo and in vitro trypanocidal action and even improved film characteristics, these systems may be considered promising for Chagas' disease treatment.

Chagas Disease: Current View of an Ancient and Global Chemotherapy Challenge

Chagas disease is a neglected tropical disease and a global public health issue. In terms of treatment, no progress has been made since the 1960s, when benznidazole and nifurtimox, two obsolete drugs still prescribed, were used to treat this disease. Hence, currently, there are no effective treatments available to tackle Chagas disease. Over the past 20 years, there has been an increasing interest in the disease. However, parasite genetic diversity, drug resistance, tropism, and complex life cycle, along with the limited understanding of the disease and inadequate methodologies and strategies, have resulted in the absence of new insights in drugs development and disappointing outcomes in clinical trials so far. In summary, new drugs are urgently needed. This Review considers the relevant aspects related to the lack of drugs for Chagas disease, resumes the advances in tools for drug discovery, and discusses the main features to be taken into account to develop new effective drugs.

A novel Trypanosoma cruzi secreted antigen as a potential biomarker of Chagas disease

Chagas drug discovery has been hampered by a lack of validated assays to establish treatment efficacy in pre-clinical animal models and in patients infected with T. cruzi. Reduced levels of parasite secreted antigens in the blood of infected hosts could be used to demonstrate treatment efficacy. A published proteomic study of parasite secreted antigens identified the hypothetical protein Tc_5171 as a secreted antigen. In this report, we developed Tc_5171 specific antibodies and showed that the native protein was expressed by the three life cycle stages of the parasite. Anti-peptide antibodies were able to detect the parasite antigen in blood of infected mice during the acute and the chronic phase of infection. Benznidazole treatment of infected mice significantly reduced their blood antigen levels. Of clinical significance, patients diagnosed with Chagas disease, either asymptomatic or with cardiac clinical symptoms had significantly higher Tc_5171 antigen levels compared to endemic controls. Pair-wise analysis, before and after Benznidazole treatment, of patients with asymptomatic Chagas disease showed a significant reduction in antigen levels post treatment. Taken together, our results indicate that Tc_5171 could be used as a novel biomarker of Chagas disease for diagnosis and to assess treatment efficacy.

Benznidazole for the treatment of Chagas disease

INTRODUCTION

Chagas disease affects 6-7 million people, mainly in the Americas, and benznidazole is one of the two therapeutic options available. Trypanocide treatment aims to eliminate the parasite from the body to prevent the establishment or progression of visceral damage, mainly cardiac and/or digestive. Remarkably, it helps interrupt vertical transmission when administered to women of childbearing age.

AREAS COVERED

We discuss the basic and scarce data regarding chemical, pharmacokinetic, and pharmacodynamic structure. We also collect the most important data from previous phase II and III studies, as well as studies currently underway and upcoming. We reflect on the main indications for treatment and its challenges, such as the profile of adverse effects in adults, the pharmaceutical formulations, the search for reliable biomarkers, as well as regulatory aspects and access barriers. Alternative strategies such as shorter regimens, lower doses, and fixed doses are currently being evaluated to improve access and the safety profile of this treatment.

EXPERT OPINION

Benznidazole is likely to continue to be the drug of choice for Chagas disease in the coming years. However, it would probably be with a different treatment scheme.

Cruzipain and Its Physiological Inhibitor, Chagasin, as a DNA-Based Therapeutic Vaccine Against Trypanosoma cruzi

Chagas disease caused by the protozoan parasite Trypanosoma cruzi is endemic in 21 Latin American countries and the southern United States and now is spreading into several other countries due to migration. Despite the efforts to control the vector throughout the Americas, currently, there are almost seven million infected people worldwide, causing ~10,000 deaths per year, and 70 million people at risk to acquire the infection. Chagas disease treatment is restricted only to two parasiticidal drugs, benznidazole and nifurtimox, which are effective during the acute and early infections but have not been found to be as effective in chronic infection. No prophylactic or therapeutic vaccine for human use has been communicated at this moment. Here, we evaluate in a mouse model a therapeutic DNA vaccine combining Cruzipain (Cz), a T. cruzi cysteine protease that proved to be protective in several settings, and Chagasin (Chg), which is the natural Cz inhibitor. The DNAs of both antigens, as well as a plasmid encoding GM-CSF as adjuvant, were orally administrated and delivered by an attenuated Salmonella strain to treat mice during the acute phase of T. cruzi infection. The bicomponent vaccine based on Salmonella carrying Cz and Chg (SChg+SCz) was able to improve the protection obtained by each antigen as monocomponent therapeutic vaccine and significantly increased the titers of antigen- and parasite-specific antibodies. More importantly, the bicomponent vaccine triggered a robust cellular response with interferon gamma (IFN-γ) secretion that rapidly reduced the parasitemia during the acute phase and decreased the tissue damage in the chronic stage of the infection, suggesting it could be an effective tool to ameliorate the pathology associated to Chagas disease.

Trypanocidal treatment of Chagas disease

Chagas disease is a neglected parasitosis caused by the protozoan parasite Trypanosoma cruzi. This infection is present in most Latin American countries, although, due to migratory movements, it is a growing cause for concern in non-endemic countries. The only two drugs currently available for its treatment-benznidazole and nifurtimox-were marketed 50 years ago. While they are very effective for acute and recent infection, and for the prevention of maternofoetal transmission, their efficacy declines in people who have chronic infection, especially those older than 18 years of age. In the presence of visceral involvement, parasiticidal treatment is of little or no value. The safety profile of both drugs is far from ideal, with frequent adverse events and high rates of drug discontinuation, mainly in adults. So far, new drugs and new strategies have not been shown to improve the results of the current nitroimidazoles, although the results are promising. In this review, we focus on the aspects that allow clinicians to make the best use of currently available drugs. In addition, we discuss new therapeutic options and ongoing research in the field.

Bisphosphonate-Based Molecules as Potential New Antiparasitic Drugs

Neglected tropical diseases such as Chagas disease and leishmaniasis affect millions of people around the world. Both diseases affect various parts of the globe and drugs traditionally used in therapy against these diseases have limitations, especially with regard to low efficacy and high toxicity. In this context, the class of bisphosphonate-based compounds has made significant advances regarding the chemical synthesis process as well as the pharmacological properties attributed to these compounds. Among this spectrum of pharmacological activity, bisphosphonate compounds with antiparasitic activity stand out, especially in the treatment of Chagas disease and leishmaniasis caused by Trypanosoma cruzi and Leishmania spp., respectively. Some bisphosphonate compounds can inhibit the mevalonate pathway, an essential metabolic pathway, by interfering with the synthesis of ergosterol, a sterol responsible for the growth and viability of these parasites. Therefore, this review aims to present the information about the importance of these compounds as antiparasitic agents and as potential new drugs to treat Chagas disease and leishmaniasis.

Development of a High-Throughput Screening Assay to Identify Inhibitors of the Major M17-Leucyl Aminopeptidase from Trypanosoma cruzi Using RapidFire Mass Spectrometry

Leucyl aminopeptidases (LAPs) are involved in multiple cellular functions, which, in the case of infectious diseases, includes participation in the pathogen-host cell interface and pathogenesis. Thus, LAPs are considered good candidate drug targets, and the major M17-LAP from Trypanosoma cruzi (LAPTc) in particular is a promising target for Chagas disease. To exploit LAPTc as a potential target, it is essential to develop potent and selective inhibitors. To achieve this, we report a high-throughput screening method for LAPTc. Two methods were developed and optimized: a Leu-7-amido-4-methylcoumarin-based fluorogenic assay and a RapidFire mass spectrometry (RapidFire MS)-based assay using the LSTVIVR peptide as substrate. Compared with a fluorescence assay, the major advantages of the RapidFire MS assay are a greater signal-to-noise ratio as well as decreased consumption of enzyme. RapidFire MS was validated with the broad-spectrum LAP inhibitors bestatin (IC₅₀ = 0.35 μM) and arphamenine A (IC₅₀ = 15.75 μM). We suggest that RapidFire MS is highly suitable for screening for specific LAPTc inhibitors.

Catalytic mechanism and properties of pyridoxal 5'-phosphate independent racemases: how enzymes alter mismatched acidity and basicity

Covering: up to March 2019 Amino acid racemases and epimerases are key enzymes that invert the configuration of common amino acids and supply many corresponding d-isomers in living organisms. Some d-amino acids are inherently bioactive, whereas others are building blocks for important biomolecules, for example lipid II, the bacterial cell wall precursor. Peptides containing them have enhanced proteolytic stability and can act as important recognition elements in mammalian systems. Selective inhibition of certain amino acid racemases (e.g. glutamate racemase) is believed to offer a promising target for new antibacterial drugs effective against pathogens resistant to current antibiotics. Many amino acid racemases employ imine formation with pyridoxal phosphate (PLP) as a cofactor to accelerate the abstraction of the alpha proton. However, the group reviewed herein achieves racemization of free amino acids without the use of cofactors or metals, and uses a thiol/thiolate pair for deprotonation and reprotonation. All bacteria and higher plants contain such enzymes, for example diaminopimelate epimerase, which is required for lysine biosynthesis in these organisms. This process cannot be accomplished without an enzyme catalyst as the acidities of a thiol and the substrate α-hydrogen are inherently mismatched by at least 10 orders of magnitude. This review describes the structural and mechanistic studies on PLP-independent racemases and the evolving view of key enzymatic machinery that accomplishes these remarkable transformations.

Efficacy and safety assessment of different dosage of benznidazol for the treatment of Chagas disease in chronic phase in adults (MULTIBENZ study): study protocol for a multicenter randomized Phase II non-inferiority clinical trial

BACKGROUND

Chagas disease (CD) continues to be a neglected infectious disease with one of the largest burdens globally. Despite the modest cure rates in adult chronic patients and its safety profile, benznidazole (BNZ) is still the drug of choice. Its current recommended dose is based on nonrandomized studies, and efficacy and safety of the optimal dose of BNZ have been scarcely analyzed in clinical trials.

METHODS/DESIGN

MULTIBENZ is a phase II, randomized, noninferiority, double-blind, multicenter international clinical trial. A total of 240 patients with Trypanosoma CD in the chronic phase will be recruited in four different countries (Argentina, Brazil, Colombia, and Spain). Patients will be randomized to receive BNZ 150 mg/day for 60 days, 400 mg/day for 15 days, or 300 mg/day for 60 days (comparator arm). The primary outcome is the efficacy of three different BNZ therapeutic schemes in terms of dose and duration. Efficacy will be assessed according to the proportion of patients with sustained parasitic load suppression in peripheral blood measured by polymerase chain reaction. The secondary outcomes are related to pharmacokinetics and drug tolerability. The follow-up will be 12 months from randomization to end of study participation. Recruitment was started in April 2018.

CONCLUSION

This is a clinical trial conducted for the assessment of different dose schemes of BNZ compared with the standard treatment regimen for the treatment of CD in the chronic phase. MULTIBENZ may help to clarify which is the most adequate BNZ regimen in terms of efficacy and safety, predicated on sustained parasitic load suppression in peripheral blood.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03191162. Registered on 19 June 2017.

Discovery of Potent N-Ethylurea Pyrazole Derivatives as Dual Inhibitors of Trypanosoma brucei and Trypanosoma cruzi

Trypanosoma brucei (T. brucei) and Trypanosoma cruzi (T. cruzi) are causative agents of parasitic diseases known as human African trypanosomiasis and Chagas disease, respectively. Together, these diseases affect 68 million people around the world. Current treatments are unsatisfactory, frequently associated with intolerable side-effects, and generally inadequate in treating all stages of disease. In this paper, we report the discovery of N-ethylurea pyrazoles that potently and selectively inhibit the viability of T. brucei and T. cruzi. Sharp and logical SAR led to the identification of 54 as the best compound, with an in vitro IC₅₀ of 9 nM and 16 nM against T. b. brucei and T. cruzi, respectively. Compound 54 demonstrates favorable physicochemical properties and was efficacious in a murine model of Chagas disease, leading to undetectable parasitemia within 6 days when CYP metabolism was inhibited.

Human acute Chagas disease: changes in factor VII, activated protein C and hepatic enzymes from patients of oral outbreaks in Pará State (Brazilian Amazon)

Oral transmission of Chagas disease has been increasing in Latin American countries. The present study aimed to investigate changes in hepatic function, coagulation factor levels and parasite load in human acute Chagas disease (ACD) secondary to oral Trypanosoma cruzi transmission. Clinical and epidemiological findings of 102 infected individuals attended in the State of Pará from October 2013 to February 2016 were included. The most common symptoms were fever (98%), asthenia (83.3%), face and limb edema (80.4%), headache (74.5%) and myalgia (72.5%). The hepatic enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) of 30 ACD patients were higher compared with controls, and this increase was independent of the treatment with benznidazole. Moreover, ACD individuals had higher plasma levels of activated protein C and lower levels of factor VII of the coagulation cascade. Patients with the highest parasite load had also the most increased transaminase levels. Also, ALT and AST were associated moderately (r = 0.429) and strongly (r = 0.595) with parasite load respectively. In conclusion, the present study raises the possibility that a disturbance in coagulation and hepatic function may be linked to human ACD.

Transbuccal delivery of benznidazole associated with monoterpenes: permeation studies and mechanistic insights

Benznidazole (BZN) represents the only drug currently available for the treatment of Chagas disease in most endemic countries. When administered orally, high doses are required due to its extensive hepatic metabolism and its toxicity represents the main reason for treatment withdrawals. Because of these complications, transbuccal administration of BZN was investigated. This route avoids the first-pass hepatic metabolism and presents high permeability, with direct access to the systemic circulation. BZN was applied on porcine buccal mucosa after pretreatment with pure eugenol, carvacrol or limonene. Thermal (DSC) and spectroscopic (FT-IR) analyzes were performed to investigate the mechanisms of drug absorption enhancement. The permeability coefficient values of BZN increased 2.6, 2.9 and 4.9-fold after pretreatment with eugenol, carvacrol and limonene, respectively. The lag time, in turn, was shortened in the pretreated samples. The DSC and FT-IR analyzes suggested that transport of BZN through the buccal mucosa is associated with log P and size of monoterpenes. Limonene, the most effective absorption enhancer, contributed to greater interaction with non-polar domains of the buccal epithelium. Overall, BZN showed to be efficiently transported through the buccal route, but in vivo pharmacokinetic studies should be performed to confirm these findings.

Usefulness of real-time PCR during follow-up of patients treated with Benznidazole for chronic Chagas disease: Experience in two referral centers in Barcelona

BACKGROUND

Antitrypanosomal treatment with Benznidazole (BZ) or Nifurtimox may be recommended for patients with chronic Chagas disease (CD) to reduce the onset or progression of symptoms. However, such treatment has limited efficacy and high level of toxic effects. In addition, the current cure biomarker (serology conversion) precludes any treatment assessment unless a prolonged follow-up is arranged. PCR is thus the most useful, alternative surrogate marker for evaluating responses to treatment. The aim of this study is to describe the usefulness of real-time PCR in monitoring BZ treatment within a large cohort of chronic CD cases in Barcelona.

METHODOLOGY/PRINCIPAL FINDINGS

A total of 370 chronic CD patients were monitored with real-time PCR post-BZ treatment. The median follow-up was 4 years (IQR 2.2-5.3y), with a median of 3 clinical visits (IQR 2-4). Only 8 patients (2.2%) presented with at least one incident of positive real-time PCR after treatment and were therefore considered as treatment failure. Four of those failure patients had completed full course treatment, whereas the remaining cases had defaulted with a statistical difference between both groups (p = 0.02). Half of the failure patients had undergone less than 4 years of follow-up monitoring all presented with parasitemia before treatment.

CONCLUSIONS/SIGNIFICANCE

BZ treatment failure was highly infrequent in our cohort. BZ discontinuation was a risk factor for positive real-time PCR results during clinical follow-up. Regular testing with real-time PCR during follow-up allows for early detection of treatment failure in patients with chronic CD.

Does Progressive Introduction of Benznidazole Reduce the Chance of Adverse Events in the Treatment of Chagas Disease?

In this retrospective cohort study, we aimed to assess whether introducing benznidazole at escalating doses reduces the probability of adverse events or treatment discontinuation compared with a full-dose scheme. We collected data from patients who had chronic Trypanosoma cruzi infection and underwent treatment from July 2008 to January 2017 in a referral center in Madrid. Dose was adjusted to body weight (5 mg/kg/day), with treatment introduction with full dose or escalating dose according to local consensus and protocols. Among the 62 patients treated, benznidazole was introduced at full dose in 28 patients and on escalating dose in the remaining 34. We found no statistical differences in the number of adverse events, treatment discontinuations, days of treatment, or sociodemographic profiles. There is insufficient evidence to support escalating dose as a strategy for reducing the adverse effects of benznidazole. Further research is needed to evaluate this approach.

Low-dose of benznidazole promotes therapeutic cure in experimental chronic Chagas' disease with absence of parasitism in blood, heart and colon

Studies suggest that the dose of the standard benznidazole (BNZ) treatment regimen might be too high. We investigated the efficacy of BNZ 20 and 40 mg/kg/day compared with standard dose (100 mg/kg/day) to induce cure in mice infected with Trypanosoma cruzi Y strain in the acute and chronic phases of Chagas' disease. Our findings indicate that an experimental treatment with a BNZ low-dose (40 mg/kg/day) is similarly effective as the usual dose in the chronic mice model (100% of cure). In addition, the treatment in the chronic model of Chagas' disease presented better results than the acute model and colon appears to be a key tissue when it comes to evaluating treatment efficacy compared to blood and heart. Therefore, our data suggest the reconsideration of the current therapy, mainly in the chronic phase of the disease.

The Thiol-polyamine Metabolism of Trypanosoma cruzi: Molecular Targets and Drug Repurposing Strategies

Chagas´ disease continues to be a challenging and neglected public health problem in many American countries. The etiologic agent, Trypanosoma cruzi, develops intracellularly in the mammalian host, which hinders treatment efficacy. Progress in the knowledge of parasite biology and host-pathogen interaction has not been paralleled by the development of novel, safe and effective therapeutic options. It is then urgent to seek for novel therapeutic candidates and to implement drug discovery strategies that may accelerate the discovery process. The most appealing targets for pharmacological intervention are those essential for the pathogen and, whenever possible, absent or significantly different from the host homolog. The thiol-polyamine metabolism of T. cruzi offers interesting candidates for a rational design of selective drugs. In this respect, here we critically review the state of the art of the thiolpolyamine metabolism of T. cruzi and the pharmacological potential of its components. On the other hand, drug repurposing emerged as a valid strategy to identify new biological activities for drugs in clinical use, while significantly shortening the long time and high cost associated with de novo drug discovery approaches. Thus, we also discuss the different drug repurposing strategies available with a special emphasis in their applications to the identification of drug candidates targeting essential components of the thiol-polyamine metabolism of T. cruzi.

Structure of Urocanate Hydratase from the protozoan Trypanosoma cruzi

The enzyme Urocanate Hydratase (UH) participates in the catabolic pathway of L-histidine. Trypanosoma cruzi Urocanate Hydratase (TcUH) is identified as a therapeutic molecular target in the WHO/TDR Targets Database. We report the 3D structure determination and number of features of TcUH, and compared it to other few available bacterial UH structures. Each monomer presents two domains and one NAD⁺ molecule. Superpositions revealed differences in the relative orientation of domains within monomers, such that TcUH monomer A resembles Urocanate Hydratase from Geobacillus kaustophilus (GkUH) (open conformation), while monomer C resembles Urocanate Hydratase from Pseudomonas putida (PpUH) and Urocanate Hydratase from Bacillus subtilis (BsUH) (closed conformations). We use the structure of TcUH to make considerations about 3 non-deleterious and 2 deleterious mutations found in human UHs: non-deleterious mutations could be accommodated without large displacements or interaction interruptions, whereas deleterious mutations in one case might disrupt an α-helix (as previously suggested) and in the other case, besides disrupting the enzyme interaction with the substrate, might interfere with interdomain movement.

Structure-Based and Molecular Modeling Studies for the Discovery of Cyclic Imides as Reversible Cruzain Inhibitors With Potent Anti-Trypanosoma cruzi Activity

Chagas disease causes ~10,000 deaths each year, mainly in Latin America, where it is endemic. The currently available chemotherapeutic agents are ineffective in the chronic stage of the disease, and the lack of pharmaceutical innovation for Chagas disease highlights the urgent need for the development of new drugs. The enzyme cruzain, the main cysteine protease of Trypanosoma cruzi, has been explored as a validated molecular target for drug discovery. Herein, the design, molecular modeling studies, synthesis, and biological evaluation of cyclic imides as cruzain inhibitors are described. Starting with a micromolar-range cruzain inhibitor (3a, IC₅₀ = 2.2 μM), this molecular optimization strategy resulted in the nanomolar-range inhibitor 10j (IC₅₀ = 0.6 μM), which is highly active against T. cruzi intracellular amastigotes (IC₅₀ = 1.0 μM). Moreover, most compounds were selective toward T. cruzi over human fibroblasts, which were used as host cells, and are less toxic to hepatic cells than the marketed drug benznidazole. This study enabled the discovery of novel chemical diversity and established robust structure-activity relationships to guide the design of optimized cruzain inhibitors as new trypanocidal agents.

A case report of long treatment with Itraconazole in a patient with chronic Chagas disease

Background

Current available treatments (benznidazole and nifurtimox) for Chagas disease (CD) show limited efficacy in chronic phase and frequent undesirable effects. Ergosterol synthesis inhibitors (ESI) had been considered as promising drugs for CD treatment and despite its recent poor results in several clinical trials, different strategies have been proposed to optimize its role in this infection.

Case presentation

We present a case of chronic Chagas disease in patient diagnosed with HIV who received treatment for histoplasmosis with itraconazol during twelve months. Even though T. cruzi rt-PCR was persistently negative during treatment, when itraconazol was stopped she presented with a positive blood rt-PCR.

Conclusion

Several studies using different ESI had been published for CD treatment. Either in vitro or in vivo assays demonstrated activity against T. cruzi of the different triazole derivatives so different clinical trials had been carried out to evaluate its efficacy and safety. Despite contradictory evidence in the animal model, longer treatments along with other treatment strategies previously proposed suggests that ESI failure rates in positive peripheral blood rt-PCR are higher than that obtained with the current treatments of choice.