Benznidazole-related adverse drug reactions and their relationship to serum drug concentrations in patients with chronic chagas disease

Nanomedicines against Chagas disease: a critical review

Chagas disease (CD) is the most important endemic parasitosis in South America and represents a great socioeconomic burden for the chronically ill and their families. The only currently available treatment against CD is based on the oral administration of benznidazole, an agent, developed in 1971, of controversial effectiveness on chronically ill patients and toxic to adults. So far, conventional pharmacological approaches have failed to offer more effective and less toxic alternatives to benznidazole. Nanomedicines reduce toxicity and increase the effectiveness of current oncological therapies. Could nanomedicines improve the treatment of the neglected CD? This question will be addressed in this review, first by critically discussing selected reports on the performance of benznidazole and other molecules formulated as nanomedicines in in vitro and in vivo CD models. Taking into consideration the developmental barriers for nanomedicines and the degree of current technical preclinical efforts, a prospect of developing nanomedicines against CD will be provided. Not surprisingly, we conclude that structurally simpler formulations with minimal production cost, such as oral nanocrystals and/or parenteral nano-immunostimulants, have the highest chances of making it to the market to treat CD. Nonetheless, substantive political and economic decisions, key to facing technological challenges, are still required regarding a realistic use of nanomedicines effective against CD.

Targeting Cysteine Proteases and their Inhibitors to Combat Trypanosomiasis

BACKGROUND

Trypanosomiasis, caused by protozoan parasites of the Trypanosoma genus, remains a significant health burden in several regions of the world. Cysteine proteases play a crucial role in the pathogenesis of Trypanosoma parasites and have emerged as potential therapeutic targets for the development of novel antiparasitic drugs.

INTRODUCTION

This review article aims to provide a comprehensive overview of the role of cysteine proteases in trypanosomiasis and their potential as therapeutic targets. We discuss the biological significance of cysteine proteases in Trypanosoma parasites and their involvement in essential processes, such as host immune evasion, cell invasion, and nutrient acquisition.

METHODS

A comprehensive literature search was conducted to identify relevant studies and research articles on the role of cysteine proteases and their inhibitors in trypanosomiasis. The selected studies were critically analyzed to extract key findings and provide a comprehensive overview of the topic.

RESULTS

Cysteine proteases, such as cruzipain, TbCatB and TbCatL, have been identified as promising therapeutic targets due to their essential roles in Trypanosoma pathogenesis. Several small molecule inhibitors and peptidomimetics have been developed to target these proteases and have shown promising activity in preclinical studies.

CONCLUSION

Targeting cysteine proteases and their inhibitors holds great potential for the development of novel antiparasitic drugs against trypanosomiasis. The identification of potent and selective cysteine protease inhibitors could significantly contribute to the combat against trypanosomiasis and improve the prospects for the treatment of this neglected tropical disease.

Clinical trials for Chagas disease: etiological and pathophysiological treatment

Chagas disease (CD) is caused by the flagellate protozoan Trypanosoma cruzi. It is endemic in Latin America. Nowadays around 6 million people are affected worldwide, and 75 million are still at risk. CD has two evolutive phases, acute and chronic. The acute phase is mostly asymptomatic, or presenting unspecific symptoms which makes it hard to diagnose. At the chronic phase, patients can stay in the indeterminate form or develop cardiac and/or digestive manifestations. The two trypanocide drugs available for the treatment of CD are benznidazole (BZ) and nifurtimox (NFX), introduced in the clinic more than five decades ago. WHO recommends treatment for patients at the acute phase, at risk of congenital infection, for immunosuppressed patients and children with chronic infection. A high cure rate is seen at the CD acute phase but better treatment schemes still need to be investigated for the chronic phase. There are some limitations within the use of the trypanocide drugs, with side effects occurring in about 40% of the patients, that can lead patients to interrupt treatment. In addition, patients with advanced heart problems should not be treated with BZ. This is a neglected disease, discovered 114 years ago that still has no drug effective for their chronic phase. Multiple social economic and cultural barriers influence CD research. The high cost of the development of new drugs, in addition to the low economical return, results in the lack of investment. More economic support is required from governments and pharmaceutical companies on the development of more research for CD treatment. Two approaches stand out: repositioning and combination of drugs, witch drastically decrease the cost of this process, when compared to the development of a new drug. Here we discuss the progress of the clinical trials for the etiological and pathophysiological treatment for CD. In summary, more studies are needed to propose a new drug for CD. Therefore, BZ is still the best option for CD. The trials in course should clarify more about new treatment regimens, but it is already possible to indicate that dosage and time of treatment need to be adjusted.

Trypanosoma cruzi Secreted Cyclophilin TcCyP19 as an Early Marker for Trypanocidal Treatment Efficiency

Cyclophilins (CyPs) are a family of enzymes involved in protein folding. Trypanosoma cruzi, the causative agent of Chagas disease, has a 19-kDa cyclophilin, TcCyP19, that was found to be secreted in parasite stages of the CL Brener clone and recognized by sera from T. cruzi-infected mice and patients. The levels of specific antibodies against TcCyP19 in T. cruzi-infected mice and subjects before and after drug treatment were measured by an in-house enzyme linked immunosorbent assay (ELISA). Mice in the acute and chronic phase of infection, with successful trypanocidal treatments, showed significantly lower anti-TcCyP19 antibody levels than untreated mice. In children and adults chronically infected with T. cruzi, a significant decrease in the anti-TcCyP19 titers was observed after 12 months of etiological treatment. This decrease was maintained in adult chronic patients followed-up 30-38 months post-treatment. These results encourage further studies on TcCyP19 as an early biomarker of trypanocidal treatment efficiency.

Design and synthesis of new 1,2,3-triazoles derived from eugenol and analogues with in vitro and in vivo activity against Trypanosoma cruzi

Chagas disease (CD) is a neglected tropical disease endemic in 21 countries and affects about 8 million people around the world. The pharmacotherapy for this disease is limited to two drugs (Benznidazole and Nifurtimox) and both are associated with important limitations, as low cure rate in the chronic phase of the disease, high toxicity and increasing resistance by Trypanosoma cruzi. Recently, we reported a bioactive 1,2,3-triazole (compound 35) active in vitro (IC₅₀ 42.8 μM) and in vivo (100 mg/kg) against T. cruzi Y strains and preliminary in silico studies suggested the cysteine protease cruzain as a possible target. Considering these initial findings, we describe here the design and synthesis of new 1,2,3-triazoles derivatives of our hit compound (35). The triazoles were initially evaluated against healthy cells derived from neonatal rat cardiomyoblasts (H9c2 cells) to determine their cytotoxicity and against epimastigotes forms of T. cruzi Y strain. The most active triazoles were compounds 26 (IC₅₀ 19.7 μM) and 27 (IC₅₀ 7.3 μM), while benznidazole was active at 21.6 μM. Derivative 27 showed an interesting selectivity index considering healthy H9c2 cells (>77). Promising activities against trypomastigotes forms of the parasite were also observed for triazoles 26 (IC₅₀ 20.74 μM) and 27 (IC₅₀ 8.41 μM), mainly 27 which showed activity once again higher than that observed for benznidazole (IC₅₀ 12.72 μM). While docking results suggested cruzain as a potential target for these compounds, no significant enzyme inhibition was observed in vitro, indicating that their trypanocidal activity is related to another mode of action. Considering the promising in vitro results of triazoles 26 and 27, the in vivo toxicity was initially verified based on the evaluation of behavioral and physiological parameters, mortality, effect in body weight gain, and through the measurement of AST/ALT enzymes, which are markers of liver toxicity. All these evaluations pointed to a good tolerability of the animals, especially considering triazole 27. A reduction in parasitemia was observed among animals treated with triazole 27, but not among those treated with derivative 26. Regarding the dosage, derivative 27 (100 mg/kg) was the most active sample against T. cruzi infection, showing a 99.4% reduction in parasitemia peak. Triazole 27 at a dosage of 100 mg/kg influenced the humoral immune response and reduced myocarditis in the animals, bringing antibody levels closer to those observed among healthy mice. Altogether, our results indicate compound 27 as a new lead for the development of drug candidates to treat Chagas disease.

Population pharmacokinetics of benznidazole in neonates, infants and children using a new pediatric formulation

BACKGROUND

There is a major need for information on pharmacokinetics (PK) of benznidazole (BNZ) in children with Chagas disease (CD). We conducted a multicentre population PK, safety and efficacy study in children, infants and neonates with CD treated with BNZ (formulated in 100 mg tablets or 12.5 mg dispersible tablets, developed by the pharmaceutical company LAFEPE, in a collaboration with DNDi).

METHODS

81 children 0-12 years old were enrolled at 5 pediatric centers in Argentina. Diagnosis of T. cruzi infection was confirmed by direct microscopic examination, or at least two positive conventional serological tests. Subject enrolment was stratified by age: newborns to 2 years (minimum of 10 newborns) and >2-12 years. BNZ 7.5 mg/kg/d was administered in two daily doses for 60 days. Five blood samples per child were obtained at random times within pre-defined time windows at Day 0 at 2-5 h post-dose; during steady state, one sample at Day 7 and at Day 30; and two samples at 12-24 h after final BNZ dose at Day 60. The primary efficacy endpoint was parasitological clearance by qualitative PCR at the end of treatment.

RESULTS

Forty-one (51%) patients were under 2 years of age (including 14 newborns <1 month of age). Median age at enrolment was 22 months (mean: 43.2; interquartile range (IQR) 7-72 months). The median measured BNZ Cmax was 8.32 mg/L (IQR 5.95-11.8; range 1.79-19.38). Median observed BNZ Cmin (trough) concentration was 2 mg/L (IQR 1.25-3.77; range 0.14-7.08). Overall median simulated Css was 6.3 mg/L (IQR 4.7-8.5 mg/L). CL/F increased quickly during the first month of postnatal life and reached adult levels after approximately 10 years of age. Negative qPCR was observed at the end of treatment in all 76 patients who completed the treatment. Five patients discontinued treatment (3 due to AEs and 2 due to lack of compliance).

CONCLUSION

We observed lower BNZ plasma concentrations in infants and children than those previously reported in adults treated with comparable mg/kg doses. Despite these lower concentrations, pediatric treatment was well tolerated and universally effective, with a high response rate and infrequent, mild AEs.

TRIAL REGISTRATION

Registered in clinicaltrials.gov #NCT01549236.

ASP-2/Trans-sialidase chimeric protein induces robust protective immunity in experimental models of Chagas' disease

Immunization with the Amastigote Surface Protein-2 (ASP-2) and Trans-sialidase (TS) antigens either in the form of recombinant protein, encoded in plasmids or human adenovirus 5 (hAd5) confers robust protection against various lineages of Trypanosoma cruzi. Herein we generated a chimeric protein containing the most immunogenic regions for T and B cells from TS and ASP-2 (TRASP) and evaluated its immunogenicity in comparison with our standard protocol of heterologous prime-boost using plasmids and hAd5. Mice immunized with TRASP protein associated to Poly-ICLC (Hiltonol) were highly resistant to challenge with T. cruzi, showing a large decrease in tissue parasitism, parasitemia and no lethality. This protection lasted for at least 3 months after the last boost of immunization, being equivalent to the protection induced by DNA/hAd5 protocol. TRASP induced high levels of T. cruzi-specific antibodies and IFNγ-producing T cells and protection was primarily mediated by CD8⁺ T cells and IFN-γ. We also evaluated the toxicity, immunogenicity, and efficacy of TRASP and DNA/hAd5 formulations in dogs. Mild collateral effects were detected at the site of vaccine inoculation. While the chimeric protein associated with Poly-ICLC induced high levels of antibodies and CD4⁺ T cell responses, the DNA/hAd5 induced no antibodies, but a strong CD8⁺ T cell response. Immunization with either vaccine protected dogs against challenge with T. cruzi. Despite the similar efficacy, we conclude that moving ahead with TRASP together with Hiltonol is advantageous over the DNA/hAd5 vaccine due to pre-existing immunity to the adenovirus vector, as well as the cost-benefit for development and large-scale production.

B-Cell Responses in Chronic Chagas Disease: Waning of Trypanosoma cruzi-Specific Antibody-Secreting Cells Following Successful Etiological Treatment

BACKGROUND

A drawback in the treatment of chronic Chagas disease (American trypanosomiasis) is the long time required to achieve complete loss of serological reactivity, the standard for determining treatment efficacy.

METHODS

Antibody-secreting cells and memory B cells specific for Trypanosoma cruzi and their degree of differentiation were evaluated in adult and pediatric study participants with chronic Chagas disease before and after etiological treatment.

RESULTS

T. cruzi-specific antibody-secreting cells disappeared from the circulation in benznidazole or nifurtimox-treated participants with declining parasite-specific antibody levels after treatment, whereas B cells in most participants with unaltered antibody levels were low before treatment and did not change after treatment. The timing of the decay in parasite-specific antibody-secreting B cells was similar to that in parasite-specific antibodies, as measured by a Luminex-based assay, but preceded the decay in antibody levels detected by conventional serology. The phenotype of total B cells returned to a noninfection profile after successful treatment.

CONCLUSIONS

T. cruzi-specific antibodies in the circulation of chronically T. cruzi-infected study participants likely derive from both antigen-driven plasmablasts, which disappear after successful treatment, and long-lived plasma cells, which persist and account for the low frequency and long course to complete seronegative conversion in successfully treated participants.

Further Investigations of Nitroheterocyclic Compounds as Potential Antikinetoplastid Drug Candidates

Due to the lack of specific vaccines, management of the trypanosomatid-caused neglected tropical diseases (sleeping sickness, Chagas disease and leishmaniasis) relies exclusively on pharmacological treatments. Current drugs against them are scarce, old and exhibit disadvantages, such as adverse effects, parenteral administration, chemical instability and high costs which are often unaffordable for endemic low-income countries. Discoveries of new pharmacological entities for the treatment of these diseases are scarce, since most of the big pharmaceutical companies find this market unattractive. In order to fill the pipeline of compounds and replace existing ones, highly translatable drug screening platforms have been developed in the last two decades. Thousands of molecules have been tested, including nitroheterocyclic compounds, such as benznidazole and nifurtimox, which had already provided potent and effective effects against Chagas disease. More recently, fexinidazole has been added as a new drug against African trypanosomiasis. Despite the success of nitroheterocycles, they had been discarded from drug discovery campaigns due to their mutagenic potential, but now they represent a promising source of inspiration for oral drugs that can replace those currently on the market. The examples provided by the trypanocidal activity of fexinidazole and the promising efficacy of the derivative DNDi-0690 against leishmaniasis seem to open a new window of opportunity for these compounds that were discovered in the 1960s. In this review, we show the current uses of nitroheterocycles and the novel derived molecules that are being synthesized against these neglected diseases.

Microextraction by packed sorbent and high-performance liquid chromatography for determination of benznidazole in human plasma

Benznidazole is the main drug used in Chagas disease and its determination in plasma samples is useful in several situations. Hence, robust and accurate bioanalytical methods are needed. In this context, sample preparation deserves special attention, as it is the most error-prone, labor-intensive and time-consuming step. Microextraction by packed sorbent (MEPS) is a miniaturized technique, developed to minimize the use of hazardous solvents and sample amount. In this context, this study aimed to develop and validate a MEPS coupled to high performance liquid chromatography method for the analysis of benznidazole in human plasma. MEPS optimization was performed by a 2⁴ full factorial experimental design, which resulted in about 25 % of recovery. The best condition was achieved when 500 µL of plasma,10 draw-eject cycles, sample volume drawn of 100 µL, and desorption with three times of 50 µL of acetonitrile were used. The chromatographic separation was performed with a C18 (150 × 4.5 mm, 5 µm) column. The mobile phase was composed of water:acetonitrile (60:40) at a flow rate of 1.0 mL min^-1. The developed method was validated and proved to be selective, precise, accurate, robust and linear in the range from 0.5 to 6.0 µg mL^-1. The method was applied to three healthy volunteers that made use of benznidazole tablets and showed to be adequate to assess this drug in plasma samples.

Major benznidazole metabolites in patients treated for Chagas disease: Mass spectrometry-based identification, structural analysis and detoxification pathways

Benznidazole is the drug of choice for the treatment of Chagas disease, but its metabolism in humans is unclear. Here, we identified and characterized the major benznidazole metabolites and their biosynthetic mechanisms in humans by analyzing the ionic profiles of urine samples from patients and untreated donors through reversed-phase UHPLC-ESI-QTOF-MS and UHPLC-ESI-QqLIT-MS. A strategy for simultaneous detection and fragmentation of characteristic positive and negative ions was employed using information-dependent acquisitions (IDA). Selected precursor ions, neutral losses, and MS³ experiments complemented the study. A total of six phase-I and ten phase-II metabolites were identified and structurally characterized in urine of benznidazole-treated patients. Based on creatinine-corrected ion intensities, nitroreduction to amino-benznidazole (M1) and its subsequent N-glucuronidation to M5 were the main metabolic pathways, followed by imidazole-ring cleavage, oxidations, and cysteine conjugations. This extensive exploration of benznidazole metabolites revealed potentially toxic structures in the form of glucuronides and glutathione derivatives, which may be associated with recurrent treatment adverse events; this possibility warrants further exploration in future clinical trials. Incorporation of this knowledge of the benznidazole metabolic profile into clinical pharmacology trials could lead to improved treatments, facilitate the study of possible drug-drug interactions, and even mitigation of adverse drug reactions.

Direct evidence gap on fixed versus adjusted-dose benznidazole for adults with chronic Chagas disease without cardiomyopathy: Systematic review and individual patient data meta-analysis

OBJECTIVES

To determine the comparative efficacy and safety of a fixed dose of benznidazole (BZN) with an adjusted-dose for Trypanosoma cruzi-seropositive adults without cardiomyopathy.

METHODS

We conducted a systematic review and individual participant data (IPD) meta-analysis following Cochrane methods, and the PRISMA-IPD statement for reporting. Randomised controlled trials (RCTs) allocating participants to fixed or adjusted doses of BZN for T. cruzi-seropositive adults without cardiomyopathy were included. We searched (December 2021) Cochrane, MEDLINE, EMBASE, LILACS and trial registries and contacted Chagas experts. Selection, data extraction, risk of bias assessment using the Cochrane tool, and a GRADE summary of finding tables were performed independently by pairs of reviewers. We conducted a random-effects IPD meta-analysis using the one-stage strategy, or, if that was impossible, the two-stage strategy.

RESULTS

Five RCTs (1198 patients) were included, none directly comparing fixed with adjusted doses of BZN. Compared to placebo, BZN therapy was strongly associated with negative qPCR and sustainable parasitological clearance regardless of the type of dose and subgroup analysed. For negative qPCR, the fixed/adjusted rate of odds ratios (ROR^F/A ) was 8.83 (95% CI 1.02-76.48); for sustained parasitological clearance, it was 4.60 (95% CI 0.40-52.51), probably indicating at least non-inferior effect of fixed doses, with no statistically significant interactions by scheme for global and most subgroup estimations. The ROR^F/A for treatment interruption due to adverse events was 0.44 (95% CI 0.14-1.38), probably indicating no worse tolerance of fixed doses.

CONCLUSIONS

We found no direct comparison between fixed and adjusted doses of BZN. However, fixed doses versus placebo are probably not inferior to weight-adjusted doses of BZN versus placebo in terms of parasitological efficacy and safety. Network IPD meta-analysis, through indirect comparisons, may well provide the best possible answers in the near future.

REGISTRATION

The study protocol was registered in PROSPERO (CRD42019120905).

Solid Nanomedicines of Nifurtimox and Benznidazole for the Oral Treatment of Chagas Disease

Chagas disease (CD) is a parasitic zoonosis endemic in Central and South America affecting nearly 10 million people, with 100 million people at high risk of contracting the disease. Treatment is only effective when received at the early stages of the disease and it involved two drugs (nifurtimox (NFX) and benznidazole (BNZ)). Both treatments require multiple daily administrations of high doses, suffer from variable efficacy and insufficient efficacy in chronic CD, many side effects, and a very long duration of treatment that results in poor compliance, while combined available therapies that lead to reduced duration of treatment are not available and polypharmacy reduces compliance and increases the cost further. Here we present self-nanoemulsified drug delivery systems (SNEDDS) able to produce easily scalable combined formulations of NFX and BNZ that can allow for tailoring of the dose and can be easily converted to oral solid dosage form by impregnation on mesoporous silica particles. SNEDDS demonstrated an enhanced solubilisation capacity for both drugs as demonstrated by flow-through studies and in vitro lipolysis studies. High loading of SNEDDS to Syloid 244 and 3050 silicas (2:1 w/w) allowed clinically translatable amounts of both NFX and BNZ to be loaded. Tablets prepared from NFX-BNZ combined SNEDDS loaded on Syloid 3050 silicas demonstration near complete dissolution in the flow through cell apparatus compared to NFX and BNZ commercial tablets respectively (Lampit^® and Rochagan^®). NFX-BNZ-SNEDDS demonstrated nanomolar efficacy in epimastigotes and amastigotes of T. cruzi with acceptable selectivity indexes and demonstrated enhanced survival and reduced parasitaemia in acute murine experimental models of CD. Thus, the results presented here illustrate the ability for an easily scalable and personalised combination oral therapy prepared from GRAS excipients, enabling treatment access worldwide for the treatment of CD.

A Phase 2, Randomized, Multicenter, Placebo-Controlled, Proof-of-Concept Trial of Oral Fexinidazole in Adults With Chronic Indeterminate Chagas Disease

BACKGROUND

Chagas disease (CD) has significant global health impact, but safe, effective treatments remain elusive. The nitroimidazole fexinidazole is a potential treatment.

METHODS

This double-blind, randomized, placebo-controlled, dose-finding, proof-of-concept study was conducted in Bolivia. Adults with serologically confirmed chronic indeterminate CD and positive PCR were randomly assigned to 1 of 6 fexinidazole regimens (1200 or 1800 mg/day for 2, 4, or 8 weeks) or placebo. Target recruitment was 20 patients/arm. The primary endpoint was sustained parasitological clearance by serial negative qPCR from end of treatment (EOT) until 6 months follow-up in the intention-to-treat (ITT) population. Follow-up was extended to 12 months.

RESULTS

Enrollment was interrupted after 4/47 patients presented with transient asymptomatic grade 3 and 4 neutropenia. Treatment of ongoing patients was stopped in all patients administered >2 weeks. A total of 40 patients received treatment with fexinidazole from 3 days to 8 weeks. Delayed-onset neutropenia (n = 8) and increased liver enzymes (n = 8) were found in fexinidazole patients vs none in the placebo arm. In the ITT analysis, sustained parasitological clearance from EOT to 12 months follow-up varied between 66.7% (1200 mg-2 week) and 100.0% (1800 mg-2 week). Rapid, sustained clearance of parasitemia was observed in all treated patients with available data, but not in any patients in the placebo group, at 12 months (P = .0056). Further exploratory exposure-response analysis suggested low dosages of fexinidazole may be safe and effective.

CONCLUSIONS

Further evaluation is needed to establish fexinidazole's minimum effective dosage and risk-benefit relationship. Results suggest potential for effective treatment regimens <10 days.

CLINICAL TRIALS REGISTRATION

NCT02498782.

Pediatric Chagas disease in the non-endemic area of Madrid: A fifteen-year review (2004–2018)

Background

Chagas disease (CD) has become an emerging global health problem in association with the immigration of individuals from endemic areas (in LatinAmerica) to other countries.Spain is the country in Europe with the highest number of CD cases. Concerning pediatric CD, treatment is not only better tolerated by younger children but also has greater cure possibilities. The aim of this study was to describe clinical and epidemiological aspects of CD in a pediatric population diagnosed of 10 hospitals in the Community of Madrid during the 2004–2018 period, as well as the safety and efficacy of CD treatment on this population.

Methodology/Principal findings

A multicenter, retrospective, descriptive study was conducted. The studied population included all identified children under the age of 18 with a diagnosis of CD. Diagnosis was performed with a positive parasitological test (with subsequent confirmation) or confirmed persistence of positive serology beyond 9 months, for children younger than one year-old, and with two different positive serological tests, for children older than one.

Fifty-one children were included (59% male; 50.9% born in Spain). All mothers were from Latin America. The median age at diagnosis was 0.7 months for those under one year of age, and 11.08 years for those older than one year-old. Only one case presented a symptomatic course (hydrops faetalis, haemodynamic instability at birth, ascites, anaemia). For 94% treatment was completed. Considering patients who received benznidazole (47), AE were recorded in 48,9%. Among the 32 patients older than one year-old treated with benznidazole, 18 (56.25%) had adverse events whereas in the 15 under one year, 5(33,3%) did. Eigtheen (78.2%) of the patients with benznidazole AE were older than one year-old(median age 11.4 years). Of the patients treated with nifurtimox (9), AE were reported in 3 cases (33,3%).

Cure was confirmed in 80% of the children under one year-old vs 4.3% in those older (p<0.001). Loss to follow- up occurred in 35.3% of patients.

Conclusions/Significances

Screening programs of CD since birth allow early diagnosis and treatment, with a significantly higher cure rate in children treated before one year of age, with lower incidence of adverse events. The high proportion of patients lost to follow-up in this vulnerable population is of concern.

Chagas disease, caused by the protozoan Trypanosoma cruzi, has traditionally been confined to endemic locations in South America (with vectorial transmission), but is nowadays emerging in Europe, mainly in Spain, due to immigration.

A series of characteristics of this disease condition its management. It is usually asymptomatic (especially in early stages), it can be transmitted from mothers to child (vertical transmission) and treatment is more effective at a younger age or during the early stages of infection. For these reasons early diagnosis and treatment of infected children is a priority. To date, there are few publications on pediatric CD series in non-endemic regions. In this paper we describe the epidemiological and clinical characteristics of 51 children diagnosed with pediatric CD in a non-endemic area, as well as the the safety and efficacy of treatment in this patient population.

We found that most patients were asymptomatic at diagnosis. The cure percentage was clearly higher when they were treated before one year-old (80% vs 4.3% in children older than one).Adverse events to treatment have occurred especially in older children, being frequent in this age group (median age 11 years).

The high proportion of patients lost to follow-up that occurs in this vulnerable population is also noteworthy (35.3% in our case). We highlight, as a conclusion of our study, the need of carrying out systematic screening for this disease (women of childbearing age, children of mothers with positive serology) to reduce the rate of vertical transmission and to achieve higher cure rates and better tolerance to treatment.

Review of pharmacological options for the treatment of Chagas disease

Chagas disease (CD) is a worldwide problem, with over 8 million people infected in both rural and urban areas. CD was first described over a century ago, but only two drugs are currently available for CD treatment: benznidazole (BZN) and nifurtimox (NF). Treating CD-infected patients, especially children and women of reproductive age, is vital in order to prevent long-term sequelae, such as heart and gastrointestinal dysfunction, but this aim is still far from being accomplished. Currently, the strongest data to support benefit-risk considerations come from trials in children. Treatment response biomarkers need further development as serology is being questioned as the best method to assess treatment response. This article is a narrative review on the pharmacology of drugs for CD, particularly BZN and NF. Data on drug biopharmaceutical characteristics, safety and efficacy of both drugs are summarized from a clinical perspective. Current data on alternative compounds under evaluation for CD treatment, and new possible treatment response biomarkers are also discussed. Early diagnosis and treatment of CD, especially in paediatric patients, is vital for an effective and safe use of the available drugs (i.e. BZN and NF). New biomarkers for CD are urgently needed for the diagnosis and evaluation of treatment efficacy, and to guide efforts from academia and pharmaceutical companies to accelerate the process of new drug development.

Association of HLA-B*35 and moderate or severe cutaneous reactions secondary to benznidazole treatment in chronic Chagas disease patients

OBJECTIVES

Benznidazole is the first line treatment for Chagas disease. Adverse events appear in more than 50% of patients, leading to discontinuation in approximately 15%. Cutaneous reactions are one of the most frequent adverse events. HLA-genotyping previous studies identified an association between cutaneous reactions to benznidazole and carrying the specific allele HLA-B*35:05. We designed the present study to prospectively confirm this association.

METHODS

This is a prospective observational study including Chagas disease patients aged 18 years or more who accepted to receive benznidazole treatment following current guidelines. Allele genotyping of HLA-B was determined in all patients. Clinical and analytical follow-up was performed at days 0, 7, 14, 30 and 60 of treatment.

RESULTS

Two-hundred and seven patients were included. Seventy percent were female with a mean age of 45.1 (SD ±9.86) years mainly from Bolivia (92.8%). In 102 (49.3%) cases a cutaneous reaction was diagnosed. Forty-eight (46.6%) were classified as mild, 37 (35.9%) as moderate and 18 (17.5%) as severe. Thirty-two (15.4%) patients had to definitively interrupt the treatment due to a cutaneous reaction. Female sex (OR 4.49; 95%CI 1.62-12.47), new-onset eosinophilia prior to cutaneous symptoms (OR 2.55; 95%CI 1.2-5.43) and carrying the HLA-B*35 allelic group (OR 2.58; 95%CI 1.2-5.51) were all predictors of moderate to severe cutaneous reactions. No statistical significance was found when the specific allele HLA-B*35:05 was analyzed.

CONCLUSIONS

Patients carrying the HLA-B*35 allelic group are at higher risk of moderate to severe reactions when taking benznidazole treatment.

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.

Oxidative stress implications for therapeutic vaccine development against Chagas disease

INTRODUCTION

Pathogenesis of Chagas disease (CD) caused by the protozoan parasite Trypanosoma cruzi (T. cruzi) involves chronic oxidative and inflammatory stress. In this review, we discuss the research efforts in therapeutic vaccine development to date and the potential challenges imposed by oxidative stress in achieving an efficient therapeutic vaccine against CD.

AREAS COVERED

This review covers the immune and nonimmune mechanisms of reactive oxygen species production and immune response patterns during T. cruzi infection in CD. A discussion on immunotherapy development efforts, the efficacy of antigen-based immune therapies against T. cruzi, and the role of antioxidants as adjuvants is discussed to provide promising insights to developing future treatment strategies against CD.

EXPERT OPINION

Administration of therapeutic vaccines can be a good option to confront persistent parasitemia in CD by achieving a rapid, short-lived stimulation of type 1 cell-mediated immunity. At the same time, adjunct therapies could play a critical role in the preservation of mitochondrial metabolism and cardiac muscle contractility in CD. We propose combined therapy with antigen-based vaccine and small molecules to control the pathological oxidative insult would be effective in the conservation of cardiac structure and function in CD.

Tolerance to nifurtimox and benznidazole in adult patients with chronic Chagas' disease

BACKGROUND

Current options for Chagas' disease treatment are restricted to benznidazole and nifurtimox. To the best of our knowledge, no study has ever compared their tolerance in adults in a non-endemic country.

OBJECTIVES

To compare the completion rates and drug tolerance in a cohort of patients treated according to current guidelines.

PATIENTS AND METHODS

We analysed the medical records of all Chagas' disease patients aged 18 years or over who started antiparasitic treatment at the Geneva University Hospitals, Switzerland, from 2008 to 2016. We recorded treatment duration and all adverse events.

RESULTS

We included 176 patients, 92 and 84 of whom received benznidazole or nifurtimox, respectively. The overall treatment completion rate was 62.5%, without a significant difference between the groups (P=0.436). Most patients (89.8%) suffered at least one adverse event. Those receiving nifurtimox had more events (6.2 versus 3.5, P<0.001). Mucocutaneous symptoms predominated in the benznidazole group, whereas digestive symptoms were most frequent with nifurtimox. Neuropsychiatric events frequently occurred in both groups, most notably in patients receiving nifurtimox. Arthralgia, dyspnoea, sensitive neuropathy and pruritus were independent predictors of treatment interruption.

CONCLUSIONS

Currently recommended drug regimens for Chagas' disease are not well tolerated and entail frequent treatment discontinuation irrespective of the drug used. This highlights the need to improve treatment tolerance in adults with Chagas' disease with new therapeutic options.

Structure Activity Relationship of N-Substituted Phenyldihydropyrazolones Against Trypanosoma cruzi Amastigotes

Current drugs for Chagas disease have long treatment regimens with occurrence of adverse drug effects leading to poor treatment compliance. Novel and efficacious medications are therefore highly needed. We previously reported on the discovery of NPD-0227 (2-isopropyl-5-(4-methoxy-3-(pyridin-3-yl)phenyl)-4,4-dimethyl-2,4-dihydro-3H-pyrazol-3-one) as a potent in vitro inhibitor of Trypanosoma cruzi (pIC50 = 6.4) with 100-fold selectivity over human MRC-5 cells. The present work describes a SAR study on the exploration of substituents on the phenylpyrazolone nitrogen. Modifications were either done directly onto this pyrazolone nitrogen or alternatively by introducing a piperidine linker. Attention was pointed toward the selection of substituents with a cLogP preferably below NPD-0227s cLogP of 3.5. Generally the more apolar compounds showed better activities then molecules with cLogPs <2.0. Several new compounds were identified with potencies that are in the same range as NPD-0227 (pIC50 = 6.4) and promising selectivities. While the potency could not be improved, valuable SAR was obtained. Furthermore the introduction of a piperidine linker offers new opportunities for derivatization as valuable novel starting points for future T. cruzi drug discovery.

Virtual Screening Based on QSAR and Molecular Docking of Possible Inhibitors Targeting Chagas CYP51

Chagas is a neglected tropical disease caused by the parasite Trypanosoma cruzi with no effective treatment in all its forms. There is a need to find more effective therapeutic alternatives with reduced toxicity. In this contribution, multiple linear regression models were used to identify the molecular descriptors that best describe the inhibitory activity of 52 fenarimol analogues against Trypanosoma cruzi. The topological, physicochemical, thermodynamic, electronic, and charge descriptors were evaluated to cover a wide range of properties that frequently encode biological activity. A model with high predictive value was obtained based on geometrical descriptors and descriptors encoding hydrophobicity and London dispersion forces as necessary for the inhibition of Trypanosoma cruzi-CYP51. Docking methodology was implemented to evaluate molecular interactions in silico. The virtual screening results in this study can be used for rational design of new analogues with improved activity against Chagas disease.

Pharmacogenomic Profile and Adverse Drug Reactions in a Prospective Therapeutic Cohort of Chagas Disease Patients Treated with Benznidazole

Chagas disease remains a major social and public health problem in Latin America. Benznidazole (BZN) is the main drug with activity against Trypanosoma cruzi. Due to the high number of adverse drug reactions (ADRs), BZN is underprescribed. The goal of this study was to evaluate the genetic and transcriptional basis of BZN adverse reactions. Methods: A prospective cohort with 102 Chagas disease patients who underwent BZN treatment was established to identify ADRs and understand their genetic basis. The patients were classified into two groups: those with at least one ADR (n = 73), and those without ADRs (n = 29). Genomic analyses were performed comparing single nucleotide polymorphisms between groups. Transcriptome data were obtained comparing groups before and after treatment, and signaling pathways related to the main ADRs were evaluated. Results: A total of 73 subjects (71.5%) experienced ADRs. Dermatological symptoms were most frequent (45.1%). One region of chromosome 16, at the gene LOC102724084 (rs1518601, rs11861761, and rs34091595), was associated with ADRs (p = 5.652 × 10⁻⁸). Transcriptomic data revealed three significantly enriched signaling pathways related to BZN ADRs. Conclusions: These data suggest that part of adverse BZN reactions might be genetically determined and may facilitate patient risk stratification prior to starting BZN treatment.

The design, synthesis, and in vitro trypanocidal and leishmanicidal activities of 1,3-thiazole and 4-thiazolidinone ester derivatives

Chagas and leishmaniasis are both neglected tropical diseases, whose inefficient therapies have made them remain the cause for millions of deaths worldwide. Given this, we synthesized 27 novel 1,3-thiazoles and 4-thiazolidinones using bioisosteric and esterification strategies to develop improved and safer drug candidates. After an easy, rapid and low-cost synthesis with satisfactory yields, compounds were structurally characterized. Then, in vitro assays were performed, against Leishmania infantum and Leishmania amazonensis promastigotes, Trypanosoma cruzi trypomastigotes and amastigotes, for selected compounds to determine IC₅₀ and SI, with cytotoxicity on LLC-MK2 cell lines. Overall, 1,3-thiazoles exhibited better trypanocidal activity than 4-thiazolidinones. The compound 1f, an ortho-bromobenzylidene-substituted 1,3-thiazole (IC₅₀ = 0.83 μM), is the most potent of them all. In addition, compounds had negligible cytotoxicity in mammalian cells (CC₅₀ values > 50 μM). Also noteworthy is the examination of the cell death mechanism of T. cruzi, which showed that compound 1f induced necrosis and apoptosis in the parasite. Scanning electron microscopy analysis demonstrated that the treatment of Trypanosoma cruzi trypomastigote cells with the compound 1f at different IC₅₀ concentrations promoted alterations in the shape, flagella and body surface, inducing parasite death. Together, our data revealed a novel series of 1,3-thiazole structure-based compounds with promising activity against Trypanosoma cruzi and Leishmania spp., broadening ways for scaffold optimization.

Chagas and leishmaniasis are both neglected tropical diseases, whose inefficient therapies have made them remain the cause for millions of deaths worldwide.

Development and Evaluation of a Three-Dimensional Printer-Based DNA Extraction Method Coupled to Loop Mediated Isothermal Amplification for Point-of-Care Diagnosis of Congenital Chagas Disease in Endemic Regions

Vertical transmission of Trypanosomacruzi is the cause of congenital Chagas disease, a re-emerging infectious disease that affects endemic and nonendemic regions alike. An early diagnosis is crucial because prompt treatment achieves a high cure rate, precluding evolution to symptomatic chronic Chagas disease. However, early diagnosis involves low-sensitive parasitologic assays, making necessary serologic confirmation after 9 months of life. With the aim of implementing early diagnostic strategies suitable for minimally equipped laboratories, a T. cruzi-loop-mediated isothermal amplification (LAMP) prototype was coupled with an automated DNA-extraction device repurposed from a three-dimensional printer (PrintrLab). The whole process takes <3 hours to yield a result, with an analytical sensitivity of 0.1 to 2 parasite equivalents per milliliter, depending on the T. cruzi strain. Twenty-five blood samples from neonates born to seropositive mothers were tested blindly. In comparison to quantitative real-time PCR, the PrintrLab-LAMP dual strategy showed high agreement, while both molecular-based methodologies yielded optimal sensitivity and specificity with respect to microscopy-based diagnosis of congenital Chagas disease. PrintrLab-LAMP detected all 10 congenitally transmitted T. cruzi infections, showing promise for point-of-care early diagnosis of congenital Chagas disease.

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.

Strengthening the Bolivian pharmacovigilance system: New surveillance strategies to improve care for Chagas disease and tuberculosis

Chagas disease (CD) and tuberculosis (TB) are important health problems in Bolivia. Current treatments for both infections require a long period of time, and adverse drug reactions (ADRs) are frequent. This study aims to strengthen the Bolivian pharmacovigilance system, focusing on CD and TB. A situation analysis of pharmacovigilance in the Department of Cochabamba was performed. The use of a new local case report form (CRF) was implemented, together with the CRF established by the Unidad de Medicamentos y Tecnología en Salud (UNIMED), in several healthcare centers. Training and follow-up on drug safety monitoring and ADR reporting was provided to all health professionals involved in CD and TB treatment. A comparative analysis of the reported ADRs using the CRF provided by UNIMED, the new CRF proposal, and medical records, was also performed. Our results showed that out of all patients starting treatment for CD, 37.9% suffered ADRs according to the medical records, and 25.3% of them were classified as moderate/severe (MS). Only 47.4% of MS ADRs were reported to UNIMED. Regarding TB treatment, 9.9% of all patients suffered ADRs, 44% of them were classified as MS, and 75% of MS ADRs were reported to UNIMED. These findings show that the reinforcement of the Bolivian pharmacovigilance system is an ambitious project that should involve a long-term perspective and the engagement of national health workers and other stakeholders at all levels. Continuity and perseverance are essential to achieve a solid ADR reporting system, improving patient safety, drug efficacy and adherence to treatment.

Short-course Benznidazole treatment to reduce Trypanosoma cruzi parasitic load in women of reproductive age (BETTY): a non-inferiority randomized controlled trial study protocol

BACKGROUND

Retrospective observational studies suggest that transmission of Trypanosoma cruzi does not occur in treated women when pregnant later in life. The level of parasitemia is a known risk factor for congenital transmission. Benznidazole (BZN) is the drug of choice for preconceptional treatment to reduce parasitic load. The fear of treatment-related side effects limits the implementation of the Argentine guideline recommending BZN 60d/300 mg (or equivalent) treatment of T. cruzi seropositive women during the postpartum period to prevent transmission in a future pregnancy. A short and low dose BZN treatment might reduce major side effects and increase compliance, but its efficacy to reduce T. cruzi parasitic load compared to the standard 60d/300 mg course is not yet established. Clinical trials testing alternative BZN courses among women of reproductive age are urgently needed.

METHODS AND DESIGN

We are proposing to perform a double-blinded, non-inferiority randomized controlled trial comparing a short low dose 30-day treatment with BZN 150 mg/day (30d/150 mg) vs. BZN 60d/300 mg. We will recruit not previously treated T. cruzi seropositive women with a live birth during the postpartum period in Argentina, randomize them at 6 months postpartum, and follow them up with the following specific aims: Specific aim 1: to measure the effect of BZN 30d/150 mg compared to 60d/300 mg preconceptional treatment on parasitic load measured by the frequency of positive Polymerase Chain Reaction (PCR) (primary outcome) and by real-time quantitative PCR (qPCR), immediately and 10 months after treatment. Specific aim 2: to measure the frequency of serious adverse events and/or any adverse event leading to treatment interruption.

TRIAL REGISTRATION

ClinicalTrials.gov . Identifier: NCT03672487 . Registered 14 September 2018.

Fixed vs adjusted-dose benznidazole for adults with chronic Chagas disease without cardiomyopathy: A systematic review and meta-analysis

Chagas disease is a neglected disease that remains a public health threat, particularly in Latin America. The most important treatment options are nitroimidazole derivatives, such as nifurtimox and benznidazole (BZN). Some studies suggest that for adults seropositive to T. cruzi but without clinically evident chronic Chagas cardiomyopathy (CCC), a simple fixed-dose scheme of BZN could be equivalent to a weight-adjusted dose. We compared the efficacy and safety of a fixed dose of BZN with an adjusted dose for T. cruzi seropositive adults without CCC. We used the Cochrane methods, and reported according to the PRISMA statement. We included randomized controlled trials (RCTs) allocating participants to fixed and/or adjusted doses of BZN for T. cruzi seropositive adults without CCC. We searched (December 2019) Cochrane, MEDLINE, EMBASE, LILACS, Clinicaltrials.gov, and International Clinical Trials Registry Platform (ICTRP), and contacted Chagas experts. Selection, data extraction, and risk of bias assessment, using the Cochrane tool, were performed independently by pairs of reviewers. Discrepancies were solved by consensus within the team. Primary outcomes were parasite-related outcomes and efficacy or patient-related safety outcomes. We conducted a meta-analysis using RevMan 5.3 software and used GRADE summary of finding tables to present the certainty of evidence by outcome. We identified 655 records through our search strategy and 10 studies (four of them ongoing) met our inclusion criteria. We did not find any study directly comparing fixed vs adjusted doses of BZN, however, some outcomes allowed subgroup comparisons between fixed and adjusted doses of BZN against placebo. Moderate-certainty evidence suggests no important subgroup differences for positive PCR at one year and for three safety outcomes (drug discontinuation, peripheral neuropathy, and mild rash). The same effect was observed for any serious adverse events (low-certainty evidence). All subgroups showed similar effects (I2 0% for all these subgroup comparisons but 32% for peripheral neuropathy), supporting the equivalence of BZN schemes. We conclude that there is no direct evidence comparing fixed and adjusted doses of BZN. Based on low to very low certainty of evidence for critical clinical outcomes and moderate certainty of evidence for important outcomes, fixed and adjusted doses may be equivalent in terms of safety and efficacy. An individual patient data network meta-analysis could better address this issue.

Ideal benznidazole dose regimen in chronic chagasic patients: a systematic review

The present study aimed to review the existing literature and to evaluate the best dose regimen for benznidazole in adult patients with Chagas disease in the chronic phase. A systematic review was conducted followed by meta-analysis. Searches were performed in four databases, to include studies published until May 2019. The descriptors used were: "Chagas disease", "benznidazole", "Drug Therapy", "Pharmacokinetics", "Dose-response relationship, drug" and "Chronic disease". The meta-analysis compared studies using the standard dose of 5 mg/kg/day for 30 or 60 days. A total of 608 articles were found, 23 of which were considered eligible for this review and nine were included in the meta-analysis. The studies selected and analyzed were published between 1996 and 2018, with various benznidazole dose regimens, ranging from 2.5 mg/kg/day to 10 mg/kg/day, for 30 to 80 days of treatment. The results pointed to a great diversity of dose regimens, thus there is no consensus on the optimal dose regimen for benznidazole in the chronic phase of Chagas disease.

Structure-Activity Relationship of Phenylpyrazolones against Trypanosoma cruzi

Chagas disease is a neglected parasitic disease caused by the parasitic protozoan Trypanosoma cruzi and currently affects around 8 million people. Previously, 2-isopropyl-5-(4-methoxy-3-(pyridin-3-yl)phenyl)-4,4-dimethyl-2,4-dihydro-3H-pyrazol-3-one (NPD-0227) was discovered to be a sub-micromolar inhibitor (pIC50 =6.4) of T. cruzi. So far, SAR investigations of this scaffold have focused on the alkoxy substituent, the pyrazolone nitrogen substituent and the aromatic substituent of the core phenylpyrazolone. In this study, modifications of the phenyldihydropyrazolone scaffold are described. Variations were introduced by installing different substituents on the phenyl core, modifying the geminal dimethyl and installing various bio-isosteres of the dihydropyrazolone group. The anti T. cruzi activity of NPD-0227 could not be surpassed as the most potent compounds show pIC50 values of around 6.3. However, valuable additional SAR data for this interesting scaffold was obtained, and the data suggest that a scaffold hop is feasible as the pyrazolone moiety can be replaced by a oxazole or oxadiazole with minimal loss of activity.

Emerging agents for the treatment of Chagas disease: what is in the preclinical and clinical development pipeline?

INTRODUCTION

Chagas disease treatment relies on the lengthy administration of benznidazole and/or nifurtimox, which have frequent toxicity associated. The disease, caused by the parasite Trypanosoma cruzi, is mostly diagnosed at its chronic phase when life-threatening symptomatology manifest in approximately 30% of those infected. Considering that both available drugs have variable efficacy by then, and there are over 6 million people infected, there is a pressing need to find safer, more efficacious drugs.

AREAS COVERED

We provide an updated view of the path to achieve the aforementioned goal. From state-of-the-art in vitro and in vivo assays based on genetically engineered parasites that have allowed high throughput screenings of large chemical collections, to the unfulfilled requirement of having treatment-response biomarkers for the clinical evaluation of drugs. In between, we describe the most promising pre-clinical hits and the landscape of clinical trials with new drugs or new regimens of existing ones. Moreover, the use of monkey models to reduce the pre-clinical to clinical attrition rate is discussed.

EXPERT OPINION

In addition to the necessary research on new drugs and much awaited biomarkers of treatment efficacy, a key step will be to generalize access to diagnosis and treatment and maximize efforts to impede transmission.

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.

Implications of asymptomatic infection for the natural history of selected parasitic tropical diseases

Progress has been made in the control or elimination of tropical diseases, with a significant reduction of incidence. However, there is a risk of re-emergence if the factors fueling transmission are not dealt with. Although it is essential to understand these underlying factors for each disease, asymptomatic carriers are a common element that may promote resurgence; their impact in terms of proportion in the population and role in transmission needs to be determined. In this paper, we review the current evidence on whether or not to treat asymptomatic carriers given the relevance of their role in the transmission of a specific disease, the efficacy and toxicity of existing drugs, the Public Health interest, and the benefit at an individual level, for example, in Chagas disease, to prevent irreversible organ damage. In the absence of other control tools such as vaccines, there is a need for safer drugs with good risk/benefit profiles in order to change the paradigm so that it addresses the complete infectious process beyond manifest disease to include treatment of non-symptomatic infected persons.

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 4-((1-(1H-imidazol-2-yl)alkoxy)methyl)pyridines as a new class of Trypanosoma cruzi growth inhibitors

The identification of a new series of growth inhibitors of Trypanosoma cruzi, the causative agent of Chagas' disease, is described. In vitro screening of a subset of compounds from our in-house compound collection against the parasite led to the identification of hit compound 1 with low micromolar inhibition of T. cruzi growth. SAR exploration on the hit compound led to the identification of compounds that show nanomolar parasite growth inhibition (T. cruzi EC₅₀ ≤ 100 nM) and no cytotoxicity in human cells (HeLa CC₅₀ > 50 μM). Further investigation identified CYP51 inhibition (compound 11 CYP51 IC₅₀ 52 nM) as a possible mechanism of action of this new class of anti-parasitic agents.

Screening Marine Natural Products for New Drug Leads against Trypanosomatids and Malaria

Neglected Tropical Diseases (NTD) represent a serious threat to humans, especially for those living in poor or developing countries. Almost one-sixth of the world population is at risk of suffering from these diseases and many thousands die because of NTDs, to which we should add the sanitary, labor and social issues that hinder the economic development of these countries. Protozoan-borne diseases are responsible for more than one million deaths every year. Visceral leishmaniasis, Chagas disease or sleeping sickness are among the most lethal NTDs. Despite not being considered an NTD by the World Health Organization (WHO), malaria must be added to this sinister group. Malaria, caused by the apicomplexan parasite Plasmodium falciparum, is responsible for thousands of deaths each year. The treatment of this disease has been losing effectiveness year after year. Many of the medicines currently in use are obsolete due to their gradual loss of efficacy, their intrinsic toxicity and the emergence of drug resistance or a lack of adherence to treatment. Therefore, there is an urgent and global need for new drugs. Despite this, the scant interest shown by most of the stakeholders involved in the pharmaceutical industry makes our present therapeutic arsenal scarce, and until recently, the search for new drugs has not been seriously addressed. The sources of new drugs for these and other pathologies include natural products, synthetic molecules or repurposing drugs. The most frequent sources of natural products are microorganisms, e.g., bacteria, fungi, yeasts, algae and plants, which are able to synthesize many drugs that are currently in use (e.g. antimicrobials, antitumor, immunosuppressants, etc.). The marine environment is another well-established source of bioactive natural products, with recent applications against parasites, bacteria and other pathogens which affect humans and animals. Drug discovery techniques have rapidly advanced since the beginning of the millennium. The combination of novel techniques that include the genetic modification of pathogens, bioimaging and robotics has given rise to the standardization of High-Performance Screening platforms in the discovery of drugs. These advancements have accelerated the discovery of new chemical entities with antiparasitic effects. This review presents critical updates regarding the use of High-Throughput Screening (HTS) in the discovery of drugs for NTDs transmitted by protozoa, including malaria, and its application in the discovery of new drugs of marine origin.

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.

Characterization of adverse reactions to benznidazole in patients with Chagas disease in the Federal District, Brazil

INTRODUCTION

Benznidazole is used for treating Chagas disease (CD). This cross-sectional study aimed to characterize the adverse drug reactions (ADRs) of benznidazole at a public hospital in Brazil's Federal District.

METHODS

Medical records were analyzed and ADRs were categorized by type, intensity, seriousness, and causality.

RESULTS

Of the 62 patients who started benznidazole treatment for CD, 41 (66%) presented with 105 ADRs; 23 (37%) discontinued the treatment. Most reactions were classified as probable (81%), severe (63%), serious (67%), and dose-dependent (56%).

CONCLUSIONS

The high incidence of ADRs because of treatment withdrawal revealed the need for safer alternatives for CD treatment.

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.

The effect of benznidazole dose among the efficacy outcome in the murine animal model. A quantitative integration of the literature

Despite more than 100 years since it was firstly described Chagas disease, only two drugs are available to treat Chagas disease: Nifurtimox launched by Bayer in 1965 and benznidazole launched by Roche in 1971. Drug discovery initiatives have been looking for new compounds as an alternative to these old drugs. Although new platforms have been used with the latest technologies, a critical step on that process still relies on the in vivo model. Unfortunately, to date, available animal models have limited predictive value and there is no standardization. With the aim to better understand the role of benznidazole, the current standard of care of Chagas disease, we performed this review. We intend to analyze the influence of the experimental design of the most used animal model, the murine model, in the assessment of the efficacy endpoint.

Comparison of the toxicity of two treatment schemes with benznidazole for chronic Chagas disease: a prospective cohort study in two Spanish referral centres

OBJECTIVES

Chagas disease (CD) treatment is limited to two therapeutic options: benznidazole (generally the first option in Spain) and nifurtimox. Both drugs present high rates of adverse reactions and treatment discontinuation and there is no consensus regarding the most effective administration schedule for benznidazole or how to prevent and manage treatment toxicity. We aim to compare the tolerability and treatment discontinuation rate between two different treatment schemes with benznidazole.

METHODS

This was a prospective observational study of adult patients with CD, enrolled from January 2014 to March 2018 in two referral centres in Madrid (Spain). Participants were treated either with benznidazole 5 mg/kg/day (full dose) over 60 days (benznidazole standard dose scheme (BSD)), or with an escalating dose lasting 5 days up to a maximum of 300 mg/day (benznidazole increasing dose scheme (BID)).

RESULTS

471 patients were analysed: 201 in the BSD group and 270 in the BID group. There were no significant differences regarding age (40.4 (SD 8.7) vs 41 (SD 8.2) years), sex (74.1% (149/201) vs 68.5% (185/270) women), weight (69.4 (SD 12.8) vs 68.9 (SD 11) kg) or nationality (97.5% (196/201) vs 96.7% (261/270) Bolivians) between groups. There were also no differences in adverse reactions rate (55.2% (111/201) vs 55.6% (150/270)), number of adverse reactions per patient, adverse reactions type (except for arthralgias and myalgias which occurred more frequently in the BID group (0% (0/111) BSD vs 8% (12/150) BID; p 0.002)) and degree and time to first adverse reactions. There was significantly more treatment discontinuation (49.8% (100/201) vs 33.0% (89/270); p <0.001) in the BSD group, but not during the first 30 days of treatment (32.3% (65/201) vs 25.6% (69/270); p 0.08).

CONCLUSION

The use of increasing doses of benznidazole for 5 days and a maximum dose of 300 mg, does not significantly improve drug tolerability. However, while the treatment discontinuation rates were similar during the first 30 days of treatment, it may improve the treatment completion rate at 60 days.

Identification of Phenylpyrazolone Dimers as a New Class of Anti-Trypanosoma cruzi Agents

Chagas disease is becoming a worldwide problem; it is currently estimated that over six million people are infected. The two drugs in current use, benznidazole and nifurtimox, require long treatment regimens, show limited efficacy in the chronic phase of infection, and are known to cause adverse effects. Phenotypic screening of an in-house library led to the identification of 2,2'-methylenebis(5-(4-bromophenyl)-4,4-dimethyl-2,4-dihydro-3H-pyrazol-3-one), a phenyldihydropyrazolone dimer, which shows an in vitro pIC50 value of 5.4 against Trypanosoma cruzi. Initial optimization was done by varying substituents of the phenyl ring, after which attempts were made to replace the phenyl ring. Finally, the linker between the dimer units was varied, ultimately leading to 2,2'-methylenebis(5-(3-bromo-4-methoxyphenyl)-4,4-dimethyl-2,4-dihydro-3H-pyrazol-3-one (NPD-0228) as the most potent analogue. NPD-0228 has an in vitro pIC50 value of 6.4 against intracellular amastigotes of T. cruzi and no apparent toxicity against the human MRC-5 cell line and murine cardiac cells.

Nifurtimox versus benznidazole or placebo for asymptomatic Trypanosoma cruzi infection (Equivalence of Usual Interventions for Trypanosomiasis - EQUITY): study protocol for a randomised controlled trial

Background

Either benznidazole (BZN) or nifurtimox (NFX) is recommended as equivalent to treat Trypanosoma cruzi infection. Nonetheless, supportive data from randomised trials is limited to individuals treated with BZN in southern cone countries of Latin America.

Methods

The goal of this randomised, concealed, blind, parallel-group trial is to inform the trypanocidal efficacy and safety of NFX and its equivalence to BZN among individuals with T. cruzi positive serology (TC+). Eligible individuals are TC+, 20–65 years old, with no apparent symptoms/signs or uncontrolled risk factors for cardiomyopathy and at negligible risk of re-infection. Consenting individuals (adherent to a 10-day placebo run-in phase) receive a 120-day BID blinded treatment with NFX, BZN or matching placebo (2:2:1 ratio). The four active medication arms include (1) a randomly allocated sequence of 60-day, conventional-dose (60CD) regimes (BZN 300 mg/day or NFX 480 mg/day, ratio 1:1), followed or preceded by a 60-day placebo treatment, or (2) 120-day half-dose (120HD) regimes (BZN 150 mg/day or NFX 240 mg/day, ratio 1:1). The primary efficacy outcome is the proportion of participants testing positive at least once for up to three polymerase chain reaction (PCR) assays (1 + PCR) 12–18 months after randomisation. A composite safety outcome includes moderate to severe adverse reactions, consistent blood marker abnormalities or treatment abandons. The trial outside Colombia (expected to recruit at least 60% of participants) is pragmatic; it may be open-label and not include all treatment groups, but it must adhere to the randomisation and data administration system and guarantee a blinded efficacy outcome evaluation. Our main comparisons include NFX groups with placebo (for superiority), NFX versus BZN groups and 60CD versus 120HD groups (for non-inferiority) and testing for the agent-dose and group-region interactions. Assuming a 1 + PCR ≥ 75% in the placebo group, up to 25% among BZN-treated and an absolute difference of up to ≥ 25% with NFX to claim its trypanocidal effect, 60–80 participants per group (at least 300 from Colombia) are needed to test our hypotheses (80–90% power; one-sided alpha level 1%).

Discussion

The EQUITY trial will inform the trypanocidal effect and equivalence of nitroderivative agents NFX and BZN, particularly outside southern cone countries. Its results may challenge current recommendations and inform choices for these agents.

Trial registration

ClinicalTrials.gov, NCT02369978. Registered on 24 February 2015.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3423-3) contains supplementary material, which is available to authorized users.

IL-10/STAT3/SOCS3 Axis Is Involved in the Anti-inflammatory Effect of Benznidazole

Anti-parasitic treatment for Chagas disease mainly relies on benznidazole, which is virtually the only drug available in the market. Besides its anti-parasitic effects, benznidazole has anti-inflammatory properties. In this work we studied the mechanisms involved in the latter, demonstrating the participation of the IL-10/STAT3/SOCS3 pathway. To achieve this goal, the anti-inflammatory properties of benznidazole were studied using an in vitro model of cardiomyocyte primary culture stimulated with LPS. LPS increased both SOCS3 expression and STAT3 phosphorylation. The addition of benznidazole increased their expression even further. Specific inhibition of STAT3 precluded this effect, suggesting a role for STAT3 in the increase of SOCS3 expression induced by benznidazole. To assess the participation of SOCS3 in the anti-inflammatory effect of benznidazole, we accomplished specific knockdown of SOCS3 with siRNA. Silencing of SOCS3 in cardiomyocytes precluded the inhibitory effects of benznidazole on TNF-α, IL-6, iNOS expression and NO release. Moreover, in the absence of SOCS3, benznidazole could neither prevent IKK phosphorylation nor IκBα degradation, supporting the notion that SOCS3 is required for the benznidazole-mediated inhibition of the NF-κB pathway. Previously, we demonstrated that IL-10 increases the expression of SOCS3 in cultured cardiomyocytes. Here, we found that benznidazole shows a trend to increased IL-10 expression. To evaluate whether benznidazole increased SOCS3 in an IL-10-dependent manner, cardiomyocytes from IL-10 knockout mice were pre-treated with benznidazole and stimulated with LPS. Benznidazole neither inhibited NO release nor avoid IKK phosphorylation or IκBα degradation, showing that IL-10 is required for benznidazole-mediated inhibition of NF-κB. Moreover, exogenous addition of IL-10 to IL-10 knockout cardiomyocytes restored the inhibitory effect of benznidazole on NO release. The results reported herein show, for the first time, that the IL-10/STAT3/SOCS3 axis is involved in the anti-inflammatory effects of benznidazole. These findings may add up to new therapeutic strategies for chronic Chagas disease given its inflammatory nature.

Synergic Effect of Allopurinol in Combination with Nitroheterocyclic Compounds against Trypanosoma cruzi

Combination therapy has gained attention as a possible strategy for overcoming the limitations of the present therapeutic arsenal for Chagas disease. The aim of this study was to evaluate the effect of allopurinol in association with nitroheterocyclic compounds on infection with the Y strain of Trypanosoma cruzi The in vitro effect of allopurinol plus benznidazole or nifurtimox on intracellular amastigotes in infected H9c2 cells was assessed in a 72-h assay. The interactions were classified as synergic for both allopurinol-nifurtimox (sums of fractional inhibitory concentrations [∑FICs] = 0.49 ± 0.08) and allopurinol-benznidazole (∑FICs = 0.48 ± 0.09). In the next step, infected Swiss mice were treated with allopurinol at 30, 60, and 90 mg/kg of body weight and with benznidazole at 25, 50, and 75 mg/kg in monotherapy and in combination at the same doses; as a reference treatment, another group of animals received benznidazole at 100 mg/kg. Allopurinol in monotherapy led to a smaller or nil effect in the reduction of parasite load and mortality rate. Treatment with benznidazole at suboptimal doses induced a transient suppression of parasitaemia with subsequent relapse in all animals treated with 25 and 50 mg/kg and in 80% of those that received 75 mg/kg. Administration of the drugs in combination significantly increased the cure rate to 60 to 100% among mice treated with benznidazole at 75 mg/kg plus 30, 60, or 90 mg/kg of allopurinol. These results show a positive interaction between allopurinol and benznidazole, and since both drugs are commercially available, their use in combination may be considered for the assessment in the treatment of Chagas disease patients.