Drugs in preclinical and early clinical development for the treatment of Chagas´s disease: the current status.

INTRODUCTION: Chagas disease is spreading faster than expected in different countries, and little progress has been reported in the discovery of new drugs to combat Trypanosoma cruzi infection in humans. Recent clinical trials have ended with small hope. The pathophysiology of this neglected disease and the genetic diversity of parasites are exceptionally complex. The only two drugs available to treat patients are far from being safe, and their efficacy in the chronic phase is still unsatisfactory. AREAS COVERED: This review offers a comprehensive examination and critical review of data reported in the last 10 years, and it is focused on findings of clinical trials and data acquired in vivo in preclinical studies. EXPERT OPINION: The in vivo investigations classically in mice and dog models are also challenging and time-consuming to attest cure for infection. Poorly standardized protocols, availability of diagnosis methods and disease progression markers, the use of different T. cruzi strains with variable benznidazole sensitivities, and animals in different acute and chronic phases of infection contribute to it. More synchronized efforts between research groups in this field are required to put in evidence new promising substances, drug combinations, repurposing strategies, and new pharmaceutical formulations to impact the therapy.

Lychnopholide loaded in surface modified polylactide nanocapsules (LYC-PLA-PEG-NC) cure mice infected by Trypanosoma cruzi strain a prototype of resistance to benznidazole and nifurtimox: First insights of its mechanism of action.

Chagas disease (CD) remains neglected and causes high morbidity and mortality. The great difficulty is the lack of effective treatment. The current drugs cause side effects and have limited therapeutic efficacy in the chronic phase. This study aims to fulfil some gaps in studies of the natural substance lychnopholide nanoencapsulated LYC-PLA-PEG-NC (LYC-NC) and free (Free-LYC): the activity in epimastigotes and amastigotes to determine its selectivity index (SI), the therapeutic efficacy in mice infected with Colombian Trypanosoma cruzi strain and insight of the mechanism of LYC-NC action on T. cruzi. The SI was obtained by calculation of the ratio between the IC50 value toward H9c2 cells divided by the IC50 value in the anti-T. cruzi test. Infected Swiss mice were treated with 2 and 12 mg/kg/day via intravenous and oral, respectively, and the therapeutic efficacy was determined. The IC50 of LYC-NC and Free-LYC for epimastigotes of T. cruzi were similar. Both were active against amastigotes in cell culture, particularly Free-LYC. The SI of LYC-NC and Free-LYC were 45.38 and 32.11, respectively. LYC-NC 2 and 12 mg/kg/day cured parasitologically, 62.5% and 80% of the animals, respectively, infected with a strain resistant to treatment. The fluorescent NC was distributed in the cardiomyocyte cytoplasm, infected or not, and interacted with the trypomastigotes. Together, these results represent advances in demonstrating LYC as a potent new therapeutic option for treating CD.

Benznidazole, itraconazole, and their combination for the treatment of chronic experimental Chagas disease in dogs.

Treatment for Chagas disease has limited efficacy in the chronic phase. We evaluated benznidazole (BZ) and itraconazole (ITZ) individually and in association in dogs 16 months after infection with a BZ-resistant Trypanosoma cruzi strain. Four study groups (20 animals) were evaluated and treated for 60 days with BZ, ITZ, or BZ + ITZ, and maintained in parallel to control group infected and not treated (INT). All dogs were evaluated in the first, sixth, 12th, 18th and 24th months of study. Polymerase chain reaction (PCR) was negative in 2 of 3 animals in the BZ + ITZ group, 2 of 5 in the BZ group, and 4 of 5 in the ITZ group. Hemoculture performed in the 24th month was negative in all groups. Enzyme-linked immunoassay remained reactive in all treated animals. Echocardiography differentiated treated animals from control animals. Quantitative PCR analysis of cardiac tissue was negative in the BZ + ITZ and BZ groups, positive in 2 of 5 dogs in the ITZ group and in 2 of 3 dogs in the control group, but negative in colon tissue in all groups. Inflammation was significantly reduced in the right atrium and left ventricle of dogs treated with BZ + ITZ and BZ compared with those receiving ITZ alone. Fibrosis was absent in most dogs treated with BZ + ITZ, mild in those treated with BZ or ITZ alone, and intense in the control group. Parasitological and histopathological evaluations showed that BZ + ITZ treatment improved or stabilized the clinical condition of the dogs.

Evaluation of the anti-Trypanosoma cruzi activity in vitro and in vivo of silibinin and silibinin in association to benznidazole.

Chagas disease (CD) is endemic in Latin America. Drugs available for its treatment are benznidazole (BZ)/nifurtimox (NF), both with low efficacy in the late infection and responsible for several side effects. Studies of new drugs for CD among natural products, and using drug combinations with BZ/NF are recommended. Silibinin (SLB) is a natural compound that inhibits the efflux pump (Pgp) of drugs in host cell membranes, causes death of trypanosomatids, has anti-inflammatory activity, and was never assayed against T. cruzi. Here, in vitro and in vivo activities of SLB, SLB+BZ, and BZ against T. cruzi Y strain were evaluated. Cytotoxicity of SLB in VERO cells by the MTT method revealed IC50 of 250.22 µM. The trypanocidal activity evaluated by resazurin method in epimastigotes showed that SLB 25 µM inhibited parasite growth. SLB IC50 and selectivity index (SI) for amastigote were 79.81 µM and 3.13, respectively. SLB100+BZ10 showed higher parasite inhibition (91.44%) than SLB or BZ. Swiss mice infected with Y strain were treated with SLB, SLB+BZ, and BZ. Parasitemia was evaluated daily and 90, 180, and 240 days after treatment in surviving animals by hemoculture, blood qPCR, and after euthanasia, by qPCR in heart tissue. SLB monotherapy was not able to control the parasitemia/mortality of the animals. Parasitological negativation of 85.7-100% was observed in the experimental groups treated with SLB+BZ. Although SLB had shown activity against T. cruzi in vitro, it was not active in mice. Thus, the results of the therapeutic effect observed with SLB+BZ may be interpreted as a result from BZ action.

Benznidazole, itraconazole and their combination in the treatment of acute experimental chagas disease in dogs.

Chagas disease (CD) is a serious public health problem in Latin America and its treatment remains neglected. Benznidazole (BZ), the only drug available in Brazil, presents serious side effects and low therapeutic efficacy, especially at the chronic phase. The last clinical trials demonstrated that the first generation of azole compounds were less successful than BZ in CD chemotherapy, which stimulated studies of these compounds associated to BZ and nifurtimox (NF). This study evaluated the therapeutic efficacy of BZ, itraconazole (ITZ) and their combination (BZ + ITZ) in dogs infected with the VL-10 T. cruzi strain in the acute phase of the disease. Twenty young mongrel dogs were inoculated with 2.0 × 103 blood trypomastigotes/kg and divided into four groups: treated with BZ, ITZ and BZ + ITZ for 60 days, and control group (INT). The parasitemia of the BZ + ITZ and BZ groups were similar and showed significant reduction compared to the INT group. The group treated with ITZ also showed significant parasitemia reduction compared to the INT group. The global analysis of hemoculture (HC), blood PCR, conventional serology (CS-ELISA), heart qPCR and histopathology techniques, used in the post-treatment evaluation, revealed that BZ + ITZ combination lead to a more reduction of parasitemia during the acute phase and heart qPCR positivity, less cardiac damage (inflammation and fibrosis in the left ventricle) and total survival. According to the classical cure criteria one animal treated with BZ + ITZ can be considered cured in its final evaluation and two other dogs, one of this group and one treated with ITZ were in process of cure. At least for BZ-resistant T. cruzi strains such as VL-10, BZ + ITZ was not effective to induce parasitological cure or a profound and sustained reduction of the parasite burden in blood and infected organs.

Benznidazole, itraconazole and their combination in the treatment of acute experimental Chagas disease in dogs.

Chagas disease (CD) is a serious public health problem in Latin America and its treatment remains neglected. Benznidazole (BZ) available in Brazil, presents serious side effects and low therapeutic efficacy at chronic phase. This study evaluated the therapeutic efficacy of BZ, itraconazole (ITZ) and BZ + ITZ in dogs infected with VL-10 T. cruzi strain in the acute phase (Ethic protocol number 2013/28). Twenty young mongrel dogs were inoculated with 2.0 × 103 blood trypomastigotes/kg and divided into four groups: treated with BZ, ITZ and BZ + ITZ for 60 days, and control group (INT-infected not treated). The parasitemia of the BZ + ITZ and BZ groups were similar and showed significant reduction compared to the INT group. The ITZ group also showed significant parasitemia reduction compared to the INT group. For cure control the global analysis of hemoculture (HC), blood PCR, conventional serology (CS-ELISA), heart qPCR and histopathology revealed that BZ + ITZ lead to more reduction of parasitemia during the acute phase and heart qPCR positivity, less cardiac damage and total survival than BZ or ITZ. Moreover, two other dogs, one treated with ITZ and other treated with BZ + ITZ, were always negative in all parasitological tests what indicates parasitological cure or that these dogs are in process of cure. •BZ + ITZ lead to more reduction of parasitemia, total survival, less heart qPCR positivity and cardiac damage.•According to the classic cure criterion cure was observed only in one dog submitted to BZ + ITZ treatment.•Two dogs, one treated with ITZ and other treated with BZ + ITZ were always parasitologically negative.