Published by the International Society of Protistologists
The Journal of
Eukaryotic Microbiology
Journal of Eukaryotic Microbiology ISSN 1066-5234
REVIEW ARTICLE
Recent Clinical Trials for the Etiological Treatment of Chronic Chagas Disease: Advances, Challenges and Perspectives Julio A. Urbina Venezuelan Institute for Scientific Research, Caracas, Venezuela
Keywords Adverse side effects; antiparasitic; benznidazole; efficacy; posaconazole; randomized trial; ravuconazole; Trypanosoma cruzi. Correspondence J.A. Urbina, 200 Lakeside Drive # 503, Oakland, CA 94612, USA Telephone number: +1-513-4072673; FAX number: +1-510-918-4665; e-mail: [email protected] Received: 21 August 2014; revised 18 September 2014; accepted September 18, 2014. doi:10.1111/jeu.12184
ABSTRACT Chagas disease, a chronic systemic parasitosis caused by the Kinetoplastid protozoon Trypanosoma cruzi, is the first cause of cardiac morbidity and mortality in poor rural and suburban areas of Latin America and the largest parasitic disease burden in the continent, now spreading worldwide due to international migrations. A recent change in the scientific paradigm on the pathogenesis of chronic Chagas disease has led to a consensus that all T. cruzi-seropositive patients should receive etiological treatment. This important scientific advance has spurred the rigorous evaluation of the safety and efficacy of currently available drugs (benznidazole and nifurtimox) as well as novel antiT. cruzi drug candidates in chronic patients, who were previously excluded from such treatment. The first results indicate that benznidazole is effective in inducing a marked and sustained reduction in the circulating parasites’ level in the majority of these patients, but adverse effects can lead to treatment discontinuation in 10–20% of cases. Ergosterol biosynthesis inhibitors, such as posaconazole and ravuconazole, are better tolerated but their efficacy at the doses and treatment duration used in the initial studies was significantly lower; such results are probably related to suboptimal exposure and/or treatment duration. Combination therapies are a promising perspective but the lack of validated biomarkers of response to etiological treatment and eventual parasitological cures in chronic patients remains a serious challenge.
AMERICAN Trypanosomiasis, commonly known as Chagas disease in honor of Carlos Chagas, a Brazilian physician who made its first scientific characterization in 1909 (Chagas 1911), is a chronic systemic parasitosis caused by the Kinetoplastid protozoon Trypanosoma cruzi that has afflicted humanity since its earliest presence in the New World (Aufderheide et al. 2004) and remains the largest parasitic disease burden of the American continent, with an estimated global burden of 7.2 billion $ per year (Hotez et al. 2008; Lee et al. 2013; Tarleton et al. 2007). The disease is technically a zoonosis, as the natural reservoirs of T. cruzi are a large variety of marsupial and placental mammals autochthonous to the American continent, the parasite being naturally transmitted by hematophagous Reduviid insects (Gurtler et al. 2008; Reithinger et al. 2009; Tarleton et al. 2007). Human disease results from the invasion of natural ecotopes as well as from the establishment of the vectors in human dwellings due to the poor socio-economic conditions of most rural human
populations from Mexico to Argentina, where the disease is endemic (Gurtler et al. 2008; Reithinger et al. 2009; Tarleton et al. 2007). The parasite can also be transmitted orally by the ingestion of contaminated food, by transfusion or transplant of contaminated blood/organs and congenitally from infected mothers to newborns; the last three routes of transmission, together with intense international migrations in the last 15 yr have led to the spread of the disease to nonendemic areas, such as the US, Western Europe, Australia and Japan (Franco-Paredes et al. 2009; Gascon et al. 2010; Tarleton et al. 2007). Chagas disease is a complex condition resulting from the invasion and successful establishment of T. cruzi, an intracellular parasite, in key tissues of its mammalian hosts. In humans, the initial acute phase has a low (< 10%) mortality and generally mild and unspecific symptoms; macrophages, IFN-gamma, CD4+ and CD8+ Th1 lymphocytes are the key elements controlling parasite replication (Brener and Gazzinelli 1997; Padilla et al. 2009).
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This acute phase is followed by a lifelong chronic condition, where the cellular immune response limits the parasite’s proliferation but is unable to eradicate the infection, leading to a sustained inflammatory response that underlies the development of one or more of the symptomatic chronic forms of the disease in 30–40% of patients, including chronic Chagas cardiomyopathy (CCC), digestive problems and neuropathies (Gutierrez et al. 2009; MarinNeto et al. 2007; Rassi et al. 2000). The most severe of these manifestations is CCC, which typically appears decades after the initial infection, and may result in cardiac arrhythmias, ventricular aneurysm, congestive heart failure, thrombo-embolism, and sudden cardiac death. This condition is the first infectious cardiac disease in the world and the leading cause of cardiac disease and cardiac death in poor rural and rural-originated urban populations in Latin America (Rassi et al. 2000, 2009). Given its zoonotic character, this disease is not eradicable but significant advances have taken place in the control of the vectorial and transfusional transmission of the disease in some parts of the American continent, particularly by the Southern Cone initiative, which led to a significant drop in the prevalence and the population at risk (Gurtler et al. 2008; Reithinger et al. 2009; Tarleton et al. 2007). Nevertheless, the disease is far from being controlled, due to the uneven extent and quality of control programs in other parts of the continent and limitations of both diagnostic methods and currently available specific treatments (Gurtler et al. 2008; Reithinger et al. 2009; Tarleton et al. 2007; Urbina 2010a,b). Unfortunately, due to the complexity of the interactions between this sophisticated parasite and the immune system of its mammalian hosts, an effective prophylactic vaccine has yet to be developed, although some recent results look promising (Beaumier et al. 2013). Etiological treatment of Chagas disease is currently based on two nitroheterocyclic compounds, nifurtimox (a 5-nitrofuran), and benznidazole (a 2-nitromidazole) which were developed empirically over 40 yr ago (Cerisola 1977). Both drugs have significant activity in congenital and adult acute T. cruzi infections (> 95 and 60–80% of parasitological cures, respectively, as defined by negativization of all parasitological and conventional serological tests, as well as in early chronic infections, with 60–70% radical parasitological cures observed among children up to 14 yr old in Brazil and Argentina after several years of follow up (reviewed in Urbina 2010a,b). One important caveat is that efficacy varies according to the geographical area, probably due to differences in drug susceptibility among different T. cruzi strains (Filardi and Brener 1987; Urbina 2010a, b). However, a major limitation of these drugs is their limited and variable curative activity in the established chronic form of the disease, the most prevalent clinical presentation. Although there are no validated biomarkers of parasitological cure in adult chronic patients (see below), ≥ 80% of treated patients are not parasitologically cured according to the classical criteria indicated above for acute infections (reviewed in Urbina 2010a,b). These results have been confirmed using recently developed PCR-based
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methods (high percentages of benznidazole-treated patients with positive T. cruzi PCR tests in cardiac biop~ez et al. 1999; and variable but very significant sies, see An levels of positive PCR blood tests, see: Aguiar et al. 2012; Britto et al. 2001; Fernandes et al. 2009; Machado-deAssis et al. 2012), as well as by nonconventional serological methods (Galvao et al. 1993; Viotti et al. 2011). Nevertheless, several observational clinical studies have shown that chronic patients subjected to antiparasitic treatment with benznidazole, although not parasitologically cured, had a significant reduction in the occurrence of electrocardiographic changes and a lower frequency of deterioration of their clinical condition (reviewed in Viotti and Vigliano 2007). On the other hand, both drugs have unwanted side effects that can lead to treatment discontinuation in 10–20% of patients and are related to their mechanism of action (generation of nitro-reduction intermediates that lead to oxidative stress for NFX or reductive stress for BZN; see Urbina 2010a,b). Despite these limitations of currently available etiological treatments, it should be pointed out that the main reason that discouraged for decades the treatment of chronic Chagas disease patients was a protracted controversy over the pathogenesis of the disease, which has only recently been settled (Kalil and Cunha-Neto 1996; Tarleton 2001; Urbina 2010a,b) and will be discussed in the next section. THE RELEVANCE OF ETIOLOGICAL TREATMENT OF CHRONIC CHAGAS DISEASE Although the role of T. cruzi in the pathology of the acute phase of Chagas disease and the importance of etiological treatment in that stage has always been widely accepted, the participation of the parasite in the pathogenesis of chronic Chagas disease was the subject of decades of controversies (Gutierrez et al. 2009; Machado et al. 2012; Marin-Neto et al. 2007). Several studies implicated autoimmune phenomena as a primary factor leading to the persistent inflammation associated with chronic Chagas disease pathological manifestations, including CCC (reviewed in Kalil and Cunha-Neto 1996). According to such hypothesis, after the initial infection the parasite triggers an autoimmune response in the host and its persistence should not play a pivotal role in the pathogenesis of the disease; thus, even a successful antiparasitic treatment may not lead to an improvement of the clinical outcome of the patients. In fact, the autoimmune hypothesis of chronic Chagas disease pathogenesis stalled for decades the development of new specific chemotherapeutic approaches for this disease, as antiparasitic treatment in the chronic stage was considered irrelevant (Urbina 1999, 2010a,b). This notion, together with the limited efficacy of currently available drugs in long-term chronic infections, is one of the main factors responsible for the low treatment coverage of this condition (Ribeiro et al. 2009). One very important recent development in this field is that the autoimmune hypothesis has been strongly challenged by the results of many studies, which have
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consistently concluded that the persistence of parasites, coupled with an unbalanced immune response in some individuals that may include autoimmune reactions, is a necessary and sufficient condition for the sustained inflammatory responses that underlie the characteristic lesions of chronic Chagas disease (Gutierrez et al. 2009; Hyland et al. 2007; Machado et al. 2012; Marin-Neto et al. 2007; Tarleton 2001). This new paradigm indicates, in contrast with previous notions, that eradication of T. cruzi may be a prerequisite to arrest the evolution of Chagas disease and avert its irreversible long-term consequences and that this condition must be treated primarily as an infectious, not autoimmune, condition, which implies that etiological treatment should be offered to all seropositive patients (Coura and Borges-Pereira 2011; Urbina 2010a,b; Viotti et al. 2014). Seen from this new perspective, the positive effect of currently available drugs (benznidazole) drugs on the patient’s clinical evolution, despite their inability to eradicate the parasite (Viotti and Vigliano 2007), can be explained by a drug-induced reduction in the parasite load in infected tissues. Based on this paradigm shift, in the last decade a series of clinical studies has been launched to rigorously evaluate the safety and efficacy of currently available and novel anti-T. cruzi drugs in chronic patients, whose initial results will be described in the next section. RECENT CLINICAL TRIALS FOR THE ETIOLOGICAL TREATMENT OF CHRONIC CHAGAS DISEASE: RESULTS AND CHALLENGES A series of randomized clinical studies has been launched in the last decade to evaluate the safety and efficacy of benznidazole and two ergosterol biosynthesis inhibitors, posaconazole and ravuconazole (EBI; originally developed for the prophylaxis and treatment of invasive fungal infections) in chronic Chagas disease patients. The incorporation of EBIs in these studies was prompted by promising preclinical studies with this class of compounds that demonstrated unusual potency and selectivity in vitro against the clinically relevant intracellular amastigote stages of many T. cruzi strains and their capacity to induce radical parasitological cure in murine models of acute and chronic Chagas disease, as well as their activity against nitrofuranand nitroimidazole-resistant T. cruzi strains in vivo, even if the hosts were immunosuppressed (reviewed in Buckner and Urbina 2012; Urbina 2009). It must be pointed out at the onset that currently an important limitation of any study of this kind is the lack of validated biomarkers for the modification of parasite loads and eventual parasitological cures in chronically infected individuals (Pinazo et al. 2014; Tarleton et al. 2007). In adult patients with established chronic T. cruzi infections, evaluation of the efficacy of any given drug in terms of clinical response would require several years or decades of follow up (Cancßado 2002; Rassi et al. 2000, 2009), conventional serology responds slowly to parasite elimination, with the lag time increasing with the duration of the original infection (Cancßado 2002; Gomes et al. 2009; Viotti
et al. 2011) and the levels of circulating parasites are often at or below the limit of the most sensitive direct parasitological methods, such as PCR (Britto et al. 2001; Castro et al. 2002; Coronado et al. 2006). The ongoing and recently completed clinical studies for the evaluation of etiological treatment in chronic Chagas disease patients include the following. BENEFIT Marin-Neto et al. (2009); ClinicalTrials.gov Identifier: NCT00123916; Argentina, Brazil, Bolivia, Colombia, El Salvador: First randomized, double blind, placebo controlled Phase 3 trial on the effects of benznidazole (5 mg/ kg/d, 60 d) on a composite endpoint of death, rescued cardiac arrest, sustained ventricular tachycardia, implant of a pacemaker or implantable cardiac defibrillator, heart failure, stroke or systemic embolism and heart transplant in chronic Chagas disease patients with cardiac compromise (NY Heart Association Class I–III). Follow-up period of 4–8 yr (mean: 6 yr). A concomitant PILOT BENEFIT trial is a randomized, double blind, placebo controlled Phase 3 trial on the effects of benznidazole (5 mg/kg/d, 60 d) on the blood T. cruzi load of chronic Chagas disease patients with cardiac compromise, evaluated by quantitative PCR (qPCR); 60% of the originally randomized patients had positive basal PCR (Morillo 2012). Follow up for both studies to be completed in November 2014 and first results expected in 1Q 2015. TRAENA Riarte (2013); Argentina: Randomized, double blind, placebo controlled Phase 3 trial on the effects of benznidazole (5 mg/kg/d, 60 d) on conventional (c-ELISA), nonconventional (ELISA F29), blood T. cruzi load (qPCR), and clinical evolution of adult chronic Chagas disease patients with or without cardiac compromise (ca. 77% indeterminate patients). Mean follow-up time: 7 yr. Initial results presented at the 62nd Annual Meeting of the American Society for Tropical Medicine and Hygiene, in Washington, DC, November 13–17, 2013. CHAGASAZOL Molina et al. (2014); ClinicalTrials.gov Identifier: NCT01162967; Spain: First randomized, double blind, Phase 2 trial on the safety and efficacy of posaconazole (100 and 400 mg b.i.d., 60 d) and benznidazole (5 mg/kg/d, 60 d) on the blood T. cruzi load in chronic Chagas disease patients without cardiac compromise (indeterminate stage), evaluated by qPCR. Follow-up time: 12 mo. Follow up completed in 2012, first full publication of results in 2014. STOP CHAGAS ClinicalTrials.gov Identifier: NCT01377480; Argentina, Colombia and Mexico: Randomized, double blind, placebo
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controlled Phase 2 trial on the safety and efficacy of posaconazole (400 mg b.i.d., 60 d), benznidazole (200 mg b.i.d. 60 d) and a combination of posaconazole (400 mg b.i.d., 60 d) plus benznidazole (200 mg b.i.d. 60 d) on the blood T. cruzi load of chronic Chagas disease patients without cardiac compromise (indeterminate stage), evaluated by qPCR. Follow-up time: 10 mo. Estimated completion date: January 2015. E1224 Torrico (2013); ClinicalTrials.gov Identifier: NCT01489228; Bolivia: Randomized, double blind, placebo controlled Phase 2 Proof-of-Concept Study on the safety and efficacy of E1224 (a prodrug of ravuconazole, 200 mg/wk and 400 mg/wk, 8 wk; 400 mg/wk, 4 wk) and benznidazole (5 mg/kg/d, 8 wk) on the blood T. cruzi load of in chronic Chagas disease patients without cardiac compromise (indeterminate stage), evaluated by qPCR. Early and late predictors (biomarkers) of sustainable response to treatments were also be evaluated. Follow-up time: 10 mo. Completion date: June 2013. Initial results presented at the 62nd Annual Meeting of the American Society for Tropical Medicine and Hygiene, in Washington, DC, November 13–17, 2013. The publication of the results of the CHAGASAZOL trial (Molina et al. 2014) is the first published rigorous demonstration of high anti-T. cruzi efficacy of benznidazole in adult chronic Chagas disease patients and the first ever study on the anti-T. cruzi activity in humans of the antifungal triazole posaconazole, an ergosterol biosynthesis inhibitor acting at C14a sterol demethylase (CYP51). In this analysis it must be kept in mind, as indicated above, that the antiparasitic efficacy measure used in the study – sustained parasitemia clearance, as indicated by negative qPCR, during the follow-up period – does not imply parasitological cure of the patient, as it only indicates that the circulating parasite levels are below the limit of detection of the method and provides no information on the parasite’s burden in internal organs, where T. cruzi multiplies. The key findings were that among patients who completed benznidazole treatment (5 mg/kg/d for 60 d) 94.1% had sustained parasitemia clearance, while only 10–20% of patients that received posaconazole (100 or 400 mg b.i.d., in its liquid suspension formulation, Noxafilâ (Merck & Co., Inc., Whitehouse Station, NJ), for 60 d) displayed the same result, although in the latter case there was a clear dose– response effect on the time to parasitemia relapse. The results in patients receiving benznidazole treatment are the first demonstration that this drug is capable of inducing a strong and sustained reduction in the circulating parasite load in adult chronic patients, although no demonstration of parasitological cures was obtained. Importantly, such results are consistent with others recently reported such as the TRENA (Riarte 2013) and E1224 (Torrico 2013) trials, but it must also be noted that the levels of sustained parasitemia clearance reported for other studies, with the same dose and treatment duration, are markedly lower (Aguiar et al. 2012; Britto et al. 2001; Fernandes
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et al. 2009; Machado-de-Assis et al. 2012). Sustained parasitemia clearance could plausibly be associated with a drug-induced reduction in the parasite load in internal organs and, according to the parasite persistence hypothesis (see above), with a concomitant decrease in the intensity of the inflammatory process triggered by the parasite in such organs, which may lead to a better clinical outcome of the patients. Such prediction is consistent with the results of the observational (not randomized) studies discussed above (Viotti and Vigliano 2007) and would be rigorously tested with the upcoming results of the BENEFIT trial. Nevertheless, it is noteworthy to compare the treatment efficacy (as defined above) for the patients that completed benznidazole treatment (per-protocol, 94.1%) with that for the total population that initiated treatment (intention-to-treat, 61.6%), the latter including patients lost to follow up or for whom the treatment had to be discontinued due to severe adverse side effects (5/26 = 19.2%). Addressing this issue, a subsequent communication reported the concomitant use of benznidazole with lowdose systemic glucocorticoids to control dermatitis, which is the most frequent adverse side effect encountered with this drug: a cohort of 35 patients who had discontinued benznidazole because of severe dermatitis were re-treated with benznidazole along with prednisone, which led to a marked increase in the tolerability of the drug, but still 28% were unable to complete the treatment (Rassi et al. 2014). These facts should remind that, although benznidazole has now been shown to have significant activity chronic T. cruzi infections, it is a drug with significant toxicity, while no significant adverse side effects or treatment discontinuations occurred in patients treated with posaconazole in the Molina et al. study. On the other hand, the failure of posaconazole to induce sustained parasitemia clearance in chronic Chagas disease patients contrasts with the curative activity induced by the drug in murine models of the disease (Buckner and Urbina 2012; Bustamante et al. 2013; Diniz Lde et al. 2013; Urbina 2009) and is most probably explained by the fact that the plasma exposures –AUC1 – in these patients for the doses used (100–400 mg b.i.d.) were just 10–20% of that measured in mice at the curative dose of 20 mg/kg/d (Nomeir et al. 2000). Although Noxafilâ liquid suspension at 400 mg b.i.d. provides the maximum exposure of posaconazole for this formulation in humans (Ullmann et al. 2006), a novel solid (tablet) formulation has been developed that provides significantly higher and consistent plasma exposure, independent of the concomitant uptake of a high-fat meal (Duarte et al. 2014; Krishna et al. 2012a,b). This novel formulation, currently in advanced clinical trials, should be considered for future re-evaluation of the anti-T. cruzi efficacy of the drug in humans, as monotherapy or in drug combinations (see below). Also, sup-optimal treatment duration (60 d), could be invoked to
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It is unclear how the AUC0-24 values were determined in this study, based on a single determination of plasma levels at steady state (14 d).
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explain the limited efficacy for the drug observed in this study, as it has been reported that a chronic Chagas disease patient, at risk of reactivation due to drug-induced immunosuppression, was parasitologically cured with posaconazole, with the same dose and formulation of the drug used in the Molina et al. study, but given for 90 d (Pinazo et al. 2010). Likewise, pharmacodynamic models derived from the initial results of the E1224 study (Torrico 2013) indicate that extending the treatment duration with E1224 at 400 mg/wk from 8 to 12 wk could lead to an increase in the proportion of patients with permanent blood parasite clearance from ca. 30 to > 90%. Such facts indicate that, in contrast with the case of invasive fungal infections, the dose and duration of treatment for the use of EBI to treat human T. cruzi infections has yet to be optimized. CONCLUSIONS AND PERSPECTIVES The radical change in scientific paradigm in our understanding of the pathogenesis of chronic Chagas disease – from the concept of a primary autoimmune disease triggered by the initial parasitic infection to a chronic inflammatory condition sustained by the persistence of the parasite in its target organs – has profound implications for both the therapeutic conduct in the management of chronic patients, as the new consensus is that all seropositive patients should receive etiological treatment independently of the stage of disease they are in (Viotti et al. 2014), as well as for the control programs in endemic countries, which traditionally have largely focused on control of vectorial and transfusional transmission of the parasite but now must also assume the treatment of all those individuals already living with T. cruzi infections (Urbina 2010b). Among the perspectives that this new paradigm opens are ways to improve the safety and efficacy of currently available drugs for their use in chronic patients, including modifications in the treatment regime such as intermittent treatments (Bustamante et al. 2013), the optimization of dose and treatment duration for the use of EBIs as anti-T. cruzi agents (see above), and the use of combination therapies. Combination therapies have been used for decades in antifungal, antiparasitic, and antiviral therapy, as well as in the treatment of fastidious bacterial infections such as TB, aiming to reduce the dose and/or duration of the treatment with the concomitant reduction of side effects and costs, as well as improvement in the patient’s compliance, to exploit potential synergic effects of concomitant treatments and to forestall the development of drug resistance by the etiological agent. However, this concept has not yet been incorporated in the specific chemotherapeutic management of human Chagas disease, despite the limitations of currently available drugs and the long (30–60 d) treatments involved (Coura and Borges-Pereira 2011; Urbina 2010b). The finding of the CHAGASAZOL trial that posaconazole has a demonstrable, albeit limited (for the dose and treatment duration used in the study) anti-T. cruzi activity implies, as the authors suggest, its potential
to be used in combination therapies. In particular, combinations of antifungal azoles (inhibitors of CYP51) such as posaconazole and ravuconazole with benznidazole are expected to be highly effective, based on the results of pharmacogenomic (Ferraz et al. 2009) and pharmacokinetic (Moreira da Silva et al. 2012) studies. Support for this notion comes from recent studies in animal models of Chagas disease, where it was shown that both concomitant and sequential combinations of benznidazole with posaconazole have synergistic anti-T. cruzi effects (Bustamante et al. 2013; Diniz Lde et al. 2013); the same combination is currently being clinically evaluated in the STOP CHAGAS trial promoted by Merck in Argentina, Colombia and Mexico, whose results are expected in 1Q 2015. Finally, the lack of validated biomarkers of responses to etiological treatments and eventual parasitological cures in chronic patients remains a major challenge for the extension of treatment to all seropositive treatments and for the development of safer and more effective drugs for the treatment of established T. cruzi infections (for a systematic review, see Pinazo et al. 2014). Recent studies in a murine model of chronic Chagas disease have shown that radical parasitological cure (verified by immunosuppression of the treated animals) was consistently associated with the disappearance of specific effector/effector memory (TE/TEM) T cells and the development of a stable central memory (TCM) response (Bustamante et al. 2008). Further work in chronically infected adult human patients led for the first time to the identification of fast and specific T (TE/TEM) cell responses resulting from specific antiparasitic treatment (Laucella et al. 2009); unfortunately, the use of this cellular immunological response for the evaluation of efficacy of etiological treatment in chronic patients is limited by the fact that long-term T. cruzi infection in humans might exhaust long-lived memory T cells (Albareda et al. 2009). On the other hand, nonconventional serological methods, including a recently developed multiplex assay (Cooley et al. 2008), can provide fast, easy to measure, responses to etiological treatments (Andrade et al. 2004; Fernandez-Villegas et al. 2011; Krautz et al. 1995) that correlate with those of “lytic” antibodies, a known marker for active T. cruzi infections in humans (Galvao et al. 1993). A recent and interesting development in this area is the identification of plasma biomarkers of T. cruzi infection, specifically fragments of apolipoprotein A1 and human fibronectin generated by the action of the parasite’s cysteine protease cruzipain in infected patients (Miao et al. 2014; Santamaria et al. 2014). Several of these potential biomarkers plus other novel approaches (brain natriuretic peptide, troponin T, selected prothrombotic factors, as well as apolipoprotein A1), were evaluated in parallel with qPCR in the recently completed E1224/benznidazole trial (Torrico 2013) and the results are widely awaited. LITERATURE CITED Aguiar, C., Batista, A. M., Pavan, T. B., Almeida, E. A., Guariento, M. E., Wanderley, J. S. & Costa, S. C. 2012. Serological profiles
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and evaluation of parasitaemia by PCR and blood culture in individuals chronically infected by Trypanosoma cruzi treated with benzonidazole. Tropical Med. Int. Health, 17(3):368–373. Albareda, M. C., Olivera, G. C., Laucella, S. A., Alvarez, M. G., Fernandez, E. R., Lococo, B., Viotti, R., Tarleton, R. L. & Postan, M. 2009. Chronic human infection with Trypanosoma cruzi drives CD4 + T cells to immune senescence. J. Immunol., 183(6):4103–4108. Andrade, A. L., Martelli, C. M., Oliveira, R. M., Silva, S. A., Aires, A. I., Soussumi, L. M., Covas, D. T., Silva, L. S., Andrade, J. G., Travassos, L. R. & Almeida, I. C. 2004. Short report: benznidazole efficacy among Trypanosoma cruzi-infected adolescents after a six-year follow-up. Am. J. Trop. Med. Hyg., 71(5): 594–597. ~ez, N., Carrasco, H., Parada, H., Crisante, G., Rojas, A., FuenAn mayor, C., Gonzalez, N., Percoco, G., Borges, R., Guevara, P. & Ramirez, J. L. 1999. Myocardial parasite persistence in chronic chagasic patients. Am. J. Trop. Med. Hyg., 60(5):726–732. Aufderheide, A. C., Salo, W., Madden, M., Streitz, J., Buikstra, J., Guhl, F., Arriaza, B., Renier, C., Wittmers, L. E. J., Fornaciari, G. & Allison, M. 2004. A 9,000-year record of Chagas’ disease. Proc. Natl Acad. Sci. USA, 101(7):2034–2039. Beaumier, C. M., Gillespie, P. M., Hotez, P. J. & Bottazzi, M. E. 2013. New vaccines for neglected parasitic diseases and dengue. Transl. Res. 162 (3):144–155. Brener, Z. & Gazzinelli, R. T. 1997. Immunological control of Trypanosoma cruzi infection and pathogenesis of Chagas’ disease. Int. Arch. Allergy Immunol., 114(2):103–110. Britto, C., Silveira, C., Cardoso, M. A., Marques, P., Luquetti, A., Macedo, V. & Fernandes, O. 2001. Parasite persistence in treated chagasic patients revealed by xenodiagnosis and polymerase chain reaction. Mem. Inst. Oswaldo Cruz, 96(6):823–826. Buckner, F. S. & Urbina, J. A. 2012. Recent developments in sterol 14-demethylase inhibitors for Chagas disease. Int. J. Parasitol. Drugs Drug Resist., 2:236–242. Bustamante, J. M., Bixby, L. M. & Tarleton, R. L. 2008. Druginduced cure drives conversion to a stable and protective CD8 + T central memory response in chronic Chagas disease. Nat. Med., 14(5):542–550. Bustamante, J. M., Craft, J. M., Crowe, B. D., Ketchie, S. A. & Tarleton, R. L. 2013. New, combined, and reduced dosing treatment protocols cure Trypanosoma cruzi infection in mice. J. Infect. Dis., 209:150–162. Cancßado, J. R. 2002. Long term evaluation of etiological treatment of Chagas disease with benznidazole. Rev. Inst. Med. Trop. Sao Paulo, 44(1):29–37. Castro, A. M., Luquetti, A. O., Rassi, A., Rassi, G. G., Chiari, E. & Galvao, L. M. 2002. Blood culture and polymerase chain reaction for the diagnosis of the chronic phase of human infection with Trypanosoma cruzi. Parasitol. Res., 88(10):894–900. Cerisola, J. A. 1977. Chemotherapy of Chagas’ infection in man. PAHO Sci. Publ., 347:35–47. Chagas, C. 1911. Nova entidade morbida do homen. Resumo gicos e clınicos. Mem. Inst. Oswaldo greal dos estudos etiolo Cruz, 3:219–275. Cooley, G., Etheridge, R. D., Boehlke, C., Bundy, B., Weatherly, D. B., Minning, T., Haney, M., Postan, M., Laucella, S. & Tarleton, R. L. 2008. High throughput selection of effective serodiagnostics for Trypanosoma cruzi infection. PLoS Negl. Trop. Dis., 2(10):e316. Coronado, X., Zulantay, I., Reyes, E., Apt, W., Venegas, J., Rodriguez, J., Solari, A. & Sanchez, G. 2006. Comparison of Trypanosoma cruzi detection by PCR in blood and dejections of Triatoma infestans fed on patients with chronic Chagas disease. Acta Trop., 98(3):314–317.
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Coura, J. R. & Borges-Pereira, J. 2011. Chronic phase of Chagas disease: why should it be treated? A comprehensive review Mem. Inst. Oswaldo Cruz, 106(6):641–645. Diniz Lde, F., Urbina, J. A., de Andrade, I. M., Mazzeti, A. L., Martins, T. A., Caldas, I. S., Talvani, A., Ribeiro, I. & Bahia, M. T. 2013. Benznidazole and posaconazole in experimental Chagas disease: positive interaction in concomitant and sequential treatments. PLoS Negl. Trop. Dis., 7(8), e2367. pez-Jime nez, J., Cornely, O. A., Laverdiere, M., Duarte, R. F., Lo Helfgott, D., Haider, S., Chandrasekar, P., Langston, A., Perfect, J., Ma, L., van Iersel, M. L., Connelly, N., Kartsonis, N. & Waskin, H. 2014. Phase 1b study of new posaconazole tablet for the prevention of invasive fungal infections in high-risk patients with neutropenia. Antimicrob. Agents Chemother., 58(10):5758– 5765. Fernandes, C. D., Tiecher, F. M., Balbinot, M. M., Liarte, D. B., Scholl, D., Steindel, M. & Romanha, A. 2009. Efficacy of benznidazol treatment for asymptomatic chagasic patients from state of Rio Grande do Sul evaluated during a three years follow-up. Mem. Inst. Oswaldo Cruz, 104(1):27–32. Fernandez-Villegas, A., Pinazo, M. J., Maranon, C., Thomas, M. C., Posada, E., Carrilero, B., Segovia, M., Gascon, J. & Lopez, M. C. 2011. Short-term follow-up of chagasic patients after benznidazole treatment using multiple serological markers. BMC Infect. Dis., 11:206. Ferraz, M. L., Gazzinelli, R. T., Alves, R. O., Urbina, J. A. & Romanha, A. J. 2009. Absence of CD4 + T lymphocytes, CD8 + T lymphocytes, or B lymphocytes has different effects on the efficacy of posaconazole and benznidazole in treatment of experimental acute Trypanosoma cruzi infection. Antimicrob. Agents Chemother., 53(1):174–179. Filardi, L. S. & Brener, Z. 1987. Susceptibility and natural resistance of Trypanosoma cruzi strains to drugs used clinically in Chagas disease. Trans. R. Soc. Trop. Med. Hyg., 81(5):755–759. Franco-Paredes, C., Bottazzi, M. E. & Hotez, P. J. 2009. The unfinished public health agenda of Chagas disease in the era of globalization. PLoS Negl. Trop. Dis., 3(7):e470. Galvao, L. M., Nunes, R. M., Cancado, J. R., Brener, Z. & Krettli, A. U. 1993. Lytic antibody titre as a means of assessing cure after treatment of Chagas disease: a 10 years follow-up study. Trans. R. Soc. Trop. Med. Hyg., 87(2):220–223. Gascon, J., Bern, C. & Pinazo, M. J. 2010. Chagas disease in Spain, the United States and other non-endemic countries. Acta Trop., 115(1–2):22–27. Gomes, Y. M., Lorena, V. M. & Luquetti, A. O. 2009. Diagnosis of Chagas disease: what has been achieved? What remains to be done with regard to diagnosis and follow up studies? Mem. Inst. Oswaldo Cruz, 104(4):115–121. Gurtler, R. E., Diotaiuti, L. & Kitron, U. 2008. Commentary: Chagas disease: 100 years since discovery and lessons for the future. Int. J. Epidemiol., 37(4):698–701. Gutierrez, F. R., Guedes, P. M., Gazzinelli, R. T. & Silva, J. S. 2009. The role of parasite persistence in pathogenesis of Chagas heart disease. Parasite Immunol., 31(11):673– 685. Hotez, P. J., Bottazzi, M. E., Franco-Paredes, C., Ault, S. K. & Periago, M. R. 2008. The neglected tropical diseases of Latin America and the Caribbean: a review of disease burden and distribution and a roadmap for control and elimination. PLoS Negl. Trop. Dis., 2(9):e300. Hyland, K. V., Leon, J. S., Daniels, M. D., Giafis, N., Woods, L. M., Bahk, T. J., Wang, K. & Engman, D. M. 2007. Modulation of autoimmunity by treatment of an infectious disease. Infect. Immun., 75(7):3641–3650.
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Kalil, J. & Cunha-Neto, E. 1996. Autoimmunity in Chagas disease cardiomyopathy: fulfilling the criteria at last? Parasitol. Today, 12(10):396–399. Krautz, G. M., Galvao, L. M., Cancado, J. R., Guevara-Espinoza, A., Ouaissi, A. & Krettli, A. U. 1995. Use of a 24-kilodalton Trypanosoma cruzi recombinant protein to monitor cure of human Chagas’ disease. J. Clin. Microbiol., 33(8):2086–2090. Krishna, G., Ma, L., Martinho, M. & O’Mara, E. 2012a. Singledose phase I study to evaluate the pharmacokinetics of posaconazole in new tablet and capsule formulations relative to oral suspension. Antimicrob. Agents Chemother., 56(8): 4196–4201. Krishna, G., Ma, L., Martinho, M., Preston, R. A. & O’Mara, E. 2012b. A new solid oral tablet formulation of posaconazole: a randomized clinical trial to investigate rising single- and multiple-dose pharmacokinetics and safety in healthy volunteers. J. Antimicrob. Chemother., 67(11):2725–2730. Laucella, S. A., Mazliah, D. P., Bertocchi, G., Alvarez, M. G., Cooley, G., Viotti, R., Albareda, M. C., Lococo, B., Postan, M., Armenti, A. & Tarleton, R. L. 2009. Changes in Trypanosoma cruzi-specific immune responses after treatment: surrogate markers of treatment efficacy. Clin. Infect. Dis., 49(11): 1675–1684. Lee, B. Y., Bacon, K. M., Bottazzi, M. E. & Hotez, P. J. 2013. Global economic burden of Chagas disease: a computational simulation model. Lancet Infect. Dis., 13(4):342–348. Machado, F. S., Tyler, K. M., Brant, F., Esper, L., Teixeira, M. M. & Tanowitz, H. B. 2012. Pathogenesis of Chagas disease: time to move on. Front Biosci. (Elite Ed) 4:1743–1758. Machado-de-Assis, G. F., Silva, A. R., Do Bem, V. A., Bahia, M. ~as, P., Torres, R. T., Martins-Filho, O. A., Dias, J. C., Albajar-Vin M. & Lana, M. 2012. Posttherapeutic cure criteria in Chagas’ disease: conventional serology followed by supplementary serological, parasitological, and molecular tests. Clin. Vaccine Immunol., 19(8), 1283–1291. Marin-Neto, J. A., Cunha-Neto, E., Maciel, B. C. & Simoes, M. V. 2007. Pathogenesis of chronic Chagas heart disease. Circulation, 115(9):1109–1123. Marin-Neto, J. A., Rassi, A.Jr, Avezum, A.Jr, Mattos, A. C., Rassi, A., Morillo, C. A., Sosa-Estani, S. & Yusuf, S. 2009. The BENEFIT trial: testing the hypothesis that trypanocidal therapy is beneficial for patients with chronic Chagas heart disease. Mem. Inst. Oswaldo Cruz, 104(Suppl. 1):319–324. Miao, Q., Santamaria, C., Bailey, D., Genest, J., Ward, B. J. & Ndao, M. 2014. Apolipoprotein A-I truncations in Chagas disease are caused by cruzipain, the major cysteine protease of Trypanosoma cruzi. Am. J. Pathol., 184(4):976–984. mez i Prat, J., Salvador, F., Trevin ~o, B., Sulleiro, E., Molina, I., Go Serre, N., Pou, D., Roure, S., Cabezos, J., Valerio, L., BlancoGrau, A., Sanchez-Montalva, A., Vidal, X. & Pahissa, A., 2014. Randomized trial of posaconazole and benznidazole for chronic Chagas’ disease. N. Engl. J. Med., 370(20),1899–1908. Moreira da Silva, R., Oliveira, L. T., Barcellos, N. M. S., de Souza, J. & de Lana, M. 2012. Preclinical monitoring of drug association in experimental chemotherapy of Chagas’ disease by a new HPLC-UV method. Antimicrob. Agents Chemother., 56 (6):3344–3348. n Estudio Clınico BENEFIT (The Morillo, C. A. 2012. Actualizacio BENznidazole Evaluation For Interrupting Trypanosomiasis). Abstracts, VIII Taller sobre la enfermedad de Chagas importada, Barcelona, Spain, p. 34–39. Nomeir, A. A., Kumari, P., Hilbert, M. J., Gupta, S., Loebenberg, D., Cacciapuoti, A., Hare, R., Miller, G. H., Lin, C. C. & Cayen, M. N. 2000. Pharmacokinetics of SCH 56592, a new azole
broad-spectrum antifungal agent, in mice, rats, rabbits, dogs, and cynomolgus monkeys. Antimicrob. Agents Chemother., 44 (3):727–731. Padilla, A. M., Bustamante, J. M. & Tarleton, R. L. 2009. CD8 + T cells in Trypanosoma cruzi infection. Curr. Opin. Immunol., 21 (4):385–390. Pinazo, M. J., Espinosa, G., Gallego, M., Lopez-Chejade, P. L., Urbina, J. A. & Gascon, J. 2010. Successful treatment with posaconazole of a patient with chronic Chagas disease and systemic lupus erythematosus. Am. J. Trop. Med. Hyg., 82:583–587. Pinazo, M. J., Thomas, M. C., Bua, J., Perrone, A., Schijman, A. G., Viotti, R. J., Ramsey, J. M., Ribeiro, I., Sosa-Estani, S., pez, M. C. & Gascon, J. 2014. Biological markers for evaluatLo ing therapeutic efficacy in Chagas disease, a systematic review. Expert Rev. Anti Infect. Ther., 12(4):479–496. Rassi Jr, A., Dias, J. C., Marin-Neto, J. A. & Rassi, A. 2009. Challenges and opportunities for primary, secondary, and tertiary prevention of Chagas’ disease. Heart, 95(7):524–534. Rassi Jr, A., Rassi, A. & Little, W. C. 2000. Chagas’ heart disease. Clin. Cardiol., 23(12):883–889. Rassi, A., Rassi, A. & Marin-Neto, J. A. 2014. Posaconazole versus benznidazole for chronic Chagas’ disease. N. Engl. J. Med., 371(10):965. Reithinger, R., Tarleton, R. L., Urbina, J. A., Kitron, U. & Gurtler, R. E. 2009. Eliminating Chagas disease: challenges and a roadmap. BMJ, 338:b1283. Riarte, A. TRAENA: Placebo-controlled evaluation of impact of benznidazole treatment on long-term disease progression in adults with chronic Chagas disease. 62nd Annual Meeting of the American 460 Society of Tropical Medicine and Hygiene, November 13–17, 2013, Washington, DC. Ribeiro, I., Sevcsik, A. M., Alves, F., Diap, G., Don, R., Harhay, M. O., Chang, S. & Pecoul, B. 2009. New, improved treatments for Chagas disease: from the R&D pipeline to the patients. PLoS Negl. Trop. Dis., 3(7):e484. Santamaria, C., Chatelain, E., Jackson, Y., Miao, Q., Ward, B. J., Chappuis, F. & Ndao, M. 2014. Serum biomarkers predictive of cure in Chagas disease patients after nifurtimox treatment. BMC Infect. Dis., 14:302. Tarleton, R. L. 2001. Parasite persistence in the aetiology of Chagas disease. Int. J. Parasitol., 31(5–6):550–554. Tarleton, R. L., Reithinger, R., Urbina, J. A., Kitron, U. & Gurtler, R. E. 2007. The challenges of Chagas disease – grim outlook or glimmer of hope. PLoS Med., 4(12):e332. Torrico, F. 2013. E1224 – results of proof of concept clinical trial in patients with chronic indeterminate Chagas disease. 62nd Annual Meeting of the American Society of Tropical Medicine and Hygiene, November 13–17, 2013, Washington, DC. Ullmann, A. J., Cornely, O. A., Burchardt, A., Hachem, R., Kontoyiannis, D. P., Topelt, K., Courtney, R., Wexler, D., Krishna, G., Martinho, M., Corcoran, G. & Raad, I. 2006. Pharmacokinetics, safety, and efficacy of posaconazole in patients with persistent febrile neutropenia or refractory invasive fungal infection. Antimicrob. Agents Chemother., 50(2):658–666. Urbina, J. A. 1999. Chemotherapy of Chagas’ disease: the how and the why. J. Mol. Med., 77:332–338. Urbina, J. A. 2009. Ergosterol biosynthesis and drug development for Chagas disease. Mem. Inst. Oswaldo Cruz, 104(Suppl. 1):311–318. Urbina, J. A. 2010a. Specific chemotherapy of Chagas disease: relevance, current limitations and new approaches. Acta Trop., 115(1–2):55–68.
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Urbina, J. A. 2010b. New insights in Chagas’ disease treatment. Drugs Future, 35(5):409–419. n Noya, B., Araujo-Jorge, T., Grijalva, M. J., Viotti, R., de Alarco pez, M. C., Ramsey, J. M., Ribeiro, I., Schijman, A. Guhl, F., Lo G., Sosa-Estani, S., Torrico, F. & Gascon, J. & Latin American Network for Chagas Disease, NHEPACHA. 2014. Towards a paradigm shift in the treatment of chronic Chagas disease. Antimicrob. Agents Chemother., 58(2), 635–639.
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Viotti, R. & Vigliano, C. 2007. Etiological treatment of chronic Chagas disease: neglected ‘evidence’ by evidence-based medicine. Expert Rev. Anti Infect. Ther., 5(4):717–726. Viotti, R., Vigliano, C., Alvarez, M. G., Lococo, B., Petti, M., Bertocchi, G., Armenti, A., De Rissio, A. M., Cooley, G., Tarleton, R. & Laucella, S. 2011. Impact of aetiological treatment on conventional and multiplex serology in chronic Chagas disease. PLoS Negl. Trop. Dis., 5(9):e1314.
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The Journal of
Eukaryotic Microbiology
Journal of Eukaryotic Microbiology ISSN 1066-5234
REVIEW ARTICLE
Recent Clinical Trials for the Etiological Treatment of Chronic Chagas Disease: Advances, Challenges and Perspectives Julio A. Urbina Venezuelan Institute for Scientific Research, Caracas, Venezuela
Keywords Adverse side effects; antiparasitic; benznidazole; efficacy; posaconazole; randomized trial; ravuconazole; Trypanosoma cruzi. Correspondence J.A. Urbina, 200 Lakeside Drive # 503, Oakland, CA 94612, USA Telephone number: +1-513-4072673; FAX number: +1-510-918-4665; e-mail: [email protected] Received: 21 August 2014; revised 18 September 2014; accepted September 18, 2014. doi:10.1111/jeu.12184
ABSTRACT Chagas disease, a chronic systemic parasitosis caused by the Kinetoplastid protozoon Trypanosoma cruzi, is the first cause of cardiac morbidity and mortality in poor rural and suburban areas of Latin America and the largest parasitic disease burden in the continent, now spreading worldwide due to international migrations. A recent change in the scientific paradigm on the pathogenesis of chronic Chagas disease has led to a consensus that all T. cruzi-seropositive patients should receive etiological treatment. This important scientific advance has spurred the rigorous evaluation of the safety and efficacy of currently available drugs (benznidazole and nifurtimox) as well as novel antiT. cruzi drug candidates in chronic patients, who were previously excluded from such treatment. The first results indicate that benznidazole is effective in inducing a marked and sustained reduction in the circulating parasites’ level in the majority of these patients, but adverse effects can lead to treatment discontinuation in 10–20% of cases. Ergosterol biosynthesis inhibitors, such as posaconazole and ravuconazole, are better tolerated but their efficacy at the doses and treatment duration used in the initial studies was significantly lower; such results are probably related to suboptimal exposure and/or treatment duration. Combination therapies are a promising perspective but the lack of validated biomarkers of response to etiological treatment and eventual parasitological cures in chronic patients remains a serious challenge.
AMERICAN Trypanosomiasis, commonly known as Chagas disease in honor of Carlos Chagas, a Brazilian physician who made its first scientific characterization in 1909 (Chagas 1911), is a chronic systemic parasitosis caused by the Kinetoplastid protozoon Trypanosoma cruzi that has afflicted humanity since its earliest presence in the New World (Aufderheide et al. 2004) and remains the largest parasitic disease burden of the American continent, with an estimated global burden of 7.2 billion $ per year (Hotez et al. 2008; Lee et al. 2013; Tarleton et al. 2007). The disease is technically a zoonosis, as the natural reservoirs of T. cruzi are a large variety of marsupial and placental mammals autochthonous to the American continent, the parasite being naturally transmitted by hematophagous Reduviid insects (Gurtler et al. 2008; Reithinger et al. 2009; Tarleton et al. 2007). Human disease results from the invasion of natural ecotopes as well as from the establishment of the vectors in human dwellings due to the poor socio-economic conditions of most rural human
populations from Mexico to Argentina, where the disease is endemic (Gurtler et al. 2008; Reithinger et al. 2009; Tarleton et al. 2007). The parasite can also be transmitted orally by the ingestion of contaminated food, by transfusion or transplant of contaminated blood/organs and congenitally from infected mothers to newborns; the last three routes of transmission, together with intense international migrations in the last 15 yr have led to the spread of the disease to nonendemic areas, such as the US, Western Europe, Australia and Japan (Franco-Paredes et al. 2009; Gascon et al. 2010; Tarleton et al. 2007). Chagas disease is a complex condition resulting from the invasion and successful establishment of T. cruzi, an intracellular parasite, in key tissues of its mammalian hosts. In humans, the initial acute phase has a low (< 10%) mortality and generally mild and unspecific symptoms; macrophages, IFN-gamma, CD4+ and CD8+ Th1 lymphocytes are the key elements controlling parasite replication (Brener and Gazzinelli 1997; Padilla et al. 2009).
© 2014 The Author(s) Journal of Eukaryotic Microbiology © 2014 International Society of Protistologists Journal of Eukaryotic Microbiology 2014, 0, 1–8
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This acute phase is followed by a lifelong chronic condition, where the cellular immune response limits the parasite’s proliferation but is unable to eradicate the infection, leading to a sustained inflammatory response that underlies the development of one or more of the symptomatic chronic forms of the disease in 30–40% of patients, including chronic Chagas cardiomyopathy (CCC), digestive problems and neuropathies (Gutierrez et al. 2009; MarinNeto et al. 2007; Rassi et al. 2000). The most severe of these manifestations is CCC, which typically appears decades after the initial infection, and may result in cardiac arrhythmias, ventricular aneurysm, congestive heart failure, thrombo-embolism, and sudden cardiac death. This condition is the first infectious cardiac disease in the world and the leading cause of cardiac disease and cardiac death in poor rural and rural-originated urban populations in Latin America (Rassi et al. 2000, 2009). Given its zoonotic character, this disease is not eradicable but significant advances have taken place in the control of the vectorial and transfusional transmission of the disease in some parts of the American continent, particularly by the Southern Cone initiative, which led to a significant drop in the prevalence and the population at risk (Gurtler et al. 2008; Reithinger et al. 2009; Tarleton et al. 2007). Nevertheless, the disease is far from being controlled, due to the uneven extent and quality of control programs in other parts of the continent and limitations of both diagnostic methods and currently available specific treatments (Gurtler et al. 2008; Reithinger et al. 2009; Tarleton et al. 2007; Urbina 2010a,b). Unfortunately, due to the complexity of the interactions between this sophisticated parasite and the immune system of its mammalian hosts, an effective prophylactic vaccine has yet to be developed, although some recent results look promising (Beaumier et al. 2013). Etiological treatment of Chagas disease is currently based on two nitroheterocyclic compounds, nifurtimox (a 5-nitrofuran), and benznidazole (a 2-nitromidazole) which were developed empirically over 40 yr ago (Cerisola 1977). Both drugs have significant activity in congenital and adult acute T. cruzi infections (> 95 and 60–80% of parasitological cures, respectively, as defined by negativization of all parasitological and conventional serological tests, as well as in early chronic infections, with 60–70% radical parasitological cures observed among children up to 14 yr old in Brazil and Argentina after several years of follow up (reviewed in Urbina 2010a,b). One important caveat is that efficacy varies according to the geographical area, probably due to differences in drug susceptibility among different T. cruzi strains (Filardi and Brener 1987; Urbina 2010a, b). However, a major limitation of these drugs is their limited and variable curative activity in the established chronic form of the disease, the most prevalent clinical presentation. Although there are no validated biomarkers of parasitological cure in adult chronic patients (see below), ≥ 80% of treated patients are not parasitologically cured according to the classical criteria indicated above for acute infections (reviewed in Urbina 2010a,b). These results have been confirmed using recently developed PCR-based
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methods (high percentages of benznidazole-treated patients with positive T. cruzi PCR tests in cardiac biop~ez et al. 1999; and variable but very significant sies, see An levels of positive PCR blood tests, see: Aguiar et al. 2012; Britto et al. 2001; Fernandes et al. 2009; Machado-deAssis et al. 2012), as well as by nonconventional serological methods (Galvao et al. 1993; Viotti et al. 2011). Nevertheless, several observational clinical studies have shown that chronic patients subjected to antiparasitic treatment with benznidazole, although not parasitologically cured, had a significant reduction in the occurrence of electrocardiographic changes and a lower frequency of deterioration of their clinical condition (reviewed in Viotti and Vigliano 2007). On the other hand, both drugs have unwanted side effects that can lead to treatment discontinuation in 10–20% of patients and are related to their mechanism of action (generation of nitro-reduction intermediates that lead to oxidative stress for NFX or reductive stress for BZN; see Urbina 2010a,b). Despite these limitations of currently available etiological treatments, it should be pointed out that the main reason that discouraged for decades the treatment of chronic Chagas disease patients was a protracted controversy over the pathogenesis of the disease, which has only recently been settled (Kalil and Cunha-Neto 1996; Tarleton 2001; Urbina 2010a,b) and will be discussed in the next section. THE RELEVANCE OF ETIOLOGICAL TREATMENT OF CHRONIC CHAGAS DISEASE Although the role of T. cruzi in the pathology of the acute phase of Chagas disease and the importance of etiological treatment in that stage has always been widely accepted, the participation of the parasite in the pathogenesis of chronic Chagas disease was the subject of decades of controversies (Gutierrez et al. 2009; Machado et al. 2012; Marin-Neto et al. 2007). Several studies implicated autoimmune phenomena as a primary factor leading to the persistent inflammation associated with chronic Chagas disease pathological manifestations, including CCC (reviewed in Kalil and Cunha-Neto 1996). According to such hypothesis, after the initial infection the parasite triggers an autoimmune response in the host and its persistence should not play a pivotal role in the pathogenesis of the disease; thus, even a successful antiparasitic treatment may not lead to an improvement of the clinical outcome of the patients. In fact, the autoimmune hypothesis of chronic Chagas disease pathogenesis stalled for decades the development of new specific chemotherapeutic approaches for this disease, as antiparasitic treatment in the chronic stage was considered irrelevant (Urbina 1999, 2010a,b). This notion, together with the limited efficacy of currently available drugs in long-term chronic infections, is one of the main factors responsible for the low treatment coverage of this condition (Ribeiro et al. 2009). One very important recent development in this field is that the autoimmune hypothesis has been strongly challenged by the results of many studies, which have
© 2014 The Author(s) Journal of Eukaryotic Microbiology © 2014 International Society of Protistologists Journal of Eukaryotic Microbiology 2014, 0, 1–8
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consistently concluded that the persistence of parasites, coupled with an unbalanced immune response in some individuals that may include autoimmune reactions, is a necessary and sufficient condition for the sustained inflammatory responses that underlie the characteristic lesions of chronic Chagas disease (Gutierrez et al. 2009; Hyland et al. 2007; Machado et al. 2012; Marin-Neto et al. 2007; Tarleton 2001). This new paradigm indicates, in contrast with previous notions, that eradication of T. cruzi may be a prerequisite to arrest the evolution of Chagas disease and avert its irreversible long-term consequences and that this condition must be treated primarily as an infectious, not autoimmune, condition, which implies that etiological treatment should be offered to all seropositive patients (Coura and Borges-Pereira 2011; Urbina 2010a,b; Viotti et al. 2014). Seen from this new perspective, the positive effect of currently available drugs (benznidazole) drugs on the patient’s clinical evolution, despite their inability to eradicate the parasite (Viotti and Vigliano 2007), can be explained by a drug-induced reduction in the parasite load in infected tissues. Based on this paradigm shift, in the last decade a series of clinical studies has been launched to rigorously evaluate the safety and efficacy of currently available and novel anti-T. cruzi drugs in chronic patients, whose initial results will be described in the next section. RECENT CLINICAL TRIALS FOR THE ETIOLOGICAL TREATMENT OF CHRONIC CHAGAS DISEASE: RESULTS AND CHALLENGES A series of randomized clinical studies has been launched in the last decade to evaluate the safety and efficacy of benznidazole and two ergosterol biosynthesis inhibitors, posaconazole and ravuconazole (EBI; originally developed for the prophylaxis and treatment of invasive fungal infections) in chronic Chagas disease patients. The incorporation of EBIs in these studies was prompted by promising preclinical studies with this class of compounds that demonstrated unusual potency and selectivity in vitro against the clinically relevant intracellular amastigote stages of many T. cruzi strains and their capacity to induce radical parasitological cure in murine models of acute and chronic Chagas disease, as well as their activity against nitrofuranand nitroimidazole-resistant T. cruzi strains in vivo, even if the hosts were immunosuppressed (reviewed in Buckner and Urbina 2012; Urbina 2009). It must be pointed out at the onset that currently an important limitation of any study of this kind is the lack of validated biomarkers for the modification of parasite loads and eventual parasitological cures in chronically infected individuals (Pinazo et al. 2014; Tarleton et al. 2007). In adult patients with established chronic T. cruzi infections, evaluation of the efficacy of any given drug in terms of clinical response would require several years or decades of follow up (Cancßado 2002; Rassi et al. 2000, 2009), conventional serology responds slowly to parasite elimination, with the lag time increasing with the duration of the original infection (Cancßado 2002; Gomes et al. 2009; Viotti
et al. 2011) and the levels of circulating parasites are often at or below the limit of the most sensitive direct parasitological methods, such as PCR (Britto et al. 2001; Castro et al. 2002; Coronado et al. 2006). The ongoing and recently completed clinical studies for the evaluation of etiological treatment in chronic Chagas disease patients include the following. BENEFIT Marin-Neto et al. (2009); ClinicalTrials.gov Identifier: NCT00123916; Argentina, Brazil, Bolivia, Colombia, El Salvador: First randomized, double blind, placebo controlled Phase 3 trial on the effects of benznidazole (5 mg/ kg/d, 60 d) on a composite endpoint of death, rescued cardiac arrest, sustained ventricular tachycardia, implant of a pacemaker or implantable cardiac defibrillator, heart failure, stroke or systemic embolism and heart transplant in chronic Chagas disease patients with cardiac compromise (NY Heart Association Class I–III). Follow-up period of 4–8 yr (mean: 6 yr). A concomitant PILOT BENEFIT trial is a randomized, double blind, placebo controlled Phase 3 trial on the effects of benznidazole (5 mg/kg/d, 60 d) on the blood T. cruzi load of chronic Chagas disease patients with cardiac compromise, evaluated by quantitative PCR (qPCR); 60% of the originally randomized patients had positive basal PCR (Morillo 2012). Follow up for both studies to be completed in November 2014 and first results expected in 1Q 2015. TRAENA Riarte (2013); Argentina: Randomized, double blind, placebo controlled Phase 3 trial on the effects of benznidazole (5 mg/kg/d, 60 d) on conventional (c-ELISA), nonconventional (ELISA F29), blood T. cruzi load (qPCR), and clinical evolution of adult chronic Chagas disease patients with or without cardiac compromise (ca. 77% indeterminate patients). Mean follow-up time: 7 yr. Initial results presented at the 62nd Annual Meeting of the American Society for Tropical Medicine and Hygiene, in Washington, DC, November 13–17, 2013. CHAGASAZOL Molina et al. (2014); ClinicalTrials.gov Identifier: NCT01162967; Spain: First randomized, double blind, Phase 2 trial on the safety and efficacy of posaconazole (100 and 400 mg b.i.d., 60 d) and benznidazole (5 mg/kg/d, 60 d) on the blood T. cruzi load in chronic Chagas disease patients without cardiac compromise (indeterminate stage), evaluated by qPCR. Follow-up time: 12 mo. Follow up completed in 2012, first full publication of results in 2014. STOP CHAGAS ClinicalTrials.gov Identifier: NCT01377480; Argentina, Colombia and Mexico: Randomized, double blind, placebo
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controlled Phase 2 trial on the safety and efficacy of posaconazole (400 mg b.i.d., 60 d), benznidazole (200 mg b.i.d. 60 d) and a combination of posaconazole (400 mg b.i.d., 60 d) plus benznidazole (200 mg b.i.d. 60 d) on the blood T. cruzi load of chronic Chagas disease patients without cardiac compromise (indeterminate stage), evaluated by qPCR. Follow-up time: 10 mo. Estimated completion date: January 2015. E1224 Torrico (2013); ClinicalTrials.gov Identifier: NCT01489228; Bolivia: Randomized, double blind, placebo controlled Phase 2 Proof-of-Concept Study on the safety and efficacy of E1224 (a prodrug of ravuconazole, 200 mg/wk and 400 mg/wk, 8 wk; 400 mg/wk, 4 wk) and benznidazole (5 mg/kg/d, 8 wk) on the blood T. cruzi load of in chronic Chagas disease patients without cardiac compromise (indeterminate stage), evaluated by qPCR. Early and late predictors (biomarkers) of sustainable response to treatments were also be evaluated. Follow-up time: 10 mo. Completion date: June 2013. Initial results presented at the 62nd Annual Meeting of the American Society for Tropical Medicine and Hygiene, in Washington, DC, November 13–17, 2013. The publication of the results of the CHAGASAZOL trial (Molina et al. 2014) is the first published rigorous demonstration of high anti-T. cruzi efficacy of benznidazole in adult chronic Chagas disease patients and the first ever study on the anti-T. cruzi activity in humans of the antifungal triazole posaconazole, an ergosterol biosynthesis inhibitor acting at C14a sterol demethylase (CYP51). In this analysis it must be kept in mind, as indicated above, that the antiparasitic efficacy measure used in the study – sustained parasitemia clearance, as indicated by negative qPCR, during the follow-up period – does not imply parasitological cure of the patient, as it only indicates that the circulating parasite levels are below the limit of detection of the method and provides no information on the parasite’s burden in internal organs, where T. cruzi multiplies. The key findings were that among patients who completed benznidazole treatment (5 mg/kg/d for 60 d) 94.1% had sustained parasitemia clearance, while only 10–20% of patients that received posaconazole (100 or 400 mg b.i.d., in its liquid suspension formulation, Noxafilâ (Merck & Co., Inc., Whitehouse Station, NJ), for 60 d) displayed the same result, although in the latter case there was a clear dose– response effect on the time to parasitemia relapse. The results in patients receiving benznidazole treatment are the first demonstration that this drug is capable of inducing a strong and sustained reduction in the circulating parasite load in adult chronic patients, although no demonstration of parasitological cures was obtained. Importantly, such results are consistent with others recently reported such as the TRENA (Riarte 2013) and E1224 (Torrico 2013) trials, but it must also be noted that the levels of sustained parasitemia clearance reported for other studies, with the same dose and treatment duration, are markedly lower (Aguiar et al. 2012; Britto et al. 2001; Fernandes
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et al. 2009; Machado-de-Assis et al. 2012). Sustained parasitemia clearance could plausibly be associated with a drug-induced reduction in the parasite load in internal organs and, according to the parasite persistence hypothesis (see above), with a concomitant decrease in the intensity of the inflammatory process triggered by the parasite in such organs, which may lead to a better clinical outcome of the patients. Such prediction is consistent with the results of the observational (not randomized) studies discussed above (Viotti and Vigliano 2007) and would be rigorously tested with the upcoming results of the BENEFIT trial. Nevertheless, it is noteworthy to compare the treatment efficacy (as defined above) for the patients that completed benznidazole treatment (per-protocol, 94.1%) with that for the total population that initiated treatment (intention-to-treat, 61.6%), the latter including patients lost to follow up or for whom the treatment had to be discontinued due to severe adverse side effects (5/26 = 19.2%). Addressing this issue, a subsequent communication reported the concomitant use of benznidazole with lowdose systemic glucocorticoids to control dermatitis, which is the most frequent adverse side effect encountered with this drug: a cohort of 35 patients who had discontinued benznidazole because of severe dermatitis were re-treated with benznidazole along with prednisone, which led to a marked increase in the tolerability of the drug, but still 28% were unable to complete the treatment (Rassi et al. 2014). These facts should remind that, although benznidazole has now been shown to have significant activity chronic T. cruzi infections, it is a drug with significant toxicity, while no significant adverse side effects or treatment discontinuations occurred in patients treated with posaconazole in the Molina et al. study. On the other hand, the failure of posaconazole to induce sustained parasitemia clearance in chronic Chagas disease patients contrasts with the curative activity induced by the drug in murine models of the disease (Buckner and Urbina 2012; Bustamante et al. 2013; Diniz Lde et al. 2013; Urbina 2009) and is most probably explained by the fact that the plasma exposures –AUC1 – in these patients for the doses used (100–400 mg b.i.d.) were just 10–20% of that measured in mice at the curative dose of 20 mg/kg/d (Nomeir et al. 2000). Although Noxafilâ liquid suspension at 400 mg b.i.d. provides the maximum exposure of posaconazole for this formulation in humans (Ullmann et al. 2006), a novel solid (tablet) formulation has been developed that provides significantly higher and consistent plasma exposure, independent of the concomitant uptake of a high-fat meal (Duarte et al. 2014; Krishna et al. 2012a,b). This novel formulation, currently in advanced clinical trials, should be considered for future re-evaluation of the anti-T. cruzi efficacy of the drug in humans, as monotherapy or in drug combinations (see below). Also, sup-optimal treatment duration (60 d), could be invoked to
1
It is unclear how the AUC0-24 values were determined in this study, based on a single determination of plasma levels at steady state (14 d).
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explain the limited efficacy for the drug observed in this study, as it has been reported that a chronic Chagas disease patient, at risk of reactivation due to drug-induced immunosuppression, was parasitologically cured with posaconazole, with the same dose and formulation of the drug used in the Molina et al. study, but given for 90 d (Pinazo et al. 2010). Likewise, pharmacodynamic models derived from the initial results of the E1224 study (Torrico 2013) indicate that extending the treatment duration with E1224 at 400 mg/wk from 8 to 12 wk could lead to an increase in the proportion of patients with permanent blood parasite clearance from ca. 30 to > 90%. Such facts indicate that, in contrast with the case of invasive fungal infections, the dose and duration of treatment for the use of EBI to treat human T. cruzi infections has yet to be optimized. CONCLUSIONS AND PERSPECTIVES The radical change in scientific paradigm in our understanding of the pathogenesis of chronic Chagas disease – from the concept of a primary autoimmune disease triggered by the initial parasitic infection to a chronic inflammatory condition sustained by the persistence of the parasite in its target organs – has profound implications for both the therapeutic conduct in the management of chronic patients, as the new consensus is that all seropositive patients should receive etiological treatment independently of the stage of disease they are in (Viotti et al. 2014), as well as for the control programs in endemic countries, which traditionally have largely focused on control of vectorial and transfusional transmission of the parasite but now must also assume the treatment of all those individuals already living with T. cruzi infections (Urbina 2010b). Among the perspectives that this new paradigm opens are ways to improve the safety and efficacy of currently available drugs for their use in chronic patients, including modifications in the treatment regime such as intermittent treatments (Bustamante et al. 2013), the optimization of dose and treatment duration for the use of EBIs as anti-T. cruzi agents (see above), and the use of combination therapies. Combination therapies have been used for decades in antifungal, antiparasitic, and antiviral therapy, as well as in the treatment of fastidious bacterial infections such as TB, aiming to reduce the dose and/or duration of the treatment with the concomitant reduction of side effects and costs, as well as improvement in the patient’s compliance, to exploit potential synergic effects of concomitant treatments and to forestall the development of drug resistance by the etiological agent. However, this concept has not yet been incorporated in the specific chemotherapeutic management of human Chagas disease, despite the limitations of currently available drugs and the long (30–60 d) treatments involved (Coura and Borges-Pereira 2011; Urbina 2010b). The finding of the CHAGASAZOL trial that posaconazole has a demonstrable, albeit limited (for the dose and treatment duration used in the study) anti-T. cruzi activity implies, as the authors suggest, its potential
to be used in combination therapies. In particular, combinations of antifungal azoles (inhibitors of CYP51) such as posaconazole and ravuconazole with benznidazole are expected to be highly effective, based on the results of pharmacogenomic (Ferraz et al. 2009) and pharmacokinetic (Moreira da Silva et al. 2012) studies. Support for this notion comes from recent studies in animal models of Chagas disease, where it was shown that both concomitant and sequential combinations of benznidazole with posaconazole have synergistic anti-T. cruzi effects (Bustamante et al. 2013; Diniz Lde et al. 2013); the same combination is currently being clinically evaluated in the STOP CHAGAS trial promoted by Merck in Argentina, Colombia and Mexico, whose results are expected in 1Q 2015. Finally, the lack of validated biomarkers of responses to etiological treatments and eventual parasitological cures in chronic patients remains a major challenge for the extension of treatment to all seropositive treatments and for the development of safer and more effective drugs for the treatment of established T. cruzi infections (for a systematic review, see Pinazo et al. 2014). Recent studies in a murine model of chronic Chagas disease have shown that radical parasitological cure (verified by immunosuppression of the treated animals) was consistently associated with the disappearance of specific effector/effector memory (TE/TEM) T cells and the development of a stable central memory (TCM) response (Bustamante et al. 2008). Further work in chronically infected adult human patients led for the first time to the identification of fast and specific T (TE/TEM) cell responses resulting from specific antiparasitic treatment (Laucella et al. 2009); unfortunately, the use of this cellular immunological response for the evaluation of efficacy of etiological treatment in chronic patients is limited by the fact that long-term T. cruzi infection in humans might exhaust long-lived memory T cells (Albareda et al. 2009). On the other hand, nonconventional serological methods, including a recently developed multiplex assay (Cooley et al. 2008), can provide fast, easy to measure, responses to etiological treatments (Andrade et al. 2004; Fernandez-Villegas et al. 2011; Krautz et al. 1995) that correlate with those of “lytic” antibodies, a known marker for active T. cruzi infections in humans (Galvao et al. 1993). A recent and interesting development in this area is the identification of plasma biomarkers of T. cruzi infection, specifically fragments of apolipoprotein A1 and human fibronectin generated by the action of the parasite’s cysteine protease cruzipain in infected patients (Miao et al. 2014; Santamaria et al. 2014). Several of these potential biomarkers plus other novel approaches (brain natriuretic peptide, troponin T, selected prothrombotic factors, as well as apolipoprotein A1), were evaluated in parallel with qPCR in the recently completed E1224/benznidazole trial (Torrico 2013) and the results are widely awaited. LITERATURE CITED Aguiar, C., Batista, A. M., Pavan, T. B., Almeida, E. A., Guariento, M. E., Wanderley, J. S. & Costa, S. C. 2012. Serological profiles
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and evaluation of parasitaemia by PCR and blood culture in individuals chronically infected by Trypanosoma cruzi treated with benzonidazole. Tropical Med. Int. Health, 17(3):368–373. Albareda, M. C., Olivera, G. C., Laucella, S. A., Alvarez, M. G., Fernandez, E. R., Lococo, B., Viotti, R., Tarleton, R. L. & Postan, M. 2009. Chronic human infection with Trypanosoma cruzi drives CD4 + T cells to immune senescence. J. Immunol., 183(6):4103–4108. Andrade, A. L., Martelli, C. M., Oliveira, R. M., Silva, S. A., Aires, A. I., Soussumi, L. M., Covas, D. T., Silva, L. S., Andrade, J. G., Travassos, L. R. & Almeida, I. C. 2004. Short report: benznidazole efficacy among Trypanosoma cruzi-infected adolescents after a six-year follow-up. Am. J. Trop. Med. Hyg., 71(5): 594–597. ~ez, N., Carrasco, H., Parada, H., Crisante, G., Rojas, A., FuenAn mayor, C., Gonzalez, N., Percoco, G., Borges, R., Guevara, P. & Ramirez, J. L. 1999. Myocardial parasite persistence in chronic chagasic patients. Am. J. Trop. Med. Hyg., 60(5):726–732. Aufderheide, A. C., Salo, W., Madden, M., Streitz, J., Buikstra, J., Guhl, F., Arriaza, B., Renier, C., Wittmers, L. E. J., Fornaciari, G. & Allison, M. 2004. A 9,000-year record of Chagas’ disease. Proc. Natl Acad. Sci. USA, 101(7):2034–2039. Beaumier, C. M., Gillespie, P. M., Hotez, P. J. & Bottazzi, M. E. 2013. New vaccines for neglected parasitic diseases and dengue. Transl. Res. 162 (3):144–155. Brener, Z. & Gazzinelli, R. T. 1997. Immunological control of Trypanosoma cruzi infection and pathogenesis of Chagas’ disease. Int. Arch. Allergy Immunol., 114(2):103–110. Britto, C., Silveira, C., Cardoso, M. A., Marques, P., Luquetti, A., Macedo, V. & Fernandes, O. 2001. Parasite persistence in treated chagasic patients revealed by xenodiagnosis and polymerase chain reaction. Mem. Inst. Oswaldo Cruz, 96(6):823–826. Buckner, F. S. & Urbina, J. A. 2012. Recent developments in sterol 14-demethylase inhibitors for Chagas disease. Int. J. Parasitol. Drugs Drug Resist., 2:236–242. Bustamante, J. M., Bixby, L. M. & Tarleton, R. L. 2008. Druginduced cure drives conversion to a stable and protective CD8 + T central memory response in chronic Chagas disease. Nat. Med., 14(5):542–550. Bustamante, J. M., Craft, J. M., Crowe, B. D., Ketchie, S. A. & Tarleton, R. L. 2013. New, combined, and reduced dosing treatment protocols cure Trypanosoma cruzi infection in mice. J. Infect. Dis., 209:150–162. Cancßado, J. R. 2002. Long term evaluation of etiological treatment of Chagas disease with benznidazole. Rev. Inst. Med. Trop. Sao Paulo, 44(1):29–37. Castro, A. M., Luquetti, A. O., Rassi, A., Rassi, G. G., Chiari, E. & Galvao, L. M. 2002. Blood culture and polymerase chain reaction for the diagnosis of the chronic phase of human infection with Trypanosoma cruzi. Parasitol. Res., 88(10):894–900. Cerisola, J. A. 1977. Chemotherapy of Chagas’ infection in man. PAHO Sci. Publ., 347:35–47. Chagas, C. 1911. Nova entidade morbida do homen. Resumo gicos e clınicos. Mem. Inst. Oswaldo greal dos estudos etiolo Cruz, 3:219–275. Cooley, G., Etheridge, R. D., Boehlke, C., Bundy, B., Weatherly, D. B., Minning, T., Haney, M., Postan, M., Laucella, S. & Tarleton, R. L. 2008. High throughput selection of effective serodiagnostics for Trypanosoma cruzi infection. PLoS Negl. Trop. Dis., 2(10):e316. Coronado, X., Zulantay, I., Reyes, E., Apt, W., Venegas, J., Rodriguez, J., Solari, A. & Sanchez, G. 2006. Comparison of Trypanosoma cruzi detection by PCR in blood and dejections of Triatoma infestans fed on patients with chronic Chagas disease. Acta Trop., 98(3):314–317.
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Coura, J. R. & Borges-Pereira, J. 2011. Chronic phase of Chagas disease: why should it be treated? A comprehensive review Mem. Inst. Oswaldo Cruz, 106(6):641–645. Diniz Lde, F., Urbina, J. A., de Andrade, I. M., Mazzeti, A. L., Martins, T. A., Caldas, I. S., Talvani, A., Ribeiro, I. & Bahia, M. T. 2013. Benznidazole and posaconazole in experimental Chagas disease: positive interaction in concomitant and sequential treatments. PLoS Negl. Trop. Dis., 7(8), e2367. pez-Jime nez, J., Cornely, O. A., Laverdiere, M., Duarte, R. F., Lo Helfgott, D., Haider, S., Chandrasekar, P., Langston, A., Perfect, J., Ma, L., van Iersel, M. L., Connelly, N., Kartsonis, N. & Waskin, H. 2014. Phase 1b study of new posaconazole tablet for the prevention of invasive fungal infections in high-risk patients with neutropenia. Antimicrob. Agents Chemother., 58(10):5758– 5765. Fernandes, C. D., Tiecher, F. M., Balbinot, M. M., Liarte, D. B., Scholl, D., Steindel, M. & Romanha, A. 2009. Efficacy of benznidazol treatment for asymptomatic chagasic patients from state of Rio Grande do Sul evaluated during a three years follow-up. Mem. Inst. Oswaldo Cruz, 104(1):27–32. Fernandez-Villegas, A., Pinazo, M. J., Maranon, C., Thomas, M. C., Posada, E., Carrilero, B., Segovia, M., Gascon, J. & Lopez, M. C. 2011. Short-term follow-up of chagasic patients after benznidazole treatment using multiple serological markers. BMC Infect. Dis., 11:206. Ferraz, M. L., Gazzinelli, R. T., Alves, R. O., Urbina, J. A. & Romanha, A. J. 2009. Absence of CD4 + T lymphocytes, CD8 + T lymphocytes, or B lymphocytes has different effects on the efficacy of posaconazole and benznidazole in treatment of experimental acute Trypanosoma cruzi infection. Antimicrob. Agents Chemother., 53(1):174–179. Filardi, L. S. & Brener, Z. 1987. Susceptibility and natural resistance of Trypanosoma cruzi strains to drugs used clinically in Chagas disease. Trans. R. Soc. Trop. Med. Hyg., 81(5):755–759. Franco-Paredes, C., Bottazzi, M. E. & Hotez, P. J. 2009. The unfinished public health agenda of Chagas disease in the era of globalization. PLoS Negl. Trop. Dis., 3(7):e470. Galvao, L. M., Nunes, R. M., Cancado, J. R., Brener, Z. & Krettli, A. U. 1993. Lytic antibody titre as a means of assessing cure after treatment of Chagas disease: a 10 years follow-up study. Trans. R. Soc. Trop. Med. Hyg., 87(2):220–223. Gascon, J., Bern, C. & Pinazo, M. J. 2010. Chagas disease in Spain, the United States and other non-endemic countries. Acta Trop., 115(1–2):22–27. Gomes, Y. M., Lorena, V. M. & Luquetti, A. O. 2009. Diagnosis of Chagas disease: what has been achieved? What remains to be done with regard to diagnosis and follow up studies? Mem. Inst. Oswaldo Cruz, 104(4):115–121. Gurtler, R. E., Diotaiuti, L. & Kitron, U. 2008. Commentary: Chagas disease: 100 years since discovery and lessons for the future. Int. J. Epidemiol., 37(4):698–701. Gutierrez, F. R., Guedes, P. M., Gazzinelli, R. T. & Silva, J. S. 2009. The role of parasite persistence in pathogenesis of Chagas heart disease. Parasite Immunol., 31(11):673– 685. Hotez, P. J., Bottazzi, M. E., Franco-Paredes, C., Ault, S. K. & Periago, M. R. 2008. The neglected tropical diseases of Latin America and the Caribbean: a review of disease burden and distribution and a roadmap for control and elimination. PLoS Negl. Trop. Dis., 2(9):e300. Hyland, K. V., Leon, J. S., Daniels, M. D., Giafis, N., Woods, L. M., Bahk, T. J., Wang, K. & Engman, D. M. 2007. Modulation of autoimmunity by treatment of an infectious disease. Infect. Immun., 75(7):3641–3650.
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Urbina
Kalil, J. & Cunha-Neto, E. 1996. Autoimmunity in Chagas disease cardiomyopathy: fulfilling the criteria at last? Parasitol. Today, 12(10):396–399. Krautz, G. M., Galvao, L. M., Cancado, J. R., Guevara-Espinoza, A., Ouaissi, A. & Krettli, A. U. 1995. Use of a 24-kilodalton Trypanosoma cruzi recombinant protein to monitor cure of human Chagas’ disease. J. Clin. Microbiol., 33(8):2086–2090. Krishna, G., Ma, L., Martinho, M. & O’Mara, E. 2012a. Singledose phase I study to evaluate the pharmacokinetics of posaconazole in new tablet and capsule formulations relative to oral suspension. Antimicrob. Agents Chemother., 56(8): 4196–4201. Krishna, G., Ma, L., Martinho, M., Preston, R. A. & O’Mara, E. 2012b. A new solid oral tablet formulation of posaconazole: a randomized clinical trial to investigate rising single- and multiple-dose pharmacokinetics and safety in healthy volunteers. J. Antimicrob. Chemother., 67(11):2725–2730. Laucella, S. A., Mazliah, D. P., Bertocchi, G., Alvarez, M. G., Cooley, G., Viotti, R., Albareda, M. C., Lococo, B., Postan, M., Armenti, A. & Tarleton, R. L. 2009. Changes in Trypanosoma cruzi-specific immune responses after treatment: surrogate markers of treatment efficacy. Clin. Infect. Dis., 49(11): 1675–1684. Lee, B. Y., Bacon, K. M., Bottazzi, M. E. & Hotez, P. J. 2013. Global economic burden of Chagas disease: a computational simulation model. Lancet Infect. Dis., 13(4):342–348. Machado, F. S., Tyler, K. M., Brant, F., Esper, L., Teixeira, M. M. & Tanowitz, H. B. 2012. Pathogenesis of Chagas disease: time to move on. Front Biosci. (Elite Ed) 4:1743–1758. Machado-de-Assis, G. F., Silva, A. R., Do Bem, V. A., Bahia, M. ~as, P., Torres, R. T., Martins-Filho, O. A., Dias, J. C., Albajar-Vin M. & Lana, M. 2012. Posttherapeutic cure criteria in Chagas’ disease: conventional serology followed by supplementary serological, parasitological, and molecular tests. Clin. Vaccine Immunol., 19(8), 1283–1291. Marin-Neto, J. A., Cunha-Neto, E., Maciel, B. C. & Simoes, M. V. 2007. Pathogenesis of chronic Chagas heart disease. Circulation, 115(9):1109–1123. Marin-Neto, J. A., Rassi, A.Jr, Avezum, A.Jr, Mattos, A. C., Rassi, A., Morillo, C. A., Sosa-Estani, S. & Yusuf, S. 2009. The BENEFIT trial: testing the hypothesis that trypanocidal therapy is beneficial for patients with chronic Chagas heart disease. Mem. Inst. Oswaldo Cruz, 104(Suppl. 1):319–324. Miao, Q., Santamaria, C., Bailey, D., Genest, J., Ward, B. J. & Ndao, M. 2014. Apolipoprotein A-I truncations in Chagas disease are caused by cruzipain, the major cysteine protease of Trypanosoma cruzi. Am. J. Pathol., 184(4):976–984. mez i Prat, J., Salvador, F., Trevin ~o, B., Sulleiro, E., Molina, I., Go Serre, N., Pou, D., Roure, S., Cabezos, J., Valerio, L., BlancoGrau, A., Sanchez-Montalva, A., Vidal, X. & Pahissa, A., 2014. Randomized trial of posaconazole and benznidazole for chronic Chagas’ disease. N. Engl. J. Med., 370(20),1899–1908. Moreira da Silva, R., Oliveira, L. T., Barcellos, N. M. S., de Souza, J. & de Lana, M. 2012. Preclinical monitoring of drug association in experimental chemotherapy of Chagas’ disease by a new HPLC-UV method. Antimicrob. Agents Chemother., 56 (6):3344–3348. n Estudio Clınico BENEFIT (The Morillo, C. A. 2012. Actualizacio BENznidazole Evaluation For Interrupting Trypanosomiasis). Abstracts, VIII Taller sobre la enfermedad de Chagas importada, Barcelona, Spain, p. 34–39. Nomeir, A. A., Kumari, P., Hilbert, M. J., Gupta, S., Loebenberg, D., Cacciapuoti, A., Hare, R., Miller, G. H., Lin, C. C. & Cayen, M. N. 2000. Pharmacokinetics of SCH 56592, a new azole
broad-spectrum antifungal agent, in mice, rats, rabbits, dogs, and cynomolgus monkeys. Antimicrob. Agents Chemother., 44 (3):727–731. Padilla, A. M., Bustamante, J. M. & Tarleton, R. L. 2009. CD8 + T cells in Trypanosoma cruzi infection. Curr. Opin. Immunol., 21 (4):385–390. Pinazo, M. J., Espinosa, G., Gallego, M., Lopez-Chejade, P. L., Urbina, J. A. & Gascon, J. 2010. Successful treatment with posaconazole of a patient with chronic Chagas disease and systemic lupus erythematosus. Am. J. Trop. Med. Hyg., 82:583–587. Pinazo, M. J., Thomas, M. C., Bua, J., Perrone, A., Schijman, A. G., Viotti, R. J., Ramsey, J. M., Ribeiro, I., Sosa-Estani, S., pez, M. C. & Gascon, J. 2014. Biological markers for evaluatLo ing therapeutic efficacy in Chagas disease, a systematic review. Expert Rev. Anti Infect. Ther., 12(4):479–496. Rassi Jr, A., Dias, J. C., Marin-Neto, J. A. & Rassi, A. 2009. Challenges and opportunities for primary, secondary, and tertiary prevention of Chagas’ disease. Heart, 95(7):524–534. Rassi Jr, A., Rassi, A. & Little, W. C. 2000. Chagas’ heart disease. Clin. Cardiol., 23(12):883–889. Rassi, A., Rassi, A. & Marin-Neto, J. A. 2014. Posaconazole versus benznidazole for chronic Chagas’ disease. N. Engl. J. Med., 371(10):965. Reithinger, R., Tarleton, R. L., Urbina, J. A., Kitron, U. & Gurtler, R. E. 2009. Eliminating Chagas disease: challenges and a roadmap. BMJ, 338:b1283. Riarte, A. TRAENA: Placebo-controlled evaluation of impact of benznidazole treatment on long-term disease progression in adults with chronic Chagas disease. 62nd Annual Meeting of the American 460 Society of Tropical Medicine and Hygiene, November 13–17, 2013, Washington, DC. Ribeiro, I., Sevcsik, A. M., Alves, F., Diap, G., Don, R., Harhay, M. O., Chang, S. & Pecoul, B. 2009. New, improved treatments for Chagas disease: from the R&D pipeline to the patients. PLoS Negl. Trop. Dis., 3(7):e484. Santamaria, C., Chatelain, E., Jackson, Y., Miao, Q., Ward, B. J., Chappuis, F. & Ndao, M. 2014. Serum biomarkers predictive of cure in Chagas disease patients after nifurtimox treatment. BMC Infect. Dis., 14:302. Tarleton, R. L. 2001. Parasite persistence in the aetiology of Chagas disease. Int. J. Parasitol., 31(5–6):550–554. Tarleton, R. L., Reithinger, R., Urbina, J. A., Kitron, U. & Gurtler, R. E. 2007. The challenges of Chagas disease – grim outlook or glimmer of hope. PLoS Med., 4(12):e332. Torrico, F. 2013. E1224 – results of proof of concept clinical trial in patients with chronic indeterminate Chagas disease. 62nd Annual Meeting of the American Society of Tropical Medicine and Hygiene, November 13–17, 2013, Washington, DC. Ullmann, A. J., Cornely, O. A., Burchardt, A., Hachem, R., Kontoyiannis, D. P., Topelt, K., Courtney, R., Wexler, D., Krishna, G., Martinho, M., Corcoran, G. & Raad, I. 2006. Pharmacokinetics, safety, and efficacy of posaconazole in patients with persistent febrile neutropenia or refractory invasive fungal infection. Antimicrob. Agents Chemother., 50(2):658–666. Urbina, J. A. 1999. Chemotherapy of Chagas’ disease: the how and the why. J. Mol. Med., 77:332–338. Urbina, J. A. 2009. Ergosterol biosynthesis and drug development for Chagas disease. Mem. Inst. Oswaldo Cruz, 104(Suppl. 1):311–318. Urbina, J. A. 2010a. Specific chemotherapy of Chagas disease: relevance, current limitations and new approaches. Acta Trop., 115(1–2):55–68.
© 2014 The Author(s) Journal of Eukaryotic Microbiology © 2014 International Society of Protistologists Journal of Eukaryotic Microbiology 2014, 0, 1–8
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Etiological Treatment of Chronic Chagas Disease
Urbina
Urbina, J. A. 2010b. New insights in Chagas’ disease treatment. Drugs Future, 35(5):409–419. n Noya, B., Araujo-Jorge, T., Grijalva, M. J., Viotti, R., de Alarco pez, M. C., Ramsey, J. M., Ribeiro, I., Schijman, A. Guhl, F., Lo G., Sosa-Estani, S., Torrico, F. & Gascon, J. & Latin American Network for Chagas Disease, NHEPACHA. 2014. Towards a paradigm shift in the treatment of chronic Chagas disease. Antimicrob. Agents Chemother., 58(2), 635–639.
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Viotti, R. & Vigliano, C. 2007. Etiological treatment of chronic Chagas disease: neglected ‘evidence’ by evidence-based medicine. Expert Rev. Anti Infect. Ther., 5(4):717–726. Viotti, R., Vigliano, C., Alvarez, M. G., Lococo, B., Petti, M., Bertocchi, G., Armenti, A., De Rissio, A. M., Cooley, G., Tarleton, R. & Laucella, S. 2011. Impact of aetiological treatment on conventional and multiplex serology in chronic Chagas disease. PLoS Negl. Trop. Dis., 5(9):e1314.
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