Present situation and new strategies for Chagas disease chemotherapy: a proposal

Treatments for Chagas disease have been administered since the first attempts by Mayer & Rocha Lima (1912, 1914) and up to the drugs currently in use (nifurtimox and benznidazole), along with potential drugs such as allopurinol and first, second and third-generation antifungal agents (imidazoles and triazoles), in separate form. Several diseases such as tuberculosis, leprosy and AIDS only came under control after they were treated with associations of drugs with different mechanisms of action. This not only boosts the action of the different compounds, but also may avoid the development of parasite resistance .To this end, over the short term, we propose experimental studies on laboratory animals and clinical trials with the following associations: (i) nifurtimox (8 mg/kg/day) + benznidazole (5 mg/kg/day) x 60 consecutive days; (ii) nifurtimox (8 mg/kg/day) or benznidazole (5 mg/kg/day) + allopurinol (8-10 mg/kg/day) x 60 days and (iii) nifurtimox (8 mg/kg/day) or benznidazole (5 mg/kg/day) + ketoconazole, fluconazole or itraconazole (5-6 mg/kg/day) x 60 consecutive days. The doses of the drugs and the treatment schedules for the clinical trials must be adapted according to the side effects. From these, other double or triple associations could be made, using drugs with different mechanisms of action. This proposal does not exclude investigations on new drugs over the median and long terms, targeting other aspects of the metabolism of Trypanosoma cruzi. Until such time as the ideal drug for specific treatment of Chagas disease might be discovered, we need to develop new strategies for achieving greater efficacy with the old drugs in associations and to develop rational experimentation with new drugs.

Usefulness of PCR-based assays to assess drug efficacy in Chagas disease chemotherapy: value and limitations

One major goal of research on Chagas disease is the development of effective chemotherapy to eliminate the infection from individuals who have not yet developed cardiac and/or digestive disease manifestations. Cure evaluation is the more complex aspect of its treatment, often leading to diverse and controversial results. The absence of reliable methods or a diagnostic gold standard to assess etiologic treatment efficacy still constitutes a major challenge. In an effort to develop more sensitive tools, polymerase chain reaction (PCR)-based assays were introduced to detect low amounts of Trypanosoma cruzi DNA in blood samples from chagasic patients, thus improving the diagnosis and follow-up evaluation after chemotherapy. In this article, I review the main problems concerning drug efficacy and criteria used for cure estimation in treated chagasic patients, and the work conducted by different groups on developing PCR methodologies to monitor treatment outcome of congenital infections as well as recent and late chronic T. cruzi infections.

Experimental chemotherapy for Chagas disease: 15 years of research contributions from in vivo and in vitro studies

Chagas disease, which is caused by the intracellular parasite Trypanosoma cruzi, is a neglected illness with 12-14 million reported cases in endemic geographic regions of Latin America. While the disease still represents an important public health problem in these affected areas, the available therapy, which was introduced more than four decades ago, is far from ideal due to its substantial toxicity, its limited effects on different parasite stocks, and its poor activity during the chronic phase of the disease. For the past 15 years, our group, in collaboration with research groups focused on medicinal chemistry, has been working on experimental chemotherapies for Chagas disease, investigating the biological activity, toxicity, selectivity and cellular targets of different classes of compounds on T. cruzi. In this report, we present an overview of these in vitro and in vivo studies, focusing on the most promising classes of compounds with the aim of contributing to the current knowledge of the treatment of Chagas disease and aiding in the development of a new arsenal of candidates with anti-T. cruzi efficacy.

Antibody reactivity against potato apyrase, a protein that shares epitopes with Schistosoma mansoni ATP diphosphohydrolase isoforms, in acute and chronically infected mice, after chemotherapy and reinfection

Schistosoma mansoni ATP diphosphohydrolase isoforms and potato apyrase share conserved epitopes. By enzyme-linked immunosorbent assays, elevated levels of IgM, IgG2a and IgG1 antibody reactivity against potato apyrase were observed in S. mansoni-infected BALB/c mice during the acute phase of infection, while only IgM and IgG1 antibody reactivity levels maintained elevated during the chronic phase of infection. Antibody reactivity against potato apyrase was monitored over an 11-month period in chronically-infected mice treated with oxamniquine. Eleven months later, the level of seropositive IgM decreased significantly (~30%) compared to the level found in untreated, infected mice. The level of seropositive IgG1 decreased significantly four months after treatment (MAT) (61%) and remained at this level even after 11 months. The IgG2a reactivity against potato apyrase, although unchanged during chronic phase to 11 MAT, appeared elevated again in re-infected mice suggesting a response similar to that found during the acute phase. BALB/c mouse polyclonal anti-potato apyrase IgG reacted with soluble egg antigens probably due to the recognition of parasite ATP diphosphohydrolase. This study, for the first time, showed that the IgG2a antibody from S. mansoni-infected BALB mice cross-reacts with potato apyrase and the level of IgG2a in infected mice differentiates disease phases. The results also suggest that different conserved-epitopes contribute to the immune response in schistosomiasis.

Spatial distribution of Schistosoma mansoni infection before and after chemotherapy with two praziquantel doses in a community of Pernambuco, Brazil

Praziquantel chemotherapy has been the focus of the Schistosomiasis Control Program in Brazil for the past two decades. Nevertheless, information on the impact of selective chemotherapy against Schistosoma mansoni infection under the conditions confronted by the health teams in endemic municipalities remains scarce. This paper compares the spatial pattern of infection before and after treatment with either a 40 mg/kg or 60 mg/kg dose of praziquantel by determining the intensity of spatial cluster among patients at 180 and 360 days after treatment. The spatial-temporal distribution of egg-positive patients was analysed in a Geographic Information System using the kernel smoothing technique. While all patients became egg-negative after 21 days, 17.9% and 30.9% reverted to an egg-positive condition after 180 and 360 days, respectively. Both the prevalence and intensity of infection after treatment were significantly lower in the 60 mg/kg than in the 40 mg/kg treatment group. The higher intensity of the kernel in the 40 mg/kg group compared to the 60 mg/kg group, at both 180 and 360 days, reflects the higher number of reverted cases in the lower dose group. Auxiliary, preventive measures to control transmission should be integrated with chemotherapy to achieve a more enduring impact.

Influence of anti-filarial chemotherapy strategies on the genetic structure of Wuchereria bancrofti populations

Lymphatic filarial (LF) parasites have been under anti-filarial drug pressure for more than half a century. Currently, annual mass drug administration (MDA) of diethylcarbamazine (DEC) or ivermectin in combination with albendazole (ALB) have been used globally to eliminate LF. Long-term chemotherapies exert significant pressure on the genetic structure of parasitic populations. We investigated the genetic variation among 210 Wuchereria bancrofti populations that were under three different chemotherapy strategies, namely MDA with DEC alone (group I, n = 74), MDA with DEC and ALB (group II, n = 60) and selective therapy (ST) with DEC (group III, n = 34) to understand the impact of these three drug regimens on the parasite genetic structure. Randomly amplified polymorphic DNA profiles were generated for the three groups of parasite populations; the gene diversity, gene flow and genetic distance values were determined and phylogenetic trees were constructed. Analysis of these parameters indicated that parasite populations under ST with a standard dose of DEC (group III) were genetically more diverse (0.2660) than parasite populations under MDA with DEC alone (group I, H = 0.2197) or with DEC + ALB (group II, H = 0.2317). These results indicate that the MDA may reduce the genetic diversity of W. bancrofti populations when compared to the genetic diversity of parasite populations under ST.

Vertebral artery occlusion after chemotherapy

We present a patient who experienced a stroke due to vertebral artery occlusion after chemotherapy

Search for a platelet-activating factor receptor in the Trypanosoma cruzi proteome: a potential target for Chagas disease chemotherapy

Chagas disease (CD) causes the highest burden of parasitic diseases in the Western Hemisphere and is therefore a priority for drug research and development. Platelet-activating factor (PAF) causes the CD parasite Trypanosoma cruzi to differentiate, which suggests that the parasite may express PAF receptors. Here, we explored the T. cruzi proteome for PAF receptor-like proteins. From a total of 23,000 protein sequences, we identified 29 hypothetical proteins that are predicted to have seven transmembrane domains (TMDs), which is the main characteristic of the G protein-coupled receptors (GPCRs), including the PAF receptor. The TMDs of these sequences were independently aligned with domains from 25 animal PAF receptors and the sequences were analysed for conserved residues. The conservation score mean values for the TMDs of the hypothetical proteins ranged from 31.7-44.1%, which suggests that if the putative T. cruzi PAF receptor is among the sequences identified, the TMDs are not highly conserved. These results suggest that T. cruzi contains several GPCR-like proteins and that one of these GPCRs may be a PAF receptor. Future studies may further validate the PAF receptor as a target for CD chemotherapy.

Primary renal lymphoma: long-term results of two patients treated with a chemotherapy + rituximab protocol.

Primary renal lymphoma (PRL) is a rare disease of which the etiology and pathogenesis remain controversial, and there is currently no standard treatment for it. We present the results of a long-term followup of two patients who were diagnosed with PRL and treated with cyclophosphamide, adriamycin, vincristine, prednisolone and rituximab (CHOP + R) regimen. Both patients reached a complete response, and there is no evidence of recurrence after 4.5- and 5-year followup periods. Based on our experience and other recently published studies, we recommend the combination of CHOP + rituximab as the elective treatment for this disease. To our knowledge, this is the longest followup period with a complete response that has been reported with this modality of treatment.

Chemotherapy for advanced gastric cancer.

BACKGROUND: Gastric cancer currently ranks second in global cancer mortality. Most patients are either diagnosed at an advanced stage, or develop a relapse after surgery with curative intent. Apart from supportive care and palliative radiation to localized (e.g. bone) metastasis, systemic chemotherapy is the only treatment option available in this situation. OBJECTIVES: To assess the efficacy of chemotherapy versus best supportive care, combination versus single agent chemotherapy and different combination chemotherapy regimens in advanced gastric cancer. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE up to March 2009, reference lists of studies, and contacted pharmaceutical companies and national and international experts. SELECTION CRITERIA: Randomised controlled trials on systemic intravenous chemotherapy versus best supportive care, combination versus single agent chemotherapy and different combination chemotherapies in advanced gastric cancer. DATA COLLECTION AND ANALYSIS: Two authors independently extracted data. A third investigator was consulted in case of disagreements. We contacted study authors to obtain missing information. MAIN RESULTS: Thirty five trials, with a total of 5726 patients, have been included in the meta-analysis of overall survival. The comparison of chemotherapy versus best supportive care consistently demonstrated a significant benefit in overall survival in favour of the group receiving chemotherapy (hazard ratios (HR) 0.37; 95% confidence intervals (CI) 0.24 to 0.55, 184 participants). The comparison of combination versus single-agent chemotherapy provides evidence for a survival benefit in favour of combination chemotherapy (HR 0.82; 95% CI 0.74 to 0.90, 1914 participants). The price of this benefit is increased toxicity as a result of combination chemotherapy. When comparing 5-FU/cisplatin-containing combination therapy regimens with versus without anthracyclines (HR 0.77; 95% CI 0.62 to 0.95, 501 participants) and 5-FU/anthracycline-containing combinations with versus without cisplatin (HR 0.82; 95% CI 0.73 to 0.92, 1147 participants) there was a significant survival benefit for regimens including 5-FU, anthracyclines and cisplatin. Both the comparison of irinotecan versus non-irinotecan (HR 0.86; 95% CI 0.73 to 1.02, 639 participants) and docetaxel versus non-docetaxel containing regimens (HR 0.93; 95% CI 0.75 to 1.15, 805 participants) show non-significant overall survival benefits in favour of the irinotecan and docetaxel-containing regimens. AUTHORS' CONCLUSIONS: Chemotherapy significantly improves survival in comparison to best supportive care. In addition, combination chemotherapy improves survival compared to single-agent 5-FU. All patients should be tested for their HER-2 status and trastuzumab should be added to a standard fluoropyrimidine/cisplatin regimen in patients with HER-2 positive tumours. Two and three-drug regimens including 5-FU, cisplatin, with or without an anthracycline, as well as irinotecan or docetaxel-containing regimens are reasonable treatment options for HER-2 negative patients.

Nosocomial nontyphoidal salmonellosis after antineoplastic chemotherapy : reactivation of asymptomatic colonization ?

Abstract An increased frequency of nontyphoidal salmonellosis is well established in cancer patients, but it is unclear whether this represents increased susceptibility to exogenous infection or opportunistic, endogenous reactivation of asymptomatic carriage. In a retrospective study, a simple case definition was used to identify the probable presence of reactivation salmonellosis in five cancer patients between 1996 and 2002. Reactivation salmonellosis was defined as the development of nosocomial diarrhea >72 h after admission and following the administration of antineoplastic chemotherapy in an HIV-seronegative cancer patient who was asymptomatic on admission, in the absence of epidemiological evidence of a nosocomial outbreak. Primary salmonellosis associated with unrecognized nosocomial transmission or community acquisition and an unusually prolonged incubation period could not entirely be ruled out. During the same time period, another opportunistic infection, Pneumocystis pneumonia, was diagnosed in six cancer patients. Presumably, asymptomatic intestinal Salmonella colonization was converted to invasive infection by chemotherapy-associated intestinal mucosal damage and altered innate immune mechanisms. According to published guidelines, stool specimens from patients hospitalized for longer than 72 h should be rejected unless the patient is neutropenic or ≥65 years old with significant comorbidity. However, in this study neutropenia was present in only one patient, and four patients were <65 years old. Guidelines should thus be revised in order not to reject stool culture specimens from such patients. In cancer patients, nosocomial salmonellosis can Occur as a chemo-therapy-triggered opportunistic reactivation infection that may be similar in frequency to Pneumocystis pneumonia.

Role of Kras Status in Patients with Metastatic Colorectal Cancer Receiving First-Line Chemotherapy plus Bevacizumab: A TTD Group Cooperative Study

BACKGROUND In the MACRO study, patients with metastatic colorectal cancer (mCRC) were randomised to first-line treatment with 6 cycles of capecitabine and oxaliplatin (XELOX) plus bevacizumab followed by either single-agent bevacizumab or XELOX plus bevacizumab until disease progression. An additional retrospective analysis was performed to define the prognostic value of tumour KRAS status on progression-free survival (PFS), overall survival (OS) and response rates. METHODOLOGY/PRINCIPAL FINDINGS KRAS data (tumour KRAS status and type of mutation) were collected by questionnaire from participating centres that performed KRAS analyses. These data were then cross-referenced with efficacy data for relevant patients in the MACRO study database. KRAS status was analysed in 394 of the 480 patients (82.1%) in the MACRO study. Wild-type (WT) KRAS tumours were found in 219 patients (56%) and mutant (MT) KRAS in 175 patients (44%). Median PFS was 10.9 months for patients with WT KRAS and 9.4 months for patients with MT KRAS tumours (p=0.0038; HR: 1.40; 95% CI:1.12-1.77). The difference in OS was also significant: 26.7 months versus 18.0 months for WT versus MT KRAS, respectively (p=0.0002; HR: 1.55; 95% CI: 1.23-1.96). Univariate and multivariate analyses showed that KRAS was an independent variable for both PFS and OS. Responses were observed in 126 patients (57.5%) with WT KRAS tumours and 76 patients (43.4%) with MT KRAS tumours (p=0.0054; OR: 1.77; 95% CI: 1.18-2.64). CONCLUSIONS/SIGNIFICANCE This analysis of the MACRO study suggests a prognostic role for tumour KRAS status in patients with mCRC treated with XELOX plus bevacizumab. For both PFS and OS, KRAS status was an independent factor in univariate and multivariate analyses.

Cancer cell-autonomous contribution of type I interferon signaling to the efficacy of chemotherapy.

Some of the anti-neoplastic effects of anthracyclines in mice originate from the induction of innate and T cell-mediated anticancer immune responses. Here we demonstrate that anthracyclines stimulate the rapid production of type I interferons (IFNs) by malignant cells after activation of the endosomal pattern recognition receptor Toll-like receptor 3 (TLR3). By binding to IFN-α and IFN-β receptors (IFNARs) on neoplastic cells, type I IFNs trigger autocrine and paracrine circuitries that result in the release of chemokine (C-X-C motif) ligand 10 (CXCL10). Tumors lacking Tlr3 or Ifnar failed to respond to chemotherapy unless type I IFN or Cxcl10, respectively, was artificially supplied. Moreover, a type I IFN-related signature predicted clinical responses to anthracycline-based chemotherapy in several independent cohorts of patients with breast carcinoma characterized by poor prognosis. Our data suggest that anthracycline-mediated immune responses mimic those induced by viral pathogens. We surmise that such 'viral mimicry' constitutes a hallmark of successful chemotherapy.

Modulation of Trypanosoma cruzi-specific T-cell responses after chemotherapy for chronic Chagas disease

The aim of this review is to describe the contributions of the knowledge of T-cell responses to the understanding of the physiopathology and the responsiveness to etiological treatment during the chronic phase of Chagas disease.T-helper (Th)1 and interleukin (IL)-10Trypanosoma cruzi-specific T-cells have been linked to the asymptomatic phase or to severe clinical forms of the disease, respectively orvice versa, depending on the T. cruziantigen source, the patient’s location and the performed immunological assays. Parasite-specific T-cell responses are modulated after benznidazole (BZ) treatment in chronically T. cruzi-infected subjects in association with a significant decrease in T. cruzi-specific antibodies. Accumulating evidence has indicated that treatment efficacy during experimental infection with T. cruziresults from the combined action of BZ and the activation of appropriate immune responses in the host. However, strong support of this interaction in T. cruzi-infected humans remains lacking. Overall, the quality of T-cell responses might be a key factor in not only disease evolution, but also chemotherapy responsiveness. Immunological parameters are potential indicators of treatment response regardless of achievement of cure. Providing tools to monitor and provide early predictions of treatment success will allow the development of new therapeutic options.