ELISA F29 -A therapeutic efficacy biomarker in Chagas disease: Evaluation in pediatric patients treated with nifurtimox and followed for 4 years post-treatment

BACKGROUND

Measurement of the success of antitrypanosomal treatment for Chagas disease is difficult, particularly in the chronic phase of the disease, because anti-Trypanosoma cruzi antibodies persist in serum for prolonged periods. We studied the effects of nifurtimox administered by two different treatment regimens on the T. cruzi calcium-binding flagellar protein F29 in children diagnosed with Chagas disease measured using an enzyme-linked immunosorbent assay (ELISA) technique (ELISA F29).

METHODS AND PRINCIPAL FINDINGS

In a phase 3, randomized, double-blind, parallel-group, historically controlled study (ClinicalTrials.gov NCT02625974), blood samples obtained from children diagnosed with Chagas disease and treated with nifurtimox for either 60 days or 30 days were analyzed using an ELISA with an F29 recombinant protein as the antigen, as well as conventional serological tests (recombinant ELISA and indirect hemagglutination assay). In an exploratory approach, serological response to nifurtimox treatment was evaluated for 4 years post-treatment. In both treatment groups, the number of patients with negative ELISA F29 values increased over the period of observation. The incidence rate of negative seroconversion using ELISA F29 was 22.94% (95% CI: 19.65%, 26.63%) in the 60-day treatment group and 21.64% (95% CI: 17.21%, 26.86%) in the 30-day treatment group. In the subpopulation of patients who tested seropositive for F29 before nifurtimox treatment, 88 patients (67.7%) in the 60-day regimen and 39 patients (59.1%) in the 30-day regimen were F29 seronegative at 4 years post-treatment. All patients who had a positive ELISA F29 test at baseline and seroconverted to negative measured by conventional serology reached seronegativity in ELISA F29 earlier than in conventional serology.

CONCLUSIONS

The results demonstrate a serological response to treatment with nifurtimox measured by the ELISA F29 test in children diagnosed with Chagas disease. The F29-based ELISA can be considered a potential early marker of response to antitrypanosomal therapy for Chagas disease.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02625974.

Efficacy and Safety of Nifurtimox in Pediatric Patients with Chagas Disease: Results at 4-Year Follow-Up in a Prospective, Historically Controlled Study (CHICO SECURE)

Nifurtimox is recommended for the treatment of Chagas disease; however, long-term follow-up data are scarce. This prolonged follow-up phase of the prospective, historically controlled, CHICO clinical trial evaluated seronegative conversion in pediatric patients aged <18 years with Chagas disease who were followed for 4 years after nifurtimox treatment. Patients were randomly assigned 2:1 to nifurtimox 60-day or 30-day regimens comprising 10 to 20 mg/kg/day for patients aged <12 years and body weight <40 kg, and 8 to 10 mg/kg/day for those aged ≥12 years and body weight ≥40 kg. Anti-Trypanosoma cruzi antibodies decreased during the study period, achieving seronegative conversion in 16 (8.12%) and 8 (8.16%) patients in the 60-day and 30-day nifurtimox regimens, respectively, with corresponding incidence rates per 100 patients/year of seronegative conversion of 2.12 (95% confidence interval [CI]: 1.21 to 3.45) and 2.11 (95% CI: 0.91 to 4.16). Superiority of the 60-day nifurtimox regimen was confirmed by the lower limit of the 95% CI being higher than that (0%) in a historical placebo control group. Children aged <2 years at baseline were more likely to reach seronegative conversion during the 4-year follow-up than older children. At any annual follow-up visit, >90% of evaluable patients had persistently negative quantitative PCR results for T. cruzi DNA. No adverse events potentially related to treatment or caused by protocol-required procedures were documented for either treatment regimen. This study confirms the effectiveness and safety of a pediatric formulation of nifurtimox administered in an age- and weight-adjusted regimen for 60 days to treat children with Chagas disease.

Nifurtimox for Treatment of Chagas Disease in Pediatric Patients: the Challenges of Applying Pharmacokinetic-Pharmacodynamic Principles to Dose Finding

The antiparasitic drug nifurtimox was approved in the USA in 2020 for the treatment of patients with Chagas disease aged less than 18 years and weighing at least 2.5 kg, based on outcomes from the phase 3 CHICO study. Accordingly, pediatric patients with Chagas disease take nifurtimox thrice daily with food at one of two body weight–adjusted dose ranges. We investigated possible relationships between pharmacokinetic (PK) data, and pharmacodynamic efficacy and safety data collected in an analysis population of 111 participants in CHICO, using a published population PK model to estimate nifurtimox exposure at the patient level. Pediatric exposure to nifurtimox was benchmarked against levels of nifurtimox exposure known to be effective in adults with Chagas disease. Given the complex dosing regimen for nifurtimox, we also modeled nifurtimox exposure associated with simpler dosing strategies. We found no relationship between exposure to nifurtimox and efficacy measures (e.g., serological response to treatment), or between exposure and safety outcomes (including typical adverse events, e.g., headache, decreased appetite, nausea/vomiting). The analysis population appeared to represent the overall CHICO population based on the similarity of their baseline characteristics and the profiles of adverse events in the two groups. Modeled exposure based on the dosing regimen in CHICO was within the reference range derived from phase 1 data in adults. The relationship between nifurtimox exposure and cure is complex; a simplified pediatric dosing regimen is unlikely to be beneficial.

Graphical abstract

Serological response to nifurtimox in adult patients with chronic Chagas disease: An observational comparative study in Argentina

Nifurtimox is indicated in Chagas disease but determining its effectiveness in chronic disease is hindered by the length of time needed to demonstrate negative serological conversion. We manually reviewed long-term follow-up data from hospital records of patients with chronic Chagas disease (N = 1,497) in Argentina diagnosed during 1967-1980. All patients were aged ≥18 years at diagnosis and were either treated with nifurtimox (n = 968) or received no antitrypanosomal treatment (n = 529). The primary endpoint was negative seroconversion (the "event"), defined as a change from positive to negative in the serological or parasitological laboratory test used at diagnosis. Time to event was from baseline visit to date of endpoint event or censoring. The effectiveness of nifurtimox versus no treatment was estimated with Cox proportional hazard regression using propensity scores with overlap weights to calculate the hazard ratio and 95% confidence interval. The nifurtimox group was younger than the untreated group (mean, 32.4 vs. 40.3 years), with proportionally fewer females (47.9% vs. 60.1%), and proportionally more of the nifurtimox group than the untreated group had clinical signs and symptoms of Chagas disease at diagnosis (28.9% vs. 14.0%). Median maximum daily dose of nifurtimox was 8.0 mg/kg/day (interquartile range [IQR]: 8.0-9.0) and median treatment duration was 44 days (IQR: 1-90). Median time to event was 2.1 years (IQR: 1.0-4.5) for nifurtimox-treated and 2.4 years (IQR: 1.0-4.2) for untreated patients. Accounting for potential confounders, the estimated hazard ratio (95% confidence interval) for negative seroconversion was 2.22 (1.61-3.07) favoring nifurtimox. Variable treatment regimens and follow-up duration, and an uncommonly high rate of spontaneous negative seroconversion, complicate interpretation of this epidemiological study, but with the longest follow-up and largest cohort analyzed to date it lends weight to the benefit of nifurtimox in adults with chronic Chagas disease. Trial registration: The study protocol was registered at ClinicalTrials.gov: NCT03784391.

Prospective, historically controlled study to evaluate the efficacy and safety of a new paediatric formulation of nifurtimox in children aged 0 to 17 years with Chagas disease one year after treatment (CHICO)

Nifurtimox is a recommended treatment for Chagas disease, but data from treated children are limited. We investigated the efficacy, safety and tolerability of nifurtimox administered as divisible, dispersible 30 mg and 120 mg tablets in children with Chagas disease. In this blinded, controlled study conducted January 2016-July 2018, 330 patients aged <18 years from 25 medical centres across three South American countries were randomised 2:1 to nifurtimox 10-20 mg/kg/day (aged <12 years) or 8-10 mg/kg/day (aged ≥12 years) for 60 days (n = 219), or for 30 days plus placebo for 30 days (n = 111) (ClinicalTrials.gov NCT02625974). The primary outcome was anti-Trypanosoma cruzi serological response (negative seroconversion or seroreduction ≥20% in mean optical density from baseline determined by two conventional enzyme-linked immunosorbent assays) at 12 months in the 60-day treatment group versus historical placebo controls. Nifurtimox for 60 days achieved negative seroconversion (n = 10) and seroreduction (n = 62) in 72 patients (serological response 32.9%; 95% confidence interval [CI] 26.4%, 39.3%, of all treated patients), confirming superiority relative to the upper 95% CI of 16% for controls. In patients aged <8 months, 10/12 treated for 60 days (83.3%) and 5/7 treated for 30 days (71.4%) achieved negative seroconversion. Overall serological response was lower for 30-day than for 60-day nifurtimox (between-treatment difference 14.0% [95% CI 3.7%, 24.2%]). The frequency of T. cruzi-positive quantitative polymerase chain reactions decreased substantially from baseline levels (60-day regimen 53.4% versus 1.4%; 30-day regimen 51.4% versus 4.5%). Study drug-related treatment-emergent adverse events (TEAEs), which were observed in 62 patients (28.3%) treated for 60 days and 29 patients (26.1%) treated for 30 days, were generally mild or moderate and resolved without sequelae; 4.2% of all TEAEs led to nifurtimox discontinuation. Age- and weight-adjusted nifurtimox for 60 days achieved a serological response at 12 months post-treatment that was superior to historical placebo, was well tolerated and had a favourable safety profile in children with Chagas disease. Although, at 1 year serological follow-up, efficacy of the shorter nifurtimox treatment was not comparable to the 60-day treatment regimen for the overall study population, further long-term follow-up of the patients will provide important information about the progress of serological conversion in children treated with nifurtimox, as well as the potential efficacy difference between the two regimens over time.

Comparison of Occlusive and Open Application in a Psoriasis Plaque Test Design, Exemplarily Using Investigations of Mapracorat 0.1% Ointment versus Vehicle and Reference Drugs

BACKGROUND/AIMS

Psoriasis plaque tests (PPTs) are important tools in the early phases of antipsoriatic drug development. Two distinct PPT design variants (open vs. occluded drug application) are commonly used, but no previous work has aimed to directly compare and contrast their performance.

METHODS

We compared the antipsoriatic efficacy of mapracorat 0.1% ointment and reference drugs reported in 2 separate studies, representing open and occluded PPT designs. The drug effect size was measured by sonography (mean change in echo-poor band thickness), chromametry, and standardized clinical assessment.

RESULTS

Antipsoriatic effects were detectable for the study drugs in both occluded and open PPTs. Differences between the potency of antipsoriatic drugs and vehicle were observable. The total antipsoriatic effect size appeared to be higher in the occluded PPT than the open PPT, despite the shorter treatment duration (2 vs. 4 weeks). Effect dynamics over time revealed greater differences between some study drugs in the open PPT compared to the occluded PPT.

CONCLUSION

Taking the higher technical challenges for the open PPT into account, we recommend the occluded PPT as a standard screening setting in early drug development. In special cases, considering certain drug aspects or study objectives that would require procedural adaptations, an open PPT could be the better-suited design. Finally, both PPT models show clear advantages: classification as phase I studies, small number of psoriatic subjects, relatively short study duration, excellent discrimination between compounds and concentrations, parallel measurement of treatment response, and go/no go decisions very early in clinical development.

Application of ubiquitous computing in personal health monitoring systems

A possibility to significantly reduce the costs of public health systems is to increasingly use information technology. The Laboratory for Information Processing Technology (ITIV) at the University of Karlsruhe is developing a personal health monitoring system, which should improve health care and at the same time reduce costs by combining micro-technological smart sensors with personalized, mobile computing systems. In this paper we present how ubiquitous computing theory can be applied in the health-care domain.

The nuclear membrane-associated honeycomb structure of the unicellular organism Amoeba proteus: on the search for homologies with the nuclear lamina of metazoa

In the protozoon Amoeba proteus, a complex and highly organized structure with the morphology of a honeycomb is associated with the nucleoplasmic surface of the nuclear membrane. We have tested whether this structure exhibits similarity to the nuclear lamina of metazoic organisms. First, we have shown that the honeycomb layer is composed of 3 to 5 nm thick protein fibrils resistant to treatment with detergent, high salt, and digestion with nucleases, thus possessing properties typical for karyoskeletal elements. However, in contrast to the meshwork of lamin filaments in somatic cells of metazoic organisms, the honeycomb layer is not tightly anchored to the nucleoplasmic side of pore complexes, or to the inner nuclear membrane. Second, in microinjection experiments we investigated whether fluorescently labeled lamins of Xenopus laevis (lamins A and LI) and Drosophila melanogaster (lamin Dmo) were able to associate in vivo with the Amoeba proteus honeycomb structure. In microinjected amoeba these three lamins were efficiently transported into the nucleus, but did not associate with the nuclear envelope. Our results suggest that the Amoeba proteus nuclear envelope, including the honeycomb layer, does not contain proteins exhibiting high homologies to lamins of metazoan species thus preventing the localized assembly of microinjected lamins along the nuclear periphery.