Safety and efficacy of single dose versus multiple doses of AmBisome for treatment of visceral leishmaniasis in eastern Africa: a randomised trial

A phase II, non-comparative randomised trial of two treatments involving liposomal amphotericin B and miltefosine for post-kala-azar dermal leishmaniasis in India and Bangladesh

BACKGROUND

In Southeast Asia, treatment is recommended for all patients with post-kala-azar dermal leishmaniasis (PKDL). Adherence to the first-line regimen, twelve weeks of miltefosine (MF), is low and ocular toxicity has been observed with this exposure period. We assessed the safety and efficacy of two shorter-course treatments: liposomal amphotericin B (LAmB) alone and combined with MF.

METHODOLOGY/PRINCIPAL FINDINGS

An open-label, phase II, randomized, parallel-arm, non-comparative trial was conducted in patients with parasitologically confirmed PKDL, 6 to ≤60 years. Patients were assigned to 20 mg/kg LAmB (total dose, in five injections over 15 days) alone or combined with allometric MF (3 weeks). The primary endpoint was definitive cure at 12 months, defined as complete resolution of papular and nodular lesions and >80% re-pigmentation of macular lesions. Definitive cure at 24 months was a secondary efficacy endpoint. 118/126 patients completed the trial. Definitive cure at 12 months was observed in 29% (18/63) patients receiving LAmB and 30% (19/63) receiving LAmB/MF (mITT), increasing to 58% and 66%, respectively, at 24 months. Most lesions had resolved/improved at 12 and 24 months for patients receiving LAmB (90%, 83%) and LAmB/MF (85%, 88%) by qualitative assessment. One death, unrelated to study drugs, was reported; no study drug-related serious adverse events were observed. The most frequent adverse drug reactions were MF-related vomiting and nausea, and LAmB-related hypokalaemia and infusion reactions. Most adverse events were mild; no ocular adverse events occurred.

CONCLUSIONS/SIGNIFICANCE

Both regimens are suitably safe and efficacious alternatives to long-course MF for PKDL in South Asia.

TRIAL REGISTRATION

CTRI/2017/04/008421.

Activation of neutrophils excels the therapeutic potential of Mycobacterium indicus pranii and heat-induced promastigotes against antimony-resistant Leishmania donovani infection

Repurposing drugs and adjuvants is an attractive choice of present therapy that reduces the substantial costs, chances of failure, and systemic toxicity. Mycobacterium indicus pranii was originally developed as a leprosy vaccine but later has been found effective against Leishmania donovani infection. To extend our earlier study, here we reported the immunotherapeutic modulation of the splenic and circulatory neutrophils in favour of hosts as neutrophils actually serve as the pro-parasitic portable shelter to extend the Leishmania infection specifically during the early entry into the hosts' circulation. We targeted to disrupt this early pro-parasitic incidence by the therapeutic combination of M. indicus pranii and heat-induced promastigotes against antimony-resistant L. donovani infection. The combination therapy induced the functional expansion of CD11b+Ly6CintLy6Ghi neutrophils both in the post-infected spleen, and also in the circulation of post-treated animals followed by the immediate Leishmania infection. More importantly, the enhanced expression of MHC-II, phagocytic uptake of the parasites by the circulatory neutrophils as well as the oxidative burst were induced that limited the chances of the very early establishment of the infection. The enhanced expression of pro-inflammatory cytokines, like IL-1α and TNF-α indicated resistance to the parasite-mediated takeover of the neutrophils, as these cytokines are critical for the activation of T cell-mediated immunity and host-protective responses. Additionally, the induction of essential transcription factors and cytokines for early granulocytic lineage commitment suggests that the strategy not only contributed to the peripheral activation of the neutrophils but also promoted granulopoiesis in the bone marrow.

The status of combination therapy for visceral leishmaniasis: an updated review

For the past 15 years, trials of combination therapy options for visceral leishmaniasis have been conducted with the aim of identifying effective, and safe treatment regimens that were shorter than existing monotherapy regimens and could also prevent or delay the emergence of drug resistance. Although first-line treatment currently relies on combination therapy in east Africa, this is not true in Latin America owing to disappointing trial results, with lower than expected efficacy seen for the combination treatment group. By contrast, several effective combination therapy regimens have been identified through trials on the Indian subcontinent; yet, first-line therapy is still AmBisome monotherapy as the drug is part of a free donation programme and is highly effective in this region. Achieving a short all-oral combination treatment will require new chemical entities, several of which are currently under evaluation. Future studies should systematically include pharmacological substudies to ensure optimal dosing for all patient groups. To achieve maximal impact of new combination treatments, mechanisms to ensure drug availability and access after trials should be established. Enhancing the longevity of current and novel treatments will require effective systems for early detection of emerging drug resistance.

The increasing incidence of visceral leishmaniasis relapse in South Sudan: A retrospective analysis of field patient data from 2001-2018

BACKGROUND

Visceral Leishmaniasis (VL) is endemic in South Sudan, manifesting periodically in major outbreaks. Provision of treatment during endemic periods and as an emergency response is impeded by instability and conflict. Médecins Sans Frontières (MSF) has provided health care in South Sudan since the late 1980's, including treatment for 67,000 VL patients. In recent years, MSF monitoring data have indicated increasing numbers of VL relapse cases. A retrospective analysis of these data was performed in order to provide insight into the possible causes of this increase.

METHODOLOGY/PRINCIPAL FINDINGS

Programme monitoring data from the MSF hospital in Lankien, Jonglei State, South Sudan, for the period 2001-2018 were analysed to detect trends in VL relapse as a proportion of all VL cases presenting to MSF treatment centres. Routinely collected patient-level data from relapse and primary VL cases treated at all MSF sites in South Sudan over the same period were analysed to describe patient characteristics and treatments received. VL relapse as a proportion of all VL cases increased by 6.5% per annum (95% CI 0.3% to 13.0%, p = 0.04), from 5.2% during 2001-2003 to 14.4% during 2016-2018. Primary VL and VL relapse patients had similar age, sex and anthropometric characteristics, the latter indicating high indices of undernutrition which were relatively constant over time. Clinical factors (Hb, spleen size, and VL severity score) also did not vary substantially over time. SSG/PM was the main treatment regimen from 2001-2018, used in 68.7% of primary and 70.9% of relapse VL cases; AmBisome was introduced in 2013, received by 22.5% of primary VL and 32.6% of VL relapse cases from 2013-2018.

CONCLUSION

Increasing incidence of VL relapse in South Sudan does not appear to be explained by changes in patient characteristics or other factors. Our data are concerning and may indicate an emergence of treatment-resistant parasite strains, decreasing the effectiveness of treatment regimens. This warrants further investigation as a causal factor. New chemical entities that will enable safe and highly effective short-course oral treatments for VL are urgently needed.

Infectious diseases data observatory (IDDO) visceral leishmaniasis library of clinical therapeutic studies: A protocol for a living systematic review of clinical studies

Introduction: Visceral leishmaniasis (VL) is a vector-borne disease caused by protozoan parasites of the genus Leishmania. The disease is endemic in parts of South Asia, East Africa, South America and the Mediterranean region, with an estimated 50,000 to 90,000 cases occurring annually. A living systematic review of existing scientific literature is proposed to identify clinical drug efficacy studies against VL, conducted following the Preferred Reporting Items for Systematic-Reviews and Meta-Analyses (PRISMA) guidelines. Methods and analysis: The proposed living systematic review builds on a previous systematic review first carried out in 2016, and the current protocol is designed to capture any published or registered VL clinical study from Nov-2021 onwards. The following databases will be searched by a medical librarian: PubMed, Ovid Embase, Scopus, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, clinicaltrials.gov, WHO ICTRP, as well as IMEMR, IMSEAR, and LILACS from the WHO Global Index Medicus. The systematic review will consider both randomised and non-randomised interventional studies, including single-armed studies. Ethics and dissemination: A database of eligible studies, including study characteristics, is openly available (https://www.iddo.org/tool/vl-surveyor) and will be continually updated every six months. All findings will be published in a peer-reviewed journal. PROSPERO registration: CRD42021284622 (29/11/2021)

Tackling Drug Resistance and Other Causes of Treatment Failure in Leishmaniasis

Leishmaniasis is a tropical infectious disease caused by the protozoan Leishmania parasite. The disease is transmitted by female sand flies and, depending on the infecting parasite species, causes either cutaneous (stigmatizing skin lesions), mucocutaneous (destruction of mucous membranes of nose, mouth and throat) or visceral disease (a potentially fatal infection of liver, spleen and bone marrow). Although more than 1 million new cases occur annually, chemotherapeutic options are limited and their efficacy is jeopardized by increasing treatment failure rates and growing drug resistance. To delay the emergence of resistance to existing and new drugs, elucidating the currently unknown causes of variable drug efficacy (related to parasite susceptibility, host immunity and drug pharmacokinetics) and improved use of genotypic and phenotypic tools to define, measure and monitor resistance in the field are critical. This review highlights recent progress in our understanding of drug action and resistance in Leishmania, ongoing challenges (including setbacks related to the COVID-19 pandemic) and provides an overview of possible strategies to tackle this public health challenge.

Road-map of pre-clinical treatment for Visceral Leishmaniasis

Visceral leishmaniasis (VL) or Kala-azar, is the most lethal form of leishmaniasis, is still prevalent in many countries where it is endemic. It is a threat to human life caused by protozoan parasite Leishmania donovani. The severity of the disease is further increased as the treated individuals might have a chance of developing Post Kala-azar Dermal Leishmaniasis (PKDL) in the long run. Moreover, several countries have reported high number of HIV-VL co-infected patients. Therefore, there is a dire need for the development of efficient diagnostic methods and drugs in order to combat the disease and to control the spread of disease. At present, the treatment for VL entirely relies on therapeutic drugs as no vaccine is available yet. Ever since 1900s a series of drugs have been invented and used for treatment of VL; but the need for one such cost-effective treatment that would completely cure the disease with minimal side-effects, low relapse rate with high efficacy and less toxicity remains yet to be fulfilled. Therefore, identifying novel compounds is very crucial to develop potent antileishmanial agents. Thus, this review enlists several instances of drug development, including the pharmacokinetic and pharmacodynamic properties of antileishmanial drugs, different experimental animal models used to investigate the disease progression and to analyze treatment dosage and pharmacological aspect of drugs. Furthermore, the existing gap in drug development and future measures to improve the process are also discussed in this review.

Antiprotozoal agents: How have they changed over a decade?

Neglected tropical diseases are a diverse group of communicable diseases that are endemic in low- or low-to-middle-income countries located in tropical and subtropical zones. The number and availability of drugs for treating these diseases are low, the administration route is inconvenient in some cases, and most of them have safety, efficacy, or adverse/toxic reaction issues. The need for developing new drugs to deal with these issues is clear, but one of the most drastic consequences of this negligence is the lack of interest in the research and development of new therapeutic options among major pharmaceutical companies. Positive changes have been achieved over the last few years, although the overall situation remains alarming. After more than one decade since the original work reviewing antiprotozoal agents came to light, now it is time to question ourselves: How has the scenario for the treatment of protozoal diseases such as malaria, leishmaniasis, human African trypanosomiasis, and American trypanosomiasis changed? This review covers the last decade in terms of the drugs currently available for the treatment of these diseases as well as the clinical candidates being currently investigated.

Anfotericina B liposomal en el tratamiento de la leishmaniasis visceral

A review on the current evidence of the efficacy and security of liposomal amphotericinB (L-AmB) for the treatment of visceral leishmaniasis (VL) has been performed. In the Indian subcontinent, a single dose of 10mg/kg has shown effectiveness in the treatment of VL due to Leishmania donovani. In contrast, higher doses of L-AmB (up to 30mg/kg) are required in Africa to treat a VL of the same etiology. When treating VL by Leishmania infantum acquired in the Americas and Europe the usual dose of L-AmB is 20-21mg/kg. In HIV co-infected patients the required doses are usually higher, up to 60mg/kg, and if it is administered in a prophylactic schedule after the treatment of VL relapses are reduced. L-AmB has shown synergism with other antiparasitic drugs, especially with paromomycin in the Indian subcontinent and with miltefosin in patients coinfected with HIV in East Africa. Due to its efficacy and safety profile, L-AmB is the first therapeutic option for VL.

Pharmacokinetic / pharmacodynamic relationships of liposomal amphotericin B and miltefosine in experimental visceral leishmaniasis

BACKGROUND

There is a continued need to develop effective and safe treatments for visceral leishmaniasis (VL). Preclinical studies on pharmacokinetics and pharmacodynamics of anti-infective agents, such as anti-bacterials and anti-fungals, have provided valuable information in the development and dosing of these agents. The aim of this study was to characterise the pharmacokinetic and pharmacodynamic properties of the anti-leishmanial drugs AmBisome and miltefosine in a preclinical disease model of VL.

METHODOLOGY / PRINCIPAL FINDINGS

BALB/c mice were infected with L. donovani (MHOM/ET/67/HU3) amastigotes. Groups of mice were treated with miltefosine (orally, multi-dose regimen) or AmBisome (intravenously, single dose regimen) or left untreated as control groups. At set time points groups of mice were killed and plasma, livers and spleens harvested. For pharmacodynamics the hepatic parasite burden was determined microscopically from tissue impression smears. For pharmacokinetics drug concentrations were measured in plasma and whole tissue homogenates by LC-MS. Unbound drug concentrations were determined by rapid equilibrium dialysis. Doses exerting maximum anti-leishmanial effects were 40 mg/kg for AmBisome and 150 mg/kg (cumulatively) for miltefosine. AmBisome displayed a wider therapeutic range than miltefosine. Dose fractionation at a total dose of 2.5 mg/kg pointed towards concentration-dependent anti-leishmanial activity of AmBisome, favouring the administration of large doses infrequently. Protein binding was >99% for miltefosine and amphotericin B in plasma and tissue homogenates.

CONCLUSION / SIGNIFICANCE

Using a PK/PD approach we propose optimal dosing strategies for AmBisome. Additionally, we describe pharmacokinetic and pharmacodynamic properties of miltefosine and compare our findings in a preclinical disease model to available knowledge from studies in humans. This approach also presents a strategy for improved use of animal models in the drug development process for VL.

Structural characterization of naphthalene sulfonamides and a sulfonate ester and their in vitro efficacy against Leishmania tarentolae promastigotes

Structural and biological activity analyses of two naphthalene sulfonamides and a naphthalene sulfonate ester.

The advantages of nanomedicine in the treatment of visceral leishmaniasis: between sound arguments and wishful thinking

Introduction: Although life-threatening if left untreated, visceral leishmaniasis (VL) is still a neglected endemic disease in 98 countries worldwide. The number of drugs available is low and few are in clinical trials. In the last decades, efforts have been made on the development of nanocarriers as drug delivery systems to treat VL. Given the preferential intracellular location of the parasite in the liver and spleen macrophages, the rationale is sturdy. In a clinical setting, liposomal amphotericin B displays astonishing cure rates.Areas covered: A literature search was performed through PubMed and Google Scholar. We critically reviewed the main literature highlighting the success of nanomedicine in VL. We also reviewed the hurdles and yet unfulfilled promises rising awareness of potential drawbacks of nanomedicine in VL.Expert opinion: VL is a disease where nanomedicines successes shine through. However, there are a lot of obstacles on the road to developing more efficient strategies such as targeting functionalization, oral formulations, or combined therapies. And those strategies raise many questions.

The adaptive designs CONSORT extension (ACE) statement: a checklist with explanation and elaboration guideline for reporting randomised trials that use an adaptive design

Adaptive designs (ADs) allow pre-planned changes to an ongoing trial without compromising the validity of conclusions and it is essential to distinguish pre-planned from unplanned changes that may also occur. The reporting of ADs in randomised trials is inconsistent and needs improving. Incompletely reported AD randomised trials are difficult to reproduce and are hard to interpret and synthesise. This consequently hampers their ability to inform practice as well as future research and contributes to research waste. Better transparency and adequate reporting will enable the potential benefits of ADs to be realised.This extension to the Consolidated Standards Of Reporting Trials (CONSORT) 2010 statement was developed to enhance the reporting of randomised AD clinical trials. We developed an Adaptive designs CONSORT Extension (ACE) guideline through a two-stage Delphi process with input from multidisciplinary key stakeholders in clinical trials research in the public and private sectors from 21 countries, followed by a consensus meeting. Members of the CONSORT Group were involved during the development process.The paper presents the ACE checklists for AD randomised trial reports and abstracts, as well as an explanation with examples to aid the application of the guideline. The ACE checklist comprises seven new items, nine modified items, six unchanged items for which additional explanatory text clarifies further considerations for ADs, and 20 unchanged items not requiring further explanatory text. The ACE abstract checklist has one new item, one modified item, one unchanged item with additional explanatory text for ADs, and 15 unchanged items not requiring further explanatory text.The intention is to enhance transparency and improve reporting of AD randomised trials to improve the interpretability of their results and reproducibility of their methods, results and inference. We also hope indirectly to facilitate the much-needed knowledge transfer of innovative trial designs to maximise their potential benefits. In order to encourage its wide dissemination this article is freely accessible on the BMJ and Trials journal websites."To maximise the benefit to society, you need to not just do research but do it well" Douglas G Altman.

The Adaptive designs CONSORT Extension (ACE) statement: a checklist with explanation and elaboration guideline for reporting randomised trials that use an adaptive design

Adaptive designs (ADs) allow pre-planned changes to an ongoing trial without compromising the validity of conclusions and it is essential to distinguish pre-planned from unplanned changes that may also occur. The reporting of ADs in randomised trials is inconsistent and needs improving. Incompletely reported AD randomised trials are difficult to reproduce and are hard to interpret and synthesise. This consequently hampers their ability to inform practice as well as future research and contributes to research waste. Better transparency and adequate reporting will enable the potential benefits of ADs to be realised.This extension to the Consolidated Standards Of Reporting Trials (CONSORT) 2010 statement was developed to enhance the reporting of randomised AD clinical trials. We developed an Adaptive designs CONSORT Extension (ACE) guideline through a two-stage Delphi process with input from multidisciplinary key stakeholders in clinical trials research in the public and private sectors from 21 countries, followed by a consensus meeting. Members of the CONSORT Group were involved during the development process.The paper presents the ACE checklists for AD randomised trial reports and abstracts, as well as an explanation with examples to aid the application of the guideline. The ACE checklist comprises seven new items, nine modified items, six unchanged items for which additional explanatory text clarifies further considerations for ADs, and 20 unchanged items not requiring further explanatory text. The ACE abstract checklist has one new item, one modified item, one unchanged item with additional explanatory text for ADs, and 15 unchanged items not requiring further explanatory text.The intention is to enhance transparency and improve reporting of AD randomised trials to improve the interpretability of their results and reproducibility of their methods, results and inference. We also hope indirectly to facilitate the much-needed knowledge transfer of innovative trial designs to maximise their potential benefits.

A Comprehensive Review of Cutaneous Leishmaniasis in Sri Lanka and Identification of Existing Knowledge Gaps

Purpose

Sri Lanka is endemic to cutaneous leishmaniasis and reported as the latest focus of leishmaniasis in the Asian subcontinent. Annually, the number of leishmaniasis cases is increasing; therefore, more efficient diagnostic tools, treatment methods and effective prevention measures are indispensable. For this reason, many studies were conducted regarding leishmaniasis infections in Sri Lanka; however, some areas need more attention. Thus, in this review, we comprehensively discussed the studies on leishmaniasis carried out in Sri Lanka.

Methods

Published articles on leishmaniasis in Sri Lanka were searched on PubMed, Google Scholar and ResearchGate databases. Inclusion criteria for the articles were based on keyword searches including ‘Leishmaniasis in Sri Lanka’, ‘Leishmaniasis vector in Sri Lanka’, ‘Sandfly species in Sri Lanka’, ‘Leishmaniasis epidemiology in Sri Lanka’ which are publicly accessible as of 15th July 2019.

Results

In this study, we evaluated and summarized the leishmaniasis reports in Sri Lanka and mainly focused on clinical presentation of leishmaniasis infection, genetic characteristics of Leishmania donovani Sri Lankan strain, geographical distribution and associated environmental factors, immunological aspects of the infection, vector, reservoir host, risk factors, diagnosis and treatment, and prevention and control. Furthermore, we identified the areas where further research is needed to fill the essential knowledge gaps.

Conclusions

Leishmaniasis has become a critically important parasitic infection in Sri Lanka, whereas the significant clinical form is cutaneous leishmaniasis. Prevalence of the leishmaniasis infections is reported from all the districts of the country. Therefore, more studies are essential to be carried out to fill the existing knowledge gaps emphasized in this review.

Impact of sequelae of visceral leishmaniasis and their contribution to ongoing transmission of Leishmania donovani

Visceral leishmaniasis (VL) in the Old World is caused by infection with Leishmania donovani. Although the numbers of new reported cases of VL in Africa have been relatively stable for several years, the low numbers currently reported on the Indian subcontinent suggest a positive impact of new treatments and intervention strategies. In both regions, however, VL relapse and post-kala-azar dermal leishmaniasis (PKDL) maintain infectious reservoirs and therefore present a threat to control programs. In this review, we outline the evolving appreciation of PKDL as an impactful disease in its own right and discuss the various diagnostic methods that can be applied for the detection and characterization of PKDL cases. We also highlight the data that indicate the potential, and likely contribution, of PKDL cases to ongoing transmission of L. donovani.

Visceral Leishmaniasis: Recent Advances in Diagnostics and Treatment Regimens

Diagnostic advances in visceral leishmaniasis include the development of the rK39 and rK28 rapid diagnostic test. The direct agglutination test is also increasingly used, as well as conventional and real-time polymerase chain reaction, which also performs well on peripheral blood. The choice of treatment for visceral leishmaniasis depends on the geographic region where the infection is acquired. Liposomal amphotericin B is generally found to be safe and effective in most endemic regions of the world; antimonials still remain to be the most effective in eastern Africa despite its high toxicity. Combination therapy is increasingly explored. Immunosuppressed patients require adapted diagnostic and therapeutic strategies.

Exploring global and country-level barriers to an effective supply of leishmaniasis medicines and diagnostics in eastern Africa: a qualitative study

OBJECTIVES

To understand stakeholders' perceptions of the access barriers to quality-assured diagnostics and medicines for leishmaniasis in the high-burden region of eastern Africa, and to identify key bottlenecks to improve the supply of commodities for neglected tropical diseases.

DESIGN

Desk reviews and qualitative in-depth interview study with purposive sampling.

METHODS

A landscape analysis through literature and desk review was performed. Next, 29 representatives from international organisations, non-governmental agencies, national control programmes from six countries (Ethiopia, Kenya, Somalia, South Sudan, Sudan and Uganda) and manufacturers were interviewed between May and July 2018. Participants were selected purposively and expanded through a snowballing technique.Data analysis was aided by NVivo, applying the framework method as a part of the thematic content analysis approach.

RESULTS

The barriers along the visceral leishmaniasis (VL) supply chain were identified as emerging themes, grouped across supply chain activities and health systems component(s). Stakeholders expressed the perception of progress, but bottlenecks persist. VL medicines, in general, lack multisource production capacity and with small market volume, expansion of suppliers is difficult. Procurement is plagued by forecasting difficulties, complex regulatory policies and procedures, and distribution challenges. Weak communication and coordination across different levels resulted in shortages and loss of trust among different actors. Cross-cutting issues spanned from limited political and resource commitment due to low awareness and limited in-country capacity. However, study respondents were optimistic to pursue several remedies, most importantly to build bridges between supply and demand sides through continued dialogue and collaborations. Diagnostics supply has mostly been overlooked; thus, improved investment in this area is needed.

CONCLUSIONS

Addressing supply barriers in eastern Africa requires consistent, specific efforts at the global and national levels, progressing from current partnerships and agreements. Priority actions include pooled procurement, improved forecast, and increased commitment and resources. Sustainability remains an elusive goal, yet to be integrated into discussions moving forward.

Preclinical candidate for the treatment of visceral leishmaniasis that acts through proteasome inhibition

Visceral leishmaniasis (VL), caused by the protozoan parasites Leishmania donovani and Leishmania infantum, is one of the major parasitic diseases worldwide. There is an urgent need for new drugs to treat VL, because current therapies are unfit for purpose in a resource-poor setting. Here, we describe the development of a preclinical drug candidate, GSK3494245/DDD01305143/compound 8, with potential to treat this neglected tropical disease. The compound series was discovered by repurposing hits from a screen against the related parasite Trypanosoma cruzi Subsequent optimization of the chemical series resulted in the development of a potent cidal compound with activity against a range of clinically relevant L. donovani and L. infantum isolates. Compound 8 demonstrates promising pharmacokinetic properties and impressive in vivo efficacy in our mouse model of infection comparable with those of the current oral antileishmanial miltefosine. Detailed mode of action studies confirm that this compound acts principally by inhibition of the chymotrypsin-like activity catalyzed by the β5 subunit of the L. donovani proteasome. High-resolution cryo-EM structures of apo and compound 8-bound Leishmania tarentolae 20S proteasome reveal a previously undiscovered inhibitor site that lies between the β4 and β5 proteasome subunits. This induced pocket exploits β4 residues that are divergent between humans and kinetoplastid parasites and is consistent with all of our experimental and mutagenesis data. As a result of these comprehensive studies and due to a favorable developability and safety profile, compound 8 is being advanced toward human clinical trials.

Walking a tightrope: drug discovery in visceral leishmaniasis

The current commitment of the pharma industry, nongovernmental organizations and academia to find better treatments against neglected tropical diseases should end decades of challenge caused by these global scourges. The initial result of these efforts has been the introduction of enhanced combinations of drugs, currently in clinical use, or formulations thereof. Phenotypic screening based on intracellular parasite infections has been revealed as the first key tool of antileishmanial drug discovery, because most first-in-class drugs entering Phase I trials were discovered this way. The professional commitment among stakeholders has enabled the availability of a plethora of new chemical entities that fit the target product profile for these diseases. However, the rate of hit discovery in leishmaniasis is far behind that for other neglected diseases. This review defends the need to develop new screening methods that consider the part played not only by intracellular parasites but also by the host's immune system to generate disease-relevant assays and improve clinical outcomes.

Treatment outcomes of visceral leishmaniasis in Ethiopia from 2001 to 2017: a systematic review and meta-analysis

Background

Ethiopia has the highest number of visceral leishmaniasis (VL) cases after Sudan in Sub-Saharan Africa. However, there was lack of comprehensive data on VL treatment outcome despite the huge burden of the diseases in the country. Hence, we aimed to perform a systematic review and meta-analysis on this topic to obtain stronger evidence on treatment outcomes of VL from the existing literature in Ethiopia.

Methods

The Cochrane guidelines to conduct meta-analysis following the Preferred Reporting Items for Systematic review and Meta-Analysis statement was used to conduct a computerized systematic search of the PubMed, Google Scholar, and ScienceDirect databases. Random effects model was used to combine studies showing heterogeneity of Cochrane Q P < 0.10 and I² > 50. Treatment outcomes were assessed at end of treatment and at 6 months follow-up. Subgroup analyses were performed on treatment outcomes based on the different antileishmanial treatment options and patients’ HIV status.

Results

Fifteen studies were included in the final analyses. At end of treatment, an overall treatment success rate of 82.6% was noticed. At 6 months follow-up, the overall treatment success rate was 72.2%. For patients treated with sodium stibogluconate (SSG), the treatment success rates at the end of treatment and at six-month follow-up were 81.5% and 80.7%, respectively. Multiple doses of liposomal-amphotericin B (L-AMB) had treatment success rates of 96.7 and 71–100% at the end of treatment and at 6 months follow-up, respectively. The combination of SSG with paromomycin (PM) gave treatment success rates of up to 90.1% at the end of treatment. HIV-infected individuals were found to have a higher mortality (odds ratio = 4.77, 95% CI: 1.30–17.43, P = 0.009) rate at 6 months follow-up.

Conclusions

SSG alone has shown lower treatment efficacy in the management of VL when compared to combination of SSG with PM and multiple doses of L-AMB. The combination of SSG with PM gave good treatment success rates with shorter duration of treatment. Hence, the combination of SSG with PM should be used preferentially over SSG monotherapy. Multiple doses of L-AMB showed great efficacy especially among patients with complications, severe disease, HIV co-infection, and intolerance to the adverse effects of antimonials. HIV-infected individuals had a worse prognosis than their HIV-negative counterparts.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0491-7) contains supplementary material, which is available to authorized users.

Recent Development of Visceral Leishmaniasis Treatments: Successes, Pitfalls, and Perspectives

Research in visceral leishmaniasis in the last decade has been focused on how better to use the existing medicines as monotherapy or in combination. Systematic research by geographical regions has shown that a universal treatment is far from today's reality. Substantial progress has been made in the elimination of kala-azar in South Asia, with a clear strategy on first- and second-line therapy options of single-dose liposomal amphotericin B and a combination of paromomycin and miltefosine, respectively, among other interventions. In Eastern Africa, sodium stibogluconate (SSG) and paromomycin in combination offer an advantage compared to the previous SSG monotherapy, although not exempted of limitations, as this therapy requires 17 days of painful double injections and bears the risk of SSG-related cardiotoxicity. In this region, attempts to improve the combination therapy have been unsuccessful. However, pharmacokinetic studies have led to a better understanding of underlying mechanisms, like the underexposure of children to miltefosine treatment, and an improved regimen using an allometric dosage. Given this global scenario of progress and pitfalls, we here review what steps need to be taken with existing medicines and highlight the urgent need for oral drugs. Furthermore, it should be noted that six candidates belonging to five new chemical classes are reaching phase I, ensuring an optimistic near future.

Visceral leishmaniasis relapse hazard is linked to reduced miltefosine exposure in patients from Eastern Africa: a population pharmacokinetic/pharmacodynamic study

Background

Low efficacy of miltefosine in the treatment of visceral leishmaniasis was recently observed in Eastern Africa.

Objectives

To describe the pharmacokinetics and establish a pharmacokinetic/pharmacodynamic relationship for miltefosine in Eastern African patients with visceral leishmaniasis, using a time-to-event approach to model relapse of disease.

Methods

Miltefosine plasma concentrations from 95 patients (48 monotherapy versus 47 combination therapy) were included in the population pharmacokinetic model using non-linear mixed effects modelling. Subsequently a time-to-event model was developed to model the time of clinical relapse. Various summary pharmacokinetic parameters (various AUCs, Time > EC₅₀, Time > EC₉₀), normalized within each treatment arm to allow simultaneous analysis, were evaluated as relapse hazard-changing covariates.

Results

A two-compartment population model with first-order absorption fitted the miltefosine pharmacokinetic data adequately. Relative bioavailability was reduced (−74%, relative standard error 4.7%) during the first week of treatment of the monotherapy arm but only the first day of the shorter combination regimen. Time to the relapse of infection could be described using a constant baseline hazard (baseline 1.8 relapses/year, relative standard error 72.7%). Miltefosine Time > EC₉₀ improved the model significantly when added in a maximum effect function on the baseline hazard (half maximal effect with Time > EC₉₀ 6.97 days for monotherapy).

Conclusions

Miltefosine drug exposure was found to be decreased in Eastern African patients with visceral leishmaniasis, due to a (transient) initial lower bioavailability. Relapse hazard was inversely linked to miltefosine exposure. Significantly lower miltefosine exposure was observed in children compared with adults, further urging the need for implementation of dose adaptations for children.

Chemotherapeutics of visceral leishmaniasis: present and future developments

Treatment of Visceral Leishmaniasis (VL), a neglected tropical disease, is very challenging with few treatment options. Long duration of treatment and drug toxicity further limit the target of achieving VL elimination. Chemotherapy remains the treatment of choice. Single dose of liposomal amphotericin B (LAmB) and multidrug therapy (LAmB + miltefosine, LAmB + paromomycin (PM), or miltefosine + PM) are recommended treatment regimen for treatment of VL in Indian sub-continent. Combination therapy of pentavalent antimonials (Sbv) and PM in East Africa and LAmB in the Mediterranean region/South America remains the treatment of choice. Various drugs having anti-leishmania properties are in preclinical phase and need further development. An effective treatment and secondary prophylaxis of HIV-VL co-infection should be developed to decrease treatment failure and drug resistance.

Immunomodulatory Therapy of Visceral Leishmaniasis in Human Immunodeficiency Virus-Coinfected Patients

Patients with visceral leishmaniasis (VL)–human immunodeficiency virus (HIV) coinfection experience increased drug toxicity and treatment failure rates compared to VL patients, with more frequent VL relapse and death. In the era of VL elimination strategies, HIV coinfection is progressively becoming a key challenge, because HIV-coinfected patients respond poorly to conventional VL treatment and play an important role in parasite transmission. With limited chemotherapeutic options and a paucity of novel anti-parasitic drugs, new interventions that target host immunity may offer an effective alternative. In this review, we first summarize current views on how VL immunopathology is significantly affected by HIV coinfection. We then review current clinical and promising preclinical immunomodulatory interventions in the field of VL and discuss how these may operate in the context of a concurrent HIV infection. Caveats are formulated as these interventions may unpredictably impact the delicate balance between boosting of beneficial VL-specific responses and deleterious immune activation/hyperinflammation, activation of latent provirus or increased HIV-susceptibility of target cells. Evidence is lacking to prioritize a target molecule and a more detailed account of the immunological status induced by the coinfection as well as surrogate markers of cure and protection are still required. We do, however, argue that virologically suppressed VL patients with a recovered immune system, in whom effective antiretroviral therapy alone is not able to restore protective immunity, can be considered a relevant target group for an immunomodulatory intervention. Finally, we provide perspectives on the translation of novel theories on synergistic immune cell cross-talk into an effective treatment strategy for VL–HIV-coinfected patients.

Liposomal amphotericin B in travelers with cutaneous and muco-cutaneous leishmaniasis: Not a panacea

Background

Complex cutaneous and muco-cutaneous leishmaniasis (CL and MCL) often requires systemic therapy. Liposomal amphotericin B (L-AmB) has a strong potential for a solid clinical benefit in this indication.

Methods

We conducted a retrospective analysis of data from a French centralized referral treatment program and from the “LeishMan” European consortium database. All patients with parasitologically proven CL or MCL who received at least one dose of L-AmB were included. Positive outcome was based on ulcer closure as per recent WHO workshop guidelines.

Results

From 2008 through 2016, 43 travelers returning from 18 countries (Old World n = 28; New World n = 15) were analyzed with a median follow-up duration of 79 days [range 28–803]. Main clinical forms were: localized CL with one or multiple lesions (n = 32; 74%) and MCL (n = 8; 19%). As per published criteria 19 of 41 patients (46%) were cured 90 days after one course of L-AmB. When the following items -improvement before day 90 but no subsequent follow-up, delayed healing (>3 months) and healing after a second course of L-AmB- were included in the definition of cure, 27 of 43 patients (63%) had a positive outcome. Five patients (MCL = 1; CL = 4) experienced a relapse after a median duration of 6 months [range 3–27] post treatment and 53% of patients (23/43) experienced at least one adverse event including severe hypokalaemia and acute cardiac failure (one patient each). In multivariate analysis, tegumentary infection with L. infantum was associated with complete healing after L-AmB therapy (OR 5.8 IC 95% [1.03–32]) while infection with other species had no impact on outcome.

Conclusion

In conditions close to current medical practice, the therapeutic window of L-AmB was narrow in travellers with CL or MCL, with the possible exception of those infected with L. infantum. Strict follow-up is warranted when using L-AmB in patients with mild disease.

Cutaneous and muco-cutaneous leishmaniasis (CL/MCL) are disfiguring diseases caused by a worldwide distributed parasite called Leishmania and its 20 species. Clinical manifestations span a wide continuum from single nodular lesion to disseminated form with mucosal involvement. Though local treatment with cryotherapy and intralesionnal antimony or topical formulations of paromomycin is generally adequate in most of situations, some patients with complex CL/MCL require systemic therapy. No convenient regimen has been proved to be safe and effective for all infecting species, all clinical forms and all patients (e.g. children, pregnant women, adults with comorbidities or immunosuppression). In this study, the authors examined in returning travelers with CL/MCL the effectiveness of an antifungal agent “liposomal amphotericin B” (L-AmB), which is highly effective in visceral leishmaniasis. Surprisingly, rates of healing were lower than in previous reports in this unselected population that reflects clinical practice in non-endemic countries. The observations also suggest that some Leishmania species (namely, L. infantum) may be more susceptible to L-AmB than others. Occurrence of adverse events should raises the question of the benefit-risk balance of L-AmB in CL/MCL. Careful attention to comorbidities and adoption of strict protocols for administration are pre-requisites for the use of L-AmB in patients with CL/MCL.

Short-course Regimens of Liposomal Amphotericin B for the Treatment of Mediterranean Visceral Leishmaniasis in Children: An 11-year Retrospective Study at a Tertiary Care Center

BACKGROUND

Visceral leishmaniasis (VL) remains an important public health problem in endemic regions. Current antileishmanial agents share several limitations including potentially serious side effects and the risk of clinical failure.

OBJECTIVES

Aim of this study was to examine the effectiveness and safety of short-course liposomal amphotericin B (L-AmB) regimens in the treatment of childhood VL in our area.

METHODS

The cases of 43 VL patients (20 males; 23 females; mean age: 4.6 years) treated at a tertiary children's hospital over an 11-year period were retrospectively reviewed. Diagnosis was confirmed with identification of Leishmania spp. in bone marrow samples and/or a positive serologic test. All patients were treated with 5 different L-AmB regimens at a dose of 18-22 mg/kg.

RESULTS

Initial response to treatment was attained in all patients (100%), while definitive cure at 6 months was achieved in 98% of patients. Adverse effects were recorded in 14 children and consisted mostly of infusion reactions and electrolyte disorders. Self-limiting nephrotoxicity was observed in 3 patients including a 12-year-old girl in whom acute kidney injury was developed. In addition, ventricular arrhythmias developed in a 13-year-old boy necessitating drug discontinuation. Although side effects were more frequent with the 2-day regimen, the difference with regard to toxicity between dosing regimens was not significant.

CONCLUSIONS

Short-course L-AmB regimens are effective and safe for the treatment of childhood VL in our area. Our findings suggest that large L-AmB doses can possibly account for a higher rate of adverse events including nephrotoxicity.

Efficacy and safety of available treatments for visceral leishmaniasis in Brazil: A multicenter, randomized, open label trial

Background

There is insufficient evidence to support visceral leishmaniasis (VL) treatment recommendations in Brazil and an urgent need to improve current treatments. Drug combinations may be an option.

Methods

A multicenter, randomized, open label, controlled trial was conducted in five sites in Brazil to evaluate efficacy and safety of (i) amphotericin B deoxycholate (AmphoB) (1 mg/kg/day for 14 days), (ii) liposomal amphotericin B (LAMB) (3 mg/kg/day for 7 days) and (iii) a combination of LAMB (10 mg/kg single dose) plus meglumine antimoniate (MA) (20 mg Sb⁺⁵/kg/day for 10 days), compared to (iv) standard treatment with MA (20 mg Sb⁺⁵/kg/day for 20 days). Patients, aged 6 months to 50 years, with confirmed VL and without HIV infection were enrolled in the study. Primary efficacy endpoint was clinical cure at 6 months. A planned efficacy and safety interim analysis led to trial interruption.

Results

378 patients were randomized to the four treatment arms: MA (n = 112), AmphoB (n = 45), LAMB (n = 109), or LAMB plus MA (n = 112). A high toxicity of AmphoB prompted an unplanned interim safety analysis and this treatment arm was dropped. Per intention-to-treat protocol final analyses of the remaining 332 patients show cure rates at 6 months of 77.5% for MA, 87.2% for LAMB, and 83.9% for LAMB plus MA, without statistically significant differences between the experimental arms and comparator (LAMB: 9.7%; CI95% -0.28 to 19.68, p = 0.06; LAMB plus MA: 6.4%; CI95% -3.93 to 16.73; p = 0.222). LAMB monotherapy was safer than MA regarding frequency of treatment-related adverse events (AE) (p = 0.045), proportion of patients presenting at least one severe AE (p = 0.029), and the proportion of AEs resulting in definitive treatment discontinuation (p = 0.003).

Conclusions

Due to lower toxicity and acceptable efficacy, LAMB would be a more suitable first line treatment for VL than standard treatment. ClinicalTrials.gov identification number: NCT01310738.

Trial registration

ClinicalTrials.gov NCT01310738

Visceral leishmaniasis remains a worldwide public health concern with high mortality even when proper treatment is instituted. There is a need to develop efficacious, safer and shorter treatment alternatives as the current options suffer from high toxicity and long treatment duration. Combination therapies emerge as an alternative, and WHO has encouraged the conduct of studies to evaluate drug combinations where evidence for current treatment regimens is not available. In Brazil, there is no local evidence to support the current treatment recommendations. Therefore, a clinical trial was conducted in five hospitals in Brazil to evaluate the efficacy and safety of the current available treatments—meglumine antimoniate, amphotericin B deoxycholate and liposomal amphotericin B—and of a combination of liposomal amphotericin B, single dose, and meglumine antimoniate, in a shorter administration regimen. Preliminary safety results led to the discontinuation of the amphotericin B deoxycholate treatment arm and a planned interim analysis resulted in the trial interruption. The final results, comparing liposomal amphotericin B and liposomal amphotericin B plus meglumine antimoniate to the standard meglumine antimoniate treatment, did not show a statistically significant difference in cure rates, though cure rate was higher in the liposomal amphotericin B group. Liposomal amphotericin B treatment showed a better safety profile compared to meglumine antimoniate. These results will support future changes in treatment protocols in Brazil and potentially in Latin America.

Safety and Effectiveness of Sodium Stibogluconate and Paromomycin Combination for the Treatment of Visceral Leishmaniasis in Eastern Africa: Results from a Pharmacovigilance Programme

INTRODUCTION

In 2010, WHO recommended a new first-line treatment for visceral leishmaniasis (VL) in Eastern Africa. The new treatment, a combination of intravenous (IV) or intramuscular (IM) sodium stibogluconate (SSG) and IM paromomycin (PM) was an improvement over SSG monotherapy, the previous first-line VL treatment in the region. To monitor the new treatment's safety and effectiveness in routine clinical practice a pharmacovigilance (PV) programme was developed.

METHODS

A prospective PV cohort was developed. Regulatory approval was obtained in Sudan, Kenya, Uganda and Ethiopia. Twelve sentinel sites sponsored by the Ministries of Health, Médecins Sans Frontières (MSF) and Drugs for Neglected Diseases initiative (DNDi) participated. VL patients treated using the new treatment were consented and included in a common registry that collected demographics, baseline clinical characteristics, adverse events, serious adverse events and treatment outcomes. Six-monthly periodic safety update reports (PSUR) were prepared and reviewed by a PV steering committee.

RESULTS

Overall 3126 patients were enrolled: 1962 (62.7%) from Sudan, 652 (20.9%) from Kenya, 322 (10.3%) from Ethiopia and 190 (6.1%) from Uganda. Patients were mostly male children (68.1%, median age 11 years) with primary VL (97.8%). SSG-PM initial cure rate was 95.1%; no geographical differences were noted. HIV/VL co-infected patients and patients older than 50 years had initial cure rates of 56 and 81.4%, respectively, while 1063 (34%) patients had at least one adverse event (AE) during treatment and 1.92% (n = 60) had a serious adverse event (SAE) with a mortality of 1.0% (n = 32). There were no serious unexpected adverse drug reactions.

CONCLUSIONS

This first regional PV programme in VL supports SSG-PM combination as first-line treatment for primary VL in Eastern Africa. SSG-PM was effective and safe except in HIV/VL co-infected or older patients. Active PV surveillance of targeted safety, effectiveness and key VL outcomes such us VL relapse, PKDL and HIV/VL co-infection should continue and PV data integrated to national and WHO PV databases.

Liposomal Amphotericin B (AmBisome(®)): A Review of the Pharmacokinetics, Pharmacodynamics, Clinical Experience and Future Directions

Liposomal amphotericin B (AmBisome(®); LAmB) is a unique lipid formulation of amphotericin B. LAmB is a standard of care for a wide range of medically important opportunistic fungal pathogens. LAmB has a significantly improved toxicity profile compared with conventional amphotericin B deoxycholate (DAmB). Despite nearly 20 years of clinical use, the pharmacokinetics and pharmacodynamics of this agent, which differ considerably from DAmB, remain relatively poorly understood and underutilized in the clinical setting. The molecular pharmacology, preclinical and clinical pharmacokinetics, and clinical experience with LAmB for the most commonly encountered fungal pathogens are reviewed. In vitro, experimental animal models and human clinical trial data are summarized, and novel routes of administration and dosing schedules are discussed. LAmB is a formulation that results in reduced toxicity as compared with DAmB while retaining the antifungal effect of the active agent. Its long terminal half-life and retention in tissues suggest that single or intermittent dosing regimens are feasible, and these should be actively investigated in both preclinical models and in clinical trials. Significant gaps remain in knowledge of pharmacokinetics and pharmacodynamics in special populations such as neonates and children, pregnant women and obese patients.

Effectiveness of Short-Course Meglumine Antimoniate (Glucantime®) for Treatment of Visceral Leishmaniasis: A 13-Year, Multistage, Non-Inferiority Study in Iran

The World Health Organization's (WHO) recommendation is 28-day course of meglumine antimoniate (Glucantime^®, Sanofi Aventis, France) for the treatment of visceral leishmaniasis (VL). The aim of this study was to evaluate the effectiveness of a shorter duration of treatment in regions with low level of resistance to Glucantime. During 13 years, this study was conducted in three phases on 392 patients. In the pilot first phase, we performed splenic punctures in seven patients to assess the correlation between the changes in the parasite load during treatment with Glucantime and defervescence. With defervescence, parasite density was dramatically dropped (P = 0.014), propounding defervescence as a marker of parasitological response. On the basis of the results, we conducted a randomized trial on 75 patients, comparing the efficacy of continuation of Glucantime therapy for 1, 2, or 3 weeks after defervescence. The treatment course of 1 week after defervescence (mean = 11.7 days) was non-inferior to that of 3 weeks (final cure rate, 96% versus 100%; P = 0.023). The third phase was a retrospective cohort study of 302 patients treated either with the WHO's regimen or for 7 days after defervescence (intervention group). Relapse was detected in 8.3% patients of the intervention group and in 5% patients following the WHO's regimen (P = 0.006 for non-inferiority). The final duration of treatment in intervention group was significantly shorter than standard course (13.3 ± 2.6 versus 28 days; P < 0.001). In summary, treatment of VL with Glucantime for 1 week after defervescence was non-inferior to and appears to be an acceptable alternative to the standard 28-day course for patients in Iran who show a response to antimonial therapy.

Diagnosis and Treatment of Leishmaniasis: Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA) and the American Society of Tropical Medicine and Hygiene (ASTMH)

It is important to realize that leishmaniasis guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. The IDSA and ASTMH consider adherence to these guidelines to be voluntary, with the ultimate determinations regarding their application to be made by the physician in the light of each patient's individual circumstances.

Safety and efficacy of liposomal amphotericin B for treatment of complicated visceral leishmaniasis in patients without HIV, North-West Ethiopia

Background

Visceral leishmaniasis (VL) is a protozoan disease that is invariably fatal if left untreated. The disease is found in 70 countries with incidence of 0.2 – 0.4 million cases. The mainstay of treatment in resource limited countries like Ethiopia is antimonials, while use of liposomal amphotericin B is reserved for treatment of complicated VL cases. The aim of this study was to assess the safety and efficacy of liposomal amphotericin B in HIV negative VL patients diagnosed with complications.

Methods

A retrospective chart review was conducted involving records of patients admitted between January 2009 and December 2014. Baseline sociodemographic, clinical, and treatment outcome data were collected. The doses of liposomal amphotericin B and adverse events related to treatment were retrieved. Categorical and continuous variables respectively were analyzed by Chi-square and Mann–Whitney U tests. A p-value of less than 0.05 was considered statistically significant.

Results

A total of 147 patients with severe VL were treated with liposomal amphotericin B in total dose ranges of 20 mg/kg to 35 mg/kg. In the overall treatment outcome analysis, initial cure (30 days after start of treatment) was observed in 128 (87.1 %), treatment failures in 10 (6.8 %), interruptions in 2(1.4 %) and deaths in 7 (4.8 %) patients. Initial cure rate at high dose (24-35 mg/kg total dose) was 96.7 % (59/61) versus 80.2 % (69/86) at lower doses (<24 mg/kg); which was significantly higher (P < 0.01), OR = 4.56: 95 %, Confidence Interval (CI) = 1.17 – 20.78). Ten cases (11.8 %) of treatment failure occurred in the low dose treatment group. The most common adverse events (AEs) were hypokalemia in 39 cases (26.5 %) and infusion related reactions in 16 (10.9 %). The frequency of hypokalemia and infusion related reactions were not significantly different between the low and high dose liposomal amphotericin B.

Conclusion

In HIV negative complicated VL patients, high dose of liposomal amphotericin B was found to have high cure rate at the end of treatment. The appropriate dose for better efficacy needs to be determined. Monitoring serum potassium level during treatment with liposomal amphotericin B should be an essential component of the clinical management of VL.

Progress in the Mathematical Modelling of Visceral Leishmaniasis

The leishmaniases comprise a complex of diseases characterized by clinical outcomes that range from self-limiting to chronic, and disfiguring and stigmatizing to life threatening. Diagnostic methods, treatments, and vector and reservoir control options exist, but deciding the most effective interventions requires a quantitative understanding of the population level infection and disease dynamics. The effectiveness of any set of interventions has to be determined within the context of operational conditions, including economic and political commitment. Mathematical models are the best available tools for studying quantitative systems crossing disciplinary spheres (biology, medicine, economics) within environmental and societal constraints. In 2005, the World Health Assembly and government health ministers of India, Nepal, and Bangladesh signed a Memorandum of Understanding to eliminate the life threatening form of leishmaniasis, visceral leishmaniasis (VL), on the Indian subcontinent by 2015 through a combination of early case detection, improved treatments, and vector control. The elimination target is <1 case/10,000 population at the district or subdistrict level compared to the current 20/10,000 in the regions of highest transmission. Towards this goal, this chapter focuses on mathematical models of VL, and the biology driving those models, to enable realistic predictions of the best combination of interventions. Several key issues will be discussed which have affected previous modelling of VL and the direction future modelling may take. Current understanding of the natural history of disease, immunity (and loss of immunity), and stages of infection and their durations are considered particularly for humans, and also for dogs. Asymptomatic and clinical infection are discussed in the context of their relative roles in Leishmania transmission, as well as key components of the parasite-sandfly-vector interaction and intervention strategies including diagnosis, treatment and vector control. Gaps in current biological knowledge and potential avenues to improve model structures and mathematical predictions are identified. Underpinning the marriage between biology and mathematical modelling, the content of this chapter represents the first step towards developing the next generation of models for VL.

Efficacy and Safety of AmBisome in Combination with Sodium Stibogluconate or Miltefosine and Miltefosine Monotherapy for African Visceral Leishmaniasis: Phase II Randomized Trial

Background

SSG&PM over 17 days is recommended as first line treatment for visceral leishmaniasis in eastern Africa, but is painful and requires hospitalization. Combination regimens including AmBisome and miltefosine are safe and effective in India, but there are no published data from trials of combination therapies including these drugs from Africa.

Methods

A phase II open-label, non-comparative randomized trial was conducted in Sudan and Kenya to evaluate the efficacy and safety of three treatment regimens: 10 mg/kg single dose AmBisome plus 10 days of SSG (20 mg/kg/day), 10 mg/kg single dose AmBisome plus 10 days of miltefosine (2.5mg/kg/day) and miltefosine alone (2.5 mg/kg/day for 28 days). The primary endpoint was initial parasitological cure at Day 28, and secondary endpoints included definitive cure at Day 210, and pharmacokinetic (miltefosine) and pharmacodynamic assessments.

Results

In sequential analyses with 49–51 patients per arm, initial cure was 85% (95% CI: 73–92) in all arms. At D210, definitive cure was 87% (95% CI: 77–97) for AmBisome + SSG, 77% (95% CI 64–90) for AmBisome + miltefosine and 72% (95% CI 60–85) for miltefosine alone, with lower efficacy in younger patients, who weigh less. Miltefosine pharmacokinetic data indicated under-exposure in children compared to adults.

Conclusion

No major safety concerns were identified, but point estimates of definitive cure were less than 90% for each regimen so none will be evaluated in Phase III trials in their current form. Allometric dosing of miltefosine in children needs to be evaluated.

Trial Registration

The study was registered with ClinicalTrials.gov, number NCT01067443

Visceral leishmaniasis, or kala-azar, is a parasitic disease which is fatal without treatment. A 17-day treatment of sodium stibogluconate (SSG) with paromomycin (PM) is the recommended treatment in eastern Africa, but requires painful injections, causes adverse events, and patients need to stay in the hospital during treatment. An affordable, safe and effective oral treatment would be preferable. Whilst research to identify entirely new drugs is underway, existing treatments are being optimized as a short-term solution. Combination regimens based on AmBisome and miltefosine have been shown to be safe and effective in treating Indian patients, but there are no published data from use of these drugs in combination regimens from Africa, where efficacy of treatments can be different from India. Three regimens were evaluated for treating VL in eastern Africa, using AmBisome in combination with SSG or miltefosine, or miltefosine alone. Once again, drugs which are effective in India were found to be less so in African patients, and none of the regimes tested showed sufficiently high definitive cure rates to evaluate in Phase III trials. The results also suggest miltefosine was under-dosed in children and so allometric dosing, which takes into account the differences in drug metabolism seen in children compared to adults, needs to be studied.

The Leishmaniasis East Africa Platform (LEAP): strengthening clinical trial capacity in resource-limited countries to deliver new treatments for visceral leishmaniasis

Visceral leishmaniasis is a neglected tropical disease endemic in East Africa where improved patient-adapted treatments are needed. The Leishmaniasis East Africa Platform (LEAP) was created in 2003 to strengthen clinical research capacity, serve as a base for training, and evaluate and facilitate implementation of new treatments. Major infrastructure upgrades and personnel training have been carried out. A short course of Sodium Stibogluconate and Paramomycin (SSG&PM) was evaluated and is now first-line treatment in the region; alternative treatments have also been assessed. LEAP can serve as a successful model of collaboration between different partners and countries when conducting clinical research in endemic countries to international standards.

Visceral leishmaniasis: a forgotten epidemic

Visceral leishmaniasis (VL or kala-azar) is most endemic in Asia and Africa and commonly affects young children. It is usually caused by Leishmania donovani or Leishmania infantum that are transmitted by Phlebotomine sand flies. Transmission may be anthroponotic or zoonotic or both, depending on the endemic area. Clinical features include fever, hepatosplenomegaly, weight loss and pancytopenia. Younger age, malnutrition and immunosuppression (HIV infection, use of immunosuppressive drugs) are risk factors. Many infections remain asymptomatic. Diagnosis is made by demonstration of the Leishmania parasite in aspirates of lymph node, bone marrow or spleen. Serological tests such as rK39 strip test are widely used but the sensitivity varies. qPCR is useful to detect low numbers of parasites and to monitor treatment. Treatment is with AmBisome monotherapy in most areas but with drug combinations elsewhere. HIV co-infected patients are most difficult to treat and often relapse. Control efforts focus on case finding, availability of diagnostic tools, reservoir control and protection from sand flies (insecticides, bed nets). There is no human vaccine.

Recent developments and future prospects in the treatment of visceral leishmaniasis

Limited therapeutic options in visceral leishmaniasis (VL) make the treatment of this neglected disease very challenging. In addition to this, long treatment duration and toxic adverse effects make it even more difficult. With no effective vaccine available to date, treatment of VL is based only on chemotherapy. In the Indian subcontinent, a single dose of liposomal amphotericin B (L-AmB) and multidrug therapy (L-AmB + miltefosine, L-AmB + paromomycin [PM], or miltefosine + PM) are the treatments of choice for VL. In East Africa, however, combination therapy of pentavalent antimonials (Sb(v)) and PM remains the treatment of choice, and in the Mediterranean region and South America, L-AmB is the recommended drug. Fexinidazole and PA-824 are new promising drugs which have shown encouraging results in preclinical studies.

Successful Treatment of Human Visceral Leishmaniasis Restores Antigen-Specific IFN-γ, but not IL-10 Production

One of the key immunological characteristics of active visceral leishmaniasis (VL) is a profound immunosuppression and impaired production of Interferon-γ (IFN-γ). However, recent studies from Bihar in India showed using a whole blood assay, that whole blood cells have maintained the capacity to produce IFN-γ. Here we tested the hypothesis that a population of low-density granulocytes (LDG) might contribute to T cell responses hyporesponsiveness via the release of arginase. Our results show that this population is affected by the anticoagulant used to collect blood: the frequency of LDGs is significantly lower when the blood is collected with heparin as compared to EDTA; however, the anticoagulant does not impact on the levels of arginase released. Next, we assessed the capacity of whole blood cells from patients with active VL to produce IFN-γ and IL-10 in response to antigen-specific and polyclonal activation. Our results show that whole blood cells produce low or levels below detection limit of IFN-γ and IL-10, however, after successful treatment of VL patients, these cells gradually regain their capacity to produce IFN-γ, but not IL-10, in response to activation. These results suggest that in contrast to VL patients from Bihar, India, whole blood cells from VL patients from Gondar, Ethiopia, have lost their ability to produce IFN-γ during active VL and that active disease is not associated with sustained levels of IL-10 production following stimulation.

The leishmaniases, a group of diseases caused by Leishmania parasites, belong to the most neglected tropical diseases: they are mainly found in low-income countries and affect the poorest populations. These parasites infect cells of the immune system called macrophages, which can kill the intracellular parasites in response to soluble mediators they receive from other cells of the immune system, the lymphocytes. Visceral leishmaniasis is the most severe form of the leishmaniases and is characterized by enlarged liver and spleen, fever, weight-loss and anaemia and represents a major public health problem in Ethiopia. Currently there is no vaccine available, the existing treatment has many severe side effects and drug-resistance is increasing. In the present study, we worked with patients suffering from visceral leishmaniasis. This form of the disease is fatal if the patients are not treated. We studied the ability of lymphocytes isolated from their blood to produce soluble mediators before and at different times after the end of treatment. Our results show that the lymphocytes have an impaired capacity to produce the soluble mediator required to instruct infected cells to kill the intracellular parasites, but that this lack of response is gradually restored with time after successful treatment.

Combined Immune Therapy for the Treatment of Visceral Leishmaniasis

Chronic disease caused by infections, cancer or autoimmunity can result in profound immune suppression. Immunoregulatory networks are established to prevent tissue damage caused by inflammation. Although these immune checkpoints preserve tissue function, they allow pathogens and tumors to persist, and even expand. Immune checkpoint blockade has recently been successfully employed to treat cancer. This strategy modulates immunoregulatory mechanisms to allow host immune cells to kill or control tumors. However, the utility of this approach for controlling established infections has not been extensively investigated. Here, we examined the potential of modulating glucocorticoid-induced TNF receptor-related protein (GITR) on T cells to improve anti-parasitic immunity in blood and spleen tissue from visceral leishmaniasis (VL) patients infected with Leishmania donovani. We found little effect on parasite growth or parasite-specific IFNγ production. However, this treatment reversed the improved anti-parasitic immunity achieved by IL-10 signaling blockade. Further investigations using an experimental VL model caused by infection of C57BL/6 mice with L. donovani revealed that this negative effect was prominent in the liver, dependent on parasite burden and associated with an accumulation of Th1 cells expressing high levels of KLRG-1. Nevertheless, combined anti-IL-10 and anti-GITR mAb treatment could improve anti-parasitic immunity when used with sub-optimal doses of anti-parasitic drug. However, additional studies with VL patient samples indicated that targeting GITR had no overall benefit over IL-10 signaling blockade alone at improving anti-parasitic immune responses, even with drug treatment cover. These findings identify several important factors that influence the effectiveness of immune modulation, including parasite burden, target tissue and the use of anti-parasitic drug. Critically, these results also highlight potential negative effects of combining different immune modulation strategies.

Sodium stibogluconate and paromomycin for treating visceral leishmaniasis under routine conditions in eastern Sudan

OBJECTIVES

Among patients with primary and relapse visceral leishmaniasis (VL) in eastern Sudan, we determined the proportion eligible for treatment with sodium stibogluconate and paromomycin (SSG/PM) and, of these, their demographic and clinical characteristics; initial treatment outcomes including adverse side effects requiring treatment discontinuation; treatment outcomes by 6 months; and risk factors associated with initial (slow responders) and late treatment failure (relapses and post-kala-azar dermal leishmaniasis, PKDL).

METHODS

A retrospective cohort study in Tabarak Allah Hospital, Gedaref Province, eastern Sudan, from July 2011 to January 2014.

RESULTS

Of 1252 individuals diagnosed with VL (1151 primary and 101 relapses), 65% were eligible for SSG/PM including 83% children, almost half of them malnourished and anaemic. About 4% of individuals discontinued treatment due to side effects; 0.7% died during treatment. Initial cure was achieved in 93% of 774 primary cases and 77% of 35 relapse cases (P < 0.001). Among the 809 patients eligible for SSG/PM, 218 (27%) were lost to follow-up. Outcomes by six months among the 591 patients with available follow-up data were: definitive cure (n = 506; 86%), relapse (n = 38; 6%), treatment discontinuation (n = 33; 6%), PKDL (n = 7; 1%) and death (n = 7; 1%). Among those completing a full course of SSG/PM, relapses and under-fives were at significantly higher risk of early and late treatment failure, respectively.

CONCLUSION

Whether SSG/PM as a first-line regimen is an undeniable progress compared to SSG monotherapy, it excluded a considerable proportion of VL patients due to drug safety concerns. We call for accelerated development of new drugs and treatment regimens to improve VL treatment in Sudan.

Short-Course Treatment Regimen of Indian Visceral Leishmaniasis with an Indian Liposomal Amphotericin B Preparation (Fungisome™)

India bears the burden of about half of global visceral leishmaniasis (VL) cases with emerging problems of stibanate resistance. Liposomal preparations have improved treatment outcome through shorter duration of therapy and lower toxicity compared with conventional amphotericin B. We report the efficacy of two short-course regimens of an Indian preparation of liposomal amphotericin B (Fungisome™) for VL caused by Leishmania donovani in India. An open-label, randomized, single-center comparative study was undertaken from 2008 to 2011, involving 120 treatment naive non-human immunodeficiency virus VL patients randomly allocated to two groups. Fungisome™ was given, in groups A (N = 60), 5 mg/kg daily for 2 days and B (N = 60), 7.5 mg/kg daily for 2 days, as intravenous infusion. Initial cure rate was 100% in both the groups after 1 month posttreatment. At 6 months after completion of treatment, definitive cure rate was group A 90% (54/60, 95% confidence interval (CI): 80.55-95.72%); group B: 100% (95% CI: 95.92-100%); (P = 0.027). No serious adverse events occurred in either group. The short-course, 2-day regimen of 15 mg/kg Fungisome™ infusion is easy to administer, effective, and safe for treatment of VL caused by L. donovani in India.