Randomized, Double-Blind Clinical Trial of Topical Imiquimod 5% with Parenteral Meglumine Antimoniate in the Treatment of Cutaneous Leishmaniasis in Peru

Malaria vaccine adjuvants: latest update and challenges in preclinical and clinical research

There is no malaria vaccine currently available, and the most advanced candidate has recently reported a modest 30% efficacy against clinical malaria. Although many efforts have been dedicated to achieve this goal, the research was mainly directed to identify antigenic targets. Nevertheless, the latest progresses on understanding how immune system works and the data recovered from vaccination studies have conferred to the vaccine formulation its deserved relevance. Additionally to the antigen nature, the manner in which it is presented (delivery adjuvants) as well as the immunostimulatory effect of the formulation components (immunostimulants) modulates the immune response elicited. Protective immunity against malaria requires the induction of humoral, antibody-dependent cellular inhibition (ADCI) and effector and memory cell responses. This review summarizes the status of adjuvants that have been or are being employed in the malaria vaccine development, focusing on the pharmaceutical and immunological aspects, as well as on their immunization outcomings at clinical and preclinical stages.

Adjuvants for Leishmania vaccines: from models to clinical application

Two million new cases of leishmaniasis occur every year, with the cutaneous leishmaniasis (CL) presentation accounting for approximately two-thirds of all cases. Despite the high incidence rates and geographic expansion of the disease, CL remains a neglected tropical disease without effective intervention strategies. Efforts to address this deficit have given rise to the experimental murine model of CL. By virtue of its simplicity and pliability, the CL model has been used to provide substantial information regarding cellular immunity, as well as in the discovery and evaluation of various vaccine adjuvants. The CL model has facilitated in vivo studies of the mechanism of action of many adjuvants, including the TLR4 agonist monophosphoryl lipid A, the TLR7/8 agonist imiquimod, the TLR9 agonist CpG, adenoviral vectors, and the immunostimulatory complexes. Together, these studies have helped to unveil the requirement for certain types of immune responses at specific stages of CL disease and provide a basis to aid the design of effective second-generation vaccines for human CL. This review focuses on adjuvants that have been tested in experimental CL, outlining how they have helped advance our understanding of the disease and ultimately, how they have performed when applied within clinical trials against human CL.

Advances in the use of topical imiquimod to treat dermatologic disorders

Imiquimod (IQ) is an immune-response modifying agent, first approved by FDA for the topical treatment of external genital and perianal warts in 1997. It induces, through stimulation of Toll-like receptors (TLRs) localized on the surface of antigen-presenting cells, synthesis and release of several endogenous pro-inflammatory cytokines such as interferon-α (IFN-α), tumor necrosis factor-α (TNF-α) and interleukins (IL) 6 and 12, which in turn stimulate both the innate and acquired immune pathways, resulting in upregulation of natural antiviral and antitumor activity. IQ 5% cream has been used for the treatment of a wide variety of dermatologic conditions in which the immune system is thought to play a role in regression of the disease. In some disorders, such as genital and perianal warts, actinic keratoses, basal cell carcinomas, Bowen’s disease and molluscum contagiosum, relative safety and efficacy are supported by randomized controlled trials of IQ. However, it is common for patients to experience local skin reactions, which can range from mild to severe in intensity, but usually resolve 1–2 weeks after interrupting treatment. Additional randomized trials are encouraged to assess safety and efficacy of IQ in the treatment of an even wider range of cutaneous disorders.

Targeting of Toll-like receptors: a decade of progress in combating infectious diseases

Toll-like receptors (TLRs) recognise highly conserved molecular structures, collectively known as pathogen-associated molecular patterns. In the past two decades, development and clinical implementation of TLR ligands-ie, chemically modified synthetic derivatives of naturally occurring ligands and fully synthetic small molecules-have been topics of intense research. Targeted manipulation of TLR signalling has been applied clinically to boost vaccine effectiveness, promote a robust T helper 1-predominant immune response against viral infection, or dampen the exaggerated inflammatory response to bacterial infection. Use of these new therapeutic molecules as adjuncts to conventional pharmacotherapy or stand-alone treatments might offer solutions to unmet clinical needs or could replace existing partly effective therapeutic strategies.

Avanços no tratamento da leishmaniose tegumentar do novo mundo nos últimos dez anos: uma revisão sistemática da literatura

INTRODUÇÃO: O arsenal terapêutico contra a leishmaniose tegumentar é muito restrito. Os antimoniais pentavalentes permanecem como as drogas de escolha para seu tratamento há mais de 50 anos. Apesar da sua eficácia, necessita de injeções diárias, apresenta muitos efeitos colaterais e tempo de cura prolongado. OBJETIVO: Realizar uma revisão sistemática da literatura sobre os avanços no tratamento da leishmaniose tegumentar do novo mundo nos últimos dez anos. METODOLOGIA: Realizou-se em junho de 2009 uma busca eletrônica nas bases de dados Pubmed, LILACS e na biblioteca eletrônica Scielo. As palavras de busca em inglês foram: "cutaneous", "leishmaniasis" e "treatment". Foram incluÃdos apenas ensaios clÃnicos randomizados, duplo-cegos, placebo controlados. Utilizou-se a escala de Jadad para avaliar a qualidade dos estudos selecionados. RESULTADOS: Segundo os critérios de inclusão e exclusão, apenas 8 artigos foram selecionados. As drogas avaliadas nos estudos selecionados foram Glucantime®, miltefosine, imunoterapia, imiquimod, rhGM-CSF, pentoxifilina e paramomicina. CONCLUSÃO: Apesar de a leishmaniose tegumentar ser um importante problema de saúde pública, os dados publicados sobre o uso de novas drogas para o tratamento da leishmaniose tegumentar em nosso meio ainda são bastante limitados

Evaluation of imiquimod for topical treatment of vaccinia virus cutaneous infections in immunosuppressed hairless mice

Imiquimod is an immune response modifier prescribed as a topical medication for a number of viral and neoplastic conditions. We evaluated the antiviral activity of imiquimod against vaccinia virus (WR strain) cutaneous infections in immunosuppressed (with cyclophosphamide) hairless mice when administered after virus exposure. Primary lesions progressed in severity, satellite lesions developed, and infection eventually killed the mice. Once daily topical treatment with 1% imiquimod cream for 3, 4, or 5 days were compared to twice daily topical treatment with 1% cidofovir cream for 7 days. Survival time of mice in all treated groups was significantly prolonged compared to placebo controls. The mean day of death for the placebo group, 3-day imiquimod, 4-day imiquimod, 5-day imiquimod, and cidofovir groups were 15.5, 20.0, 20.5, 19.5, and 20.5 days post-infection, respectively. All treatment groups showed significant reductions in primary lesion size and in the number of satellite lesions. The cidofovir and 4-day imiquimod treatments delayed the appearance of lung virus titers by 3 and 6 days, respectively, although cutaneous lesion and snout virus titers were not as affected by treatment. Benefits in survival and lesion reduction were observed when imiquimod treatment was delayed from 24, 48, and 72 h post-infection. However, increasing the treatment dose of imiquimod from 1% to 5% led to a significant decrease in antiviral efficacy. These results demonstrate the protective effects of topically administered imiquimod against a disseminated vaccinia virus infection in this mouse model.

New World cutaneous leishmaniasis: updated review of current and future diagnosis and treatment

BACKGROUND

Cutaneous leishmaniasis (CL) has traditionally been underrecognized and underreported. Improved awareness is warranted as the number of cases has increased as a result of increased travel to endemic countries, the HIV/AIDS pandemic, and the larger number of military and contract workers deployed overseas.

OBJECTIVE

We sought to present a systematic review of evidence from a gamut of research trials on the treatment efficacy of different regimens and aggregate this knowledge for use as a guide for clinical practice decisions.

METHODS

We performed a comprehensive search of print and electronic sources to identify the accumulated research information on New World CL.

RESULTS

Topical treatment of New World CL lesions is generally not recommended. Findings support the systemic administration of pentavalent antimonials as first-line treatment. Exception to this is infection with L guyanensis in French Guiana where systemic pentamidine is suggested as first-line treatment.

LIMITATIONS

The reliability of the findings of this review of research evidence is dependent on the individual quality and potential bias in its component principal trials. There was a conscious attempt to only include evidence derived from randomized controlled studies, with adequate randomization, adequate patient numbers, and complete follow-up information. However, because of the relatively small number of such studies on New World CL, evidence from nonrandomized studies and case series studies was also considered.

CONCLUSIONS

The pentavalent antimony compounds remain the first-line treatment choice for the treatment of New World CL. Concerns with cost, availability, poor compliance, and systemic toxicity, however, may compel clinicians to opt for alternative treatment modalities. Some advances in the development of an antileishmanial vaccine have been made but none is yet available for clinic use. The increase, over recent years, in the incidence of CL warrants an enhanced effort to increase awareness of the disease, assure timely diagnosis, and implement effective management and treatment strategies.

Cutaneous and mucocutaneous leishmaniasis

Leishmaniasis is a cluster of diseases caused by protozoa in the genus Leishmania. There are three basic clinical forms: cutaneous, mucocutaneous, and visceral leishmaniasis. The present review focuses on the diagnosis and treatment of cutaneous and mucocutaneous leishmaniasis. Characteristics of both the human host and the parasite species influence the clinical disease manifestations that range from asymptomatic exposure, to self-healing skin ulcers, to life-threatening widespread destructive ulcerations. Whether through medical treatment or through spontaneous resolution, skin ulcerations generally result in disfiguring scars with significant social and economic impact. Tests to confirm the diagnosis should be performed on patients who have recently visited endemic areas and have skin or mucosal manifestations consistent with leishmaniasis. Treatment depends on the species of Leishmania and the risk of widespread or disfiguring disease. Because of increasing trends in global travel, educating health care providers to recognize and treat leishmaniasis in both endemic and non-endemic countries is imperative.

Tropical medicine rounds: Treatment of Old World cutaneous leishmaniasis with dapsone, itraconazole, cryotherapy, and imiquimod, alone and in combination

BACKGROUND

Cutaneous leishmaniasis (CL) is a major public health problem. The currently available therapies are expensive, not freely available, toxic, and not always curative. A simple, effective, noninvasive therapeutic approach is required for the treatment of CL.

AIMS

To determine the clinical patterns of CL and to report our experience in the management of CL.

METHODS

One hundred and ten patients with CL seen between January 2005 and December 2007 were included in this study. The diagnosis was based on clinical features, parasitologic diagnosis, histopathology, and culture. Each patient was treated according to disease severity with either topical (cryotherapy or imiquimod) or systemic (itraconazole or dapsone) monotherapy, or a combination of these modalities.

RESULTS

CL was more common in adult expatriate men, with the upper limbs as the most commonly affected site. Noduloulcerative CL was the most common presentation (84.6%). Atypical CL was found in 18 patients. Skin biopsy was the most common diagnostic technique (66.6%). Monotherapy showed an overall success rate of 56.41%, whereas combination therapy was successful in 69.56% of cases. Cryotherapy alone was successful in 68.18% of cases. Imiquimod alone was ineffective.

CONCLUSION

A stepwise approach represents a rational and practical way of confirming CL. A combination of itraconazole/dapsone and topically applied imiquimod is safe, simple, and effective for the treatment of CL. More studies are needed to establish the role of such an approach. Cryotherapy is also safe, simple and effective for the treatment of CL.

Adjuvants for malaria vaccines

There is a renewed enthusiasm about subunit vaccines for malaria coincident with the formation of new alliances and partnerships raising international public awareness, attracting increased resources and the re-focusing of research programs on adjuvant development for infectious disease vaccines. It is generally accepted that subunit vaccines for malaria will require adjuvants to induce protective immune responses, and availability of suitable adjuvants has in the past been a barrier to the development of malaria vaccines. Several novel adjuvants are now in licensed products or in late stage clinical development, while several others are in the earlier development pipeline. Successful vaccine development requires knowing which adjuvants to use and knowing how to formulate adjuvants and antigens to achieve stable, safe, and immunogenic vaccines. For the majority of vaccine researchers this information is not readily available, nor is access to well-characterized adjuvants. In this minireview, we outline the current state of adjuvant research and development as it pertains to effective malaria vaccines.

First-line therapy for human cutaneous leishmaniasis in Peru using the TLR7 agonist imiquimod in combination with pentavalent antimony

Background

Current therapies for cutaneous leishmaniasis are limited by poor efficacy, long-term course of treatment, and the development of resistance. We evaluated if pentavalent antimony (an anti-parasitic drug) combined with imiquimod (an immunomodulator) was more effective than pentavalent antimony alone in patients who had not previously been treated.

Methods

A randomized double-blind clinical trial involving 80 cutaneous leishmaniasis patients was conducted in Peru. The study subjects were recruited in Lima and Cusco (20 experimental and 20 control subjects at each site). Experimental arm: Standard dose of pentavalent antimony plus 5% imiquimod cream applied to each lesion three times per week for 20 days. Control arm: Standard dose of pentavalent antimony plus placebo (vehicle cream) applied as above. The primary outcome was cure defined as complete re-epithelization with no inflammation assessed during the 12 months post-treatment period.

Results

Of the 80 subjects enrolled, 75 completed the study. The overall cure rate at the 12-month follow-up for the intention-to-treat analysis was 75% (30/40) in the experimental arm and 58% (23/40) in the control arm (p = 0.098). Subgroup analyses suggested that combination treatment benefits were most often observed at the Cusco site, where L. braziliensis is the prevalent species. Over the study period, only one adverse event (rash) was recorded, in the experimental arm.

Conclusion

The combination treatment of imiquimod plus pentavalent antimony performed better than placebo plus pentavalent antimony, but the difference was not statistically significant.

Trial Registration

Clinical Trials.gov NCT00257530

Neglected tropical diseases (NTDs) are a group of tropical infections including trypanosomiasis, filariasis, schistosomiasis, onchocerciasis, leishmaniasis and other such diseases of poverty. Of the classic neglected diseases, leishmaniasis has among the highest level of morbidity and mortality. Infection with Leishmania parasites causes severe disease in humans, including fatal visceral leishmaniasis and cutaneous leishmaniasis resulting in severe scarring, often in the face. This is a difficult infection to treat because the current therapies are generally poorly effective. The present study carried out a placebo-controlled, double-blinded study to investigated whether a combined therapy with imiquimod plus pentavalent antimony was superior to the standard therapy of pentavalent antimony alone as a first-line treatment for cutaneous leishmaniasis in Peru. A higher cure rate with the combination therapy was observed, but could not be conclusively proven.

Tropical dermatology: Tropical diseases caused by protozoa

Protozoan infections are very common among tropical countries and have an important impact on public health. Leishmaniasis is the most widely disseminated protozoan infection in the world, while the trypanosomiases are widespread in both Africa and South America. Amebiasis, a less common protozoal infection, is a cause of significant morbidity in some regions. Toxoplasmosis and pneumocystosis (formerly thought to be caused by a protozoan) are worldwide parasitic infections with a very high incidence in immunocompromised patients but are not restricted to them. In the past, most protozoan infections were restricted to specific geographic areas and natural reservoirs. There are cases in which people from other regions may have come in contact with these pathogens. A common situation involves an accidental contamination of a traveler, tourist, soldier, or worker that has contact with a reservoir that contains the infection. Protozoan infections can be transmitted by arthropods, such as sandflies in the case of leishmaniasis or bugs in the case of trypanosomiases. Vertebrates also serve as vectors as in the case of toxoplasmosis and its transmission by domestic cats. The recognition of the clinical symptoms and the dermatologic findings of these diseases, and a knowledge of the geographic distribution of the pathogen, can be critical in making the diagnosis of a protozoan infection.

LEARNING OBJECTIVES

After completing this learning activity, participants should be able to recognize the significance of protozoan infections worldwide, identify the dermatologic manifestations of protozoan infections, and select the best treatment for the patient with a protozoan infection.

Interventions for American cutaneous and mucocutaneous leishmaniasis

BACKGROUND

Pentavalent antimonial drugs are the most prescribed treatment for American cutaneous and mucocutaneous leishmaniasis. Other drugs have been used with varying success.

OBJECTIVES

To assess the effects of therapeutic interventions for American cutaneous and mucocutaneous leishmaniasis.

SEARCH STRATEGY

We searched the Cochrane Skin Group Specialised Register (January 2009), the Register of Controlled Clinical Trials in The Cochrane Library (Issue 1,2009), MEDLINE (2003 to January 2009), EMBASE (2005 to January 2009), LILACS (from inception to January 2009), CINAHL (1982-May 2007) and other databases.

SELECTION CRITERIA

Randomised controlled trials (RCTs) assessing treatments for American cutaneous and mucocutaneous leishmaniasis.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data.

MAIN RESULTS

We included 38 trials involving 2728 participants. Results are based on individual studies or limited pooled analyses. There was good evidence in:Leishmania braziliensis and L. panamensis infections:Intramuscular (IM) meglumine antimoniate (MA) was better than oral allopurinol for 28 days (1RCT n=127, RR 0.39; 95% CI 0.26, 0.58). Intravenous (IV)MA for 20-days was better than 3-day and 7-day IVMA plus 15% paromomycin plus 12% methylbenzethonium chloride (PR-MBCL) or 7-day IVMA (1RCT n= 150, RR 0.24; 95% CI 0.11, 0.50; RR 0.69; 95% CI 0.53, 0.90; RR 0.64; 95% CI 0.44, 0.92 respectively). Oral allopurinol plus antimonials was better than IV antimonials (2RCT n= 168, RR 1.90; 95% CI 1.40, 2.59; I(2)=0%).L. braziliensis infections:Oral pentoxifylline plus IV sodium stibogluconate (SSG) was better than IVSSG (1RCT n= 23, RR 1.66; 95% CI 1.03, 2.69); IVMA was better than IM aminosidine sulphate (1RCT n= 38, RR 0.05; 95% CI 0.00, 0.78) and better than IV pentamidine isethionate (1RCT n= 80, RR 0.45; 95% CI 0.29, 0.71). Intramuscular MA was better than Bacillus Calmette-Guérin (1RCT n= 93, RR 0.46; 95% CI 0.32, 0.65).L .panamensis infections:Oral allopurinol was better than IVMA (1RCT n= 58, RR 2.20; 95% CI 1.34, 3.60). Aminosidine sulphate at doses of 12 mg/kg/day and 18 mg/kg/day for 14 days were better than aminosidine sulphate 12 mg/kg/day for 7 days (1RCT n= 60, RR 0.23; 95% CI 0.07, 0.73; RR 0.23; 95% CI 0.07, 0.73 respectively). Oral ketoconazole for 28 days, oral miltefosine and topical PR-MBCL were better than placebo.

AUTHORS' CONCLUSIONS

Most trials have been designed and reported so poorly that they are inconclusive. There is a need for large well conducted studies that evaluate long-term effects of current therapies to improve quality and standardization of methods.

New horizons in adjuvants for vaccine development

Over the last decade, there has been a flurry of research on adjuvants for vaccines, and several novel adjuvants are now in licensed products or in late stage clinical development. The success of adjuvants in enhancing the immune response to recombinant antigens has led many researchers to re-focus their vaccine development programs. Successful vaccine development requires knowing which adjuvants to use and knowing how to formulate adjuvants and antigens to achieve stable, safe and immunogenic vaccines. For the majority of vaccine researchers this information is not readily available, nor is access to well-characterized adjuvants. In this review, we outline the current state of adjuvant research and development and how formulation parameters can influence the effectiveness of adjuvants.

Immunization with a Toll-like receptor 7 and/or 8 agonist vaccine adjuvant increases protective immunity against Leishmania major in BALB/c mice

Activation of Toll-like receptors (TLRs) on antigen-presenting cells of the innate immune system initiates, amplifies, and directs the antigen-specific acquired immune response. Ligands that stimulate TLRs therefore represent potential vaccine adjuvants. In the present study, we determined whether imiquimod and its related compound R848, which are TLR7 and/or TLR8 agonists, represent potential vaccine adjuvants when delivered topically, subcutaneously, or intramuscularly. Using the Leishmania major infection model in BALB/c mice, vaccination with crude Leishmania antigen was not protective against subsequent challenge infection unless it was administered with R848 or a topical application of imiquimod containing cream on the skin. Subcutaneous vaccination with these adjuvants mediated a TH1 response against L. major antigen, which appeared to suppress the TH2 response following a challenge infection. Protective immunity was generated following subcutaneous vaccination but not intramuscular vaccination. These observations suggest that topically administered imiquimod or subcutaneously injected R848 represent potential vaccine adjuvants to enhance the TH1 response, which can be used with existing or new vaccine formulations.

Distinct role of MAPKAPK-2 in the regulation of TNF gene expression by Toll-like receptor 7 and 9 ligands

Toll-like receptor ligands (TLRLs) produced by various pathogens activate mitogen-activated protein kinases (MAPKs). While the dependence on p38 MAPK activation for the induction of inflammatory genes by the TLR4L, lipopolysaccharide (LPS), has been well documented, the importance of the p38 pathway in gene regulation by other TLRLs is less well understood. We have focused our analysis on two TLRLs with therapeutic potential, imidazoquinoline S28463 (TLR7L) and CpG DNA (TLR9L), to explore in detail their effects on the regulation of gene expression in macrophages. Here we report that activation of the p38 MAPK/MK2 pathway is crucial for both S28463- and CpG-induced cytokine and chemokine production. We show that the stability of TNF mRNA induced by CpG DNA and S28463 is not dependent on the p38 MAPK/MK2 pathway, in contrast to LPS-induced TNF mRNA. Using a GFP reporter construct under the control of the 3' untranslated region of the TNF gene, we demonstrate that S28463 and CpG DNA-induced MK2 signalling regulates TNF mRNA primarily at the translational level, whereas LPS-induced MK2 signalling regulates both the stability and translational efficiency of TNF mRNA. Overall, these data provide insight into distinct molecular mechanisms of gene expression regulation by different Toll-like receptor ligands.

Role of imiquimod and parenteral meglumine antimoniate in the initial treatment of cutaneous leishmaniasis

BACKGROUND

Cutaneous leishmaniasis is a serious public health problem in the developing world. The main therapeutic agent--pentavalent antimony, developed >50 years ago--is expensive, often accompanied by severe adverse effects, and complicated by the emergence of drug resistance. Better therapies are urgently needed. In the present pilot study, we compared the use of imiquimod, an immunomodulatory molecule, to the use of meglumine antimoniate alone and in combination for the initial treatment of cutaneous leishmaniasis.

MATERIALS AND METHODS

Patients with newly diagnosed cutaneous leishmaniasis were enrolled from a single referral center in Lima, Peru, from August 2005 through October 2005. Patients were randomly assigned to 1 of 3 treatment groups and received either imiquimod 7.5% cream administered topically every other day for 20 days, intravenous meglumine antimoniate administered at a dosage of 20 mg/kg per day every day for 20 days, or combination therapy with both intravenous meglumine antimoniate and imiquimod 7.5% cream. Patients were evaluated weekly and at 1 and 3 months after treatment. Patients who had healed lesions at 3 months were considered to be clinically cured.

RESULTS

Although several patients showed initial resolution of symptoms with imiquimod treatment alone, all of these patients experienced relapse after treatment discontinuation. Four (57%) of 7 patients treated with meglumine antimoniate alone and 7 (100%) of 7 patients treated with combination therapy were cured. Combination therapy was not only more effective than the other 2 treatments (P<.05) but also led to faster healing and better cosmetic results.

CONCLUSION

Combination therapy with imiquimod and meglumine antimoniate is a promising regimen for the initial treatment of cutaneous leishmaniasis that warrants additional larger studies.

Cutaneous leishmaniasis treatment

The causative species of cutaneous leishmaniasis determines the clinical features and courses, and treatments. Intralesional or systemic antimonials are the gold standard for the treatment of these diseases. However, as for visceral leishmaniasis, other therapeutic options appear promising. Paromomycin ointments are effective in Leishmania major, L. tropica, L. mexicana, and L. panamensis lesions. In L. braziliensis localized leishmaniasis, both paromomycin and imiquimod may be topically applied. Oral fluconazole and zinc sulfate are useful in L. major. Oral azithromycin, effective in vitro and in mice, needs further investigation in human leishmaniasis. On the contrary, data with oral itraconazole are disappointing. Oral miltefosine, which is very effective in visceral leishmaniasis caused by L. donovani, appears ineffective in L. major and L. braziliensis infections. Intramuscular pentamidine is required for L. guyanensis cutaneous leishmaniasis, for which systemic antimony is not effective. Liposomal amphotericin B could be an alternative to antimony in south American cutaneous leishmaniasis with mucosal involvement (especially L. braziliensis and L. guyanensis infections).

Consultative meeting to develop a strategy for treatment of cutaneous leishmaniasis. Institute Pasteur, Paris. 13-15 June, 2006

Background

A meeting was organized by Drugs for Neglected Diseases initiative (DNDi) and the Institute Pasteur (IP), Paris, to review the treatment for all forms of cutaneous leishmaniasis (CL) and to propose a strategy for the development of new efficacious and affordable treatments.

Method

The global burden of CL was discussed with respect to financial impact; relation to poverty; the stigma of CL lesions and scars (particularly in young women); lack of effective, affordable, easily implemented tools and political will and resources to implement available control tools; and lack of input from pharmaceutical and biotechnology companies to develop new drugs and vaccines.

Results

According to the experts from different endemic countries present, the financial and social burdens of CL are high, but we have limited quantitative data. The analysis of published trials indicates that the quality of most trials is poor and requires both improvement and standardization. The available drugs are inadequate. Criteria by which different CL types could be prioritized as target disease were set. These criteria included: severity of the disease; lack of response to available drugs; overall incidence and prevalence of the disease; sequelae of the disease, (including recidivans and mucosal leishmaniasis); the impact of treatment of individuals on control of transmission and lack of other major parties involved in drug development. Based on these, the anthroponotic CL and its sequel "recidivans" caused by L. tropica and CL caused by L. braziliensis and its sequel, mucosal leishmaniasis were considered to be the target diseases.

The mechanism for controlling Leishmania infection to reach a stable self healing process is a balanced immune response. Immune stimulation during chemotherapy can enhance cure. There is no adequately effective vaccine, but some encouraging results have been obtained with whole killed Leishmania parasites or imiquimod (an immuno-modulator) plus antimonials. Further studies are needed. One safety/immunogenicity clinical trial is currently ongoing with a Second Generation Vaccine (SGV).

Conclusions and recommendations

There is an urgent need for new treatments for all CL types. CL should be considered as a neglected disease and organizations, such as DNDi, should include it in their list of target diseases. It was agreed that immuno-chemotherapy (with "therapeutic" vaccines or immunomodulators) has a strong potential to make an impact as a new therapy of CL with the view of shortening/reducing duration and dose of drug treatment and preventing resistance. There is also a need for safe, affordable and efficacious new chemotherapeutics. The quality of clinical trials needs to be enhanced and standardized. Short and long-term objectives and activities were defined as a part of meeting recommendations.

Tratamento da Leishmaniose Tegumentar Americana

A leishmaniose tegumentar americana é doença infecciosa da pele e mucosa, cujo agente etiológico é um protozoário do gênero Leishmania. Seu tratamento é desafio porque as drogas disponíveis apresentam elevada toxicidade, e nenhuma delas é bastante eficaz. A recidiva, a falha terapêutica em pacientes imunodeprimidos e a resistência ao tratamento são fatores que motivam a busca de uma droga ideal.

Clinical status of agents being developed for leishmaniasis

Leishmaniasis, which exists in both visceral and cutaneous forms, is currently treated with intramuscular antimony or intravenous amphotericin B. The primary unmet need is for oral therapy. Of the several drugs in clinical development, miltefosine is unique in being an oral agent with efficacy against both forms of the disease. Sitamaquine is an oral agent with substantial but not sufficient efficacy against visceral disease. Oral fluconazole has been shown to be more effective than placebo in one instance: for Leishmania major cutaneous disease from Saudi Arabia. Paromomycin is in widespread trial. Topical paromomycin formulations are being tested for cutaneous disease, and intramuscular paromomycin is in Phase III trial for Indian visceral disease. The most likely replacements for present therapy are oral miltefosine for many of the visceral and cutaneous syndromes, intramuscular paromomycin for visceral disease and topical paromomycin for some forms of cutaneous disease.

Development of a genetic assay to distinguish between Leishmania viannia species on the basis of isoenzyme differences

BACKGROUND

Tegumentary leishmaniasis in Latin America is caused mainly by Leishmania viannia braziliensis complex parasites. L. braziliensis and Leishmania viannia peruviana are the 2 predominant Leishmania species in Peru. L. braziliensis is more virulent, because it can cause mucocutaneous leishmaniasis, known as espundia, that results in severe facial destruction. Early identification of the species that causes the initial cutaneous infection would greatly help to prevent mucocutaneous leishmaniasis, because it would allow more aggressive treatment and follow-up. However, because of the close genetic similarity of L. braziliensis and L. peruviana, there currently exists no simple assay to distinguish between these species.

METHODS

We cloned the mannose phosphate isomerase gene from both L. braziliensis and L. peruviana. It is the only known isoenzyme capable of differentiating between L. braziliensis and L. peruviana in multilocus enzyme electrophoresis. Interestingly, only a single nucleotide polymorphism was found between the mannose phosphate isomerase genes from L. braziliensis and L. peruviana, resulting in an amino acid change from threonine to arginine at amino acid 361. A polymerase chain reaction assay was developed to distinguish the single nucleotide polymorphism of the mannose phosphate isomerase gene to allow for the specific identification of L. braziliensis or L. peruviana.

RESULTS

This assay was validated with 31 reference strains that were previously typed by multilocus enzyme electrophoresis, successfully applied to patient biopsy samples, and adapted to a real-time polymerase chain reaction assay.

CONCLUSIONS

This innovative approach combines new genetic knowledge with traditional biochemical fundamentals of multilocus enzyme electrophoresis to better manage leishmaniasis in Latin America.

Advances in leishmaniasis

Governed by parasite and host factors and immunoinflammatory responses, the clinical spectrum of leishmaniasis encompasses subclinical (inapparent), localised (skin lesions), and disseminated infection (cutaneous, mucosal, or visceral). Symptomatic disease is subacute or chronic and diverse in presentation and outcome. Clinical characteristics vary further by endemic region. Despite T-cell-dependent immune responses, which produce asymptomatic and self-healing infection, or appropriate treatment, intracellular infection is probably life-long since targeted cells (tissue macrophages) allow residual parasites to persist. There is an epidemic of cutaneous leishmaniasis in Afghanistan and Pakistan and of visceral infection in India and Sudan. Diagnosis relies on visualising parasites in tissue or serology; culture and detection of parasite DNA are useful in the laboratory. Pentavalent antimony is the conventional treatment; however, resistance of visceral infection in India has spawned new treatment approaches--amphotericin B and its lipid formulations, injectable paromomycin, and oral miltefosine. Despite tangible advances in diagnosis, treatment, and basic scientific research, leishmaniasis is embedded in poverty and neglected. Current obstacles to realistic prevention and proper management include inadequate vector (sandfly) control, no vaccine, and insufficient access to or impetus for developing affordable new drugs.