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

Immunotherapeutic Strategies as Potential Treatment Options for Cutaneous Leishmaniasis

Cutaneous leishmaniasis (CL), caused by protozoan parasites of the Leishmania genus, is prevalent in tropical and subtropical regions, with important morbidity, particularly in low- to middle-income countries. Current systemic treatments, including pentavalent antimonials and miltefosine, are associated with significant toxicity, reduced efficacy, and are frequently ineffective in cases of severe or chronic CL. Immunotherapies leverage the immune system to combat microbial infection and offer a promising adjunct or alternative approach to the current standard of care for CL. However, the heterogeneous clinical presentation of CL, which is dependent on parasite species and host immunity, may require informed clinical intervention with immunotherapies. This review explores the clinical and immunological characteristics of CL, emphasising the current landscape of immunotherapies in in vivo models and clinical studies. Such immune-based interventions aim to modulate immune responses against Leishmania, with additive therapeutic effects enabling the efficacy of lower drug doses and decreasing the associated toxicity. Understanding the mechanisms that underlie immunotherapy for CL provides critical insights into developing safer and more effective treatments for this neglected tropical disease. Identifying suitable therapeutic candidates and establishing their safety and efficacy are essential steps in this process. However, the feasibility and utility of these treatments in resource-limited settings must also be considered, taking into account factors such as cost of production, temperature stability, and overall patient access.

Application of CL Detect™ rapid test for diagnosis and liposomal amphotericin B for treatment of cutaneous leishmaniasis: A retrospective analysis from a tertiary care centre in a non-endemic area in India

Background Increasing urbanisation has led to the occurrence of cutaneous leishmaniasis (CL) in new areas, which was otherwise localised to endemic areas. Healthcare workers should be made aware of this entity to ensure clinical suspicion of CL and investigations needed to confirm CL. The article describes patients seen at a tertiary hospital in Delhi. Aims To establish the utility of the CL Detect Rapid test as a diagnostic tool and the efficacy of Liposomal Amphotericin B (LAmB) for the complete cure of CL patients. Methods Data of patients of CL (n = 16) was retrospectively analysed concerning diagnosis and treatment. Diagnosis rested on histopathology, real-time PCR, and CL Detect Rapid Test. Speciation of the parasite was based on the Internal transcribed spacer-I gene. Patients were treated with LAmB (i.v., 5 mg/kg up to three doses, five days apart). Results A positivity of 81.3% (95%CI, 54.4-96) was observed for CL Detect Rapid test in comparison with 100% (95%CI, 79.4-100.0) for real-time PCR and 43.8% (95%CI, 19.8-70.1) for microscopy/histopathological examination. L. tropica was the infective species in all cases. All the patients treated with LAmB responded to treatment, and 9/10 patients demonstrated complete regression of lesions, while one was lost to follow-up. Limitations It is a retrospective study, and the data includes only confirmed cases of CL at a single centre. Conclusion This study highlights the utility of CL Detect as a promising diagnostic tool and the efficacy of LAmB for the complete cure of CL.

Treatment options for leishmaniasis

Leishmaniasis is broadly classified into three types: cutaneous, mucocutaneous and visceral. The visceral form is most dangerous and can result in death. Although leishmaniasis is an ancient disease, its treatment is still challenging. Several drugs, differing in their cost, toxicity, treatment duration and emergence of drug resistance, are used for different types of leishmaniasis. To overcome these limitations, the search for newer drugs and other treatments continues. In this article, we discuss conventional drugs, other treatments, including newer options such as immunotherapy and immunochemotherapy, and future prospects for leishmaniasis treatment.

Comparison of Intralesional Meglumine Antimonite along with oral Itraconazole to Intralesional Meglumine Antimonite in the treatment of Cutaneous Leishmaniasis

BACKGROUND & OBJECTIVE

Cutaneous leishmaniasis (CL) is endemic in developing countries like Pakistan. Pentavalent antimonials are still drug of choice, despite being toxic and intolerable for patients. Second line treatments have been extensively studied but the results of their efficacy are conflicting. This, to our knowledge, will be the first study in this regard. Our objective was to determine if combination of oral itraconazole with intralesional (IL) meglumine antimoniate (MA) reduces the duration of treatment for cutaneous leishmaniasis, as compared to intralesional MA alone.

METHODS

A randomized controlled trial (single blinded) was carried out from August 2017 till December 2017 on 69 patients who fulfilled inclusion criteria. They were assigned to Group-A or B by lottery method. Group-A patients received IL MA once a week while Group-B received oral itraconazole 200mg, once daily, for six weeks along with similar regimen of IL MA as Group-A. The patients were assessed every three weeks by the blinded assessor till clinical cure was achieved. A follow up visit, two months after clinical cure was done to look for relapse of the disease.

RESULTS

Thirty patients in Group-A and 35 patients in Group-B completed the study. At 3, 6, 9 and 12 weeks the patients were assessed for: no, partial or complete response and results of the two groups were compared for statistical significance. The p-values of 0.20, 0.57 and 0.11 at 3, 6 and 9 weeks, respectively, depict that there was no significant difference at any step of assessment between the two groups in terms of healing. The p values of each t test was>0.05 refuting the hypothesis.

CONCLUSION

Combination of oral itraconazole with intralesional MA offered no benefit over intralesional MA alone in the management of cutaneous leishmaniasis in terms of duration of therapy.

Second Generation of Mannich Base-Type Derivatives with in Vivo Activity against Trypanosoma cruzi

Chagas disease is a potentially life-threatening and neglected tropical disease caused by Trypanosoma cruzi. One of the most important challenges related to Chagas disease is the search for new, safe, effective, and affordable drugs since the current therapeutic arsenal is inadequate and insufficient. Here, we report a simple and cost-effective synthesis and the biological evaluation of the second generation of Mannich base-type derivatives. Compounds 7, 9, and 10 showed improved in vitro efficiency and lower toxicity than benznidazole, in addition to no genotoxicity; thus, they were applied in in vivo assays to assess their activity in both acute and chronic phases of the disease. Compound 10 presented a similar profile to benznidazole from the parasitological perspective but also yielded encouraging data, as no toxicity was observed. Moreover, compound 9 showed lower parasitaemia and higher curative rates than benznidazole, also with lower toxicity in both acute and chronic phases. Therefore, further studies should be considered to optimize compound 9 to promote its further preclinical evaluation.

Efficacy of azole therapy for tegumentary leishmaniasis: A systematic review and meta-analysis

Background

Several controlled and uncontrolled studies addressing azole antifungal drugs for cutaneous and mucosal leishmaniasis have been published with inconclusive results. We conducted a systematic literature review of studies evaluating the efficacy and toxicity associated with azole therapy for tegumentary leishmaniasis.

Methodology

PRISMA guidelines for systematic reviews and the Cochrane manual were followed, and the review methodology was registered (PROSPERO; CRD42016048668). Sources included the EMBASE, Web of Science, MEDLINE, LILACS, and IBECS databases along with a manual search of references from evaluated studies. Additional resources such as Google Scholar and clinicaltrials.gov were also searched. We included all studies reporting cure rate after cutaneous or mucosal leishmaniasis treatment with systemic azole drugs, regardless of their design. R software was used to estimate global rates of success and adverse events with each drug. The main outcome of interest was clinical cure, defined as complete re-epithelialization of all lesions.

Results

A total of 37 studies involving 1259 patients that reported outcomes after fluconazole (9), ketoconazole (14) and itraconazole (15) treatments were included. Only 14 (38%) were randomized controlled trials (RCT). The pooled azole final efficacy rate was 64% (CI95%: 57–70%) for all studies and 60% (CI95%: 50–70%) (p = 0.41) if only RCTs studies were considered. Twenty-four studies were conducted in the Old World and 13 studies in the Americas. The final efficacy rate according to New and Old World were 62% (CI95%: 43–77%) and 66% (CI95%: 58–73%), respectively. The final efficacy rate of azoles according to species were 89% (CI95%: 50–98%) for L. mexicana; 88% for L. infantum (CI95%: 27–99%); 80% for L. donovani; 53% (CI95%: 29–76%) for L. major; 49% for L. braziliensis (CI95%: 21–78%); and 15% (CI95%: 1–84%) for L. tropica. The cure rates were similar among the fluconazole, ketoconazole and itraconazole group arms (p = 0.89), specifically 61% (CI95%: 48–72%), 64% (CI95%: 44–80%) 65% (CI95%: 56–72%), respectively. Adverse events during fluconazole, itraconazole and ketoconazole therapy were reported in 7% (CI95%: 3–14%), 12% (CI95% 8–19%) and 13% (CI95%: 6–29%) of treated patients, respectively, without difference among them (p = 0.35). This systematic review included studies with small samples and both non-comparative and non-randomized studies and the main limitation was the low quality of the available studies.

Conclusions

Available evidence suggests that fluconazole, ketoconazole and itraconazole have similar and modest efficacy rates for tegumentary leishmaniasis treatment. There is insufficient evidence to support the exclusive use of azole therapy as a single agent for leishmaniasis treatment.

Efficacy of cryotherapy for the treatment of cutaneous leishmaniasis: meta-analyses of clinical trials

BACKGROUND

Cryotherapy is a local treatment for cutaneous leishmaniasis with variable efficacy and greater safety than conventional treatment. The objective of this study is to evaluate the efficacy and safety of cryotherapy for the treatment of cutaneous leishmaniasis and to compare it with pentavalent antimonials.

METHODS

A meta-analysis based on a search of nine databases with eight strategies was conducted. Inclusion and exclusion criteria were applied, the methodological quality of each article was evaluated, and the reproducibility of the study selection and information extraction from each clinical trial was assured. The per lesion and per patient efficacy was calculated, and a meta-analysis of relative risks with the random effects model and the Dersimonian and Laird's, Begg, and Egger tests, along with a sensitivity analysis, were performed. A meta-regression based on the methodological quality of the trials included was also performed.

RESULTS

Eight studies were included in which respective per lesion efficacies of 67.3 % and 67.7 % were reported for cryotherapy and pentavalent antimonials. In 271 patients treated with cryotherapy and in 199 with pentavalent antimonials, respective per protocol and intent to treat efficacies of 63.6 % and 54.2 % were found in the first group, and per protocol and intent to treat efficacies of 74.7 % and 68.3 % were found in the second group. The relative risk for the comparison of efficacy in the two groups was 0.73 (0.42-1.29). The results of the sensitivity analysis and the meta-regression analysis of relative risks were statistically equal to the overall results.

CONCLUSION

This investigation provides evidence in favor of the use of cryotherapy given that its efficacy is similar to that of pentavalent antimonials.

Topical Treatment Modalities for Old World Cutaneous Leishmaniasis: A Review

Diagnosis and therapy of cutaneous leishmaniasis (CL) can be difficult due to the variability of the clinical pictures and resistance to therapy. There is no vaccine currently available for CL. The aim of the present review is to describe different topical treatment modalities for old world CL. The mainstays of treatment for old world CL are pentavalent antimony compounds which are administered parenterally or intralesionally. New topical treatment alternatives have been available within the past few years. Amongst several treatments used topically, physical therapies including cryotherapy, heat therapy and CO2 laser are promising for the treatment of old world CL. Along with that, other randomized placebo controlled trials should be designed to find new effective therapeutic regimens.

Therapeutic options and vaccine development in the treatment of leishmaniasis

Early treatment of leishmaniasis is critical to achieve cure, prevent psychological and social distress, and prevent transmission of disease. Untreated Leishmaniasis-cutaneous leishmaniasis, mucocutaneous leishmaniasis and visceral leishmaniasis - results in disfiguring scars and high rates of morbidity and mortality in highly endemic regions of the world. However, cure rates with available therapeutics are limited due to cost, therapeutic toxicity and the growing rate of resistance. New therapeutic targets for medications and vaccine development are under investigation to provide improved healing and efficacy for the treatment of Leishmania spp.

Topical resiquimod protects against visceral infection with Leishmania infantum chagasi in mice

New prevention and treatment strategies are needed for visceral leishmaniasis, particularly ones that can be deployed simply and inexpensively in areas where leishmaniasis is endemic. Synthetic molecules that activate Toll-like receptor 7 and 8 (TLR7/8) pathways have previously been demonstrated to enhance protection against cutaneous leishmaniasis. We initially sought to determine whether the TLR7/8-activating molecule resiquimod might serve as an effective vaccine adjuvant targeting visceral leishmaniasis caused by infection with Leishmania infantum chagasi. Resiquimod was topically applied to the skin of mice either prior to or after systemic infection with L. infantum chagasi, and parasite burdens were assessed. Surprisingly, topical resiquimod application alone, in the absence of vaccination, conferred robust resistance to mice against future intravenous challenge with virulent L. infantum chagasi. This protection against L. infantum chagasi infection persisted as long as 8 weeks after the final topical resiquimod treatment. In addition, in mice with existing infections, therapeutic treatment with topical resiquimod led to significantly lower visceral parasite loads. Resiquimod increased trafficking of leukocytes, including B cells, CD4(+) and CD8(+) T cells, dendritic cells, macrophages, and granulocytes, in livers and spleens, which are the key target organs of visceralizing infection. We conclude that topical resiquimod leads to systemic immune modulation and confers durable protection against visceralizing L. infantum chagasi infection, in both prophylactic and therapeutic settings. These studies support continued studies of TLR-modulating agents to determine mechanisms of protection and also provide a rationale for translational development of a critically needed, novel class of topical, preventative, and therapeutic agents for these lethal infections.

Drug delivery systems for the topical treatment of cutaneous leishmaniasis

INTRODUCTION

The parenteral administration of pentavalent antimonials for the treatment of all forms of leishmaniasis, including cutaneous leishamniasis (CL), has several limitations. Therapy is long, requiring repeated doses and the adverse reactions are frequent. Topical treatment is an attractive alternative for CL, offering significant advantages over systemic therapy: fewer adverse effects, ease of administration, and lower costs.

AREAS COVERED

This review covers, from 1984 to the present, the progress achieved for the development of topical treatment for CL, using different drugs such as paromomycin (PA), imiquimod, amphotericin B (AmB), miltefosine, and buparvaquone. PA is the most commonly studied drug, followed by AmB and Imiquimod. These drugs were incorporated in conventional dosage forms or loaded in lipid nanocarries, which have been used mainly for improved skin delivery and antileishmanial activity.

EXPERT OPINION

Developing an effective topical treatment for CL using these antileishmanial drugs still remains a great challenge. Insights into the most promising delivery strategies to improve treatment of CL with PA and AmB using conventional dosage forms, lipid nanocarriers, and combined therapy are presented and discussed. The results obtained with combined therapy and alternative delivery systems are promising perspectives for improving topical treatment of CL.

Molecular factors governing inhibition of arylimidamides against Leishmania: conservative computational modeling to improve chemotherapies

A dataset of 55 compounds with inhibitory activity against Leishmania donovani axenic amastigotes and Leishmania amazonensis intracellular parasites was examined through three-dimensional quantitative structure-activity relationship modeling employing molecular descriptors from both rigid and flexible compound alignments. For training and testing purposes, the compounds were divided into two datasets of 45 and 10 compounds, respectively. Statistically significant models were constructed and validated via the internal and external predictions. For all models employing steric, electrostatic, hydrophobic, H-donor and H-acceptor molecular descriptors, the R² values were greater than 0.90 and the SEE values were less than 0.22. The models obtained from rigid and flexible compounds were employed together to obtain a conservative method for predictions. This method minimized under predictions. Molecular descriptors from the models were then extrapolated, for the overall predictive devices and the individual compounds, and examined with regard to inhibitory activity. Information gained from the molecular descriptors is useful in the design of novel compounds. The models obtained can be employed to predict activities of the compounds designed and/or form predictions for compounds that exist and have not yet been examined with biological inhibitory assays.