Pharmacotherapy for Leishmaniasis in the United States: Focus on Miltefosine

Discovery of pyrazolopyrrolidinones as potent, broad-spectrum inhibitors of Leishmania infection

Introduction

Leishmaniasis is a parasitic disease that affects more than 1 million people worldwide annually, predominantly in resource-limited settings. The challenge in compound development is to exhibit potent activity against the intracellular stage of the parasite (the stage present in the mammalian host) without harming the infected host cells. We have identified a compound series (pyrazolopyrrolidinones) active against the intracellular parasites of Leishmania donovani and L. major; the causative agents of visceral and cutaneous leishmaniasis in the Old World, respectively.

Methods

In this study, we performed medicinal chemistry on a newly discovered antileishmanial chemotype, with over 100 analogs tested. Studies included assessments of antileishmanial potency, toxicity towards host cells, and in vitro ADME screening of key drug properties.

Results and discussion

Members of the series showed high potency against the deadliest form, visceral leishmaniasis (approximate EC₅₀ ≥ 0.01 μM without harming the host macrophage up to 10.0 μM). In comparison, the most efficient monotherapy treatment for visceral leishmaniasis is amphotericin B, which presents similar activity in the same assay (EC₅₀ = 0.2 μM) while being cytotoxic to the host cell at 5.0 μM. Continued development of this compound series with the Discovery Partnership with Academia (DPAc) program at the GlaxoSmithKline Diseases of the Developing World (GSK DDW) laboratories found that the compounds passed all of GSK's criteria to be defined as a potential lead drug series for leishmaniasis.

Conclusion

Here, we describe preliminary structure-activity relationships for antileishmanial pyrazolopyrrolidinones, and our progress towards the identification of candidates for future in vivo assays in models of visceral and cutaneous leishmaniasis.

A decade of approved first-in-class small molecule orphan drugs: Achievements, challenges and perspectives

In the past decade (2011-2020), there was a growing interest in the discovery and development of orphan drugs for the treatment of rare diseases. However, rare diseases only account for a population of 0.65‰-1‰ which usually occur with previously unknown biological mechanisms and lack of specific therapeutics, thus to increase the demands for the first-in-class (FIC) drugs with new biological targets or mechanisms. Considering the achievements in the past 10 years, a total of 410 drugs were approved by U.S. Food and Drug Administration (FDA), which contained 151 FIC drugs and 184 orphan drugs, contributing to make up significant numbers of the approvals. Notably, more than 50% of FIC drugs are developed as orphan drugs and some of them have already been milestones in drug development. In this review, we aim to discuss the FIC small molecules for the development of orphan drugs case by case and highlight the R&D strategy with novel targets and scientific breakthroughs.

Single-Cell Mass Spectrometry Enables Insight into Heterogeneity in Infectious Disease

Cellular heterogeneity is generally overlooked in infectious diseases. In this study, we investigated host cell heterogeneity during infection with Trypanosoma cruzi (T. cruzi) parasites, causative agents of Chagas disease (CD). In chronic-stage CD, only a few host cells are infected with a large load of parasites and symptoms may appear at sites distal to parasite colonization. Furthermore, recent work has revealed T. cruzi heterogeneity with regard to replication rates and drug susceptibility. However, the role of cellular-level metabolic heterogeneity in these processes has yet to be assessed. To fill this knowledge gap, we developed a Single-probe SCMS (single-cell mass spectrometry) method compatible with biosafety protocols, to acquire metabolomics data from individual cells during T. cruzi infection. This study revealed heterogeneity in the metabolic response of the host cells to T. cruzi infection in vitro. Our results showed that parasite-infected cells possessed divergent metabolism compared to control cells. Strikingly, some uninfected cells adjacent to infected cells showed metabolic impacts as well. Specific metabolic changes include increases in glycerophospholipids with infection. These results provide novel insight into the pathogenesis of CD. Furthermore, they represent the first application of bioanalytical SCMS to the study of mammalian-infectious agents, with the potential for broad applications to study infectious diseases.

Assessment of serum amylase, lipase and associated factors among patients with visceral leishmaniasis treated with sodium stibogluconate/paromomycin at University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia

BACKGROUND

Visceral leishmaniasis (VL) is a life-threatening parasitic disease next to malaria, which is responsible for the death of 50,000 patients annually. It has three major clinical stages, including visceral, cutaneous, and mucocutaneous leishmaniasis. Ethiopia is one of the east African countries commonly affected with leishmanisis disease. There are many drugs for leishmaniasis, including sodium stibogluconate and paromomycin combined therapy. However, the adverse effect of those combined drugs is not well-defined. Therefore, the purpose of this study was to assess serum amylase, lipase, and associated factors among patients with VL treatment with those combined drugs.

METHODS

Hospital-based cross-sectional study was conducted at the University of Gondar Comprehensive Specialized Hospital Leishmaniasis Research and Treatment Center from February to September 2020 G.C. Simple random sampling technique was utilized to select study participants. The study participants who fulfill the inclusion criteria were included in the study with written informed consent. 5 ml of blood was withdrawn by an experienced health professional to analyze serum amylase and lipase level. Descriptive data was presented by tables, charts and graphs. Data was cleared, entered by Epi-data version 3.1 then transfer to STATA 14.1 SE version and for analysis paired t-test was used, for factors correlation and regression was used. Those factor variable who have p-value <0.25 was filtered and goes to multivariate regression and p-value <0.05 was considered as significant variables.

RESULTS

The result of this study showed that there was a significant mean difference between serum pancreatic amylase and lipase before and after treatment. The mean ± SD level of serum amylase after treatment showed a statistically significant elevation (P<0.001) as compared to its level before treatment. Similarly, the mean ± SD level of serum lipase after treatment showed a statistically significant elevation (P<0.001) as compared to its level before treatment. There was also significant association between age and baseline serum amylase as compared to serum amylase after treatment. Similarly, there was also significant relation of age and serum lipase with serum lipase after treatment.

CONCLUSION

In this study, the level of serum amylase and lipase at treatment of cure was higher and there was an increase in mean serum amylase and lipase after a patient taking sodium stibogluconate and paromomycin combined drugs. Consequently, the elevated result of these biochemical profiles mainly associated with drug induced adverse effect and associated risk factors in VL patients.

Leishmanicidal therapy targeted to parasite proteases

Leishmaniasis is considered a serious public health problem and the current available therapy has several disadvantages, which makes the search for new therapeutic targets and alternative treatments extremely necessary. In this context, this review focuses on the importance of parasite proteases as target drugs against Leishmania parasites, as a chemotherapy approach. Initially, we discuss about the current scenario for the treatment of leishmaniasis, highlighting the main drugs used and the problems related to their use. Subsequently, we describe the inhibitors of major proteases of Leishmania already discovered, such as Compound s9 (aziridine-2,3-dicarboxylate), Compound 1c (benzophenone derivative), Au2Phen (gold complex), AubipyC (gold complex), MDL 28170 (dipeptidyl aldehyde), K11777, Hirudin, diazo-acetyl norleucine methyl ester, Nelfinavir, Saquinavir, Nelfinavir, Saquinavir, Indinavir, Saquinavir, GNF5343 (azabenzoxazole), GNF6702 (azabenzoxazole), Benzamidine and TPCK. Next, we discuss the importance of the protease gene to parasite survival and the aspects of the validation of proteases as target drugs, with emphasis on gene disruption. Then, we describe novel important strategies that can be used to support the research of new antiparasitic drugs, such as molecular modeling and nanotechnology, whose main targets are parasitic proteases. And finally, we discuss possible perspectives to improve drug development. Based on all findings, proteases could be considered potential targets against leishmaniasis.

Efficacy of Apigenin and Miltefosine Combination Therapy against Experimental Cutaneous Leishmaniasis

Leishmaniasis is a neglected tropical disease caused by several different species of Leishmania. Treatment of leishmaniasis involves a limited drug arsenal that is associated with severe side effects, high costs, and drug resistance. Therefore, combination therapy has emerged as a strategy to improve leishmaniasis treatment. Here, we report the interaction of miltefosine and apigenin in vitro and in vivo. Combination therapy using low doses of these two drugs results in good clinical and parasitological responses.

In vitro activity of new N-benzyl-1H-benzimidazol-2-amine derivatives against cutaneous, mucocutaneous and visceral Leishmania species

The identification of specific therapeutic targets and the development of new drugs against leishmaniasis are urgently needed, since chemotherapy currently available for its treatment has several problems including many adverse side effects. In an effort to develop new antileishmanial drugs, in the present study a series of 28 N-benzyl-1H-benzimidazol-2-amine derivatives was synthesized and evaluated in vitro against Leishmania mexicana promastigotes. Compounds 7 and 8 with the highest antileishmanial activity (micromolar) and lower cytotoxicity than miltefosine and amphotericin B were selected to evaluate their activity against L. braziliensis 9and L. donovani, species causative of mucocutaneous and visceral leishmaniasis, respectively. Compound 7 showed significantly higher activity against L. braziliensis promastigotes than compound 8 and slightly lower than miltefosine. Compounds 7 and 8 had IC₅₀ values in the micromolar range against the amastigote of L. mexicana and L. braziliensis. However, both compounds did not show better activity against L. donovani than miltefosine. Compound 8 showed the highest SI against both parasite stages of L. mexicana. In addition, compound 8 inhibited 68.27% the activity of recombinant L. mexicana arginase (LmARG), a therapeutic target for the treatment of leishmaniasis. Docking studies were also performed in order to establish the possible mechanism of action by which this compound exerts its inhibitory effect. Compound 8 shows promising potential for the development of more potent antileishmanial benzimidazole derivatives.

Emerging infectious diseases with cutaneous manifestations: Fungal, helminthic, protozoan and ectoparasitic infections

Given increased international travel, immigration, changing climate conditions, and the increased incidence of iatrogenic immunosuppression, fungal, protozoan, helminthic, and ectoparasitic infections that were once uncommon are being seeing more frequently in the Western hemisphere. However, the diagnosis and management of these infections is fraught with a lack of consistency because there is a dearth of dermatology literature on the cutaneous manifestations of these infections. In addition, delays in the diagnosis and treatment of these diseases can lead to significant patient morbidity and mortality. We review the epidemiology, cutaneous manifestations, diagnostic modalities, and treatment options for emerging fungal, protozoan, helminthic, and ectoparasitic infections. It should be noted, however, that throughout this review we cite statistics documenting their increased incidence to back-up these infections as emerging, and although some of the diagnoses are clinical, others rely on newer laboratory tests, and the possibility exists that the increased incidence could be caused by better detection methods.

LC-coupled ESI MS for quantification of miltefosine in human and hamster plasma

Background: Leishmaniasis, a fatal parasitic disease, is the second largest parasitic killer in the world and miltefosine is the first and only oral drug available for its treatment. Results: A rapid, sensitive and simple LC–MS/MS method for miltefosine quantification in hamster and human plasma was developed and validated over the range of 2.5–400 ng/ml. The mass spectrometric detection of the drug was carried out in multiple reaction monitoring mode (m/z 408.1→125.1) using an electrospray positive ionization. The protein precipitation method was employed for sample (50 µl) cleanup. Conclusion: The proposed method provided accurate and precise high-throughput quantification of miltefosine in plasma and was successfully applied to its oral PK study in Golden Syrian hamsters.