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Discovery of novel hit compounds with broad activity against visceral and cutaneous Leishmania species by comparative phenotypic screening.

ABSTRACT: The limited success of recent phenotypic anti-leishmanial drug screening campaigns calls for new screening strategies for the discovery of clinically relevant hits. Here we present such a novel strategy based on physiologically relevant, ex vivo biology. We established high content phenotypic assays that combine primary murine macrophages and lesion-derived, virulent L. donovani and L. amazonensis amastigotes, which we applied to validate previously identified, anti-leishmanial hit compounds referred to as 'GSK Leish-Box'. Together with secondary screens using cultured promastigotes, our pipeline distinguished stage- and/or species-specific compounds, including 20 hits with broad activity at 10?µM against intracellular amastigotes of both viscerotropic and dermotropic Leishmania. Even though the GSK Leish-Box hits were identified by phenotypic screening using THP-1 macrophage-like cells hosting culture-derived L. donovani LdBob parasites, our ex vivo assays only validated anti-leishmanial activity at 10?µM on intra-macrophagic L. donovani for 23 out of the 188 GSK Leish-Box hits. In conclusion, our comparative approach allowed the identification of hits with broad anti-leishmanial activity that represent interesting novel candidates to be tested in animal models. Physiologically more relevant screening approaches such as described here may reduce the very high attrition rate observed during pre-clinical and clinical phases of the drug development process.

SUBMITTER: Lamotte S

PROVIDER: S-EPMC6345745 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Discovery of novel hit compounds with broad activity against visceral and cutaneous Leishmania species by comparative phenotypic screening.

Lamotte S S Aulner N N Späth G F GF Prina E E

Scientific reports 20190124 1

The limited success of recent phenotypic anti-leishmanial drug screening campaigns calls for new screening strategies for the discovery of clinically relevant hits. Here we present such a novel strategy based on physiologically relevant, ex vivo biology. We established high content phenotypic assays that combine primary murine macrophages and lesion-derived, virulent L. donovani and L. amazonensis amastigotes, which we applied to validate previously identified, anti-leishmanial hit compounds ref ...[more]

PMID: 30679614

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Project description:BACKGROUND:Praziquantel (PZQ) is the only widely available drug to treat schistosomiasis. Given the potential for drug resistance, it is prudent to search for novel therapeutics. Identification of anti-schistosomal chemicals has traditionally relied on phenotypic (whole organism) screening with adult worms in vitro and/or animal models of disease-tools that limit automation and throughput with modern microtiter plate-formatted compound libraries. METHODS:A partially automated, three-component phenotypic screen workflow is presented that utilizes at its apex the schistosomular stage of the parasite adapted to a 96-well plate format with a throughput of 640 compounds per month. Hits that arise are subsequently screened in vitro against adult parasites and finally for efficacy in a murine model of disease. Two GO/NO GO criteria filters in the workflow prioritize hit compounds for tests in the animal disease model in accordance with a target drug profile that demands short-course oral therapy. The screen workflow was inaugurated with 2,160 chemically diverse natural and synthetic compounds, of which 821 are drugs already approved for human use. This affords a unique starting point to 'reposition' (re-profile) drugs as anti-schistosomals with potential savings in development timelines and costs. FINDINGS:Multiple and dynamic phenotypes could be categorized for schistosomula and adults in vitro, and a diverse set of 'hit' drugs and chemistries were identified, including anti-schistosomals, anthelmintics, antibiotics, and neuromodulators. Of those hits prioritized for tests in the animal disease model, a number of leads were identified, one of which compares reasonably well with PZQ in significantly decreasing worm and egg burdens, and disease-associated pathology. Data arising from the three components of the screen are posted online as a community resource. CONCLUSIONS:To accelerate the identification of novel anti-schistosomals, we have developed a partially automated screen workflow that interfaces schistosomula with microtiter plate-formatted compound libraries. The workflow has identified various compounds and drugs as hits in vitro and leads, with the prescribed oral efficacy, in vivo. Efforts to improve throughput, automation, and rigor of the screening workflow are ongoing.

Project description:Leishmaniasis is a parasitic infection that afflicts approximately 12 million people worldwide. There are several limitations to the approved drug therapies for leishmaniasis, including moderate to severe toxicity, growing drug resistance, and the need for extended dosing. Moreover, miltefosine is currently the only orally available drug therapy for this infection. We addressed the pressing need for new therapies by pursuing a two-step phenotypic screen to discover novel, potent, and orally bioavailable antileishmanials. First, we conducted a high-throughput screen (HTS) of roughly 600,000 small molecules for growth inhibition against the promastigote form of the parasite life cycle using the nucleic acid binding dye SYBR Green I. This screen identified approximately 2,700 compounds that inhibited growth by over 65% at a single point concentration of 10 ?M. We next used this 2700 compound focused library to identify compounds that were highly potent against the disease-causing intra-macrophage amastigote form and exhibited limited toxicity toward the host macrophages. This two-step screening strategy uncovered nine unique chemical scaffolds within our collection, including two previously described antileishmanials. We further profiled two of the novel compounds for in vitro absorption, distribution, metabolism, excretion, and in vivo pharmacokinetics. Both compounds proved orally bioavailable, affording plasma exposures above the half-maximal effective concentration (EC50) concentration for at least 12 hours. Both compounds were efficacious when administered orally in a murine model of cutaneous leishmaniasis. One of the two compounds exerted potent activity against trypanosomes, which are kinetoplastid parasites related to Leishmania species. Therefore, this compound could help control multiple parasitic diseases. The promising pharmacokinetic profile and significant in vivo efficacy observed from our HTS hits highlight the utility of our two-step phenotypic screening strategy and strongly suggest that medicinal chemistry optimization of these newly identified scaffolds will lead to promising candidates for an orally available anti-parasitic drug.

Dataset Information

Discovery of novel hit compounds with broad activity against visceral and cutaneous Leishmania species by comparative phenotypic screening.

Publications

Discovery of novel hit compounds with broad activity against visceral and cutaneous Leishmania species by comparative phenotypic screening.

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