bay-44-4400 and Onchocerciasis

Current mass drug administration (MDA) programs for the treatment of human river blindness (onchocerciasis) caused by the filarial worm Onchocerca volvulus rely on ivermectin, an anthelmintic originally developed for animal health. These treatments are primarily directed against migrating microfilariae and also suppress fecundity for several months, but fail to eliminate adult O. volvulus. Therefore, elimination programs need time frames of decades, well exceeding the life span of adult worms. The situation is worsened by decreased ivermectin efficacy after long-term therapy. To improve treatment options against onchocerciasis, a drug development candidate should ideally kill or irreversibly sterilize adult worms. Emodepside is a broad-spectrum anthelmintic used for the treatment of parasitic nematodes in cats and dogs (Profender and Procox). Our current knowledge of the pharmacology of emodepside is the result of more than 2 decades of intensive collaborative research between academia and the pharmaceutical industry. Emodepside has a novel mode of action with a broad spectrum of activity, including against extraintestinal nematode stages such as migrating larvae or macrofilariae. Therefore, emodepside is considered to be among the most promising candidates for evaluation as an adulticide treatment against onchocerciasis. Consequently, in 2014, Bayer and the Drugs for Neglected Diseases initiative (DNDi) started a collaboration to develop emodepside for the treatment of patients suffering from the disease. Macrofilaricidal activity has been demonstrated in various models, including Onchocerca ochengi in cattle, the parasite most closely related to O. volvulus. Emodepside has now successfully passed Phase I clinical trials, and a Phase II study is planned. This Bayer-DNDi partnership is an outstanding example of "One World Health," in which experience gained in veterinary science and drug development is translated to human health and leads to improved tools to combat neglected tropical diseases (NTDs) and shorten development pathways and timelines in an otherwise neglected area.

Topics: Antiparasitic Agents; Depsipeptides; Drug Development; Humans; Onchocerciasis

Emodepside is an anthelmintic, originally developed for veterinary use. We investigated in healthy subjects the safety, and pharmacokinetics of a liquid service formulation (LSF) and immediate release (IR) tablet of emodepside in 2 randomised, parallel-group, placebo-controlled, Phase I studies.. Seventy-nine subjects in 10 cohorts in the single ascending dose study and 24 subjects in 3 ascending-dose cohorts in the multiple ascending dose study were enrolled. Emodepside as LSF was administered orally as single 1-40-mg doses and for 10 days as 5 or 10 mg once daily and 10-mg twice daily doses, respectively. Pharmacokinetics and safety were assessed up to 21 and 30 days, respectively. In addition, IR tablets containing 5 or 20 mg emodepside were tested in the single ascending dose study.. Emodepside as LSF was rapidly absorbed under fasting conditions, with dose-proportional increase in plasma concentrations at doses from 1 to 40 mg. Terminal half-life was > 500 hours. In the fed state, emodepside was absorbed more slowly but overall plasma exposure was not significantly affected. Compared to the LSF, the rate and extent of absorption was significantly lower with the tablets.. Overall, emodepside had acceptable safety and tolerability profiles, no major safety concerns, after single oral administration of 20 mg as LSF and after multiple oral administration over 10 days at 5 and 10 mg OD and at 10 mg twice daily. For further clinical trials, the development of a tablet formulation overcoming the limitations observed in the present study with the IR tablet formulation is considered.

Topics: Administration, Oral; Area Under Curve; Depsipeptides; Dose-Response Relationship, Drug; Food-Drug Interactions; Half-Life; Healthy Volunteers; Humans; Male; Onchocerciasis; Onchocerciasis, Ocular

To accelerate the progress towards onchocerciasis elimination, a macrofilaricidal drug that kills the adult parasite is urgently needed. Emodepside has shown macrofilaricidal activity against a variety of nematodes and is currently under clinical development for the treatment of onchocerciasis. The aims of this study were i) to characterize the population pharmacokinetic properties of emodepside, ii) to link its exposure to adverse events in healthy volunteers, and iii) to propose an optimized dosing regimen for a planned phase II study in onchocerciasis patients.. Plasma concentration-time profiles and adverse event data were obtained from 142 subjects enrolled in three phase I studies, including a single-dose, and a multiple-dose, dose-escalation study as well as a relative bioavailability study. Nonlinear mixed-effects modeling was used to evaluate the population pharmacokinetic properties of emodepside. Logistic regression modeling was used to link exposure to drug-related treatment-emergent adverse events (TEAEs). Emodepside pharmacokinetics were well described by a transit-absorption model, followed by a 3-compartment disposition model. Body weight was included as an allometric function and both food and formulation had a significant impact on absorption rate and relative bioavailability. All drug-related TEAEs were transient, and mild or moderate in severity. An increase in peak plasma concentration was associated with an increase in the odds of experiencing a drug-related TEAE of interest.. Pharmacokinetic modeling and simulation was used to derive an optimized, body weight-based dosing regimen, which allows for achievement of extended emodepside exposures above target concentrations while maintaining acceptable tolerability margins.

Topics: Adult; Body Weight; Depsipeptides; Drug Development; Humans; Onchocerciasis

Several issues have been identified with the current programs for the elimination of onchocerciasis that target only transmission by using mass drug administration (MDA) of the drug ivermectin. Alternative and/or complementary treatment regimens as part of a more comprehensive strategy to eliminate onchocerciasis are needed. We posit that the addition of "prophylactic" drugs or therapeutic drugs that can be utilized in a prophylactic strategy to the toolbox of present microfilaricidal drugs and/or future macrofilaricidal treatment regimens will not only improve the chances of meeting the elimination goals but may hasten the time to elimination and also will support achieving a sustained elimination of onchocerciasis. These "prophylactic" drugs will target the infective third- (L3) and fourth-stage (L4) larvae of Onchocerca volvulus and consequently prevent the establishment of new infections not only in uninfected individuals but also in already infected individuals and thus reduce the overall adult worm burden and transmission. Importantly, an effective prophylactic treatment regimen can utilize drugs that are already part of the onchocerciasis elimination program (ivermectin), those being considered for MDA (moxidectin), and/or the potential macrofilaricidal drugs (oxfendazole and emodepside) currently under clinical development. Prophylaxis of onchocerciasis is not a new concept. We present new data showing that these drugs can inhibit L3 molting and/or inhibit motility of L4 at IC50 and IC90 that are covered by the concentration of these drugs in plasma based on the corresponding pharmacological profiles obtained in human clinical trials when these drugs were tested using various doses for the therapeutic treatments of various helminth infections.

Topics: Animals; Benzimidazoles; Depsipeptides; Filaricides; Humans; Ivermectin; Larva; Leukocytes, Mononuclear; Macrolides; Onchocerca volvulus; Onchocerciasis

Onchocerciasis (river blindness), caused by the filarial worm Onchocerca volvulus, is a neglected tropical disease mostly affecting sub-Saharan Africa and is responsible for >1.3 million years lived with disability. Current control relies almost entirely on ivermectin, which suppresses symptoms caused by the first-stage larvae (microfilariae) but does not kill the long-lived adults. Here, we evaluated emodepside, a semi-synthetic cyclooctadepsipeptide registered for deworming applications in companion animals, for activity against adult filariae (i.e., as a macrofilaricide). We demonstrate the equivalence of emodepside activity on SLO-1 potassium channels in Onchocerca volvulus and Onchocerca ochengi, its sister species from cattle. Evaluation of emodepside in cattle as single or 7-day treatments at two doses (0.15 and 0.75 mg/kg) revealed rapid activity against microfilariae, prolonged suppression of female worm fecundity, and macrofilaricidal effects by 18 months post treatment. The drug was well tolerated, causing only transiently increased blood glucose. Female adult worms were mostly paralyzed; however, some retained metabolic activity even in the multiple high-dose group. These data support ongoing clinical development of emodepside to treat river blindness.

Topics: Animals; Cattle; Cattle Diseases; Depsipeptides; Filaricides; Large-Conductance Calcium-Activated Potassium Channels; Onchocerca; Onchocerciasis