BACKGROUND-KAE609 (cipargamin; formerly NITD609, Novartis Institute for Tropical Diseases) is a new synthetic antimalarial spiroindolone analogue with potent, dose-dependent antimalarial activity against asexual and sexual stages of Plasmodium falciparum.
Diarrheal disease is responsible for 8.6% of global child mortality. Recent epidemiological studies found the protozoan parasite Cryptosporidium to be a leading cause of pediatric diarrhea with particularly grave impact on infants and immunocompromised individuals. There is neither a vaccine nor effective treatment. We establish a drug discovery process built on scalable phenotypic assays and mouse models that takes advantage of transgenic parasites. Screening a library of compounds with anti-parasitic activity we identified pyrazolopyridines as inhibitors of Cryptosporidium parvum and C. hominis. Oral treatment with the pyrazolopyridine KDU731 results in potent reduction in intestinal infection of immunocompromised mice. Treatment also leads to rapid resolution of diarrhea and dehydration in neonatal calves, a clinical model of cryptosporidiosis that closely resembles human infection. Our results suggest the Cryptosporidium lipid kinase PI(4)K as a target for pyrazolopyridines and warrant further preclinical evaluation of KDU731 as a drug candidate for the treatment of cryptosporidiosis.
Background KAF156 belongs to a new class of antimalarial agents (imidazolopiperazines), with activity against asexual and sexual blood stages and the preerythrocytic liver stages of malarial parasites. Methods We conducted a phase 2, open-label, two-part study at five centers in Thailand and Vietnam to assess the antimalarial efficacy, safety, and pharmacokinetic profile of KAF156 in adults with acute Plasmodium vivax or P. falciparum malaria. Assessment of parasite clearance rates in cohorts of patients with vivax or falciparum malaria who were treated with multiple doses (400 mg once daily for 3 days) was followed by assessment of the cure rate at 28 days in a separate cohort of patients with falciparum malaria who received a single dose (800 mg). Results Median parasite clearance times were 45 hours (interquartile range, 42 to 48) in 10 patients with falciparum malaria and 24 hours (interquartile range, 20 to 30) in 10 patients with vivax malaria after treatment with the multiple-dose regimen and 49 hours (interquartile range, 42 to 54) in 21 patients with falciparum malaria after treatment with the single dose. Among the 21 patients who received the single dose and were followed for 28 days, 1 had reinfection and 7 had recrudescent infections (cure rate, 67%; 95% credible interval, 46 to 84). The mean (±SD) KAF156 terminal elimination half-life was 44.1±8.9 hours. There were no serious adverse events in this small study. The most common adverse events included sinus bradycardia, thrombocytopenia, hypokalemia, anemia, and hyperbilirubinemia. Vomiting of grade 2 or higher occurred in 2 patients, 1 of whom discontinued treatment because of repeated vomiting after receiving the single 800-mg dose. More adverse events were reported in the single-dose cohort, which had longer follow-up, than in the multiple-dose cohorts. Conclusions KAF156 showed antimalarial activity without evident safety concerns in a small number of adults with uncomplicated P. vivax or P. falciparum malaria. (Funded by Novartis and others; ClinicalTrials.gov number, NCT01753323.)
KAF156 belongs to a new class of antimalarial, the imidazolopiperazines, and is currently in clinical development for the treatment of uncomplicated malaria. This first-in-human, single- and multiple-ascending-dose study in 70 healthy male volunteers determined the maximum oral dose of KAF156 tolerated by healthy adults and derived pharmacokinetic data (including preliminary food effect) to enable dose calculations for malaria patients. KAF156 was studied in single-dose cohorts (10 to 1,200 mg, including one 400-mg food effect cohort (4 to 10 subjects/cohort), and in multiple-dose cohorts (60 to 600 mg once daily for 3 days; 8 subjects/cohort). The follow-up period was 6 to 14 days after the last dose. KAF156 was tolerated, with self-limited mild to moderate gastrointestinal and neurological adverse events. In treated subjects after single doses, headache (n = 4; 11.1%), diarrhea (n = 3; 8.3%), dizziness (n = 3; 8.3%), and abdominal pain (n = 2; 5.6%) were the most common adverse events. Headache (n = 4; 16.7%), nausea (n = 3; 12.5%), upper respiratory tract infection (n = 3; 12.5%), and dizziness (n = 2; 8.3%) were the most common adverse events following multiple doses. KAF156 time to maximum concentration (Tmax) was between 1.0 and 6.0 h. Both the area under the concentration-time curve (AUC) and maximum concentration (Cmax) increased more than dose-proportionally in both single- and multiple-ascending-dose cohorts (terminal half-life, 42.5 to 70.7 h). There was no significant accumulation over 3-day repeated administration. The extent of absorption was not significantly affected by food at a single dose of 400 mg, while mean Cmax decreased from 778 ng/ml to 627 ng/ml and Tmax was delayed from a median of 3.0 h under fasting conditions to 6.0 h under fed conditions. Renal elimination is a minor route.
The apicomplexan parasite Cryptosporidium is the second most important diarrheal pathogen causing life-threatening diarrhea in children, which is also associated with long-term growth faltering and cognitive deficiency. Cryptosporidiosis is a parasitic disease of public health concern caused by Cryptosporidium parvum and Cryptosporidium hominis. Currently, nitazoxanide is the only approved treatment for cryptosporidium infections. Unfortunately, it has limited efficacy in the most vulnerable patients, thus there is an urgent need for a safe and efficacious cryptosporidiosis drug. In this work, we present our current perspectives on the target product profile for novel cryptosporidiosis therapies and the perceived challenges and possible mitigation plans at different stages in the cryptosporidiosis drug discovery process.
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