FDA Approves Benznidazole, First US Drug for Chagas Disease

Megan Brooks

August 29, 2017

The US Food and Drug Administration (FDA) has granted accelerated approval to benznidazole (Chemo Research, SL) for treatment of children aged 2 to 12 years with Chagas disease, becoming the first treatment approved in the United States for this rare disease.

Chagas disease, or American trypanosomiasis, is a parasitic infection caused by Trypanosoma cruzi. It can be transmitted through different routes, including contact with the feces of a certain insect, blood transfusions, or from a mother to her child during pregnancy.

Chagas disease primarily affects people living in rural parts of Latin America, but recent estimates suggest that there may be roughly 300,000 people in the United States with Chagas disease, the FDA said in a news release.

"The FDA is committed to making available safe and effective therapeutic options to treat tropical diseases," Edward Cox, MD, director of the Office of Antimicrobial Products in the FDA's Center for Drug Evaluation and Research, said in the release.

The safety and efficacy of benznidazole were demonstrated in two placebo-controlled clinical trials in children aged 6 to 12 years. In the first trial, about 60% of children treated with benznidazole had an antibody test change from positive to negative compared with about 14% of children who received a placebo.

Results in the second trial were similar, with about 55% of children treated with benznidazole having an antibody test change from positive to negative compared with 5% who received a placebo. An additional study of the safety and pharmacokinetics of benznidazole in children aged 2 to 12 years supports the dosing recommendations down to 2 years of age, the FDA said.

The most common adverse reactions to benznidazole were stomach pain, rash, decreased weight, headache, nausea, vomiting, abnormal white blood cell count, urticaria, pruritus, and decreased appetite. Benznidazole is associated with serious risks including serious skin reactions, nervous system effects, and bone marrow depression. Based on findings from animal studies, benznidazole could cause fetal harm when administered to pregnant women, the FDA cautions.

Benznidazole was approved through the FDA's accelerated approval pathway, which allows the agency to approve drugs for serious conditions where there is unmet medical need and adequate and well-controlled trials establish that the drug has an effect on a surrogate endpoint that is reasonably likely to predict a clinical benefit to patients. Further study is needed to verify and describe the anticipated clinical benefit of benznidazole, the FDA said.

Benznidazole had orphan drug status and underwent priority review. These designations were granted because Chagas disease is a rare disease and, until now, there were no approved drugs for Chagas disease in the United States.

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