Researchers uncover how malaria parasite becomes resistant to fosmidomycin drug

Researchers have uncovered a way the malaria parasite becomes resistant to an investigational drug. The discovery, at Washington University School of Medicine in St. Louis, also is relevant for other infectious diseases including bacterial infections and tuberculosis.

The study appears July 24 in Nature Communications.

Many organisms, including the parasite that causes malaria, make a class of molecules called isoprenoids, which play multiple roles in keeping organisms healthy, whether plants, animals or bacteria. In malaria, the investigational drug fosmidomycin blocks isoprenoid synthesis, killing the parasite. But over time the drug often becomes less effective.

"In trials testing fosmidomycin, the malaria parasite returned in more than half the children by the end of the study," said senior author Audrey R. Odom, MD, PhD, assistant professor of pediatrics. "We wanted to know how the parasite is getting around the drug. How can it manage to live even though the drug is suppressing these compounds that are necessary for life?"

Fosmidomycin, an antibiotic, is being evaluated against malaria in phase 3 clinical trials in combination with other antimalarial drugs.

Using next-generation sequencing technology, the research team compared the genetics of malaria parasites that responded to the drug to the genetics of malaria parasites that were resistant to it. With this approach, Odom and her colleagues found mutations in a gene called PfHAD1. With dysfunctional PfHAD1, malaria is resistant to fosmidomycin.

"The PfHAD1 protein is completely unstudied," Odom said. "It's a member of a larger family of proteins, and there are almost no biological functions assigned to them."

In malaria parasites, Odom's team showed that the PfHAD1 protein normally slows down the synthesis of isoprenoids. In other words, when present, PfHAD1 is doing the same job as the drug, slowing isoprenoid manufacturing. Since isoprenoids are necessary for life, it's not clear why the organism would purposefully slow down isoprenoid production.

Ref : http://www.nature.com/ncomms/2014/140724/ncomms5467/full/ncomms5467.html

Researchers uncover how malaria parasite becomes resistant to fosmidomycin drug

Researchers test new anti-malaria medication

In continuation of my update on Fosmidomycin

Fosmidomycin  Piperaquine

An international research team has conducted successful phase II clinical tests of a new anti-malaria medication. The treatment led to a cure in 83 cases. The new combination of drugs was developed by Professor Peter Kremsner of the Tübingen Institute of Tropical Medicine and the company DMG Deutschen Malaria GmbH. The study was recently published in Clinical Infectious Diseases and is freely accessible.

In the study, the researchers tested the efficacy, tolerability and safety of a combination of the drugs Fosmidomycin and Piperaquine. The twofold medication was administered for three days to patients aged one to thirty who were infected with malaria via the Plasmodium falciparum pathogen. In the 83 evaluable cases, there was a 100% cure rate. Patients tolerated the treatment well, and it led to a swift reduction of clinical symptoms. Safety issues were limited to changes in electrocardiogram readings, as had been described for Piperaquine.

The study was conducted at the Centre de Recherches Médicales de Lambaréné (CERMEL) in the African country of Gabon; CERMEL has close ties with the University of Tübingen. Financial support came from the nonprofit organization Medicines for Malaria Venture (MMV).

"This study represents a milestone in the clinical research into Fosmidomycin," says Tübingen Professor of Tropical Medicine Peter Kremsner. The substance was originally extracted from Streptomyces lavendulae and today can be produced synthetically. It blocks a metabolic pathway for the production of Isoprenoid in the malaria pathogen. This makes the malaria pathogen unable to metabolize or reproduce. Because Isoprenoids are formed via a different synthesis path in the human body, humans have no target structures for Fosmidomycin. For this reason humans tolerate the drug well and suffer barely any side effects. In addition, this unique mechanism excludes the possibility of cross-resistance to the drugs used in earlier malaria treatments.

The new combination meets WHO guidelines for combination therapies. The two drugs mechanisms against differing target structures means that they attack the parasite in the bloodstream independently of one another. This meets WHO requirements for a fast and effective treatment of the acute phase of infection, and for protection against relapse due to reappearance of the infection. The researchers say the effective mechanism helps to delay the formation of a possible resistance. Further studies are in planning to optimize dose.

Ref : https://www.uni-tuebingen.de/en/newsfullview-landingpage/article/vielversprechender-malaria-wirkstoff-erprobt.html

Researchers test new anti-malaria medication