BREAKTHROUGHS BLOG

June 26, 2016

Research Roundup: TB drug development, mosquitoes’ secret weapon, and a new platform for antibiotic R&D

Senior Program Assistant
GHTC
Photo: National Institute of Allergy and Infectious Diseases (NIAID)

TB Alliance announced last week a new agreement with Takeda Pharmaceutical Company Limited to advance novel compounds that show promise as potential treatments against tuberculosis (TB). The compounds were first identified through a recent program in which the partners screened the entirety of Takeda’s chemical library, comprised of 20,000 unique compounds. Existing TB treatment regimens can be onerous for both patients and health systems, requiring four pills per day for at least six months, and only 50 percent of patients with drug-resistant TB are cured after a two-year regimen with more toxic drugs. New drugs against TB are critically needed, and TB Alliance has not only developed multiple products, but has the largest pipeline of TB medicines in history. Both the screening program and the research moving forward are supported by the Global Health Innovative Technology (GHIT) Fund, a cross-sector partnership that invests in research and development for neglected diseases.

For years, experts have known that mosquitoes are more effective at transmitting disease than a scientist with a needle, and new research suggests that the key is in the insect’s saliva. To study the impact of mosquitoes' saliva, researchers at the University of Leeds first injected a close relative of the chikungunya virus into mice, recording few symptoms and zero deaths. Next, the team allowed uninfected mosquitoes to bite the mice, and then scientists injected the virus into the mice through the site of the bite. The infection proved to be more virulent, and more than a third of the mice died. Molecules in the saliva prompt an inflammatory response, as the immune system sends neutrophils and macrophages—which combat pathogens by consuming them. The team determined that certain viruses are able to infect the macrophages, enabling the virus to replicate and travel throughout the body.

Researchers at Harvard University have created a platform for rapidly and prolifically generating macrolides, a class of compounds containing some of the most common antibiotic and antifungal medicines. Macrolides were first developed in the 1950s, by tweaking microorganisms with antimicrobial properties to make them more effective and safe for use in humans. However, reliance on these natural microorganisms has made it difficult to produce new macrolides or adapt existing ones, and past efforts to develop synthetic macrolides have involved more than fifty steps—an arduous process with no guarantee that the final product will be effective. However, the team at Harvard has developed eight synthetic structures and has designed a method for rapidly combining them, and using just these eight structures and their derivatives, have created more than 300 synthetic macrolides. The team has begun to screen these macrolides for activity against different bacteria, and have identified two that are active against a bacterium that has developed resistance to vancomycin, which is considered an antibiotic of last resort. One drug candidate developed using this technique has recently been tested in two phase 3 clinical trials, proving to be effective against advanced intra-abdominal infections but ineffective against complicated urinary tract infections. The team will continue to screen the more than 300 synthetic macrolides, advancing those that prove most promising in the lab.

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