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Anjan Debnath, a leader of the CDIPD Amoebozoa Core, conducts his groundbreaking reseach in the UCSD Skaggs School of Pharmacy and Pharmaceutical Sciences.

Drug discovery for amebiasis, caused by the intestinal parasite Entamoeba histolytica, has been hindered by the absence of real assay development suitable for high-throughput screening. To accelerate the identification of new drug leads for amebiasis, we developed a novel high-throughput screen that could be conducted in an oxygen-free environment in microtiter plates, mimicking ameba's natural habitat. A screen of a library with 910 compounds, consisting of FDA-approved drugs and unapproved bioactive compounds, identified auranofin as the most potent of all and the drug was 10 times more effective in culture than metronidazole. We selected auranofin for follow-up studies because auranofin is an FDA-approved drug and has been in clinical use to treat rheumatoid arthritis since 1985, secondly, this drug is taken orally, and finally it is relatively cheap. In the animal model of amebic colitis a single oral dose of 1 mg/kg/day for 7 days significantly reduced the number of parasites and the detrimental host inflammatory response but not by similar dose of metronidazole, the current drug of choice. Similarly, a low dose of oral auranofin for 7 days significantly reduced the liver damage in the animal model of amebic liver abscess but same dose of metronidazole had no effect on liver abscess progression. Based on these findings, auranofin has now received an Orphan Drug status from the FDA for the treatment of amebiasis. Since the drug is off-patent and has been in clinical use for more than 25 years, the cost and development time for this "repurposed drug" can be significantly reduced. This cost saving is important in the context of the disease afflicting the poor.

Since our discovery of auranofin as a new drug lead for E. histolytica our collaborators looked at its efficacy for related organisms and showed efficacy of auranofin against other parasites such as diarrheal parasite Giardia infecting 280 million people worldwide each year, another diarrheal parasite Cryptosporidium affecting 500 million people, sexually-transmitted parasite Trichomonas vaginalis infecting 174 million people worldwide every year, adult worm Brugia that causes disfiguring lymphatic filariasis, also known as elephantiasis and infecting 128 million people and another adult worm Onchocerca that causes river blindness and infects 37 million people. Altogether, auranofin showed efficacy against these parasites infecting about 1 billion people worldwide.

Auranofin is now poised for clinical trials in Bangladesh for amebiasis and giardiasis. If successful in clinical trial, auranofin could be the first new drug with a defined target for the treatment of amebiasis and giardiasis affecting more than 300 million people each year.

by Dr. Anjan Debnath, UCSD

Press Releases:

UCSF News: Lab tests show arthritis drug effective against global parasite

UCSF School of Pharmacy: Teaching old drugs new tricks at the Small Molecule Discovery Center

UCSD News: Drug found for parasite that is major cause of death worldwide

UC Health: Arthritis drug effective against global parasite

University of California: Persistence, passion lead to new attack on parasitic diseases

Nature Medicine: Repurposing an old drug for amebiasis

BBC News: Cheap amoebic dysentery drug 'promising'

Huffington Post UK: Arthritis drug may cure dysentery

Los Angeles Times: Inexpensive arthritis drug may treat dysentery, giardiasis

New York Daily News: Cheap arthritis drug effective against killer parasites? Arthritis drug, Auranofin, may be effective against amebiasis and Giardia

RedOrbit: Arthritis drug powerful against human dysentery

ScienceDaily: Arthritis drug effective against global parasite, study suggests

Science World Report: Arthritis drug offers cheap cure for dysentery

Drug Discovery and Development Magazine: Arthritis drug attacks dysentery bug

Medical News Today: Dysentery may be treatable with cheap arthritis drug

National Health Service (UK): Dysentery drug shows early promise

The Telegraph (India): Dysentery cure in arthritis pill - Calcutta-born scientist finds drug link (India): Arthritis drug could help combat dysenteric death

Pune Mirror (India): Old arthritis drug to combat killer parasites

Newstrack India: Arthritis drug is able to fight dysenteric death worldwide

China Daily: Cheap drug treats amoebic parasite patients

The China Post: Old drug for arthritis also effective against killer parasites

Arzte Zeitung (Germany): Rheuma-Mittel gegen Amoben

Wissenschaft aktuell (Germany): Arthritis-Mittel wirkt gegen Amoben

South African Press Association (SAPA): Cheap drug could treat parasitic disease

Spanish Scientific News Agency (SINC): Un farmaco barato contra la artritis combate la disenteria amebiana

Correo del Orinoco (Venezuela): Farmaco barato contra la artritis combate la disenteria amebiana

Collaborative Drug Discovery: Is it really that easy to find a new inexpensive drug?

In the Pipeline: A new way to kill Amoebas, from an old drug