Tropical Parasitic Diseases Unit (TPDU)

Dr Simon Townson (Director)

The TPDU occupies a highly specialized position, concerned with research on the discovery and development of new drugs for the treatment of tropical parasitic diseases, sometimes described as neglected tropical diseases, with particular emphasis on onchocerciasis (River Blindness), lymphatic filariasis (Elephantiasis) and malaria. These diseases are transmitted through the bites of insect vectors, and infect countless millions of often poor people across the tropical countries of the world, causing a huge amount of morbidity and in the case of malaria, mortality. The work of the TPDU has been entirely funded from competitively obtained major project grants from the World Health Organization, The Bill and Melinda Gates Foundation, the Drugs for Neglected Diseases Initiative (Geneva) and others including big pharma. The TPDU is based at NPIMR, but also works extensively at laboratories in Gambia and Ghana in W. Africa.

Our current focus is on drug discovery for onchocerciasis and lymphatic filariasis. Existing treatments for both of these diseases urgently need new and more effective drugs. In searching for new approaches, our collaborations include universities, research institutions and the pharmaceutical industry. Many new leads have been identified from both novel chemical compounds and from existing drugs with the potential for re-purposing. Early initiatives from the TPDU lead to contracts and projects to take forward the veterinary drugs Moxidectin (Cyanamid) and Emodepside (Bayer), for possible use against human diseases.

Moxidectin development was adopted by the WHO which took the drug through pre-clinical studies and clinical trials for onchocerciasis, which demonstrated that Moxidectin, although not curative, suppressed the infection and prevented further transmission, a significant improvement over existing treatments. Moxidectin was finally approved by the FDA in 2018, and there are initial plans for its use in the Democratic Republic of Congo.

Emodepside development, supported by Bayer, is also making good early progress, and has successfully completed phase 1 clinical trials in uninfected subjects.

Some years back the TPDU was involved with a large project in collaboration with the Liverpool School of Tropical Medicine and the University of Bonn, to develop an antibiotic to target the endosymbiotic bacteria (Wolbachia) which live within the tissues of the filarial parasites. This was a completely new approach, following earlier studies which demonstrated that treatment with the antibiotic Doxycycline eliminated the bacteria which then subsequently affected the survival of the parasite. The project identified a novel compound with excellent activity, owned by the US drug company Abbvie. This compound has recently successfully completed phase 1 clinical trials.

In 2019, the Unit is working on libraries of novel compounds supplied and funded by the US drug company Celgene and the Drugs for Neglected Diseases Initiative. This work is carried-out in our laboratories in Gambia where there is a plentiful supply of Onchocerca parasites. Early results indicate a rich seam of activity has been identified.