Objectives: 
Eumycetoma is a chronic infectious disease characterised by a large subcutaneous mass, often caused by the fungus Madurella mycetomatis. A combination of surgery and prolonged medication is needed to treat this infection which only has success rate of 30%. Therefore, there is an urgent need to search for more effective drugs to treat this disease.

Methods: 
800 drug-like compounds from the Pathogen Box and the Stasis Box were screened for in vitro activity against M. mycetomatis hyphae at a concentration of 100µM. IC50s were determined for each of the growth inhibiting compounds and those with an IC50<5µM were verified through chemical resynthesis and further evaluated in vivo in a M. mycetomatis grain model in Galleria mellonella larvae.

Results: 
Out of 800 diverse drug-like molecules, we identified 215 molecules that were active in vitro. Minimal inhibitory concentrations were determined for the 13 most active compounds. One of the most potent compounds, a fenarimol analogue for which a large analogue library is available, led to the screening of an additional 35 compounds for their in vitro activity against M. mycetomatis hyphae, rendering 4 additional hit compounds. To assess the in vivo potency of these hit compounds, a Galleria mellonella larvae model infected with M. mycetomatis was used. Several of the compounds identified in vitro demonstrated promising efficacy in vivo in terms of prolonged larval survival and/or reduced fungal burden. 

Conclusion: 
By screening the Pathogen Box, the Stasis Box and fenarimol analogues, 14 compounds were identified which inhibited M. mycetomatis growth in vitro, 8 compounds prolonged larval survival in vivo. These results are considered the starting point of an Open Source Mycetoma (MycetOS) approach in which members of the global scientific community are invited to participate and contribute as equal partners. We hope that this initiative, coupled with the promising new hits we have reported, will lead to progress in drug discovery for this most neglected of neglected tropical diseases.

5 / Addressing the Most Neglected Diseases through an Open Research Model: the Discovery of Fenarimols as Novel Drug Candidates for Eumycetoma.