17Entamoeba histolytica is a protozoan parasite which infects approximately 50 million 18 people worldwide, resulting in an estimated 70,000 deaths every year. Since the 1960s E.19 histolytica infection has been successfully treated with metronidazole. However, drawbacks to 20 metronidazole therapy exist, including adverse effects, a long treatment course, and the need 21 for an additional drug to prevent cyst-mediated transmission. E. histolytica possesses a kinome 22 with approximately 300 -400 members, some of which have been previously studied as 23 potential targets for the development of amoebicidal drug candidates. However, while these 24 efforts have uncovered novel potent inhibitors of E. histolytica kinases, none have resulted in 25 approved drugs. In this study we took the alternative approach of testing a set of twelve 45 both amoebicidal and cysticidal activities may be used to treat amoebiasis, especially in cancer 46 patients or in life-threatening brain-and liver-infecting forms of the disease.47 65 which has been in use since the 1960s and has widespread use as a treatment against 66 anaerobic microbial infection (7, 8). However, while successful, metronidazole is not a perfect 67 solution to E. histolytica infection, with a few particularly notable existing issues. One of these is 68 problems with lack of patient compliance with the full course of treatment, leading to relapses 69 and increased disease spread (7). This is possibly due to factors such as drug adverse effects 70 or the need for continued dosing past the resolution of disease symptoms (9, 10). Another issue 71 is metronidazole's inability to kill the infective cyst stage of E. histolytica. Because of this, along 72 with its complete absorbance from the intestines, metronidazole must be followed by a 73 secondary luminal amoebicide such as paromomycin to prevent spread of the disease (11, 12).
74Also concerning is the potential for the emergence of resistance to metronidazole, which has 75 been previously observed in the laboratory (13). When considered together, these factors 76 comprise an unmet need for alternative amoebiasis therapies. 93 published a computational tool capable of such mapping for antineoplastic drugs, including a 94 large number of kinase inhibitors (20). We describe here the use of this tool to prioritize 95 molecules for screening against E. histolytica trophozoites based on initial hits from a small 96 primary screen. In total, 6 antineoplastic kinase inhibitors (AKIs) were found to have potent and 97 rapid anti-amoebic activity. The results of these experiments demonstrate the promise of using 98 target-based analysis to leverage compounds with multi-target pharmacology against a human 99 parasite. 100 101 Materials and Methods 5 102 103 E. histolytica cell culture 104 E. histolytica strain HM-1:IMSS trophozoites were maintained in 50ml culture flasks 105 (Greiner Bio-One) containing TYI-S-33 media, 10% heat-inactivated adult bovine serum 106 (Sigma), 1% MEM Vitamin Solution (Gibco), supplemented with penici...