Cure of Hookworm Infection with a Cysteine Protease Inhibitor

Abstract

BackgroundHookworm disease is a major global health problem and principal among a number of soil-transmitted helminthiases (STHs) for the chronic disability inflicted that impacts both personal and societal productivity. Mass drug administration most often employs single-dose therapy with just two drugs of the same chemical class to which resistance is a growing concern. New chemical entities with the appropriate single-dose efficacy are needed.Methods and FindingsUsing various life-cycle stages of the hookworm Ancylostoma ceylanicum in vitro and a hamster model of infection, we report the potent, dose-dependent cidal activities of the peptidyl cysteine protease inhibitors (CPIs) K11002 (4-mopholino-carbonyl-phenylalanyl-homophenylalanyl- vinyl sulfone phenyl) and K11777 (N-methylpiperazine-phenylalanyl-homophenylalanyl-vinylsulfone phenyl). The latter is in late pre-clinical testing for submission as an Investigational New Drug (IND) with the US Federal Drug Administration as an anti-chagasic. In vitro, K11002 killed hookworm eggs but was without activity against first-stage larvae. The reverse was true for K11777 with a larvicidal potency equal to that of the current anti-hookworm drug, albendazole (ABZ). Both CPIs produced morbidity in ex vivo adult hookworms with the activity of K11777 again being at least the equivalent of ABZ. Combinations of either CPI with ABZ enhanced morbidity compared to single compounds. Strikingly, oral treatment of infected hamsters with 100 mg/kg K11777 b.i.d. (i.e., a total daily dose of 200 mg/kg) for one day cured infection: a single 100 mg/kg treatment removed >90% of worms. Treatment also reversed the otherwise fatal decrease in blood hemoglobin levels and body weights of hosts. Consistent with its mechanism of action, K11777 decreased by >95% the resident CP activity in parasites harvested from hamsters 8 h post-treatment with a single 100 mg/kg oral dose.ConclusionA new, oral single-dose anthelmintic that is active in an animal model of hookworm infection and that possesses a distinct mechanism of action from current anthelmintics is discovered. The data highlight both the possibility of repurposing the anti-chagasic K11777 as a treatment for hookworm infection and the opportunity to further develop CPIs as a novel anthelmintic class to target hookworms and, possibly, other helminths.

A Cysteine Protease Inhibitor Rescues Mice from a Lethal Cryptosporidium parvum Infection

“…Targeting pathogen proteases for therapy has been successful in the control of HIV infection (63) and has spurred the search for novel protease inhibitors to treat other infectious diseases. Indeed, over the last 20 years, small-molecule inhibitors of clan CA cysteine proteases from parasites have been validated as drug leads for amelioration, if not cure, of many protozoan (64) and helminthic (35,36) diseases.…”

“…Orthologous cathepsin L-like proteases are validated as promising therapeutic targets in extensive in vitro and in vivo studies with the malaria parasite Plasmodium falciparum (31,32) and the etiological agent of Chagas' disease, Trypanosoma cruzi (33). In particular, investigations with small-molecule inhibitors targeting parasite clan CA enzymes have shown much promise for their eventual use in the therapy of these and other parasitic diseases (32)(33)(34)(35)(36).…”

In vitro Screening of Compounds against Laboratory and Field Isolates of Human Hookworm Reveals Quantitative Differences in Anthelmintic Susceptibility

“…[6][7][8][9] However, novel compounds identified using small animal models of hookworm infection are rarely screened for comparable activity against field isolates of human hookworms. [10][11][12][13][14][15][16] Therefore, the correlation between the anthelmintic activity of compounds against laboratory and field isolates of human hookworms remains largely unknown.…”

Development of a New Antileishmanial Aziridine-2,3-Dicarboxylate-Based Inhibitor with High Selectivity for Parasite Cysteine Proteases

“…Cysteine proteases (CPs) of parasites such as Plasmodium, Trypanosoma, and worms are druggable targets for developing a new promising strategy for chemotherapy based on protease inhi-bition (9)(10)(11)(12). Therefore, the identification and synthesis of highly selective protease inhibitors might be a promising means for the treatment of such infections in future.…”

“…In recent years, we have been working on the development of inhibitors of papain-like CPs belonging to the CAC1 family (13)(14)(15)(16)(17)(18). These proteases may represent attractive targets because of their key roles in parasite infections (9)(10)(11)(12). The Leishmania major genome encodes a total of 65 CPs, grouped into 4 clans [CA, CD, CF, and PC(C)] and 13 families.…”