Pharmaprojects highlights the current dearth of pharmaceuticals in development for protozoal diseases
26th September 2006
On the opening of the 46th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in San Francisco, Pharmaprojects, the world's leading source of business-critical intelligence on drugs in global R&D, today highlights the notable lack of drugs in development to treat non-malarial protozoal infections.
The latest information shows that of 125 products known to have been in development for non-malarial protozoal infections since 1980, only 14 are currently in active development. A further 9 have been launched, while 102 are reported to have ceased development. Of the 102 ceased products, 38 have been positively confirmed as discontinued.
Of those drugs in the current pipeline, aminosidine (developed by the Institute for OneWorld Health) was submitted for registration in India for the prevention of leishmaniasis and was approved only a few weeks ago.
The other compounds, mostly focus on trypanosomiasis (6 products), while 4 tackle leishmaniasis. There are also 2 products, one in preclinical trials and one in Phase II clinical trials, that only suggest a possible use as an antiprotozoal, their main focus being on anticancer uses.
Of the launched products, 3 are for leishmaniasis, 2 for trypanosomiasis [1 for the American (also known as Chagas disease) variant, and the other for the African (sleeping sickness) variant], and 2 for trichomoniasis and amoebiasis. The final launched product is nitazoxanide which was launched in Mexico in 1996 followed by other South American countries and the US in 2003 for the treatment of cryptosporidiosis, helminth infections and giardia. This is currently in Phase III trials for the treatment of Clostridium infections and in Phase II trials for hepatitis-C and Crohn's disease.
This data highlights the sparse nature of the pharmaceutical pipeline of drugs designed to treat infections caused by protozoa: unicellular eukaryotic organisms that mainly cause diseases in tropical climates. The most notable of these infections are malaria, giardiasis, trichomoniasis, trypanosomiasis, leishmaniasis, amoebiasis, balantidiasis and cryptosporidium. While malaria has received a lot of input and there are many treatments available, other diseases seem to have received much less attention. One possible reason for this could be the fact that these conditions occur mostly in the poorer developing world countries, where pharmaceutical companies would find it more difficult to make a profit.
Giardiasis, an infection caused by Giardia lamblia in the small intestine, is believed to chronically infect up to 20% of the world's population. It is also the most common cause of water-borne parasitic infection in the US, normally occurring there as a result of travel to less-developed countries (eg. Mexico, Southeast Asia).
Leishmaniasis, carried by the phlebotomine sandfly, currently threatens 350 million people in 88 countries, most of those being African, South American or Asian. This pathogen has a range of clinical symptoms; cutaneous, which presents as skin lesions which cause severe disability; mucocutaneous, lesions of the mucous membranes of the nose, mouth and throat cavities and surrounding tissues; and the most severe form, visceral. In visceral leishmaniasis, the infection affects the gut and, if left untreated, causes 100% fatality within 2 years.
Cryptosporidium parvum has become widely known for its occurrence in immunocompromised people, most notably those with AIDS. The parasite has been found to affect the gall bladder and respiratory system, and in healthy subjects produces acute diahorrhoea and associated symptoms for up to 2 weeks.
Trypanosomiasis takes on two forms: Chagas' disease in South and Central America, where it affects 21 countries with 16-18 million infected people; and sleeping sickness in sub-Saharan Africa where 36 countries and an estimated 500,000 people are confirmed to be infected. There are currently drugs available to treat these diseases, but most are old and difficult to administer in resource-poor conditions. Success rates of treatment are also variable.
