Merck moves tropical disease drug into phase II

Merck & Co is to see whether its oral antifungal agent Noxafil (posaconazole) can be used in chronic cases of the tropical disease Chagas.

Currently, only two drugs are approved for treatment: Roche’s Radanil (benznidazole) and Bayer’s Lampit (nifurtimox).

The manufacturer will start a phase II investigational, proof-of-concept, clinical study to evaluate Noxafil’s prospects of treating the condition, estimated to affect eight million people in Latin America.

Flagged up by the World Health Organization as one of the world’s neglected tropical diseases (NTDs), Chagas is caused by the parasite Trypanosoma cruzi, spread by insect bites.

Up to 40% of Chagas sufferers develop serious cardiac disease, digestive disease, or both as a direct result, and it is beginning to be carried via the migration of infected populations from endemic areas.

“While significant progress has been made in recent years in the prevention of the transmission of this potentially life-threatening disease, no new drugs have been approved for the treatment of chronic Chagas disease in over three decades,” said Roger Pomerantz, Merck’s global franchise head for infectious diseases.

Marketed in the European Union and US, posaconazole is currently indicated for prophylaxis of invasive Aspergillus and Candida infections in patients of 13 years and older who are at high risk of developing them.

A Schering-Plough drug prior to that company’s mega-merger with Merck, Noxafil is also approved for the treatment of oropharyngeal candidiasis (OPC).

Merck’s new study is a randomised, placebo-controlled phase II study of posaconazole oral suspension (400 mg twice daily) given for 60 days, either as monotherapy or with benznidazole.

The primary endpoint for response to treatment will be the levels of Trypanosoma cruzi in blood samples, evaluated by polymerase chain reaction.

The company plans to enroll 160 adult patients at several sites in South America and follow them for 360 days.

Last year Merck & Co signed up with the not-for-profit Drugs for Neglected Diseases initiative to find new ways of treating NTDs with an option to develop drug candidates itself.

The NTDs included visceral leishmaniasis and human African trypanosomiasis as well as Chagas.

In the 30 years to 2004, only 1.3% of new approved drugs were developed for NTDs, even though research suggests they account for 11.4% of the global disease burden.

Adam Hill