New drugs failing to keep pace with TB growth

The number of new anti-TB drugs under development is 'startlingly low', says Pharmaprojects, a database tracking pharmaceutical development.

At a time when TB has been put in the spotlight by the World Health Organisation, Pharmaprojects reports that there are just 22 active TB drugs under development by pharmaceutical companies worldwide.

Officially declared a global emergency by the WHO in 1993, one third of the world's population - 2bn people - are thought to be infected with the Mycobacterium tuberculosis pathogen, and TB is the largest cause of death from any single infectious disease. According to Pharmaprojects, there has been a rise in the number of TB therapeutics under development since 1995, but the numbers are in no way keeping pace with the growing problem of TB.

The sequencing of the M. tuberculosis genome is beginning to yield results, however. Axxima is one company developing TB therapeutics against a novel target discovered through its genomics/proteomics drug discovery platform. Meanwhile a drug discovery programme being carried out by Lupin has so far yielded three preclinical compounds, says Pharmaprojects, and Phage Genomics is developing a bacteriophage product.

Important developments are also taking place in vaccine programmes, with Corixa and GlaxoSmithKline having started Phase I safety testing of their recombinant TB vaccine. This is the first new TB vaccine to be tested in humans in the US in more than 60 years, and is the first recombinant TB vaccine ever to be tested in humans. Hot on its heels is Oxxon Pharmaccines' vaccine candidate, which entered clinical trials earlier this year.

A number of factors contribute to a general reluctance for industry investment in anti-infectives, not least the limited financial returns on drugs that are used in an acute setting. Furthermore, only 5% of TB sufferers can afford treatment. While patient numbers are huge, the global TB market is estimated at only US$500m. According to Pharmaprojects, just 50 TB development programmes have been pursued in the 20+ years that the database has been tracking pharmaceutical r&d. The lack of commercial motivation is compounded by a significant attrition rate: of the 50 TB programmes mentioned, 27 have been abandoned.