The TB drug pipeline evolves from a discovery phase, which yields single promising TB drug candidates that are selected into the preclinical development phase. The aim of the preclinical development phase is to determine (mainly by studies in animals) if the selected agent is likely to be safe and effective against TB in humans. Next, TB drug candidates move into the phase of clinical development, which is subdivided in phase I (safety, tolerability and pharmacokinetics in healthy volunteers), phase II (safety and efficacy in small groups of TB patients) and phase III (randomized controlled trials in large patient groups to demonstrate the efficacy of the TB drug candidate).
Discovery phase and preclinical development phase
The portfolio of the discovery phase represents a large range of targets and approaches. There are currently relatively few (<10) compounds in formal preclinical development. This raises concerns for the near- to mid-term health of the clinical portfolio.
There are currently at least 12 drugs in various stages of clinical evaluation for TB. They can be divided into several categories:
1) Novel drugs being developed for TB treatment.
2) Current first-line TB drugs being re-evaluated to optimize their efficacy.
3) Currently licensed drugs for other indications being re-purposed for TB and their ‘next generation’ chemical derivatives.