Sanofi and TB Alliance have agreed to explore analogs of a TB-active natural product that was identified as a starting point of interest through a literature search. Early data indicate that this series has potent activity against Mycobacterium tuberculosis (M.tb), including drug-resistant M.tb. The compound was originally discovered more than 20 years ago but was never developed; it is now being revisited using state-of-the-art technology. The key objective of the hit-to-lead program is to identify a lead molecule from this series that is efficacious in a mouse model of TB when given orally.