Drugs that block the hedgehog signalling pathway may prove useful in treating chronic myelogenous leukaemia (CML), a study in Nature suggests.

The hedgehog signalling pathway helps to maintain leukaemia stem cells, which are the very cells that spread the disease, Tannishtha Reya and colleagues report. When a small inhibitory molecule is used to disrupt the pathway in a mouse model, the cancer stem cells become depleted.

Hedgehog, more commonly known for its role in embryonic patterning, has been implicated in several cancers, including CML. The blood cancer is commonly treated with a drug called imatinib, but CML stem cells seem to be resistant to the therapy and CML cells can acquire drug resistance due to additional mutations. Therefore imatinib often stalls but does not cure the disease. The small molecule used in this study, cyclopamine, targets normal and drug-resistant CML cells and stem cells, raising hopes that molecules like this will be useful in CML treatment.