Certain combinations of drugs might kill drug-resistant tumours, and a method based on the CRISPR–Cas9 gene-editing system offers a way to find them.

Tumours often become resistant to individual drugs, leading clinicians to use combinations of medicines in the hope of thwarting resistance. Michael Bassik and his colleagues at Stanford University in California developed a method that systematically disables two genes at a time in cells. They used the system to knock out 21,321 pairs of potential drug targets in leukaemia cells, looking for combinations that work synergistically to kill cancer cells.

The team found that disabling two genes called BCL2L1 and MCL1 killed drug-resistant cells. Drugs that inhibited the proteins encoded by these genes killed more leukaemia cells than each of the two medicines did individually.

Nature Biotechnol. http://dx.doi.org/10.1038/nbt.3834 (2017)