A protein is found to drive brain cancer. You develop inhibitors of the protein. The inhibitors put the brakes on cancer in early studies. And voila! You’re on the road to a new cure, right?

Well, sometimes biology sends you a curve ball.

The protein Ezh2 has been found to be overexpressed in an aggressive childhood brain tumor called medulloblastoma. In fact, inhibitors of Ezh2 are already in early Phase I/II clinical trials.

But in an unexpected twist, St. Jude scientists have used gene-editing technology to show that sometimes Ezh2 can also suppress cancer. To make things more complicated, Ezh2 seems to behave differently depending on the specific type of cancer.

“These recent findings sound a cautionary note and suggest that inhibiting Ezh2 could be counterproductive for cancer treatment in certain situations,” says Martine Roussel, PhD, of St. Jude Tumor Cell Biology.

The results, published in Cell Reports, have implications for early-stage drug development studies that are already underway.

Read more about the research.