Kids with a rare bone cancer might live longer if prescribed a drug that blocks blood supply to tumors, researchers say.

The drug pazopanib (Votrient) extended the lives of a small group of kids with Ewing sarcoma, which causes cancerous tumors in their bones, researchers report in the journal Frontiers in Oncology.

“While we wait for new treatment options, it is possible to implement this existing drug to improve outcomes in very high-risk patients,” lead researcher Anna Raciborska, head of oncology at Poland’s Warsaw Mother and Child Institute, said in a news release. “It opens the door to targeted therapies earlier in the disease course, potentially improving survival and quality of life.”

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Typically, fewer than a quarter of children with advanced Ewing sarcoma survive five years after their diagnosis, researchers said in background notes.

But the research team thought that pazopanib, which was initially developed for kidney cancer, might also be effective in staving off Ewing sarcoma.

“Pazopanib is a pill that blocks the tumor's ability to grow new blood vessels, which tumors need to survive and spread,” Raciborska said. “By cutting off this ‘blood supply,’ the drug presumably makes tumors weaker and more sensitive to chemotherapy and radiation. This may slow down the disease and help existing treatments work better.”

Between 2016 and 2024, 11 children ages 5 to 18 were given pazopanib alongside the standard treatments for their cancer, which can include chemo, surgery, radiation therapy or stem cell transplants.

About 86% of the children survived two years after their diagnosis, results showed.

Further, two-thirds (68%) saw no progression in their cancer, researchers said.

At this point, 10 of the children are still alive, and six are still taking pazopanib, researchers said. One child’s cancer has progressed, and two have suffered a relapse.

Pazopanib also produced minimal side effects, researchers said.

More research is needed to validate these results, the authors said, but advanced Ewing sarcoma is so rare that it can be difficult to recruit enough patients for larger clinical trials.

“While the results are encouraging, larger controlled trials are needed before changing standard practice,” Raciborska said. “Our study could serve as a basis for creating prospective, multicenter clinical trials to confirm these promising results. However, this requires a lot of work and the commitment of resources.”