Now doctors have made progress with an unusual treatment: Dripping millions of copies of a virus directly into kids’ brains to infect their tumors and spur an immune system attack.

A dozen children treated this way lived more than twice as long as similar patients have in the past, doctors reported Saturday at an American Association for Cancer Research conference and in the New England Journal of Medicine.

Gregory Friedman, a childhood cancer specialist at the University of Alabama at Birmingham.

A suburban Philadelphia company called Treovir developed a treatment by genetically modifying the virus so it would infect only cancer cells.

Through tiny tubes inserted in the tumors, doctors gave the altered virus to 12 patients ages 7 to 18 whose cancer had worsened after usual treatments.

He lived for a year and four months after that,” long enough to celebrate his bar mitzvah, go with his family to Hawaii and see a brother be born, said his father, Josh Kestler, a financial services executive from Livingston, New Jersey.

Jake died April 11, 2019, but “we have no regrets whatsoever” about trying the treatment, said Kestler, who with his wife has started a foundation, Trail Blazers for Kids, to further research.

“It’s a devastating disease for these patients and their families,” and the early results suggest the virus treatment is helping, but they need to be verified in a larger study, which doctors are planning, said Dr.