A brain tumor shrank 100 percent, and stayed gone

A Stanford team led by Michelle Monje engineered patients' own immune cells to hunt a protein called GD2 on the tumor's surface, then delivered them first through a vein and later straight into the fluid around the brain.

Of thirteen patients enrolled, eleven received the cells. Four had major tumor shrinkage of 52, 54, 91, and 100 percent on imaging. The patient whose tumor shrank completely stayed in remission for more than thirty months, and nine showed neurological improvement.

GD2 marks these tumors but also appears on some normal tissue, and higher doses triggered dangerous cytokine release and brain swelling that required intensive care. Only one of thirteen patients reached a complete response, and this was a small, early-phase safety trial without a comparison group. Researchers are now testing whether earlier or repeated dosing can make full responses less rare.

One tumor vanished, most did not.