On Feb. 17, 2025, researchers from Texas Children’s Hospital in Houston announced that the four year old girl who received a highly experimental therapy nineteen years ago for nerve-cell cancer has the longest reported cancer remission following treatment with engineered immune cells called CAR T cells.

In the years since the girl’s treatment in 2006, CAR T cells have produced stunning results in some blood cancers such as leukaemia. Seven CAR-T-cell therapies have been approved by the US Food and Drug Administration since 2017, and some early recipients of CAR-T therapy have been cancer-free for more than a decade.

CAR T cells are immune cells that have been engineered to make a protein called a chimeric antigen receptor (CAR). This protein is designed to latch onto a target found on a cancer cell, triggering the immune cell to attack and destroy it.

But researchers have struggled to repeat that success against solid tumours such as those caused by neuroblastoma, a nerve-cell cancer that is typically diagnosed in young children. That makes the latest results particularly good news, says Sneha Ramakrishna, a paediatric oncologist and cancer researcher at Stanford University School of Medicine in California, who was not involved in the study.

“This provides me with a lot of hope,” she says. “We’re going to unlock CAR T cells for people with solid tumours.”