Children and young adults who receive CAR T-cell therapy for the most common childhood cancer - acute lymphoblastic leukaemia - suffer remarkably fewer relapses and are far more likely to survive when the treatment is paired with a subsequent stem cell transplant, a new study finds.

The research, with an average follow up of nearly five years, suggests that stem cell transplants offer long-term benefits for young patients who receive the cutting-edge immunotherapy.

CAR T-cell therapy results in complete remission in 60%-100% of patients initially, but the relapse rate is high.

However, among those who received a stem cell transplant after CARs, the relapse rate was less than 10% two years later.

"More than 50% of kids in other studies with a different CAR relapse, with the majority of them losing the target the CAR goes after," said researcher Daniel "Trey" Lee, MD, a paediatric oncologist and Director of Pediatric Stem Cell Transplant and Immunotherapy at UVA Children's and the UVA Cancer Center. "Most of these kids have a single shot at this life-saving and paradigm-changing therapy called CAR T-cells. We should do all we can to maximise the chance for a cure, and right now that means a transplant after CAR therapy for most."

Chimeric antigen receptor (CAR) T-cell therapy takes a person's own immune cells and genetically modifies them to make them more effective cancer killers.

The approach has shown high remission rates - up to 100% - 28 days after it is given to children and young adults with B-cell acute lymphoblastic leukaemia. But a significant number relapse, the limited data available suggests.

One study found that more than 40% had relapsed 13.1 months later.

To determine if stem cell transplants could help, the new study looked at outcomes in 50 children and young adults, ages 4 to 30.

The median age was 13.5 years.

Among the 21 who received an allogenic stem cell transplant after CARs, only 9.5% had relapsed 24 months later.

In comparison, all of those who did not receive a stem-cell transplant had relapsed.

"Even as impactful as CAR T-cell therapy is for children with relapsed leukaemia, we now know that the best outcomes happen when the child undergoes a stem cell transplant afterwards," Lee said. "Many parents turn to CAR T-cells to possibly avoid a stem cell transplant, and that is entirely understandable. But there is a window of opportunity after CARs to cure more of these incurable kids with a transplant; our study demonstrates this."

His hope for the future is for the field to be able to distinguish up front those who need a transplant and those who do not.

Source: University of Virginia Health System