Dr Caroline Lindemans is a paediatrician specializing in stem cell transplants at the Princess Mxima Center and the Wilhelmina Children’s Hospital in Utrecht, the Netherlands, and one of the study’s co-leading authors.
She explains: ‘The better the immune system recovers after a transplant, the better a child’s chances of survival. We suspected that too high a dose and wrong timing of giving a child ATG, one of the drugs that help prepare for a stem cell transplant, could hinder the donor immune cells.’
In the past, the dose of ATG was determined based on body weight. Before the stem cell transplant, the number of immune cells is also included in choosing the correct amount for each child in the new study.
Some 58 children who received a stem cell transplant between 2015 and 2018 at the Wilhelmina Children’s Hospital or the Princess Mxima Center took part in the study.
Dr Rick Admiraal, one of the researchers on the team, compared the immune recovery and survival of these patients with that of children previously treated with the standard dose of ATG.
In 4 out of 5 children, the immune system fully recovered within 100 days of the stem cell transplant. A similar proportion survived for at least three years after the stem cell transplant.
‘That is a clear improvement compared to outcomes with the standard dose,’ says Admiraal. ‘There, we saw immune recovery and three-year survival in about two-thirds of children.’
Lindemans: ‘As we had hoped, our results show that an individual dose of ATG leads to better immune recovery. The risk was that the donor stem cells would be rejected in more children, but fortunately, that turned out not to be the case.
Therefore, our research shows that this method of dosing medicines makes stem cell transplants safer.’