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Towards personalized stem cell transplants together

18 mei 2026

By bringing together research data from hundreds of children in Europe and the United States, personalized stem cell transplantation is coming closer. PhD candidate Alexandre Troullioud Lucas helped build an international collaboration that enables researchers to more quickly discover which treatment is the best fit for a child. 

Each year in the Netherlands, forty to fifty children receive a stem cell transplant as treatment for their disease, including cancer. Many factors play a role in how well the treatment works, such as the transplant itself, medications given before, during and after the transplant, the recovery of the immune system, and the possible related infections and complications. 

With so many different factors determining the success of the treatment, it is very difficult to properly understand which approach works best for each child. A large amount of research data is needed for this. Data from Dutch children alone is not sufficient. That is why the Princess Máxima Center works with transplant centers in Europe and the United States within the IMPACT consortium. 

PhD candidate Alexandre Troullioud Lucas helped further expand this collaboration during his doctoral research. As a result, research data can now and in the future be better shared and studied between different centers. 

‘Sharing and then studying these data acts as a flywheel for stem cell transplantation research,’ says Troullioud Lucas, who worked from the Nierkens group at the Máxima Center and the group of Dr. Jaap Jan Boelens at Memorial Sloan Kettering Cancer Center (MSK) in New York. 

Data from five hundred children 

For his research, Troullioud Lucas combined data from children at the Máxima Center, Memorial Sloan Kettering Cancer Center and St. Jude Children’s Research Hospital. In total, he studied data from five hundred children who underwent a stem cell transplant over a ten-year period. 

Within this dataset, he looked for so-called clinical predictors for the occurrence of complications after a stem cell transplant and related these to the speed of immune system recovery. These insights may help determine the best-fitting stem cell transplant approach in the future. ‘By sharing data and learning from each other, we can gain new insights more quickly for children who need a stem cell transplant.’ 

Troullioud Lucas received his PhD on 11 May at Utrecht University. After completing his PhD, he will continue working on research within the consortium and as a stem cell transplant physician at MSK in New York. His research was made possible thanks to an NIH/NCI Cancer Center Support Grant. 

Clinical predictors and immune recovery 

With the data collected by researchers within the European-American IMPACT consortium, they ultimately aim to establish a set of clinical predictors for the effectiveness of a hematopoietic stem cell transplant. Combined with biological markers, such as immune recovery, this may contribute to a more personalized treatment for children undergoing a stem cell transplant. 

Previously, researchers from the research group of Dr. Stefan Nierkens identified a biological marker that predicts the degree of transplant success: the CD4+ T-cell count within the first 3 months after transplantation. This parameter predicts outcomes in children who develop graft-versus-host disease or a life-threatening viral infection after a stem cell transplant. The marker has since been officially recognized by the U.S. Food and Drug Administration (FDA) as an endpoint in clinical studies. 

Foundation for follow-up research 

Thanks to the international collaboration, the consortium has access to larger patient cohorts. This allows researchers to apply statistical corrections for differences in treatment methods and laboratory analyses between centers, and therefore make better statements about which treatments can be adjusted to stimulate optimal immune recovery and clinical outcomes. The methodological approach developed by Troullioud Lucas for this also forms a foundation for future studies within the consortium. One next study is specifically focused on investigating the recovery of thymus function to accelerate immune recovery after transplantation. 

Faster translation to the clinic 

Through the collaboration between the six international centers, knowledge can be translated more quickly into clinical practice, with the shared goal of achieving more successful hematopoietic stem cell transplants for children with cancer, metabolic diseases or blood disorders. 

Within the IMPACT consortium, which stands for Immune and Microbiota Partnership for Cellular Therapy, six pediatric transplant centers collaborate: 

  • Princess Máxima Center – The Netherlands 

  • Ospedale Pediatrico Bambino Gesù – Italy 

  • Memorial Sloan Kettering Cancer Center – United States 

  • Boston Children’s Hospital – United States 

  • Stanford University – United States 

  • St. Jude Children’s Research Hospital – United States