Our website uses cookies. We use cookies to remember settings and to help provide you with the best experience we can. We also use cookies to continuously improve our website by compiling visitor statistics. Read more about cookies

Higher chance for clonal hematopoiesis after stem cell transplantation

Clonal hematopoiesis typically occurs most commonly in the elderly. Researchers at the Princess Máxima Center saw for the first time that the phenomenon, a group of blood cells with the same DNA change, is also more common in children and young adults who underwent a stem cell transplant earlier in life. What this means for their health is still unknown. The team is therefore starting a follow-up study to identify the causes and consequences of clonal hematopoiesis after stem cell transplantation.  

Stem cell transplantation is an effective treatment for several diseases, including some forms of childhood leukemia. In a stem cell transplant, the blood-forming stem cells in the child's bone marrow are replaced with healthy stem cells from a donor. These donor stem cells make new blood and immune cells, which can help fight leukemia.  Since the first stem cell transplant in 1956, this treatment has become increasingly common worldwide. Every year, between 50 and 60 children at Máxima undergo stem cell transplants. Most of them recover and heal from the disease for which they were treated. Therefore, the long-term effects of the treatment are becoming increasingly important. 

Researchers at the Máxima Center examined the blood of 144 survivors who had undergone a stem cell transplant at least five years earlier, to better understand these long-term effects. This group was compared to healthy controls who had not undergone a stem cell transplant. In 23 of 144 survivors, or 16% percent, the researchers diagnosed clonal hematopoiesis, compared with 8% of individuals in the untransplanted control group.   

The results of the Long-term HIT study, made possible thanks to KiKa, were published in Blood Cancer Discovery. They are the first results of the study, which closes later this year. 

Clonal hematopoiesis 

Clonal hematopoiesis means the creation of a group, or clone, of blood cells with the same change in their DNA. Konradin Müskens, PhD candidate in the Belderbos group and first author: 'It has been known for some time that this phenomenon, which in the healthy population occurs mainly in people over 60, is more common in children after chemotherapy treatment. It is extraordinary that we find clonal hematopoiesis more often after stem cell transplantation. After all, the transplanted stem cells have not been exposed to chemotherapy.'  

The researchers searched for an explanation for the increased risk. They found that the age of the donor stem cells is an important risk factor for clonal hematopoiesis. Müskens: 'This is actually quite logical. Clonal hematopoiesis is age dependent. In a stem cell transplant, the child receives the stem cells from the donor. So, if a young child is transplanted with a stem cell from a twenty-year older donor, the stem cells after transplantation - and the resulting blood - are twenty years older than the child itself. Yet this does not explain everything. In addition to donor age, the stem cell transplant itself also increased the risk of clonal hematopoiesis. Why this is so we do not know. Follow-up research should determine why this happens.' 

Impact   

The discovery of the increased risk of clonal hematopoiesis after stem cell transplantation is an important first step. Little is still known about the health effects of clonal hematopoiesis after stem cell transplantation. In healthy, untransplanted elderly people, clonal hematopoiesis is associated with an increased risk of health problems, such as cardiovascular disease and leukemia. At the same time, there is also evidence that clonal hematopoiesis can promote post-transplant recovery.    

Dr. Mirjam Belderbos, principal investigator, pediatric oncologist and research group leader currently sees no reason for additional screenings in survivors at the LATER clinic at the Máxima Center. She explains: ‘We still know little about the impact of clonal hematopoiesis on health after stem cell transplantation. With our follow-up research, we want to better understand which factors contribute to the development of clonal hematopoiesis after transplantation and what the consequences are. Ultimately, my goal is to use stem cell transplantation as a treatment as effectively as possible so that we can cure children with optimal quality of life.’   

Are you or is your child undergoing (or has been undergoing) treatment and have questions about this study? Check out the Question & Answer page or contact your treating physician or the LATER clinic