The clinical implications of clonal hematopoiesis in hematopoietic cell transplantation

Clonal hematopoiesis (CH) describes somatic mutations in hematopoietic stem and progenitor cells resulting in clonal expansion in individuals with no overt hematologic disease. Since CH increases in an age-related manner, understanding its role in hematopoietic cell transplantation (HCT) has become increasingly relevant to an aging transplant population. Multiple factors distinguish post-transplant hematopoiesis from unperturbed, steady-state hematopoiesis, including the influence of immunosuppressants, cytotoxic reagents, and marked proliferative stress, all of which may enhance or diminish the opportunity for clonal expansion. We reviewed the available clinical evidence on the consequences of CH at time of transplant in patients undergoing autologous HCT, and the impact of donor and recipient CH on allogeneic HCT outcomes. In the absence of evidence-based guidelines, we share our suggestions for managing donors and recipients found to have CH. Large-scale studies are needed to guide an evidence-based, uniform approach for the management of CH in the setting of HCT.