Utility of assessing CD3 (+) cell chimerism within the first months after allogeneic hematopoietic stem‐cell transplantation for acute myeloid leukemia

After allogeneic hematopoietic stem‐cell transplantation (alloHSCT), the chimerism assay is used to monitor cell engraftment and quantify the respective proportions of donor/recipient cells in blood or bone‐marrow samples. Here, we aimed to better assess the utility of determining CD3(+) cell chimerism within the first 6 months post alloHSCT. One hundred and thirty five patients diagnosed with acute myeloid leukemia were enrolled in this study. We observed significantly lower overall survival and relapse free survival for patients without full donor chimerism (<95%, <98%, <99%) in whole blood at Day 30, as well as at Day 90 after alloHSCT, than for patients with full donor chimerism. This outcome was not observed when assessing selected CD3(+) cells. However, at Day 90, patients with discordant whole blood versus selected CD3(+) cell chimerism showed both significantly lower overall survival and relapse free survival, giving an interest to assess selected cells chimerism.