Leukemia burden delays lymphocyte and platelet recovery after allo-SCT for AML

Lymphocyte and platelet recovery may influence outcomes of allo-SCT for treatment of AML. It is not clear, however, if this impact is independent of patient and transplant characteristics. To investigate this question, we evaluated the influence of pre- or post transplant factors on day +30 absolute lymphocyte count (ALC) and the speed of platelet engraftment. We studied 106 AML patients treated with fludarabine and melphalan reduced-intensity conditioning and allo-SCT. Twenty nine percent of patients were in CR at the initiation of the conditioning, 39% had active disease with circulating blasts and 32% had active disease without circulating blasts. The graft source was peripheral blood from a matched sibling donor in 55% and BM from a matched unrelated donor in 45%. Our data showed that the presence of circulating blasts before transplantation is significantly correlated with low post-SCT day +30 ALC and slow platelet engraftment. This finding suggests that the impact of early ALC and platelet recovery on transplant outcome may not be independent of disease status at transplantation.