Risk Stratification-directed NAC for Prevention of Poor Hematopoietic Reconstitution

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective treatment of malignant hematopoietic diseases. However, poor hematopoietic reconstitution including poor graft function (PGF) and prolonged isolated thrombocytopenia (PT), remains a life-threatening complication after allo-HSCT. Especially with the increasing use of haploidentical allo-HSCT (haplo-HSCT) in the past ten years, PGF and PT have become growing obstacles contributing to high morbidity and mortality after allo-HSCT. Due to the limited mechanism studies, the clinical management of PGF and PT is challenging. Recent prospective case-control studies reported that the reduced and dysfunctional bone marrow (BM) endothelial cells (ECs) after allo-HSCT are involved in the pathogenesis of PGF and PT. Moreover, in vitro treatment with N-acetyl-L-cysteine (NAC) could enhance the defective hematopoietic stem cell (HSC) function through repairing the dysfunctional BM ECs of PGF and PT patients. The investigators performed a small-scale pilot cohort study and saw encouraging clinical results that oral administration with NAC could partially repair the dysfunctional BM ECs and improve megakaryocytopoiesis in PT patients, which suggests that NAC is a promising drug in PT patients after allo-HSCT. In addition, prior prospective trial of the investigators suggests that BM ECs\<0.1% pre-HSCT is the risk factor for occurrence of the PGF and PT two months following allo-HSCT. Previous single-arm clinical cohort studies of the investigators showed that prophylactic use of NAC before allo-HSCT reduced the incidence of poor hematopoietic reconstitution after allo-HSCT in patients with ECs \<0.1% pre-HSCT. Therefore, the investigators designed the study with acute leukemia patients who will be scheduled to receive haplo-HSCT. The patients who are in the first complete remission at time of haplo-transplant will be enrolled in the study. Exclusive criteria are bronchila asthma and NAC allergy. The enro