Clinical Relevance of Pre- and Post-Transplantation Residual Disease, Hematogones and Natural Killer Cells in Adult Patients with Acute Leukemia

Abstract

Abstract 4490 PurposeAllogeneic hematopoietic stem cell transplantation (allo-SCT) may rescue patients with acute myeloid and lymphoblastic leukemia (AML/ALL) even in high risk disease. Little has been investigated about prognostic impact of pre- and post-transplant residual disease (RD) status, hematogones (HG) level and natural killer (NK) cells level in the adult patients with acute leukemia. Materials & MethodsWe retrospectively studied 45 consecutive adult patients, including 31 AML and 14 ALL, receiving allo-SCT at National Taiwan University Hospital. Based on disease status at transplant, 18 patients were in standard risk; 16 in intermediate risk; and 11 in high risk disease. 28 patients underwent myeloablative conditioning and 17 received reduced-intensity SCT. Bone marrow samples were obtained both before conditioning therapy (pre-SCT) and at hemogram recovery after transplantation (post-SCT). RD, HG level and NK cells level were evaluated by multidimensional flow cytometry. Leukemia-free survival (LFS) was estimated by using Kaplan-Meier method. ResultsPre-SCT RD-negative (RD-) was shown in 26 patients and RD-positive (RD+) in 19 patients; whereas post-SCT RD- was found in 39 patients and RD+ in 6 patients. Level of pre-SCT RD status ranges from 0–90% and level of post-SCT RD status ranges from 0–3%. Estimated one-year LFS were 71.8% in pre-SCT RD- compared to 0% in pre-SCT RD+ group (P=0.008, Fig. 1). In post-SCT flow cytometric analysis, one-year LFS were 33.2% in post-SCT RD- versus 25.0% in post-SCT RD+ group (P=0.002, Fig. 2). After combining pre- and post-SCT RD status, three groups of patients were identified; pre-SCT RD−/post-SCT RD- (n=26), pre-SCT RD+/post-SCT RD- (n=13), and pre-SCT RD+/post-SCT RD+ (n=6). The classification further stratify the patients into different groups with distinct outcome (P=0.003, Fig. 3). We also found the median HG 0.2% (range 0–12%) and 0.1% (range 0–2.1%) and median NK cells 1.8% (range 0.2–20%) and 1.8% (0.02–15.5%) pre-SCT and post-SCT, respectively. The patients with higher NK cells, either pre-SCT or post-SCT, had longer LFS (P<0.001 and 0.004, continuous variables, respectively). [Display omitted] [Display omitted] [Display omitted] ConclusionOur data suggest both pre- and post-SCT RD status and NK cells level could predict the transplant outcome. Further large-scale studies may be needed to confirm this point. Disclosures:No relevant conflicts of interest to declare.